β-sitosterol attenuates hepatic lipid accumulation and fibrosis via NLRP3 signaling in MASH mice.

Β-sitosterol (SIT), a natural phytosterol, has not been fully explored for its therapeutic potential in metabolic dysfunction-associated steatohepatitis (MASH). In this study, MASH was induced in mice via a high-fat, high-cholesterol (HFHC) diet, and lipid accumulation in HepG2 cells was triggered with oleic acid (OA), while the role of the NLRP3 inflammasome was explored in NLRP3-knockout (NLRP3^-/-) mice treated with or without SIT. SIT treatment significantly alleviated HFHC-induced hepatic injury, evidenced by reduced alanine aminotransferase and aspartate aminotransferase levels, improved liver histology, and decreased hepatocyte apoptosis. SIT also reduced hepatic triglyceride and cholesterol levels, inhibited lipid droplet accumulation, and modulated genes involved in lipogenesis and β-oxidation. Furthermore, SIT reduced hepatic inflammation by decreasing macrophage and neutrophil infiltration and suppressing pro-inflammatory cytokines (IL-6, IL-1β, TNF-α). SIT also exhibited antifibrotic effects, confirmed by histological and gene expression analysis. Mechanistically, SIT inhibited NLRP3 inflammasome activation, with diminished hepatoprotective effects in NLRP3^-/- mice. In conclusion, SIT offers potent hepatoprotective effects in MASH, likely through NLRP3 inflammasome inhibition, positioning it as a promising therapeutic candidate for MASH.