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1.  Identification of beryllium-dependent peptides recognized by CD4+ T cells in chronic beryllium disease 
The Journal of Experimental Medicine  2013;210(7):1403-1418.
Identification of peptides that form complexes with beryllium and class II HLA molecules and are recognized by CD4+ T cells from patients with chronic beryllium disease.
Chronic beryllium disease (CBD) is a granulomatous disorder characterized by an influx of beryllium (Be)-specific CD4+ T cells into the lung. The vast majority of these T cells recognize Be in an HLA-DP–restricted manner, and peptide is required for T cell recognition. However, the peptides that stimulate Be-specific T cells are unknown. Using positional scanning libraries and fibroblasts expressing HLA-DP2, the most prevalent HLA-DP molecule linked to disease, we identified mimotopes and endogenous self-peptides that bind to MHCII and Be, forming a complex recognized by pathogenic CD4+ T cells in CBD. These peptides possess aspartic and glutamic acid residues at p4 and p7, respectively, that surround the putative Be-binding site and cooperate with HLA-DP2 in Be coordination. Endogenous plexin A peptides and proteins, which share the core motif and are expressed in lung, also stimulate these TCRs. Be-loaded HLA-DP2–mimotope and HLA-DP2–plexin A4 tetramers detected high frequencies of CD4+ T cells specific for these ligands in all HLA-DP2+ CBD patients tested. Thus, our findings identify the first ligand for a CD4+ T cell involved in metal-induced hypersensitivity and suggest a unique role of these peptides in metal ion coordination and the generation of a common antigen specificity in CBD.
PMCID: PMC3698527  PMID: 23797096
3.  Beryllium-Specific CD4+ T Cells in Blood as a Biomarker of Disease Progression 
CD4+ T cells are responsible for the progressive lung damage seen in patients with chronic beryllium disease (CBD), a granulomatous lung disorder in which antigen-specific, Th1-type cytokine-secreting T cells have been characterized. Compared to beryllium (Be)-sensitized subjects, an increased number of Be-responsive T cells are present in the blood of CBD patients.
The aim of this study was to determine whether the number of Be-specific T cells in blood predicted the development of CBD in a cohort of Be-exposed subjects.
Using IFN-γ ELISPOT and proliferation-based assays, we determined the frequency and proliferative capacity of Be-responsive T cells in blood.
Compared with the Be lymphocyte proliferation test which detected an abnormal Be-induced proliferative response in 11 of 260 (4.2%) workers from a Be-machining facility, IFN-γ ELISPOT detected a sensitization rate of 10% (χ2 = 55.7; P < 0.0001). A significant positive correlation was also noted between the number of Be-responsive CD4+ T cells in blood and lung of CBD patients. Importantly, the transition from Be sensitization to CBD was associated with an increased number of antigen-specific T cells in blood.
These findings have important implications for Be-induced disease and potentially other immune-mediated disorders, suggesting that the frequency of antigen-specific T cells in blood can serve as a noninvasive biomarker to predict disease development and severity of the Be-specific CD4+ T cell alveolitis.
Clinical implications
These findings suggest that the number of Be-responsive T cells in the circulation can serve as a biomarker of disease progression and as an estimate of the severity of Be-induced lung inflammation.
PMCID: PMC3205205  PMID: 21943943
Human; Lung; CD4-Positive T-Lymphocytes; Beryllium; Cytokines; Granuloma; ELISPOT
4.  Mutagenesis of beryllium-specific T cell receptors suggests an unusual binding topology for antigen recognition1 
Unconventional antigens, such as metals, stimulate T cells in a very specific manner. To delineate the binding landscape for metal-specific T cell recognition, alanine screens were performed on a set of beryllium (Be)-specific T cell receptors (TCR) derived from the lung of a chronic beryllium disease patient. These TCRs are HLA-DP2-restricted and express nearly identical TCR Vβ5.1 chains coupled with different TCR α-chains. Site-specific mutagenesis of all amino acids comprising the complementarity determining regions of the TCRA and TCRB genes showed a dominant role for Vβ5.1 residues in Be recognition, with little contribution from the TCR α-chain. Solvent-exposed residues along the α-helices of the HLA-DP2 α- and β-chains were also mutated to alanine. Two β-chain residues, located near the proposed Be binding site of HLA-DP2, played a dominant role in T cell recognition with no contribution from the HLA-DP2 α-chain. These findings suggest that Be-specific T cells recognize antigen using an unconventional binding topology, with the majority of interactions contributed by TCR Vβ5.1 residues and the HLA-DP2 β1-chain. Thus, unusual docking topologies are not exclusively used by autoreactive T cells, but also for the recognition of unconventional metal antigens, such as Be.
