Anoxia-reoxygenation stimulates collagen type-I and MMP-1 expression in cardiac fibroblasts: modulation by the PPAR-gamma ligand pioglitazone.
BACKGROUND
Cardiac remodeling after ischemic injury is a major cause of heart failure. In this process, fibroblast growth and collagen synthesis and degradation play a critical role. Recent studies indicate that ligands of the peroxisome proliferator-activated receptors-gamma (PPAR-gamma) alter cardiac remodeling during chronic ischemia. This study was designed to investigate if the PPAR-gamma ligand pioglitazone would modulate fibroblast growth and collagen type-I synthesis (and expression) in cardiac fibroblasts exposed to anoxia-reoxygenation (A-R).


RESULTS
Cardiac fibroblasts were exposed to anoxia (95% N2/5% CO2) and then reoxygenation (95% air/5% CO2). A-R increased fibroblast growth (MTT assay) as well as collagen type-I synthesis (H-proline incorporation) and protein expression (Western analysis). Concurrently, there was a parallel increase in the expression of matrix metalloproteinase-1 (MMP-1) in fibroblasts. Pretreatment of cardiac fibroblasts with pioglitazone (10 M) reduced all these effects of A-R. Further, A-R stimulated intracellular reactive oxygen species (ROS) generation and activated the redox-sensitive transcription factor NF-kappaB (both P < 0.05). Both these phenomena were inhibited by pretreatment of cells with pioglitazone.


CONCLUSIONS
Thus, it appears that A-R stimulates fibroblast cell growth, collagen type-I synthesis, and MMP-1 expression in cardiac fibroblasts, most likely a result of ROS generation. Inhibition of ROS generation and induction of NF-kappaB in cardiac fibroblasts during A-R may be a mechanism of action of pioglitazone.
Chen
Kui
K
Department of Internal Medicine, University of Arkansas for Medical Sciences and Central Arkansas Veterans Healthcare System, Little Rock, Arkansas 72205, USA.
Li
Dayuan
D
Zhang
Xingjian
X
Hermonat
Paul L
PL
Mehta
Jawahar L
JL
D000818:Animals; D015153:Blotting, Western; D024042:Collagen Type I / Q000096:biosynthesis*; D024202:Electrophoretic Mobility Shift Assay; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism*; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D000860:Hypoxia / Q000378:metabolism*; D008297:Male; D020781:Matrix Metalloproteinase 1 / Q000096:biosynthesis*; D016328:NF-kappa B / Q000378:metabolism; D010100:Oxygen / Q000494:pharmacology*; D047495:PPAR gamma / Q000187:drug effects*; D000077205:Pioglitazone; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D045162:Thiazolidinediones / Q000494:pharmacology*; D018808:Transcription Factor AP-1 / Q000378:metabolism
D024042:Collagen Type I; D007004:Hypoglycemic Agents; D016328:NF-kappa B; D047495:PPAR gamma; D017382:Reactive Oxygen Species; D045162:Thiazolidinediones; D018808:Transcription Factor AP-1; D020781:Matrix Metalloproteinase 1; D010100:Oxygen; D000077205:Pioglitazone