Immunohistochemical studies on proteoglycan expression in normal skin and chronic ulcers

Proteoglycans (PGs) represent a large family of complex molecules. They are found either as integral membrane components or constituents of the extracellular matrix. Their protein backbones are linked to different glycosaminoglycans, such as dermatan-, chondroitin-, keratan- or heparan sulphate. The molecules have specific functions during developmental processes as well as in diseases, such as cancer and inflammation.

The expression patterns of various cell-associated heparan and chondroitin/dermatan-sulphate PGs in human skin and chronic venous ulcers were investigated.

Tissue sections from 11 patients with chronic venous ulcers were used in this study. Monoclonal antibodies were used for detection of the proteoglycans syndecan-1, -2 and -4, glypican, CD44 and perlecan.

The different PGs exhibited individual staining patterns. Syndecan-1 and -4 and glypican expression in chronic ulcers differed from the staining in normal skin. Whereas the expression of syndecan-4 and glypican in intact skin was mostly in the pericellular regions of keratinocytes, the epidermal cells from the wound edge contained mostly intracellular PGs. In the wound edge, syndecan-4 was predominantly expressed by epidermal basal layer cells. Syndecan-1 was less expressed at the epidermal wound margins. PGs bind growth factors, regulate proteolytic activity and act as matrix receptors.

The altered expression patterns of glypican and syndecan-1 and -4 in chronic ulcers reflect their possible roles during inflammation and cell proliferation. Hence, analysis of PG expression should be of interest in future studies on normal as well as defective wound healing.