Background: Chronic sun exposure induces numerous changes in exposed skin; the most striking histopathologic change is the massive accumulation of material with the staining characteristics of elastin, termed solar elastosis, in the superficial dermis. Previous studies have identified elastic fibers within areas of solar elastosis, as well as a decrease in collagen content. Recently, the large chondroitin sulfate (CS) proteoglycan, versican, has been identified in the dermis in association with elastic fibers, and the smaller CS proteoglycan, decorin, has been shown to codistribute with collagen fibers. Thus, changes in expression of these CS proteoglycans might be expected in photoaging and may help to explain the clinical alterations of chronically sun-exposed skin.
Experimental design: Immunohistochemical staining and confocal laser scanning microscopy for versican and decorin was performed on paired tissue samples from photoaged and non-sun-exposed skin taken from the same individuals. To investigate versican and decorin mRNA expression, Northern analysis was performed on paired fibroblast cultures derived from tissue explants of photoaged and non-sun-exposed skin.
Results: Immunohistochemical staining and confocal laser scanning microscopy revealed a massive accumulation of versican localized to the abnormally large fibers comprising solar elastosis in the superficial and mid-dermis of photoaged specimens. Decorin staining was greatly decreased within the area of solar elastosis. Similarly, changes in mRNA were measured from fibroblast cultures, with a significant increase in versican mRNA in cultures derived from photoaged skin, whereas decorin mRNA levels were significantly decreased in photoaged skin.
Conclusions: This study provides further evidence for the close association of versican with elastic fibers and decorin with collagen fibers, even in the situation of abnormal fiber deposition occurring in photodamaged skin. In addition, changes in versican and decorin immunostaining are accompanied by similar alterations in gene expression.