The Microecological-Immune Axis in Pediatric Allergic Diseases: Imbalance Mechanisms and Regulatory Interventions

In recent years, the global prevalence of pediatric allergic diseases—including atopic dermatitis, allergic rhinitis, and asthma—has increased significantly. Accumulating evidence underscores the pivotal role of the microbiota–immune axis in the regulation of immune tolerance, wherein microbial dysbiosis is a critical driver in the onset and progression of these conditions. Notably, reduced microbial diversity and imbalanced proportions can also cause immune dysregulation and cross-organ signaling. The skin–lung–gut axis has emerged as a key conduit for multi-organ immune communication. Microbial communities at barrier sites not only mediate local immune homeostasis but also influence distant organs through metabolite production and immune signaling pathways, forming a complex network of organ crosstalk. This mechanism is integral to the maintenance of both innate (e.g., epithelial barrier integrity and phagocytic activity) and adaptive (e.g., the Type 1/Type 2 cytokine balance and regulatory T cell function) immunity, thereby suppressing allergic inflammation. Early microbial colonization is crucial for immune system maturation, and its perturbation is strongly linked to abnormal allergic immune responses. As such, the skin–lung–gut axis functions as a cross-organ microecological–immune regulatory network that is particularly relevant in the context of infantile allergic disorders. Intervention strategies targeting the microbiota—including probiotics, prebiotics, synbiotics, and postbiotics—have demonstrated potential in modulating host immunity. Furthermore, emerging approaches such as engineered probiotics, advanced delivery systems, and fecal microbiota transplantation (FMT) offer promising therapeutic avenues. This review provides a comprehensive overview of microbiota development in early life, its association with allergic disease pathogenesis, and the current progress in microbiota-targeted interventions, offering a theoretical foundation for individualized prevention and treatment strategies.