Relationship between biomarkers and platelet aggregation activity in presence of hydrogen sulfide in patients with coronary heart disease

Biological significance of hydrogen sulfide (H₂S) in regulation of platelet functions and in development of thrombosis is being studied, but there is no consensus on the role of H₂S in these physiological processes. The platelets are very sensitive to various mediators released from blood vessels and blood cells. Multiple pro-inflammatory molecules may exert direct effects on the state of cardiovascular system. Thus, an imbalance in the production of pro-inflammatory and anti-inflammatory cytokines increases the risk of thrombosis, and it can lead to endothelial dysfunction, instability and rupture of atherosclerotic plaques. The aim of our study was to determine concentrations and identify the relationships between certain biomarkers (LIGHT, PlGF, IFNá2, TNFáâ, IL-3, IL-5, IL-6, IL-8, IL-15, IL-17F, MIP-1á, CXCL16) and collagen-induced platelet aggregation in presence of hydrogen sulfide exposure in patients with coronary heart disease. We performed a simple one-step comparative study which included 22 patients with coronary artery disease (CHD). The level of biomarkers was determined by multiplex analysis (xMAP technology). Platelet aggregation activity was studied by the turbidimetric assay. All samples were examined against the background of a 30-min pre-incubation with hydrogen sulfide, with the addition of an aggregation inducer (collagen, 2 mmol/L). Sodium hydrosulfide at a concentration of 10^-6 M was used as a hydrogen sulfide donor. The results of comparative and correlation analysis were considered reliable at a statistical significance level of p < 0.05. The patients were divided into two groups, i.e., group 1 (n = 10) showed a reduced aggregation or a decreased size of aggregates against the background of preincubation with H₂S. In group 2 (n = 12), preincubation with H₂S was followed by increased degree or size of platelet aggregates. The concentrations of tumor necrosis factor ligand (LIGHT), interferon IFNá2, interleukins IL-3, IL-8, IL-15, IL-17F, chemokine CCL3/MIP-1a were significantly increased in group 2 patients, where collagen-induced platelet aggregation increased upon preincubation H₂S, as compared with patients in group 1. The correlation analysis revealed positive correlations found that in the 1^st group of patients between the concentrations of MIP-1a (Rs = 0.56, p = 0.03; Rs = 0.69, p = 0.01), IL-5 (Rs = 0.83, p = 0.01; Rs = 0.73, p = 0.01), and IL-8 (Rs = 0.60, p = 0.02; Rs = 0.95, p = 0.01), respectively, and with both size of aggregates and the index of the platelet aggregation degree. Moreover, distinct correlations between the aggregate size and the concentration of IL-6 (Rs = 0.53, p = 0.04) were revealed. In the 2^nd group of patients, correlations were found with the size of aggregates and PIGF (Rs = 0.59, p = 0.04), and between CXCL16 values and the size of aggregates (Rs = 0.58, p = 0.04), like as with the degree of aggregation (Rs = 0.65, p = 0.04). Thus, we have found that, in 2 groups of patients with coronary heart disease with increased collagen-induced platelet aggregation, preincubated with H₂S, higher concentrations of inflammatory biomarkers (IFNá2, IL-3, IL-8, IL-15, IL-17F, MIP-1á) were detected. One may suggest that the more pronounced proinflammatory state in this group of patients may cause platelet resistance to inhibitory effect of hydrogen sulfide. In the 1^st group of patients, we revealed multiple correlations of aggregation parameters with values of inflammatory markers (IL-5, IL-6, IL-8, MIP- 1a), which may be a pre-requisite for different corrective therapies for the patients of these groups.