Role of skin antimicrobial peptides in the pathogenesis of psoriasis, atopic dermatitis and hidradenitis suppurative: Highlights on dermcidin

Diverse classes of antimicrobial peptides (AMPs) produced by keratinocytes, sebocytes, epithelial cells of apocrine and eccrine sweat glands and innate immune cells are continually released in the skin tissue layers. Together they exert the fine homeostatic control of the host immune cells-skin microbiome interactions, inhibiting bacterial overgrowth and skin barrier disruption. Under a variety of pathological conditions, up or down regulation of AMP expression can contribute to microbial diversity imbalance or dysbiosis, which can initiate or worsen the most common cutaneous diseases. This review updates on the roles of dermcidin, defensins, cathelicidins and S100 proteins as modulators of microbiomes, inflammation and recurrent bacterial infections in psoriasis, atopic dermatitis and hidradenitis suppurativa. The top most significant disease-immune signaling pathways mediated by the cytokines IL-1, TNF-α, IL-17, IL-23 and IL-33 are also reviewed. Current studies suggest that raising and lowering of host cell- and bacterial-derived AMPs may directly affect microbiome and immunity homeostasis at local body sites. Molecular genetics and microbiome studies should help us to investigate the bacterial species and AMPs synergistic or harmful interactions with causal gene variants, harnessing their potential clinical application in the journey of skin disease patients.