title: Microparticles mediate hepatic ischemia-reperfusion injury and are the targets of Diannexin (ASP8597).
abstract: OBJECTIVE
  Ischemia-reperfusion injury (IRI) can cause hepatic failure after liver surgery or transplantation. IRI causes oxidative stress, which injures sinusoidal endothelial cells (SECs), leading to recruitment and activation of Kupffer cells, platelets and microcirculatory impairment. We investigated whether injured SECs and other cell types release microparticles during post-ischemic reperfusion, and whether such microparticles have pro-inflammatory, platelet-activating and pro-injurious effects that could contribute to IRI pathogenesis.
  
  
  METHODS
  C57BL6 mice underwent 60 min of partial hepatic ischemia followed by 15 min-24 hrs of reperfusion. We collected blood and liver samples, isolated circulating microparticles, and determined protein and lipid content. To establish mechanism for microparticle production, we subjected murine primary hepatocytes to hypoxia-reoxygenation. Because microparticles express everted phosphatidylserine residues that are the target of annexin V, we analyzed the effects of an annexin V-homodimer (Diannexin or ASP8597) on post-ischemia microparticle production and function.
  
  
  RESULTS
  Microparticles were detected in the circulation 15-30 min after post-ischemic reperfusion, and contained markers of SECs, platelets, natural killer T cells, and CD8+ cells; 4 hrs later, they contained markers of macrophages. Microparticles contained F2-isoprostanes, indicating oxidative damage to membrane lipids. Injection of mice with TNF-α increased microparticle formation, whereas Diannexin substantially reduced microparticle release and prevented IRI. Hypoxia-re-oxygenation generated microparticles from primary hepatocytes by processes that involved oxidative stress. Exposing cultured hepatocytes to preparations of microparticles isolated from the circulation during IRI caused injury involving mitochondrial membrane permeability transition. Microparticles also activated platelets and induced neutrophil migration in vitro. The inflammatory properties of microparticles involved activation of NF-κB and JNK, increased expression of E-selectin, P-selectin, ICAM-1 and VCAM-1. All these processes were blocked by coating microparticles with Diannexin.
  
  
  CONCLUSIONS
  Following hepatic IRI, microparticles circulate and can be taken up by hepatocytes, where they activate signaling pathways that mediate inflammation and hepatocyte injury. Diannexin prevents microparticle formation and subsequent inflammation.
authors.affiliation: Australian National University Medical School at The Canberra Hospital, Canberra, ACT, Australia.
authors.forename: Narci C
authors.initials: NC
authors.lastname: Teoh
authors.affiliation: Australian National University Medical School at The Canberra Hospital, Canberra, ACT, Australia.
authors.forename: Hussam
authors.initials: H
authors.lastname: Ajamieh
authors.affiliation: Australian National University Medical School at The Canberra Hospital, Canberra, ACT, Australia.
authors.forename: Heng Jian
authors.initials: HJ
authors.lastname: Wong
authors.affiliation: School of Medicine and Pharmacology, University of Western Australia, Perth, WA, Australia.
authors.forename: Kevin
authors.initials: K
authors.lastname: Croft
authors.affiliation: School of Medicine and Pharmacology, University of Western Australia, Perth, WA, Australia.
authors.forename: Trevor
authors.initials: T
authors.lastname: Mori
authors.affiliation: Alavita Inc, Palo Alto, California, United States of America.
authors.forename: Anthony C
authors.initials: AC
authors.lastname: Allison
authors.affiliation: Australian National University Medical School at The Canberra Hospital, Canberra, ACT, Australia.
authors.forename: Geoffrey C
authors.initials: GC
authors.lastname: Farrell
mesh_terms: D000818:Animals; D017304:Annexin A5 / Q000737:chemistry / Q000494:pharmacology*; D001792:Blood Platelets / Q000502:physiology; D002463:Cell Membrane Permeability; D002465:Cell Movement; D055252:Cell-Derived Microparticles / Q000378:metabolism* / Q000502:physiology; D019040:E-Selectin / Q000378:metabolism; D042783:Endothelial Cells / Q000378:metabolism; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D008099:Liver / Q000473:pathology; D008297:Male; D008810:Mice, Inbred C57BL; D008833:Microcirculation / Q000187:drug effects; D016328:NF-kappa B / Q000378:metabolism; D009504:Neutrophils / Q000502:physiology; D018384:Oxidative Stress; D019007:P-Selectin / Q000378:metabolism; D015427:Reperfusion Injury / Q000188:drug therapy / Q000473:pathology*; D015398:Signal Transduction / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D019010:Vascular Cell Adhesion Molecule-1 / Q000378:metabolism
chemical_list: D017304:Annexin A5; D019040:E-Selectin; D016328:NF-kappa B; D019007:P-Selectin; D014409:Tumor Necrosis Factor-alpha; D019010:Vascular Cell Adhesion Molecule-1; D018799:Intercellular Adhesion Molecule-1