CD44 expression in human skin: high expression in irritant and allergic contact dermatitis and moderate expression in psoriasis lesions in comparison with healthy controls

Background Previous research using animal models demonstrated that CD44 expression may contribute to directing inflammatory cells into skin lesions during inflammation development in allergic contact dermatitis (ACD). Objectives To examine CD44 expression in patients with ACD and irritant contact dermatitis (ICD), and to compare it to patients with psoriatic lesions and healthy controls' (HCs) skin. Methods This study included 200 patients comprising four groups of 50 each: ACD, ICD, psoriasis vulgaris, and HCs. CD44 expression was determined by immunohistochemical analysis using an optical microscope, and the results were visualized semiquantitatively by determining the percentage of immunoreactive cells in the epidermis, dermis, and on lymphocytes. Results The highest CD44 expression was found in ICD, followed by ACD, psoriasis vulgaris, and lastly, the HCs (P < .001). Epidermal CD44 expression was significantly higher in contact dermatoses (especially in ICD) compared with psoriasis and healthy skin (P < .001). Similarly, CD44 expression in the dermis and on lymphocytes was strongest in ICD, although less pronounced than in the epidermis. Conclusions Because significantly elevated CD44 expression in ICD might be related to its function in maintaining and preserving the skin barrier in affected patients, further research on disease pathogenesis and new treatment options is needed.