Hirudin Inhibits Pyroptosis to Alleviate Renal Fibrosis via the mTOR/HIF-1α Pathway

Hirudin, a polypeptide extracted from medicinal leeches, has demonstrated potential in treating renal fibrosis. This study aimed to explore the underlying mechanisms by which Hirudin alleviates renal fibrosis. Renal fibrosis models were established using unilateral ureteral obstruction (UUO) surgery in rats and transforming growth factor-β (TGF-β)-induced HK-2 cells, followed by treatment with different concentrations of Hirudin. Renal function indicators were detected using an automatic analyzer. Renal pathology was observed using hematoxylin-eosin and Masson staining, and α-smooth muscle actin (α-SMA) (a fibrosis marker) expression was detected by immunohistochemistry. Cell viability was tested using cell counting kit-8 assay. Western blot was utilized to detect α-SMA, NOD-like receptor thermal protein domain associated protein 3 (NLRP3), Gasdermin D (GSDMD), cleaved caspase-1, phosphorylated mammalian target of rapamycin (p-mTOR), mammalian target of rapamycin (mTOR), and hypoxia-inducible factor-1α (HIF-1α) levels. Interleukin (IL)-1β and IL-18 levels were measured using enzyme-linked immunosorbent assay (ELISA). UUO rats exhibited impaired renal function and severe renal fibrosis, accompanied by increased NLRP3, GSDMD, cleaved caspase-1, IL-1β, IL-18, p-mTOR/mTOR, and HIF-1α levels. Hirudin alleviated renal fibrosis, reduced pyroptosis, and inhibited mTOR/HIF-1α pathway in UUO rats. TGF-β stimulation decreased cell viability, increased α-SMA expression and pyroptosis, and activated mTOR/HIF-1α pathway in HK-2 cells. These changes were reversed by Hirudin. However, the mTOR agonist MHY1485 altered the effects of Hirudin. In conclusion, Hirudin reduces pyroptosis to alleviate renal fibrosis, potentially by suppressing mTOR/HIF-1α pathway.