Differential expression of tenascin in the skin during hapten-induced dermatitis.

Tenascin is a large extracellular matrix glycoprotein which is found in limited regions of normal adult tissues including the skin. We investigated the induction of tenascin expression in mouse skin during hapten-induced dermatitis. In the dorsal skin, hapten application first induced a transient expression of tenascin in deeper regions of the skin. Its distribution then spread over the whole dermis corresponding to the infiltration of Mac-2-positive macrophages. In the ear, tenascin was consistently found in the subcutaneous tissue on the inner side, but very little was seen on the outer side. Tenascin did appear transiently, however, on both sides under hapten treatment. In the early phase of allergic contact dermatitis, no apparent induction of tenascin expression was observed in the swollen ear. However, there was an abundant tenascin expression on both sides during healing. Tenascin expressed under normal conditions was mostly the 180-kDa isoform, while the 230-kDa isoform was markedly induced during healing of the dermatitis. These results suggest that tenascin, particularly the larger 230-kDa isoform, may play important roles in the pathogenesis and healing of hapten-induced dermatitis.