Inductive No-synthase activity and citlulline content in blood serum as markers of immuno-inflammatory activation and oxidative stress under chronic heart failure

Abstract

Summary. Nitric oxide (NO) is a powerful endothelium-relaxing factor that causes vascular smooth muscle relaxation, inhibits their proliferation, and participates in the regulation of systemic and pulmonary vascular resistance, platelet aggregation processes, blood clotting and more.

The aim of the study – to investigate iNOS activity, immunoinflammatory response and oxidative stress intensity in chronic heart failure (CHF).

Materials and Methods. The study was performed on the basis of the Department of Heart Failure of the Institute of Cardiology named after Acad. M. D. Strazhesk, National Academy of Medical Sciences of Ukraine. 120 patients with CHF of both sexes aged (63±3.4) were examined, 76 of them with coronary heart disease (CHD) and 44 with hypertension. The criteria for involving patients in the study were: 1) CHF class II-IV according to NYHA with LV HF (ejection fraction (EF) of LV ≤45 %); 2) age ≤75 years. Exclusion criteria for the study were: 1) age> 75 years;  2) LV EF ≥45% according to echocardiographic examination; 3) CHF as a consequence of valve defects, inflammatory heart disease; 4) hypertrophic and restrictive cardiomyopathy; 5) acute coronary heart disease; 6) suffered a stroke or transient ischemic attack <6 months old; 7) oncological diseases; 8) acute infectious diseases. Statistical processing of the results was performed using the application package Statistica for Windows. Significance of diffe­rences between quantitative traits with normal distribution was performed using the odd Student's t-test. When comparing the two independent groups, the Mann-Whitney test (U) and the Wilcoxon test (W) were used for the two independent groups if the distribution of the indicator did not correspond to normal. The difference was considered statistically significant at p <0.05.

Results. We examined 120 patients with CHF of both sexes aged (63±3.4), including 76 with coronary heart disease and 44 with arterial hypertension. Studies have shown that the formation of oxidative stress is observed in CHF, as indicated by an increase in the content of oxidation products of lipids, proteins in serum and lipoprotein fractions. Intensification of free radical oxidative processes occurs against the background of significant inhibition of the activity of antioxidant defense systems – catalase and superoxide dismutase. At the same time, there is a decrease in the level of reduced glutathione and paraoxonase-1 activity. The presence of immunoinflammatory activation is indicated by a doubling of serum ceruloplasmin and proinflammatory cytokines IL-6 and TNF-α. The results of the NBT-test with immunocompetent cells indicate an increase in phagocytic activity of cells in a systemic inflammatory response. The doubling of the activity of the enzyme myeloperoxidase in the blood of the examined patients also serves as evidence of the activity of neutrophils and monocytes in the systemic inflammatory response. These changes in immuno-biochemical parameters were accompanied by an increase in the total content of citrulline in the serum by two or more times. This may be the result of excessive activation of the inducible isoform of NO-synthase under conditions of inflammatory reaction and under the influence of elevated levels of proinflammatory cytokines. The activity of the iNOS isoform under these conditions was increased threefold.

Conclusions. In the relationship between systemic immune activation and the intensity of oxidative stress, activation of iNOS in blood cells and the cardiovascular system can be considered an important link. Therefore, iNOS acti­vity and increased circulating levels of citrulline can be considered markers of immune activation and oxidative stress, which cause the progression of underlying cardiovascular disease and CHF.