Effects of ultraviolet B radiation on cytoskeletal and adhesion molecules in human epidermis

The expression of cytokeratins (CK), various adhesion molecules and growth factor receptors were investigated in ultraviolet (UV) erythemas 24 h and 48 h after exposure to 4 times the minimal erythema dose. Skin biopsies were analysed immunohistochemically using a battery of antibodies and biochemically by gel-electrophoresis. The CK pattern was shown to change within 24 h. CK typical of basal keratinocytes were detectable heterogeneously within the suprabasal compartment, and the staining for suprabasal CK was heterogeneous in prickle cells. Interestingly, CK 17, not detectable in normal epidermis, was induced within a few hours in suprabasal cells but not in basal ones. In addition, CK 6 and 16, typical for hyperproliferation, were intensively synthesized in all epidermal layers already 24 h after UV exposure. Moreover, integrin expression was studied and surprisingly integrins were heterogeneously detectable, the staining being patchy in suprabasal keratinocytes and reduced within the basal layer. Receptors of epidermal growth factor and nerve growth factor were distributed in UV erythema very irregularly and weakly. Our findings argue for profound changes in composition of cytoskeleton and of cell adhesion molecules in the epidermis shortly after UV exposure.