Andrej Khandoga

Technische Universität München, München, Bavaria, Germany

Are you Andrej Khandoga?

Claim your profile

Publications (42)230.69 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Background: Early allograft dysfunction after liver transplantation (LTX) is not well defined. The aim of this study was to evaluate the value of early post-transplant model for end-stage liver disease (MELD) scores for predicting long-term outcome after transplantation. Methods: In this single-center retrospective study, 362 consecutive patients after LTX were included. MELD scores at 7, 14, and 21 postoperative days (PODs) were calculated from primary lab values. Receiver operating characteristic (ROC) analyses were carried out to determine the critical cutoff MELD scores for patient and graft survival. Results: One year after transplantation, the patient and graft survival rates were 85 and 69%, respectively. Although pretransplant MELD scores were similar, they were significantly different at POD7, POD14, and POD21 between patients who died and those who survived the first year after transplantation. As shown by ROC curves, for patient survival, the optimal time point is POD14 with a cutoff MELD of 17. At this time point, patients with a MELD below 17 showed a 1-year survival rate of 94.3% and patients with a MELD of 17 and higher showed a 1-year survival rate of only 75.4%. For graft survival, the optimal time point was day 7 and a cutoff MELD of 29 (92% at MELD<29; 56.4% at MELD≥29). A multivariate analysis of potential risk factors indicated a significant role of serum bilirubin and MELD score determined on POD14 for patient survival. Conclusion: In conclusion, early postoperative MELD scores predict outcome after LTX. The postoperative MELD score at POD14 is a good predictor for patient survival and at POD7 for the graft survival after LTX.
    European journal of gastroenterology & hepatology 11/2015; DOI:10.1097/MEG.0000000000000505 · 2.25 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Programmed necrosis (necroptosis), a newly discovered form of cell death is mediated by Receptor-Interacting Protein (RIP1) and plays a pivotal role after myocardial, renal, and cerebral ischemia-reperfusion (I/R). The relevance of necroptosis in the postischemic liver remains, however, unclear. The aim of this study was to analyze the role of programed necrosis during hepatic I/R. C57BL6 mice were subjected to warm hepatic I/R (90min/240min). The animals were pretreated either with the RIP1 inhibitor necrostatin-1 (Nec-1; 3.5μg/kg) or vehicle (Nec-1inactive; 3.5μg/kg) administered systemically prior ischemia. Sham-operated animals served as controls (n=6 each group). The inflammatory response was evaluated by intravital microscopy. The hepatic transaminases ALT/AST in plasma as well as the activity of caspase-3 in tissue were determined as markers of hepatocellular injury. Leukocyte recruitment to the liver, sinusoidal perfusion failure as well as the transaminase activities were strongly increased upon I/R as compared to the sham-operated mice. Inhibition of the RIP1-dependent pathway with Nec-1, however, did not attenuate I/R-induced leukocyte migration, perfusion failure, and hepatocellular injury. Western-Blot analysis showed a baseline RIP1 expression in livers from sham-operated mice, whereas RIP1 expression was not detectable in both Nec-1-treated and vehicle-treated I/R group. Caspase-3 activity was significantly elevated after I/R in both postischemic groups. Our in vivo data show that i) RIP1-mediated necroptosis is not present in the postischemic liver, ii) I/R-induced caspase activation is associated with loss of RIP1 expression. Since caspases are able to cleave RIP1, we hypothesize that I/R-triggered caspase activation negatively regulates necroptosis and, thereby, determines apoptosis as a preferred route of the cell death after hepatic I/R.
