Demonstration of increased levels of type I collagen mRNA using quantitative polymerase chain reaction in fibrotic and granulomatous skin diseases.

Collagen changes occur in localized scleroderma, scleredema and sarcoidosis. Previous biochemical, immunohistochemical and in situ hybridization studies have revealed increased collagen synthesis in these diseases. In the present study, we measured by pro alpha 1 (I) collagen and beta-actin mRNA levels in skin punch biopsy specimens from lesional and healthy skin using a quantitative polymerase chain reaction (PCR). In this method, the targeted mRNA and a synthetic RNA as a internal standard are co-amplified together with the same primers. The amount of pro alpha 1 (I) collagen mRNA in cutaneous sarcoidosis lesions was found to be increased about two- to threefold compared with the values obtained for the healthy skin of the same two patients. In lesional skin of three patients with localized scleroderma the number of pro alpha 1 (I) collagen molecules was increased about two-fold. The beta-actin mRNA values were at the same level in the affected and unaffected skin of all the patients studied. In conclusion, a marked increase in type I collagen gene expression was seen in localized scleroderma and scleredema, leading to fibrosis of the skin, and in a granulomatous skin disease, cutaneous sarcoidosis.