Epigenetic Programming Reverses Cardiometabolic Dysfunctions and Modulates Hypothalamic Genes Involved in Oxidative Stress and Inflammation in Angiotensin II-Treated Male Mice

Abstract

Cardiometabolic disease is a global health issue that affects millions of people worldwide. Environmental perinatal exposure affects the health outcomes of the offspring and determines their disease susceptibility later in life. Angiotensin-II (Ang-II) is a peptide known to cause vasoconstriction, elevated blood glucose levels and inflammation. Previously, we reported that perinatal exposure to a hypercaloric diet (HD) results in elevated blood pressure (BP), weight gain, fasting hyperglycemia and glucose intolerance only in male mice. In addition, subcutaneous infusion of a sub-pressor dose of Ang-II was associated with a normalization in fasting blood glucose levels and a reversal of glucose intolerance only in programmed male mice. We hypothesize that epigenetic programming blocks the deleterious effects of Ang-II by altering its inflammatory signaling pathway. C57BL6/J dams were fed HD or regular diet (RD) for 1 month before mating with RD-fed males. After weaning, offspring of HD dams (programmed) and of RD dams (controls) were maintained on RD until 3 months of age. Mice then underwent 24 h BP recording (telemetry) and were implanted with Ang-II osmotic pumps (200 ng/kg/min/2 weeks). BP (24 h) was recorded weekly for 2 weeks. Mice were then sacrificed and hypothalami were harvested for mRNA sequencing (Illumina NextSeq). Programmed mice had lower 24 h systolic BP levels compared to control males (area under the curve: 41844 ±263.2 vs. 44522 ±275.6; p<0.0001). For RNAseq analysis, data showed 62 differentially expressed genes (DEG) in programmed males compared to controls. Using iPathway analysis, we found that some of the DEG are correlated to cholinergic synapse pathway (p=0.005) and neuroactive ligand-receptor interaction pathway (p=0.003). Nicotinic acetylcholine alpha-7 receptor (Chrna7) gene, known for its anti-inflammatory and hypoglycemic effects was upregulated in programmed males (p=0.024). On the other hand, genes involved in metabolic pathways and oxidative stress were differentially expressed as well. Phospholipase A2 group 3 (Pla2g3) gene, known to be overexpressed in oxidative stress was downregulated in programmed males (p=0.04). Moreover, Thiosulfate sulfurtransferase (Tst) gene, an antioxidant enzyme and used as a marker for enhanced insulin sensitivity was upregulated (p=0.023) in programmed males. Interestingly, female mice did not show any changes in BP or gene expression between the two groups. In conclusion, perinatal exposure to HD alters the cardiovascular response to Ang-II possibly through the modulation of gene expression of Chrna7 gene and genes involved in oxidative stress. Future experiments will be investigating the signaling pathways used in epigenetic programming to affect inflammation and oxidative stress in male mice.