    Shock (Augusta, Ga.) 05/2015; 44(1). DOI:10.1097/SHK.0000000000000371 · 3.05 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Background: CD4+ T cells play a critical role during hepatic ischemia-reperfusion (I/R) injury although the mechanisms of their migration in the postischemic liver remain unclear. We answered the questions of whether hepatic stellate cells (HSCs) interact with CD4+ T cells during I/R of the liver and whether modulation of HSC activity affects T cell-dependent I/R injury. Methods: In mice, migration of CD4+ T cells was analyzed in vivo using conventional intravital microscopy and two-photon microscopy. CD4+ T cell-HSC interactions were visualized after infusion of fluorescence-labeled CD4+ T cells into Cx3CR1 mice (mice exhibiting GFP-labeled HSCs) after I/R. Because the activation of HSC is controlled by endocannabinoid receptors, CB-1 and CB-2, the mice received treatment before I/R with the CB-2 agonist JWH-133 to reach HSC depletion or the CB-1 agonist arachidonylcyclopropylamide to activate HSCs. Sinusoidal perfusion and liver transaminases were used as markers of I/R injury. Results: Hepatic I/R induced CD4+ T cell recruitment in sinusoids. More than 25% of adherent CD4+ T cells were colocalized with HSCs during reperfusion, suggesting a direct cell-cell interaction. The HSC deactivation with JWH-133 significantly attenuated the CD4+ T cell recruitment in the postischemic liver and reduced I/R injury as compared to the vehicle-treated group. The HSC hyperactivation by CB-1, however, did not affect T-cell migration and even increased perfusion failure. Conclusion: Our in vivo data suggest that CD4+ T cells interact with HSCs on their migration into the hepatic parenchyma, and a depletion or deactivation of HSCs protects the liver from T cell-dependent I/R injury.
    Transplantation 10/2014; 99(1). DOI:10.1097/TP.0000000000000461 · 3.83 Impact Factor
  • M Rentsch · M Runge · M Thomas · M Drefs · J Andrassy · A Khandoga · C Trumm · A Muacevic · M Guba · J Werner ·

    Zeitschrift für Gastroenterologie 08/2014; 52(08). DOI:10.1055/s-0034-1386378 · 1.05 Impact Factor
  • M Drefs · M Thomas · A Khandoga · F Haak · J Andrassy · M Guba · J Werner · M Rentsch ·

    Zeitschrift für Gastroenterologie 08/2014; 52(08). DOI:10.1055/s-0034-1386379 · 1.05 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Background: Augmenter of Liver Regeneration (ALR), a protein synthesized in the liver is suggested to be protective against oxidative stress-induced cell death. Hepatic ischemia-reperfusion (I/R) injury is triggered by reactive oxygen species. Here, we tested the hypothesis that ALR attenuates hepatic I/R injury in vivo. Methods: C57BL6 mice were subjected to warm hepatic ischemia for 90 min. Either recombinant ALR (100 μg/kg) or vehicle were administered to mice prior ischemia. During reperfusion, neutrophil and CD4+ T cell migration and sinusoidal perfusion were analyzed using intravital microscopy. Alanine aminotransferase-aspartate aminotransferase (plasma) and caspase-3 (tissue) activities were determined as markers of hepatocellular necrotic and apoptotic injury. Results: Hepatic I/R led to dramatic enhancement of neutrophil and CD4+ T cell recruitment in hepatic microvessels, sinusoidal perfusion failure, and strong elevation of aspartate aminotransferase-alanine aminotransferase and caspase-3 activities. During early reperfusion (60 min), the pretreatment with ALR improved postischemic perfusion failure (P < 0.05) and attenuated liver enzyme activities. Recruitment of CD4+ T cells, but not of neutrophils was attenuated. After 240 min of reperfusion, the protective effect of ALR was stronger, since the liver enzyme activity, perfusion failure, and leukocyte influx were significantly attenuated. As shown by the measurement of caspase-3 activity, postischemic apoptosis was reduced in the ALR-treated group. Conclusions: Our in vivo data show that ALR has a therapeutic potential against postischemic liver injury. As a mechanism, we suggest a direct protective effect of ALR on apoptotic and necrotic death of hepatocytes and an attenuation of inflammatory cell influx into the postischemic tissue.
