although proinflammatory effects of acute hyperglycemia in inflammatory conditions and septic patients have been extensively investigated in clinical as well as experimental settings , there are still controversies about its relevance and mechanisms [ 1 , 2 ] .
. found no beneficial effect of treating acute hyperglycemia in the clinical setting of sepsis .
however , in this context it was difficult to dissect between effects directly attributable to insulin or thereby induced hypoglycemia .
similarly , hyperglycemia - related proinflammatory effects should be separated into those directly evoked by glucose and those induced by secondary hyperglycemia ( stress , inflammation ) . in case of acute hyperglycemia caused by critical illness , altered secretion of counterregulatory hormones and excessive release of proinflammatory cytokines
is observed as well as suppression of the innate immune system [ 4 , 5 ] .
these consequences of impaired leukocyte function are in part comparable to the pathophysiology observed in patients with diabetes mellitus . despite tremendous research on proinflammatory conditions related to hyperglycemia direct effects of glucose on leukocyte recruitment during inflammation
leukocyte recruitment into inflamed tissue follows a well - defined cascade of events beginning with the capture of free flowing leukocytes to the vessel wall followed by leukocyte rolling along and adhesion to the inflamed endothelial layer [ 9 , 10 ] . during rolling ,
leukocytes get into intimate contact with the endothelial surface , which allows endothelial bound chemokines ( i.e. , cxcl1 ) to interact with their specific chemokine receptors ( i.e. , cxcr2 as the main chemokine receptor on neutrophil leukocytes ) on the leukocyte surface .
this triggers the activation of 2-integrins ( i.e. , lfa1 and mac1 ) which leads to firm leukocyte arrest on the endothelium .
in addition , integrin - dependent signaling events induce cytoskeletal rearrangements and cell polarization , modifications necessary in helping to prepare the attached leukocyte to spread and crawl in search for its wayout of the vasculature into tissue [ 1013 ] . after crawling along the vessel wall
little is known about how glucose might interfere with the cascade of leukocyte recruitment in vivo .
insulin secretion promotes neutrophil chemotaxis under physiological conditions ; acute hyperglycemia leads to insulin resistance in and reduced respiratory burst of neutrophil leukocytes .
insulin resistance is seen in different tissues including muscle cells and the substrate producing organ liver .
hepatic insulin resistance leads to an exaggerated release and an increased blood concentration of not only glucose , but also of amino acids and of free fatty acids .
paradoxically , for example , fatty acids are metabolized to a smaller extent in patients with critical illness , leading to a progressively increasing vicious circle of not extractable circulating metabolic substrates . although experimental design ( route and doses of glucose , observed tissue ) varied between existing studies , they revealed increased rolling , adhesion and transmigration of leukocytes after glucose application , an effect which was at least in part reversible after insulin injection . since changes of osmolarity were repeatedly discussed to be causative of alteration of leukocyte recruitment , azcutia et al
. carried out experiments not only with the biological active d - glucose ( that is referred to as  glucose  in all existing experimental settings as well as in our investigations ) , but also with its synthetically existing enantiomer l - glucose .
osmotic changes were not causative in this setting , as l - glucose failed to alter leukocyte recruitment
. since there are no intravital microscopic studies investigating the immediate effects of glucose on leukocyte recruitment in vivo , we aimed to observe leukocyte recruitment in response to intravenous glucose application in different inflammatory mouse models by intravital microscopy . based on our experimental results we found that in contrast to tnf stimulation leukocyte adhesion and transmigration can be additionally stimulated by glucose , which seems to be dependent on cxcl1-triggered interaction of icam1 and lfa1 during trauma - induced inflammation .
icam1 mice were generated as described earlier and backcrossed for at least seven generations into the c57bl/6 background .
lfa1 and c57bl/6 wildtype ( wt ) mice were provided by charles river ( sulzfeld , germany ) .
all mice were maintained as breeding colonies at the central animal facility of the university of heidelberg , germany .
the animal experiments were approved by the animal care and use committee of the regierungsprsidium karlsruhe , germany . in certain experiments , recombinant murine tnf
( r&d systems , minneapolis , usa ) was injected intrascrotally at a dose of 500  ng per mouse 3 hours before intravital microscopy . in some experiments , recombinant murine chemokine cxcl1 ( keratinocyte - derived chemokine kc ; peprotech , london , uk ) was injected systemically at a dose of 600  ng per mouse . blocking antibodies against murine mac1 ( tib128
, clone m1/70 , rat igg2b ) and murine lfa1 ( tib217 , clone m17/4 , rat igg2a ) were obtained from american type culture collection ( atcc , manasses , usa ) and systemically administered with a dose of 100  g per mouse .
