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
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.
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.
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-gindependent. 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.
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