Role of oxidase and antioxidant enzymes in neutrophils and blood circulation in patients with acute coronary syndrome

Abstract

Acute coronary syndrome (ACS), a subcategory of cardiovascular diseases, has become a major cause of mortality and morbidity worldwide. Oxidative stress resulting from increased production of reactive oxygen species and decreased antioxidants plays a major role in the pathophysiology of ACS. This study evaluated the activities of certain oxidase and antioxidant enzymes in circulation and neutrophils to determine their roles in increased oxidative stress in patients with ACS. A total of 52 patients with ACS admitted in the coronary care unit of two tertiary hospitals and 52 healthy controls were enrolled. Blood samples were collected from all subjects, and various oxidase and antioxidant enzymes in neutrophils and circulation were assayed. The patients had significantly higher white blood cell and neutrophil counts than the controls. In patients, the mean (±SD) serum activities of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (12.83±6.6 U/L) and superoxidase dismutase (4.34±1.41 U/mL) were significantly higher than in the control group (4.88±3.03 U/L and 3.02±1.7 U/mL, respectively) while the catalase had significantly lower activities (33.36±13.16 U/mL vs. 63.98±31.86 U/mL). In neutrophils, the activities of myeloperoxidase, NADPH oxidase and catalase were significantly higher in ACS patients, while superoxidase dismutase was significantly lower. Further, significant positive correlations were found between activities of myeloperoxidase and catalase, and NADPH oxidase and superoxidase dismutase in neutrophils of ACS patients. These findings revealed that higher activities of myeloperoxidase and NADPH oxidase, both in serum and neutrophils, lead to increased oxidative stress and form the inflammatory basis of ACS, and the antioxidant enzymes combat the events.