bordetella pertussis ptx was purchased from sigma - aldrich ( taufkirchen , germany ) and administered in certain experiments at a dose of 4  g per mouse 3  h prior to preparation in the trauma model .
mice were prepared for intravital microscopy as reported recently . briefly , after intraperitoneal ( i.p . )
injection of ketamine ( 125  mg / kg body weight , ketalar ; parke - davis , morris plains , usa ) and xylazine ( 12.5  mg / kg body weight ; phoenix scientific , inc .
joseph , usa ) mice were placed on a heating pad to maintain body temperature .
intravital microscopy was conducted on an upright microscope ( leica ; wetzlar , germany ) with a saline immersion objective ( sw40/0.75 numerical aperture , zeiss , jena , germany ) .
mice were intubated , and the left carotid artery was cannulated for blood sampling and the right jugular vein for glucose and systemic mab administration .
d - glucose ( 200  mg / ml ) was administered in doses of 0,25  g , 0,5  g , and 1  g / kg body weight .
the injection of the equivalent volume of normal saline ( nacl 0,9% ) served as control agent .
additional osmotic controls were performed with the biologically inactive l - glucose , purchased from sigma - aldrich ( taufkirchen , germany ) .
 refers to d - glucose that was used in all other experiments that were carried out .
blood glucose measurements were carried out throughout the experiment using accuchek ( roche diagnostics , mannheim , germany ) and additionally verified by comparing the results in sodium fluoride samples in the central laboratory of the university hospital heidelberg ( analysezentrum , heidelberg , germany ) .
after longitudinal incision and spreading of the muscle over a cover glass , the epididymis and testis were mobilized and pinned aside leading to full microscopic access to the cremaster muscle microcirculation .
cremaster muscle venules were recorded via ccd camera ( cf8/1 , kappa , gleichen , germany ) on a panasonic s - vhs recorder .
postcapillary venules under observation were recorded before and during glucose administration and ranged from 20 to 40  m in diameter .
systemic blood samples ( 10  l ) were taken and assessed for white blood cell count before and after experiment .
systemic blood samples ( 10  l ) were taken after each mab injection and stained with trks solution 1  :  10 ( merck , darmstadt , germany ) . in some experiments , recombinant murine chemokine kc ( keratinocyte - derived chemokine ; peprotech , london , uk ) was injected systemically at a dose of 600  ng per mouse .
systemic leukocyte concentration was analyzed using a hematocytometer and expressed as number of leukocytes per l of whole blood .
microvascular parameters ( venular diameter , venular vessel segment length , and leukocyte rolling velocity ) were measured using an image - processing system .
venular centerline red blood cell velocity was measured during the experiment via a dual photodiode and a digital online cross - correlation program ( circusoft instrumentation , hockessin , usa ) . an empirical factor of 0.625 was used to convert centerline velocities to mean blood flow velocities .
wall shear rates ( w ) were estimated as 4.9 ( 8vb / d ) , where vb is mean blood flow velocity and d the diameter of the vessel [ 20 , 21 ] .   to differentially count intravascular and extravascular leukocytes , cremaster muscle - whole mounts
briefly , while the cremaster muscle was still mounted on the stage for intravital microscopy , the tissue was fixed with 4% paraformaldehyde in 0.1  m phosphate buffer ( ph 7.4 ) . the cremaster muscle was removed and mounted flat on a superfrost glass slide ( menzel , braunschweig , germany ) , air dried for 510  min , and fixed in 4% paraformaldehyde in 0.1  m phosphate buffer ( ph 7.4 ) for 24  h at 4c .
after fixation , the tissue was washed three times in 0.1  m phosphate buffer with 5% ethanol , stained with giemsa ( sigma ) at room temperature for 5  min , and differentiated in 0.01% acetic acid for contrast .
the differentiated slides were washed in water , 75% ethanol , 95% ethanol , 100% ethanol , and fresh xylene , followed by mounting in mounting media ( agar scientific ) .
the giemsa - stained cremaster muscles were observed using a leica dmrb upright microscope and a 25/0,75  na oil immersion objective ( both leica , germany ) .
