DEHP/乙醇基于PPARα/γ信号通路致肝脏损伤的联合毒性效应研究

As one of the most common type of plasticizer in food contaminants, di(2-ethylhexyl)phthalate (DEHP) is of potential liver toxicity and has imposed serious threat on food safety and human health. Ethanol and DEHP both toxicologically targeted liver and share similar mode of actions based on peroxisome proliferators-activated receptors (PPARs) signaling pathway. Hence the joint exposure to the two chemicals may generate combined toxicity in liver. Currently, toxicological studies regarding their co-exposure are very rare, and the food safety risk assessment according to the toxicity of DEHP alone would probably underestimate the overall health effect in actual cases. Our preliminary study showed that the combined exposure of DEHP and ethanol could enhance the hepatotoxicity as well as PPAR response in comparison with those under single exposure. Therefore, we hypothesized that "DEHP and ethanol synergize the toxicological effects on liver through PPARα/γ signal pathway under co-exposure." This project is to validate the combined toxicity of DEHP and ethanol by chronic oral toxicity test in animals and in vitro test in human primary hepatocytes. In addition, the knockout animal (PPARα/γ- null) models, RNAi and PPARα/γ-overexpression cell models will be used to investigate the underlying mechanisms by which DEHP and ethanol jointly induce hepatic lesions via PPARα/γ toxicity pathway. The results are expected to provide scientific basis for the food safety risk assessment of joint exposure of plasticizer and alcohol in the human diet.

邻苯二甲酸二(2-乙基己)酯（DEHP）具有潜在的肝脏毒性效应，由于DEHP和乙醇的毒性作用靶器官均为肝脏，且具有相似的基于过氧化物酶体增殖物激活受体（PPARs）细胞信号通路的毒性作用方式，因此同时暴露时可能会发生联合毒性作用。目前关于二者联合暴露毒性研究极其缺乏，单纯根据DEHP毒性研究结果进行食品安全风险评估可能会低估该类物质对人群健康的总体影响。本实验室初步研究已经提示二者联合暴露可能增加单一暴露条件下的肝脏损伤及PPAR反应活性。因此，我们提出研究假说“DEHP和乙醇联合暴露能够通过PPARα/γ信号通路对肝脏产生协同毒性效应”。本项目拟通过动物试验、肝细胞体外试验研究验证DEHP和乙醇对肝脏的联合毒性作用，并通过基因敲除动物模型、RNAi和PPARα/γ超表达细胞模型阐明PPARα/γ毒性通路在肝脏毒性损伤中的作用机制，从而为增塑剂与乙醇联合暴露的食品安全风险评估提供依据。

邻苯二甲酸二(2-乙基己)酯（DEHP）作为食品中常见的增塑剂类污染物，具有明确的肝脏毒性效应，但作用机制尚不明确。乙醇和DEHP毒性作用靶器官均为肝脏，两类物质同时暴露时可能会发生联合毒性作用，目前关于二者联合暴露的毒性研究极其缺乏。本项目开展了动物试验研究DEHP/乙醇慢性经口暴露致小鼠肝脏损伤的联合毒性效应，通过转录组学分析及体外人源肝细胞试验验证了PPARG信号通路在肝脏损伤中的作用，而且对巨噬细胞在肝脏脂肪代谢中的作用进行了初步探讨。研究发现，DEHP经口暴露能够导致小鼠肝脏脂质代谢异常及其在肝脏中的堆积；转录组学分析表明，PPAR信号通路在DEHP诱导肝脏脂质代谢异常过程中具有关键作用，能够通过调节脂肪合成、脂质摄取、脂肪酸氧化等相关基因表达促进肝脏脂质堆积；PPARG基因敲除可能通过上调CD36等脂质摄取蛋白而增加了肝脏脂质堆积；此外，肝脏细胞PPARG失活可能促进炎性单核细胞趋化及M2型分化，从而促进肝脏细胞能量代谢异常。值得注意的是，DEHP/乙醇联合暴露虽未显著增加小鼠肝脏重量，但脂质代谢方面存在差异；联合暴露在人肝细胞中能够协同增加PPARG基因表达并抑制细胞凋亡，提示DEHP与乙醇的联合毒性可能存在动物种属差异。本课题研究未发现DEHP/乙醇联合暴露对肝脏具有显著的协同作用，但可能造成不同类型毒性效应对肝脏损伤的叠加；PPARG信号通路在DEHP诱发肝脏脂质代谢异常中具有关键作用，该基因表达及调控机制可能存在种性差异。本项目为评价人类膳食中增塑剂与乙醇联合暴露的食品安全风险评估提供科学数据，为DEHP诱发肝损伤的毒性效应机制研究提供了新的科学参考。