Rifaximin Protects Against Inflammation and Fibrosis in MASH: Any Role for Ethanol-Producing Bacteria?

Metabolic Dysfunction-Associated Steato-Hepatitis (MASH) is a multiple-hit disease. Endotoxins, ethanol, and other metabolites of certain gut microbiota can reach the liver and accelerate inflammation and disease progression. Targeting ethanol-producing colonic bacteria with rifaximin could affect the progress of MASH. In the present study, thirty mice were assigned to three groups (n = 10 mice per group). Mice received either a normal diet, a Western diet, or a Western diet with oral rifaximin. After 12 weeks, liver function, serum levels of TNF-α, interleukin (IL)-1β, IL-6, and lipopolysaccharides (LPS) were measured. Liver specimens were assessed for pathological changes, lipid deposition, and fibrosis. Expression of p53, GFAP, CD68, and TLR-4 in the liver was also assessed. Faecal samples were evaluated for ethanol contents. Lactobacillus acidophilus, in addition to ethanol-producing Klebsiella pneumoniae and Escherichia coli, were isolated, quantified, and tested for sensitivity to rifaximin. Rifaximin was able to ameliorate Western diet-induced biochemical changes and elevated TNF-α, IL-1β, IL-6, and LPS levels. Changes in liver histology, fibrosis, and lipid content were attenuated. Expressions of p53, GFAP, CD68, and TLR-4 in the liver were all reduced. The Western diet-induced increases in faecal ethanol or ethanol-producing bacteria were not corrected by rifaximin. After 12 weeks, isolated bacteria from the rifaximin group were rifaximin-resistant. Our findings imply that the protective impact of rifaximin in the MASH model is unlikely to be mediated by alteration of ethanol-producing colonic bacteria because of acquired rifaximin resistance. Rifaximin-induced reduction in endotoxemia and inflammation in the liver appears to be a more relevant explanation.