title: IL-17 induces myocardial fibrosis and enhances RANKL/OPG and MMP/TIMP signaling in isoproterenol-induced heart failure.
abstract: OBJECTIVE
  This study was designed to investigate whether IL-17 can regulate the expression of the MMP/TIMP system, the OPG/RANK/RANKL system, or type-I and type-III collagen fibers in a rat model of isoproterenol-induced heart failure (HF). We also investigated the effect of IL-17 on myocardial fibrosis in this model.
  
  
  METHODS
  HF was induced in Wistar-Kyoto rats by hypodermic injection of isoproterenol (ISO) twice every 24 h. After 2 months, the surviving rats were divided into three groups: monoclonal Anti-IL-17 Ab (100 microg/day), IgG (100 microg/day) or PBS were injected five times every 48 h (i.p.). One day after the last injection, all of the rats were sacrificed. H&E and Masson staining were used to evaluate myocardial fibrosis, and immunohistochemistry was used to measure the levels of MMP-1, TIMP-1, TIMP-4, OPG, RANKL, type-I and type-III collagen fibers. We also treated adult rat cardiac fibroblasts with IL-17 (10 ng/ml), IL-17 (10 ng/ml)+OPG (10 ng/ml), IL-17 (10 ng/ml)+anti-RANKL Ab (100 ng/ml), or PBS for 24 h, realtime RT-PCR was used to measure the expressions of MMP-1.
  
  
  RESULTS
  The expressions of MMP-1, RANKL, and type-I and -III collagen fibers decreased, and the expressions of TIMP-1, TIMP-4, and OPG increased in the Anti-IL-17 group compared to controls. H&E and Masson staining revealed that blockade of IL-17 can improve myocardial fibrosis in HF. IL-17 increased the expression of MMP-1 in cardiac fibroblasts, and OPG and anti-IL-17 Ab could inhibit this function partly. Thus, IL-17 was dependent on the RANKL/OPG system to induce MMP-1 partly.
  
  
  CONCLUSIONS
  Our study demonstrates the contribution of IL-17 to myocardial fibrosis in isoproterenol-induced HF. IL-17 can regulate the RANKL/OPG and MMP/TIMP systems in this model. The RANKL/OPG system is one of intermediaries between IL-17 and MMP-1 in cardiac fibroblasts. As a harmful cytokine, anti-IL-17 treatment is a potential therapeutic strategy in HF.
authors.affiliation: Department of Cardiology, theFirst Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang, China.
authors.forename: Weiwei
authors.initials: W
authors.lastname: Feng
authors.forename: Weimin
authors.initials: W
authors.lastname: Li
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.forename: Fang
authors.initials: F
authors.lastname: Wang
authors.forename: Yue
authors.initials: Y
authors.lastname: Li
authors.forename: Wei
authors.initials: W
authors.lastname: Yan
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D005355:Fibrosis; D006333:Heart Failure / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology*; D020381:Interleukin-17 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D020782:Matrix Metalloproteinases / Q000378:metabolism*; D009206:Myocardium / Q000473:pathology*; D053244:Osteoprotegerin / Q000378:metabolism*; D053245:RANK Ligand / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction; D019714:Tissue Inhibitor of Metalloproteinases / Q000378:metabolism
chemical_list: D020381:Interleukin-17; D053244:Osteoprotegerin; D053245:RANK Ligand; D019714:Tissue Inhibitor of Metalloproteinases; C506032:Tnfrsf11b protein, rat; D020782:Matrix Metalloproteinases; D007545:Isoproterenol