Up-regulation of cyclooxygenase-2 during acute human renal allograft rejection

Abstract

Cyclooxygenases-1 and -2 (COX-1 and COX-2) are important in renal physiology and in many abnormal states. However, there is poor information about them during renal allograft rejection. The purpose of this study was to analyze cyclooxygenases expression in renal tissue allograft during acute rejection. COX-1 and COX-2 transcripts and proteins were analyzed by semi-quantitative RT-PCR and immunohistochemistry in samples from human renal allografts obtained from nephrectomy because of irreversible acute rejection. In samples with acute rejection, we detected higher expression of COX-2 mRNA in comparison with COX-1 (p < 0.001) being COX-2 expression not different from COX-1 in samples from renal allografts without acute rejection. COX-1 and COX-2 localization was in accordance with data described in literature, however COX-2 protein was higher in interstitial cells in the group with rejection than in the group without rejection (p = 0.04). In addition, in samples with acute rejection COX-2 immunoreactivity was more prominent in podocytes (p < 0.001), in proximal tubules (p < 0.001), in collecting duct cells (p = 0.003) and in interstitial cells (p < 0.001) when compared with COX-1. Our data show that there is an increased production of COX-2 during acute renal rejection.