Pyroptosis has an important role in liver inflammation and fibrosis. The role of KC pyroptosis in liver fibrosis was unclear. Ursolic acid (UA) has antifibrotic effects, but study on the effect and mechanism of UA on KC pyroptosis in liver fibrosis has not been reported. Therefore, we induced KC pyroptosis using Lipopolysaccharide (LPS) and nigericin (Nig) in vitro. C57BL/6J mice were intraperitoneally injected with carbon tetrachloride (CCl₄) to establish a liver fibrosis model. We demonstrated that UA attenuated CCl₄-induced liver fibrosis, liver damage, and KC pyroptosis of liver tissue. Moreover, KCs were treated with UA and small interfering RNA of NOX2, which showed that inhibiting the NOX2/NLRP3 inflammasome signaling pathway attenuated KC pyroptosis and UA abrogated this effect via suppressing this pathway in vitro. Furthermore, mice were treated with UA, GSK2795039 (a specific inhibitor of NOX2) or MCC950 (a specific inhibitor of NLRP3). Compared with inhibiting NOX2 alone, inhibiting NOX2 in the presence of UA did not markedly ameliorate KC pyroptosis of liver tissue in CCl₄-induced liver fibrosis. In addition, when NLRP3 was silenced or inhibited, the result was similar to that of knocking down NOX2 in vivo and in vitro. These results indicate that UA attenuates liver fibrosis in mice via inhibiting KC pyroptosis, which may be through the suppression of NOX2/NLRP3 inflammasome signaling pathway. It may be a new target for treating liver fibrosis and provide a new theoretical basis for the use of UA to treat liver fibrosis.

Non‑alcoholic steatohepatitis (NASH), the more progressive form of non‑alcoholic fatty liver disease, has become a major cause of cirrhosis and liver cancer. The aim of the present study was to investigate the anti‑NASH effect of the nonabsorbable antibiotic rifaximin and its specific molecular mechanisms. A methionine‑choline deficient (MCD) diet was used to induce NASH formation in mice. The mice with NASH were treated with rifaximin to observe its effects on liver fat deposition, hepatocyte inflammation and liver fibrosis. Furthermore, the intestinal microbiota of mice with NASH was analysed by 16S rRNA sequencing and terminal ileal bile acid levels were assessed using liquid chromatography‑electrospray ionization‑tandem mass spectrometry analysis. Furthermore, the correlation between the intestinal microflora and bile acid levels in the terminal ileum was investigated, and the effects of rifaximin on the intestinal Helicobacter‑deoxycholic acid (DCA)‑farnesoid X receptor (Fxr)‑hepatocyte nuclear factor 1α (Hnf1α) signalling pathway were examined. Moreover, analyses of mice after intestinal decontamination with broad‑spectrum antibiotics and of hepatocyte‑specific Hnf1α knockout (Hnf1α^H‑KO) mice were used to elucidate the molecular mechanisms by which rifaximin improves NASH. Notably, treatment with rifaximin markedly ameliorated liver steatosis, hepatocyte inflammation and liver fibrosis in mice with MCD diet‑induced NASH. Rifaximin modulated the gut microbiota, especially Helicobacter hepaticus, in mice with NASH. In addition, rifaximin inhibited the intestinal Helicobacter‑DCA‑Fxr‑Hnf1α signalling pathway in mice with NASH. By contrast, rifaximin did not exert an anti‑NASH effect on decontamination‑treated mice or Hnf1α^H‑KO mice. Taken together, these results indicated that rifaximin can ameliorate NASH in mice by modulating the Helicobacter‑DCA‑Fxr‑Hnf1α signalling pathway, providing a theoretical basis for the clinical treatment of patients with NASH with rifaximin.