IL-17 Control of Cutaneous Immune Homeostasis.

IL-17 is widely recognized for its roles in host defense and inflammatory disorders. However, it has become clear that IL-17 is also an essential regulator of barrier tissue physiology. Steady-state microbe sensing at the skin surface induces low-level IL-17 expression that enhances epithelial integrity and resists pathogens without causing overt inflammation. Recent reports describe novel protective roles for IL-17 in wound healing and counteracting physiologic stress; however, chronic amplification of these beneficial responses contributes to skin pathologies as diverse as fibrosis, cancer, and autoinflammation. In this paper, we discuss the context-specific roles of IL-17 in skin health and disease and therapeutic opportunities.