Gut microbiota in asthma: mechanisms, clinical evidence, and therapeutic opportunities

Asthma is a heterogeneous chronic airway inflammatory disease associated with high global prevalence and substantial clinical burden. Conventional therapies remain limited in controlling refractory phenotypes and preventing disease progression. The gut-lung axis has emerged as a fundamental regulatory network connecting intestinal homeostasis with pulmonary immune function, and mounting evidence has established a close mechanistic link between gut dysbiosis and the onset, persistence, and exacerbation of asthma. This review comprehensively integrates evidence from epidemiological investigations, animal models, clinical observational studies, and randomized controlled trials published between 2011 and 2025 to elucidate the crosstalk mechanisms of the gut-lung axis in asthma, characterize compositional and functional alterations of the gut microbiome, evaluate microbiota-targeted interventions such as probiotics, prebiotics, synbiotics, postbiotics, and fecal microbiota transplantation, and discuss current translational challenges. We highlight that the gut microbiota orchestrates airway inflammatory responses through fine-tuning immune cell differentiation, mediating microbial metabolite signaling, and maintaining intestinal barrier function, with discernible microbial signatures evident across allergic versus non-allergic and pediatric versus adult asthma phenotypes. Despite promising preclinical and preliminary clinical findings, causal evidence remains insufficient, and intervention heterogeneity limits clinical application. This review underscores the potential of microbiome-based precision strategies and identifies key directions for future mechanistic research and clinical translation.