Electrophilic peroxisome proliferator-activated receptor-gamma ligands have potent antifibrotic effects in human lung fibroblasts.
Pulmonary fibrosis is a progressive scarring disease with no effective treatment. Transforming growth factor (TGF)-beta is up-regulated in fibrotic diseases, where it stimulates differentiation of fibroblasts to myofibroblasts and production of excess extracellular matrix. Peroxisome proliferator-activated receptor (PPAR) gamma is a transcription factor that regulates adipogenesis, insulin sensitization, and inflammation. We report here that a novel PPARgamma ligand, 2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid (CDDO), is a potent inhibitor of TGF-beta-stimulated differentiation of human lung fibroblasts to myofibroblasts, and suppresses up-regulation of alpha-smooth muscle actin, fibronectin, collagen, and the novel myofibroblast marker, calponin. The inhibitory concentration causing a 50% decrease in aSMA for CDDO was 20-fold lower than the endogenous PPARgamma ligand, 15-deoxy-Delta(12,14)-prostaglandin J(2) (15 d-PGJ(2)), and 400-fold lower than the synthetic ligand, rosiglitazone. Pharmacologic and genetic approaches were used to demonstrate that CDDO mediates its activity via a PPARgamma-independent pathway. CDDO and 15 d-PGJ(2) contain an alpha/beta unsaturated ketone, which acts as an electrophilic center that can form covalent bonds with cellular proteins. Prostaglandin A(1) and diphenyl diselenide, both strong electrophiles, also inhibit myofibroblast differentiation, but a structural analog of 15 d-PGJ(2) lacking the electrophilic center is much less potent. CDDO does not alter TGF-beta-induced Smad or AP-1 signaling, but does inhibit acetylation of CREB binding protein/p300, a critical coactivator in the transcriptional regulation of TGF-beta-responsive genes. Overall, these data indicate that certain PPARgamma ligands, and other small molecules with electrophilic centers, are potent inhibitors of critical TGF-beta-mediated profibrogenic activities through pathways independent of PPARgamma. As the inhibitory concentration causing a 50% decrease in aSMA for CDDO is 400-fold lower than that in rosiglitazone, the translational potential of CDDO for treatment of fibrotic diseases is high.
Ferguson
Heather E
HE
Department of Environmental Medicine, University of Rochester, Rochester, NY 14642, USA.
Kulkarni
Ajit
A
Lehmann
Geniece M
GM
Garcia-Bates
Tatiana M
TM
Thatcher
Thomas H
TH
Huxlin
Krystel R
KR
Phipps
Richard P
RP
Sime
Patricia J
PJ
D000107:Acetylation; D000199:Actins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D017931:DNA Primers / Q000235:genetics; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D008024:Ligands; D008168:Lung / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D009828:Oleanolic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D047495:PPAR gamma / Q000819:agonists* / Q000378:metabolism; D015230:Prostaglandin D2 / Q000031:analogs & derivatives / Q000494:pharmacology; D011658:Pulmonary Fibrosis / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D000077154:Rosiglitazone; D015398:Signal Transduction / Q000187:drug effects; D051785:Smad Proteins / Q000378:metabolism; D045162:Thiazolidinediones / Q000494:pharmacology; D018808:Transcription Factor AP-1 / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism; D050880:p300-CBP Transcription Factors / Q000378:metabolism
C097240:15-deoxy-delta(12,14)-prostaglandin J2; C116817:2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid; C541116:ACTA2 protein, human; D000199:Actins; D017931:DNA Primers; D008024:Ligands; D047495:PPAR gamma; D051785:Smad Proteins; D045162:Thiazolidinediones; D018808:Transcription Factor AP-1; D016212:Transforming Growth Factor beta; D000077154:Rosiglitazone; D009828:Oleanolic Acid; D050880:p300-CBP Transcription Factors; D015230:Prostaglandin D2