DNA甲基化在ApoE-/-小鼠動脈粥狀硬化發育程序化之角色

心臟疾病高居國人的十大死因之一，其中冠狀動脈心臟病則是動脈粥狀硬化變性最容易引起的一個疾病。動脈粥狀硬化一般認為是脂質代謝失調引起的慢性發炎疾病，除了後天飲食攝取的因素外，基因遺傳和表觀遺傳修飾皆與動脈粥狀硬化的成因有關。發展規劃 (Developmental programming)提出在胚胎或胎兒的發育關鍵時期會受到母體環境影響，從而決定成年後的生理功能和代謝反應。實驗室的先前研究得知，母鼠暴露於西方飲食誘導高膽固醇血症的情況下所生出的子代較易發展動脈粥狀硬化，且其中的機制與改變DNA甲基化修飾有關。故本實驗藉由在親代母鼠施打 DNA 甲基轉移酶抑制劑 5-Aza-2’- deoxycytidine (5-Aza-dC)，探討是否能透過胎兒規劃調控 DNA 甲基化的程度而改變子代動脈粥狀硬化。本實驗動物模式使用ApoE-/- 小鼠，親代母鼠餵食Control diet (CD)且隨機分組，在孕前以及哺乳期階段分別施打PBS 或5-Aza-dC至子代離乳總計七週，而後生下的子代統一餵食 Western diet (WD)誘導高血脂加速動脈粥狀硬化形成，子代小鼠根據母鼠飲食和施打藥物分成 (1) PBS+ CW 及 (2) 5-Aza-dC + CW兩組。我們發現與 PBS+ CW 組相比，5-Aza-dC + CW 組子代雄鼠動脈粥狀硬化的程度有減緩的情況，且主動脈中有較低巨噬細胞相關基因表達，並在周邊血免疫細胞發現促發炎單核球和巨噬細胞比例顯著下降。此外，在骨髓衍生巨噬細胞中發現，親代母鼠施打 5-Aza-dC 會減緩子代雄鼠M1巨噬細胞分泌促發炎細胞因子TNF-α，另外M1以及M2 巨噬細胞相關基因表達也皆較低。總結，我們發現親代母鼠處理 5-Aza-dC，會使子代雄鼠罹患動脈粥狀硬化病症的風險下降，其中可能的機制之一為透過減少巨噬細胞的分化和/或活化路徑。

關鍵字

動脈粥狀硬化；表觀遺傳； DNA甲基化；胎兒規劃；巨噬細胞極化分化

並列摘要

Cardiovascular disease is the leading cause of death worldwide, and it is usually caused by atherosclerosis. Atherosclerosis is considered as a chronic inflammatory disease, and involves lipid metabolism disorder. Numerous epidemiological and experimental studies demonstrate that adverse influences during fetal life and/or early development program an increased risk for cardiovascular disease in later life. Our previous studies showed that female offspring born to hypercholesterolemic dams had accelerated progression of atherosclerotic lesions, and alterations of DNA methylation was involved. Here we investigate whether maternal treatment of DNA methyltransferase inhibitor (5-Aza-2’-deoxycytidine, 5-Aza-dC) has impact on the development of atherosclerosis in adult offspring. In this study, ApoE-/- female mice fed a control diet (CD) were given PBS or 5-Aza-dC before pregnancy and during lactation, and all offspring were fed a WD after weaning. Two groups of offspring,PBS + CW and 5-Aza-dC + CW were generated. We showed that maternal 5-Aza-dC treatment significantly reduces atherosclerotic lesions size and reduced expression of macrophage related genes in the aorta of male offspring. We also showed that circulating Ly6Chigh monocyte and F4/80 macrophage counts were markedly decreased in 5-Aza-dC + CW group compared to PBS + CW group. Using ex vitro culture of bone marrow-derived macrophages, we showed that maternal 5-Aza-dC treatment suppressed M1 macrophage polarization and inhibited the secretion of the proinflammatory cytokine TNF alpha in M1 macrophages. In addition, the expression of M2 macrophage-related genes was reduced in M2 macrophages of 5-Aza-dC + CW group compared to those of PBS + CW group. Collectively, we showed that maternal 5-Aza-dC treatment ameliorated the progression of atherosclerosis in male offspring, which may be attributed to alterations in macrophage differentiation/activation status.