Question: CX3CR1 on the Th2 cells suppresses airway inflammation.

Title: CX3CR1 is required for airway inflammation by promoting T helper cell survival and maintenance in inflamed lung Content: Allergic asthma is a T helper type 2 (T(H)2)-dominated disease of the lung. In people with asthma, a fraction of CD4(+) T cells express the CX3CL1 receptor, CX3CR1, and CX3CL1 expression is increased in airway smooth muscle, lung endothelium and epithelium upon allergen challenge. Here we found that untreated CX3CR1-deficient mice or wild-type (WT) mice treated with CX3CR1-blocking reagents show reduced lung disease upon allergen sensitization and challenge. Transfer of WT CD4(+) T cells into CX3CR1-deficient mice restored the cardinal features of asthma, and CX3CR1-blocking reagents prevented airway inflammation in CX3CR1-deficient recipients injected with WT T(H)2 cells. We found that CX3CR1 signaling promoted T(H)2 survival in the inflamed lungs, and injection of B cell leukemia/lymphoma-2 protein (BCl-2)-transduced CX3CR1-deficient T(H)2 cells into CX3CR1-deficient mice restored asthma. CX3CR1-induced survival was also observed for T(H)1 cells upon airway inflammation but not under homeostatic conditions or upon peripheral inflammation. Therefore, CX3CR1 and CX3CL1 may represent attractive therapeutic targets in asthma.

Title: CXCR2 mediates NADPH oxidase–independent neutrophil extracellular trap formation in cystic fibrosis airway inflammation Content: Upon activation, neutrophils release DNA fibers decorated with antimicrobial proteins, forming neutrophil extracellular traps (NETs). Although NETs are bactericidal and contribute to innate host defense, excessive NET formation has been linked to the pathogenesis of autoinflammatory diseases. However, the mechanisms regulating NET formation, particularly during chronic inflammation, are poorly understood. Here we show that the G protein–coupled receptor (GPCR) CXCR2 mediates NET formation. Downstream analyses showed that CXCR2-mediated NET formation was independent of NADPH oxidase and involved Src family kinases. We show the pathophysiological relevance of this mechanism in cystic fibrosis lung disease, characterized by chronic neutrophilic inflammation. We found abundant NETs in airway fluids of individuals with cystic fibrosis and mouse cystic fibrosis lung disease, and NET amounts correlated with impaired obstructive lung function. Pulmonary blockade of CXCR2 by intra-airway delivery of small-molecule antagonists inhibited NET formation and improved lung function in vivo without affecting neutrophil recruitment, proteolytic activity or antibacterial host defense. These studies establish CXCR2 as a receptor mediating NADPH oxidase–independent NET formation and provide evidence that this GPCR pathway is operative and druggable in cystic fibrosis lung disease.

Title: Chimeric Antigen Receptor-Redirected Regulatory T Cells Suppress Experimental Allergic Airway Inflammation, a Model of Asthma Content: Cellular therapy with chimeric antigen receptor (CAR)-redirected cytotoxic T cells has shown impressive efficacy in the treatment of hematologic malignancies. We explored a regulatory T cell (Treg)-based therapy in the treatment of allergic airway inflammation, a model for asthma, which is characterized by an airway hyper-reactivity (AHR) and a chronic, T helper-2 (Th2) cell-dominated immune response to allergen. To restore the immune balance in the lung, we redirected Tregs by a CAR toward lung epithelia in mice upon experimentally induced allergic asthma, closely mimicking the clinical situation. Adoptively transferred CAR Tregs accumulated in the lung and in tracheobronchial lymph nodes, reduced AHR and diminished eosinophilic airway inflammation, indicated by lower cell numbers in the bronchoalveolar lavage fluid and decreased cell infiltrates in the lung. CAR Treg cells furthermore prevented excessive pulmonary mucus production as well as increase in allergen-specific IgE and Th2 cytokine levels in exposed animals. CAR Tregs were more efficient in controlling asthma than non-modified Tregs, indicating the pivotal role of specific Treg cell activation in the affected organ. Data demonstrate that lung targeting CAR Treg cells ameliorate key features of experimental airway inflammation, paving the way for cell therapy of severe allergic asthma.

Title: IL-1β, IL-4 and IL-12 control the fate of group 2 innate lymphoid cells in human airway inflammation in the lungs Content: Group 2 innate lymphoid cells (ILC2s) secrete type 2 cytokines, which protect against parasites but can also contribute to a variety of inflammatory airway diseases. We report here that interleukin 1β (IL-1β) directly activated human ILC2s and that IL-12 induced the conversion of these activated ILC2s into interferon-γ (IFN-γ)-producing ILC1s, which was reversed by IL-4. The plasticity of ILCs was manifested in diseased tissues of patients with severe chronic obstructive pulmonary disease (COPD) or chronic rhinosinusitis with nasal polyps (CRSwNP), which displayed IL-12 or IL-4 signatures and the accumulation of ILC1s or ILC2s, respectively. Eosinophils were a major cellular source of IL-4, which revealed cross-talk between IL-5-producing ILC2s and IL-4-producing eosinophils. We propose that IL-12 and IL-4 govern ILC2 functional identity and that their imbalance results in the perpetuation of type 1 or type 2 inflammation.

Title: Peroxisome Proliferator Activated Receptor gamma (PPARγ) Agonist Rosiglitazone Ameliorate Airway Inflammation by Inhibiting Toll-Like Receptor 2 (TLR2)/Nod-Like Receptor with Pyrin Domain Containing 3 (NLRP3) Inflammatory Corpuscle Activation in Asthmatic Mice Content: BACKGROUND The purpose of this study was to explore the function and mechanism of peroxisome proliferator activated receptor agonist (PPARγ) in the toll-like receptor 2 (TLR2)/nod-like receptor with pyrin domain containing 3 (NLRP3) inflammatory corpuscle pathway of asthmatic mice. MATERIAL AND METHODS Eighteen female mice (C57) were randomly divided into 4 groups: the control group, the asthma model group challenged by ovalbumin (OVA), the rosiglitazone group, and the PPARγ agonist rosiglitazone treatment group. The infiltration of peribronchial inflammatory cells as well as the proliferation and mucus secretion of bronchial epithelial goblet cells were observed by hematoxylin and eosin and periodic acid-Schiff staining. Western blots were employed to detect the expression levels of TLR2, PPARγ, nuclear factor-kappa B (NF-kappaB), NLRP3, and ASC [apoptosis-associated speck-like protein containing C-terminal caspase recruitment domain [CARD]). RESULTS The number of inflammatory cells and eosinophils, and the levels of OVAs IgE, interleukin-4 (IL-4), and IL-13 were significantly higher in the C57 asthma group compared to the C57 control group and the treatment group (P<0.05). The infiltration of peribronchiolar inflammatory cells, wall thickening, goblet cell hyperplasia, and mucus secretion in the treatment group were all significantly decreased compared to those in the asthma group. PPARg expression in the treatment group was significantly higher compared to the asthma group and the control group (P<0.05). The protein expression levels of TLR2, NF-kappaB, NLRP3, and ASC were significantly lower compared to the asthma group but were higher compared to the control group (P<0.05). CONCLUSIONS PPARγ rosiglitazone ameliorates airway inflammation by inhibiting NF-kappaB expression in asthmatic mice, and further inhibits the activation of TLR2/NLRP3 inflammatory corpuscles.

Title: The Transcription Factors Egr2 and Egr3 Are Essential for the Control of Inflammation and Antigen-Induced Proliferation of B and T Cells Content: Lymphocytes provide optimal responses against pathogens with minimal inflammatory pathology. However, the intrinsic mechanisms regulating these responses are unknown. Here, we report that deletion of both transcription factors Egr2 and Egr3 in lymphocytes resulted in a lethal autoimmune syndrome with excessive serum proinflammatory cytokines but also impaired antigen receptor-induced proliferation of B and T cells. Egr2- and Egr3-defective B and T cells had hyperactive signal transducer and activator of transcription-1 (STAT1) and STAT3 while antigen receptor-induced activation of transcription factor AP-1 was severely impaired. We discovered that Egr2 and/or Egr3 directly induced expression of suppressor of cytokine signaling-1 (SOCS1) and SOCS3, inhibitors of STAT1 and STAT3, and also blocked the function of Batf, an AP-1 inhibitor, in B and T cells. Thus, Egr2 and Egr3 regulate B and T cell function in adaptive immune responses and homeostasis by promoting antigen receptor signaling and controlling inflammation.

Title: PI3K-Akt-mTORC1-S6K1/2 axis controls Th17 differentiation by regulating Gfi1 expression and nuclear translocation of RORγ. Content: The PI3K-Akt-mTORC1 axis contributes to the activation, survival, and proliferation of CD4(+) T cells upon stimulation through TCR and CD28. Here, we demonstrate that the suppression of this axis by deletion of p85α or PI3K/mTORC1 inhibitors as well as T cell-specific deletion of raptor, an essential component of mTORC1, impairs Th17 differentiation in vitro and in vivo in a S6K1/2-dependent fashion. Inhibition of PI3K-Akt-mTORC1-S6K1 axis impairs the downregulation of Gfi1, a negative regulator of Th17 differentiation. Furthermore, we demonstrate that S6K2, a nuclear counterpart of S6K1, is induced by the PI3K-Akt-mTORC1 axis, binds RORγ, and carries RORγ to the nucleus. These results point toward a pivotal role of PI3K-Akt-mTORC1-S6K1/2 axis in Th17 differentiation.

Title: CDX2 inhibits the proliferation and tumor formation of colon cancer cells by suppressing Wnt/β-catenin signaling via transactivation of GSK-3β and Axin2 expression Content: Caudal-related homeobox transcription factor 2 (CDX2), an intestine-specific nuclear transcription factor, has been strongly implicated in the tumourigenesis of various human cancers. However, the functional role of CDX2 in the development and progression of colorectal cancer (CRC) is not well known. In this study, CDX2 knockdown in colon cancer cells promoted cell proliferation in vitro, accelerated tumor formation in vivo, and induced a cell cycle transition from G0/G1 to S phase, whereas CDX2 overexpression inhibited cell proliferation. TOP/FOP-Flash reporter assay showed that CDX2 knockdown or CDX2 overexpression significantly increased or decreased Wnt signaling activity. Western blot assay showed that downstream targets of Wnt signaling, including β-catenin, cyclin D1 and c-myc, were up-regulated or down-regulated in CDX2-knockdown or CDX2-overexpressing colon cancer cells. In addition, suppression of Wnt signaling by XAV-939 led to a marked suppression of the cell proliferation enhanced by CDX2 knockdown, whereas activation of this signaling by CHIR-99021 significantly enhanced the cell proliferation inhibited by CDX2 overexpression. Dual-luciferase reporter and quantitative chromatin immunoprecipitation (qChIP) assays further confirmed that CDX2 transcriptionally activates glycogen synthase kinase-3β (GSK-3β) and axis inhibition protein 2 (Axin2) expression by directly binding to the promoter of GSK-3β and the upstream enhancer of Axin2. In conclusion, these results indicated that CDX2 inhibits the proliferation and tumor formation of colon cancer cells by suppressing Wnt/β-catenin signaling.

Title: CCR2 and CXCR4 regulate peripheral blood monocyte pharmacodynamics and link to efficacy in experimental autoimmune encephalomyelitis Content: BACKGROUND CCR2 plays a key role in regulating monocyte trafficking to sites of inflammation and therefore has been the focus of much interest as a target for inflammatory disease. METHODS Here we examined the effects of CCR2 blockade with a potent small molecule antagonist to determine the pharmacodynamic consequences on the peripheral blood monocyte compartment in the context of acute and chronic inflammatory processes. RESULTS We demonstrate that CCR2 antagonism in vivo led to a rapid decrease in the number of circulating Ly6Chi monocytes and that this decrease was largely due to the CXCR4-dependent sequestration of these cells in the bone marrow, providing pharmacological evidence for a mechanism by which monocyte dynamics are regulated in vivo. CCR2 antagonism led to an accumulation of circulating CCL2 and CCL7 levels in the blood, indicating a role for CCR2 in regulating the levels of its ligands under homeostatic conditions. Finally, we show that the pharmacodynamic changes due to CCR2 antagonism were apparent after chronic dosing in mouse experimental autoimmune encephalomyelitis, a model in which CCR2 blockade demonstrated a dramatic reduction in disease severity, manifest in a reduced accumulation of monocytes and other cells in the CNS. CONCLUSION CCR2 antagonism in vivo has tractable pharmacodynamic effects that can be used to align target engagement with biologic effects on disease activity.

Title: Metabolic reprogramming of stromal fibroblasts through p62-mTORC1 signaling promotes inflammation and tumorigenesis. Content: The tumor microenvironment plays a critical role in cancer progression, but the precise mechanisms by which stromal cells influence the epithelium are poorly understood. Here we show that p62 levels were reduced in the stroma of several tumors and that its loss in the tumor microenvironment or stromal fibroblasts resulted in increased tumorigenesis of epithelial prostate cancer cells. The mechanism involves the regulation of cellular redox through an mTORC1/c-Myc pathway of stromal glucose and amino acid metabolism, resulting in increased stromal IL-6 production, which is required for tumor promotion in the epithelial compartment. Thus, p62 is an anti-inflammatory tumor suppressor that acts through the modulation of metabolism in the tumor stroma.

Title: MicroRNA-Containing T-Regulatory-Cell-Derived Exosomes Suppress Pathogenic T Helper 1 Cells Content: Foxp3(+) T regulatory (Treg) cells prevent inflammatory disease but the mechanistic basis of suppression is not understood completely. Gene silencing by RNA interference can act in a cell-autonomous and non-cell-autonomous manner, providing mechanisms of intercellular regulation. Here, we demonstrate that non-cell-autonomous gene silencing, mediated by miRNA-containing exosomes, is a mechanism employed by Treg cells to suppress T-cell-mediated disease. Treg cells transferred microRNAs (miRNA) to various immune cells, including T helper 1 (Th1) cells, suppressing Th1 cell proliferation and cytokine secretion. Use of Dicer-deficient or Rab27a and Rab27b double-deficient Treg cells to disrupt miRNA biogenesis or the exosomal pathway, respectively, established a requirement for miRNAs and exosomes for Treg-cell-mediated suppression. Transcriptional analysis and miRNA inhibitor studies showed that exosome-mediated transfer of Let-7d from Treg cell to Th1 cells contributed to suppression and prevention of systemic disease. These studies reveal a mechanism of Treg-cell-mediated suppression mediated by miRNA-containing exosomes.

Title: Toll-like receptor-3 mediates HIV-1 transactivation via NFκB and JNK pathways and histone acetylation, but prolonged activation suppresses Tat and HIV-1 replication. Content: TLR3 has been implicated in the pathogenesis of several viral infections, including SIV- and HIV-1-induced inflammation and AIDS. However the molecular mechanisms of these TLR3-mediated effects are not known, and it is not known whether HIV interacts with cellular TLR3 to affect disease process. Here we investigate the effects of TLR3 ligands on HIV-1 transactivation using both primary human macrophages and cells containing integrated copies of the HIV-1 promoter. We demonstrate that TLR3 activation induced upregulation of transcription factors such as c-Jun, CCAAT/enhancer-binding protein alpha (CEBPA), signal transducer and activator of transcription (STAT)-1, STAT-2, RELB, and nuclear factor kappa-B1 (NFκB1), most of which are known to regulate the HIV promoter activity. We also demonstrate that TLR3 activation increased HIV-1 transactivation via the c-Jun N-terminal kinase (JNK) and NFκB pathways. This was associated with epigenetic modifications, including decreased histone deacetylase activity, increased histone acetyl transferase (HAT) activity, and increased acetylation of histones H3 and H4 at lysine residues in the nucleosome-0 and nucleosome-1 of the HIV-1 promoter. However, prolonged TLR3 activation decreased HIV-1 transactivation, decreased HAT activity and Tat transcription, and suppressed viral replication. Overall, data suggests that TLR3 can act as viral sensor to mediate viral transactivation, cellular signaling, innate immune response, and inflammation in HIV-infected humans. Our study provides novel insights into the molecular basis for these TLR3-mediated effects.

