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 explanted from different horizontal layers was determined using RNase protection assays. Type XVI collagen mRNA level in the fibroblasts explanted from the upper dermis was greater than those of the middle and lower dermis. The antibody raised against the synthetic N-terminal noncollagenous region reacted with approximate to 210 kDa collagenous polypeptide in the culture medium of fibroblasts. Immunohistochemical study of normal human skin demonstrated that the antibody reacted preferentially with the fibroblasts and the extracellular 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 localized scleroderma and 3.6-fold in systemic scleroderma compared with keloid and normal controls. Immunofluorescent study revealed that an intense immunoreactivity with the antibody was observed in the upper to lower dermal matrix and fibroblasts in the skin of systemic scleroderma as compared with normal skin. The results suggest that expression of type XVI collagen, a member of fibril-associated collagens with interrupted triple helices, in human skin fibroblasts can be heterogeneous in the dermal layers and can be modulated by some fibrotic diseases.