Inhibition of TGF-beta signaling exacerbates early cardiac dysfunction but prevents late remodeling after infarction.
OBJECTIVE
Transforming growth factor (TGF)-beta promotes the deposition of extracellular matrix protein and also acts as an anti-inflammatory cytokine. These biological effects might be involved in the development and progression of left ventricular (LV) remodeling and failure after myocardial infarction (MI). However, its pathophysiological significance remains obscure in post-MI hearts.


METHODS
Anterior MI was produced in mice by ligating the left coronary artery. TGF-beta mRNA levels increased in both infarcted and noninfarcted LV after MI. To block TGF-beta signaling during the early phase of MI, an extracellular domain of TGF-beta type II receptor (TbetaIIR) plasmid was transfected into the limb skeletal muscles 7 days before ligation.


RESULTS
TbetaIIR increased the mortality during 24 h of MI, as well as exacerbated LV dilatation and contractile dysfunction, the infiltration of neutrophils, and gene expression of tumor necrosis factor-alpha, interleukin-1beta, and monocyte chemoattractant protein-1 compared with nontreated MI mice despite the comparable infarct size. Next, to block TGF-beta signaling during the later phase, TbetaIIR was transfected into mice at days 0 and 7 after ligation. At 4 weeks, LV dilatation and contractile dysfunction in association with myocyte hypertrophy and interstitial fibrosis of noninfarcted LV seen in MI mice were prevented by TbetaIIR.


CONCLUSIONS
The activation of TGF-beta is protective against ischemic myocardial damage during the early phase. However, the beneficial effects might be lost, when its expression is sustained, thereby leading to LV remodeling and failure after MI.
Ikeuchi
Masaki
M
Department of Cardiovascular Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi, Fukuoka 812-8582, Japan.
Tsutsui
Hiroyuki
H
Shiomi
Tetsuya
T
Matsusaka
Hidenori
H
Matsushima
Shouji
S
Wen
Jing
J
Kubota
Toru
T
Takeshita
Akira
A
D000818:Animals; D018932:Chemokine CCL2 / Q000235:genetics; D004452:Echocardiography; D015870:Gene Expression; D007375:Interleukin-1 / Q000235:genetics; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009203:Myocardial Infarction / Q000378:metabolism* / Q000401:mortality / Q000473:pathology; D009206:Myocardium / Q000276:immunology / Q000473:pathology; D020556:Neutrophil Infiltration; D017346:Protein Serine-Threonine Kinases; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta / Q000235:genetics*; D015398:Signal Transduction; D013997:Time Factors; D014162:Transfection / Q000379:methods; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D020257:Ventricular Remodeling
C491768:Ccl2 protein, mouse; D018932:Chemokine CCL2; D007375:Interleukin-1; D018125:Receptors, Transforming Growth Factor beta; D016212:Transforming Growth Factor beta; D017346:Protein Serine-Threonine Kinases; D000077294:Receptor, Transforming Growth Factor-beta Type II