Keratinocyte

Epithelial cell constituting 90% of the epidermis. It synthesises keratin, vitamin D (under UV effect), inflammatory cytokines and antimicrobial peptides. Its renewal is regulated by vitamin A. It expresses TLR4 receptors (activated by LPS) and AhR receptors (activated by microbial metabolites), making the keratinocyte a direct actor in the gut-skin axis.