Interleukin 6 (IL-6) is a pleiotropic cytokine involved in both inflammatory reaction and myocardial response to stress. Its effects largely depend on the concentration of the soluble receptors (sIL-6R and sgp130). We investigated the production of IL-6, sIL-6R and sgp130 by the heart during ischemia and reperfusion.
Methods: The levels of IL-6 were determined in blood of 34 patients with first myocardial infarction (STEMI), left anterior descending (LAD) artery occlusion, otherwise normal coronaries, without significant co-morbidities and 16 comparable subjects with stable ischemic heart disease and lesion in LAD. Blood samples from coronary sinus (CS) and aorta (Ao) were drawn before percutaneous intervention (PCI), immediately after and at the end of the procedure. Venous blood from 30 healthy volunteers served as control.
Results: STEMI patients presented high IL-6 concentrations that increased further after reperfusion when its levels in CS became significantly higher than in Ao. In both groups prior to the PCI there were significantly higher concentrations of sIL-6R in Ao than in CS. This difference disappeared immediately after reperfusion. STEMI patients who experienced cardiovascular complications had higher IL-6 concentration and higher transcardiac sIL-6R gradient than patients with event-free hospitalisation. This association was confirmed in multivariate logistic regression analysis. Myocardial infarction increases concentration of IL-6 that is further elevated by reperfusion. A transcardiac gradient of sIL-6R during ischemia may indicate that large amounts of soluble IL-6 receptors are bound to the infarcted heart and thus affect signal transduction. IL-6 and initial sIL-6R gradient may portend complications in STEMI patients.