Abstract P429: Aldehyde Dehydrogenase 2 Regulates Angiogenesis Of Coronary Microvascular Endothelial Cells Via A Novel Signaling Pathway

Abstract

Coronary microvascular endothelial cell (CMECs) damage is implicated in diabetes-mediated heart failure with preserved ejection fraction (HFpEF). 4-hydroxy-2-nonenal (4HNE), a reactive aldehyde that is increased in diabetic heart, decreases angiogenesis in cultured mouse CMECs by decreasing the mRNA and protein levels of vascular endothelial growth factor receptor (VEGFR)2. Nuclear factor-kappa B (NF-kB), a transcription factor, was shown to transcribe VEGFR2. Thus, we presume 4HNE modulates NF-kB-mediated VEGFR2 transcription and regulates angiogenesis in CMECs. Aldehyde dehydrogenase (ALDH) 2, a mitochondrial enzyme that detoxifies 4HNE and confers cryoprotection. However, ALDH2 activity was reduced in the diabetic hearts which results in the augmentation of 4HNE-induced cardiotoxicity. Thus, we hypothesize that ALDH2 in CMECs reduces 4HNE-mediated cell signaling aberrations, and thereby, preserves coronary angiogenesis. We treated the cultured mouse CMECs with disulfiram (DSF) (2.5 μM), an ALDH2 inhibitor, alda1 (10 μM), an ALDH2 activator and prostratin (1 μM), an NF-κB activator prior to challenging the CMECs with 4HNE (75 μM). Our tube-formation angiogenesis assay revealed that pretreatment with DSF exacerbated a 4HNE-induced decrease in CMECs angiogenesis (P<0.0005 vs con and P<0.05 vs both 4HNE & DSF alone) while pretreatments with alda1 and prostratin attenuated a 4HNE-induced decrease in CMEC angiogenesis (P<0.05 vs 4HNE alone). DSF pretreatment exacerbated 4HNE mediated decrease in ALDH2 (P<0.005 vs con), phospho-IKBα (P<0.0005 vs con and P<0.05 vs both 4HNE and DSF alone), NF-κB levels, and nuclear translocation (P<0.0005 vs con and P<0.05 vs both 4HNE & DSF alone) and VEGFR2 (P<0.0005 vs con and P<0.05 vs both 4HNE and DSF alone) levels in cultured CMECs. Pretreatment with both prostratin and alda1 increased ALDH2 (P<0.0005 vs con), VEGFR2 (P<0.05 vs con) and NF-κB (P<0.005 vs con) levels in CMECs. The cardiac tissue samples of db/db mice when they manifest HFpEF showed increased 4HNE adducts, decreased NF-kB and VEGFR2 levels in CD31+ CMECs besides exhibiting low CMEC density. In conclusion, ALDH2 attenuates 4HNE-mediated decrease in coronary angiogenesis by decreasing VEGFR2 levels via low NF-κB mediated transcription.