title: Extracellular HSP60 induces inflammation through activating and up-regulating TLRs in cardiomyocytes.
abstract: OBJECTIVE
  The molecular events leading from cardiomyocyte ischaemia to inflammatory cytokine production are not well understood. We previously found that heat shock protein 60 (HSP60) appeared in extracellular space after cardiomyocyte ischaemia. This study examined the activation and regulation of toll-like receptors (TLRs) by HSP60 in cardiomyocytes.
  
  
  RESULTS
  Cytokine production and TLRs regulation mediated by TLRs signalling were examined in response to exogenous HSP60 (exHSP60) and endogenous HSP60 (enHSP60) released extracellularly under ischaemia. The results showed that exHSP60 induced inflammatory cytokine production in adult rat cardiomyocytes and H9c2 cells (a standard cardiac cell line derived from embryonic cells), through a pathway dependent on TLR4, myeloid differentiation factor 88 (MyD88), p38, and nuclear factor-κB (NF-κB). Further study revealed up-regulated expression of both TLR2 and TLR4 by exHSP60, which was dependent on the activation of TLR4, MyD88, c-Jun NH2-terminal kinase (JNK), and NF-κB, but not on p38. In myocytes exposed to ischaemia, enHSP60 was released into the media, and triggered cytokine production and TLR2/4 overexpression, through the same pathways as exHSP60. In rats subjected to LAD ligation, the released enHSP60 contributed to cytokine production and TLR2/4 overexpression in the ischaemic myocardium.
  
  
  CONCLUSIONS
  Extracellular HSP60 induces cytokine production via TLR4-MyD88-p38/NF-κB pathway, and up-regulates TLR2/4 expression via TLR4-MyD88-JNK/NF-κB pathway. Both pathways contribute to myocardial inflammation induced by ischaemia.
authors: Department of Physiology and the Key Laboratory of Molecular Neurobiology of Ministry of Education, Second Military Medical University, 800 Xiangyin Road, Shanghai 200433, PR China.
authors: Jing
authors: J
authors: Tian
authors: Xin
authors: X
authors: Guo
authors: Xue-Mei
authors: XM
authors: Liu
authors: Li
authors: L
authors: Liu
authors: Qi-Fang
authors: QF
authors: Weng
authors: Shu-Juan
authors: SJ
authors: Dong
authors: Anne A
authors: AA
authors: Knowlton
authors: Wen-Jun
authors: WJ
authors: Yuan
authors: Li
authors: L
authors: Lin
mesh_terms: D000818:Animals; D002460:Cell Line; D018834:Chaperonin 60 / Q000378:metabolism*; D004195:Disease Models, Animal; D007249:Inflammation / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D018836:Inflammation Mediators / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D008297:Male; D024101:Mitochondrial Proteins / Q000378:metabolism*; D053594:Myeloid Differentiation Factor 88 / Q000378:metabolism; D017202:Myocardial Ischemia / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000276:immunology / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D034622:RNA Interference; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D013997:Time Factors; D051195:Toll-Like Receptor 2 / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000378:metabolism; D051193:Toll-Like Receptors / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D015854:Up-Regulation; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D018834:Chaperonin 60; C557067:Hspd1 protein, rat; D018836:Inflammation Mediators; D015850:Interleukin-6; D024101:Mitochondrial Proteins; C507781:Myd88 protein, rat; D053594:Myeloid Differentiation Factor 88; D016328:NF-kappa B; C495343:Tlr2 protein, rat; C495347:Tlr4 protein, rat; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D014409:Tumor Necrosis Factor-alpha; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases
keywords: Cardiomyocyte; Heat shock protein; Inflammatory cytokine; Toll-like receptor