Inhibiting DNA Methylation by 5-Aza-2′-deoxycytidine Ameliorates Atherosclerosis Through Suppressing Macrophage Inflammation

Abstract

Inflammation marks all stages of atherogenesis. DNA hypermethylation in the whole genome or specific genes is associated with inflammation and cardiovascular diseases. Therefore, we aimed to study whether inhibiting DNA methylation by DNA methyltransferase inhibitor 5-aza-2-deoxycytidine (5-aza-dC) ameliorates atherosclerosis in low-density lipoprotein receptor knockout (Ldlr / ) mice. Ldlr / mice were fed an atherogenic diet and adminisered saline or 5-aza-dC (0.25 mg/kg) for up to 30 weeks. 5-aza-dC treatment markedly decreased atherosclerosis development in Ldlr / mice without changes in body weight, plasma lipid profile, macrophage cholesterol levels and plaque lipid content. Instead, this effect was associated with decreased macrophage inflammation. Macrophages with 5-aza-dC treatment had downregulated expression of genes involved in inflammation (TNF-, IL-6, IL-1, and inducible nitric oxidase) and chemotaxis (CD62/L-selectin, chemokine [C-C motif] ligand 2/MCP-1 [CCL2/MCP-1], CCL5, CCL9, and CCL2 receptor CCR2). This resulted in attenuated macrophage migration and adhesion to endothelial cells and reduced macrophage infiltration into atherosclerotic plaques. 5-aza-dC also suppressed macrophage endoplasmic reticulum stress, a key upstream signal that activates macrophage inflammation and apoptotic pathways. Finally, 5-aza-dC demethylated liver X receptor (LXR) and peroxisome proliferator-activated receptor 1 (PPAR1) promoters, which are both enriched with CpG sites. This led to overexpression of LXR and PPAR, which may be responsible for 5-aza-dC's antiinflammatory and atheroprotective effect. Our findings provide strong evidence that DNA methylation may play a significant role in cardiovascular diseases and serve as a therapeutic target for prevention and treatment of atherosclerosis. (Endocrinology 155: 4925-4938, 2014) M acrophage inflammation plays a significant role in atherogenesis. A hallmark of atherosclerosis is the infiltration of macrophages into the arterial wall, which promotes atherosclerotic plaque formation, progression, and rupture (1, 2). The early development of atherosclerosis involves adhesion of monocytes to activated endothelial cells by vascular cell adhesion molecule 1. The chemokine monocyte chemoattractant protein 1 (MCP-1)