PMCID: PMC3178675  PMID: 21873524
Human; T cells; MHC; Lung; T cell receptors
5.  Altered Immune Phenotype in Peripheral Blood Cells of Patients with Scleroderma-Associated Pulmonary Hypertension 
Pulmonary arterial hypertension is a common and fatal complication of scleroderma that may involve inflammatory and autoimmune mechanisms. Alterations in the gene expression of peripheral blood mononuclear cells have been previously described in patients with pulmonary arterial hypertension. Our goal is to identify differentially expressed genes in peripheral blood mononuclear cells in scleroderma patients with and without pulmonary hypertension as biomarkers of disease.
Gene expression analysis was performed on a Microarray Cohort of scleroderma patients with (n=10) and without (n=10) pulmonary hypertension. Differentially expressed genes were confirmed in the Microarray Cohort and validated in a Validation Cohort of scleroderma patients with (n=15) and without (n=19) pulmonary hypertension by RT-qPCR. We identified inflammatory and immune-related genes including interleukin-7 receptor (IL-7R) and chemokine receptor 7 as differentially expressed in patients with scleroderma-associated pulmonary hypertension. Flow cytometry confirmed decreased expression of IL-7R on circulating CD4+ T-cells from scleroderma patients with pulmonary hypertension.
Differences exist in the expression of inflammatory and immune-related genes in peripheral blood cells from patients with scleroderma-related pulmonary hypertension compared to those with normal pulmonary artery pressures. These findings may have implications as biomarkers to screen at-risk populations for early diagnosis and provide insight into mechanisms of scleroderma-related pulmonary hypertension.
PMCID: PMC2966033  PMID: 20973920
Pulmonary Hypertension; Gene Array; Gene Expression; Interleukins; Inflammation
6.  Deficient and Dysfunctional Regulatory T Cells in the Lungs of Chronic Beryllium Disease Subjects 
Rationale: Chronic beryllium disease (CBD) is a CD4+ T cell–mediated disorder characterized by persistent lung inflammation. Naturally occurring regulatory T (Treg) cells modulate adaptive immune responses. The role of this T-cell subset in beryllium-induced lung disease is unknown.
Objectives: The aim of this study was to determine whether dysfunctional Treg cells in the lung contribute to the “unchecked” inflammatory response that characterizes CBD.
Methods: Using blood and bronchoalveolar lavage (BAL) cells from normal control subjects and individuals with beryllium-induced disease, we determined the frequency and function of naturally occurring Treg cells.
Measurements and Main Results: A significantly decreased percentage and expression of FoxP3 in BAL CD4+ T cells from CBD patients compared with beryllium-sensitized subjects was seen, and the percentage of FoxP3-expressing CD4+ Treg cells in BAL inversely correlated with disease severity. In contrast to blood Treg cells derived from beryllium-sensitized subjects and patients with CBD that completely suppressed blood responder T-cell proliferation, BAL FoxP3-expressing Treg cells from patients with CBD are unable to suppress anti–CD3-mediated BAL T-cell proliferation. Mixing studies showed that blood Treg cells are capable of suppressing autologous BAL responder T cells. Conversely, BAL CD4+ Treg cells are incapable of suppressing blood T cells, confirming that the failure of BAL Treg cells to suppress T-cell proliferation is caused by a dysfunctional Treg cell subset and not by resistance of BAL effector T cells to suppression.
Conclusions: These findings suggest that the deficient and dysfunctional Treg cells in the lung of patients with CBD contribute to the persistent inflammatory response in this disease.
