Novel Insights into Oxidative Stress and Antioxidant Enzymes in Acute Antibody-Mediated Rejection of Renal Allografts.

Antibody mediated rejection (AMR) is a major challenge in kidney transplantation and adversely affects allograft survival. Oxidative stress (OS) is implicated in AMR pathogenesis by triggering inflammation, apoptosis and fibrosis in the graft tissue. However, the status of OS and antioxidant defense in AMR patients remains unclear. We aimed to evaluate the levels of OS markers and antioxidant enzymes in AMR patients.  Methods. We conducted a case-control study involving 22 biopsy-proven AMR patients (test group) and 14 kidney recipients with stable graft function (control group). Serum total oxidant status (TOS), total antioxidant capacity (TAC), total thiol groups, nitric oxide (NO), 8-isoprostane (8-IP) were determined and activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) were measured by spectrophotometric methods. Data analysis showed significant increases in TOS, TAC and 8-IP levels together with marked reductions in NO and total thiol groups in AMR patients. CAT and GPx activities did not differ between groups, however SOD activity was significantly lower in AMR patients. Our study showed increased OS and impaired antioxidant defense in AMR patients. NO level may serve as a potential biomarker of OS severity and immune response in AMR. Further studies are required to elucidate the mechanisms and consequences of OS in AMR and to explore the therapeutic potential of antioxidants.