title: Loss of 3-chlorotyrosine by inflammatory oxidants: implications for the use of 3-chlorotyrosine as a bio-marker in vivo.
abstract: Activated neutrophils generate the potent oxidant hypochlorous acid (HOCl) from the enzyme myeloperoxidase (MPO). A proposed bio-marker for MPO-derived HOCl in vivo is 3-chlorotyrosine, elevated levels of which have been measured in several human inflammatory pathologies. However, it is unlikely that HOCl is produced as the sole oxidant at sites of chronic inflammation as other reactive species are also produced during the inflammatory response. The work presented shows that free and protein bound 3-chlorotyrosine is lost upon addition of the pro-inflammatory oxidants, HOCl, peroxynitrite, and acidified nitrite. Furthermore, incubation of 3-chlorotyrosine with activated RAW264.7 macrophages or neutrophil-like HL-60 cells resulted in significant loss of 3-chlorotyrosine. Therefore, at sites of chronic inflammation where there is concomitant ONOO(-) and HOCl formation, it is possible measurement of 3-chlorotyrosine may represent an underestimate of the true extent of tyrosine chlorination. This finding could account for some of the discrepancies reported between 3-chlorotyrosine levels in tissues in the literature.
authors.affiliation: Institute of Biomedical and Clinical Sciences, Peninsula Medical School, St. Luke's Campus, Magdalen Road, Exeter, EX1 2LU England, UK. matt.whiteman@pms.ac.uk
authors.forename: Matthew
authors.initials: M
authors.lastname: Whiteman
authors.forename: Jeremy P E
authors.initials: JP
authors.lastname: Spencer
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis / Q000378:metabolism; D018922:HL-60 Cells; D006801:Humans; D006997:Hypochlorous Acid / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D007249:Inflammation / Q000378:metabolism*; D008262:Macrophage Activation; D008264:Macrophages / Q000187:drug effects / Q000276:immunology; D051379:Mice; D009504:Neutrophils / Q000187:drug effects / Q000276:immunology; D009573:Nitrites / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D016877:Oxidants / Q000378:metabolism / Q000494:pharmacology; D009195:Peroxidase / Q000378:metabolism; D030421:Peroxynitrous Acid / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology
chemical_list: D015415:Biomarkers; D009573:Nitrites; D016877:Oxidants; D017382:Reactive Oxygen Species; D030421:Peroxynitrous Acid; D014443:Tyrosine; D006997:Hypochlorous Acid; D009195:Peroxidase; C087259:3-chlorotyrosine