Formation of nitric oxide-derived oxidants by myeloperoxidase in monocytes pathways for monocyte-mediated protein nitration and lipid peroxidation in vivo

Stanley L. Hazen, Renliang Zhang, Zhongzhou Shen, Weijia Wu, Eugene A. Podrez, Jennifer C. MacPherson, David Schmitt, Shome N. Mitra, Chaitali Mukhopadhyay, Yonghong Chen, Peter A. Cohen, Henry F. Hoff, Husam M. Abu-Soud

Research output: Contribution to journalArticlepeer-review

193 Scopus citations


Protein nitration and lipid peroxidation are implicated in the pathogenesis of atherosclerosis; however, neither the cellular mediators nor the reaction pathways for these events in vivo are established. In the present study, we examined the chemical pathways available to monocytes for generating reactive nitrogen species and explored their potential contribution to the protein nitration and lipid peroxidation of biological targets. Isolated human monocytes activated in media containing physiologically relevant levels of nitrite (NO2/-), a major end product of nitric oxide (NO) metabolism, nitrate apolipoprotein B-100 tyrosine residues and initiate LDL lipid peroxidation. LDL nitration (assessed by gas chromatography-mass spectrometry quantification of nitrotyrosine) and lipid peroxidation (assessed by high-performance liquid chromatography with online tandem mass spectrometric quantification of distinct products) required cell activation and NO2/-; occurred in the presence of metal chelators, superoxide dismutase (SOD), and scavengers of hypohalous acids; and was blocked by myeloperoxidase (MPO) inhibitors and catalase. Monocytes activated in the presence of the exogenous NO generator PAPA NONOate (Z-[N-{3- aminopropyl}-N-{npropyl}amino]diazen-1-ium-1,2-diolate) promoted LDL protein nitration and lipid peroxidation by a combination of pathways. At low rates of NO flux, both protein nitration and lipid peroxidation were inhibited by catalase and peroxidase inhibitors but not SOD, suggesting a role for MPO. As rates of NO flux increased, both nitrotyrosine formation and 9-hydroxy- 10,12-octadecadienoate/9-hydroperoxy-10,12-octadecadienoic acid production by monocytes became insensitive to the presence of catalase or peroxidase inhibitors, but they were increasingly inhibited by SOD and methionine, suggesting a role for peroxynitrite. Collectively, these results demonstrate that monocytes use distinct mechanisms for generating NO-derived oxidants, and they identify MPO as a source of nitrating intermediates in monocytes.

Original languageEnglish (US)
Pages (from-to)950-958
Number of pages9
JournalCirculation research
Issue number10
StatePublished - Nov 12 1999


  • Atherosclerosis
  • Lipid peroxidation
  • Nitric oxide
  • Nitrotyrosine

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine


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