B. A. Yard

Impact of Donor Dopamine on Immediate Graft Function after Kidney Transplantation

Optimizing medical donor management may have a considerable impact on transplantation outcome. This study investigated the effect of donor dopamine on initial graft function in renal allograft recipients, involving 254 consecutive recipients of a cadaver kidney, aged 18–74 years, transplanted between 1990 and 2003. Immunosuppression was based on cyclosporine. Patients were grouped according to donor use of dopamine during intensive care. Delayed graft function (DGF), and serial creatinine concentrations were compared between the groups. Dopamine‐treated and ‐untreated donors were very similar regarding hemodynamics and renal function. Delayed graft function occurred in 47/158 treated and 48/96 untreated kidneys (p = 0.001). Donor dopamine was associated with a more rapid decrease of s‐creatinine, which became obvious on the first postoperative day. Of patients in the treated and untreated group, respectively, 81.9% and 65.8% reached a s‐creatinine level less than 2 mg/dL during the first month (p = 0.005). Donor dopamine remained predictive of a normalized s‐creatinine level [HR 1.71; 95% CI 1.22–2.41] after controlling for confounding factors by multivariate Cox regression. Donor dopamine is associated with improvements of initial graft function after kidney transplantation. The beneficial effect of dopamine is achievable without side‐effects for the recipients, and correlates with superior long‐term graft survival.

The clinical significance of allospecific antibodies against endothelial cells detected with an antibody-dependent cellular cytotoxicity assay for vascular rejection and graft loss after renal transplantation.

Serum samples of 64 consecutive patients who underwent renal transplantation in our institution were examined for the presence of antibody-dependent cellular cytotoxicity (ADCC) activity against endothelial cells (EC). From each patient serum samples were obtained immediately before transplantation and 1 week, 1 month and 1 year thereafter. The results were evaluated in the context of tests to measure donor-specific humoral immunity against lymphocytes and monocytes, and related to parameters of presensitization, graft survival, and histology. Sera from 10 patients were positive for ADCC on a panel of HLA-typed endothelial cells. In 8 patients sera were already positive before transplantation and remained positive thereafter. In 4 patients a positive crossmatch with donor T and B cells and monocytes could be observed after transplantation. In only one patient were these crossmatches positive before transplantation. A significant correlation was found between ADCC positivity and vascular rejection (P=0.015); in addition graft survival was significantly better in the ADCC negative group vs. the positive group (P=0.0004). These data demonstrate the significance of allospecific anti EC antibodies for the occurrence of vascular rejection and graft loss after renal transplantation.

Rosiglitazone Reduces Angiotensin II and Advanced Glycation End Product-dependent Sustained Nuclear Factor-κB Activation in Cultured Human Proximal Tubular Epithelial Cells

Tubular damage is a major feature in the development of diabetic nephropathy. This study investigates the effects of the thiazolidindione rosiglitazone on angiotensin II and advanced glycation end product-induced tubular activation in human proximal tubular epithelial cells IN VITRO. Angiotensin II and advanced glycation end products, both induced a dose-dependent sustained activation of the redox-sensitive transcription factor, Nuclear Factor KAPPA B (NF-kappaB). Nuclear translocation of NF-kappaB was evident already after one hour and persistent for more than four days. Co-incubation of proximal tubular epithelial cells with rosiglitazone significantly reduced angiotensin II and advanced glycation end product-mediated generation of reactive oxygen species, angiotensin II-dependent advanced glycation end product formation, NF-kappaB activation, and NF-kappaB-dependent pro inflammatory gene expression. Most importantly, rosiglitazone effects on NFkappaB activation were maximal at later time points, indicating that rosiglitazone treatment confers long lasting renoprotective effects.

Heterogeneity in lipopolysaccharide responsiveness of endothelial cells identified by gene expression profiling: role of transcription factors

