Human skin engages different epidermal layers to provide distinct innate defense mechanisms

Keratinocytes are able to sense bacteria or bacterial products leading to a rapid defense reaction by the increased expression of antimicrobial peptides and cytokines. Recent data by Percoco and collaborators published in Experimental Dermatology indicate that bacteria colonizing the skin surface induce a differential spatial expression pattern of antimicrobial peptides and cytokines. Using laser capture microdissection followed by real‐time PCR as well as immunohistochemistry and transmission electron microscopy, the authors provide evidence that antimicrobial peptides such as human beta‐defensin (hBD)‐2 and ‐3 were more strongly induced in the uppermost epidermal layers, whereas the main induction of cytokines such as IL‐1beta and IL‐6 occurred in the lower parts of the epidermis.