New strain of alleviates ethanol-induced liver injury by modulating the gut microbiota and short-chain fatty acid metabolism.

BACKGROUND

Intestinal dysbiosis has been shown to be associated with the pathogenesis of alcoholic liver disease (ALD), which includes changes in the microbiota composition and bacterial overgrowth, but an effective microbe-based therapy is lacking. () CGMCC 7049 is a newly isolated strain of probiotic that has been shown to be resistant to ethanol and bile salts. However, further studies are needed to determine whether exerts a protective effect on ALD and to elucidate the potential mechanism.

AIM

To evaluate the protective effect of the probiotic on ethanol-induced liver injury in mice.

METHODS

A new ethanol-resistant strain of CGMCC 7049 was isolated from healthy adults in our laboratory. The chronic plus binge model of experimental ALD was established to evaluate the protective effects. Twenty-eight C57BL/6 mice were randomly divided into three groups: The control group received a pair-fed control diet and oral gavage with sterile phosphate buffered saline, the EtOH group received a ten-day Lieber-DeCarli diet containing 5% ethanol and oral gavage with phosphate buffered saline, and the group received a 5% ethanol Lieber-DeCarli diet but was treated with . One dose of isocaloric maltose dextrin or ethanol was administered by oral gavage on day 11, and the mice were sacrificed nine hours later. Blood and tissue samples (liver and gut) were harvested to evaluate gut barrier function and liver injury-related parameters. Fresh cecal contents were collected, gas chromatography-mass spectrometry was used to measure short-chain fatty acid (SCFA) concentrations, and the microbiota composition was analyzed using 16S rRNA gene sequencing.

RESULTS

The treatment improved ethanol-induced liver injury, with lower alanine aminotransferase, aspartate transaminase and triglyceride levels and decreased neutrophil infiltration. These changes were accompanied by decreased levels of endotoxin and inflammatory cytokines, including interleukin-5, tumor necrosis factor-α, granulocyte colony-stimulating factor, keratinocyte-derived protein chemokine, macrophage inflammatory protein-1α and monocyte chemoattractant protein-1. Ethanol feeding resulted in intestinal dysbiosis and gut barrier disruption, increased relative abundance of potentially pathogenic and , and the depletion of SCFA-producing bacteria, such as , and . In contrast, administration increased the microbial diversity, restored the relative abundance of and and increased propionic acid and butyric acid production by modifying SCFA-producing bacteria. Furthermore, the levels of the tight junction protein ZO-1, mucin proteins (mucin [MUC]-1, MUC-2 and MUC-4) and the antimicrobial peptide Reg3β were increased after probiotic supplementation.

CONCLUSION

Based on these results, the new strain of alleviated ethanol-induced liver injury by reversing gut microbiota dysbiosis, regulating intestinal SCFA metabolism, improving intestinal barrier function, and reducing circulating levels of endotoxin and proinflammatory cytokines and chemokines. Thus, this strain is a potential probiotic treatment for ALD.