title: Heme oxygenase-1 induction in macrophages by a hemoglobin-based oxygen carrier reduces endotoxin-stimulated cytokine secretion.
abstract: The inflammatory response after an insult may provoke further tissue damage, and the macrophage is central in this pathophysiology. Induction of heme oxygenase-1 (HO-1) attenuates postshock organ dysfunction, although the mechanism remains unclear. We hypothesized that HO-1 induction modifies the cytokine profile of LPS-stimulated macrophages. Heme oxygenase-1 was induced in murine and human macrophages with varying concentrations of a hemoglobin-based oxygen carrier (HBOC). Heme oxygenase-1 expression was analyzed by Western blotting of whole cell lysates. Macrophages were pretreated with HBOC for 4 h, then media with LPS were added for up to 24 h. The specific HO-1 inhibitor zinc protoporphyrin (ZnPP) was used to inhibit the effects of HO-1. Supernatants were analyzed for IL-6, IL-10, TNF-alpha, and monocyte chemotactic protein 1 (MCP-1) by enzyme-linked immunosorbent assay. Incubation of cells with HBOC produced a dose-dependent expression of HO-1. Heme oxygenase-1 expression decreased LPS-stimulated secretion of MCP-1, IL-6, IL-10, and TNF-alpha at both 4 and 24 h in murine and human macrophages. The addition of ZnPP to inhibit HO-1 partially restored MCP-1 and IL-6 secretion in murine macrophages. Furthermore, immunofluorescent microscopy revealed HBOC-induced HO-1 inhibited LPS-stimulated nuclear translocation of the p65 subunit of nuclear factor-kappaB. In summary, HBOC incubation of macrophages induced HO-1 expression, which reduced LPS-mediated cytokine release, and that MCP-1 and IL-6 secretion could be partially restored with ZnPP. These data encourage continued investigation into the role of HO-1 in protecting against posttraumatic organ dysfunction and the clinical potential of HBOC for HO-1 induction.
authors.affiliation: Department of Surgery, The University of Colorado Denver, Aurora, USA.
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Roach
authors.forename: Ernest E
authors.initials: EE
authors.lastname: Moore
authors.forename: David A
authors.initials: DA
authors.lastname: Partrick
authors.forename: Sagar S
authors.initials: SS
authors.lastname: Damle
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Silliman
authors.forename: Robert C
authors.initials: RC
authors.lastname: McIntyre
authors.forename: Anirban
authors.initials: A
authors.lastname: Banerjee
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000187:drug effects / Q000276:immunology; D000818:Animals; D001802:Blood Substitutes / Q000494:pharmacology*; D002460:Cell Line; D002467:Cell Nucleus / Q000276:immunology / Q000378:metabolism; D016207:Cytokines / Q000096:biosynthesis* / Q000276:immunology; D004790:Enzyme Induction / Q000187:drug effects / Q000276:immunology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D051547:Heme Oxygenase-1 / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000276:immunology; D006454:Hemoglobins / Q000494:pharmacology*; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology*; D051379:Mice; D011524:Protoporphyrins / Q000494:pharmacology; D013997:Time Factors; D051996:Transcription Factor RelA / Q000276:immunology / Q000378:metabolism
chemical_list: D001802:Blood Substitutes; D016207:Cytokines; D004791:Enzyme Inhibitors; D006454:Hemoglobins; D008070:Lipopolysaccharides; D011524:Protoporphyrins; C498143:RELA protein, human; C498144:Rela protein, mouse; D051996:Transcription Factor RelA; C017803:zinc protoporphyrin; C496541:HMOX1 protein, human; D051547:Heme Oxygenase-1