title: Thrombomodulin's lectin-like domain reduces myocardial damage by interfering with HMGB1-mediated TLR2 signalling.
abstract: OBJECTIVE
  Thrombomodulin (TM), via its lectin-like domain (LLD), exhibits anti-inflammatory properties partly by sequestering the pro-inflammatory cytokine, high-mobility group box 1 (HMGB1). Since myocardial damage after ischaemia and reperfusion is mediated by inflammation, we evaluated the cardioprotective effects of the LLD of TM. Using an in vivo mouse model of transient ischaemia and in vitro models of cardiomyocyte hypoxia, we assessed the ability of the LLD to suppress HMGB1-mediated activation of the receptors, receptor for advanced glycation endproducts (RAGEs) and Toll-like receptors (TLRs) 2 and 4.
  
  
  RESULTS
  Thirty-minute myocardial ischaemia was induced in isoflurane-anaesthetized mice followed by 24 h of reperfusion in wild-type (WT) mice, in mice lacking the LLD of TM (TM(LeD/LeD) mice), and in WT with systemic overexpression of the LLD of TM induced by hydrodynamic transfection. Infarct size, HMGB1 protein, and apoptotic cells were significantly increased in TM(LeD/LeD) mice when compared with WT. Neonatal rat cardiomyocytes transfected with TLR2-, TLR4-, and RAGE-siRNA were exposed to hypoxia (0.8% O2) and reoxygenation (21% O2). HMGB1 augmented hypoxia-induced apoptosis in TLR2- but not in RAGE- or TLR4-suppressed cells. Administration of HMGB1- and TLR2-blocking antibodies in TM(LeD/LeD) mice prior to myocardial ischaemia diminished apoptosis. Therapeutic systemic gene therapy using the LLD reduced the infarct size and HMGB1 protein levels 24 h after reperfusion.
  
  
  CONCLUSIONS
  The LLD of TM suppresses HMGB1-induced and TLR2-mediated myocardial reperfusion injury and apoptosis in vitro and in vivo.
authors: Department of Anesthesiology and Intensive Care Medicine, Hannover Medical School, Carl-Neuberg Str. 1, Hannover 30625, Germany.
authors: Christine
authors: C
authors: Herzog
authors: Anika
authors: A
authors: Lorenz
authors: Hans-Jörg
authors: HJ
authors: Gillmann
authors: Arpita
authors: A
authors: Chowdhury
authors: Jan
authors: J
authors: Larmann
authors: Thomas
authors: T
authors: Harendza
authors: Frank
authors: F
authors: Echtermeyer
authors: Martin
authors: M
authors: Müller
authors: Martina
authors: M
authors: Schmitz
authors: Jörg
authors: J
authors: Stypmann
authors: Daniela G
authors: DG
authors: Seidler
authors: Martin
authors: M
authors: Damm
authors: Sebastian N
authors: SN
authors: Stehr
authors: Thea
authors: T
authors: Koch
authors: Kai C
authors: KC
authors: Wollert
authors: Edward M
authors: EM
authors: Conway
authors: Gregor
authors: G
authors: Theilmeier
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D002478:Cells, Cultured; D024243:HMGB1 Protein / Q000378:metabolism*; D007249:Inflammation / Q000235:genetics / Q000378:metabolism; D051379:Mice; D015428:Myocardial Reperfusion Injury / Q000235:genetics / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology; D018180:Thrombomodulin / Q000235:genetics / Q000378:metabolism*; D051195:Toll-Like Receptor 2 / Q000378:metabolism*
chemical_list: D024243:HMGB1 Protein; C582808:HMGB1 protein, mouse; D018180:Thrombomodulin; C493486:Tlr2 protein, mouse; D051195:Toll-Like Receptor 2
keywords: Apoptosis; High-mobility group box 1; Myocardial ischaemia; Thrombomodulin; Toll-like receptors