    Journal of Surgical Research 05/2014; 192(1). DOI:10.1016/j.jss.2014.05.026 · 1.94 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Neutrophil infiltration of the postischemic tissue considerably contributes to organ dysfunction on ischemia/reperfusion injury. Beyond its established role in fibrinolysis, tissue-type plasminogen activator (tPA) has recently been implicated in nonfibrinolytic processes. The role of this serine protease in the recruitment process of neutrophils remains largely obscure. Using in vivo microscopy on the postischemic cremaster muscle, neutrophil recruitment and microvascular leakage, but not fibrinogen deposition at the vessel wall, were significantly diminished in tPA(-/-) mice. Using cell transfer techniques, leukocyte and nonleukocyte tPA were found to mediate ischemia/reperfusion-elicited neutrophil responses. Intrascrotal but not intra-arterial application of recombinant tPA induced a dose-dependent increase in the recruitment of neutrophils, which was significantly higher compared with stimulation with a tPA mutant lacking catalytic activity. Whereas tPA-dependent transmigration of neutrophils was selectively reduced on the inhibition of plasmin or gelatinases, neutrophil intravascular adherence was significantly diminished on the blockade of mast cell activation or lipid mediator synthesis. Moreover, stimulation with tPA caused a significant elevation in the leakage of fluorescein isothiocyanate dextran to the perivascular tissue, which was completely abolished on neutrophil depletion. In vitro, tPA-elicited macromolecular leakage of endothelial cell layers was abrogated on the inhibition of its proteolytic activity. Endogenously released tPA promotes neutrophil transmigration to reperfused tissue via proteolytic activation of plasmin and gelatinases. As a consequence, tPA on transmigrating neutrophils disrupts endothelial junctions allowing circulating tPA to extravasate to the perivascular tissue, which, in turn, amplifies neutrophil recruitment through the activation of mast cells and release of lipid mediators.
    Arteriosclerosis Thrombosis and Vascular Biology 04/2014; 34(7). DOI:10.1161/ATVBAHA.114.303721 · 6.00 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Platelets play a critical role during hepatic ischemia/reperfusion (I/R). Antiplatelet strategies during liver transplantation are, however, limited because of bleeding complications. Thrombin is activated during reperfusion and regulates platelet and endothelial cell function via protease-activated receptor 4 (PAR-4). Interventions at the level of PAR-4, the main platelet receptor for thrombin, are assumed to attenuate the proinflammatory effects of thrombin without affecting blood coagulation. The aim of our study was to analyze the impact of PAR-4 blockade on platelet recruitment and microvascular injury during hepatic I/R. C57BL/6 mice undergoing hepatic I/R (90 min/60 min and 240 min) were treated either with a selective PAR-4 antagonist TcY-NH2 or vehicle. Sham-operated animals served as controls. Recruitment of freshly isolated and fluorescence-labeled platelets and CD4 T cells was analyzed using intravital video fluorescence microscopy. Parameters of tissue injury, regeneration, and blood coagulation were assessed in tissue/blood samples. Results show that treatment with TcY-NH2 attenuated I/R-induced platelet and CD4 T-cell recruitment, improved sinusoidal perfusion failure, and reduced apoptotic and necrotic injury. The protective effect of PAR-4 blockade did not suppress hemostasis or liver regeneration. Our in vivo data suggest PAR-4 as a potential target for future therapeutic strategies against platelet-mediated liver injury on transplantation.
    Transplantation 01/2014; 97(2):154-60. DOI:10.1097/01.TP.0000437430.89485.a0 · 3.83 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: De novo malignancies are a major cause of late death after liver transplantation. Aim of the present study was to determine whether use of cyclosporine versus tacrolimus affects long-term tumor incidence considering potential confounders. De novo malignancies in 609 liver transplant recipients at Munich Transplant Centre between 1985 and 2007 were registered. In 1996, the standard immunosuppressive regimen was changed from cyclosporine to tacrolimus. Different effects of those drugs on long-term tumor incidence were analyzed in multivariate analysis. During 3765 patient years of follow-up (median 4.78 years), 87 de novo malignancies occurred in 71 patients (mean age 47.5 ± 13.3 years, mean time after liver transplantation 5.7 ± 3.7 years). The cumulative incidence of de novo malignancies was 34.7% for all tumor entities after 15 years as compared to 8.9% for a nontransplanted population. The most frequent tumors observed were nonmelanoma skin cancers (44.83%). Moreover, post-transplant lymphoid disease, oropharyngeal cancer (n = 6, 6.9%), upper gastrointestinal tract cancer (n = 4, 4.6%), lung cancer (n = 4, 4.6%), gynecological malignancies (n = 4, 4.6%), and kidney cancer (n = 3, 3.45%) were detected. Multivariate analysis revealed recipient age [hazards ratio (HR) 1.06], male gender (HR 1.73), and tacrolimus-based immunosuppression (HR 2.06) as significant risk factors. Based on those results, a tacrolimus-based immunosuppression should be discussed especially in older male patients. Whether reducing tacrolimus target levels may reduce the risk for de novo malignancies has yet to be determined in prospective trials.
