Mast Cells and Microbiome in Skin Immunity

Abstract

The skin functions as a physical barrier against entry of pathogens while concomitantly supporting a myriad of commensal organisms. The characterization of these microbial communities has enhanced our knowledge of the ecology of organisms present in normal skin, and studies have begun to illuminate the intimate relationship between the host and resident microbes. The cutaneous innate and adaptive immune responses can modulate skin microbiota, while simultaneously, the microbiota educates the host immune system. A crucial element of the innate immune response is mast cells, which reside strategically in tissues that are commonly exposed to the external environment, such as the skin and mucosae. Mast cells are present on the frontline of defense against pathogens, suggesting they may play an important role in fostering the host-microbiota relationship. In this review, we highlight findings regarding the interaction between skin microbiota and mast cells and the resulting outcomes in skin homeostasis.