Title: A complex secretory program orchestrated by the inflammasome controls paracrine senescence Content: Oncogene-induced senescence (OIS) is crucial for tumour suppression. Senescent cells implement a complex pro-inflammatory response termed the senescence-associated secretory phenotype (SASP). The SASP reinforces senescence, activates immune surveillance and paradoxically also has pro-tumorigenic properties. Here, we present evidence that the SASP can also induce paracrine senescence in normal cells both in culture and in human and mouse models of OIS in vivo. Coupling quantitative proteomics with small-molecule screens, we identified multiple SASP components mediating paracrine senescence, including TGF-β family ligands, VEGF, CCL2 and CCL20. Amongst them, TGF-β ligands play a major role by regulating p15(INK4b) and p21(CIP1). Expression of the SASP is controlled by inflammasome-mediated IL-1 signalling. The inflammasome and IL-1 signalling are activated in senescent cells and IL-1α expression can reproduce SASP activation, resulting in senescence. Our results demonstrate that the SASP can cause paracrine senescence and impact on tumour suppression and senescence in vivo.

Title: Conventional and monocyte-derived CD11b(+) dendritic cells initiate and maintain T helper 2 cell-mediated immunity to house dust mite allergen. Content: Dendritic cells (DCs) are crucial for mounting allergic airway inflammation, but it is unclear which subset of DCs performs this task. By using CD64 and MAR-1 staining, we reliably separated CD11b(+) monocyte-derived DCs (moDCs) from conventional DCs (cDCs) and studied antigen uptake, migration, and presentation assays of lung and lymph node (LN) DCs in response to inhaled house dust mite (HDM). Mainly CD11b(+) cDCs but not CD103(+) cDCs induced T helper 2 (Th2) cell immunity in HDM-specific T cells in vitro and asthma in vivo. Studies in Flt3l(-/-) mice, lacking all cDCs, revealed that moDCs were also sufficient to induce Th2 cell-mediated immunity but only when high-dose HDM was given. The main function of moDCs was the production of proinflammatory chemokines and allergen presentation in the lung during challenge. Thus, we have identified migratory CD11b(+) cDCs as the principal subset inducing Th2 cell-mediated immunity in the LN, whereas moDCs orchestrate allergic inflammation in the lung.

Title: A CXCL1 Paracrine Network Links Cancer Chemoresistance and Metastasis Content: Metastasis and chemoresistance in cancer are linked phenomena, but the molecular basis for this link is unknown. We uncovered a network of paracrine signals between carcinoma, myeloid, and endothelial cells that drives both processes in breast cancer. Cancer cells that overexpress CXCL1 and 2 by transcriptional hyperactivation or 4q21 amplification are primed for survival in metastatic sites. CXCL1/2 attract CD11b(+)Gr1(+) myeloid cells into the tumor, which produce chemokines including S100A8/9 that enhance cancer cell survival. Although chemotherapeutic agents kill cancer cells, these treatments trigger a parallel stromal reaction leading to TNF-α production by endothelial and other stromal cells. TNF-α via NF-kB heightens the CXCL1/2 expression in cancer cells, thus amplifying the CXCL1/2-S100A8/9 loop and causing chemoresistance. CXCR2 blockers break this cycle, augmenting the efficacy of chemotherapy against breast tumors and particularly against metastasis. This network of endothelial-carcinoma-myeloid signaling interactions provides a mechanism linking chemoresistance and metastasis, with opportunities for intervention.

Title: p62/SQSTM1 by Binding to Vitamin D Receptor Inhibits Hepatic Stellate Cell Activity, Fibrosis, and Liver Cancer. Content: Hepatic stellate cells (HSCs) play critical roles in liver fibrosis and hepatocellular carcinoma (HCC). Vitamin D receptor (VDR) activation in HSCs inhibits liver inflammation and fibrosis. We found that p62/SQSTM1, a protein upregulated in liver parenchymal cells but downregulated in HCC-associated HSCs, negatively controls HSC activation. Total body or HSC-specific p62 ablation potentiates HSCs and enhances inflammation, fibrosis, and HCC progression. p62 directly interacts with VDR and RXR promoting their heterodimerization, which is critical for VDR:RXR target gene recruitment. Loss of p62 in HSCs impairs the repression of fibrosis and inflammation by VDR agonists. This demonstrates that p62 is a negative regulator of liver inflammation and fibrosis through its ability to promote VDR signaling in HSCs, whose activation supports HCC.

Title: TLR-activated B cells suppress T cell-mediated autoimmunity. Content: TLR sense microbial infections, and control activation of immune responses. Dendritic cells, macrophages, and B lymphocytes express TLR and the TLR-signaling adaptor protein MyD88. The impact of TLR-activated B cells on T cell-mediated inflammation is unknown. In this study, we have used mice carrying B cell-restricted deficiencies in MyD88 or in distinct TLR to examine the impact of TLR-activated B cells on a T cell-mediated autoimmune disease, experimental autoimmune encephalomyelitis (EAE). We demonstrate that TLR-signaling in B cells suppresses inflammatory T cell responses (both Th1 and Th17), and stimulates recovery from EAE. Only certain TLR are required on B cells for resolution of EAE, and these are dispensable for disease initiation, indicating that a category of TLR agonists preferentially triggers a suppressive function in B cells and thereby limits autoimmune disease. The TLR agonists controlling the regulatory function of B cells are provided by components of Mycobacterium tuberculosis present in the adjuvant. Thus, MyD88 signaling in B cells antagonizes MyD88 signaling in other cells, which drives differentiation of Th17 cells and is required for induction of EAE. Altogether, our data indicate that B cells link recognition of microbial products via TLR to suppression of a T cell-mediated autoimmune disease.

Title: Local Ca2+ influx through Ca2+ release-activated Ca2+ (CRAC) channels stimulates production of an intracellular messenger and an intercellular pro-inflammatory signal. Content: Ca2+ entry through store-operated Ca2+ channels drives the production of the pro-inflammatory molecule leukotriene C4 (LTC4) from mast cells through a pathway involving Ca2+-dependent protein kinase C, mitogen-activated protein kinases ERK1/2, phospholipase A2, and 5-lipoxygenase. Here we examine whether local Ca2+ influx through store-operated Ca2+ release-activated Ca2+ (CRAC) channels in the plasma membrane stimulates this signaling pathway. Manipulating the amplitude and spatial extent of Ca2+ entry by altering chemical and electrical gradients for Ca2+ influx or changing the Ca2+ buffering of the cytoplasm all impacted on protein kinase C and ERK activation, generation of arachidonic acid and LTC4 secretion, with little change in the bulk cytoplasmic Ca2+ rise. Similar bulk cytoplasmic Ca2+ concentrations were achieved when CRAC channels were activated in 0.25 mm external Ca2+ versus 2 mm Ca2+ and 100 nm La3+, an inhibitor of CRAC channels. However, despite similar bulk cytoplasmic Ca2+, protein kinase C activation and LTC4 secretion were larger in 2 mm Ca2+ and La3+ than in 0.25 mm Ca2+, consistent with the central involvement of a subplasmalemmal Ca2+ rise. The nonreceptor tyrosine kinase Syk coupled CRAC channel opening to protein kinase C and ERK activation. Recombinant TRPC3 channels also activated protein kinase C, suggesting that subplasmalemmal Ca2+ rather than a microdomain exclusive to CRAC channels is the trigger. Hence a subplasmalemmal Ca2+ increase in mast cells is highly versatile in that it triggers cytoplasmic responses through generation of intracellular messengers as well as long distance changes through increased secretion of paracrine signals.

Title: Hypoxia‐Sensitive COMMD1 Integrates Signaling and Cellular Metabolism in Human Macrophages and Suppresses Osteoclastogenesis Content: Summary Hypoxia augments inflammatory responses and osteoclastogenesis by incompletely understood mechanisms. We identified COMMD1 as a cell‐intrinsic negative regulator of osteoclastogenesis that is suppressed by hypoxia. In human macrophages, COMMD1 restrained induction of NF‐&kgr;B signaling and a transcription factor E2F1‐dependent metabolic pathway by the cytokine RANKL. Downregulation of COMMD1 protein expression by hypoxia augmented RANKL‐induced expression of inflammatory and E2F1 target genes and downstream osteoclastogenesis. E2F1 targets included glycolysis and metabolic genes including CKB that enabled cells to meet metabolic demands in challenging environments, as well as inflammatory cytokine‐driven target genes. Expression quantitative trait locus analysis linked increased COMMD1 expression with decreased bone erosion in rheumatoid arthritis. Myeloid deletion of Commd1 resulted in increased osteoclastogenesis in arthritis and inflammatory osteolysis models. These results identify COMMD1 and an E2F‐metabolic pathway as key regulators of osteoclastogenic responses under pathological inflammatory conditions and provide a mechanism by which hypoxia augments inflammation and bone destruction. Graphical Abstract Figure. No Caption available. HighlightsCOMMD1 is a negative regulator of osteoclast differentiationCOMMD1 suppresses bone loss in RA and inflammatory arthritis and osteolysis modelsCOMMD1 negatively regulates E2F1‐dependent metabolic pathways in macrophagesHypoxia suppresses COMMD1 expression to augment osteoclastogenesis &NA; Pathways that promote osteoclastogenesis are well characterized but less is known about negative regulators that suppress pathological bone loss. Murata et al. identify COMMD1 as an inhibitor of osteoclastogenesis that restrains NF‐&kgr;B‐ and E2F1‐CKB‐mediated metabolic pathways in macrophages.

Title: Kruppel-like factor KLF10 targets transforming growth factor-beta1 to regulate CD4(+)CD25(-) T cells and T regulatory cells. Content: CD4(+)CD25(+) regulatory T cells (T regs) play a major role in the maintenance of self-tolerance and immune suppression, although the mechanisms controlling T reg development and suppressor function remain incompletely understood. Herein, we provide evidence that Kruppel-like factor 10 (KLF10/TIEG1) constitutes an important regulator of T regulatory cell suppressor function and CD4(+)CD25(-) T cell activation through distinct mechanisms involving transforming growth factor (TGF)-beta1 and Foxp3. KLF10 overexpressing CD4(+)CD25(-) T cells induced both TGF-beta1 and Foxp3 expression, an effect associated with reduced T-Bet (Th1 marker) and Gata3 (Th2 marker) mRNA expression. Consistently, KLF10(-/-) CD4(+)CD25(-) T cells have enhanced differentiation along both Th1 and Th2 pathways and elaborate higher levels of Th1 and Th2 cytokines. Furthermore, KLF10(-/-) CD4(+)CD25(-) T cell effectors cannot be appropriately suppressed by wild-type T regs. Surprisingly, KLF10(-/-) T reg cells have reduced suppressor function, independent of Foxp3 expression, with decreased expression and elaboration of TGF-beta1, an effect completely rescued by exogenous treatment with TGF-beta1. Mechanistic studies demonstrate that in response to TGF-beta1, KLF10 can transactivate both TGF-beta1 and Foxp3 promoters, implicating KLF10 in a positive feedback loop that may promote cell-intrinsic control of T cell activation. Finally, KLF10(-/-) CD4(+)CD25(-) T cells promoted atherosclerosis by approximately 2-fold in ApoE(-/-)/scid/scid mice with increased leukocyte accumulation and peripheral pro-inflammatory cytokines. Thus, KLF10 is a critical regulator in the transcriptional network controlling TGF-beta1 in both CD4(+)CD25(-) T cells and T regs and plays an important role in regulating atherosclerotic lesion formation in mice.

Title: A direct role for IFN-gamma in regulation of Th1 cell development. Content: IL-12 has been identified as a major cytokine influencing the differentiation of CD4 cells to a Th1 phenotype, whereas a role for IFN-gamma is controversial. We investigated the interrelationship between IL-12 and IFN-gamma in promoting Th1 responses using naive CD4 cells reactive with pigeon cytochrome c from TCR transgenics and memory CD4 cells derived by in vivo priming with KLH. Without exogenous rIL-12 or rIFN-gamma, primary and memory effectors induced by Ag or anti-CD3 and anti-CD28 secreted variable levels of IL-2 and IFN-gamma. The level of IFN-gamma secreted by effectors correlated with endogenous IFN-gamma produced in primary cultures, and anti-IFN-gamma largely inhibited the development of effectors producing IFN-gamma. With optimal TCR stimulation and costimulation, endogenous IFN-gamma, without IL-12, was sufficient to elicit Th1 cells via an autocrine mechanism, whereas with suboptimal stimulation, exogenous rIFN-gamma or rIL-12 was required for Th1 development. However, rIL-12 was more effective than rIFN-gamma, partially because rIL-12 greatly enhanced autocrine production of IFN-gamma, and optimal development of the Th1 phenotype was mediated by the synergistic actions of both cytokines. Thus, both IFN-gamma and IL-12 can independently regulate Th1 development, but because of IFN-gamma-mediated feedback, their relative contributions are determined by the conditions of T cell stimulation. The extent of differentiation to a Th1 phenotype may, therefore, depend on the availability of both APC-derived IL-12 and autocrine IFN-gamma consequent to the overall strength of T cell stimulation.

Title: Activin–like kinase–3 activity is important for kidney regeneration and reversal of fibrosis Content: Molecules associated with the transforming growth factor β (TGF-β) superfamily, such as bone morphogenic proteins (BMPs) and TGF-β, are key regulators of inflammation, apoptosis and cellular transitions. Here we show that the BMP receptor activin-like kinase 3 (Alk3) is elevated early in diseased kidneys after injury. We also found that its deletion in the tubular epithelium leads to enhanced TGF-β1-Smad family member 3 (Smad3) signaling, epithelial damage and fibrosis, suggesting a protective role for Alk3-mediated signaling in the kidney. A structure-function analysis of the BMP-Alk3-BMP receptor, type 2 (BMPR2) ligand-receptor complex, along with synthetic organic chemistry, led us to construct a library of small peptide agonists of BMP signaling that function through the Alk3 receptor. One such peptide agonist, THR-123, suppressed inflammation, apoptosis and the epithelial-to-mesenchymal transition program and reversed established fibrosis in five mouse models of acute and chronic renal injury. THR-123 acts specifically through Alk3 signaling, as mice with a targeted deletion for Alk3 in their tubular epithelium did not respond to therapy with THR-123. Combining THR-123 and the angiotensin-converting enzyme inhibitor captopril had an additive therapeutic benefit in controlling renal fibrosis. Our studies show that BMP signaling agonists constitute a new line of therapeutic agents with potential utility in the clinic to induce regeneration, repair and reverse established fibrosis.

Title: A link between inflammation and metastasis: serum amyloid A1 and A3 induce metastasis, and are targets of metastasis-inducing S100A4 Content: S100A4 is implicated in metastasis and chronic inflammation, but its function remains uncertain. Here we establish an S100A4-dependent link between inflammation and metastatic tumor progression. We found that the acute-phase response proteins serum amyloid A (SAA) 1 and SAA3 are transcriptional targets of S100A4 via Toll-like receptor 4 (TLR4)/nuclear factor-κB signaling. SAA proteins stimulated the transcription of RANTES (regulated upon activation normal T-cell expressed and presumably secreted), G-CSF (granulocyte-colony-stimulating factor) and MMP2 (matrix metalloproteinase 2), MMP3, MMP9 and MMP13. We have also shown for the first time that SAA stimulate their own transcription as well as that of proinflammatory S100A8 and S100A9 proteins. Moreover, they strongly enhanced tumor cell adhesion to fibronectin, and stimulated migration and invasion of human and mouse tumor cells. Intravenously injected S100A4 protein induced expression of SAA proteins and cytokines in an organ-specific manner. In a breast cancer animal model, ectopic expression of SAA1 or SAA3 in tumor cells potently promoted widespread metastasis formation accompanied by a massive infiltration of immune cells. Furthermore, coordinate expression of S100A4 and SAA in tumor samples from colorectal carcinoma patients significantly correlated with reduced overall survival. These data show that SAA proteins are effectors for the metastasis-promoting functions of S100A4, and serve as a link between inflammation and tumor progression.

Title: The histone demethylases Jhdm1a/1b enhance somatic cell reprogramming in a vitamin-C-dependent manner. Content: Reprogramming of somatic cells into induced pluripotent stem cells (iPSCs) resets the epigenome to an embryonic-like state. Vitamin C enhances the reprogramming process, but the underlying mechanisms are unclear. Here we show that the histone demethylases Jhdm1a/1b are key effectors of somatic cell reprogramming downstream of vitamin C. We first observed that vitamin C induces H3K36me2/3 demethylation in mouse embryonic fibroblasts in culture and during reprogramming. We then identified Jhdm1a/1b, two known vitamin-C-dependent H3K36 demethylases, as potent regulators of reprogramming through gain- and loss-of-function approaches. Furthermore, we found that Jhdm1b accelerates cell cycle progression and suppresses cell senescence during reprogramming by repressing the Ink4/Arf locus. Jhdm1b also cooperates with Oct4 to activate the microRNA cluster 302/367, an integral component of the pluripotency machinery. Our results therefore reveal a role for H3K36me2/3 in cell fate determination and establish a link between histone demethylases and vitamin-C-induced reprogramming.

