Microbiota and maintenance of skin barrier function

Human skin forms a protective barrier against the external environment and is our first line of defense against toxic, solar, and pathogenic insults. Our skin also defines our outward appearance, protects our internal tissues and organs, acts as a sensory interface, and prevents dehydration. Crucial to the skin’s barrier function is the colonizing microbiota, which provides protection against pathogens, tunes immune responses, and fortifies the epithelium. Here we highlight recent advances in our understanding of how the microbiota mediates multiple facets of skin barrier function. We discuss recent insights into pathological host–microbiota interactions and implications for disorders of the skin and distant organs. Finally, we examine how microbiota-based mechanisms can be targeted to prevent or manage skin disorders and impaired wound healing.