Blockade of endogenous transforming growth factor beta signaling prevents up-regulated collagen synthesis in scleroderma fibroblasts: association with increased expression of transforming growth factor beta receptors.

OBJECTIVE: To elucidate the role of transforming growth factor beta (TGFbeta) in the increased expression of the collagen gene in scleroderma fibroblasts.
METHODS: Dermal fibroblasts from 10 patients with diffuse systemic sclerosis (SSc) of recent onset and from 10 healthy individuals were studied. The production of active and total (active + latent) TGFbeta1 levels from cultured dermal fibroblasts was measured using a TGFbeta1 enzyme-linked immunosorbent assay system. Expression of the TGFbeta type I and type II receptor proteins in dermal fibroblasts was determined by immunoblotting, and the level of expression of human alpha2(I) collagen messenger RNA (mRNA) was evaluated by Northern blot analysis. The transcriptional activity of the human alpha2(I) collagen gene was examined with chloramphenicol acetyltransferase (CAT) assays using the -772 COL1A2/CAT construct.
RESULTS: SSc fibroblasts expressed increased levels of TGFbeta type I and type II receptors but secreted amounts of TGFbeta similar to those secreted by normal fibroblasts. The blockade of TGFbeta signaling with anti-TGFbeta antibodies or a TGFbeta1 antisense oligonucleotide abolished the increased mRNA expression, as well as the up-regulated transcriptional activity of the human alpha2(I) collagen gene in SSc fibroblasts.
CONCLUSION: These results suggest that TGFbeta plays a crucial role in the pathogenesis of SSc and raise the possibility of a therapeutic approach with anti-TGFbeta antibodies or a TGF11 antisense oligonucleotide.