Baicalein mitigates epithelial barrier impairment and microbiota dysbiosis in allergic asthmatic mice via the gut‑lung axis

BACKGROUND: Allergic asthma (AA) may result in repeated episodes of chest constriction and coughing. In its most serious manifestations, it can cause death by asphyxiation. Currently, no efficacious therapeutic interventions exist to avert or counteract these serious outcomes. Baicalein (BAI) is a core quality marker of the traditional Chinese medicine Scutellaria baicalensis, but the mechanism of its oral action remains unclear. OBJECTIVE: Assess the therapeutic efficacy of BAI in AA mice models and investigate its mechanism of action. STUDY DESIGN AND METHODS: Evaluate the efficacy of BAI on ovalbumin-induced AA mice. To assess alterations in the pulmonary and gut microbial communities, 16S rRNA sequencing was employed. The integrity and restoration of the lung and intestinal epithelial lining were evaluated via immunohistochemistry. Furthermore, gas chromatography-mass spectrometry quantified fecal levels of short-chain fatty acids (SCFAs) in AA mice, and flow cytometry was used to analyze the content of ILC2 cells in colon tissue. Finally, the role of beneficial bacteria and their metabolites in inhibiting AA was further confirmed through fecal microbiota transplantation (FMT). RESULTS: Oral BAI effectively alleviated AA-related lung epithelial damage and microbiota dysbiosis, while elevating the production of the tight junction proteins. Moreover, BAI mitigated colonic epithelial damage, inhibited ILC2s activation in the colon, enriched the abundance of gut probiotics capable of producing SCFAs, especially Akkermansia muciniphila (A. muciniphila), and increased the content of SCFAs such as propionic acid in feces. The FMT experiment conducted after gavage with broad-spectrum antibiotics confirmed that BAI mediated reversal of microbial dysbiosis plays a key role in the treatment of AA, significantly increasing the expression of GPR41 mRNA in colon tissue and inhibiting the activation of ILC2s. CONCLUSION: The potential prebiotic BAI mitigates AA via targeting A. muciniphila and its metabolites, which consequently inhibits epithelial damage and type 2 immune activation.