Cytokine markers of clinical variants of infective endocarditis

Introduction. Infective endocarditis is a bacterial disease. Pathogen is localized mainly on heart valves and endocardium. This condition is accompanied by immunopathological manifestations and potential generation of septic process being unfavorable prognosis for disease outcome. Currently, the causes of death of patients with endocarditis have been increasingly presented as thromboembolic complications, which severity depends on variant of the disease course. An important role in imbalanced immune system in the infectious process is assigned to altered intercellular interaction mediated via cytokine network. Activated immune cells produce cytokines, which investigating is important in terms of interpreting changes in immune system functionality, assessing the severity of diseases and controlling therapeutic effectiveness. Infective endocarditis remains a severe disease associated with high mortality despite current advances in diagnostics and treatment. A timely diagnostic process and early initiation of treatment are major factors for successful patient management necessitating to improve diagnostics of various clinical variants of endocarditis course, taking into account pathogenetically relevant cytokines. Objective was to comparatively evaluate the importance of serum cytokine concentrations in patients with uncomplicated course of infective endocarditis and its thromboembolic complications and determine cytokine markers of various variants of endocarditis course. Materials and methods. An immunological examination of 119 blood serum samples from patients with confirmed diagnosis of infectious endocarditis and 20 samples from apparently healthy persons was carried out. Depending on the clinical disease form, the patients were divided into 4 groups: group 1 — primary infective endocarditis (PIE) with thromboembolic complications (n = 24), 2 — PIE without thromboembolic complications (n = 34), 3 — secondary IE with thromboembolic complications (n = 27), 4 — secondary IE without thromboembolic complications (n = 34). The control group consisted of 20 apparently healthy subjects. Immunological studies of serum cytokine concentrations were conducted in all groups. Results. Statistically significant increase in serum concentration of IL-10, IL-6, VEGF-A, IL-18, IL-1Ra and IL-8 was revealed in all clinical groups of patients compared to those in control group (p < 0,05). By correlation analysis, we found a significant positive relationship between IL-10 and IL-18 or IL-6. An increase in the concentration of IL-10 leads to increased level of pro-inflammatory IL-18 and IL-6. The marker of secondary endocarditis was observed as increased level of serum concentrations of IFNγ. A characteristic feature of primary infective endocarditis with thromboembolic complications was revealed as significantly increased serum concentration of IL-8, IL-1Ra and IL-6. Markers of secondary complicated endocarditis were identified as increased level of IL-6, VEGF-A and IL-18.