Protective Effect of Paricalcitol on Cyclosporine-Induced Renal Injury in Rats

We evaluated the protective effect of paricalcitol on cyclosporine (CsA)–induced renal injury using an experimental model of chronic CsA nephropathy. Paricalcitol (50 and 200 ng/kg/d) was concomitantly administered with CsA (15 mg/kg/d) for 28 days in rats. We assessed the effects of paricalcitol by measuring degree of the tubulointerstitial fibrosis (TIF) and inflammation, a profibrotic cytokine (βig-h3), a proapoptotic gene (caspase-3), apoptotic cell death, and oxidative stress. The CsA-treated rats showed increased TIF and inflammatory cell infiltration, but paricalcitol treatment (200 ng/kg) significantly decreased those compared with the CsA-alone group. The expression of βig-h3, a biologic marker of transforming growth factor β1, which was increased in the CsA group, also decreased with paricalcitol treatment. The increased rates of excretion of urinary 8-hydroxy-2′-deoxyguanosine (8-OHdG) and expression of tissue 8-OHdG produced by CsA treatment were significantly attenuated by paricalcitol treatment. The increased expression of caspase-3 and number of TUNEL-positive cells in the CsA group were decreased with concomitant paricalcitol treatment. The effect of paricalcitol was more evident high among the rather than low-dose cohort. In conclusion, paricalcitol showed antiinflammatory and antifibrotic effects. This finding may provide a rationale for use of paricalcitol in CsA-induced renal injury.