Abstract P1116: Early Life Stress Induces HDAC-Dependent Expression of Pro-Oxidant Genes in the Aorta

Abstract

Childhood adversity or early life stress (ELS) is an understudied risk factor for cardiovascular disease (CVD). The mouse ELS model, maternal separation with early weaning (MSEW), generates robust effects on anxiety as well as immunological consequences in adulthood. Previous studies from our laboratory showed that MSEW induces a pro-oxidant vascular phenotype in adulthood. Early in life or during development, epigenetic mechanisms such as the cellular balance of histone acetylation and deacetylation (HDACs) critically influences gene expression. We hypothesized that MSEW induces HDAC-dependent expression of pro-oxidant genes in the vasculature. Thoracic aortae were isolated from male adult (12 wk) normally-reared (NR) or MSEW mice. Histone 3 lysine acetylation (H3K27) status was found to be significantly decreased in aorta from MSEW compared to NR mice, indicating MSEW induced increased HDAC activity. The MSEW-induced increased in aortic NADPH oxidase (NOX) 2, NOX4, and toll-like receptor (TLR) 4 expression and was significantly blunted with ex vivo trichostatin A (TSA) treatment with no changes in NR mice (relative mRNA; NOX2: MSEW+VEH 1.55±0.12 vs MSEW+TSA 1.24±0.16, NOX4: MSEW+VEH 1.68±0.14 vs MSEW+TSA 1.25±0.07, TLR4: MSEW+VEH 1.65±0.16 vs MSEW+TSA 0.79±0.09, N=4-8, p<0.05). Further, MSEW-induced endothelial dysfunction was reversed with ex vivo TSA treatment with no changes observed in NR mice (E max NR+VEH 86.3±3.5, NR+TSA 82.8±6.3, MSEW+VEH 64.1±8.2 vs MSEW+TSA 85.9±1.7, N=8-12, p<0.05). Reports show that HDAC9 is associated with increased risk for vascular diseases. Aorta from MSEW mice had a significant increase in HDAC9 abundance compared to NR mice (rel. mRNA; NR: 1.02±0.1 vs MSEW: 1.67±0.2, N=6, p<0.05). To determine whether HDAC9 directly induces NOX2, NOX4, and/or TLR4 expression, we utilized HDAC9 over-expressing (HDAC9-OE) mice. Aortic tissue from HDAC9-OE mice revealed a 10-fold NOX4 and 13-fold TLR4 increase, with no change in NOX2 expression. Our results indicate that HDACs, especially HDAC9, are ELS-sensitive mediator(s) of pro-oxidant gene expression. We conclude, that activation of HDAC-dependent pro-oxidant genes, specifically NOX4 and TLR4 pathways, contribute to increased CVD risk following ELS.