Minocycline does not alter collagen type I metabolism of dermal fibroblasts in culture

Abstract.

Minocycline has been used successfully for the treatment of dermal fibrosis in patients suffering from systemic sclerosis. However, little is known of the mechanism of the antifibrotic action of minocycline. We studied the in vitro effects of minocycline by analysing the influence of various amounts of minocycline on cell proliferation and synthesis and degradation of collagen I in cultured human dermal fibroblasts from healthy donors and two patients with systemic sclerosis. Collagen I metabolism of cultured dermal fibroblasts from two- and three-dimensional culture systems was studied by Northern hybridization and real-time RT-PCR. Messenger RNA of collagen I, proline-4-hydroxylase, lysyl-hydroxylase, matrix metalloproteinase I, and protein of MMP-1 (ELISA) and collagen I in culture supernatants were determined. Minocycline did not alter the expression of the investigated mRNAs, irrespective of the dosage, the culture system and the incubation times used. Similarly, the amounts of collagen I and MMP-1 protein were not affected. Consequently, direct antifibrotic effects of minocycline on untreated human dermal fibroblasts in vitro seem unlikely. Therefore, other mechanisms are probably responsible for the clinical effect observed in the treatment of systemic sclerosis.