RNase 7 participates in cutaneous innate control of Corynebacterium amycolatum

Nondiphtheria corynebacteria are typical members of the skin microbiota. However, in addition to being harmless inhabitants of healthy skin commensal skin-derived corynebacteria such as C. amycolatum occasionally also cause infections. This suggests that human skin must harbor adequate mechanisms to control the growth of corynebacteria on the skin surface. Here we show that keratinocytes are able to detect the presence of C. amycolatum leading to the epidermal growth factor receptor (EGFR)-dependent induction of the antimicrobial protein RNase 7. C. amycolatum-mediated induction of RNase 7 was also confirmed in a human 3D skin equivalent. The functional relevance of these findings was demonstrated by potent antimicrobial activity of RNase 7 against C. amycolatum and C. xerosis. In addition, the capacity of human stratum corneum to restrict the growth of C. amycolatum was significantly attenuated when RNase 7 was inactivated by a specific RNase 7-neutralizing antibody. Taken together, the interaction of RNase 7 with C. amycolatum indicates that RNase 7 may function as important effector molecule to control the growth of corynebacteria on human skin.