Role of Human Skin Antimicrobial Peptides in Psoriasis

Introduction. Psoriasis is a chronic inflammatory skin disease with various biochemical, immunologic and vascular changes, and a vague relationship to nervous system function. Skin defends the body by rapidly setting an innate immune response and providing a swift first–line defense against infection or injury. Hundreds of naturally occurring antimicrobial peptides have been discovered and it has been shown that psoriatic epidermis expresses high levels of host defense proteins.
Aim of the Study. To evaluate human antimicrobial peptides in correlation with inflammation level in skin biopsy material of psoriatic lesions.
Materials and methods. We evaluated 9 psoriasis patients and 1 healthy volunteer. Skin biopsies were obtained from using the routine punch biopsy method. All tissue specimens were stained with hematoxylin and eosin and by immunochemistry for human β defensin 2, PGP 9.5, MMP2. The intensity of immunostaining was graded semiquantitatively. For apoptosis evaluation, we used TUNEL method. Results. We found a distinct inflammatory cell infiltration with diffusive character in subepithelial layer, epithelium and hair follicle outer epithelial sheath. Defensin–containing cell number, PGP 9.5–containing nerve fibers and number of MMP2 positive macrophages, fibroblasts and epitheliocytes varied from few to abundant in the visual field. Apoptosis affected epithelial cells, connective tissue cells and inflammatory cells focally.
Conclusions. Histological findings vary from marked inflammatory cell infiltration to granulation tissue. Psoriatic lesions of patients with no previous active psoriasis treatment feature marked activation of defensin, matrix metalloproteinase, apoptosis and neuropeptides–containing innervation. In skin of psoriasis patients with long–term ineffective treatment psoriatic lesions show abundance of positive structures of defensin, matrix metalloproteinase and neuropeptides–containing innervation. Close correlation between expression of defensin–containing cells, apoptotic cells, and inflammation in the skin was found suggesting about possible stimulation of AMPs and apoptosis by specific inflammation.