The skin microbiome-immune-barrier axis: implications for inflammatory skin disorders and immunotherapeutic strategies.

The skin microbiome is a complex and dynamic ecosystem that plays a pivotal role in maintaining skin barrier integrity and immune homeostasis. This review provides a comprehensive synthesis of current knowledge on the composition, diversity, and functional significance of the skin microbiota, with particular emphasis on site-specific and temporal variations, as well as intrinsic and extrinsic factors influencing microbial balance. Relevant literature was identified through comprehensive searches of PubMed, Scopus, Web of Science, and Google Scholar databases covering publications from 2018 to 2026. We discuss the multilayered architecture of the skin barrier, encompassing chemical, physical, microbial, and adaptive immune components, and highlight how commensal microorganisms contribute to barrier maintenance, lipid homeostasis, immune modulation, and colonization resistance against pathogens. Dysbiosis of the skin microbiome is critically examined in common dermatological disorders, including wound infections, atopic dermatitis, acne, and psoriasis, where microbial imbalance is closely linked to inflammation and disease progression. This review further explores emerging microbiome-targeted therapeutic strategies aimed at restoring microbial equilibrium and strengthening skin barrier function. Emerging therapies including bacteriotherapy, probiotics, phage therapy, and microbiome transplantation show promise, while challenges involving safety, ethics, and clinical translation remain important considerations.