    Transplant International 07/2013; 26(10). DOI:10.1111/tri.12165 · 2.60 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Urokinase-type plasminogen activator (uPA) has recently been implicated in the pathogenesis of ischemia-reperfusion (I/R) injury. The underlying mechanisms remain largely unclear. Using in vivo microscopy on the mouse cremaster muscle, I/R-elicited firm adherence and transmigration of neutrophils were found to be significantly diminished in uPA-deficient mice and in mice treated with the uPA inhibitor WX-340, but not in uPA receptor (uPAR)-deficient mice. Interestingly, postischemic leukocyte responses were significantly reduced on blockade of the integrin CD11b/Mac-1, which also serves as uPAR receptor. Using a cell transfer technique, postischemic adherence and transmigration of wild-type leukocytes were significantly decreased in uPA-deficient animals, whereas uPA-deficient leukocytes exhibited a selectively reduced transmigration in wild-type animals. On I/R or stimulation with recombinant uPA, >90% of firmly adherent leukocytes colocalized with CD31-immunoreactive endothelial junctions as detected by in vivo fluorescence microscopy. In a model of hepatic I/R, treatment with WX-340 significantly attenuated postischemic neutrophil infiltration and tissue injury. Our data suggest that endothelial uPA promotes intravascular adherence, whereas leukocyte uPA facilitates the subsequent paracellular transmigration of neutrophils during I/R. This process is regulated via CD11b/Mac-1, and does not require uPAR. Pharmacological blockade of uPA interferes with these events and effectively attenuates postischemic tissue injury.
    Circulation 10/2011; 124(17):1848-59. DOI:10.1161/CIRCULATIONAHA.110.017012 · 14.43 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Leukocyte extravasation depends on various adhesion receptors at endothelial cell contacts. Here we have analyzed how mouse CD99 and CD99L2 cooperate with PECAM-1. We found that antibodies against mouse CD99 and PECAM-1 trap neutrophils between endothelial cells in in vitro transmigration assays. A sequential function, as has been suggested for human PECAM-1 and CD99, could not be demonstrated. In contrast to these in vitro results, blocking CD99 or CD99L2 or gene disruption of PECAM-1 trapped neutrophils in vivo between endothelial cells and the underlying basement membrane as revealed by electron microscopy and by 3-dimensional confocal fluorescence microscopy in the inflamed cremaster tissue. Leukocyte extravasation was inhibited in interleukin-1beta-inflamed peritoneum and in the cremaster by PECAM-1 gene disruption and was further attenuated by blocking antibodies against CD99 and CD99L2. In addition, CD99 and CD99L2 were required for leukocyte extravasation in the cremaster after stimulation with tumor necrosis factor-alpha, where the need for PECAM-1 is known to be bypassed. We conclude that CD99 and CD99L2 act independently of PECAM-1 in leukocyte extravasation and cooperate in an independent way to help neutrophils overcome the endothelial basement membrane.
    Blood 08/2010; 116(7):1172-84. DOI:10.1182/blood-2009-12-256388 · 10.45 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: This study was designed to investigate the role of endothelial cell-selective adhesion molecule (ESAM), a recently discovered receptor expressed in endothelial tight junctions and platelets, for leukocyte migration in inflamed liver. The role of ESAM for leukocyte migration in the liver was analyzed using ESAM-deficient mice in a model of warm hepatic ischemia-reperfusion (90min/30-360min). As shown by immunostaining, ESAM is expressed in sinusoids as well as in venules and is not upregulated upon I/R. Emigrated leukocytes were quantified in tissue sections. Postischemic neutrophil transmigration was significantly attenuated in ESAM-/- mice after 2h of reperfusion, whereas it was completely restored after 6h. In contrast, T-cell migration did not differ between ESAM+/+ and ESAM-/- mice. Using intravital microscopy, we demonstrate that ESAM deficiency attenuates I/R-induced vascular leakage after 30min of reperfusion. The I/R-induced elevation in AST/ALT activity, the sinusoidal perfusion failure, and the number of TUNEL-positive hepatocytes were comparable between ESAM+/+ and ESAM-/- mice. ESAM is expressed in the postischemic liver and mediates neutrophil but not T-cell transmigration during early reperfusion. ESAM deficiency attenuates I/R-induced vascular leakage and does not affect leukocyte adherence. Despite the effect on neutrophil migration, ESAM-deficiency does not protect from I/R-induced injury.
