Transforming growth factor-beta receptor antagonism attenuates myocardial fibrosis in mice with cardiac-restricted overexpression of tumor necrosis factor - PubMed (original) (raw)

Comparative Study

Transforming growth factor-beta receptor antagonism attenuates myocardial fibrosis in mice with cardiac-restricted overexpression of tumor necrosis factor

Yasushi Sakata et al. Basic Res Cardiol. 2008 Jan.

Abstract

The mechanisms that are responsible for the development of myocardial fibrosis in inflammatory cardiomyopathy are unknown. We have previously generated lines of transgenic mice with cardiac-restricted overexpression of tumor necrosis factor (MHCsTNF mice), a pro-inflammatory cytokine. The MHCsTNF mice develop a heart failure phenotype that is characterized by progressive myocardial fibrosis, as well as increased levels transforming growth factor-beta (TGF-beta)(mRNA and protein. In order to determine whether TGF-beta-mediated signaling was responsible for the myocardial fibrosis observed in the MHCsTNF mice, we treated MHCsTNF and littermate control mice from 4 to 12 weeks of age with a novel orally available TGF-beta receptor antagonist (NP-40208). At the time of terminal study, myocardial collagen content was determined using the picrosirius red technique, and left ventricular (LV) systolic and diastolic function were determined using the Langendorff method. Treatment with NP-40208 resulted in a significant (P < 0.05) 65% decrease in nuclear translocation of Smad 2/3, a significant (P < 0.05), decrease in the heart-weight to body-weight ratio from 6.5 to 5.7, a approximately 37% decrease in fibrillar collagen content (P < 0.01) and a significant (P < 0.05) decrease in the LV chamber stiffness by approximately 25% in the MHCsTNF mice when compared to diluent-treated controls. Treatment with NP-40208 had no discernable effect on LV systolic function, nor any effect on cardiac myocyte size or fetal gene expression in the MHCsTNF mice. Taken together, these observations suggest that sustained pro-inflammatory signaling in the adult heart is associated with a pro-fibrotic phenotype that arises, at least in part, from TGF-beta-mediated signaling, with resultant activation of Smad 2/3, leading to increased myocardial fibrosis and increased LV diastolic chamber stiffness.

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Figures

Figure 1

Nuclear and cytoplasmic Smad 2/3 levels in littermate control and MHCsTNF mice. Panel A: Representative Western blots of Smad 2/3 in nuclear and cytoplasmic fractions in diluent treated littermate control, NP-40208 treated littermate control, diluent treated MHCsTNF, and NP-40208 treated MHCsTNF mice. Panel B: Results of group data for Smad 2/3 levels in nuclear and cytoplasmic fractions and the ratio of nuclear to cytoplasmic Smad 2/3 in diluent treated littermate control (n=3 hearts), NP-40208 treated littermate controls (n=3 hearts), diluent MHCsTNF (n = 3 hearts) mice, and NP-40208 treated MHCsTNF (n = 4 hearts) mice. (Key: * p <0.05 vs. diluent and NP-40208 treated littermate controls, † p < 0.05 vs. diluent treated MHCsTNF mice).

Figure 2

Heart-weight to body-weight ratio in diluent treated littermate controls (n=7), NP-4-2–8 treated littermate controls (n=6), diluent treated MHCsTNF (n=6) mice, and NP-40208 treated MHCsTNF (n=6) mice. (Key * p < 0.05 vs. diluent and NP-40208 treated littermate controls, † p < 0.05 vs. diluent treated MHCsTNF mice).

Figure 3

Effect of TβRI antagonism on myocardial fibrillar collagen content in littermate control and MHCsTNF mice. Panel A: Representative picrosirius red staining of myocardial samples from diluent treated littermate control, NP-40208 treated littermate control, diluent treated MHCsTNF, and NP-40208 treated MHCsTNF mice. Panel B: Results of group data for fibrillar collagen content (expressed as percentage of myocardial area) in diluent treated littermate control (n=5), NP-40208 treated littermate control (n=5), diluent treated MHCsTNF (n=8) mice, and NP-40208 treated MHCsTNF (n=7) mice. (Key * p < 0.05 vs. diluent and NP-40208 treated littermate controls, † p < 0.05 vs. diluent treated MHCsTNF mice).

Figure 4

Diastolic pressure volume relationship and LV chamber stiffness in littermate control and MHCsTNF mice. Panel A: Diastolic pressure-volume relationship for littermate control and MHCsTNF mice. Panel B: Results of group data for LV chamber stiffness constant in littermate control (n=10) and MHCsTNF (n=10) mice. (Key: LM = Littermate; * p<0.05 vs. diluent treated littermate controls; † p < 0.05 vs. diluent treated MHCsTNF mice)

Figure 5

Effect of TβIR antagonism on diastolic pressure volume relationship and LV chamber stiffness in littermate control and MHCsTNF mice. Panel A: Diastolic pressure-volume relationship for diluent treated littermate control (n=7 hearts), NP-40208 treated littermate controls (n= 6 hearts), diluent treated MHCsTNF (n=7 hearts), and NP-40208 treated MHCsTNF (n=6 hearts) mice. Panel B: Results of group data for chamber stiffness constant in diluent treated littermate control (n=7 hearts), NP-40208 treated littermate control (n=6), diluent treated MHCsTNF (n=7), and NP-40208 treated MHCsTNF (n=6) hearts. (Key: LM = littermate; *p <0.05 vs. diluent and NP-40208 treated littermate controls, † p < 0.05 vs. diluent treated MHCsTNF mice).

Figure 6

Fetal gene expression in littermate control and MHCsTNF mice. Representative Northern blots for Serca2a, alpha-myosin heavy chain (α-MHC) and beta-myosin heavy chain (β-MHC) in diluent treated littermate control, NP-40208 treated littermate control, diluent treated MHCsTNF mice and NP-40208 treated MHCsTNF mice.

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Transforming growth factor-beta receptor antagonism attenuates myocardial fibrosis in mice with cardiac-restricted overexpression of tumor necrosis factor - PubMed (original) (raw)