抗菌剂三氯生对胚胎心肌发育的影响及其表观遗传机制

Among all birth defects, congenital heart disease (CHD) is the most prevalent and remains the leading cause of death. In most cases the causes of CHD remain unknown, while a growing number of studies have indicated the potential role of environmental agents as risk factors in CHD occurrence. Triclosan (TCS), as broad spectrum antibacterial agents, is widely used in personal care products (PCPs) and has been one of the most frequently detected chemicals in the environment and humans. Our previous study found that TCS could affect the fetal heart development, but the mechanism is still unclear. In the present study, the human embryonic stem cell (hESC)-derived cardiomyocytes are used as a model of the early stages of heart development to determine the developmental toxicity of TCS. Morphology of cardiomyocytes, the percentage of beating EBs, genes and proteins related to cardiac development are examined and compared between TCS-treated cells and the control cells. To explore the mechanism involved in TCS’ cardiac toxicity, we investigated the DNA methylation and histone acetylation patterns between the treatment and control groups. This may provide greater insight into the epigenetic mechanism of TCS on cardiogenesis and help to identify biological markers for risk assessment of EDCs exposure causing CHD. In addition, hESC-derived cardiomyocytes will be used as an excellent model system for screening for developmental toxicity of environmental chemicals. It may provide evidence for the prevention of CHD and make contributions to improve the quality of the population and children's health.

先天性心脏病是首位高发出生缺陷，严重危害婴幼儿健康，其病因复杂，其中环境化学物是一种重要的致病因素。抗菌剂三氯生（TCS）广泛应用于个人护理品中，在环境和生物体中大量累积，我们前期研究发现TCS会影响胚胎心脏发育，但作用机制不明。本项目拟采用人胚胎干细胞定向分化的心肌细胞为模型，从心肌细胞形态学、分化程度、心肌关键基因和蛋白表达上论证TCS的心肌毒性。从DNA甲基化、组蛋白乙酰化方面，揭示TCS的关键调控靶点和作用方式，阐述其影响干细胞向心肌细胞分化过程的表观遗传机制，发现化学物暴露致先心病的候选生物学标志。本项目还有利于将干细胞定向心肌细胞分化模型应用于评价环境化学物的心肌发育毒性，为先心病的防治提供依据，为提高人口质量、促进儿童健康做出贡献。

先天性心脏病（CHD）是首位高发的出生缺陷，其病因复杂，其中环境化学物是重要的致病因素。抗菌剂三氯生（TCS）广泛应用于个人护理品中，大量累积在环境和生物体中，我们前期研究发现TCS会影响胚胎心脏发育，但作用机制不明。本项目采用人胚胎干细胞H9定向分化的心肌细胞为模型，用相当于环境暴露剂量的1µM TCS，从心肌细胞形态学、分化程度、心肌细胞自主搏动速率、心肌特异性基因和蛋白表达上，揭示TCS对H9向心肌细胞分化过程的影响。从转录组表达、DNA去甲基化和甲基化相关酶表达、全DNA甲基化状态、组蛋白乙酰化方面，揭示TCS的关键调控靶点和作用方式，阐述其影响干细胞向心肌细胞分化过程的表观遗传机制。结果表明TCS可以导致人胚胎干细胞向心肌细胞的分化率降低、心肌细胞的自主搏动速率减少、心肌特异性基因和蛋白的表达水平降低，为TCS所致的心肌发育毒性提供表型依据。通过转录组分析和全甲基化检测研究，明确了TCS的关键调控位点，找到1203个差异甲基化区域，对差异DMR附近的基因进行注释，找出关联的差异基因DMR分布，明确了心肌分化关键因子对应的成组DMR作为TCS的效应标志物。通过对TCS暴露组和对照组的组蛋白乙酰化H3K27ac状态分析，找到关键差异区域，阐明了组蛋白乙酰化在TCS致胚胎心肌毒性中的分子机制。研究结果有利于揭示TCS引起心肌发育毒性作用的早期敏感指标和分子机制，发现化学物暴露致CHD的候选生物学标志。本项目同时将干细胞定向诱导分化形成的心肌细胞模型作为一种化学物心肌毒性的有效评价体系，可以在环境化学物、药物等心肌毒性预测评估上得以推广应用，为CHD的早期预防提供理论依据。