title: Heme oxygenase-1 production by peripheral blood monocytes during acute inflammatory illnesses of children.
abstract: Monocytes play key roles both in innate and adaptive antigen-specific immunity and they constitute critical components of the immune responses. Although most of the monocyte-derived cytokines exhibit proinflammatory functions in vivo, heme oxygenase-1 (HO-1), an inducible heme-degrading enzyme, exerts potent anti-inflammatory effect through production of carbon monoxide and bilirubin. We compared HO-1 production by monocytes in vivo in various acute inflammatory illnesses and in normal controls. Freshly isolated monocytes produced little HO-1 as detected by immunohistochemistry, but it was rapidly induced in vitro upon stimulation. HO-1 production by monocytes was selective because it was not induced in other leukocyte populations, including granulocytes and lymphocytes. Monocytes from acute inflammatory illnesses, such as Kawasaki disease and acute infectious diseases, viral or bacterial, produced significant levels of HO-1, as detected by flow cytometry, immunohistochemistry, and reverse transcription polymerase chain reaction. Quantitative analysis of HO-1 mRNA expression by real-time polymerase chain reaction revealed that monocytes from controls exhibited low, but significant levels of HO-1 mRNA, indicating that circulating monocytes produce HO-1 constantly, in response to basal level of oxidative stress encountered daily. Significantly elevated HO-1 mRNA levels seen in acute inflammatory illnesses suggest that monocyte HO-1 production serve as potent anti-inflammatory agent to control excessive cell or tissue injury in the presence of oxidative stress and cytokinemia.
authors.affiliation: Department of Laboratory Sciences, School of Health Sciences, Faculty of Medicine, Kanazawa University, Kanazawa 920-0942, Japan. yachie@med.kanazawa-u.ac.jp
authors.forename: Akihiro
authors.initials: A
authors.lastname: Yachie
authors.forename: Tomoko
authors.initials: T
authors.lastname: Toma
authors.forename: Kazunori
authors.initials: K
authors.lastname: Mizuno
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Okamoto
authors.forename: Shoetsu
authors.initials: S
authors.lastname: Shimura
authors.forename: Kazuhide
authors.initials: K
authors.lastname: Ohta
authors.forename: Yoshihito
authors.initials: Y
authors.lastname: Kasahara
authors.forename: Shoichi
authors.initials: S
authors.lastname: Koizumi
mesh_terms: D001424:Bacterial Infections / Q000097:blood / Q000201:enzymology; D002478:Cells, Cultured; D002648:Child; D006419:Heme Oxygenase (Decyclizing) / Q000235:genetics / Q000378:metabolism*; D051547:Heme Oxygenase-1; D006801:Humans; D007244:Infectious Mononucleosis / Q000097:blood / Q000201:enzymology; D007249:Inflammation / Q000097:blood* / Q000201:enzymology*; D008214:Lymphocytes / Q000166:cytology / Q000378:metabolism; D008565:Membrane Proteins; D009000:Monocytes / Q000166:cytology / Q000201:enzymology*; D009080:Mucocutaneous Lymph Node Syndrome / Q000097:blood / Q000201:enzymology; D012333:RNA, Messenger / Q000378:metabolism; D014777:Virus Diseases / Q000097:blood / Q000201:enzymology
chemical_list: D008565:Membrane Proteins; D012333:RNA, Messenger; C496541:HMOX1 protein, human; D006419:Heme Oxygenase (Decyclizing); D051547:Heme Oxygenase-1