title: Osteopontin Is a Blood Biomarker for Microglial Activation and Brain Injury in Experimental Hypoxic-Ischemic Encephalopathy.
abstract: Clinical management of neonatal hypoxic-ischemic encephalopathy (HIE) suffers from the lack of reliable surrogate marker tests. Proteomic analysis may identify such biomarkers in blood, but there has been no proof-of-principle evidence to support this approach. Here we performed in-gel trypsin digestion of plasma proteins from four groups of 10-d-old mice [untouched and 24 h after low-dose lipopolysaccharide (LPS) exposure, hypoxia-ischemia (HI), or LPS/HI injury;n= 3 in each group) followed by liquid chromatography-tandem mass spectrometry and bioinformatics analysis to search for HI- and LPS/HI-associated brain injury biomarkers. This analysis suggested the induction of plasma osteopontin (OPN) by HI and LPS/HI, but not by sham and injury-free LPS exposure. Immunoblot confirmed post-HI induction of OPN protein in brain and blood, whereasOpnmRNA was induced in brain but not in blood. This disparity suggests brain-derived plasma OPN after HI injury. Similarly, immunostaining showed the expression of OPN by Iba1+microglia/macrophages in HI-injured brains. Further, intracerebroventricular injection of LPS activated microglia and up-regulated plasma OPN protein. Importantly, the induction of plasma OPN after HI was greater than that of matrix metalloproteinase 9 or glial fibrillary acid protein. Plasma OPN levels at 48 h post-HI also parallel the severity of brain damage at 7-d recovery. Together, these results suggest that OPN may be a prognostic blood biomarker in HIE through monitoring brain microglial activation.
authors.affiliation: Department of Pediatrics, Emory University School of Medicine , and Children's Healthcare of Atlanta , Atlanta, GA 30322.
authors.forename: Yikun
authors.identifier: 0000-0002-2117-8057
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Biochemistry, Emory University School of Medicine , Atlanta, GA 30322.
authors.forename: Eric B
authors.identifier: 0000-0003-2947-7606
authors.initials: EB
authors.lastname: Dammer
authors.affiliation: Department of Pediatrics, Emory University School of Medicine , and Children's Healthcare of Atlanta , Atlanta, GA 30322.
authors.forename: Xiaohui
authors.identifier: 0000-0003-1390-7501
authors.initials: X
authors.lastname: Zhang-Brotzge
authors.affiliation: Department of Pediatrics, Emory University School of Medicine , and Children's Healthcare of Atlanta , Atlanta, GA 30322.
authors.forename: Scott
authors.identifier: 0000-0003-0948-530X
authors.initials: S
authors.lastname: Chen
authors.affiliation: Department of Biochemistry, Emory University School of Medicine , Atlanta, GA 30322.
authors.forename: Duc M
authors.identifier: 0000-0001-5880-1888
authors.initials: DM
authors.lastname: Duong
authors.affiliation: Department of Biochemistry, Emory University School of Medicine , Atlanta, GA 30322.
authors.forename: Nicholas T
authors.initials: NT
authors.lastname: Seyfried
authors.affiliation: Department of Pediatrics, Emory University School of Medicine , and Children's Healthcare of Atlanta , Atlanta, GA 30322.
authors.forename: Chia-Yi
authors.initials: CY
authors.lastname: Kuan
authors.affiliation: Department of Pediatrics, Emory University School of Medicine , and Children's Healthcare of Atlanta , Atlanta, GA 30322.
authors.forename: Yu-Yo
authors.initials: YY
authors.lastname: Sun
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000097:blood; D001921:Brain / Q000276:immunology / Q000473:pathology; D002135:Calcium-Binding Proteins / Q000378:metabolism; D016893:Carotid Stenosis; D004195:Disease Models, Animal; D004660:Encephalitis / Q000097:blood / Q000276:immunology / Q000473:pathology; D005260:Female; D020925:Hypoxia-Ischemia, Brain / Q000097:blood* / Q000276:immunology* / Q000473:pathology; D008070:Lipopolysaccharides; D008264:Macrophages / Q000378:metabolism / Q000473:pathology; D008297:Male; D008810:Mice, Inbred C57BL; D008840:Microfilament Proteins / Q000378:metabolism; D017628:Microglia / Q000378:metabolism* / Q000473:pathology; D053495:Osteopontin / Q000097:blood*; D020543:Proteome; D012720:Severity of Illness Index
chemical_list: C491049:Aif1 protein, mouse; D015415:Biomarkers; D002135:Calcium-Binding Proteins; D008070:Lipopolysaccharides; D008840:Microfilament Proteins; D020543:Proteome; C506896:Spp1 protein, mouse; D053495:Osteopontin
keywords: HIE; LC-MS/MS; hypoxia-ischemia