Renal transplantation is often confronted with ischemia reperfusion (I/R) injury that accounts for a delayed recovery of the graft. This surgically and biologically induced injury often results in activation of the complement system. The vaccinia virus complement control protein (VCP) down-regulates both the classical and alternative complement pathways by preventing the formation of C3b, a component where both pathways converge. The aim of the study was to investigate the effect of VCP on renal I/R injury. Long Evans rats were subjected to laparotomy, mobilization of the right kidney in unilateral ischemia, and both kidneys in bilateral ischemia. The renal arteries were clamped for 60 min followed by 24 h reperfusion time. The animals were randomly allocated to receive recombinant VCP (rVCP), natural VCP, and humanized recombinant VCP (hrVCP) combination, vehicle (PBS), or sham group. Blood samples were collected for biochemical studies, and the kidneys were removed for histopathologic and immunohistochemical studies. The biochemical studies in the bilateral ischemia showed that the PBS group displayed 1.5-fold and 5-fold increases in the urea and creatinine concentrations, respectively, compared with the VCP/hrVCP groups. In both models, the histopathologic study revealed focal necrosis of the tubular epithelial cells in the rVCP or VCP/hrVCP treated animals compared with the diffuse and markedly elevated field scores in the PBS controls. The immunohistochemical study showed significant C3 deposition in the renal tubules of the PBS controls compared with the rVCP or VCP/hrVCP groups, suggesting that rVCP, VCP/hrVCP reduced I/R injury by inhibiting the biosynthesis of C3.
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