Background: Therapeutic myocardial angiogenesis is an important compensatory mechanism in severely coronary stenosis. Previous studies demonstrated that interleukin-8 (IL-8) not only plays an important role in inflammation, but also a potent angiogenic factor through p38 mitogen-activated protein kinase (p38MAPK), nuclear factor-kappaB (NK-κB)-dependent pathway in carcinoma. Our study sought to investigate the effects of IL-8 on the angiogenesis and the underlying mechanism in the ischemic myocardium.
Methods: Acute myocardial infarction animal model was established with male rabbits by directly suturing the left anterior descending branch, then lentivirus-mediated IL-8 was quarterly injected into the borderline of infarction area immediately. We employed CoCl2 induced hypoxic HUVECs for in vitro ischemia study. Left ventricular end-diastolic diameter (LVEDd) and ejection fraction (EF) were measured by echocardiography in pre-operation and at 6(th) week after operation. CD34 was detected with immunohistochemisty to analyse angiogenesis. Western blot was performed with regard to IL-8, protein kinase B (PKB/Akt) and Glycogen synthase kinase-3β(ser9) (GSK-3β(ser9)). For the HUVECs' proliferation and apoptosis, multiscan spectrum reader at A570 nm and annexin V-FITC/PI staining method were used respectively.
Results: The levels of IL-8, phosphorylated Akt and GSK-3β(ser9) in focal myocardium significantly increased, and the over expression of IL-8 led to an increasing in angiogenesis in rabbits. Hypoxia inhibited cell proliferation and promoted apoptosis. IL-8 induced cell proliferation, phosphorylation of Akt and GSK-3β(ser9), inhibited apoptosis and Caspase3 expression in HUVECs, which were attenuated by anti-IL-8 or the Akt inhibitor LY294002.
Conclusions: The present results indicate that IL-8 can increase angiogenesis in myocardial infarction, which maybe through enhancing Akt and GSK-3β(ser9) expression, and inhibiting myocardial apoptosis.
Keywords: Akt/GSK-3βser9 pathways; IL-8; angiogenesis; ischemic myocardium.