# Lactobacillus helveticus HY7804 Modulates the Gut–Liver Axis to Improve Metabolic Dysfunction-Associated Steatotic Liver Disease in a Mouse Model

## TL;DR

This study shows that Lactobacillus helveticus HY7804 improves liver disease and gut health in mice by modulating gut bacteria and reducing inflammation.

## Contribution

The novel finding is that HY7804 modulates gut microbiota and intestinal barrier function to alleviate MASLD symptoms.

## Key findings

- HY7804 reduced MASLD activity scores and improved blood biochemical indicators in mice.
- HY7804 increased fatty acid oxidation genes and decreased pro-inflammatory signaling in the gut.
- HY7804 altered gut microbiota composition, increasing beneficial bacteria and reducing harmful ones.

## Abstract

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most common type of liver disease worldwide. In a previous study, we confirmed that Lactobacillus helveticus HY7804 (HY7804) improves MASLD by suppressing the expression of mRNAs encoding genes related to hepatic lipogenesis, inflammation, and fibrosis in model mice. Here, we evaluated the ability of HY7804 to restore intestinal barrier function and modulate the gut microbiota, as well as improve MASLD symptoms. Mice fed an MASLD-inducing diet for 7 weeks received HY7804 (109 CFU/kg/day), the Type strain, or positive control (Pioglitazone) during the same period. HY7804 alleviated physiological (p < 0.001) and blood biochemical indicators and reduced MASLD activity scores (p < 0.05) on histological analysis. In addition, HY7804 increased the expression of genes related to fatty acid oxidation (p < 0.001); decreased the expression of apoptosis-related genes (p < 0.001); rescued the expression of tight junction (TJ)-related genes (p < 0.05); and suppressed the expression of pro-inflammatory cytokines and TLR4/MyD88/NF-κB signaling (p < 0.01) in the intestine. Finally, HY7804 modulated the composition of the gut microbiota in MASLD-induced mice. HY7804 increased the abundance of MASLD-suppressive Bacteroidaceae and Bacteroides, which positively correlated with the expression of TJ- and fatty acid oxidation-related genes. By contrast, HY7804 decreased the abundance of bacteria related to the progression of MASLD, including Cloastridaceae, Clostridium, Streptococcaceae, Lactococcus, and Lachnospiraceae, which correlated with intestinal immune responses and MASLD symptoms. In conclusion, L. helveticus HY7804 may be suitable as a functional supplement that alleviates MASLD symptoms and improves intestinal health.