intravascular and interstitial leukocytes were counted and differentiated into neutrophils , eosinophils , and mononuclear cells . to investigate the endothelial expression of icam1 on unstimulated cremaster muscle venules or during trauma - induced inflammation
, we performed immunohistochemical analysis of whole - mount cremaster muscles as described [ 24 , 25 ] .
briefly , after insertion of a catheter into the carotid artery , primary antibodies against icam1 ( yn-1 , monoclonal rat anti - mouse ; 30  g / mouse , atcc , wesel , germany ) were systemically injected and incubated for 10 minutes .
because of the intravascular antibody application , which was performed before surgical preparation of the cremaster muscle , binding of antibodies is mostly restricted to surface expressed antigens within the vasculature . for unstimulated venules , excess antibody was washed out from the circulation with normal saline solution before the cremaster muscle was obtained . for trauma - stimulated venules ,
washing out of excess antibody occurred after exteriorization of the cremaster muscle and 20 minutes of superfusion with superfusion buffer .
cremaster muscle whole mounts were surgically prepared as reported previously   and transferred onto adhesive slides ( superfrost , menzel , braunschweig , germany ) . after air - drying over 510  min , cremaster muscles were fixed in acetone ( 18c ) overnight .
permeabilization of the tissue was conducted in 0.05  mol / l tris buffer containing 0.003% saponine .
after washing , cremaster muscle tissue was incubated with biotin - conjugated secondary goat anti - rat antibody ( ebioscience , usa ) over 45  min in a humid chamber .
blocking of endogenous peroxidase activity was performed with h2o2 in methanol over 1  h , followed by incubation of the tissue with peroxidase - conjugated streptavidin .
staining of tissue samples was performed using a commercially available kit ( dab , vector lab , burlingame , usa ) . for counter - staining mayer 's hemalaun
thereafter , the samples were incubated with an increasing concentration of alcohol followed by xylene ( carl roth , karlsruhe , germany ) .
sealing of tissue samples was performed with mounting medium ( dpx mounting medium , agar scientific , stansted essex , uk ) .  
analysis of stained slides was conducted on a leica dmrb upright microscope and a 25/0.75  na oil immersion objective ( both leica , wetzlar , germany ) .
photographs of the samples were taken using a color ccd camera ( kappa , germany ) .
after isolation , they were loaded on top of a discontinuous percoll gradient ( 52%/64%/72% ) and centrifuged at 1000  g for 30 minutes .
pmns were harvested from the 64%/72% interface , washed in pbs , and cultivated for 24 hours in rpmi 1640 medium supplemented with 20% wehi-3b - conditioned medium .
pmn viability was greater than 95% as assessed by the trypan blue exclusion test , and purity was greater than 98% as analyzed by microscopy using hemacolor staining ( merck , darmstadt , germany ) .
the expression of mac1 and lfa1 on bone marrow - derived neutrophils was assessed by flow cytometry .
after red blood cell lysis , 10 leukocytes / ml were stimulated for 15  min with 10  mg glucose at 37c .
next , cells were incubated in the dark with fitc - conjugated anti - mac1 mab m1/70 ( 1  g/10 cells , rat igg2b ; ebioscience , san diego , usa ) , fitc - conjugated anti - lfa1 mab m17/4 ( 1  g/10 cells , rat igg2a ; ebioscience , san diego , usa ) , or respective fitc - conjugated isotype control antibodies ( 1  g/10 cells , rat igg2b or rat igg2a ; ebioscience , san diego , usa ) to detect anti - mac1 and anti - lfa1 signals , respectively .
mac1 and lfa1 expression was assessed on 10.000 cells per mouse within the neutrophil cluster defined by forward - side scatter analysis using lsrii with diva software package ( becton dickinson , san jose , usa ) .
expression of mac1 and lfa1 upon stimulation with different glucose concentrations was compared to unstimulated cells and their respective isotype controls .
flow chamber experiments were conducted as described [ 23 , 27 ] . in brief ,
rectangular microglass capillaries ( vitrocom , mountain lakes , usa ) were coated with rmp - selectin ( 2  g / ml ) , rmcxcl1 ( 5  g / ml ) , and icam1 ( 1  g / ml ) and connected via pe tubing to a 2  ml syringe containing freshly isolated bone marrow neutrophils from lysegfp mice . in lysegfp mice the enhanced gfp ( egfp ) is knocked into the murine lysozyme m ( lys ) locus leading to the expression of egfp in myelomonocytic cells .
