title: Human myocardium releases heat shock protein 27 (HSP27) after global ischemia: the proinflammatory effect of extracellular HSP27 through toll-like receptor (TLR)-2 and TLR4.
abstract: The myocardial inflammatory response contributes to cardiac functional injury associated with heart surgery obligating global ischemia/reperfusion (I/R). Toll-like receptors (TLRs) play an important role in the mechanism underlying myocardial I/R injury. The aim of this study was to examine the release of small constitutive heat shock proteins (HSPs) from human and mouse myocardium after global ischemia and examine the role of extracellular small HSP in myocardial injury. HSP27 release was assessed by enzyme-linked immunosorbent assay. Anti-HSP27 was applied to evaluate the role of extracellular HSP27 in the postischemic inflammatory response and functional injury in mouse hearts. Isolated hearts and cultured coronary vascular endothelial cells were exposed to recombinant HSP27 to determine its effect on proinflammatory signaling and production of proinflammatory mediators. HSP27 levels were markedly elevated in coronary sinus blood of patients and in coronary effluent of mouse hearts after global ischemia. Neutralizing extracellular HSP27 suppressed myocardial nuclear factor (NF)-κB activation and interleukin (IL)-6 production and improved cardiac function in mouse hearts. Perfusion of HSP27 to mouse hearts induced NF-κB activation and IL-6 production and depressed contractility. Further, recombinant HSP27 induced NF-κB phosphorylation and upregulated monocyte chemoattractant protein (MCP)-1 and intercellular adhesion molecule (ICAM)-1 production in both human and mouse coronary vascular endothelial cells. TLR2 knockout (KO) or TLR4 mutation abolished NF-κB phosphorylation and reduced MCP-1 and ICAM-1 production induced by extracellular HSP27 in endothelial cells. In conclusion, these results show that the myocardium releases HSP27 after global ischemia and that extracellular HSP27 is proinflammatory and contributes to the inflammatory mechanism of myocardial functional injury. Both TLR2 and TLR4 are involved in mediating the proinflammatory effect of extracellular HSP27.
authors.affiliation: Department of Surgery, University of Colorado Denver, Aurora, Colorado, United States of America Center for Experimental Medicine, Southern Medical University, Guangzhou, China.
authors.forename: Chunhua
authors.initials: C
authors.lastname: Jin
authors.affiliation: Department of Surgery, University of Colorado Denver, Aurora, Colorado, United States of America.
authors.forename: Joseph C
authors.initials: JC
authors.lastname: Cleveland
authors.affiliation: Department of Surgery, University of Colorado Denver, Aurora, Colorado, United States of America.
authors.forename: Lihua
authors.initials: L
authors.lastname: Ao
authors.affiliation: Department of Surgery, University of Colorado Denver, Aurora, Colorado, United States of America Department of Cardiology, Southern Medical University, Guangzhou, China.
authors.forename: Jilin
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Surgery, University of Colorado Denver, Aurora, Colorado, United States of America Department of Cardiology, Southern Medical University, Guangzhou, China.
authors.forename: Qingchun
authors.initials: Q
authors.lastname: Zeng
authors.affiliation: Department of Surgery, University of Colorado Denver, Aurora, Colorado, United States of America.
authors.forename: David A
authors.initials: DA
authors.lastname: Fullerton
authors.affiliation: Department of Surgery, University of Colorado Denver, Aurora, Colorado, United States of America.
authors.forename: Xianzhong
authors.initials: X
authors.lastname: Meng
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism; D042783:Endothelial Cells; D055551:HSP27 Heat-Shock Proteins / Q000378:metabolism*; D006360:Heat-Shock Proteins; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D008297:Male; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018832:Molecular Chaperones; D015428:Myocardial Reperfusion Injury / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D051195:Toll-Like Receptor 2 / Q000378:metabolism*; D051197:Toll-Like Receptor 4 / Q000378:metabolism*
chemical_list: D016207:Cytokines; D055551:HSP27 Heat-Shock Proteins; C057725:HSPB1 protein, human; D006360:Heat-Shock Proteins; C486699:Hspb2 protein, mouse; D018832:Molecular Chaperones; D016328:NF-kappa B; C495342:TLR2 protein, human; C495345:TLR4 protein, human; C493486:Tlr2 protein, mouse; C493487:Tlr4 protein, mouse; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D018799:Intercellular Adhesion Molecule-1