Contribution of CD4+ T cells to the early mechanisms of ischemia- reperfusion injury in a mouse model of acute renal failure.

Renal ischemia-reperfusion (IR) injury is the major cause of acute renal failure in native and transplanted kidneys. Mononuclear leukocytes have been reported in renal tissue as part of the innate and adaptive responses triggered by IR. We investigated the participation of CD4+ T lymphocytes in the pathogenesis of renal IR injury. Male mice (C57BL/6, 8 to 12 weeks old) were submitted to 45 min of ischemia by renal pedicle clamping followed by reperfusion. We evaluated the role of CD4+ T cells using a monoclonal depleting antibody against CD4 (GK1.5, 50 micro, ip), and class II-major histocompatibility complex molecule knockout mice. Both CD4-depleted groups showed a marked improvement in renal function compared to the ischemic group, despite the fact that GK1.5 mAb treatment promoted a profound CD4 depletion (to less than 5% compared to normal controls) only within the first 24 h after IR. CD4-depleted groups presented a significant improvement in 5-day survival (84 vs 80 vs 39%; antibody treated, knockout mice and non-depleted groups, respectively) and also a significant reduction in the tubular necrosis area with an early tubular regeneration pattern. The peak of CD4-positive cell infiltration occurred on day 2, coinciding with the high expression of betaC mRNA and increased urea levels. CD4 depletion did not alter the CD11b infiltrate or the IFN-gamma and granzyme-B mRNA expression in renal tissue. These data indicate that a CD4+ subset of T lymphocytes may be implicated as key mediators of very early inflammatory responses after renal IR injury and that targeting CD4+ T lymphocytes may yield novel therapies.

Contribution of CD4+ T cells to the early mechanisms of ischemia- reperfusion injury in a mouse model of acute renal failure

Renal ischemia-reperfusion (IR) injury is the major cause of acute renal failure in native and transplanted kidneys. Mononuclear leukocytes have been reported in renal tissue as part of the innate and adaptive responses triggered by IR. We investigated the participation of CD4+ T lymphocytes in the pathogenesis of renal IR injury. Male mice (C57BL/6, 8 to 12 weeks old) were submitted to 45 min of ischemia by renal pedicle clamping followed by reperfusion. We evaluated the role of CD4+ T cells using a monoclonal depleting antibody against CD4 (GK1.5, 50 æ, ip), and class II-major histocompatibility complex molecule knockout mice. Both CD4-depleted groups showed a marked improvement in renal function compared to the ischemic group, despite the fact that GK1.5 mAb treatment promoted a profound CD4 depletion (to less than 5 percent compared to normal controls) only within the first 24 h after IR. CD4-depleted groups presented a significant improvement in 5-day survival (84 vs 80 vs 39 percent; antibody treated, knockout mice and non-depleted groups, respectively) and also a significant reduction in the tubular necrosis area with an early tubular regeneration pattern. The peak of CD4-positive cell infiltration occurred on day 2, coinciding with the high expression of ßC mRNA and increased urea levels. CD4 depletion did not alter the CD11b infiltrate or the IFN-g and granzyme-B mRNA expression in renal tissue. These data indicate that a CD4+ subset of T lymphocytes may be implicated as key mediators of very early inflammatory responses after renal IR injury and that targeting CD4+ T lymphocytes may yield novel therapies.

Interleukin-2 gene polymorphism is associated with renal but not cardiac transplant outcome.