PMCID: PMC2891494  PMID: 20299529
fibrosis; human; granuloma; inflammation
7.  CD27 Expression on CD4+ T Cells Differentiates Effector from Regulatory T Cell Subsets in the Lung1 
Beryllium exposure in the workplace can result in chronic beryllium disease, a granulomatous lung disorder characterized by CD4+ T cell alveolitis and progressive lung fibrosis. A large number of the CD4+ T cells recruited to the lung in chronic beryllium disease recognize beryllium in an Ag-specific manner and express Th1-type cytokines following T cell activation. Beryllium-responsive CD4+ T cells in the bronchoalveolar lavage (BAL) express an effector memory T cell phenotype and recognize beryllium in a CD28-independent manner. In this study, we show that the majority of beryllium-responsive CD4+ T cells in BAL have lost CD27 expression, whereas a subset of beryllium-responsive cells in blood retains expression of this costimulatory molecule. In addition, loss of CD27 on BAL CD4+ T cells inversely correlates with markers of lung inflammation. A small population of BAL CD4+ T cells retains CD27 expression, and these CD4+CD27+ T cells contain the FoxP3-expressing, naturally occurring regulatory T (Treg) cell subset. Coexpression of CD27 and CD25 identifies the majority of FoxP3-expressing Treg cells in blood and BAL, and these cells express potent suppressor function. Taken together, these findings suggest that CD27 is differentially expressed between effector T cells from the inflamed lung and can be used in conjunction with CD25 to isolate Treg cells and assess their functional capacity in an ongoing adaptive immune response in a target organ.
PMCID: PMC3061566  PMID: 19454729
8.  4-1BB Enhances Proliferation of Beryllium-Specific T Cells in the Lung of Subjects with Chronic Beryllium Disease1 
In contrast to naive T cells, reactivation of memory cells is less dependent on CD28-mediated costimulation. We have shown that circulating beryllium-specific CD4+ T cells from chronic beryllium disease patients remain CD28-dependent, while those present in the lung no longer require CD28 for T cell activation. In the present study, we analyzed whether other costimulatory molecules are essential for beryllium-induced T cell function in the lung. Enhanced proliferation of a beryllium-responsive, HLA-DP2-restricted T cell line was seen after the induction of 4-1BB ligand expression on the surface of HLA-DP2-expressing fibroblasts. Following beryllium exposure, CD4+ T cells from blood and bronchoalveolar lavage of chronic beryllium disease patients up-regulate 4-1BB expression, and the majority of beryllium-responsive, IFN-γ-producing CD4+ T cells in blood coexpress CD28 and 4-1BB. Conversely, a significant fraction of IFN-γ-producing bronchoalveolar lavage (BAL) T cells express 4-1BB in the absence of CD28. In contrast to blood, inhibition of the 4-1BB ligand-4-1BB interaction partially blocked beryllium-induced proliferation of BAL CD4+ T cells, and a lack of 4-1BB expression on BAL T cells was associated with increased beryllium-induced cell death. Taken together, these findings suggest an important role of 4-1BB in the costimulation of beryllium-responsive CD4+ T cells in the target organ.
PMCID: PMC3057106  PMID: 18768897
9.  Immunomodulatory strategies prevent the development of autoimmune emphysema 
Respiratory Research  2010;11(1):179.
PMCID: PMC3009635  PMID: 21162738
11.  Paclitaxel Arrests Growth of Intracellular Toxoplasma gondii 
Addition of paclitaxel (Taxol) at a concentration of 1 μM to Toxoplasma gondii-infected human foreskin fibroblasts arrested parasite multiplication. Division of the T. gondii tachyzoite nucleus was inhibited, leading to syncytium-like parasite structures within the fibroblasts by 24 h after infection and treatment of the cultures. By 4 days after infection and treatment of the cultures with paclitaxel, this inhibition was irreversible, since the arrested intracellular form was incapable of leaving the host cell, infecting new cells, and initiating the growth of tachyzoites with normal morphology. Specifically, when paclitaxel was added to infected cells for 4 days and then removed by washing and the infected, paclitaxel-treated cells were cultured for 4 more days, there were no remaining T. gondii organisms with normal morphology. Syncytium-like structures in the cultures that were infected and treated with paclitaxel for 8 days were similar in appearance to those in preparations of infected paclitaxel-treated fibroblasts that had been cultured for 24 to 48 h. Pretreatment of the tachyzoites for 1 h with paclitaxel followed by the removal of the paclitaxel by repeatedly centrifuging and resuspending the parasites in fresh medium without paclitaxel and then adding fresh medium prior to culture of the parasites with fibroblasts did not prevent their invasion of fibroblasts but did affect their subsequent ability to replicate within fibroblasts. Pretreatment of the fibroblasts with paclitaxel also diminished subsequent replication of T. gondii in such host cells after 8 days. Thus, paclitaxel alters the ability of T. gondii to replicate in host cells. Inhibition of parasite microtubules by such compounds at concentrations which do not interfere with the function of host cell microtubules may be useful for development of novel medicines to treat T. gondii infections in the future.
PMCID: PMC105729  PMID: 9687403

Results 1-11 (11)