Session Information
Title: Systemic Sclerosis, Fibrosing Syndromes and Raynaud's - Pathogenesis, Animal Models and Genetics
Session Type: Abstract Submissions (ACR)
Background/Purpose
Systemic sclerosis (SSc) is an autoimmune connective tissue disorder characterized by excess collagen deposition, vascular changes and production of autoantibodies that affects multiple organs. Transforming growth factorβ1 (TGF-β1), that promotes collagen synthesis, extracellular matrix (ECM) remodeling and myofibroblast differentiation, is thought to play a key role in the pathogenesis of SSc. The vasoconstrictive peptide endothelin-1 (ET-1) is also known as potent fibrotic factors. ET-1 binds to two distinct subtype of G protein coupled receptors, ET receptor A (ETRA) and ET receptor B (ETRB). The fibrotic functions of each ET receptor remain unclear partly because the distribution and expression of ET receptors differs according to the disease situations, the respective organs or the cell types. The aim of our study was to examine the effects of TGF-β1 on the fibrogenic phenotype of SSc skin fibroblasts through ET-1 production and to clarify how the signal transduction through TGF-β1 is associated with upregulation of ET-1.
Methods
Human SSc skin fibroblasts (SSc fibroblasts) were obtained from 5 SSc patients. Recombinant TGF-β1, recombinant ET-1, SIS3 as an inhibitor of Smad3 phosphorylation, SP600125 as an inhibitor of c-JUN N-terminal kinase (JNK), BQ123 as a selective ETRA antagonist, BQ788 as a selective ETRB antagonist and bosentan as a dual ETRA/ETRB receptor antagonist were used in this study. SSc fibroblasts were incubated with TGF-β1 in the presence of SIS3 or SP600125. In addition, the effects of BQ123, BQ788 or bosentan were explored. The expression of ET-1, CTGF and type Ⅰ collagen was evaluated using ELISA and real time RT-PCR. ETRA and ETRB expressions were assessed by immunohistochemistry and fluorescence activated cell sorting (FACS) analysis.
Results
Both ETRA and ETRB were expressed in SSc fibroblasts as detected by immunohistochemistry. TGF-β1 increased ET-1 in the levels of mRNA and protein and this increase in ET-1 was suppressed by either SIS3 or SP600125. Upregulation of COL1A1 and CTGF by TGF-β1 were reduced by either ETRA or ETRB antagonist, and the effects were enhanced by dual ETRA/ETRB antagonist.
Conclusion
We herein revealed that TGF-β1 produced ET-1 through both Smad and JNK cascade and dual ETRA/ETRB antagonist contributed to diminishing COL1A1 and CTGF mRNA in fibroblasts. These findings suggest that the fibrogenic effects by TGF-b1 may in part be explained by the autocrine stimulation of ET-1. The dual ETRA/ETRB might be a novel therapeutic strategy for the SSc skin fibrosis.
Disclosure:
T. Higuchi,
None;
Y. Kawaguchi,
None;
A. Tochimoto,
None;
Y. Ota,
None;
Y. Katsumata,
None;
T. Gono,
None;
M. Hanaoka,
None;
Y. Okamoto,
None;
H. Kawasumi,
None;
H. Yamanaka,
None.
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/endothelin-1-is-a-downstream-mediator-of-profibrotic-effects-by-transforming-growth-factor-%ce%b21-in-systemic-sclerosis-skin-fibroblasts/