Title: Thyroid hormone inhibits lung fibrosis in mice by improving epithelial mitochondrial function Content: Thyroid hormone (TH) is critical for the maintenance of cellular homeostasis during stress responses, but its role in lung fibrosis is unknown. Here we found that the activity and expression of iodothyronine deiodinase 2 (DIO2), an enzyme that activates TH, were higher in lungs from patients with idiopathic pulmonary fibrosis than in control individuals and were correlated with disease severity. We also found that Dio2-knockout mice exhibited enhanced bleomycin-induced lung fibrosis. Aerosolized TH delivery increased survival and resolved fibrosis in two models of pulmonary fibrosis in mice (intratracheal bleomycin and inducible TGF-β1). Sobetirome, a TH mimetic, also blunted bleomycin-induced lung fibrosis. After bleomycin-induced injury, TH promoted mitochondrial biogenesis, improved mitochondrial bioenergetics and attenuated mitochondria-regulated apoptosis in alveolar epithelial cells both in vivo and in vitro. TH did not blunt fibrosis in Ppargc1a- or Pink1-knockout mice, suggesting dependence on these pathways. We conclude that the antifibrotic properties of TH are associated with protection of alveolar epithelial cells and restoration of mitochondrial function and that TH may thus represent a potential therapy for pulmonary fibrosis.

Title: Suppression of inflammatory and neuropathic pain by uncoupling CRMP-2 from the presynaptic Ca2+ channel complex Content: The use of N-type voltage-gated calcium channel (CaV2.2) blockers to treat pain is limited by many physiological side effects. Here we report that inflammatory and neuropathic hypersensitivity can be suppressed by inhibiting the binding of collapsin response mediator protein 2 (CRMP-2) to CaV2.2 and thereby reducing channel function. A peptide of CRMP-2 fused to the HIV transactivator of transcription (TAT) protein (TAT-CBD3) decreased neuropeptide release from sensory neurons and excitatory synaptic transmission in dorsal horn neurons, reduced meningeal blood flow, reduced nocifensive behavior induced by formalin injection or corneal capsaicin application and reversed neuropathic hypersensitivity produced by an antiretroviral drug. TAT-CBD3 was mildly anxiolytic without affecting memory retrieval, sensorimotor function or depression. At doses tenfold higher than that required to reduce hypersensitivity in vivo, TAT-CBD3 caused a transient episode of tail kinking and body contortion. By preventing CRMP-2–mediated enhancement of CaV2.2 function, TAT-CBD3 alleviated inflammatory and neuropathic hypersensitivity, an approach that may prove useful in managing chronic pain.

Title: Chemokine receptor trio: CXCR3, CXCR4 and CXCR7 crosstalk via CXCL11 and CXCL12. Content: Although chemokines are well established to function in immunity and endothelial cell activation and proliferation, a rapidly growing literature suggests that CXC Chemokine receptors CXCR3, CXCR4 and CXCR7 are critical in the development and progression of solid tumors. The effect of these chemokine receptors in tumorigenesis is mediated via interactions with shared ligands I-TAC (CXCL11) and SDF-1 (CXCL12). Over the last decade, CXCR4 has been extensively reported to be overexpressed in most human solid tumors and has earned considerable attention toward elucidating its role in cancer metastasis. To enrich the existing armamentarium of anti-cancerous agents, many inhibitors of CXCL12-CXCR4 axis have emerged as additional or alternative agents for neo-adjuvant treatments and even many of them are in preclinical and clinical stages of their development. However, the discovery of CXCR7 as another receptor for CXCL12 with rather high binding affinity and recent reports about its involvement in cancer progression, has questioned the potential of "selective blockade" of CXCR4 as cancer chemotherapeutics. Interestingly, CXCR7 can also bind another chemokine CXCL11, which is an established ligand for CXCR3. Recent reports have documented that CXCR3 and their ligands are overexpressed in different solid tumors and regulate tumor growth and metastasis. Therefore, it is important to consider the interactions and crosstalk between these three chemokine receptors and their ligand mediated signaling cascades for the development of effective anti-cancer therapies. Emerging evidence also indicates that these receptors are differentially expressed in tumor endothelial cells as well as in cancer stem cells, suggesting their direct role in regulating tumor angiogenesis and metastasis. In this review, we will focus on the signals mediated by this receptor trio via their shared ligands and their role in tumor growth and progression.

Title: Phosphorylation of Janus kinase 1 (JAK1) by AMP-activated protein kinase (AMPK) links energy sensing to anti-inflammatory signaling Content: Adenosine 5′-monophosphate–activated protein kinase (AMPK) is a pivotal regulator of metabolism at cellular and organismal levels. AMPK also suppresses inflammation. We found that pharmacological activation of AMPK rapidly inhibited the Janus kinase (JAK)–signal transducer and activator of transcription (STAT) pathway in various cells. In vitro kinase assays revealed that AMPK directly phosphorylated two residues (Ser515 and Ser518) within the Src homology 2 domain of JAK1. Activation of AMPK enhanced the interaction between JAK1 and 14-3-3 proteins in cultured vascular endothelial cells and fibroblasts, an effect that required the presence of Ser515 and Ser518 and was abolished in cells lacking AMPK catalytic subunits. Mutation of Ser515 and Ser518 abolished AMPK-mediated inhibition of JAK-STAT signaling stimulated by either the sIL-6Rα/IL-6 complex or the expression of a constitutively active V658F-mutant JAK1 in human fibrosarcoma cells. Clinically used AMPK activators metformin and salicylate enhanced the inhibitory phosphorylation of endogenous JAK1 and inhibited STAT3 phosphorylation in primary vascular endothelial cells. Therefore, our findings reveal a mechanism by which JAK1 function and inflammatory signaling may be suppressed in response to metabolic stress and provide a mechanistic rationale for the investigation of AMPK activators in a range of diseases associated with enhanced activation of the JAK-STAT pathway.

Title: Orai1/CRACM1 overexpression suppresses cell proliferation via attenuation of the store-operated calcium influx-mediated signalling pathway in A549 lung cancer cells. Content: BACKGROUND Orai1/CRACM1 is a principal component of the store-operated calcium channels. Store-operated calcium influx is highly correlated with inflammatory reactions, immunological regulation, and cell proliferation. Epidermal growth factor (EGF), which plays an important role in the regulation of cell proliferation, can activate store-operated calcium channels. However, the consequences of Orai1/CRACM1 overexpression in EGF-mediated lung cancer cells growth are not known. METHODS To investigate the role of Orai1/CRACM1 in EGF-mediated lung cancer cell proliferation, Orai1/CRACM1 plasmids were transfected into cells by lipofection. A cell proliferation assay, immunofluorescence staining, flow cytometry, and real-time polymerase chain reaction were employed to monitor cell proliferation. The calcium influx signals were investigated using a fluorescent-based calcium assay. RESULTS Transfection of Orai1/CRACM1 plasmids resulted in the inhibition of EGF-mediated cell proliferation. ERK1/2 and Akt phosphorylation were inhibited by Orai1/CRACM1 overexpression. Expression of the cell cycle modulator p21 was induced in the Orai1/CRACM1-overexpressing cells, whereas the expression of cyclin D3 was reduced. Flow cytometry revealed that overexpression of Orai1/CRACM1 resulted in G0/G1 cell cycle arrest. Importantly, Orai1/CRACM1 overexpression significantly attenuated EGF-mediated store-operated calcium influx. In addition, application of 2-APB, a store-operated calcium channel inhibitor, resulted in the inhibition of EGF-mediated cancer cell proliferation. CONCLUSIONS We conclude that Orai1/CRACM1 overexpression attenuates store-operated Ca(2+) influx that in turn blocks EGF-mediated proliferative signaling and drives cell cycle arrest.

Title: Th2 cytokine response in Major Depressive Disorder patients before treatment Content: In Major Depressive Disorder (MDD), the neuroendocrine and immune systems interactions are impaired. We investigated the pro/anti-inflammatory Th1/Th2 cytokine balance in MDD patients and in non-depressed control group. The MDD subjects showed higher levels of cortisol and TNF-alpha, increased CD3+CD8+ and NK percentages, diminished B cell counts and no significant variations in CD3+CD4+ lymphocyte. Moreover, higher levels of IL-4 and IL-13 (Th2) and significantly lower measurements of IL-2 and IFN-gamma (Th1) cytokines were also observed in the MDD group. Overall, we propose that all these changes could be related to the elevated cortisol levels seen in the MDD patients. Further studies are necessary to explore these findings and its implication in future therapeutic approach of MDD patients.

Title: Morin Exhibits Anti-Inflammatory Effects on IL-1β-Stimulated Human Osteoarthritis Chondrocytes by Activating the Nrf2 Signaling Pathway Content: Background/Aims: Osteoarthritis (OA) is a multifactorial disease that is associated with inflammation in joints. The purpose of the present study was to investigate the anti-inflammatory activity and mechanism of morin on human osteoarthritis chondrocytes stimulated by IL-1β. Methods: The levels of NO and PGE2 were measured by the Griess method and ELISA. The levels of MMP1, MMP3, and MMP13 were also measured by ELISA. Results: The results revealed that IL-1β significantly increased the production of NO, PGE2, MMP1, MMP3, and MMP13. Additionally, the increases were significantly attenuated by treatment with morin. Furthermore, IL-1β-induced NF-κB activation was suppressed by morin. In addition, the expression of Nrf2 and HO-1 were increased by morin and knockdown of Nrf2 could prevent the anti-inflammatory effects of morin. Conclusion: In conclusion, this study suggested that morin attenuated IL-1β-induced inflammation by activating the Nrf2 signaling pathway.

Title: BCL-6 represses genes that function in lymphocyte differentiation, inflammation, and cell cycle control. Content: BCL-6, a transcriptional repressor frequently translocated in lymphomas, regulates germinal center B cell differentiation and inflammation. DNA microarray screening identified genes repressed by BCL-6, including many lymphocyte activation genes, suggesting that BCL-6 modulates B cell receptor signals. BCL-6 repression of two chemokine genes, MIP-1alpha and IP-10, may also attenuate inflammatory responses. Blimp-1, another BCL-6 target, is important for plasmacytic differentiation. Since BCL-6 expression is silenced in plasma cells, repression of blimp-1 by BCL-6 may control plasmacytic differentiation. Indeed, inhibition of BCL-6 function initiated changes indicative of plasmacytic differentiation, including decreased expression of c-Myc and increased expression of the cell cycle inhibitor p27kip1. These data suggest that malignant transformation by BCL-6 involves inhibition of differentiation and enhanced proliferation.

Title: Retinoic acid inhibits Th17 polarization and enhances FoxP3 expression through a Stat-3/Stat-5 independent signaling pathway. Content: CD4(+) helper T (Th) cells play a crucial role in the delicate balance between host defense and autoimmune disease. Two important populations of helper T cells are the proinflammatory, interleukin-17 (IL-17)-producing (Th17) cells and the anti-inflammatory forkhead box P3-positive (FoxP3(+)) T regulatory (Treg) cells. Here we show that all-trans retinoic acid (ATRA) and other agonists of the retinoic acid receptor alpha (RARalpha) inhibit the formation of Th17 cells and promote FoxP3 expression. Conversely, inhibition of retinoic acid signaling constrains transforming growth factor beta (TGF-beta1) induction of FoxP3. The effect of ATRA is mediated independently of IL-2, signal transducer and activator of transcription 5 (Stat5) and Stat3, representing a novel mechanism for the induction of FoxP3 in CD4 T cells. As previous studies have shown that vitamin A derivatives are protective in animal models of autoimmune disease, the current data suggest a previously unrecognized role for RARalpha in the regulation of CD4(+) T-cell differentiation and provide a mechanism for the anti-inflammatory effects of retinoic acid.

Title: Control of signaling-mediated clearance of apoptotic cells by the tumor suppressor p53 Content: The inefficient clearance of dying cells can lead to abnormal immune responses, such as unresolved inflammation and autoimmune conditions. We show that tumor suppressor p53 controls signaling-mediated phagocytosis of apoptotic cells through its target, Death Domain1α (DD1α), which suggests that p53 promotes both the proapoptotic pathway and postapoptotic events. DD1α appears to function as an engulfment ligand or receptor that engages in homophilic intermolecular interaction at intercellular junctions of apoptotic cells and macrophages, unlike other typical scavenger receptors that recognize phosphatidylserine on the surface of dead cells. DD1α-deficient mice showed in vivo defects in clearing dying cells, which led to multiple organ damage indicative of immune dysfunction. p53-induced expression of DD1α thus prevents persistence of cell corpses and ensures efficient generation of precise immune responses.

Title: Reverse engineering of TLX oncogenic transcriptional networks identifies RUNX1 as tumor suppressor in T-ALL Content: The TLX1 and TLX3 transcription factor oncogenes have a key role in the pathogenesis of T cell acute lymphoblastic leukemia (T-ALL). Here we used reverse engineering of global transcriptional networks to decipher the oncogenic regulatory circuit controlled by TLX1 and TLX3. This systems biology analysis defined T cell leukemia homeobox 1 (TLX1) and TLX3 as master regulators of an oncogenic transcriptional circuit governing T-ALL. Notably, a network structure analysis of this hierarchical network identified RUNX1 as a key mediator of the T-ALL induced by TLX1 and TLX3 and predicted a tumor-suppressor role for RUNX1 in T cell transformation. Consistent with these results, we identified recurrent somatic loss-of-function mutations in RUNX1 in human T-ALL. Overall, these results place TLX1 and TLX3 at the top of an oncogenic transcriptional network controlling leukemia development, show the power of network analyses to identify key elements in the regulatory circuits governing human cancer and identify RUNX1 as a tumor-suppressor gene in T-ALL.

Title: Ketamine reduces LPS-induced HMGB1 via activation of the Nrf2/HO-1 pathway and NF-κB suppression. Content: BACKGROUND Ketamine, as an anesthetic agent, has an anti-inflammatory effect. In the present study, we investigated whether ketamine inhibits release of high mobility group box 1 (HMGB1), a late-phase cytokine of sepsis, in lipopolysaccharide (LPS)-stimulated macrophages through heme oxygenase-1 (HO-1) induction. METHODS Macrophages were preincubated with various concentrations of ketamine and then treated with LPS (1 μg/mL). The cell culture supernatants were collected to measure inflammatory mediators (HMGB1, nitric oxide, tumor necrosis factor-α, and interleukin 1β) by enzyme-linked immunosorbent assay. Moreover, HO-1 protein expression, the phosphorylation and degradation of IκB-α, and the nuclear translocation of nuclear factor E2-related factor 2 and nuclear factor κB (NF-κB) p65 were tested by Western blot analysis. In addition, to further identify the role of HO-1 in this process, tin protoporphyrin (SnPP), an HO-1 inhibitor, was used. RESULTS Ketamine treatment dose-dependently attenuated the increased levels of proinflammatory mediators (HMGB1, nitric oxide, tumor necrosis factor α, and interleukin 1β) and increased the HO-1 protein expression in LPS-activated macrophages. Furthermore, ketamine suppressed the phosphorylation and degradation of IκB-α as well as the LPS-stimulated nuclear translocation of NF-κB p65 in macrophages. In addition, the present study also demonstrated that ketamine induced HO-1 expression through the nuclear translocation of nuclear factor E2-related factor 2 in macrophages. The effects of ketamine on LPS-induced proinflammatory cytokines production were partially reversed by the HO inhibitor tin protoporphyrin (SnPP). CONCLUSION Ketamine inhibits the release of HMGB1 in LPS-stimulated macrophages, and this effect is at least partly mediated by the activation of the Nrf2/HO-1 pathway and NF-κB suppression.

