Gut microbiota and metabolite transport-mediated regulation of Th1/Th2 balance by Saposhnikovia divaricata-Mume Fructus in alleviating allergic asthma

Objective To investigate the protective effects of Fangfeng (Saposhnikovia divaricata) and Wumei (Prunus mume) (FW) on ovalbumin (OVA)-induced allergic asthma in mice and explore the underlying mechanisms.Methods A mouse model of allergic asthma was established by ovalbumin (OVA) sensitization combined with aerosol challenge. Mice were administered different doses of Fangfeng-Wumei (FW). Lung tissue histopathology was evaluated using H&E and PAS staining. Levels of inflammatory cytokines in serum and bronchoalveolar lavage fluid (BALF) were measured by ELISA. Oxidative stress in lung tissue was assessed by measuring the levels of GSH and SOD activity. Simultaneously, the gut microbiota composition was analyzed by 16S rRNA sequencing, and short-chain fatty acids (SCFAs) as well as the expression of their transporters SMCT1 (sodium-coupled monocarboxylate transporter 1) and MCT1 (monocarboxylate transporter 1) were measured.Results OVA-induced mice exhibited typical airway inflammation, including disrupted alveolar structure, inflammatory cell infiltration, mucosal edema, and excessive mucus secretion. Meanwhile, Th2-type cytokines (IL-4, IL-5, IL-13) in serum and bronchoalveolar lavage fluid (BALF) were elevated, IFN-γ was decreased, and lung tissue showed reduced GSH content and SOD activity. Gut microbiota diversity was decreased, and SCFA levels in cecal contents were reduced. Intervention with FW significantly alleviated lung inflammation and structural damage, suppressed mucus secretion, regulated Th1/Th2 immune balance, increased GSH content and SOD activity, restored gut microbiota homeostasis, elevated SCFA levels, and upregulated SMCT1/MCT1 protein expression.Conclusion FW effectively alleviated lung and intestinal injury in OVA-induced allergic asthma mice by modulating airway immune responses, enhancing antioxidant capacity, and improving gut microbiota composition and metabolites. This provides supportive evidence for the use of natural compounds in the intervention of allergic asthma.