the cell suspension ( 0.25  10 gfp positive cells ) was perfused through the flow chamber and adhesion of gfp - positive cells observed by fluorescence microscopy ( bx51 wi with a saline immersion objective  20/0.95  na , olympus hamburg ) for 10 minutes under constant flow conditions using a high precision perfusion pump ( harvard instruments , march - hugstetten , germany ; wall shear stress 0.1  pa ) .
images were recorded via a ccd camera system ( cf8hs ; kappa ) on a panasonic s - vhs recorder . in some experiments
, cell suspensions were incubated with d - glucose ( 10  mg/10 cells ) 15 minutes before the perfusion through the flow chamber .
sigma stat 3.5 ( systat software , erkrath , germany ) was used for statistical analysis .
leukocyte counts , vessel diameters , leukocyte adhesion , leukocyte - rolling flux fractions , wall shear rates , and in vitro leukocyte adhesion between groups and treatments were compared with one - way anova followed by a multiple pairwise comparison test ( dunn 's test ) or by wilcoxon rank - sum test , as appropriate .
the first objective of our experiments was triggering a significant increase of the murine blood glucose concentration by intravenous glucose application . as described earlier , stress ( induced by anesthesia and surgical preparation ) resulted in high basal blood glucose levels in all investigated mice . as expected one minute after glucose injection blood glucose concentration increased significantly in a dose - dependent manner ( see supplemental table 1 available online at doi:10.1155/2012/739176 ) .
in contrast , recent studies [ 7 , 8 ] did not detect elevation of systemic blood glucose levels presumably due to different experimental setup ( intraperitoneal injection of glucose and longer - time interval until microscopic observation ) . because we observed a rapid and significant increase of systemic blood glucose concentration after a dose of 0,5  g
/ kg glucose , which is in the range clinically used to treat severe hypoglycemia , we continued with that dose in all further experiments . surgical preparation of the cremaster muscle induces leukocyte adhesion mainly via the chemokine cxcl1-cxcr2 pathway and 2 integrins lfa1 and mac1 in the short - term model of trauma - induced inflammation [ 23 , 27 ] . using this model we analyzed the number of adherent leukocytes in wt mice in postcapillary venules of the cremaster muscle before and after intravenous injection of different doses of glucose .
the results obtained from these experiments were compared to injection of normal saline and l - glucose .
( vascular diameter , blood flow velocity , wall shear rate , and white blood cell count ) before and after glucose or saline injection ( table 1 ) .
thereby , we ruled out that alterations of leukocyte recruitment might be caused by hemodynamic changes in response to fluid injection .
administration of a low dose of 0,25  g / kg glucose did not lead to any significant changes of leukocyte adhesion .
however , increasing doses of glucose ( 0,5  g / kg and 1  g / kg , resp . )
lead to a significant , dose - dependent increase of leukocyte adhesion in wt mice within 15 minutes after glucose administration ( figure 1(a ) ) compared to controls injected with normal saline or l - glucose .
these results suggest that glucose triggers leukocyte adhesion which is not attributable to hemodynamic changes .
to investigate the impact of glucose on neutrophil transmigration , we also performed giemsa staining of whole - mount cremaster muscles in this model and classified leukocytes into neutrophils , eosinophils , and mononuclear cells as described .
accordingly , the number of perivascular neutrophils was higher after administration of glucose compared to saline controls suggesting that glucose - triggered leukocyte adhesion translates into increased transmigration of leukocytes , too ( figures 1(b)1(d ) ) . taken together , leukocyte recruitment during trauma induced inflammation can be rapidly enhanced by intravenous glucose injection . despite different experimental design , this observation is consistent with intravital microscopic studies on mesenterial vessels of schffler et al . , booth et al . , and azcutia et al .
importantly , neither changes of hemodynamic conditions nor osmolarity [ 6 , 8 ] are causative for the observed glucose induced effects .
moreover , there is evidence that glucose triggered leukocyte recruitment is reversible through insulin treatment . as a potent proinflammatory agent ,
we administered tnf in a dose of 500  ng 3  h prior to exteriorization of the cremaster muscle and observed leukocyte adhesion in cremaster muscle venules of wt mice , either treated with glucose or normal saline . in this model ,
transition from leukocyte rolling to firm adhesion after tnf pretreatment is mediated in an overlapping fashion involving cxcr2 and e selectin .
