Mechanism of Qingfei Litan Formula in Improving Acute Lung Injury in Mice by Regulating Gut Microbiota and Short-chain Fatty Acids Metabolism

OBJECTIVE  To analyze the characteristics of gut microbiota in mice with acute lung injury(ALI) and the intervention effect of Qingfei Litan formula, to explore the correlation between changes in gut microbiota and lung inflammation, oxidative stress, and short-chain fatty acids(SCFAs) metabolism, thereby revealing the mechanism of action of Qingfei Litan formula.

METHODS  The ALI mouse model was established via lipopolysaccharide(LPS) tracheal instillation after administering different doses of Qingfei Litan formula. After euthanasia, inflammatory cells and factors in broncho-alveolar lavage fluid(BALF) examined lung pathology were evaluated, the lung coefficient and wet/dry ratio were calculated, oxidative stress markers in lung tissues were assessed, SCFAs content in serum were measured, and 16S rRNA sequencing of the intestinal microbiota were conducted.

RESULTS  Qingfei Litan formula alleviated alveolar damage and pulmonary edema in ALI mice, reduced inflammatory cells and factors in BALF, decreased malondialdehyde in lung tissue, increased superoxide dismutase and glutathione peroxidase activities, and elevated SCFAs in blood. It enhanced gut microbiota Alpha diversity, increased the relative abundance of beneficial bacteria like Lachnospiraceae NK4A136, Lactobacillus, Prevotellaceae UCG-001, Prevotellaceae NK3B31, Ruminiclostridium 6, Enterorhabdus, Ruminococcaceae UCG-013, and decreased harmful bacteria like Alloprevotella, Erysipelatoclostridium, Peptococcus. Correlation analysis revealed that the relative abundances of seven beneficial bacterial genera exhibited negative correlations with both pulmonary inflammation and oxidative stress levels, while showing positive correlations with the contents of acetate, propionate, and butyrate in the blood. Among these, only three beneficial bacterial genera demonstrated positive correlations with valerate content. Conversely, harmful bacterial genera showed opposite correlation patterns. Additionally, acetate, propionate, and butyrate were negatively correlated with inflammatory cytokines and oxidative stress levels in BALF, whereas valerate was only negatively correlated with the levels of inflammatory cytokines(IL-6, IL-1β) in BALF.

CONCLUSION Qingfei Litan formula may exert anti-inflammatory and anti-oxidative stress effects by regulating gut microbiota and SCFAs metabolism, thereby protecting lung tissue in acute lung injury mice.