Abstract 13329: Intralipid Protects the Heart in Late Pregnancy Against Ischemia/Reperfusion Injury via Inducing Mir122 by Targeting Pkm2

Abstract

INTRODUCTION: We have shown hearts of late-pregnant (LP) rats have higher vulnerability to ischemia-reperfusion injury (IRI) compared to non-pregnant (NP) rats, and administration of intralipid (ITLD), a clinically safe fat emulsion, at the onset of reperfusion protects the LP rat heart against IRI. Our goal is to decipher the mechanisms for the ITLD-mediated cardioprotection in LP against IRI. Methods: We occluded the left anterior descending coronary artery of female Sprague-Dawley rats (2-3 months old NP and LP, 20-21 days pregnant) for 45 minutes followed by 3 hours reperfusion. The ITLD group was given ITLD at the onset of reperfusion (5mg/kg of 20%). We assessed myocardial necrosis via TTC staining and sent the hearts for microRNA-microarray profiling (Ocean Ridge Biosciences). In vitro, female cardiomyocytes were transfected either miR122 mimic, miR122 inhibitor, or scramble control (40uM), followed by 3 hours hypoxia and 6 hours reoxygenation. We collected human blood samples from NP, LP, and LP coronary heart disease (CHD) patients. P<0.05 was considered statistically significant. Values are expressed as mean±SEM. Results: MicroRNA-microarray profiling showed microRNA-122-5p (miR122) is downregulated 4-fold in the heart of LP rats subjected to IRI compared to healthy pregnant rats and upregulated 10-fold in the heart of LP rats that received ITLD at reperfusion, which we confirmed with qPCR (0.32±0.12, 90.2±10.3, n=5 animals/group). miR122 is significantly decreased in the plasma of healthy LP women compared to healthy NP women (0.6±0.16, LP n=9, NP n=7) and decreased in LP women with CHD compared to healthy LP (0.43±0.13, CHD n=5). TargetScan showed PKM2 to be a target of miR122. We confirmed significantly increased PKM2 in LP IRI rat myocardium compared to NP IRI (1.88±0.32) and significantly decreased in LP IRI rat administered ITLD (0.32±0.18). MiR122 overexpression in female cardiomyocytes subjected to hypoxia/reoxygenation (H/R) significantly decreased PKM2 (0.35±0.12), apoptosis (0.77±0.12) and oxidative stress (0.51±0.12), while miR122 knockdown expressed the opposite effect (n=4). Conclusions: Intralipid protects the heart in late pregnancy against ischemia/reperfusion injury by upregulating miR122, which targets PKM2.