Interindividual differences of endothelial cells in response to endotoxins might contribute to the diversity in clinical outcome among septic patients. The present study was conducted to test the hypothesis that endothelial cells (EC) with high and low proinflammatory potential exist and to dissect the molecular basis underlying this phenomenon. Thirty human umbilical vein endothelial cell (HUVEC) lines were stimulated for 24u2003h with lipopolysaccharide (LPS) and screened for interleukin (IL)‐8 production. Based on IL‐8 production five low and five high producers, tentatively called types I and II responders, respectively, were selected for genome‐wide gene expression profiling. From the 74 genes that were modulated by LPS in all type II responders, 33 genes were not influenced in type I responders. Among the 41 genes that were increased in both responders, 17 were expressed significantly stronger in type II responders. Apart from IL‐8, significant differences in the expression of proinflammatory related genes between types I and II responders were found for adhesion molecules [intercellular adhesion molecule (ICAM‐1), E‐selectin)], chemokines [monocyte chemoattractant protein (MCP‐1), granulocyte chemotactic protein (GCP‐2)], cytokines (IL‐6) and the transcription factor CCAAT/enhancer binding protein‐delta (C/EBP‐δ). Type I responders also displayed a low response towards tumour necrosis factor (TNF)‐α. In general, maximal activation of nuclear factor (NF)‐κB was achieved in type I responders at higher concentrations of LPS compared to type II responders. In the present study we demonstrate that LPS‐mediated gene expression differs quantitatively and qualitatively in types I and II responders. Our results suggest a pivotal role for common transcription factors as a low inflammatory response was also observed after TNF‐α stimulation. Further studies are required to elucidate the relevance of these findings in terms of clinical outcome in septic patients.

Imatinib mesylate, a new kid on the block for the treatment of anti‐neutrophil cytoplasmic autoantibodies‐associated vasculitis?

Persistent T cell activation is a common finding in anti‐neutrophil cytoplasmic autoantibodies (ANCA)‐associated systemic vasculitis (AAV) patients. Because imatinib, a selective inhibitor of the ABL, ARG, PDGFR and c‐KIT tyrosine kinases, inhibits T cell activation, this study was conducted to evaluate the potential use of imatinib for the treatment AAV patients refractory to conventional therapy. In particular, we investigated the inhibition of T cell activation by this drug and its efficacy on activated T cells from anti‐neutrophil cytoplasmic autoantibodies (ANCA)‐associated systemic vasculitides (AASV) patients. T cell stimulation has been induced by anti‐CD3/anti‐CD28 antibodies or by phorbol myristate acetate (PMA)/ionomycin. T cell proliferation was analysed by tritiumthymidine incorporation. Cell cycle progression was determined by propidium iodide staining using fluorescence activated cell sorter (FACS) analysis and by RNAse protection assay (RPA). Cytokine levels were assessed by enzyme‐linked immunosorbent assay. T cell proliferation was inhibited significantly by imatinib, due most probably to cell cycle arrest in the G1‐phase. This was paralleled by inhibition in the expression of cyclin‐dependent kinases 1 and 2 mRNA. The expression of CD25 in naive and memory T cells was decreased significantly by imatinib in activated T cells. Similarly, conversion from naive to memory T cells after T cell activation was impaired by imatinib. Imatinib did not influence interleukin‐2 and tumour necrosis factor‐α production but increased interferon‐γ production. These observed effects of imatinib were similar in T cells from AASV patients and from healthy individuals. Imatinib might be an alternative therapeutical option for AASV patients refractory to conventional therapy.