Title: PTEN Regulates PI(3,4)P2 Signaling Downstream of Class I PI3K Content: The PI3K signaling pathway regulates cell growth and movement and is heavily mutated in cancer. Class I PI3Ks synthesize the lipid messenger PI(3,4,5)P3. PI(3,4,5)P3 can be dephosphorylated by 3- or 5-phosphatases, the latter producing PI(3,4)P2. The PTEN tumor suppressor is thought to function primarily as a PI(3,4,5)P3 3-phosphatase, limiting activation of this pathway. Here we show that PTEN also functions as a PI(3,4)P2 3-phosphatase, both in vitro and in vivo. PTEN is a major PI(3,4)P2 phosphatase in Mcf10a cytosol, and loss of PTEN and INPP4B, a known PI(3,4)P2 4-phosphatase, leads to synergistic accumulation of PI(3,4)P2, which correlated with increased invadopodia in epidermal growth factor (EGF)-stimulated cells. PTEN deletion increased PI(3,4)P2 levels in a mouse model of prostate cancer, and it inversely correlated with PI(3,4)P2 levels across several EGF-stimulated prostate and breast cancer lines. These results point to a role for PI(3,4)P2 in the phenotype caused by loss-of-function mutations or deletions in PTEN.

Title: The Transcription Factor T-bet Regulates Intestinal Inflammation Mediated by Interleukin-7 Receptor+ Innate Lymphoid Cells Content: Mice lacking the transcription factor T-bet in the innate immune system develop microbiota-dependent colitis. Here, we show that interleukin-17A (IL-17A)-producing IL-7Rα(+) innate lymphoid cells (ILCs) were potent promoters of disease in Tbx21(-/-)Rag2(-/-) ulcerative colitis (TRUC) mice. TNF-α produced by CD103(-)CD11b(+) dendritic cells synergized with IL-23 to drive IL-17A production by ILCs, demonstrating a previously unrecognized layer of cellular crosstalk between dendritic cells and ILCs. We have identified Helicobacter typhlonius as a key disease trigger driving excess TNF-α production and promoting colitis in TRUC mice. Crucially, T-bet also suppressed the expression of IL-7R, a key molecule involved in controlling intestinal ILC homeostasis. The importance of IL-7R signaling in TRUC disease was highlighted by the dramatic reduction in intestinal ILCs and attenuated colitis following IL-7R blockade. Taken together, these data demonstrate the mechanism by which T-bet regulates the complex interplay between mucosal dendritic cells, ILCs, and the intestinal microbiota.

Title: NVP-BEZ235, a dual PI3K/mTOR inhibitor, prevents PI3K signaling and inhibits the growth of cancer cells with activating PI3K mutations. Content: Phosphatidylinositol-3-kinase (PI3K) pathway deregulation is a common event in human cancer, either through inactivation of the tumor suppressor phosphatase and tensin homologue deleted from chromosome 10 or activating mutations of p110-alpha. These hotspot mutations result in oncogenic activity of the enzyme and contribute to therapeutic resistance to the anti-HER2 antibody trastuzumab. The PI3K pathway is, therefore, an attractive target for cancer therapy. We have studied NVP-BEZ235, a dual inhibitor of the PI3K and the downstream mammalian target of rapamycin (mTOR). NVP-BEZ235 inhibited the activation of the downstream effectors Akt, S6 ribosomal protein, and 4EBP1 in breast cancer cells. The antiproliferative activity of NVP-BEZ235 was superior to the allosteric selective mTOR complex inhibitor everolimus in a panel of 21 cancer cell lines of different origin and mutation status. The described Akt activation due to mTOR inhibition was prevented by higher doses of NVP-BEZ235. NVP-BEZ235 reversed the hyperactivation of the PI3K/mTOR pathway caused by the oncogenic mutations of p110-alpha, E545K, and H1047R, and inhibited the proliferation of HER2-amplified BT474 cells exogenously expressing these mutations that render them resistant to trastuzumab. In trastuzumab-resistant BT474 H1047R breast cancer xenografts, NVP-BEZ235 inhibited PI3K signaling and had potent antitumor activity. In treated animals, there was complete inhibition of PI3K signaling in the skin at pharmacologically active doses, suggesting that skin may serve as surrogate tissue for pharmacodynamic studies. In summary, NVP-BEZ235 inhibits the PI3K/mTOR axis and results in antiproliferative and antitumoral activity in cancer cells with both wild-type and mutated p110-alpha.

Title: Innate lymphoid cells mediate influenza-induced airway hyper-reactivity independently of adaptive immunity Content: Patients with asthma, a major public health problem, are at high risk for serious disease from influenza virus infection, but the pathogenic mechanisms by which influenza A causes airway disease and asthma are not fully known. We show here in a mouse model that influenza infection acutely induced airway hyper-reactivity (AHR), a cardinal feature of asthma, independently of T helper type 2 (TH2) cells and adaptive immunity. Instead, influenza infection induced AHR through a previously unknown pathway that required the interleukin 13 (IL-13)–IL-33 axis and cells of the non-T cell, non-B cell innate lymphoid type called 'natural helper cells'. Infection with influenza A virus, which activates the NLRP3 inflammasome, resulted in much more production of IL-33 by alveolar macrophages, which in turn activated natural helper cells producing substantial IL-13.

Title: The Proto-Oncogene c-maf Is Responsible for Tissue-Specific Expression of Interleukin-4 Content: The molecular basis for the distinctive cytokine expression of CD4+ T helper 1 (Th1) and T helper 2 (Th2) subsets remains elusive. Here, we report that the proto-oncogene c-maf, a basic region/leucine zipper transcription factor, controls tissue-specific expression of IL-4. c-Maf is expressed in Th2 but not Th1 clones and is induced during normal precursor cell differentiation along a Th2 but not Th1 lineage. c-Maf binds to a c-Maf response element (MARE) in the proximal IL-4 promoter adjacent to a site footprinted by extracts from Th2 but not Th1 clones. Ectopic expression of c-Maf transactivates the IL-4 promoter in Th1 cells, B cells, and nonlymphoid cells, a function that maps to the MARE and Th2-specific footprint. Furthermore, c-Maf acts in synergy with the nuclear factor of activated T cells (NF-ATp) to initiate endogeneous IL-4 production by B cells. Manipulation of c-Maf may alter Th subset ratios in human disease.

Title: Disease-associated functions of IL-33: the new kid in the IL-1 family Content: Interleukin-33 (IL-33), a newly described member of the IL-1 family, is expressed by many cell types following pro-inflammatory stimulation and is thought to be released on cell lysis. The IL-33 receptor, consisting of ST2 and IL-1 receptor accessory protein, is also widely expressed, particularly by T helper 2 (TH2) cells and mast cells. IL-33 is host-protective against helminth infection and reduces atherosclerosis by promoting TH2-type immune responses. However, IL-33 can also promote the pathogenesis of asthma by expanding TH2 cells and mediate joint inflammation, atopic dermatitis and anaphylaxis by mast cell activation. Thus IL-33 could be a new target for therapeutic intervention across a range of diseases.

Title: Genomic stability and tumour suppression by the APC/C cofactor Cdh1 Content: The anaphase promoting complex or cyclosome (APC/C) is a ubiquitin protein ligase that, together with Cdc20 or Cdh1, targets cell-cycle proteins for degradation. APC/C–Cdh1 specifically promotes protein degradation in late mitosis and G1. Mutant embryos lacking Cdh1 die at E9.5–E10.5 due to defects in the endoreduplication of trophoblast cells and placental malfunction. This lethality is prevented when Cdh1 is expressed in the placenta. Cdh1-deficient cells proliferate inefficiently and accumulate numeric and structural chromosomal aberrations, indicating that Cdh1 contributes to the maintenance of genomic stability. Cdh1 heterozygous animals show increased susceptibility to spontaneous tumours, suggesting that Cdh1 functions as a haploinsufficient tumour suppressor. These heterozygous mice also show several defects in behaviour associated with increased proliferation of stem cells in the nervous system. These results indicate that Cdh1 is required for preventing unscheduled proliferation of specific progenitor cells and protecting mammalian cells from genomic instability.

Title: Simian immunodeficiency viruses of diverse origin can use CXCR4 as a coreceptor for entry into human cells. Content: Primary simian immunodeficiency virus (SIV) isolated from sooty mangabey (SIVsm [n = 6]), stumptail (SIVstm [n = 1]), mandrill (SIVmnd [n = 1]), and African green (SIVagm [n = 1]) primates were examined for their ability to infect human cells and for their coreceptor requirements. All isolates infected human peripheral blood mononuclear cells (PBMCs) from a CCR5(+/+) donor, and seven of eight isolates tested also infected CCR5(-/-) PBMCs. Analysis of coreceptor utilization using GHOST and U87 cell lines revealed that all of the isolates tested used CCR5 and the orphan receptors STRL33 and GPR15. Coreceptors such as CCR2b, CCR3, CCR8, and CX3CR1 were also utilized by some primary SIV isolates. More importantly, we found that CXCR4 was used as a coreceptor by the SIVstm, the SIVagm, and four of the SIVsm isolates in GHOST and U87 cells. These data suggest that primary SIV isolates from diverse primate species can utilize CXCR4 for viral entry, similar to what has been described for human immunodeficiency viruses.

Title: Identification of secreted proteins that mediate cell-cell interactions in an in vitro model of the lung cancer microenvironment. Content: Non-small cell lung cancer (NSCLC) cells with somatic mutations in K-ras recruit to the tumor a variety of cell types (hereafter collectively termed "stromal cells") that can promote or inhibit tumorigenesis by mechanisms that have not been fully elucidated. Here, we postulated that stromal cells in the tumor microenvironment alter the tumor cell secretome, including those proteins required for tumor growth and dissemination, and we developed an in vitro model to test this hypothesis. Coculturing a murine K-ras mutant lung adenocarcinoma cell line (LKR-13) with a murine lung stromal cell (macrophage, endothelial cell, or fibroblast) enhanced stromal cell migration, induced endothelial tube formation, increased LKR-13 cell proliferation, and regulated the secretion of proteins involved in angiogenesis, inflammation, cell proliferation, and epithelial-to-mesenchymal transition. Among these proteins, CXCL1 has been reported to promote NSCLC development, whereas interleukin-18 (IL-18) has an undefined role. Genetic and pharmacologic strategies to inhibit CXCL1 and IL-18 revealed that stromal cell migration, LKR-13 cell proliferation, and LKR-13 cell tumorigenicity required one or both of these proteins. We conclude that stromal cells enhanced LKR-13 cell tumorigenicity partly through their effects on the secretome of LKR-13 cells. Strategies to inhibit tumor/stromal cell interactions may be useful as therapeutic approaches in NSCLC patients.

Title: Regulation of myeloid cell function through the CD200 receptor. Content: Myeloid cells play pivotal roles in chronic inflammatory diseases through their broad proinflammatory, destructive, and remodeling capacities. CD200 is widely expressed on a variety of cell types, while the recently identified CD200R is expressed on myeloid cells and T cells. CD200 deletion in vivo results in myeloid cell dysregulation and enhanced susceptibility to autoimmune inflammation, suggesting that the CD200-CD200R interaction is involved in immune suppression. We demonstrate in this study that CD200R agonists suppress mouse and human myeloid cell function in vitro, and also define a dose relationship between receptor expression and cellular inhibition. IFN-gamma- and IL-17-stimulated cytokine secretion from mouse peritoneal macrophages was inhibited by CD200R engagement. Inhibitory effects were not universal, as LPS-stimulated responses were unaffected. Inhibition of U937 cell cytokine production correlated with CD200R expression levels, and inhibition was only observed in low CD200R expressing cells, if the CD200R agonists were further cross-linked. Tetanus toxoid-induced human PBMC IL-5 and IL-13 secretion was inhibited by CD200R agonists. This inhibition was dependent upon cross-linking the CD200R on monocytes, but not on cross-linking the CD200R on CD4+ T cells. In all, we provide direct evidence that the CD200-CD200R interaction controls monocyte/macrophage function in both murine and human systems, further supporting the potential clinical application of CD200R agonists for the treatment of chronic inflammatory diseases.

Title: A systemic granulomatous response to Schistosoma mansoni eggs alters responsiveness of bone-marrow-derived macrophages to Toll-like receptor agonists. Content: Macrophages play a pivotal role in innate and acquired immune responses to Schistosoma mansoni. Classical (M1) or alternative (M2) activation states of these cells further delineate their roles in tissue damage through innate immunity or fibrotic remodeling, respectively. In the present study, we addressed the following question: Does systemic Th2-type cytokine polarization evoked by S. mansoni affect macrophage differentiation and activation? To this end, we analyzed bone marrow-derived macrophages from mice with S. mansoni egg-induced pulmonary granulomas and unchallenged (or naïve) mice to determine their activation state and their response to specific TLR agonists, including S. mansoni egg antigens. Unlike naïve macrophages, macrophages from Th2-polarized mice constitutively expressed significantly higher "found in inflammatory zone-1" (FIZZ1) and ST2 (M2 markers) and significantly lower NO synthase 2, CCL3, MIP-2, TNF-alpha, and IL-12 (M1 markers). Also, compared with naïve macrophages, Th2-polarized macrophages exhibited enhanced responses to the presence of specific TLR agonists, which consistently induced significantly higher levels of gene and protein levels for M2 and M1 markers in these cells. Together, these data show that signals received by bone marrow precursors during S. mansoni egg-induced granuloma responses dynamically alter the development of macrophages and enhance the TLR responsiveness of these cells, which may ultimately have a significant effect on the pulmonary granulomatous response.

Title: IL6 derived from cancer-associated fibroblasts promotes chemoresistance via CXCR7 in esophageal squamous cell carcinoma Content: Various factors and cellular components in the tumor microenvironment are key drivers associated with drug resistance in many cancers. Here, we analyzed the factors and molecular mechanisms involved in chemoresistance in patients with esophageal squamous cell carcinoma (ESCC). We found that interleukin 6 (IL6) derived mainly from cancer-associated fibroblasts played the most important role in chemoresistance by upregulating C-X-C motif chemokine receptor 7 (CXCR7) expression through signal transducer and activator of transcription 3/nuclear factor-κB pathway. CXCR7 knockdown resulted in the inhibition of IL6-induced proliferation and chemoresistance. In addition, CXCR7 silencing significantly decreased gene expression associated with stemness, chemoresistance and epithelial–mesenchymal transition and suppressed the proliferation ability of ESCC cells in three-dimensional culture systems and angiogenesis assay. In clinical samples, ESCC patients with high expression of CXCR7 and IL6 presented a significantly worse overall survival and progression-free survival upon receiving cisplatin after operation. These results suggest that the IL6–CXCR7 axis may provide a promising target for the treatment of ESCC.

Title: Memory CD4+ T cells induce innate responses independently of pathogen Content: Inflammation induced by recognition of pathogen-associated molecular patterns markedly affects subsequent adaptive responses. We asked whether the adaptive immune system can also affect the character and magnitude of innate inflammatory responses. We found that the response of memory, but not naive, CD4+ T cells enhances production of multiple innate inflammatory cytokines and chemokines (IICs) in the lung and that, during influenza infection, this leads to early control of virus. Memory CD4+ T cell–induced IICs and viral control require cognate antigen recognition and are optimal when memory cells are either T helper type 1 (TH1) or TH17 polarized but are independent of interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) production and do not require activation of conserved pathogen recognition pathways. This represents a previously undescribed mechanism by which memory CD4+ T cells induce an early innate response that enhances immune protection against pathogens.

Title: Integrin αvβ8-Mediated TGF-β Activation by Effector Regulatory T Cells Is Essential for Suppression of T-Cell-Mediated Inflammation Content: Regulatory T (Treg) cells play a pivotal role in suppressing self-harmful T cell responses, but how Treg cells mediate suppression to maintain immune homeostasis and limit responses during inflammation is unclear. Here we show that effector Treg cells express high amounts of the integrin αvβ8, which enables them to activate latent transforming growth factor-β (TGF-β). Treg-cell-specific deletion of integrin αvβ8 did not result in a spontaneous inflammatory phenotype, suggesting that this pathway is not important in Treg-cell-mediated maintenance of immune homeostasis. However, Treg cells lacking expression of integrin αvβ8 were unable to suppress pathogenic T cell responses during active inflammation. Thus, our results identify a mechanism by which Treg cells suppress exuberant immune responses, highlighting a key role for effector Treg-cell-mediated activation of latent TGF-β in suppression of self-harmful T cell responses during active inflammation.

