High mobility group box 1 levels in on and off-pump cardiac surgery patients

High mobility group box 1 (HMGB1), which has properties similar to those of proinflammatory cytokines, is released from activated immune cells and necrotic cells. It is known that cardiopulmonary bypass (CPB) induces systemic inflammation and aortic cross-clamping induces myocardial ischemia. This study was conducted to clarify whether HMGB1 is released in CPB-supported cardiac surgery in comparison to off-pump coronary artery bypass grafting (OPCAB) where CPB is not used.Nineteen adult patients undergoing cardiac surgery involving CPB (CPB group) and 5 OPCAB patients (OPCAB group) were included in this study. Plasma concentrations of proinflammatory cytokines including HMGB1 were measured before, during, and after cardiac surgery. The plasma HMGB1 level was significantly increased at one hour after aortic declamping in the CPB group and at 30 minutes after revascularization in the OPCAB group. The peak HMGB1 level was slightly higher in the CPB group than that in the OPCAB group. These values decreased toward baseline value after surgery in both groups. TNF-α and IL-1β were not detectable throughout the study period in either group. IL-6 and IL-10 increased after aortic declamping in the CPB group and after coronary revascularizations in the OPCAB group.Based on these results, we conclude that the major factor involved in the increase in HMGB1 level might be myocardial ischemia/reperfusion during cardiac surgery. Activation of immune cells, altered tissue perfusion, and pulmonary ischemia and reperfusion could be additional factors that increase the HMGB1 level in CPB-supported cardiac surgery.