title: Isolevuglandins, a novel class of isoprostenoid derivatives, function as integrated sensors of oxidant stress and are generated by myeloperoxidase in vivo.
abstract: Isolevuglandins (isoLGs) are a family of reactive gamma-ketoaldehydes generated by free radical oxidation of arachidonate-containing lipids through the isoprostane pathway. Elevated plasma levels of isoLG protein adducts are observed in subjects with atherosclerosis compared with age/gender-matched controls. However, mechanisms for the generation of isoLGs in vivo are not established. Here we show that free radical-induced peroxidation promoted by the myeloperoxidase (MPO)/H2O2 system of leukocytes serves as one mechanism for the generation of isoLGs in vivo. Using a Candida sepsis model of inflammation, we demonstrate 3.5- and 2.7-fold increases in iso[4]LGE2 and isoLGE2 adducts of plasma proteins after pathogen exposure in wild-type mice. Plasma levels of F2 isoprostanes were not significantly increased after pathogen challenge in this model. MPO knockout mice demonstrated significant reductions (34%, P=0.003) in plasma levels of iso[4]LGE2 protein adducts after pathogen challenge compared with wild-type mice. Mass spectrometry and immunochemical methods demonstrate MPO-dependent formation of iso[4]LGE2 and isoLGE2 phospholipids and their corresponding isoLG protein adducts in model systems. The present studies thus identify MPO as one pathway for generation of isoLGs in vivo. They also suggest that long-lived protein isoLG adducts may serve as an alternative integrated sensor of oxidant stress in vivo.
authors.affiliation: Department of Chemistry, Case Western Reserve University, Ohio, USA.
authors.forename: Eugenia
authors.initials: E
authors.lastname: Poliakov
authors.forename: Marie-Luise
authors.initials: ML
authors.lastname: Brennan
authors.forename: Jennifer
authors.initials: J
authors.lastname: Macpherson
authors.forename: Renliang
authors.initials: R
authors.lastname: Zhang
authors.forename: Wei
authors.initials: W
authors.lastname: Sha
authors.forename: Laura
authors.initials: L
authors.lastname: Narine
authors.forename: Robert G
authors.initials: RG
authors.lastname: Salomon
authors.forename: Stanley L
authors.initials: SL
authors.lastname: Hazen
mesh_terms: D000818:Animals; D016718:Arachidonic Acid / Q000032:analysis; D015415:Biomarkers / Q000097:blood; D002177:Candidiasis / Q000378:metabolism; D028421:Isoprostanes / Q000096:biosynthesis* / Q000097:blood / Q000145:classification; D008074:Lipoproteins / Q000378:metabolism; D008077:Lipoproteins, LDL / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009573:Nitrites / Q000378:metabolism; D018384:Oxidative Stress; D009195:Peroxidase / Q000235:genetics / Q000378:metabolism*; D010743:Phospholipids / Q000737:chemistry / Q000378:metabolism; D011458:Prostaglandins E / Q000737:chemistry / Q000378:metabolism; D018805:Sepsis / Q000378:metabolism
chemical_list: D015415:Biomarkers; D028421:Isoprostanes; D008074:Lipoproteins; D008077:Lipoproteins, LDL; D009573:Nitrites; D010743:Phospholipids; D011458:Prostaglandins E; D016718:Arachidonic Acid; D009195:Peroxidase