Title: A crucial role for interleukin (IL)-1 in the induction of IL-17–producing T cells that mediate autoimmune encephalomyelitis Content: It was recently demonstrated that interleukin (IL)-23–driven IL-17–producing (ThIL-17) T cells mediate inflammatory pathology in certain autoimmune diseases. We show that the induction of antigen-specific ThIL-17 cells, but not T helper (Th)1 or Th2 cells, by immunization with antigens and adjuvants is abrogated in IL-1 receptor type I–deficient (IL-1RI−/−) mice. Furthermore, the incidence of experimental autoimmune encephalomyelitis (EAE) was significantly lower in IL-1RI−/− compared with wild-type mice, and this correlated with a failure to induce autoantigen-specific ThIL-17 cells, whereas induction of Th1 and Th2 responses was not substantially different. However, EAE was induced in IL-1RI−/− mice by adoptive transfer of autoantigen-specific cells from wild-type mice with EAE. IL-23 alone did not induce IL-17 production by T cells from IL-1RI−/− mice, and IL-23–induced IL-17 production was substantially enhanced by IL-1α or IL-1β, even in the absence of T cell receptor stimulation. We demonstrate essential roles for phosphatidylinositol 3-kinase, nuclear factor κB, and novel protein kinase C isoforms in IL-1– and IL-23–mediated IL-17 production. Tumor necrosis factor α also synergized with IL-23 to enhance IL-17 production, and this was IL-1 dependent. Our findings demonstrate that IL-1 functions upstream of IL-17 to promote pathogenic ThIL-17 cells in EAE.

Title: Chemokine-like receptor 1 (CMKLR1) and chemokine (C-C motif) receptor-like 2 (CCRL2); two multifunctional receptors with unusual properties. Content: Chemokine-like receptor 1 (CMKLR1), also known as ChemR23, and chemokine (C-C motif) receptor-like 2 (CCRL2) are 7-transmembrane receptors that were cloned in the late 1990s based on their homology to known G-protein-coupled receptors. They were previously orphan receptors without any known biological roles; however, recent studies identified ligands for these receptors and their functions have begun to be unveiled. The plasma protein-derived chemoattractant chemerin is a ligand for CMKLR1 and activation of CMKLR1 with chemerin induces the migration of macrophages and dendritic cells (DCs) in vitro, suggesting a proinflammatory role. However, in vivo studies using CMKLR-deficient mice suggest an anti-inflammatory role for this receptor, possibly due to the recruitment of tolerogenic plasmacytoid DCs. Chemerin/CMKLR1 interaction also promotes adipogenesis and angiogenesis. The anti-inflammatory lipid mediator, resolving E1, is another CMKLR1 ligand and it inhibits leukocyte infiltration and proinflammatory gene expression. These divergent results suggest that CMKLR1 is a multifunctional receptor. The chemokine CCL5 and CCL19 are reported to bind to CCRL2. Like Duffy antigen for chemokine receptor (DARC), D6 and CCX-CKR, CCRL2 does not signal, but it constitutively recycles, potentially reducing local concentration of CCL5 and CCL19 and subsequent immune responses. Surprisingly, chemerin, a ligand for CMKLR1, is a ligand for CCRL2. CCRL2 binds chemerin and increases local chemerin concentration to efficiently present it to CMKLR1 on nearby cells, providing a link between CCRL2 and CMKLR1. Although these findings suggest an anti-inflammatory role, a recent study using CCRL2-deficient mice indicates a proinflammatory role; thus, CCRL2 may also be multifunctional. Further studies using CMKLR1- or CCRL2-deficient mice are needed to further define the role of these receptors in immune responses and other cellular processes.

Title: Thioredoxin mediates oxidation-dependent phosphorylation of CRMP2 and growth cone collapse. Content: Semaphorin3A (Sema3A) is a repulsive guidance molecule for axons, which acts by inducing growth cone collapse through phosphorylation of CRMP2 (collapsin response mediator protein 2). Here, we show a role for CRMP2 oxidation and thioredoxin (TRX) in the regulation of CRMP2 phosphorylation and growth cone collapse. Sema3A stimulation generated hydrogen peroxide (H2O2) through MICAL (molecule interacting with CasL) and oxidized CRMP2, enabling it to form a disulfide-linked homodimer through cysteine-504. Oxidized CRMP2 then formed a transient disulfide-linked complex with TRX, which stimulated CRMP2 phosphorylation by glycogen synthase kinase-3, leading to growth cone collapse. We also reconstituted oxidation-dependent phosphorylation of CRMP2 in vitro, using a limited set of purified proteins. Our results not only clarify the importance of H2O2 and CRMP2 oxidation in Sema3A-induced growth cone collapse but also indicate an unappreciated role for TRX in linking CRMP2 oxidation to phosphorylation.

Title: CCR6 regulates the migration of inflammatory and regulatory T cells. Content: Th17 and regulatory T (Treg) cells play opposite roles in autoimmune diseases. However, the mechanisms underlying their proper migration to inflammatory tissues are unclear. In this study, we report that these two T cell subsets both express CCR6. CCR6 expression in Th17 cells is regulated by TGF-beta and requires two nuclear receptors, RORalpha and RORgamma. Th17 cells also express the CCR6 ligand CCL20, which is induced synergistically by TGF-beta and IL-6, which requires STAT3, RORgamma and IL-21. Th17 cells, by producing CCL20, promote migration of Th17 and Treg cells in vitro in a CCR6-dependent manner. Lack of CCR6 in Th17 cells reduces the severity of experimental autoimmune encephalomyelitis and Th17 and Treg recruitment into inflammatory tissues. Similarly, CCR6 on Treg cells is also important for their recruitment into inflammatory tissues. Our data indicate an important role of CCR6 in Treg and Th17 cell migration.

Title: Retinal attenuates inflammatory arthritis by reciprocal regulation of IL-17-producing T cells and Foxp3(+) regulatory T cells and the inhibition of osteoclastogenesis. Content: Retinoids (e.g., vitamin A and its derivatives) can regulate immune responses. The aim of this study was to determine whether all-trans retinaldehyde (retinal), a vitamin A derivative, can inhibit inflammatory responses and joint destruction in DBA/1J mice with collagen-induced arthritis (CIA). The arthritis score and incidence of arthritis were lower in mice treated with retinal compared to those treated with cottonseed oil. Histopathologic evidence of joint damage was lower in mice treated with retinal, corresponding with a reduction in the infiltration of immune cells in mice treated with retinal type II collagen (CII)-stimulated spleen cells. In addition, the expression of proinflammatory cytokines, oxidative stress proteins, and osteoclast markers were significantly reduced in mice treated with retinal. In vitro, retinal induced increased Foxp3 expression and inhibited Th17 development. The proportion of Foxp3(+) Treg cells was increased in the spleens of mice treated with retinal, whereas the proportion of Th17 cells was reduced. In both mice and a human culture system, tartrate-resistant acid phosphatase (TRAP) positive mononuclear cells and multinucleated cells were significantly reduced after treatment with retinal. The expression of osteoclast differentiation markers was dramatically decreased upon addition of retinal. This is the first study to demonstrate the therapeutic effect of retinal on an autoimmune arthritis model in mice through reciprocal regulation of Th17 and regulatory T cells and protection of differentiation and activation of osteoclasts. Taken together, our findings indicate that retinal has profound immunoregulatory functions and potential value for the treatment of autoimmune inflammatory disorders.

Title: The transcription factor c-Maf controls the production of interleukin-4 but not other Th2 cytokines. Content: IL-4 promotes the differentiation of naive CD4+ T cells into IL-4-producing T helper 2 (Th2) cells. Previous work provided suggestive but not conclusive evidence that the transcription factor c-Maf directed the tissue-specific expression of IL-4. It was not known whether c-Maf controlled the transcription of other Th2 cytokine genes. To elucidate the role of c-Maf in vivo, we examined cytokine production in mice lacking c-Maf (c-maf(-/-)). CD4+ T cells and NK T cells from c-maf(-/-) mice were markedly deficient in IL-4 production. However, the mice produced normal levels of IL-13 and IgE, and, when differentiated in the presence of exogenous IL-4, c-maf(-/-) T cells produced approximately normal levels of other Th2 cytokines. We conclude that c-Maf has a critical and selective function in IL-4 gene transcription in vivo.

Title: Role of ocular pigment epithelial cells in immune privilege Content: The ocular microenvironment is both immunosuppressive and anti-inflammatory in nature. Pigment epithelial (PE) cells isolated from the eye possess the ability to suppress the T cell receptor-dependent activation of T cells and the induction of regulatory T cells in vitro. This property is dependent on the cells’ capacity to produce cell-surface and soluble inhibitory molecules, for example CD86 (B7-2), transforming growth factor (TGF)-β, thrombospondin-1, programmed cell death 1 ligand 1 (PD-L1/B7-H1), and cytotoxic T lymphocyte-associated antigen 2α. Cultured ocular PE cells from the iris, ciliary body, and retina can individually suppress T-cell activation via mechanisms that partially overlap. Moreover, PE-derived regulatory T cells acquire functions that play a role in establishing immune regulation in the eye. Multiple strategies are employed within the eye to control immune-mediated inflammation. This phenomenon is known as immune privilege and is instrumental in helping to prevent extensive damage to bystander cells that would otherwise lead to blindness. This review focuses on the immunosuppressive property and role of ocular PE cells in immune privileged sites.

Title: Blimp-1 attenuates Th1 differentiation by repression of ifng, tbx21, and bcl6 gene expression. Content: T cell-specific deletion of Blimp-1 causes abnormal T cell homeostasis and function, leading to spontaneous, fatal colitis in mice. Herein we explore the role of Blimp-1 in Th1/Th2 differentiation. Blimp-1 mRNA and protein are more highly expressed in Th2 cells compared with Th1 cells, and Blimp-1 attenuates IFN-gamma production in CD4 cells activated under nonpolarizing conditions. Although Blimp-1-deficient T cells differentiate normally to Th2 cytokines in vitro, Blimp-1 is required in vivo for normal Th2 humoral responses to NP-KLH (4-hydroxy-3-nitrophenylacetyl/keyhole lymphocyte hemocyanin) immunization. Lack of Blimp-1 in CD4 T cells causes increased IFN-gamma, T-bet, and Bcl-6 mRNA. By chromatin immunoprecipitation we show that Blimp-1 binds directly to a distal regulatory region in the ifng gene and at multiple sites in tbx21 and bcl6 genes. Our data provide evidence that Blimp-1 functions in Th2 cells to reinforce Th2 differentiation by repressing critical Th1 genes.

Title: Ncf1 (p47phox) Is Essential for Direct Regulatory T Cell Mediated Suppression of CD4+ Effector T Cells Content: BACKGROUND Multiple mechanisms have been advanced to account for CD4+FOXP3+ regulatory T cell (Treg)-mediated suppression of CD4+ effector T cells (Teffs) but none appear to completely explain suppression. Previous data indicates that Tregs may affect the microenvironment redox state. Given the inherent redox sensitivity of T cells, we tested the hypothesis that oxidants may mediate the direct suppression of Teffs by Tregs. METHODOLOGY/PRINCIPAL FINDINGS Tregs and Teffs were isolated from the spleens of wild type (WT) C57BL/6 mice or Ncf1(p47phox)-deficient C57BL/6 mice which lack NADPH oxidase function. Teffs were labeled with CFSE and co-cultured with unlabeled Tregs at varying Treg:Teff ratios in the presence of anti-CD3/CD28 coated beads for 3 days in suppression assays. Treg-mediated suppression was quantified by flow cytometric analysis of CFSE dilution in Teffs. The presence of the antioxidants n-acetylcysteine (NAC) or 2-mercaptoethanol or inhibitors of NADPH oxidase (diphenyleneiodonium and VAS-2870) resulted in reduced WT Treg-mediated suppression. The observed suppression was in part dependent upon TGFβ as it was partially blocked with neutralizing antibodies. The suppression of Teff proliferation induced by exogenous TGFβ treatment could be overcome with NAC. Ncf1-deficient Teff were slightly but significantly less sensitive than WT Teff to suppression by exogenous TGFβ. Ncf1-deficient Tregs suppressed Ncf1-deficient Teff very poorly compared to wild type controls. There was partial but incomplete reconstitution of suppression in assays with WT Tregs and Ncf1-deficient Teff. CONCLUSIONS/SIGNIFICANCE We present evidence that NADPH oxidase derived ROS plays a role in the direct Treg mediated suppression of CD4+ effector T cells in a process that is blocked by thiol-containing antioxidants, NADPH oxidase inhibitors or a lack of Ncf1 expression in Tregs and Teffs. Oxidants may represent a potential new target for therapeutic modulation of Treg function.

Title: Sestrin2 inhibits uncoupling protein 1 expression through suppressing reactive oxygen species. Content: Uncoupling protein 1 (Ucp1), which is localized in the mitochondrial inner membrane of mammalian brown adipose tissue (BAT), generates heat by uncoupling oxidative phosphorylation. Upon cold exposure or nutritional abundance, sympathetic neurons stimulate BAT to express Ucp1 to induce energy dissipation and thermogenesis. Accordingly, increased Ucp1 expression reduces obesity in mice and is correlated with leanness in humans. Despite this significance, there is currently a limited understanding of how Ucp1 expression is physiologically regulated at the molecular level. Here, we describe the involvement of Sestrin2 and reactive oxygen species (ROS) in regulation of Ucp1 expression. Transgenic overexpression of Sestrin2 in adipose tissues inhibited both basal and cold-induced Ucp1 expression in interscapular BAT, culminating in decreased thermogenesis and increased fat accumulation. Endogenous Sestrin2 is also important for suppressing Ucp1 expression because BAT from Sestrin2(-/-) mice exhibited a highly elevated level of Ucp1 expression. The redox-inactive mutant of Sestrin2 was incapable of regulating Ucp1 expression, suggesting that Sestrin2 inhibits Ucp1 expression primarily through reducing ROS accumulation. Consistently, ROS-suppressing antioxidant chemicals, such as butylated hydroxyanisole and N-acetylcysteine, inhibited cold- or cAMP-induced Ucp1 expression as well. p38 MAPK, a signaling mediator required for cAMP-induced Ucp1 expression, was inhibited by either Sestrin2 overexpression or antioxidant treatments. Taken together, these results suggest that Sestrin2 and antioxidants inhibit Ucp1 expression through suppressing ROS-mediated p38 MAPK activation, implying a critical role of ROS in proper BAT metabolism.

Title: Hypoxia-induced energy stress regulates mRNA translation and cell growth. Content: Oxygen (O2) deprivation, or hypoxia, has profound effects on cell metabolism and growth. Cells can adapt to low O2 in part through activation of hypoxia-inducible factor (HIF). We report here that hypoxia inhibits mRNA translation by suppressing multiple key regulators, including eIF2alpha, eEF2, and the mammalian target of rapamycin (mTOR) effectors 4EBP1, p70S6K, and rpS6, independent of HIF. Hypoxia results in energy starvation and activation of the AMPK/TSC2/Rheb/mTOR pathway. Hypoxic AMP-activated protein kinase (AMPK) activation also leads to eEF2 inhibition. Moreover, hypoxic effects on cellular bioenergetics and mTOR inhibition increase over time. Mutation of the TSC2 tumor suppressor gene confers a growth advantage to cells by repressing hypoxic mTOR inhibition and hypoxia-induced G1 arrest. Together, eIF2alpha, eEF2, and mTOR inhibition represent important HIF-independent mechanisms of energy conservation that promote survival under low O2 conditions.

Title: Novel Foxo1-dependent transcriptional programs control Treg cell function Content: Regulatory T (Treg) cells, characterized by expression of the transcription factor forkhead box P3 (Foxp3), maintain immune homeostasis by suppressing self-destructive immune responses. Foxp3 operates as a late-acting differentiation factor controlling Treg cell homeostasis and function, whereas the early Treg-cell-lineage commitment is regulated by the Akt kinase and the forkhead box O (Foxo) family of transcription factors. However, whether Foxo proteins act beyond the Treg-cell-commitment stage to control Treg cell homeostasis and function remains largely unexplored. Here we show that Foxo1 is a pivotal regulator of Treg cell function. Treg cells express high amounts of Foxo1 and display reduced T-cell-receptor-induced Akt activation, Foxo1 phosphorylation and Foxo1 nuclear exclusion. Mice with Treg-cell-specific deletion of Foxo1 develop a fatal inflammatory disorder similar in severity to that seen in Foxp3-deficient mice, but without the loss of Treg cells. Genome-wide analysis of Foxo1 binding sites reveals ∼300 Foxo1-bound target genes, including the pro-inflammatory cytokine Ifng, that do not seem to be directly regulated by Foxp3. These findings show that the evolutionarily ancient Akt–Foxo1 signalling module controls a novel genetic program indispensable for Treg cell function.