The role of endothelial progenitor cells in sepsis

ZusammenfassungDas Ausmaß der mikrovaskulären Schädigung spielt eine zentrale Rolle in der Pathogenese der Sepsis. Es wird durch endotheliale Dysfunktionen wie Schwellung, Deformierung und Apoptose mit teilweisem Ablösen der Endothelzellen von der Basalmembran bestimmt, die dann als zirkulierende Endothelzellen und endotheliale Mikropartikel vermehrt im Blut von Sepsispatienten gefunden wurden. Die Reparatur dieses geschädigten Endothels, d.xa0h. die Wiederherstellung einer endothelialen Homöostase, könnte somit eine Schlüsselrolle in der Sepsistherapie spielen. Es gibt heute Hinweise, dass endotheliale Vorläuferzellen, die durch eine Reihe stimulierender Mediatoren vermehrt aus dem Knochenmark freigesetzt werden, eine Reendothelialisierung bzw. über parakrine Effekte eine gesteigerte Proliferation bereits vorhandener Zellen bewirken können. Derartige Reparatureffekte konnten unter verschiedenen Bedingungen endothelialer Schädigung, insbesondere akute kardiovaskuläre Ereignisse, Dialyse, aber auch beim akuten Lungenversagen bereits nachgewiesen werden. Erste Untersuchungen konnten jetzt zeigen, dass auch im Blut von Sepsispatienten neben abgelösten Endothelzellen vermehrt endotheliale Vorläuferzellen zirkulieren, deren Konzentration umgekehrt proportional zu Schwere und Mortalität bei Sepsis ist und mit der Konzentration der Zytokine, die für die Freisetzung endothelialer Progenitorzellen (EPC) aus dem Knochenmark verantwortlich sind, korrelieren. Diese Erkenntnisse unterstützen die Hypothese, dass auch bei einer Sepsis endotheliale Reparaturmechanismen in Form der mediatorinduzierten vermehrten Freisetzung endothelialer Vorläuferzellen aus dem Knochenmark initiiert werden. Somit könnten Messungen der cEPC-Konzentrationen als diagnostischer oder prognostischer Parameter der Schwere des Gefäßschadens und der Sepsis dienen, und die Erhöhung der EPC-Konzentration eine mögliche Therapieoption sein.AbstractIn sepsis and septic shock a series of immunological events are initiated that alter endothelial function in the macrocirculation and microcirculation. Endothelial swelling, deformation and apoptosis with detachment from the vasculature occur and endothelial cells (EC) appear in the circulation. Simultaneous to these pathological processes, reconstitution of the endothelial layer is initiated which can occur via migration and proliferation of surrounding mature ECs. However, terminally differentiated ECs have a low proliferative potential, hence their capacity to substitute damaged endothelium is limited. Therefore, adequate vascular repair requires additional support. Many studies have now convincingly demonstrated that vascular maintenance, repair, angiogenesis and neovascularization are partly mediated by recruitment of endothelial progenitor cells (EPCs) from the basal membrane. However, it seems that EPCs play a pivotal role not only in re-endothelialization after vascular damage, but also after severe inflammation. Recently, evidence was found that EPCs are increasingly mobilized during sepsis and that this mobilization is associated with clinical outcome. In septic patients the number of EPCs was significantly higher than in controls and was correlated with survival and the concentration of cytokines. In summary EPCs may exert an important function as an endogenous repair mechanism to maintain the integrity of the endothelial layer by replacing denuded parts of the microcirculation or by stimulation of EC proliferation. Therefore, EPC enumeration seems to be a valuable prognostic and diagnostic marker for the outcome in these patients and the induction of enhanced EPC mobilization a therapeutic option.In sepsis and septic shock a series of immunological events are initiated that alter endothelial function in the macrocirculation and microcirculation. Endothelial swelling, deformation and apoptosis with detachment from the vasculature occur and endothelial cells (EC) appear in the circulation. Simultaneous to these pathological processes, reconstitution of the endothelial layer is initiated which can occur via migration and proliferation of surrounding mature ECs. However, terminally differentiated ECs have a low proliferative potential, hence their capacity to substitute damaged endothelium is limited. Therefore, adequate vascular repair requires additional support. Many studies have now convincingly demonstrated that vascular maintenance, repair, angiogenesis and neovascularization are partly mediated by recruitment of endothelial progenitor cells (EPCs) from the basal membrane. However, it seems that EPCs play a pivotal role not only in re-endothelialization after vascular damage, but also after severe inflammation. Recently, evidence was found that EPCs are increasingly mobilized during sepsis and that this mobilization is associated with clinical outcome. In septic patients the number of EPCs was significantly higher than in controls and was correlated with survival and the concentration of cytokines. In summary EPCs may exert an important function as an endogenous repair mechanism to maintain the integrity of the endothelial layer by replacing denuded parts of the microcirculation or by stimulation of EC proliferation. Therefore, EPC enumeration seems to be a valuable prognostic and diagnostic marker for the outcome in these patients and the induction of enhanced EPC mobilization a therapeutic option.

