Abstract
Host defense peptides/proteins (HDPs), also known as antimicrobial peptides/proteins (AMPs), are key molecules in the cutaneous innate immune system.
AMPs/HDPs historically exhibit broad-spectrum killing activity against bacteria, enveloped viruses, fungi and several parasites. Recently, AMPs/HDPs
were shown to have important biological functions, including inducing cell proliferation, migration and differentiation; regulating inflammatory responses;
controlling the production of various cytokines/chemokines; promoting wound healing; and improving skin barrier function. Despite the fact that AMPs/HDPs protect our body,
several studies have hypothesized that these molecules actively contribute to the pathogenesis of various skin diseases. For example, AMPs/HDPs play crucial roles
in the pathological processes of psoriasis, atopic dermatitis, rosacea, acne vulgaris, systemic lupus erythematosus and systemic sclerosis. Thus, AMPs/HDPs may be a double-edged sword,
promoting cutaneous immunity while simultaneously initiating the pathogenesis of some skin disorders. This review will describe the most common
skin-derived AMPs/HDPs (defensins, cathelicidins, S100 proteins, ribonucleases and dermcidin) and discuss the biology and both the positive and negative aspects of these AMPs/HDPs
in skin inflammatory/infectious diseases. Understanding the regulation, functions and mechanisms of AMPs/HDPs may offer new therapeutic opportunities in the treatment of various skin disorders.