Abstract 16013: Annexin-A1 Interacts With NF-KappaB Inhibiting Its Activation: Cardioprotection in vivo and in vitro
Background: Annexin-A1 (ANXA1), a mediator of the anti-inflammatory action of glucocorticoids, is cardioprotective in multiple preclinical models of myocardial ischemia-reperfusion (I/R), but underlying mechanisms are incompletely understood. We tested the hypothesis that direct association between ANXA1 and NF-κB p65 results in attenuation of NF-κB activation and promotes cardiomyocyte survival in the setting of myocardial I/R.
Methods: Rat in vivo I/R: Male Sprague-Dawley rats underwent 60 min of DHCA (deep hypothermic circulatory arrest) at 18°C followed by 6h of reperfusion, and received either vehicle or an ANXA1-mimetic tripeptide (ANXA1sp, 2mg/kg, iv) 1 h before and 1 h post reperfusion. In vitro simulated I/R: adult rat ventricular cardiomyocytes (ARVCs) were pre-incubated with either dexamethasone (DEX, 3 μ M), ANXA1sp (30 μ M), or ANXA1-siRNA, and subjected to 2h oxygen-glucose deprivation followed by 1h reoxygenation. Assays conducted in both ventricular myocardium and ARVCs: association between ANXA1 and NF-κB p65 (confocal colocalization); NF-κB DNA binding activity, cytokines, myocardial myeloperoxidase (MPO), necrosis markers - TnI, HFABP (ELISA); apoptosis (TUNEL); ANXA1, caspase-3 (Western blot).
Results: DEX and ANXA1sp induced expression of ANXA1 in vitro and in vivo. Following both treatments, ANXA1 associated with NF-κB p65 and suppressed its activation, accompanied by downstream inhibition of TNFα and IL-6, reduction of myocardial MPO, as well as significant attenuation of ARVC/myocardial necrosis and apoptosis. Conversely, siRNA knockdown of ANXA1 resulted in enhanced cardiomyocyte NF-κB activity and apoptosis (Figure).
Conclusions: We report a novel functional association between ANXA1 and NF-κB p65, which confers cardioprotective effects through resolution of myocardial inflammation following global I/R, suggesting the possibility of mechanism-driven drug development for perioperative cardioprotection.
- © 2011 by American Heart Association, Inc.