Abstract

Idiopathic pulmonary fibrosis (IPF) is a lethal lung disease, and its 5-year mortality rate is even higher than the mortality rate of some cancers. Fibrosis can cause irreversible damage to lung structure and function. Treatment options for IPF remain limited, and there is an urgent need to develop effective therapeutic drugs. Protease activated receptor-1 (PAR-1) is a G-protein-coupled receptor and is considered a potential target for the treatment of fibrotic diseases. Vorapaxar is a clinically approved PAR-1 antagonist for cardiovascular protection. The purpose of this study was to explore the potential effect and mechanism of Vorapaxar on pulmonary fibrosis in vivo and in vitro . In the experimental animal model, Vorapaxar can effectively alleviate bleomycin (BLM)-induced pulmonary fibrosis. Treatment with 2.5, 5 or 10 mg/kg Vorapaxar once a day reduced the degree of fibrosis in a dose-dependent manner. The expression of fibronectin , collagen and α smooth muscle actin decreased significantly at the messenger RNA (mRNA) and protein levels in treated mice. In vitro , our results showed that Vorapaxar could inhibit the activation of fibroblasts induced by thrombin in a dose-dependent manner. In terms of mechanism, Vorapaxar inhibits the signal transduction of JAK2/STAT1/3 by inhibiting the activation of protease activated receptor 1, which reduces the expression of HSP90β and the interaction between HSP90β and transforming growth factor-β (TGFβ) receptor II and inhibits the TGFβ/Smad signaling pathway. In conclusion, Vorapaxar inhibits the activation of pulmonary fibroblasts induced by thrombin by targeting protease activated receptor 1 and alleviates BLM-induced pulmonary fibrosis in mice.