Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


The Triterpenoid CDDO Abrogates Canonical TGF-beta Signaling and Fibrotic Responses in Normal and Scleroderma Fibroblasts by Stabilizing the Anti-Oxidant Nuclear Factor-Like 2 (Nrf2).

Komura2,  Kazuhiro, Wei2,  Jun, Lord2,  Gabriel, Varga1,  John

Northwestern Univ Feinberg School, Chicago, IL
Northwestern University Feinberg School of Medicine

Background:

Scleroderma is characterized by excessive collagen accumulation and fibrosis in multiple organs. TGF-b stimulates collagen synthesis and is implicated in the pathogenesis of fibrosis. 2-Cyano-3,12-Dioxooleana-1,9-Dien-617-Oic acid (CDDO) is a synthetic triterpenoid that is known to activate peroxisome proliferator activated receptor (PPAR)-g. We previously demonstrated that PPAR-g ligands abrogated the stimulation of collagen synthesis induced by TGF-b in fibroblasts, by disrupting canonical TGF-b signaling in a PPAR-g dependent manner. The objective of the current study is to address the anti-fibrotic effect of CDDO in fibroblasts.

Methods:

The mesenchymal progenitor 3T3-L1 cell line was incubated with CDDO to induce adipogenesis. Expression of adipogenic markers was examined by real-time qPCR and immunofluorescence. Modulation of PPAR-g promoter activity was examined in foreskin fibroblasts incubated with CDDO. Induction of profibrotic gene expression by TGF-b was evaluated by real-time qPCR and Western analysis. PPAR-g dependence was evaluated using GW9662 a PPAR-g antagonist. Nrf2 expression and activity were examined by Western blot, immunofluorescence and antioxidant response element (ARE) reporter assays. Effects of Nrf2 on canonical TGF-b signaling were examined by transient transfection in foreskin fibroblasts. Skin fibroblasts from 6 patients with diffuse cutaneous SSc were incubated with CDDO and profibrotic gene levels were measured by real-time PCR and Western analysis.

Results:

CDDO induced a marked adipogenic response in 3T3-L1 cells. Moreover, CDDO significantly enhances PPAR-g transcriptional activity. CDDO abrogated TGF-binduced stimulation of collagen and a-smooth muscle actin (a-SMA) expression in a dose-dependent manner, and abrogated the stimulation of Smad2/3-mediated transcriptional activity induced by TGF-b. These inhibitory effects were PPAR-g–independent. CDDO also caused a marked accumulation and nuclear localization of Nrf2. Moreover CDDO stimulated Nrf2-dependent transcriptional activity. Ectopic Nrf2 was sufficient by itself to abrogate TGF-b stimulation of Smad-dependent transcription. In scleroderma fibroblasts, CDDO caused significant suppression of collagen gene expression at mRNA and protein levels, and attenuated the myofibroblast phenotype of these cells.

Conclusion:

The triterpenoid and novel PPAR-g ligand CDDO abrogates canonical TGF-b signaling and suppresses fibrotic responses in a PPAR-g-independent manner. Nrf2, a master regulator of the antioxidant response, is activated by CDDO in normal fibroblasts, and appears to mediate the CDDO inhibitory process. Nrf2 thus is a novel target for anti-fibrotic therapy, and pharmacological modulation of the Nrf2 expression or activity might have a therapeutic potential in scleroderma.

To cite this abstract, please use the following information:
Komura, Kazuhiro, Wei, Jun, Lord, Gabriel, Varga, John; The Triterpenoid CDDO Abrogates Canonical TGF-beta Signaling and Fibrotic Responses in Normal and Scleroderma Fibroblasts by Stabilizing the Anti-Oxidant Nuclear Factor-Like 2 (Nrf2). [abstract]. Arthritis Rheum 2010;62 Suppl 10 :617
DOI: 10.1002/art.28385

Abstract Supplement

Meeting Menu

2010 ACR/ARHP