Effect of mycophenolate mofetil on CD26 expression in the kidneys of diabetic rats

Objective To investigate the expression of CD26 (dipeptidyl peptidase 4) in the kidney tissues of diabetic rats and the effects of mycophenolate mofetil (MMF) on the renal CD26 expression. Methods Wistar rats were randomly divided into three groups: normal control group (NC group, n=7), diabetic model group (DM group, n=7) and MMF-treated group (MMF group, n=7). Wistar rats were fed with high-sucrose-high-fat diet and injected with streptozotocin into abdominal cavity to induce diabetes. Sixteen weeks later, blood glucose (BG), blood urea nitrogen (BUN), serum creatinine (Scr), renal hypertrophy index (kidney weight/body weight) and 24 hour urinary protein (24Upro) were measured. The number of CD3+/CD4+ T cells in renal tissues were measured through flow cytometry. The expression of CD26 in kidney was examined by using Western blotting and immunohistochemistry. Results Compared with NC group, BG, BUN, Scr, kidney weight/body weight, 24Upro were significantly increased in DM group (P﹤0.05). Except BG and kidney weight/body weight, the above-mentioned parameters were lower in MMF group compared with that in DM group (P﹤0.05). Intrarenal CD3+/CD4+ T cells were significantly up-regulated in DM group compared with that in NC group (P﹤0.01). CD26 in renal tissue was mainly expressed in T lymphocytes of renal interstitium. CD26 expression in DM group was significantly higher than that in NC group, and also higher than that in MMF group (P﹤0.05). In DM group, CD26+ T lymphocytes infiltration of renal interstitium was positively correlated with 24Upro (r2=0.770, P﹤0.05). Conclusions CD26 is related with diabetic nephropathy. MMF maybe inhibit T lymphocytes infiltration to reduce the expression of CD26 in renal interstitium, thus protecting the kidney function.