Expression of type XVI collagen in human skin fibroblasts: Enhanced expression in fibrotic skin diseases

Abundance of type XVI collagen mRNA in normal human dermal fibroblasts expl anted from different horizontal layers was determined using RNase protectio n assays. Type XVI collagen mRNA level in the fibroblasts explanted from th e upper dermis was greater than those of the middle and lower dermis. The a ntibody raised against the synthetic N-terminal noncollagenous region react ed with approximate to 210 kDa collagenous polypeptide in the culture mediu m of fibroblasts. Immunohistochemical study of normal human skin demonstrat ed that the antibody reacted preferentially with the fibroblasts and the ex tracellular matrix in the upper dermis rather than those in the middle and lower dermis. Type XVI collagen mRNA level was elevated 2.3-fold in localiz ed scleroderma and 3.6-fold in systemic scleroderma compared with keloid an d normal controls. Immunofluorescent study revealed that an intense immunor eactivity with the antibody was observed in the upper to lower dermal matri x and fibroblasts in the skin of systemic scleroderma as compared with norm al skin. The results suggest that expression of type XVI collagen, a member of fibril-associated collagens with interrupted triple helices, in human s kin fibroblasts can be heterogeneous in the dermal layers and can be modula ted by some fibrotic diseases.