Oryzanol Ameliorates MCD-Induced Metabolic dysfunction-associated Steatohepatitis in Mice via Gut Microbiota Reprogramming and TLR4/NF-κB Signaling Suppression

Introduction: Metabolic dysfunction-associated steatohepatitis (MASH) has emerged as a major global health concern that affects about a quarter of the global population. Recently, host-gut microbiota metabolic interactions have emerged as key mechanistic pathways in MASH development. Oryzanol (ORY), rice bran bioactive compound, exhibits antioxidant, anti inflammatory, hypolipidemic and hypoglycemic properties. Here, we investigated the potential of ORY in alleviating MASH and its association with gut microbiota and MASH progression. Methods: Male C57BL/6J mice were fed normal chow diet or methionine-choline-deficient diet and received ORY supplementation at 300 mg/kg/day via gavage for 4 weeks. Liver injury, inflammation, lipid accumulation and TLR4/NF-κB Signaling protein levels were assessed. Additionally, changes in gut microbiota diversity and abundance across groups were evaluated using 16S rDNA sequencing. Results: Our results demonstrated that ORY significantly reduced lipid accumulation and liver enzymes, ameliorated liver and ileum damage, and restored intestinal barrier function in MASH mice. Furthermore, ORY decreased plasma LPS levels, inflammatory cytokines and downregulated TLR4, MyD88, and NF-κB protein levels in the liver. ORY enhanced tight junction protein level (ZO-1, occludin) in the gut. Microbial analysis revealed that ORY positively impacted Firmicutes and Bacteroidetes abundance, promoted beneficial bacteria like Lactobacillus and Lachnospiraceae_NK4A136_group, and inhibited harmful bacteria such as Mucispirillum, Bacteroides, and Colidextribacter. Notably, ORY increased Akkermansia abundance, potentially modulating metabolic and inflammatory pathways. Conclusion: ORY exerted restorative and reversible effects on the pathophysiological damage within gut–liver axis in MASH mice. The therapeutic mechanism may be related to the modulation of the gut microbiota and TLR4/NF-κB signaling pathway.