Immunephenotyping of monocyte migration markers and therapeutic effects of selenium on IL-6 and IL-1β cytokine axes of blood mononuclear cells in preoperative and postoperative coronary artery disease patients

Cardiovascular diseases (CVDs) are the first leading cause of death worldwide, according to the World Health Organization, where coronary artery disease (CAD) is gaining more importance due to the deposition of atherosclerotic plaques and subsequent blockage of the arteries. Chronic inflammation is the main pathological drivers for atherosclerosis, the underlying mechanism of all CVD, where circulating blood monocytes serve as one of the inflammatory cell subsets that are highly heterogeneous in nature and are classified into three subgroups: classical, intermediate and pro-inflammatory monocytes. In addition, pro-inflammatory cytokines secreted by the mononuclear cells are pivotal in sustaining the state of inflammation in coronary artery disease. Hence, the main aim of the study is to investigate the existing state of inflammation among CAD patients in terms of (i) mononuclear cells subtypes and (ii) pro-inflammatory cytokines and to intervene the inflamed state with a therapeutic concentration of selenium, in in-vitro. CAD patients and normal controls were recruited and evaluated for (i) frequencies of blood monocytes and functional migration markers using flow cytometry; (ii) the plasma levels of pro-inflammatory cytokines (IL-6 and TNF-a), using ELISA. An in-vitro effects of selenium on CAD mononuclear cells was evaluated for phosphorylation (p) of STAT-3 transcription factors that regulates IL-6 cytokine, using western blot.The frequencies of pro-inflammatory monocytes were significantly increased among CAD patients and significant increase in migration marker, CCR1 expression, was restricted to classical and intermediate monocytes. Further, CAD patient exhibited increased plasma IL-6 cytokine, reflecting the ongoing status of inflammation among these patients. Interestingly, an in-vitro intervention with selenium has minimized the pSTAT3 activity and decreased the concentration of pro-inflammatory cytokines, including IL-6 and TNF-a. Furthermore, the frequencies of both intermediate and pro-inflammatory monocytes were markedly reduced upon selenium treatment. Taken together, the CAD patients exhibited ongoing inflammation, where increased CCR1 expression on classical monocytes reflects their differentiation process, possibly into inflamed monocytes or macrophages. Furthermore, we also conclude that selenium could minimize the inflammation by hampering STAT-3/IL-6 axis and monocytes differentiation.