Redefining The Skin Barrier: A Microbiome-Integrated Multilayered Defense Model

This review explores the complex multilayered defense system of the skin, which includes physical, chemical, immune, and microbial barriers. It highlights how these barriers work together to maintain skin homeostasis. The physical barrier provides structural integrity, while the chemical barrier uses an acidic pH, antimicrobial peptides, and microbiota-derived metabolites to deter pathogens. Immune cells like Langerhans cells and T-cells offer immune surveillance, and the microbial barrier, maintained by commensal organisms, supports host defense. The review emphasizes the interconnectedness of these barriers, where dysfunction in one can lead to widespread issues, underscoring the importance of holistic approaches in treating skin disorders and restoring barrier function.