It was recently shown that IL-2 gene single nucleotide polymorphism (SNP) at position -330 (G-->T) is related to in vitro cytokine production levels, with the T/T and T/G genotypes being associated with low production and the G/G genotype associated with high production. The objective of this study was to investigate a possible influence of this polymorphism on renal and cardiac allograft outcomes. IL-2 SNP G-T (-330) was determined by PCR-RFLP in 67 recipients of heart allografts and in 63 recipients of renal grafts from HLA-haplo-identical, related donors. A higher frequency of the T/T genotype was observed in renal transplant patients who experienced at least one acute rejection episode during the first 3 months after transplantation than in those without rejection during this period (80% vs 49%, respectively, P <.05). Accordingly, the same genotype tended to be more frequent in renal recipients with a 6-month serum creatinine level above 1.5 mg/dL (median value for the whole group of kidney recipients) than in patients with lower creatinine levels (79% vs 45%, P <.08). Regarding cardiac transplant recipients, no associations were observed concerning acute rejection or graft survival. The finding of the association of T/T but not T/G genotype with acute kidney rejection was unexpected considering that both genotypes were shown to be associated with equal (low) IL-2 in vitro production. Further studies are necessary not only to dissect the nature of IL-2 T/T genotype association with kidney rejection, but also to explain why this genotype does not apparently influence cardiac allograft outcome.

Otimizaçäo do uso da ciclosporina em transplante renal / Optimization of the use of cyclosporin in renal transplantation

Avaliamos retrospectivamente estratégias empregadas na otimizaçäo do uso clínico da ciclosporina (CSA) em transplante renal. Baseado na incidência de rejeiçäo aguda nos primeiros 15 dias do transplante, a administraçäo oral da CSA foi superior à infusäo endovenosa constante, apesar dos relatos divergentes na literatura. A falta de monitorizaçäo do nível sanguíneo da CSA e o uso de doses diferentes de esteróides podem ser responsáveis pelo encontro de tais resultados. A minitorizaçäo do nível sanguíneo de CSA foi útil no diagnóstico diferencial de rejeiçäo aguda (RA) e nefrotoxicidade por CSA (NTX), definindo faixas de concentraçäo sangüínea ideais onde o risco de desenvolvimento de algum tipo de disfunçäo foi menor. Esta "faixa terapêutica" ficou entre 200 e 400ng/mL, quando foi utilizado radioimunoensaio tricidado com anticorpo policlonal (PC-CSA-H3), e entre 100 e 250ng/mL, utilizando RIA com anticorpo monoclonal específico (ME-CSA-H3), observando-se uma correlaçäo com um r=0,82 entre os dois métodos em 122 determinaçöes simultâneas. Alteraçöes histológicas encontradas nas biópsias renais de pacientes com RA näo foram diferentes daquelas obtidas de pacientes com NTX, antes ou após 90 dias de transplante. Concluímos que, por näo dispormos, no momento, de um único método com elevada sensibilidade, especificidade e valor preditivo, a monitorizaçäo do nível sanguíneo de CSA associada à biópsia renal é a melhor forma de reduzir a incidência de disfunçäo do enxerto, assegurando uma maior sobrevida, a longo prazo

[Optimization of the use of cyclosporin in renal transplantation]. / Otimização do uso da ciclosporina em transplante renal.

Strategies to optimize the use of cyclosporin A (CSA) in renal transplant were analysed retrospectively. Based on the incidence of acute rejection during the first 15 days of transplant, oral dosing achieved adequate immunosuppression earlier than constant intravenous infusion of CSA. The lack of CSA blood monitoring and the use of different steroid doses in this period could be responsible for these conflicting results. The differential diagnosis between acute rejection (AR) and CSA nephrotoxicity (NX) during the first year of transplant was made based on clinical findings, CSA levels and histological evaluation. Therapeutic CSA concentration range between 200 and 400 ng/mL, using radioimmunoassay with polyclonal antibodies, and between 100 and 250 ng/mL, using specific monoclonal antibodies, were found. A correlation of r = 0.82 between these two methods were obtained in 122 simultaneous dosages. Histological abnormalities found in biopsies from patients with AR were not different from those obtained from patients with NX, before and after 90 days of transplant. The conclusion was drawn that the therapeutic CSA monitoring associated with histological evaluation can reduce the incidence of renal dysfunction and promote a long-term and stable graft survival.