Extensive Nitration of Protein Tyrosines in Human Atherosclerosis Detected by Immunohistochemistry

Abstract

Oxidation of lipoproteins is important for the initiation and propagation of the atherosclerotic lesion and may involve secondary oxidants derived from nitric oxide. Nitric oxide (NO) reacts at near diffusion limited rates with superoxide (O2-.) to form the strong oxidant, peroxynitrite (ONOO-). Nitration on the ortho position of tyrosine is a major product of peroxynitrite attack on proteins. Nitrotyrosine was detected in atherosclerotic lesions of formalin-fixed human coronary arteries with polyclonal and monoclonal antibodies. Binding was pronounced in and around foamy macrophages within the atheroma deposits. Nitration was also observed in early subintimal fatty streaks. Antibody binding was completely blocked by co-incubation with 10mM nitrotyrosine, but not by equivalent concentrations of aminotyrosine or phosphotyrosine. The presence of nitrotyrosine indicates that oxidants derived from nitric oxide such as peroxynitrite are generated in human atherosclerosis and may be involved in its pathogenesis.

Protection against peroxynitrite‐dependent tyrosine nitration and α1‐antiproteinase inactivation by oxidized and reduced lipoic acid

“…Peroxynitrite generation in vivo is being implicated in a wide range of human diseases, including atherosclerosis [13], lung disease [12], neurodegenerative disorders [9] and chronic inflammation [14,21]. Hence agents able to protect against ONOO--dependent damage may be therapeutically useful.…”

“…When tyrosine is exposed to ONOO-at physiological pH, nitration occurs [10,12,13,16,17]. compounds (GSH, DHLA and penicillamine) could prevent this nitration whereas the disulphides GSSG and penicillamine were much less effective.…”

“…Although nitric oxide (NO') has many important physiological functions [11], its production in excess may contribute to the pathology of neurodegenerative disease, chronic inflammation, acute respiratory distress syndrome, atherosclerosis and septic shock [9][10][11][12][13][14]. Part of the toxicity of NO" involves its reaction with superoxide radical (02 °-) to give peroxynitrite, ONOO-…”

“…In particular, addition of peroxynitrite to biological fluids leads to nitration of tyrosine residues, and the presence of these appears to be a 'marker' of peroxynitrite-dependent damage in vivo [10,[12][13][14][15][16]. Tyrosine nitration can interfere with signal transduction mechanisms involving phosphorylation/dephosphorylation [17].…”

Systemic human Netrin-1 gene delivery by adeno-associated virus type 8 alters leukocyte accumulation and atherogenesis in vivo

“…We therefore analyzed the aortic sections for nitrotyrosine expression by immunohistochemistry. 8,19 There was a significant increase in nitrotyrosine immunopositivity in the AAV/Neo-treated LDLR KO mice on HCD (vs ND-fed animals) ( Figure 7a). In sharp contrast, mice injected with AAV/hNetrin-1 showed only very low level of nitrotyrosine staining despite the HCD.…”