Renoprotective mechanisms of pirfenidone in hypertension-induced renal injury: through anti-fibrotic and anti-oxidative stress pathways.

Pirfenidone (PFD) is a novel anti-fibrotic agent that targets TGFβ. However, the mechanisms underlying its renoprotective properties in hypertension-induced renal injury are poorly understood. We investigated the renoprotective properties of PFD and clarified its renoprotective mechanisms in a rat hypertension-induced renal injury model. Dahl salt-sensitive rats were fed a high-salt diet with or without 1% PFD for 6 weeks. During the administration period, we examined the effects of PFD on blood pressure and renal function. After the administration, the protein levels of renal TGFβ, Smad2/3, TNFα, MMP9, TIMP1, and catalase were examined. In addition, total serum antioxidant activity was measured. Compared to untreated rats, PFD treatment significantly attenuated blood pressure and proteinuria. Histological study showed that PFD treatment improved renal fibrosis. PFD may exert its anti-fibrotic effects via the downregulation of TGFβ-Smad2/3 signaling, improvement of MMP9/TIMP1 balance, and suppression of fibroblast proliferation. PFD treatment also increased catalase expression and total serum antioxidant activity. In contrast, PFD treatment did not affect the expression of TNFα protein, macrophage or T-cell infiltration, or plasma interleukin 1β levels. PFD prevents renal injury via its anti-fibrotic and anti-oxidative stress mechanisms. Clarifying the renoprotective mechanisms of PFD will help improve treatment for chronic renal diseases.