    Journal of Hepatology 03/2009; 50(4):755-65. DOI:10.1016/j.jhep.2008.11.027 · 11.34 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Directional migration of transmigrated leukocytes to the site of injury is a central event in the inflammatory response. Here, we present an in vivo chemotaxis assay enabling the visualization and quantitative analysis of subtype-specific directional motility and polarization of leukocytes in their natural 3D microenvironment. Our technique comprises the combination of i) semi-automated in situ microinjection of chemoattractants or bacteria as local chemotactic stimulus, ii) in vivo near-infrared reflected-light oblique transillumination (RLOT) microscopy for the visualization of leukocyte motility and morphology, and iii) in vivo fluorescence microscopy for the visualization of different leukocyte subpopulations or fluorescence-labeled bacteria. Leukocyte motility parameters are quantified off-line in digitized video sequences using computer-assisted single cell tracking. Here, we show that perivenular microinjection of chemoattractants [macrophage inflammatory protein-1α (MIP-1α/Ccl3), platelet-activating factor (PAF)] or E. coli into the murine cremaster muscle induces target-oriented intravascular adhesion and transmigration as well as polarization and directional interstitial migration of leukocytes towards the locally administered stimuli. Moreover, we describe a crucial role of Rho kinase for the regulation of directional motility and polarization of transmigrated leukocytes in vivo. Finally, combining in vivo RLOT and fluorescence microscopy in Cx3CR1gfp/gfp mice (mice exhibiting green fluorescent protein-labeled monocytes), we are able to demonstrate differences in the migratory behavior of monocytes and neutrophils. Taken together, we propose a novel approach for investigating the mechanisms and spatiotemporal dynamics of subtype-specific motility and polarization of leukocytes during their directional interstitial migration in vivo.
    PLoS ONE 02/2009; 4(3):e4693. DOI:10.1371/journal.pone.0004693 · 3.23 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Ischemia-reperfusion (I/R) activates innate immunity involving Toll-like receptor (TLR) 2 and TLR-4 signaling. Leukocyte migration and vascular permeability contribute to postischemic tissue damage. We hypothesized that TLR-2 and TLR-4 directly mediate leukocyte migration and vascular permeability during I/R. We used in vivo microscopy on postischemic murine cremaster muscle to quantify leukocyte adhesion as well as transendothelial and interstitial migration in sham-operated wild-type mice and in wild-type, TLR-2(-/-), and TLR-4-mutant mice 30 and 120 min after I/R. Alterations in fluorescein isothiocyanate-dextran leakage across cremasteric venules were determined as a measure of endothelial permeability. I/R-induced leukocyte adhesion in TLR-2(-/-) and TLR-4-mutant mice was comparable to that in wild-type mice. The number of transmigrated leukocytes was increased upon I/R in wild-type mice as compared with the sham-operated group. In contrast, leukocyte transmigration was significantly attenuated in TLR-2(-/-) but not in TLR-4-mutant mice. Motility and polarization of interstitially migrating leukocytes did not significantly differ in TLR-2(-/-) and TLR-4-mutant mice from wild-type mice. Postischemic vascular leakage was significantly lower in both TLR-2(-/-) and TLR-4-mutant than in wild-type mice. We conclude that both TLR-2 signaling and TLR-4 signaling enhance postischemic vascular permeability and that TLR-2 has additional effects on the transendothelial migration of leukocytes at the postischemic vascular wall.