Title: Dual role of the IL-12/IFN-gamma axis in the development of autoimmune myocarditis: induction by IL-12 and protection by IFN-gamma. Content: IL-12 and IFN-gamma positively regulate each other and type 1 inflammatory responses, which are believed to cause tissue damage in autoimmune diseases. We investigated the role of the IL-12/IFN-gamma (Th1) axis in the development of autoimmune myocarditis. IL-12p40-deficient mice on a susceptible background resisted myocarditis. In the absence of IL-12, autospecific CD4(+) T cells proliferated poorly and showed increased Th2 cytokine responses. However, IFN-gamma-deficient mice developed fatal autoimmune disease, and blockade of IL-4R signaling did not confer susceptibility to myocarditis in IL-12p40-deficient mice, demonstrating that IL-12 triggers autoimmunity by a mechanism independent of the effector cytokines IFN-gamma and IL-4. In conclusion, our results suggest that the IL-12/IFN-gamma axis is a double-edged sword for the development of autoimmune myocarditis. Although IL-12 mediates disease by induction/expansion of Th1-type cells, IFN-gamma production from these cells limits disease progression.

Title: Differential role of CbpA and PspA in modulation of in vitro CXC chemokine responses of respiratory epithelial cells to infection with Streptococcus pneumoniae. Content: Respiratory epithelial cells play an active part in the host response to respiratory pathogens, such as Streptococcus pneumoniae, by releasing chemokines responsible for neutrophil recruitment. In order to investigate the role of specific pneumococcal virulence factors in eliciting CXC chemokine responses, type II pneumocytes (A549) and nasopharyngeal cells (Detroit-562) were infected with S. pneumoniae D39 or mutants lacking choline-binding protein A (CbpA), pneumococcal surface protein A (PspA), or specific domains thereof. In response to wild-type D39, both A549 and Detroit-562 cells showed a significant increase in CXC chemokine mRNA and interleukin-8 protein. This response was increased twofold when a cbpA deletion mutant (DeltaCbpA) was used, suggesting that CbpA inhibits CXC chemokine induction. All three N-terminal domains of CbpA are required for this effect, as in-frame deletion of the respective region of cbpA had the same effect on the CXC chemokine response as deletion of cbpA altogether. Infection with a pspA deletion mutant (DeltaPspA) led to a twofold decrease in the CXC chemokine response of A549 but not Detroit-562 cells, compared to infection with D39 at 2 h. Thus, PspA appears to have the ability to stimulate early CXC chemokine release from A549 cells. Deletion of the region of pspA encoding the first N-terminal alpha-helical domain reduced the ability of S. pneumoniae to elicit a chemokine response to the same degree as deletion of pspA altogether. Thus, the N termini of CbpA and PspA exert differential effects on CXC chemokine induction in epithelial cells infected with S. pneumoniae.

Title: Functional in vivo interactions between JNK1 and JNK2 isoforms in obesity and insulin resistance. Content: The c-Jun N-terminal kinases (JNKs) are key regulators of inflammation and interfere with insulin action in cultured cells and whole animals. Obesity increases total JNK activity, and JNK1, but not JNK2, deficiency results in reduced adiposity and improved insulin sensitivity. Interestingly, a higher-than-normal level of JNK activation is observed in Jnk2(-/-) mice, particularly in the liver, indicating an interaction between the isoforms that might have masked the metabolic activity of JNK2 in isolated mutant mice. To address the role of the JNK2 isoform in metabolic homeostasis, we intercrossed Jnk1(-/-) and Jnk2(-/-) mice and examined body weight and glucose metabolism in the resulting mutant allele combinations. Among all of the viable genotypes examined, we observed only reduced body weight and increased insulin sensitivity in Jnk1(-/-) and Jnk1(+/-)Jnk2(-/-) mice. These two groups of mice also exhibited reduced total JNK activity and cytokine expression in liver tissue compared with all other genotypes examined. These data indicate that the JNK2 isoform is also involved in metabolic regulation, but its function is not obvious when JNK1 is fully expressed because of regulatory crosstalk between the two isoforms.

Title: Invariant NKT cells modulate the suppressive activity of IL-10-secreting neutrophils differentiated with serum amyloid A. Content: Neutrophils are the main effector cells during inflammation, but they can also control excessive inflammatory responses by secreting anti-inflammatory cytokines. However, the mechanisms that modulate their plasticity remain unclear. We now show that systemic serum amyloid A 1 (SAA-1) controls the plasticity of neutrophil differentiation. SAA-1 not only induced anti-inflammatory interleukin 10 (IL-10)-secreting neutrophils but also promoted the interaction of invariant natural killer T cells (iNKT cells) with those neutrophils, a process that limited their suppressive activity by diminishing the production of IL-10 and enhancing the production of IL-12. Because SAA-1-producing melanomas promoted differentiation of IL-10-secreting neutrophils, harnessing iNKT cells could be useful therapeutically by decreasing the frequency of immunosuppressive neutrophils and restoring tumor-specific immune responses.

Title: BH3-only Protein Noxa Is a Mediator of Hypoxic Cell Death Induced by Hypoxia-inducible Factor 1α Content: Hypoxia is a common cause of cell death and is implicated in many disease processes including stroke and chronic degenerative disorders. In response to hypoxia, cells express a variety of genes, which allow adaptation to altered metabolic demands, decreased oxygen demands, and the removal of irreversibly damaged cells. Using polymerase chain reaction–based suppression subtractive hybridization to find genes that are differentially expressed in hypoxia, we identified the BH3-only Bcl-2 family protein Noxa. Noxa is a candidate molecule mediating p53-induced apoptosis. We show that Noxa promoter responds directly to hypoxia via hypoxia-inducible factor (HIF)-1α. Suppression of Noxa expression by antisense oligonucleotides rescued cells from hypoxia-induced cell death and decreased infarction volumes in an animal model of ischemia. Further, we show that reactive oxygen species and resultant cytochrome c release participate in Noxa-mediated hypoxic cell death. Altogether, our results show that Noxa is induced by HIF-1α and mediates hypoxic cell death.

Title: Regulated Accumulation of Desmosterol Integrates Macrophage Lipid Metabolism and Inflammatory Responses Content: Inflammation and macrophage foam cells are characteristic features of atherosclerotic lesions, but the mechanisms linking cholesterol accumulation to inflammation and LXR-dependent response pathways are poorly understood. To investigate this relationship, we utilized lipidomic and transcriptomic methods to evaluate the effect of diet and LDL receptor genotype on macrophage foam cell formation within the peritoneal cavities of mice. Foam cell formation was associated with significant changes in hundreds of lipid species and unexpected suppression, rather than activation, of inflammatory gene expression. We provide evidence that regulated accumulation of desmosterol underlies many of the homeostatic responses, including activation of LXR target genes, inhibition of SREBP target genes, selective reprogramming of fatty acid metabolism, and suppression of inflammatory-response genes, observed in macrophage foam cells. These observations suggest that macrophage activation in atherosclerotic lesions results from extrinsic, proinflammatory signals generated within the artery wall that suppress homeostatic and anti-inflammatory functions of desmosterol.

Title: Cyclooxygenase-Dependent Tumor Growth through Evasion of Immunity Content: The mechanisms by which melanoma and other cancer cells evade anti-tumor immunity remain incompletely understood. Here, we show that the growth of tumors formed by mutant Braf(V600E) mouse melanoma cells in an immunocompetent host requires their production of prostaglandin E2, which suppresses immunity and fuels tumor-promoting inflammation. Genetic ablation of cyclooxygenases (COX) or prostaglandin E synthases in Braf(V600E) mouse melanoma cells, as well as in Nras(G12D) melanoma or in breast or colorectal cancer cells, renders them susceptible to immune control and provokes a shift in the tumor inflammatory profile toward classic anti-cancer immune pathways. This mouse COX-dependent inflammatory signature is remarkably conserved in human cutaneous melanoma biopsies, arguing for COX activity as a driver of immune suppression across species. Pre-clinical data demonstrate that inhibition of COX synergizes with anti-PD-1 blockade in inducing eradication of tumors, implying that COX inhibitors could be useful adjuvants for immune-based therapies in cancer patients.

Title: Amphiregulin enhances regulatory T cell-suppressive function via the epidermal growth factor receptor. Content: Epidermal growth factor receptor (EGFR) is known to be critically involved in tissue development and homeostasis as well as in the pathogenesis of cancer. Here we showed that Foxp3(+) regulatory T (Treg) cells express EGFR under inflammatory conditions. Stimulation with the EGF-like growth factor Amphiregulin (AREG) markedly enhanced Treg cell function in vitro, and in a colitis and tumor vaccination model we showed that AREG was critical for efficient Treg cell function in vivo. In addition, mast cell-derived AREG fully restored optimal Treg cell function. These findings reveal EGFR as a component in the regulation of local immune responses and establish a link between mast cells and Treg cells. Targeting of this immune regulatory mechanism may contribute to the therapeutic successes of EGFR-targeting treatments in cancer patients.

Title: Caveolin-1 deletion exacerbates cardiac interstitial fibrosis by promoting M2 macrophage activation in mice after myocardial infarction. Content: Adverse remodeling following myocardial infarction (MI) leading to heart failure is driven by an imbalanced resolution of inflammation. The macrophage cell is an important control of post-MI inflammation, as macrophage subtypes secrete mediators to either promote inflammation and extend injury (M1 phenotype) or suppress inflammation and promote scar formation (M2 phenotype). We have previously shown that the absence of caveolin-1 (Cav1), a membrane scaffolding protein, is associated with adverse cardiac remodeling in mice, but the mechanisms responsible remain to be elucidated. We explore here the role of Cav1 in the activation of macrophages using wild type C57BL6/J (WT) and Cav1(tm1Mls/J) (Cav1(-/-)) mice. By echocardiography, cardiac function was comparable between WT and Cav1(-/-) mice at 3days post-MI. In the absence of Cav1, there were a surprisingly higher percentage of M2 macrophages (arginase-1 positive) detected in the infarcted zone. Conversely, restoring Cav1 function after MI in WT mice by adding back the Cav1 scaffolding domain reduced the M2 activation profile. Further, adoptive transfer of Cav1 null macrophages into WT mice on d3 post-MI exacerbated adverse cardiac remodeling at d14 post-MI. In vitro studies revealed that Cav1 null macrophages had a more pronounced M2 profile activation in response to IL-4 stimulation. In conclusion, Cav1 deletion promotes an array of maladaptive repair processes after MI, including increased TGF-β signaling, increased M2 macrophage infiltration and dysregulation of the M1/M2 balance. Our data also suggest that cardiac remodeling can be improved by therapeutic intervention regulating Cav1 function during the inflammatory response phase.

Title: LincRNA-p21 suppresses target mRNA translation. Content: Mammalian long intergenic noncoding RNAs (lincRNAs) are best known for modulating transcription. Here we report a posttranscriptional function for lincRNA-p21 as a modulator of translation. Association of the RNA-binding protein HuR with lincRNA-p21 favored the recruitment of let-7/Ago2 to lincRNA-p21, leading to lower lincRNA-p21 stability. Under reduced HuR levels, lincRNA-p21 accumulated in human cervical carcinoma HeLa cells, increasing its association with JUNB and CTNNB1 mRNAs and selectively lowering their translation. With elevated HuR, lincRNA-p21 levels declined, which in turn derepressed JunB and β-catenin translation and increased the levels of these proteins. We propose that HuR controls translation of a subset of target mRNAs by influencing lincRNA-p21 levels. Our findings uncover a role for lincRNA as a posttranscriptional inhibitor of translation.

Title: Role of the CXCR4/SDF-1 chemokine axis in circulating neutrophil homeostasis. Content: The bone marrow is the primary site for neutrophil production and release into the circulation. Because the CXC chemokine receptor-4/stromal derived factor-1 (CXCR4/SDF-1) axis plays a central role in the interactions of hematopoietic stem cells, lymphocytes, and developing neutrophils in the marrow, we investigated whether reciprocal CXCR4-dependent mechanisms might be involved in neutrophil release and subsequent return to the marrow following circulation. Neutralizing antibody to CXCR4 reduced marrow retention of infused neutrophils (45.7% +/- 0.5% to 6.9% +/- 0.5%) and was found to mobilize neutrophils from marrow (34.4% +/- 4.4%). Neutrophil CXCR4 expression and SDF-1-induced calcium flux decreased with maturation and activation of the cells, corresponding to the decreased marrow homing associated with these characteristics in vivo. Infusion of the inflammatory mediator and CXCR2 ligand KC led to mobilization of neutrophils from marrow by itself and was augmented 3-fold by low doses of CXCR4-blocking antibody that otherwise had no mobilizing effect. Examination of KC and SDF-1 calcium signaling demonstrated that the effect of KC may, in part, be due to heterologous desensitization to SDF-1. These results suggest that the CXCR4/SDF-1 axis is critical in circulating neutrophil homeostasis and that it may participate in the rapid release of neutrophils from the marrow during inflammation through a novel interaction with inflammatory CXC chemokines.

Title: Non-canonical PI3K-Cdc42-Pak-Mek-Erk Signaling Promotes Immune-Complex-Induced Apoptosis in Human Neutrophils Content: Neutrophils are peripheral blood leukocytes that represent the first line of immune cell defense against bacterial and fungal infections but are also crucial players in the generation of the inflammatory response. Many neutrophil cell surface receptors regulate important cellular processes via activation of agonist-activated PI3Ks. We show here that activation of human neutrophils with insoluble immune complexes drives a previously uncharacterized, PI3K-dependent, non-canonical, pro-apoptotic signaling pathway, FcγR-PI3Kβ/δ-Cdc42-Pak-Mek-Erk. This is a rare demonstration of Ras/Raf-independent activation of Erk and of PI3K-mediated activation of Cdc42. In addition, comparative analysis of immune-complex- and fMLF-induced signaling uncovers key differences in pathways used by human and murine neutrophils. The non-canonical pathway we identify in this study may be important for the resolution of inflammation in chronic inflammatory diseases that rely on immune-complex-driven neutrophil activation.

Title: Dual role of interleukin-10 in the regulation of respiratory syncitial virus (RSV)-induced lung inflammation. Content: RSV lower respiratory tract infections (LRTI) are among the most common diseases necessitating hospital admission in children. In addition to causing acute respiratory failure, RSV infections are associated with sequelae such as secondary bacterial infections and reactive airway disease. One characteristic host response observed in severe RSV-induced LRTI and/or subsequent development of asthma is increased expression of interleukin (IL)-10. However, contradictory results have been reported regarding whether IL-10 inhibits asthmatic responses or intensifies the disease. We aimed to reconcile these discordant observations by elucidating the role of IL-10 in regulating the host response to RSV LRTI. In this study, we used a lung-specific, inducible IL-10 over-expression (OE) transgenic mouse model to address this question. Our results showed that the presence of IL-10 at the time of RSV infection not only attenuated acute inflammatory process (i.e. 24 h post-infection), but also late inflammatory changes [characterized by T helper type 2 (Th2) cytokine and chemokine expression]. While this result appears contradictory to some clinical observations where elevated IL-10 levels are observed in asthmatic patients, we also found that delaying IL-10 OE until the late immune response to RSV infection, additive effects rather than inhibitory effects were observed. Importantly, in non-infected, IL-10 OE mice, IL-10 OE alone induced up-regulation of Th2 cytokine (IL-13 and IL-5) and Th2-related chemokine [monocyte chemoattractant protein 1 (MCP-1), chemokine (C-C motif) ligand 3 (CCL3) and regulated upon activation normal T cell expressed and secreted (RANTES)] expression. We identified a subset of CD11b(+)CD11c(+)CD49b(+)F4/80(-)Gr-1(-) myeloid cells as a prinicipal source of IL-10-induced IL-13 production. Therefore, the augmented pathological responses observed in our 'delayed' IL-10 over-expression model could be attributed to IL-10 OE alone. Taken together, our study indicated dual roles of IL-10 on RSV-induced lung inflammation which appear to depend upon the timing of when elevated IL-10 is expressed in the lung.

