[Mechanism of Xueshuantong Injection on bleomycin-induced pulmonary fibrosis in rats based on coagulation cascade pathway].

This study aims to investigate the mechanism of Xueshuantong Injection(XST) on pulmonary fibrosis induced by bleomycin(BLM) in rats based on the coagulation cascade pathway. Sixty SD rats were randomly divided into sham surgery group,model group, pirfenidone(PFD, 50 mg·kg~(-1)) group, and 27, 54, and 81 mg·kg~(-1) XST groups. The rat model of pulmonary fibrosis was established by intratracheal injection of BLM(5 mg·kg~(-1)). After 24 hours, the administration groups were given corresponding drugs, while the sham surgery group and model group were given equal volumes of saline. On the 28th day, samples were collected,and the imaging and collagen fiber changes in the lungs of rats were observed. Immunofluorescence(IF) method was used to detect the expression level of alpha-smooth muscle actin(α-SMA), collagen Ⅰ(Col-Ⅰ), E-cadherin(E-cad), and vimentin(Vim). Western blot was used to determine the protein expression of α-SMA, Col-Ⅰ, Vim, and E-cad. Enzyme-linked immunosorbent assay(ELISA)was used to detect the levels of prothrombin fragment(F1 + 2), thrombin-antithrombin complex(TAT), soluble fibrin monomer complex(SFMC), and rat fibrinogen degradation products(FDP) in rat lung tissue. Finally, the mRNA and protein levels of protease activated receptor 1(PAR-1) were detected by RT-qPCR, western blot, and IF. Compared with the model group, the scanning of the lungs of rats receiving XST treatment also exhibited patchy and non-homogeneous shadows, but these shadows were less dense than those in the model group. At the same time, there was a significant decrease in Col-Ⅰ fibers in the lungs of rats, and XST could inhibit epithelial-mesenchymal transition(EMT) and downregulate α-SMA and Col-Ⅰ protein expression. In the aspect of the coagulation system, administration of 81 mg·kg~(-1) XST significantly reduced the levels of SFMC and FDP. Meanwhile, 81 mg·kg~(-1) XST significantly downregulated the mRNA and protein levels of PAR-1. XST has an anti-pulmonary fibrosis effect in rats, and its mechanism may be related to the downregulation of PAR-1 to rebalance the coagulation cascade pathway.