Die Rolle endothelialer Vorläuferzellen in der Sepsis

ZusammenfassungDas Ausmaß der mikrovaskulären Schädigung spielt eine zentrale Rolle in der Pathogenese der Sepsis. Es wird durch endotheliale Dysfunktionen wie Schwellung, Deformierung und Apoptose mit teilweisem Ablösen der Endothelzellen von der Basalmembran bestimmt, die dann als zirkulierende Endothelzellen und endotheliale Mikropartikel vermehrt im Blut von Sepsispatienten gefunden wurden. Die Reparatur dieses geschädigten Endothels, d.xa0h. die Wiederherstellung einer endothelialen Homöostase, könnte somit eine Schlüsselrolle in der Sepsistherapie spielen. Es gibt heute Hinweise, dass endotheliale Vorläuferzellen, die durch eine Reihe stimulierender Mediatoren vermehrt aus dem Knochenmark freigesetzt werden, eine Reendothelialisierung bzw. über parakrine Effekte eine gesteigerte Proliferation bereits vorhandener Zellen bewirken können. Derartige Reparatureffekte konnten unter verschiedenen Bedingungen endothelialer Schädigung, insbesondere akute kardiovaskuläre Ereignisse, Dialyse, aber auch beim akuten Lungenversagen bereits nachgewiesen werden. Erste Untersuchungen konnten jetzt zeigen, dass auch im Blut von Sepsispatienten neben abgelösten Endothelzellen vermehrt endotheliale Vorläuferzellen zirkulieren, deren Konzentration umgekehrt proportional zu Schwere und Mortalität bei Sepsis ist und mit der Konzentration der Zytokine, die für die Freisetzung endothelialer Progenitorzellen (EPC) aus dem Knochenmark verantwortlich sind, korrelieren. Diese Erkenntnisse unterstützen die Hypothese, dass auch bei einer Sepsis endotheliale Reparaturmechanismen in Form der mediatorinduzierten vermehrten Freisetzung endothelialer Vorläuferzellen aus dem Knochenmark initiiert werden. Somit könnten Messungen der cEPC-Konzentrationen als diagnostischer oder prognostischer Parameter der Schwere des Gefäßschadens und der Sepsis dienen, und die Erhöhung der EPC-Konzentration eine mögliche Therapieoption sein.AbstractIn sepsis and septic shock a series of immunological events are initiated that alter endothelial function in the macrocirculation and microcirculation. Endothelial swelling, deformation and apoptosis with detachment from the vasculature occur and endothelial cells (EC) appear in the circulation. Simultaneous to these pathological processes, reconstitution of the endothelial layer is initiated which can occur via migration and proliferation of surrounding mature ECs. However, terminally differentiated ECs have a low proliferative potential, hence their capacity to substitute damaged endothelium is limited. Therefore, adequate vascular repair requires additional support. Many studies have now convincingly demonstrated that vascular maintenance, repair, angiogenesis and neovascularization are partly mediated by recruitment of endothelial progenitor cells (EPCs) from the basal membrane. However, it seems that EPCs play a pivotal role not only in re-endothelialization after vascular damage, but also after severe inflammation. Recently, evidence was found that EPCs are increasingly mobilized during sepsis and that this mobilization is associated with clinical outcome. In septic patients the number of EPCs was significantly higher than in controls and was correlated with survival and the concentration of cytokines. In summary EPCs may exert an important function as an endogenous repair mechanism to maintain the integrity of the endothelial layer by replacing denuded parts of the microcirculation or by stimulation of EC proliferation. Therefore, EPC enumeration seems to be a valuable prognostic and diagnostic marker for the outcome in these patients and the induction of enhanced EPC mobilization a therapeutic option.In sepsis and septic shock a series of immunological events are initiated that alter endothelial function in the macrocirculation and microcirculation. Endothelial swelling, deformation and apoptosis with detachment from the vasculature occur and endothelial cells (EC) appear in the circulation. Simultaneous to these pathological processes, reconstitution of the endothelial layer is initiated which can occur via migration and proliferation of surrounding mature ECs. However, terminally differentiated ECs have a low proliferative potential, hence their capacity to substitute damaged endothelium is limited. Therefore, adequate vascular repair requires additional support. Many studies have now convincingly demonstrated that vascular maintenance, repair, angiogenesis and neovascularization are partly mediated by recruitment of endothelial progenitor cells (EPCs) from the basal membrane. However, it seems that EPCs play a pivotal role not only in re-endothelialization after vascular damage, but also after severe inflammation. Recently, evidence was found that EPCs are increasingly mobilized during sepsis and that this mobilization is associated with clinical outcome. In septic patients the number of EPCs was significantly higher than in controls and was correlated with survival and the concentration of cytokines. In summary EPCs may exert an important function as an endogenous repair mechanism to maintain the integrity of the endothelial layer by replacing denuded parts of the microcirculation or by stimulation of EC proliferation. Therefore, EPC enumeration seems to be a valuable prognostic and diagnostic marker for the outcome in these patients and the induction of enhanced EPC mobilization a therapeutic option.

