Antimicrobial Peptides Human β-Defensins Stimulate Epidermal Keratinocyte Migration, Proliferation and Production of Proinflammatory Cytokines and Chemokines

Abstract

Besides their microbicidal functions, human beta-defensins (hBD) and LL-37 activate different immune and inflammatory cells, and their expression is enhanced in inflamed skin and cutaneous wound sites. To protect against pathogens, the skin produces antimicrobial peptides including hBDs and LL-37. Therefore, the aim of our study was to investigate whether hBDs participate in cutaneous inflammation and wound healing by inducing keratinocyte migration, proliferation, and production of proinflammatory cytokines/chemokines. We found that hBD-2, -3, and -4 but not hBD-1 stimulated human keratinocytes to increase their gene expression and protein production of IL-6, IL-10, IP-10, monocyte chemoattractant protein-1, macrophage inflammatory protein-3alpha, and RANTES. This stimulatory effect was markedly suppressed by pertussis toxin and U-73122, inhibitors for G protein and phospholipase C, respectively. We also demonstrated that hBDs elicited intracellular Ca2+ mobilization, and increased keratinocyte migration, and proliferation. In addition, these peptides induced phosphorylation of EGFR, signal transducer and activator of transcription (STAT)1, and STAT3, which are intracellular signaling molecules involved in keratinocyte migration and proliferation. In our study, inhibition of these molecules significantly reduced hBD-mediated keratinocyte migration and proliferation. In conclusion, this study provides evidence that human antimicrobial peptides may be involved in skin immunity through stimulating cytokine/chemokine production, and participate in wound healing by promoting keratinocyte migration and proliferation.

IL‐12, IL‐23, and IL‐27 enhance human β‐defensin‐2 production in human keratinocytes

“…Such keratinocytes, when exposed to microbes like gram-negative bacteria, may deposit the concentrated hBD-2 onto the surface-bound microbes and kill them [36]. The released hBD-2 may in turn act on keratinocytes [8] and induce the production of pro-inflammatory cytokines/chemokines by these cells in an autocrine/paracrine manner. This is the first study showing that epidermal keratinocytes are directly targeted by APCderived cytokines -IL-12, IL-23, and IL-27.…”

“…Human b-defensin-2 (hBD-2), an antimicrobial peptide, is produced by epidermal keratinocytes, and its production is enhanced in cutaneous infection or inflammatory diseases such as psoriasis vulgaris [7,8]. hBD-2 kills gram-negative bacteria and protects skin against infection with these bacteria [9].…”

“…hBD-2 kills gram-negative bacteria and protects skin against infection with these bacteria [9]. In addition, hBD-2 potentiates skin inflammation: It binds to CCR6 and induces chemotaxis of memory T cells or immature DC [10] and induces the production of IL-6, CCL20, CXCL10, and CCL5 in keratinocytes [8].…”

Innate Immune Defense System of the Skin

“…81 Human BD2, hBD3 and hBD4 stimulate keratinocytes to increase their gene expression of many proinflammatory cytokines, chemokines and proteins, including interleukin-6, interleukin-10, monocyte chemoattractant protein-1 and macrophage chemoattractant protein-1. 82 Human BDs also elicit intracellular Ca 2+ mobilization and participate in wound repair by increasing keratinocyte migration and proliferation. 82 Of note, a mutation of a BD in dogs has been associated with coat colour.…”

Novel Insight Into the Role of Antimicrobial (Host Defense) Peptides/Proteins in Human Skin Diseases

“…These peptides bind to specific pertussis toxin-sensitive G protein-coupled receptors (GPCRs) such as the CC chemokine receptor 2 (CCR2), CCR6, Mas-related G-protein coupled receptor X2 (MrgX2), and other GPCRs which have yet to be identified 2) 24) 29)-32) . hBDs also utilize Toll-like receptor (TLR) 1 and TLR2 to stimulate a variety of immune cells 33) , and transactivate the membrane-bound epidermal growth factor receptor (EGFR) to promote keratinocyte migration and proliferation 22) .…”