Innate immune defense system of the skin

Abstract

Antimicrobial peptides exhibit antimicrobial activity against bacteria, viruses, fungi and parasites, with different potencies depending on their peptide structure. They also act as multifunctional effector molecules that influence diverse cellular processes, including cell migration, proliferation and differentiation, cytokine production, angiogenesis and wound healing. Suppressed AMP production has been associated with increased susceptibility to microbial insults and the pathogenesis of atopic dermatitis. This review highlights recent observations on the expression and role of AMPs, particularly the AMPs cathelicidin and β-defensin, in healthy and diseased skin.

Epidermal Permeability Barrier Defects and Barrier Repair Therapy in Atopic Dermatitis

“…Antimicrobial peptides (AMPs) are important molecules involved in the evolutionarily conserved innate immune defense system of the skin against bacteria, viruses, fungi, parasites and tumor cells 53. More than 1,700 AMPs have been identified 54.…”

“…More than 1,700 AMPs have been identified 54. In normal human skin, keratinocytes are the main source of AMPs, and AMP synthesis occurs primarily in the SG 53. In addition to their antimicrobial activity, AMPs in the skin have variable functions, including modulation of host inflammatory responses and promotion of wound healing 55.…”

“…Nomura et al58 proposed that this defect in AD is caused by AMP suppression via elevated levels of T-helper 2 cytokines, IL-4 and IL-13. Lower AMP levels diminished the antimicrobial barrier function in AD subjects, resulting in increased susceptibility to S. aureus and other microbial superinfections, such as eczema herpeticum 53,59. In fact, LL-37 exhibited antiviral activity against herpes simplex virus (HSV), and mice deficient in the LL-37 homologue showed higher levels of HSV-2 replication in their skin.…”

Effective Treatment of Staphylococcal Scalded Skin Syndrome with Platelet Microbicidal Protein in CBRB-Rb(8.17)1Iem Mice Model

“…The virulence factors produced by S. aureus have a wide array of biological properties, including disruption of the epithelial barrier, inhibition of opsonization by antibody and complement, interference with neutrophil chemotaxis, cytolysis of neutrophils, and inactivation of antimicrobial peptides [7]. The innate immune system of the epidermis is the first line of defense against invasion by microorganisms, which gain entry after the skin is damaged [1]. Antimicrobial peptides (AMPs) form part of this defense system.…”

Human skin engages different epidermal layers to provide distinct innate defense mechanisms

“…Antimicrobial peptides (AMP) and cytokines are important defense mediators of cutaneous innate immunity . Upon recognition of microorganisms, human keratinocytes are able to initiate a rapid defense reaction by the production and release of AMP and cytokines .…”