microvascular parameters for the groups are presented in table 2 and show similar vessel diameters , centerline velocities , wall shear rates , and wbc counts .
administration of 0,5  g / kg glucose did not significantly increase leukocyte adhesion in the tnf model when compared to injection of normal saline ( figure 2(a ) ) . to investigate whether glucose alters neutrophil transmigration , we performed giemsa staining of whole mounts of tnf-treated cremaster muscles and classified leukocytes into neutrophils , eosinophils , and mononuclear cells as described . in mice injected with glucose ,
the number of extravasated neutrophils was hardly increased compared to normal saline - treated mice , indicating that proinflammatory stimulation with tnf is not further enhanced by glucose ( figures 2(b)2(d ) ) .
thus , glucose exerts proinflammatory effects with regard to leukocyte recruitment in the short - term trauma model , but not in the long - term tnf model .  
we hypothesize that in contrast to the short term model of trauma - induced inflammation tnf induces a very strong nfb - triggered proinflammatory stimulation over 3h that is not further augmentable by glucose administration .
this theory is supported by the fact that the level of leukocyte adhesion and transmigration is about the same after tnf stimulation compared to trauma - induced inflammation plus glucose .   using icam1-ko and lfa1-ko mice we addressed the question whether icam1 and lfa1 play a role for the observed glucose - induced effects during leukocyte recruitment during trauma - induced inflammation ( hemodynamic and microvascular parameters are presented in table 3 ) . in line with previous reports
[ 31 , 32 ] we found comparable baseline leukocyte adhesion in cremaster muscle venules of wt , lfa1-ko , and icam1-ko mice .
in contrast to wt mice , injection of 0.5  g / kg glucose in icam1 and in lfa1 mice did not lead to significant changes of adherent leukocytes compared to baseline values ( figure 1(a ) ) .
accordingly , transmigration of neutrophils as observed in giemsa - stained cremaster muscle whole mounts of icam1-ko and in lfa1-ko mice was similar after administration of glucose compared to normal saline ( figures 1(b ) , 1(f ) , and 1(g ) ) .
these findings suggest that icam1 and lfa1 are crucially involved in mediating glucose - induced leukocyte recruitment , which is in line with previous observations [ 8 , 33 ] . in order to gain further insight into underlying mechanisms , we next investigated the role of the cxcl1-cxcr2 pathway for glucose - triggered leukocyte recruitment in our experimental setting .
we and others demonstrated that injection of cxcr2-binding chemokine cxcl1 induces a significant increase of leukocyte adhesion which is mostly attributed to lfa1 activation and its subsequent icam1 binding [ 23 , 31 ] .
we first asked whether systemically injection of 600  ng cxcl1 in addition to 0.5  g / kg glucose would be able to further enhance leukocyte adhesion and transmigration during trauma - induced inflammation ( hemodynamic and microvascular parameters are presented in table 3 ) .
however , the number of adherent and transmigrated cells was not further increased in glucose - injected mice after costimulation with cxcl1 compared to glucose injection only ( figures 1(a ) , 1(b ) , and 1(h ) ) , indicating that cxcl1 might be involved in glucose - mediated leukocyte recruitment .
next , we used pertussis toxin ( ptx ) to unspecifically block the chemokine receptor cxcr2 by disruption of g - protein - coupled receptor signaling .
notably , ptx pretreatment completely abolished leukocyte adhesion or transmigration in response to glucose in our experimental model ( figures 1(a ) , 1(b ) , and 1(e ) ) suggesting that the cxcl1-cxcr2 pathway is involved in mediating glucose - induced leukocyte recruitment . to further explore underlying mechanisms for the observed glucose - induced effects we analyzed the expression of the 2 integrins lfa1 and mac1 on neutrophils in response to glucose using flow cytometry .
as depicted in figure 3 , expression of lfa1 and mac1 on bone marrow - derived mouse neutrophils was not altered after incubation with 10  mg / ml glucose for 15 minutes when compared to control neutrophils .
this finding indicates that upregulation of 2 integrins does not account for the observed glucose - induced augmentation of leukocyte recruitment .
therefore , the changes of leukocyte recruitment are unlikely to be attributable to leukocyte - driven mechanism , as signaling of glucose - incubated leukocytes is identical to leukocytes incubated with saline .