    Shock (Augusta, Ga.) 12/2008; 31(6):592-8. DOI:10.1097/SHK.0b013e318193c859 · 3.05 Impact Factor
  • Marc Hanschen · Stefan Zahler · Fritz Krombach · Andrej Khandoga ·
    [Show abstract] [Hide abstract]
    ABSTRACT: Mechanisms mediating CD4+ T-cell recruitment during alloantigen-independent hepatic ischemia-reperfusion (I/R) remain not fully understood. We hypothesized that Kupffer cells activate CD4+ T-cells in the postischemic liver, by the release of free oxygen radicals and cytokines. Recruitment of freshly isolated and fluorescence-labeled CD4+ T-cell was analyzed after hepatic I/R (90/30-120 min) using intravital microscopy in sham-operated mice, in mice after hepatic I/R and in postischemic groups after Kupffer cell depletion, after treatment with antioxidant glutathione, in interleukin (IL)-6-/- mice; and in wild-type mice after infusion of tumor necrosis factor (TNF) receptor-1-/-CD4+ T-cells. Using flow cytometry and immunohistochemistry, we assessed whether Kupffer cell-derived mediators activate CD4+ T-cells and sinusoidal endothelial cells. The clearance kinetics of fluorescence-labeled latex beads was determined as a marker of Kupffer cell activity in vivo. I/R-induced accumulation of CD4+ T-cells in hepatic sinusoids was significantly attenuated on Kupffer cell depletion, after scavenging of free radicals and after interruption of the IL-6- and TNF-alpha-dependent pathways. These mediators directly activate CD4+ T-cells and up-regulated the expression of T cell-relevant adhesion molecules on sinusoidal endothelial cells. Postischemic activity of Kupffer cells was significantly impaired in wild-type mice, and was even more depressed in CD4-/- animals. Kupffer cells trigger recruitment of CD4+ T-cells in the postischemic liver by the release of reactive oxygen species, IL-6, and TNF-alpha. These mediators are capable of activating CD4+ T-cells and sinusoidal endothelial cells. CD4+ T-cells, in turn, influence the activation of Kupffer cells.
    Transplantation 10/2008; 86(5):710-8. DOI:10.1097/TP.0b013e3181821aa7 · 3.83 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In the present study, the role of gelatinases [matrix metalloproteinase-2 and -9 (MMP-2 and -9)] for leukocyte rolling, adherence, and transmigration was analyzed in the mouse cremaster muscle under different inflammatory conditions including ischemia-reperfusion (I/R) and stimulation with MIP-1alpha or platelet-activating factor (PAF). Using zymography, we detected a significant elevation of MMP-9 activity in response to the stimuli applied, and MMP-2 expression was not altered. However, treatment with a specific MMP-2/-9 inhibitor significantly abrogated elevated MMP-9 activity. As observed by intravital microscopy, all inflammatory conditions induced a significant increase in numbers of adherent and transmigrated leukocytes (>80% Ly-6G(+) neutrophils). Blockade of gelatinases significantly diminished I/R- and MIP-1alpha-induced leukocyte adherence and subsequent transmigration, and upon stimulation with PAF, gelatinase inhibition had no effect on leukocyte adherence but selectively reduced leukocyte transmigration. Concomitantly, we observed an increase in microvascular permeability after I/R and upon stimulation with MIP-1alpha or PAF, which was almost completely abolished in the inhibitor-treated groups. Using immunofluorescence staining and confocal microscopy, discontinuous expression of collagen IV, a major substrate of gelatinases within the perivascular basement membrane (BM), was detected in postcapillary venules. Analysis of intensity profiles demonstrated regions of low fluorescence intensity, whose size was enlarged significantly after I/R and upon stimulation with MIP-1alpha or PAF as compared with unstimulated controls. However, this enlargement was abolished significantly after inhibition of gelatinases, respectively. In conclusion, these data demonstrate that gelatinases strictly regulate microvascular permeability and BM remodeling during the early inflammatory response, whereas concomitant leukocyte recruitment is mediated by these proteases in a stimulus-specific manner.
    Journal of Leukocyte Biology 04/2008; 83(4):864-74. DOI:10.1189/jlb.1007666 · 4.29 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Junctional adhesion molecule-A (JAM-A) is a transmembrane protein expressed at tight junctions of endothelial and epithelial cells and on the surface of platelets and leukocytes. The role of JAM-A in leukocyte transmigration in vivo was directly investigated by intravital microscopy using both a JAM-A-neutralizing monoclonal antibody (mAb) (BV-11) and JAM-A-deficient (knockout [KO]) mice. Leukocyte transmigration (but not adhesion) through mouse cremasteric venules as stimulated by interleukin 1beta (IL-1beta) or ischemia/reperfusion (I/R) injury was significantly reduced in wild-type mice treated with BV-11 and in JAM-A KO animals. In contrast, JAM-A blockade/genetic deletion had no effect on responses elicited by leukotriene B(4) (LTB(4)) or platelet-activating factor (PAF). Furthermore, using a leukocyte transfer method and mice deficient in endothelial-cell JAM-A, evidence was obtained for the involvement of endothelial-cell JAM-A in leukocyte transmigration mediated by IL-1beta. Investigation of the functional relationship between JAM-A and PECAM-1 (CD31) determined that dual blockade/deletion of these proteins does not lead to an inhibitory effect greater than that seen with blockade/deletion of either molecule alone. The latter appeared to be due to the fact that JAM-A and PECAM-1 can act sequentially to mediate leukocyte migration through venular walls in vivo.
