Abstract

Background
Cilastatin (CL) is an inhibitor of dehydropeptidase-I, which is safely used in clinical practice to prevent nephrotoxicity of antibiotics. Tacrolimus (TAC) is the most important immunosuppressant in renal transplantation, but it causes considerable nephrotoxicity. We evaluated the protective effects of CL against chronic TAC-induced nephropathy.

Methods
Chronic nephropathy was induced by administering TAC (1.5 mg/kg/ day, subcutaneous injection) to rats on a low-salt diet for 4 weeks. CL (75 or 150 mg/kg/day, intraperitoneal injection) was concomitantly treated with TAC. Human proximal tubular cells were exposed to TAC (50 μg/mL) with or without CL (250 μg/mL). We investigated the effects of CL on TAC-induced injury in terms of renal function, tubulointerstitial fibrosis, and inflammation. The effects of CL on oxidative stress and apoptosis were evaluated in both in vivo and in vitro models of TAC nephrotoxicity.

Results
CL treatment improved TAC-induced renal dysfunction and decreased renal interstitial fibrosis (reduced expression of e-cadherin and TGFβ-1) and interstitial inflammation (decreased infiltration of ED-1-positive and osteopontin-positive cells). Compared to TAC treatment alone, CL co-treatment reduced oxidative stress (serum 8-OHdG level and immunoreactivity of 8-OHdG and 4-HHE in renal tissue) and increased renal expression of anti-oxidant enzyme, manganese superoxide dismutase. CL treatment decreased apoptotic cell death (decreased TUNEL-positive cells and reduced expression of active caspase-3) in TAC-treated kidney. In vitro CL treatment prevented tubular cell death from TAC treatment and decreased number of annexin V-positive cells were observed in cilastatin-cotreated cells.

Conclusion
CL has protective effects against chronic TAC-induced nephrotoxicity owing to its anti-oxidative and anti-apoptotic properties.

Keywords
Cilastatin Tacrolimus Nephrotoxicity