title: Hypoxia-stimulated cardiac fibroblast production of IL-6 promotes myocardial fibrosis via the TGF-β1 signaling pathway.
abstract: Interlukin-6 (IL-6) is a multifunctional cytokine produced by several cell types that has a role in fibrosis. Fibroblasts (FBs) maintain this underlying pathogenic change through regulation of IL-6 production; however, its potential functional role in regulating surrounding cellular structural changes during ischemic myocardial remodeling remains unexplored. Here, we generated FBs, cardiomyocytes (CMs), and blood vascular endothelial cells (ECs) from the ventricles of neonatal rats. IL-6 was then overexpressed in FBs and the cells were treated with IL-6 receptor inhibitor (IL6RI), TGF-β1 receptor inhibitor (TβRI), or MMP2/MMP9 inhibitor (MMPI) using monoculture or coculture models under hypoxic conditions. The results indicate that overexpression of IL-6 is sufficient to induce myofibroblastic proliferation, differentiation, and fibrosis, probably via increased TGF-β1-mediated MMP2/MMP3 signaling. The use of IL6RI, TβRI, or MMPI diminished these effects. In addition, IL-6 activated the apoptosis-associated factors Caspase3 and Smad3, and decreased the expression of anti-apoptotic factor Bcl2, resulting in apoptosis of CMs under hypoxic coculture: IL6RI or TβRI inhibited these effects. Unexpectedly, IL-6-overexpressing FBs significantly increased the angiogenesis of ECs, which involved significant increases in the expression of proangiogenic growth factors. Treatment of FBs with IL6RI or TβRI in coculture with ECs reduced the levels of secreted proangiogenic growth factors, and the angiogenesis of ECs was significantly downregulated. Thus, IL-6 functions in ischemic myocardial remodeling through multifunctional reprogramming of hypoxia-associated FBs towards fibrosis via upregulation of the TGF-β1 signaling pathway.
authors.affiliation: Department of Cardiology, Yangpu Hospital, Tongji University School of Medicine, Shanghai, China.
authors.forename: Jia-Hong
authors.initials: JH
authors.lastname: Wang
authors.affiliation: Department of Cardiology, Dahua Hospital, Shanghai, China.
authors.forename: Lan
authors.initials: L
authors.lastname: Zhao
authors.affiliation: Central Experimental Laboratory, Yangpu Hospital, Tongji University School of Medicine, Shanghai, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Pan
authors.affiliation: Department of Cardiology, Yangpu Hospital, Tongji University School of Medicine, Shanghai, China.
authors.forename: Nan-Nan
authors.initials: NN
authors.lastname: Chen
authors.affiliation: Department of Cardiology, Yangpu Hospital, Tongji University School of Medicine, Shanghai, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Chen
authors.affiliation: Department of Cardiology, Yangpu Hospital, Tongji University School of Medicine, Shanghai, China.
authors.forename: Qun-Lin
authors.initials: QL
authors.lastname: Gong
authors.affiliation: Department of Cardiology, Yangpu Hospital, Tongji University School of Medicine, Shanghai, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Su
authors.affiliation: Department of Cardiology, Dahua Hospital, Shanghai, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Yan
authors.affiliation: Department of Cardiology, Dahua Hospital, Shanghai, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Cardiology, Yangpu Hospital, Tongji University School of Medicine, Shanghai, China.
authors.forename: Shao-Heng
authors.initials: SH
authors.lastname: Zhang
mesh_terms: D000818:Animals; D017209:Apoptosis; D049109:Cell Proliferation; D002478:Cells, Cultured; D018920:Coculture Techniques; D042783:Endothelial Cells / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D005347:Fibroblasts / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D005355:Fibrosis; D000860:Hypoxia / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D015850:Interleukin-6 / Q000096:biosynthesis*; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D061965:Matrix Metalloproteinase Inhibitors / Q000494:pharmacology; D008955:Models, Cardiovascular; D009206:Myocardium / Q000276:immunology / Q000378:metabolism* / Q000473:pathology*; D032383:Myocytes, Cardiac / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D058628:Myofibroblasts / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D018919:Neovascularization, Physiologic; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors; D051381:Rats; D000077293:Receptor, Transforming Growth Factor-beta Type I; D019947:Receptors, Interleukin-6 / Q000037:antagonists & inhibitors; D018125:Receptors, Transforming Growth Factor beta / Q000037:antagonists & inhibitors; D015398:Signal Transduction; D053773:Transforming Growth Factor beta1 / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D015850:Interleukin-6; D061965:Matrix Metalloproteinase Inhibitors; D019947:Receptors, Interleukin-6; D018125:Receptors, Transforming Growth Factor beta; C508962:Tgfb1 protein, rat; D053773:Transforming Growth Factor beta1; D017346:Protein Serine-Threonine Kinases; D000077293:Receptor, Transforming Growth Factor-beta Type I; C000625843:Tgfbr1 protein, rat; D020778:Matrix Metalloproteinase 2; C522363:Mmp2 protein, rat; D020780:Matrix Metalloproteinase 9; C572337:Mmp9 protein, rat