glucose - evoked changes of integrin avidity or activity are difficult to exclude in our flow cytometric approach , as respective antibodies are not available in mice .
next , we aimed to further dissect leukocyte- from endothelium - driven mechanisms mediating glucose - induced adhesion of leukocytes and performed flow chamber experiments . therefore , microflow chambers were coated with p selectin , icam1 , and kc and constantly perfused with isolated glucose - stimulated or saline control bone marrow neutrophils of lysegfp mice . under control conditions we observed a significant number of adherent gfp - positive cells ( mainly neutrophils ) in fully coated flow chamber compared to uncoated flow chambers ( figure 4 ) .
noteworthy , glucose stimulation ( 10  mg / ml for 15 minutes ) did not affect leukocyte adhesion in this dynamic flow chamber approach , indicating that leukocyte - born mechanisms are unlikely to be connected to glucose - induced changes of leukocyte recruitment .
we next ask about the impact of glucose on the regulation of endothelial adhesion molecules . since interaction of lfa1 with icam1
is involved in mediation of glucose - induced effects of leukocyte recruitment , we assessed endothelial icam1 expression in postcapillary venules of trauma - stimulated cremaster muscles using immunohistochemistry .
endothelial icam1 expression in cremaster muscle venules of glucose treated mice was significantly increased compared to control mice ( figure 5 , also illustrated by micrographs ) .
these findings confirm previous observations of azcutia et al . and others [ 8 , 33 ] , strongly suggesting that glucose - dependent enhancement of leukocyte recruitment is at least in part entailed to icam1 upregulation .
however , future studies are necessary to investigate whether glucose regulates other endothelial leukocyte adhesion molecules acting in concert with icam1 .
in addition , humoral factors cytokines and chemokines could be involved in the glucose - induced proinflammatory responses , as described by azcutia et al . and ling et al .
based on our presented results we hypothesize that glucose induces cxcl1-cxcr2-dependent activation of lfa1 which in turn binds to upregulated icam1 in order to mediate leukocyte recruitment . however , up to date it remains unclear whether and how glucose - dependent signaling , that is , glucose receptors or channels are involved in upstream signalling pathways .   to our knowledge , this is the first study that investigated the immediate effects of intravenously administered glucose on the leukocyte recruitment cascade in vivo , so that our results may stimulate future studies further investigating underlying mechanisms of the observed glucose - dependent proinflammatory signaling .
leukocyte adhesion and transmigration are strongly augmented by intravenous glucose injection during trauma - induced inflammation but not during 3h - tnf stimulation .
the glucose - induced leukocyte recruitment is mediated by cxcl1-triggered interaction of lfa1 and icam1 .
thus , our results also indicate that the proinflammatory properties of glucose are stimulus - dependent and might open new perspectives for the development of strategies targeting hyperglycemia - related inflammatory conditions .
 it is well acknowledged that proinflammatory stimulation during acute hyperglycemia is able to aggravate inflammatory diseases . 
 however , the mechanisms of proinflammatory effects of glucose are controversially discussed . 
 we investigated leukocyte recruitment after intravenous injection of glucose in different inflammatory models using intravital microscopy . 
 flow chamber experiments , expression analysis , functional depletion , and knockout of key adhesion molecules gave mechanistic insight in involved pathways . 
 
 we demonstrated that a single injection of glucose rapidly increased blood glucose levels in a dose - dependent manner . 
 notably , during tumor necrosis factor ( tnf ) -induced inflammation leukocyte recruitment was not further enhanced by glucose administration , whereas glucose injection profoundly augmented leukocyte adhesion and transmigration into inflamed tissue in the trauma model , indicating that proinflammatory properties of glucose are stimulus dependent . 
 experiments with functional or genetic inhibition of the chemokine receptor cxcr2 , intercellular adhesion molecule 1 ( icam1 ) , and lymphocyte function antigen 1 ( lfa1 ) suggest that keratino - derived - chemokine cxcl1-triggered interactions of icam1 and lfa1 are crucially involved in the trauma model of inflammation . 
 the lacking effect of glucose on 2 integrin expression and on leukocyte adhesion in dynamic flow chamber experiments argues against leukocyte - driven underlying mechanisms and favours an endothelial pathway since endothelial icam1 expression was significantly upregulated in response to glucose . 
1. Introduction
2. Materials and Methods
3. Results and Discussion
4. Conclusion