Title: Ca2+-permeable AMPA receptors regulate growth of human glioblastoma via Akt activation. Content: Evidence has been accumulated that glioblastoma cells release and exploit glutamate for proliferation and migration by autocrine or paracrine loops through Ca2+-permeable AMPA-type glutamate receptors. Here, we show that Ca2+ signaling mediated by AMPA receptor regulates the growth and motility of glioblastoma cells via activation of Akt. Ca2+ supplied through Ca2+-permeable AMPA receptor phosphorylated Akt at Ser-473, thereby facilitating proliferation and mobility. A dominant-negative form of Akt inhibited cell proliferation and migration accelerated by overexpression of Ca2+-permeable AMPA receptor. In contrast, introduction of a constitutively active form of Akt rescued tumor cells from apoptosis induced by the conversion of Ca2+-permeable AMPA receptor to Ca2+-impermeable receptors by the delivery of GluR2 cDNA. Therefore, Akt functions as downstream effectors for Ca2+-signaling mediated by AMPA receptor in glioblastoma cells. The activation of the glutamate-AMPA receptor-Akt pathway may contribute to the high degree of anaplasia and invasive growth of human glioblastoma. This novel pathway might give an alternative therapeutic target.

Title: Targeted blockade of TGF-β and IL-6/JAK2/STAT3 pathways inhibits lung cancer growth promoted by bone marrow-derived myofibroblasts Content: To investigate the role of TGF-β and IL-6 in myofibroblasts (MFs) - lung cancer cell interactions, lung cancer cells (Lewis and CTM-167 cell lines) were stimulated by IL-6, MF-conditioned medium (MF-CM) or MFs, with or without TGF-β signaling inhibitor - SB431542 and/or JAK2/STAT3 inhibitor - JSI-124. MFs were stimulated by TGF-β, cancer cell-CM or cancer cells, with or without SB431542 and JSI-124. Cell proliferation, the levels of cytokines, expression of mRNA and protein were determined. Mice bearing xenograft tumors were intraperitoneally treated with SB431542 or JSI-124 and monitored for up to 45 days. In co-culture systems, MFs secreted high levels of IL-6, while cancer cells produced high levels of TGF-β. Recombinant IL-6 and MF-CM activated STAT3 and upregulated TGF-β in cancer cells. In contrast, cancer cell-CM or TGF-β stimulated MFs to produce IL-6. Blockade of JAK2/STAT3 and TGF-β signaling by specific inhibitors significantly inhibited cell proliferation in vitro and tumor growth in vivo of lung cancer cells. Our study demontrated that the TGF-β and IL-6/JAK2/STAT3 signaling pathways form a positive feedback signaling loop that mediated the interactions between MFs and lung cancer cells. Targeted inhibiton of this signaling loop could be a new approach for lung cancer prevention and therapy.

Title: The Nuclear Effector of Wnt-Signaling, Tcf1, Functions as a T-Cell–Specific Tumor Suppressor for Development of Lymphomas Content: The HMG-box factor Tcf1 is required during T-cell development in the thymus and mediates the nuclear response to Wnt signals. Tcf1(-/-) mice have previously been characterized and show developmental blocks at the CD4-CD8- double negative (DN) to CD4+CD8+ double positive transition. Due to the blocks in T-cell development, Tcf1(-/-) mice normally have a very small thymus. Unexpectedly, a large proportion of Tcf1(-/-) mice spontaneously develop thymic lymphomas with 50% of mice developing a thymic lymphoma/leukemia at the age of 16 wk. These lymphomas are clonal, highly metastatic, and paradoxically show high Wnt signaling when crossed with Wnt reporter mice and have high expression of Wnt target genes Lef1 and Axin2. In wild-type thymocytes, Tcf1 is higher expressed than Lef1, with a predominance of Wnt inhibitory isoforms. Loss of Tcf1 as repressor of Lef1 leads to high Wnt activity and is the initiating event in lymphoma development, which is exacerbated by activating Notch1 mutations. Thus, Notch1 and loss of Tcf1 functionally act as collaborating oncogenic events. Tcf1 deficiency predisposes to the development of thymic lymphomas by ectopic up-regulation of Lef1 due to lack of Tcf1 repressive isoforms and frequently by cooperating activating mutations in Notch1. Tcf1 therefore functions as a T-cell-specific tumor suppressor gene, besides its established role as a Wnt responsive transcription factor. Thus, Tcf1 acts as a molecular switch between proliferative and repressive signals during T-lymphocyte development in the thymus.

Title: Stromal Fibroblasts Present in Invasive Human Breast Carcinomas Promote Tumor Growth and Angiogenesis through Elevated SDF-1/CXCL12 Secretion Content: Fibroblasts often constitute the majority of the stromal cells within a breast carcinoma, yet the functional contributions of these cells to tumorigenesis are poorly understood. Using a coimplantation tumor xenograft model, we demonstrate that carcinoma-associated fibroblasts (CAFs) extracted from human breast carcinomas promote the growth of admixed breast carcinoma cells significantly more than do normal mammary fibroblasts derived from the same patients. The CAFs, which exhibit the traits of myofibroblasts, play a central role in promoting the growth of tumor cells through their ability to secrete stromal cell-derived factor 1 (SDF-1); CAFs promote angiogenesis by recruiting endothelial progenitor cells (EPCs) into carcinomas, an effect mediated in part by SDF-1. CAF-secreted SDF-1 also stimulates tumor growth directly, acting through the cognate receptor, CXCR4, which is expressed by carcinoma cells. Our findings indicate that fibroblasts within invasive breast carcinomas contribute to tumor promotion in large part through the secretion of SDF-1.

Title: Interleukin-2 and inflammation induce distinct transcriptional programs that promote the differentiation of effector cytolytic T cells. Content: Interleukin(IL)-2 and inflammation regulate effector and memory cytolytic T-lymphocyte (CTL) generation during infection. We demonstrate a complex interplay between IL-2 and inflammatory signals during CTL differentiation. IL-2 stimulation induced the transcription factor eomesodermin (Eomes), upregulated perforin (Prf1) transcription, and repressed re-expression of memory CTL markers Bcl6 and IL-7Ralpha. Binding of Eomes and STAT5 to Prf1 cis-regulatory regions correlated with transcriptional initiation (increased recruitment of RNA polymerase II to the Prf1 promoter). Inflammation (CpG, IL-12) enhanced expression of IL-2Ralpha and the transcription factor T-bet, but countered late Eomes and perforin induction while preventing IL-7Ralpha repression by IL-2. After infection of mice with lymphocytic choriomeningitis virus, IL-2Ralpha-deficient effector CD8(+) T cells expressed more Bcl6 but less perforin and granzyme B, formed fewer KLRG-1(+) and T-bet-expressing CTL, and killed poorly. Thus, inflammation influences both effector and memory CTL differentiation, whereas persistent IL-2 stimulation promotes effector at the expense of memory CTL development.

Title: Blood monocytes consist of two principal subsets with distinct migratory properties Content: Peripheral blood monocytes are a heterogeneous population of circulating leukocytes. Using a murine adoptive transfer system to probe monocyte homing and differentiation in vivo, we identified two functional subsets among murine blood monocytes: a short-lived CX(3)CR1(lo)CCR2(+)Gr1(+) subset that is actively recruited to inflamed tissues and a CX(3)CR1(hi)CCR2(-)Gr1(-) subset characterized by CX(3)CR1-dependent recruitment to noninflamed tissues. Both subsets have the potential to differentiate into dendritic cells in vivo. The level of CX(3)CR1 expression also defines the two major human monocyte subsets, the CD14(+)CD16(-) and CD14(lo)CD16(+) monocytes, which share phenotype and homing potential with the mouse subsets. These findings raise the potential for novel therapeutic strategies in inflammatory diseases.

Title: BCAP links IL-1R to the PI3K–mTOR pathway and regulates pathogenic Th17 cell differentiation Content: The toll-like receptor (TLR) and interleukin (IL)-1 family of receptors share several signaling components, including the most upstream adapter, MyD88. We previously reported the discovery of B cell adapter for phosphoinositide 3-kinase (BCAP) as a novel toll-IL-1 receptor homology domain-containing adapter that regulates inflammatory responses downstream of TLR signaling. Here we find that BCAP plays a critical role downstream of both IL-1 and IL-18 receptors to regulate T helper (Th) 17 and Th1 cell differentiation, respectively. Absence of T cell intrinsic BCAP did not alter development of naturally arising Th1 and Th17 lineages but led to defects in differentiation to pathogenic Th17 lineage cells. Consequently, mice that lack BCAP in T cells had reduced susceptibility to experimental autoimmune encephalomyelitis. More importantly, we found that BCAP is critical for IL-1R-induced phosphoinositide 3-kinase-Akt-mechanistic target of rapamycin (mTOR) activation, and minimal inhibition of mTOR completely abrogated IL-1β-induced differentiation of pathogenic Th17 cells, mimicking BCAP deficiency. This study establishes BCAP as a critical link between IL-1R and the metabolic status of activated T cells that ultimately regulates the differentiation of inflammatory Th17 cells.

Title: Inhibition of receptor-mediated calcium influx in T cells by unsaturated non-esterified fatty acids. Content: The effect of omega-3, omega-6 and omega-9 unsaturated fatty acids (UFAs) on receptor-mediated Ca2+ entry was investigated in a T-cell line (JURKAT) by using anti-CD3 antibodies (OKT3) to induce intracellular Ca2+ [( Ca2+]i) increase and Ca2+ influx. All the UFAs, as well as Ni2+ ions and 12-O-tetradecanoylphorbol 13-acetate, decreased the OKT3-induced sustained [Ca2+]i increase to basal levels. Although non-esterified fatty acids activate protein kinase C (PKC) [McPhail, Clayton & Snyderman (1984) Science 224, 622-624; Murakami, Chan & Routtenberg (1986) J. Biol. Chem. 261, 15424-15429], studies using H-7 and analysis of the PKC-dependent phosphorylation of 19 and 80 kDa marker substrates ruled out the involvement of PKC in UFA-induced inhibition of Ca2+ entry. Flow-cytometry analysis showed that UFAs do not interfere with antibody-receptor binding. BSA (0.2%, w/v) reversed the effect of UFAs after these fatty acids have decreased the OKT3-induced [Ca2+]i increase to basal levels. The relevance of these findings and possible mechanisms for inhibition by UFAs of receptor-mediated Ca2+ influx were discussed.

Title: Oncostatic effects of the indole melatonin and expression of its cytosolic and nuclear receptors in cultured human melanoma cell lines. Content: Melatonin has been shown to have oncostatic effects on malignant melanoma in vitro and in vivo. We studied the growth suppressive effects of melatonin over a wide range of concentrations in four melanoma cell lines (SBCE2, WM-98, WM-164 and SKMEL-188) representative for different growth stages and phenotype. Melanoma cells were incubated with melatonin 10(-12)-10(-3) M, and proliferation and clonogenicity was assessed at 12 h and 14 days, respectively. We also determined the expression of cytosolic quinone oxidoreductases NQO1, NQO2 (known as MT3 receptor) and nuclear receptor RORalpha by RT-PCR. Melatonin at pharmacological concentrations (10(-3)-10(-7) M) suppressed proliferation in all melanoma cell lines. In SKMEL-188 cells cultured in serum-free media, melatonin at low concentrations (10(-12)-10(-10) M) also slightly attenuated the proliferation. The effects of pharmacological doses of melatonin were confirmed in the clonogenic assay. Expression of NQO1 was detected in all cell lines, whereas NQO2 and nuclear receptor RORalpha including its isoform RORalpha4 were present only in SBCE2, WM-164 and WM-98. Thus, melatonin differentially suppressed proliferation in melanoma cell lines of different behaviour. The intensity of the oncostatic response to melatonin could be related to the cell-line specific pattern of melatonin cellular receptors and cytosolic binding protein expression.

Title: Interaction of TNF with TNF receptor type 2 promotes expansion and function of mouse CD4+CD25+ T regulatory cells. Content: Although TNF is a major proinflammatory cytokine, increasing evidence indicates that TNF also has immunosuppressive feedback effects. We have demonstrated in this study that, in both resting and activated states, mouse peripheral CD4(+)CD25(+) T regulatory cells (Tregs) expressed remarkably higher surface levels of TNFR2 than CD4(+)CD25(-) T effector cells (Teffs). In cocultures of Tregs and Teffs, inhibition of proliferation of Teffs by Tregs was initially transiently abrogated by exposure to TNF, but longer exposure to TNF restored suppressive effects. Cytokine production by Teffs remained continually suppressed by Tregs. The profound anergy of Tregs in response to TCR stimulation was overcome by TNF, which expanded the Treg population. Furthermore, in synergy with IL-2, TNF expanded Tregs even more markedly up-regulated expression of CD25 and FoxP3 and phosphorylation of STAT5, and enhanced the suppressive activity of Tregs. Unlike TNF, IL-1beta and IL-6 did not up-regulate FoxP3-expressing Tregs. Furthermore, the number of Tregs increased in wild-type mice, but not in TNFR2(-/-) mice following sublethal cecal ligation and puncture. Depletion of Tregs significantly decreased mortality following cecal ligation and puncture. Thus, the stimulatory effect of TNF on Tregs resembles the reported costimulatory effects of TNF on Teffs, but is even more pronounced because of the higher expression of TNFR2 by Tregs. Moreover, our study suggests that the slower response of Tregs than Teffs to TNF results in delayed immunosuppressive feedback effects.

Title: MicroRNA-21 is up-regulated in allergic airway inflammation and regulates IL-12p35 expression. Content: Allergic airway inflammation is characterized by marked in situ changes in gene and protein expression, yet the role of microRNAs (miRNAs), a new family of key mRNA regulatory molecules, in this process has not yet been reported. Using a highly sensitive microarray-based approach, we identified 21 miRNAs with differential expression between doxycycline-induced lung-specific IL-13 transgenic mice (with allergic airway inflammation) and control mice. In particular, we observed overexpression of miR-21 and underexpression of miR-1 in the induced IL-13 transgenic mice compared with control mice. These findings were validated in two independent models of allergen-induced allergic airway inflammation and in IL-4 lung transgenic mice. Although IL-13-induced miR-21 expression was IL-13Ralpha1 dependent, allergen-induced miR-21 expression was mediated mainly independent of IL-13Ralpha1 and STAT6. Notably, predictive algorithms identified potential direct miR-21 targets among IL-13-regulated lung transcripts, such as IL-12p35 mRNA, which was decreased in IL-13 transgenic mice. Introduction of pre-miR-21 dose dependently inhibited cellular expression of a reporter vector harboring the 3'-untranslated region of IL-12p35. Moreover, mutating miR-21 binding sites in IL-12p35 3'-untranslated region abrogated miR-21-mediated repression. In summary, we have identified a miRNA signature in allergic airway inflammation, which includes miR-21 that modulates IL-12, a molecule germane to Th cell polarization.

Title: The human long non-coding RNA-RoR is a p53 repressor in response to DNA damage Content: It is well known that upon stress, the level of the tumor suppressor p53 is remarkably elevated. However, despite extensive studies, the underlying mechanism involving important inter-players for stress-induced p53 regulation is still not fully understood. We present evidence that the human lincRNA-RoR (RoR) is a strong negative regulator of p53. Unlike MDM2 that causes p53 degradation through the ubiquitin-proteasome pathway, RoR suppresses p53 translation through direct interaction with the heterogeneous nuclear ribonucleoprotein I (hnRNP I). Importantly, a 28-base RoR sequence carrying hnRNP I binding motifs is essential and sufficient for p53 repression. We further show that RoR inhibits p53-mediated cell cycle arrest and apoptosis. Finally, we demonstrate a RoR-p53 autoregulatory feedback loop where p53 transcriptionally induces RoR expression. Together, these results suggest that the RoR-hnRNP I-p53 axis may constitute an additional surveillance network for the cell to better respond to various stresses.

Title: Chemosensitization of acute myeloid leukemia (AML) following mobilization by the CXCR4 antagonist AMD3100. Content: The CXCR4-SDF-1 axis plays a central role in the trafficking and retention of normal and malignant stem cells in the bone marrow (BM) microenvironment. Here, we used a mouse model of acute promyelocytic leukemia (APL) and a small molecule competitive antagonist of CXCR4, AMD3100, to examine the interaction of mouse APL cells with the BM microenvironment. APL cells from a murine cathepsin G-PML-RARalpha knockin mouse were genetically modified with firefly luciferase (APL(luc)) to allow tracking by bioluminescence imaging. Coculture of APL(luc) cells with M2-10B4 stromal cells protected the leukemia cells from chemotherapy-induced apoptosis in vitro. Upon injection into syngeneic recipients, APL(luc) cells rapidly migrated to the BM followed by egress to the spleen then to the peripheral blood with death due to leukostasis by day 15. Administration of AMD3100 to leukemic mice induced a 1.6-fold increase in total leukocytes and a 9-fold increase of circulating APL blast counts, which peak at 3 hours and return to baseline by 12 hours. Treatment of leukemic mice with chemotherapy plus AMD3100 resulted in decreased tumor burden and improved overall survival compared with mice treated with chemotherapy alone. These studies provide a proof-of-principle for directing therapy to the critical tethers that promote AML-niche interactions.

