DIFFERENTIAL EXPRESSION OF THE VERSICAN AND DECORIN GENES IN PHOTOAGED AND SUN-PROTECTED SKIN - COMPARISON BY IMMUNOHISTOCHEMICAL AND NORTHERN ANALYSES

BACKGROUND: Chronic sun exposure induces numerous changes in exposed s kin; the most striking histopathologic change is the massive accumulat ion of material with the staining characteristics of elastin, termed s olar elastosis, in the superficial dermis. Previous studies have ident ified elastic fibers within areas of solar elastosis, as well as a dec rease in collagen content. Recently, the large chondroitin sulfate (CS ) proteoglycan, versican, has been identified in the dermis in associa tion with elastic fibers, and the smaller CS proteoglycan, decorin, ha s been shown to codistribute with collagen fibers. Thus, changes in ex pression of these CS proteoglycans might be expected in photoaging and may help to explain the clinical alterations of chronically sun-expos ed skin. EXPERIMENTAL LESION: Immunohistochemical staining and confoca l laser scanning microscopy for versican and decorin was performed on paired tissue samples from photoaged and non-sun-exposed skin taken fr om the same individuals. To investigate versican and decorin mRNA expr ession, Northern analysis was performed on paired fibroblast cultures derived from tissue explants of photoaged and non-sun-exposed skin. RE SULTS: Immunohistochemical staining and confocal laser scanning micros copy revealed a massive accumulation of versican localized to the abno rmally large fibers comprising solar elastosis in the superficial and mid-dermis of photoaged specimens. Decorin staining was greatly decrea sed within the area of solar elastosis. Similarly, changes in mRNA wer e measured from fibroblast cultures, with a significant increase in ve rsican mRNA in cultures derived from photoaged skin, whereas decorin m RNA levels were significantly decreased in photoaged skin. CONCLUSIONS : This study provides further evidence for the close association of ve rsican with elastic fibers and decorin with collagen fibers, even in t he situation of abnormal fiber deposition occurring in photodamaged sk in. In addition, changes in versican and decorin immunostaining are ac companied by similar alterations in gene expression.