Pirfenidone Attenuates Cardiac Fibrosis in a Mouse Model of TAC-Induced Left Ventricular Remodeling by Suppressing NLRP3 Inflammasome Formation

OBJECTIVES: Left ventricular remodeling is a frequent complication of hypertension with no therapeutic treatment available for the subsequent onset of myocardial fibrosis. Pirfenidone is an antifibrotic small-molecular-size drug with anti-inflammatory properties that is used as a treatment for fibrotic diseases, but its effects on hypertension-induced myocardial fibrosis are unknown. Therefore, we tested whether pirfenidone could ameliorate hypertension-induced left ventricular remodeling and whether hypertension-induced NLRP3 (Nod-like receptor pyrin domain containing 3), a critical protein in NLRP3 inflammasome formation, is involved in the therapeutic mechanism. METHODS: A TAC-induced mouse model of hypertension and left ventricular hypertrophy was treated with pirfenidone, and survival, collagen deposition by histopathologic examination, heart function by echocardiography, concentrations of fibrosis-related inflammatory cytokines TGF-β1, IL-1β in heart homogenate and in vitro cell cultures by ELISA, levels of ROS and inflammatory cells by flow cytometry, and levels of NLRP3 by Western blotting and immunohistochemistry were measured. RESULTS: Pirfenidone increased the survival rate and attenuated myocardial fibrosis and inflammatory mediators in the TAC-induced hypertension-complicated left ventricular remodeling mouse model. The inhibition of NLRP3 expression by pirfenidone attenuated the expression of IL-1β and IL-1β-induced inflammatory and profibrotic responses. CONCLUSIONS: Pirfenidone may be useful in the treatment of hypertension-induced myocardial fibrosis by inhibiting NLRP3-induced inflammation and fibrosis.