Title: MicroRNA-203 inhibits cellular proliferation and invasion by targeting Bmi1 in non-small cell lung cancer. Content: MicroRNAs are proposed to serve vital functions in the regulation of tumor progression and invasion. However, the expression levels of miR-203 in non-small cell lung cancer (NSCLC) and its clinical significance remain unknown. In the present study, the association between B-cell-specific moloney murine leukemia virus insertion site 1 (Bmi1) and miR-203 was investigated. miR-203 was demonstrated to act as a tumor suppressor by regulating the expression of Bmi1. miR-203 expression levels were downregulated in NSCLC tissues while Bmi1 expression was upregulated in NSCLC tissues and cell lines. Furthermore, downregulated Bmi1 or enhanced miR-203 expression inhibited NSCLC cell proliferation and invasion in vitro. In addition, a dual-luciferase reporter assay was performed, which identified Bmi1 as a novel target of miR-203. In conclusion, the present study demonstrated that miR-203 functions as a tumor suppressor and is important in inhibiting the proliferation of NSCLC cells through targeting Bmi1. These findings indicate that miR-203 may be useful as a novel potential therapeutic target for NSCLC.

Title: VEGF inhibits tumor cell invasion and mesenchymal transition through a MET/VEGFR2 complex. Content: Inhibition of VEGF signaling leads to a proinvasive phenotype in mouse models of glioblastoma multiforme (GBM) and in a subset of GBM patients treated with bevacizumab. Here, we demonstrate that vascular endothelial growth factor (VEGF) directly and negatively regulates tumor cell invasion through enhanced recruitment of the protein tyrosine phosphatase 1B (PTP1B) to a MET/VEGFR2 heterocomplex, thereby suppressing HGF-dependent MET phosphorylation and tumor cell migration. Consequently, VEGF blockade restores and increases MET activity in GBM cells in a hypoxia-independent manner, while inducing a program reminiscent of epithelial-to-mesenchymal transition highlighted by a T-cadherin to N-cadherin switch and enhanced mesenchymal features. Inhibition of MET in GBM mouse models blocks mesenchymal transition and invasion provoked by VEGF ablation, resulting in substantial survival benefit.

Title: Feedback upregulation of HER3 (ErbB3) expression and activity attenuates antitumor effect of PI3K inhibitors. Content: We examined the effects of an inhibitor of PI3K, XL147, against human breast cancer cell lines with constitutive PI3K activation. Treatment with XL147 resulted in dose-dependent inhibition of cell growth and levels of pAKT and pS6, signal transducers in the PI3K/AKT/TOR pathway. In HER2-overexpressing cells, inhibition of PI3K was followed by up-regulation of expression and phosphorylation of multiple receptor tyrosine kinases, including HER3. Knockdown of FoxO1 and FoxO3a transcription factors suppressed the induction of HER3, InsR, IGF1R, and FGFR2 mRNAs upon inhibition of PI3K. In HER2(+) cells, knockdown of HER3 with siRNA or cotreatment with the HER2 inhibitors trastuzumab or lapatinib enhanced XL147-induced cell death and inhibition of pAKT and pS6. Trastuzumab and lapatinib each synergized with XL147 for inhibition of pAKT and growth of established BT474 xenografts. These data suggest that PI3K antagonists will inhibit AKT and relieve suppression of receptor tyrosine kinase expression and their activity. Relief of this feedback limits the sustained inhibition of the PI3K/AKT pathway and attenuates the response to these agents. As a result, PI3K pathway inhibitors may have limited clinical activity overall if used as single agents. In patients with HER2-overexpressing breast cancer, PI3K inhibitors should be used in combination with HER2/HER3 antagonists.

Title: SOD1 Integrates Signals from Oxygen and Glucose to Repress Respiration Content: Cu/Zn superoxide dismutase (SOD1) is an abundant enzyme that has been best studied as a regulator of antioxidant defense. Using the yeast Saccharomyces cerevisiae, we report that SOD1 transmits signals from oxygen and glucose to repress respiration. The mechanism involves SOD1-mediated stabilization of two casein kinase 1-gamma (CK1γ) homologs, Yck1p and Yck2p, required for respiratory repression. SOD1 binds a C-terminal degron we identified in Yck1p/Yck2p and promotes kinase stability by catalyzing superoxide conversion to peroxide. The effects of SOD1 on CK1γ stability are also observed with mammalian SOD1 and CK1γ and in a human cell line. Therefore, in a single circuit, oxygen, glucose, and reactive oxygen can repress respiration through SOD1/CK1γ signaling. Our data therefore may provide mechanistic insight into how rapidly proliferating cells and many cancers accomplish glucose-mediated repression of respiration in favor of aerobic glycolysis.

Title: Aire deficiency promotes TRP-1-specific immune rejection of melanoma. Content: The thymic transcription factor autoimmune regulator (Aire) prevents autoimmunity in part by promoting expression of tissue-specific self-antigens, which include many cancer antigens. For example, AIRE-deficient patients are predisposed to vitiligo, an autoimmune disease of melanocytes that is often triggered by efficacious immunotherapies against melanoma. Therefore, we hypothesized that Aire deficiency in mice may elevate immune responses to cancer and provide insights into how such responses might be triggered. In this study, we show that Aire deficiency decreases thymic expression of TRP-1 (TYRP1), which is a self-antigen in melanocytes and a cancer antigen in melanomas. Aire deficiency resulted in defective negative selection of TRP-1-specific T cells without affecting thymic numbers of regulatory T cells. Aire-deficient mice displayed elevated T-cell immune responses that were associated with suppression of melanoma outgrowth. Furthermore, transplantation of Aire-deficient thymic stroma was sufficient to confer more effective immune rejection of melanoma in an otherwise Aire wild-type host. Together, our work showed how Aire deficiency can enhance immune responses against melanoma and how manipulating TRP-1-specific T-cell negative selection may offer a logical strategy to enhance immune rejection of melanoma.

Title: Naringenin inhibits allergen-induced airway inflammation and airway responsiveness and inhibits NF-kappaB activity in a murine model of asthma. Content: Naringenin, a flavonoid, has antiinflammatory and immunomodulatory properties. We investigated whether naringenin could attenuate allergen-induced airway inflammation and its possible mechanism in a murine model of asthma. Mice were sensitized and challenged with ovalbumin. Some mice were administered with naringenin before ovalbumin challenge. We evaluated the development of airway inflammation and airway reactivity. Interleukin (IL)4, IL13, chemokine (C-C motif) ligand (CCL)5, and CCL11 in bronchoalveolar lavage fluid and serum total IgE were detected by ELISA. IkappaBalpha degradation and inducible nitric oxide synthase (iNOS) in lungs were measured by Western blot. We also tested NF-kappaB binding activity by electrophoretic mobility shift assay. The mRNA levels of iNOS, CCL5, and CCL11 were detected by real-time PCR. Naringenin attenuated ovalbumin-induced airway inflammation and airway reactivity in experimental mice. The naringenin-treated mice had lower levels of IL4 and IL13 in the bronchoalveolar lavage fluid and lower serum total IgE. Furthermore, naringenin inhibited pulmonary IkappaBalpha degradation and NF-kappaB DNA-binding activity. The levels of CCL5, CCL11, and iNOS were also significantly reduced. The results indicated that naringenin may play protective roles in the asthma process. The inhibition of NF-kappaB and the decreased expression of its target genes may account for this phenomenon.

Title: The long non-coding RNA H19-derived miR-675 modulates human gastric cancer cell proliferation by targeting tumor suppressor RUNX1. Content: The lncRNA H19 has been recently shown to be upregulated and play important roles in gastric cancer tumorigenesis. However, the precise molecular mechanism of H19 and its mature product miR-675 in the carcinogenesis of gastric cancer remains unclear. In this study, we found that miR-675 was positively expressed with H19 and was a pivotal mediator in H19-induced gastric cancer cell growth promotion. Subsequently, the tumor suppressor Runt Domain Transcription Factor1 (RUNX1) was confirmed to be a direct target of miR-675 using a luciferase reporter assay and Western blotting analyses. A series of rescue assays indicated that RUNX1 mediated H19/miR-67-induced gastric cancer cell phenotypic changes. Moreover, the inverse relationship between the expression of RUNX1 and H19/miR-675 was also revealed in gastric cancer tissues and gastric cancer cell lines. Taken together, our study demonstrated that the novel pathway H19/miR-675/RUNX1 regulates gastric cancer development and may serve as a potential target for gastric cancer therapy.

Title: Suppressor of cytokine signaling 3 inhibits antiviral IFN-beta signaling to enhance HIV-1 replication in macrophages. Content: HIV-1 replication within macrophages of the CNS often results in cognitive and motor impairment, which is known as HIV-associated dementia (HAD) in its most severe form. IFN-beta suppresses viral replication within these cells during early CNS infection, but the effect is transient. HIV-1 eventually overcomes this protective innate immune response to resume replication through an unknown mechanism, initiating the progression toward HAD. In this article, we show that Suppressor of Cytokine Signaling (SOCS)3, a molecular inhibitor of IFN signaling, may allow HIV-1 to evade innate immunity within the CNS. We found that SOCS3 is elevated in an in vivo SIV/macaque model of HAD and that the pattern of expression correlates with recurrence of viral replication and onset of CNS disease. In vitro, the HIV-1 regulatory protein transactivator of transcription induces SOCS3 in human and murine macrophages in a NF-kappaB-dependent manner. SOCS3 expression attenuates the response of macrophages to IFN-beta at proximal levels of pathway activation and downstream antiviral gene expression and consequently overcomes the inhibitory effect of IFN-beta on HIV-1 replication. These studies indicate that SOCS3 expression, induced by stimuli present in the HIV-1-infected brain, such as transactivator of transcription, inhibits antiviral IFN-beta signaling to enhance HIV-1 replication in macrophages. This consequence of SOCS3 expression in vitro, supported by a correlation with increased viral load and onset of CNS disease in vivo, suggests that SOCS3 may allow HIV-1 to evade the protective innate immune response within the CNS, allowing the recurrence of viral replication and, ultimately, promoting progression toward HAD.

Title: Arachidonic acid cytochrome P450 epoxygenase pathway. Content: Cytochrome P450 (CYP) epoxygenases convert arachidonic acid to four epoxyeicosatrienoic acid (EET) regioisomers, 5,6-, 8,9-, 11,12-, and 14,15-EET, that function as autacrine and paracrine mediators. EETs produce vascular relaxation by activating smooth muscle large-conductance Ca2+-activated K+ channels (BKCa). In addition, they have anti-inflammatory effects on blood vessels and in the kidney, promote angiogenesis, and protect ischemic myocardium and brain. CYP epoxygenases also convert eicosapentaenoic acid to vasoactive epoxy-derivatives, and endocannabinoids containing 11,12- and 14,15-EET are formed. Many EET actions appear to be initiated by EET binding to a membrane receptor that activates ion channels and intracellular signal transduction pathways. However, EETs also are taken up by cells, are incorporated into phospholipids, and bind to cytosolic proteins and nuclear receptors, suggesting that some functions may occur through direct interaction of the EET with intracellular effector systems. Soluble epoxide hydrolase (sEH) converts EETs to dihydroxyeicosatrienoic acids (DHETs). Because this attenuates many of the functional effects of EETs, sEH inhibition is being evaluated as a mechanism for increasing and prolonging the beneficial actions of EETs.

Title: Inflammatory T cells rapidly induce differentiation of human bone marrow stromal cells into mature osteoblasts. Content: Activated T cells secrete multiple osteoclastogenic cytokines which play a major role in the bone destruction associated with rheumatoid arthritis. While the role of T cells in osteoclastogenesis has received much attention recently, the effect of T cells on osteoblast formation and activity is poorly defined. In this study, we investigated the hypothesis that in chronic inflammation activated T cells contribute to enhanced bone turnover by promoting osteoblastic differentiation. We show that T cells produce soluble factors that induce alkaline phosphatase activity in bone marrow stromal cells and elevated expression of mRNA for Runx2 and osteocalcin. This data indicate that T cell derived factors have the capacity to stimulate the differentiation of bone marrow stromal cells into the osteoblast phenotype. RANKL mRNA was undetectable under any conditions in highly purified bone marrow stromal cells. In contrast, RANKL was constitutively expressed in primary osteoblasts and only moderately up-regulated by activated T cell conditioned medium. Interestingly, both bone marrow stromal cells and osteoblasts expressed mRNA for RANK, which was strongly up-regulated in both cell types by activated T cell conditioned medium. Although, mRNA for the RANKL decoy receptor, osteoprotegerin, was also up-regulated by activated T cell conditioned medium, it's inhibitory effects may be mitigated by a simultaneous rise in the osteoprotegerin competitor TNF-related apoptosis-inducing ligand. Based on our data we propose that during chronic inflammation, T cells regulate bone loss by a dual mechanism involving both direct stimulation of osteoclastogenesis, by production of osteoclastogenic cytokines, and indirectly by induction of osteoblast differentiation and up-regulation of bone turnover via coupling.

Title: High-mobility group box-1 protein induces osteogenic phenotype changes in aortic valve interstitial cells. Content: OBJECTIVES Calcific aortic valve (AV) disease is known to be an inflammation-related process. High-mobility group box-1 (HMGB1) protein and Toll-like receptor 4 (TLR4) have been reported to participate in several inflammatory diseases. The purpose of the present study was to determine whether the HMGB1-TLR4 axis is involved in calcific AV disease, and to evaluate the effect of HMGB1, and its potential mechanisms, on the pro-osteogenic phenotype change of valvular interstitial cells (VICs). METHODS Expression of HMGB1 and TLR4 in human calcific AVs was evaluated using immunohistochemical staining and immunoblotting. Cultured VICs were used as an in vitro model. The VICs were stimulated with HMGB1 for analysis, with versus without TLR4 small interfering ribonucleic acid (siRNA), c-Jun N-terminal kinase mitogen-activated protein kinase (JNK MAPK), and nuclear factor kappa-B (NF-κB) inhibitors. RESULTS Enhanced accumulation of HMGB1 and TLR4 was observed in calcific valves. Moreover, we found that HMGB1 induced high levels of pro-inflammatory cytokine production and promoted the osteoblastic differentiation and calcification of VICs. In addition, HMGB1 induced phosphorylation of JNK MAPK and NF-κB. However, these effects were markedly suppressed by siRNA silencing of TLR4. In addition, blockade of JNK MAPK and NF-κB phosphorylation prohibited HMGB1-induced production of pro-osteogenic factors, and mineralization of VICs. CONCLUSIONS The HMGB1 protein may promote osteoblastic differentiation and calcification of VICs, through the TLR4-JNK-NF-κB signaling pathway.

Title: Sirtuin-1 is a nutrient-dependent modulator of inflammation Content: Inflammation accompanies obesity and its comorbidities-type 2 diabetes, non-alcoholic fatty liver disease and atherosclerosis, among others-and may contribute to their pathogenesis. Yet the cellular machinery that links nutrient sensing to inflammation remains incompletely characterized. The protein deacetylase sirtuin-1 (SirT1) is activated by energy depletion and plays a critical role in the mammalian response to fasting. More recently it has been implicated in the repression of inflammation. SirT1 mRNA and protein expression are suppressed in obese rodent and human white adipose tissue, while experimental reduction of SirT1 in adipocytes and macrophages causes low-grade inflammation that mimics that observed in obesity. Thus suppression of SirT1 during overnutrition may be critical to the development of obesity-associated inflammation. This effect is attributable to multiple actions of SirT1, including direct deacetylation of NFκB and chromatin remodeling at inflammatory gene promoters. In this work, we report that SirT1 is also suppressed by diet-induced obesity in macrophages, which are key contributors to the ontogeny of metabolic inflammation. Thus, SirT1 may be a common mechanism by which cells sense nutrient status and modulate inflammatory signaling networks in accordance with organismal energy availability.