    Blood 10/2007; 110(6):1848-56. DOI:10.1182/blood-2006-09-047431 · 10.45 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: CD99 is a long-known leukocyte antigen that does not belong to any of the known protein families. It was recently found on endothelial cells, where it mediates transendothelial migration of human monocytes and lymphocyte recruitment into inflamed skin in the mouse. Here, we show that CD99L2, a recently cloned, widely expressed antigen of unknown function with moderate sequence homology to CD99, is expressed on mouse leukocytes and endothelial cells. Using antibodies, we found that CD99L2 and CD99 are involved in transendothelial migration of neutrophils in vitro and in the recruitment of neutrophils into inflamed peritoneum. Intravital and electron microscopy of cremaster venules revealed that blocking CD99L2 inhibited leukocyte transmigration through the vessel wall (diapedesis) at the level of the perivascular basement membrane. We were surprised to find that, in contrast to CD99, CD99L2 was not relevant for the extravasation of lymphocytes into inflamed tissue. Although each protein promoted cell aggregation of transfected cells, endothelial CD99 and CD99L2 participated in neutrophil extravasation independent of these proteins on neutrophils. Our results establish CD99L2 as a new endothelial surface protein involved in neutrophil extravasation. In addition, this is the first evidence for a role of CD99 and CD99L2 in the process of leukocyte diapedesis in vivo.
    Blood 07/2007; 109(12):5327-36. DOI:10.1182/blood-2006-08-043109 · 10.45 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Diabetic nephropathy is associated with interstitial macrophage infiltrates, but their contribution to disease progression is unclear. We addressed this question by blockade of chemokine receptor (CCR)1 because CCR1 mediates the macrophage recruitment to the renal interstitium. In fact, when CCR1 was blocked with BL5923, a novel orally available CCR1 antagonist, the interstitial recruitment of ex vivo labeled macrophages was markedly decreased in uninephrectomized male db/db mice with advanced diabetic nephropathy. Likewise, BL5923 (60 mg/kg, twice a day) orally administered from months 5 to 6 of life reduced the numbers of interstitial macrophages in uninephrectomized db/db mice. This was associated with reduced numbers of Ki-67 proliferating tubular epithelial and interstitial cells, tubular atrophy, and interstitial fibrosis in uninephrectomized db/db mice. Glomerular pathology and proteinuria were not affected by the CCR1 antagonist. BL5923 reduced renal mRNA expression of Ccl2, Ccr1, Ccr2, Ccr5, transforming growth factor-beta1, and collagen I-alpha1 when compared with untreated uninephrectomized male db/db mice of the same age. Thus, we identified a previously unrecognized role for interstitial macrophages for tubulointerstitial injury, loss of peritubular microvasculature, interstitial inflammation, and fibrosis in type 2 diabetic db/db mice. These data identify oral treatment with the CCR1 antagonist BL5923 as a potential therapy for late-stage diabetic nephropathy.
    American Journal Of Pathology 04/2007; 170(4):1267-76. DOI:10.2353/ajpath.2007.060937 · 4.59 Impact Factor

  • Vascular Pharmacology 09/2006; 45(3). DOI:10.1016/j.vph.2006.08.221 · 3.64 Impact Factor

Publication Stats

1k Citations
230.69 Total Impact Points


  • 2005-2014
    • Technische Universität München
      München, Bavaria, Germany
  • 2004-2014
    • Ludwig-Maximilians-University of Munich
      • Department of Surgery
      München, Bavaria, Germany
  • 2010
    • Max Planck Institute for Molecular Biomedicine
      Muenster, North Rhine-Westphalia, Germany
  • 2007
    • University of Münster
      • Institute of Cell Biology
      Münster, North Rhine-Westphalia, Germany