Effekte von Dopamin auf die zelluläre und humorale Immunantwort von Patienten mit Sepsis

ZusammenfassungZahlreiche In-vitro- und In-vivo-Studien belegen, dass Dopamin neben seinen hämodynamischen Effekten eine Reihe immunmodulatorischer Wirkungen induziert. Dopamin reduziert die Synthese proinflammatorischer und induziert die Synthese antiinflammatorischer Mediatoren. Dopamin hemmt die Synthese neurohypophysärer Hormone und hemmt die Zellproliferation sowie die Thrombozytenaggregation. Es reduziert die Phagozytoseaktivität neutrophiler Granulozyten und induziert Apoptose. Bei hohen Dopaminserumkonzentrationen, wie sie bei einer Sepsis durch vermehrte endogene Synthese, zusätzliche exogene Applikation und verringerte Clearance erreicht werden, könnten diese Effekte zu relevanten Veränderungen pathophysiologischer Abläufe führen. Um die Bedeutung von Dopamin für die zelluläre und humorale Immunantwort von Patienten mit Sepsis hervorzuheben, sind in dieser Übersicht die speziellen Wirkungen von Dopamin zusammengefasst und die zugrunde liegenden Mechanismen dargestellt.AbstractIn vitro and in vivo studies have demonstrated that apart from its hemodynamic action dopamine can modulate immune responses. Dopamine reduces the synthesis of proinflammatory and induces the synthesis of anti-inflammatory mediators. Dopamine inhibits neurohormone synthesis, lymphocyte proliferation and platelet aggregation. It reduces the phagocytic activity of neutrophils and induces apoptosis. Particularly with regard to sepsis, where high serum dopamine levels are reached by enhanced endogeneous production, exogeneous application and impaired clearance, this immunomodulation may have a clinical impact. This review summarizes dopamine-mediated immunomodulating effects to advance the knowledge regarding dopamine as an immune regulator under septic conditions.In vitro and in vivo studies have demonstrated that apart from its hemodynamic action dopamine can modulate immune responses. Dopamine reduces the synthesis of proinflammatory and induces the synthesis of anti-inflammatory mediators. Dopamine inhibits neurohormone synthesis, lymphocyte proliferation and platelet aggregation. It reduces the phagocytic activity of neutrophils and induces apoptosis. Particularly with regard to sepsis, where high serum dopamine levels are reached by enhanced endogenous production, exogenous application and impaired clearance, this immunomodulation may have a clinical impact. This review summarizes dopamine-mediated immunomodulating effects to advance the knowledge regarding dopamine as an immune regulator under septic conditions.

The role of T lymphocytes in ANCA associated vasculitis: neglected or revisited?

Antineutrophil cytoplasmic antibodies (ANCA) are pathogenic--Oh yes they are! is the title of a recent review [Falk et al. 2002], discussing the current evidence on the pathogenic role of ANCA in vasculitis. But what about T lymphocytes? Do these cells also contribute to disease manifestation and if so to what extend? T-cells most likely play a role in delivering proper signals to autoreactive B cells for the production of ANCA, but, in the efferent arm of the immune response the involvement of T cells is less obvious and controversially discussed. Numerous studies provide evidence that peripheral T-cell phenotypes are dramatically changed in ANCA associated vasculitis (AAV) patients. How these changes relate to disease manifestation is still a matter of discussion. In an attempt to provide a better understanding of how T cells might play a role in AAV, the present paper will review recent data presented at the 12th international vasculitis and ANCA workshop.

Graft-Infiltrating Cells Can Recognize Tissue-Specific Antigens on Proximal Tubular Epthelial Cells during Acute Renal Allograft Rejection

Zusammenfassung Die akute Abstoßung nach einer Nieren-Allotransplantation ist durch eine Infiltration mononukleärer Zellen in das Interstitium gekennzeichnet. Diese Immunreaktion scheint gegen Nieren-spezifische Antigene gerichtet zu sein. In unserer Studie analysierten wir die gewebespezifische Erkennung von proximalen tubulären epithelialen Zellen (PTEC) durch Gewebe-infiltrierende Zellen (GIC). Von 25 T-Zellinien zeigten 5 keine Zytotoxizität gegen PTEC-Zellen des Spenders. Drei Linien waren zytotoxisch gegen PTEC-Zellen und nicht gegen PHA-stimulierte Splenozyten. Hierbei handelte es sich um gewebespezifische GIC. Bei der Klonierung einer gewebespezifischen Zellinie wurden 18 zytotoxische T-ZellKlone etabliert, von denen alle Klone CD8+ und TCR a/b+ positiv waren. Alle Klone lysierten HLA-A31-exprimierende PTEC, jedoch zeigten drei Klone nicht diese Eigenschaft. Die Ergebnisse verdeutlichen, daß hier ein Gewebe-assoziierter Polymorphismus vorliegt und menschliche nierenspezifische Antigene durch GIC in vitro erkannt werden können. Gewebeinfiltrierende Zellen könnten daher eine große Rolle bei der Zerstörung der Tubuli während einer akuten Abstoßungsreaktion spielen.