Abstract
Objective: Myeloperoxidase (MPO) is an inflammatory enzyme that is mainly released by activated neutrophils and monocytes. 3-nitrotyrosine (NT) is a stable inflammatory end product of MPO that is produced through nitrosylation of free and protein-bound tyrosines. Determination of the exact levels of free NT is technically a challenging matter. Also, there is limited information about the relationship between MPO and free NT levels and elevation of them in the plasma of patients with coronary artery disease (CAD). Therefore, we sought to determine the exact level of plasma free NT with a simple and exquisite technique in CAD patients. Methods: This study included 50 stable angina, 50 unstable angina patients, and 50 control subjects. Plasma MPO concentration was measured with an immunoassay method. Plasma free NT level was determined by a modified HPLC-fluorescence method. Lipid profile, high sensitivity C-reactive protein (hsCRP) and other clinical risk factors of patients were also assigned. Results: Plasma level of free NT was efficiently measured by the HPLC-fluorescence method. Plasma levels of MPO and NT were significantly higher in patients with stable and unstable CAD than in control subjects (P Conclusions: We determined plasma free NT levels with a sensitive HPLC-fluorescence method with some modifications in a clinical scale. Plasma levels of MPO and NT were profoundly elevated in CAD patients. The significant relationships of the two substances and elevation of them may have useful clinical implication in patients with stable and unstable CAD.
Highlights
Myeloperoxidase (MPO) is an inflammatory enzyme that is mainly produced by neutrophils and monocytes
Myeloperoxidase (MPO) is an inflammatory enzyme that is mainly released by activated neutrophils and monocytes. 3-nitrotyrosine (NT) is a stable inflammatory end product of MPO that is produced through nitrosylation of free and protein-bound tyrosines
Plasma levels of MPO and NT were significantly higher in patients with stable and unstable coronary artery disease (CAD) than in control subjects (P < 0.001)
Summary
Myeloperoxidase (MPO) is an inflammatory enzyme that is mainly produced by neutrophils and monocytes. MPO nitrosylates the tyrosine residues of apo A-I component of high density lipoprotein (HDL) and thereby interferes with cholesterol efflux from macrophages [8]. MPO produces reactive nitrogen species that convert low density lipoprotein (LDL) into an atherogenic form. This modified LDL is endocytosed by macrophages, leading to foam cell transformation [9]. The colocalization of both MPO and nitrotyrosine in the subendothelial space of arteries [10] further stressed the role of MPO and NT in inflammatory diseases, such as CAD
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