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

## TL;DR

This study explores whether rifaximin can protect against liver inflammation and fibrosis in MASH by targeting ethanol-producing gut bacteria.

## Contribution

The study shows that rifaximin's protective effects in MASH are not due to reducing ethanol-producing bacteria but may be due to reducing endotoxemia and inflammation.

## Key findings

- Rifaximin reduced liver inflammation and fibrosis in mice fed a Western diet.
- Rifaximin did not reduce ethanol-producing bacteria or faecal ethanol levels.
- Bacteria isolated from rifaximin-treated mice developed resistance to the drug.

## Abstract

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.