Increased expression of tenascin in the dermis in scleroderma

The expression of tenascin, a recently discovered extracellular matrix protein, was studied by immunohistochemical techniques in scleroderma skin and compared with its distribution in normal skin. In progressive systemic sclerosis, a marked increase in tenascin content was observed in the superficial reticular dermis. In localized scleroderma, the deposition of tenascin was increased both in the superficial and deep dermis of involved skin, whereas in clinically uninvolved skin the distribution of tenascin was the same as in normal control skin, i.e. the papillary dermis and peri-appendiceal zone. The distribution of tenascin did not strictly parallel that of fibronectin. These findings and the current knowledge of tenascin biology suggest that the overproduction of tenascin in scleroderma dermis could be secondary to stimulation of fibroblasts by immune cell-derived cytokines, or could be due to abnormal fibroblasts, or a subpopulation of fibroblasts, producing high levels of this extracellular matrix protein.