DOI: 10.1161/circ.148.suppl_1.14924 ISSN: 0009-7322

Abstract 14924: SM22-Cre-Mediated SOCS3 Deficient Mice Exhibit Pericardial Fibrosis, Diastolic Dysfunction, and Increased Mortality Rates Due to Augmented Activation of STAT3 in Fibroblasts

Toshiyuki Yanai, Mai Yamamoto, Hideo Yasukawa, Kodai Shibao, Daiki Akagaki, Kota Okabe, Tatsuhiro Shibata, Shoichiro Nohara, Jinya Takahashi, Tomoko Sasaki, Kanako Shima, Yoshihiro Fukumoto
  • Physiology (medical)
  • Cardiology and Cardiovascular Medicine

Background: Suppressor of cytokine signaling-3 (SOCS3) is a cytokine-inducible potent negative regulator of STAT3 signaling pathway. Here, we aimed to determine whether SOCS3 in non-cardiomyocytes would play a role in cardiovascular pathophysiology.

Methods and Results: To investigate the role of SOCS3 in non-cardiomyocytes, we generated conditional knockout mice by crossing SOCS3-flox mice with SM22-α-Cre mice (SM22-SOCS3-KO mice). Mortality rates in the SM22-SOCS3-KO mice was significantly higher than that in the wild-type mice (WT). Heart weight to body weight ratio was significantly increased in SM22-SOCS3-KO mice compared with WT at 12 months of age. Echocardiographic analyses revealed that SM22-SOCS3-KO mice showed significantly increased left ventricular diastolic dysfunction compared with WT from 12 months of age. Sirius-red staining revealed that thickness of pericardium and cardiac interstitial fibrosis in SM22-SOCS3-KO mice were markedly greater compared with WT mice at 12 months of age. Western blot analyses showed that phosphorylated STAT3 was significantly increased in SM22-SOCS3-KO hearts compared with WT mice at 12 months of age. PCR array analysis revealed that the expression of pro-fibrotic ctgf , pdgf , and TGF-beta family genes including tgf-beta1 , tgf-beta2 , and tgf-beta3 , were significantly higher in SM22-SOCS3-KO hearts than those in WT at 6 months of age. We also found that circulating interleukin-6 concentration was significantly higher in SM22-SOCS3-KO mice compared with WT mice at 12 months of age. After interleukin-6 administration, in the heart tissue from SM22-SOCS3-KO mice, coimmunostaining of phosphorylated STAT3 and ER-TR7 revealed that STAT3 activation occurred in fibroblasts in the coronary arterial adventitia and pericardium.

Conclusion: Thus, SM22-Cre-mediated SOCS3 deletion induces higher mortality rates, increased pericardial fibrosis, cardiac interstitial fibrosis, and increased diastolic dysfunction in aging mice, possibly through the increased activation of STAT3 in fibroblasts.

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