Prevention of cardiac reperfusion injury following global ischemia by a monoclonal antibody, R2-1A6

Neutrophil-independent myocardial dysfunction during an early stage of global ischemia and reperfusion of isolated hearts

The effect of global ischemia and reperfusion on the expression of cytokine genes and cell adhesion molecules by myocardial tissues and neutrophils was studied by using the Langendorff model. Although cardiac function deteriorated after reperfusion of ischemic hearts, there was no evidence of inflammation and myocardial degeneration, which is in contrast to previous findings that neutrophil-mediated inflammation is a critical step in post-ischemic reperfusion injury in regional ischemia. Flow cytometry analysis demonstrated that the global ischemia and reperfusion did not affect the expression of adhesion molecules on neutrophils. We also examined the expression of various cytokines which are involved in inflammatory responses. Only interleukin 1 alpha was induced after the reperfusion of the ischemic hearts. These results suggest that neutrophils barely contribute to the myocardial dysfunction and IL-1 alpha may play a role in post-ischemic myocardial dysfunction during the early stage of reperfusion.

Protective effect of monoclonal antibodies against LFA-1 and ICAM-1 on myocardial reperfusion injury following global ischemia in rat hearts

The effects of anti-LFA-1 and anti-ICAM-1 monoclonal antibodies (MAbs) on the reperfusion injury of rat cardiac tissues after global ischemia were studied. Studies were performed using an isolated blood perfused heart preparation in which hearts were subjected to 30 min of global ischemia followed by 40 min of reperfusion. Isolated rat hearts were perfused with blood from an anesthetized support rat with or without anti-LFA-1 or anti-ICAM-1 monoclonal antibody administration (n = 10 in each group). Ventricular function, myocardial tissue water content and myocardial energy status were evaluated in this model. In the control group, ischemia and reperfusion of isolated hearts resulted in a 63.6 +/- 2.7% recovery of left ventricular developed pressure (LVDP) and a 44 +/- 7% increase in coronary vascular resistance compared with pre-ischemic baseline values. Treatment with anti-LFA-1 MAb or anti-ICAM-1 MAb resulted in a 77.2 +/- 1.5% and a 80.4 +/- 3.0% recovery of LVDP, respectively. In addition, increase in coronary vascular resistance was only 23 +/- 7% and 13 +/- 6% in anti-LFA-1 and anti-ICAM-1-treated groups, respectively. Values are significantly different between the control group and MAb-treated groups. Ischemia and reperfusion resulted in a 16% increase of myocardial tissue water content (3.71 +/- 0.03 in pre-ischemic baseline versus 4.29 +/- 0.08 ml/g dry weight) in the control group, whereas that resulted in only 3.0 and 5.7% increase in anti-LFA and anti-ICAM-1-treated groups, respectively. The difference between the control group and MAb-treated groups was significant. Cardiac energy status as assessed by adenosine triphosphate (ATP) concentration was markedly reduced in the control group at 40 min of reperfusion compared with pre-ischemic baseline values (5.70 +/- 0.27 vs. 14.92 +/- 0.48 mumol/g dry weight). In contrast, the reduction of myocardial ATP concentration at 40 min of reperfusion was significantly inhibited by anti-LFA-1 and anti-ICAM-1 monoclonal antibody treatment (5.70 +/- 0.27 vs. 8.96 +/- 0.52 and 8.10 +/- 0.47 mumol/g dry weight, respectively). These results suggest that a LFA-1/ICAM-1 pathway plays a critical role in the pathogenesis of postischemic myocardial injury during early reperfusion period.