Inhibition of IkappaB Phosphorylation in Cardiomyocytes Attenuates Myocardial Ischemia/reperfusion Injury

Objective: Reperfusion injury is related closely to inflammatory reactions such as activation of inflammatory cells and expression of cytotoxic cytokines. We investigated the efficacy of IkappaB phosphorylation blockade in a rat myocardial ischemia/reperfusion injury model.

Methods And Results: IMD-0354 inhibited phosphorylation of IkappaBalpha and nuclear translocation of nuclear factor-kappa B (NF-kappaB) induced by tumor necrosis factor-alpha (TNF-alpha) in cultured cardiomyocytes. TNF-alpha-induced production of interleukin-1beta and monocyte chemoattractant protein-1 from cultured cardiomyocytes was reduced significantly by IMD-0354. Transient left coronary artery occlusion (30 min) and reperfusion (24 h) were carried out in Sprague-Dawley rats. IMD-0354 (1, 5, 10 mg/kg) was injected intraperitoneally 5 min before the start of reperfusion. Treatment with IMD-0354 resulted in a significant dose-dependent reduction of the infarction area/area at risk ratio (vehicle, 47.0+/-3.4%; 10 mg/kg of IMD-0354, 19.4+/-4.0%; P<0.01) and the preservation of fractional shortening ratio (vehicle, 25.0+/-1.5%; 10 mg/kg of IMD-0354, 42.3+/-1.7%; P<0.01). Histological analysis showed that accumulation of polymorphonuclear neutrophils in the area at risk was decreased significantly.

Conclusions: Inhibition of nuclear translocation of NF-kappaB by IkappaBalpha phosphorylation blockade could provide an effective approach to attenuation of ischemia/reperfusion injury. The cardioprotective effects of IMD-0354 include not only reduction of harmful neutrophil accumulation in myocardium but also inhibition of harmful cytokine and chemokine production by cardiomyocytes.