Involvement of αvβ5 integrin–mediated activation of latent transforming growth factor β1 in autocrine transforming growth factor β signaling in systemic sclerosis fibroblasts
Article first published online: 2 SEP 2005
Copyright © 2005 by the American College of Rheumatology
Arthritis & Rheumatism
Volume 52, Issue 9, pages 2897–2905, September 2005
How to Cite
Asano, Y., Ihn, H., Yamane, K., Jinnin, M., Mimura, Y. and Tamaki, K. (2005), Involvement of αvβ5 integrin–mediated activation of latent transforming growth factor β1 in autocrine transforming growth factor β signaling in systemic sclerosis fibroblasts. Arthritis & Rheumatism, 52: 2897–2905. doi: 10.1002/art.21246
- Issue published online: 2 SEP 2005
- Article first published online: 2 SEP 2005
- Manuscript Accepted: 24 MAY 2005
- Manuscript Received: 24 FEB 2005
- Japanese Ministry of Education. Grant Number: 10770391
- Japanese Ministry of Health and Welfare
To confirm the involvement of αvβ5 in the self-activation system in systemic sclerosis (SSc) fibroblasts.
Levels of αvβ5 expression were analyzed by immunoprecipitation. The promoter activity of the human α2(I) collagen gene was determined by transient transfection assay. Phosphorylation levels and DNA binding ability of Smad3 were investigated by immunoprecipitation and DNA affinity precipitation, respectively. The localization of active transforming growth factor β (TGFβ) was determined by coculture assay using TMLC cells (mink lung epithelial reporter cells that stably express a portion of the plasminogen activator inhibitor 1 promoter). The morphologic features of cells were determined by immunofluorescence analysis.
Levels of αvβ5 expression were significantly elevated in SSc fibroblasts compared with normal fibroblasts. Treatment with anti-αvβ5 antibody or β5 antisense oligonucleotide significantly reduced human α2(I) collagen gene promoter activity in SSc fibroblasts. In SSc fibroblasts pretreated with TGFβ1 antisense oligonucleotide, the exogenous latent TGFβ1 stimulation significantly increased human α2(I) collagen gene promoter activity; this effect was significantly reduced in the presence of anti-αvβ5 antibody. Phosphorylation levels and DNA binding ability of Smad3 in SSc fibroblasts were significantly reduced by treatment with β5 antisense oligonucleotide. The luciferase activity of TMLC cells cocultured with SSc fibroblasts was significantly elevated compared with that of TMLC cells cocultured with normal fibroblasts and was significantly reduced in the presence of anti-αvβ5 antibody. Anti-αvβ5 antibody reversed the myofibroblastic features of SSc fibroblasts.
Up-regulated expression of αvβ5 contributes to the establishment of autocrine TGFβ signaling in SSc fibroblasts through activation of endogenous latent TGFβ1.