双酚A增加脂肪组织巨噬细胞神经酰胺从头合成介导肥胖衍生的胰岛素抵抗及其机制

Long-term exposure to BisphenolA (BPA) , an universal environmental endocrin disrupting chemical, along with obesity is prominent risk factor of insulin resistance (IR), has become focus of public health at present. Studies have shown that BPA can promote IR resulted from obesity, but its underlying mechanisms remain unclear. Our previous studies showed that BPA can aggravate the decrease of insulin sensitivity, M1 type adipose tissue macrophages (ATMs) accumulated in adipose tissuein obese mice fed with high fat diet(HFD). As well as promote secretion of IL-1βthat interfered with insulin signaling in IR. Moreover, expression of sensor protein NLRP3 in NLRP3 inflammasome that molecular platform mediated IL-1βsecretion had upregulated in adipose tissue of BPA exposure obese mice fed with HFD. Combined with the last advancements of immunometabolism study, this program puts forward hypothesis that "BPA increases in ATMs-specific de Novo synthesis of ceramide promote NLRP3 inflammasome activation, hence aggravates IR resulted from obesity". Therefore, we will perform experiments through nlrp3-/- and sptlc2-/- gene knockout mice, specific antagonist and overexpression means in vivo combined with in vitro, to investigate the mechanism that increase in ATMs-specific de Novo synthesis of ceramide induced by BPA exposure，activates NLRP3 inflammasome through AMPK-ROS signaling pathway，then promote IL-1βsecretion and aggravate IR resulted from obesity. We also verify the hypothesis in population study. The results of this study will provide a new theoretical basis for the prevention and treatment of metabolic diseases associated with long-term exposure to BPA.

双酚A（BPA）长期暴露与肥胖同为胰岛素抵抗（IR）的主要危险因素及公共卫生关注热点。研究报道BPA可促进肥胖衍生的IR，但具体机制不清。课题组前期研究显示BPA促进HFD诱导肥胖小鼠脂肪组织ATMs聚集，增加干扰胰岛素信号的IL-1β分泌，且调控IL-1β分泌的NLRP3炎症体组分感受蛋白NLRP3表达上调，结合免疫代谢学最新研究进展，本课题提出“BPA增加肥胖诱发的ATMs内神经酰胺（Cer）从头合成，介导NLRP3炎症体激活，促进肥胖衍生的IR”的假设，利用nlrp3-/-和sptlc2-/-基因敲除小鼠、特异性拮抗剂和过表达等手段，采用动物实验结合体外研究探讨BPA增加肥胖诱发的ATMs内Cer从头合成，经MAPK-ROS通路激活NLRP3炎症体，上调IL-1β分泌，促进肥胖衍生的IR的机制，并用人群研究加以验证。研究结果将为环境BPA长期暴露相关的代谢性疾病防治提供新的理论依据。

过去几十年里全球代谢性疾病患病率急剧上升，严重威胁着人类健康，预防和控制代谢性疾病已成为当前公共卫生领域刻不容缓的任务。肥胖衍生的胰岛素抵抗（IR）是代谢性疾病的主要特征，同时也是代谢性疾病发生发展的驱动力。越来越多的证据表明，最常见环境内分泌干扰物双酚A（BPA）的大量生产和使用，造成人类广泛暴露是IR的重要危险因素。研究表明BPA暴露可促进肥胖衍生的IR，但具体机制不清。本项目基于免疫代谢学研究进展，通过动物实验阐明了BPA 暴露可增加小鼠脂肪组织巨噬细胞(ATMs)内神经酰胺（Cer）从头合成、NLRP3炎症体激活，促进肥胖衍生的IR；SPT抑制剂多球壳菌素明显抑制BPA暴露HFD喂养小鼠脂肪组织Cer从头合成限速酶SPTLC1表达上调和Cer含量上升，显著抑制BPA暴露HFD喂养小鼠体重增加，FG、FI和HOME-IR的升高，改善BPA暴露HFD喂养小鼠GTT和ITT，增强BPA暴露HFD喂养小鼠脂肪组织胰岛素敏感性。NLRP3抑制剂显著抑制BPA暴露HFD喂养小鼠体重增加，FG、FI和HOME-IR升高，改善BPA暴露HFD喂养小鼠GTT和ITT，增强BPA暴露HFD喂养小鼠脂肪组织胰岛素敏感性，抑制NLRP3炎症小体激活，揭示了BPA暴露增加小鼠 ATMs内Cer从头合成，激活NLRP3炎症体，促进肥胖衍生的IR机制；利用体外研究，通过AMPKα1 SiRNA和ROS拮抗剂实验，探讨了BPA暴露肥胖小鼠ATMs内合成的Cer经AMPK-ROS通路激活NLRP3炎症体的分子机制；采用病例对照研究，在人群水平验证了BPA暴露增加肥胖患者ATMs内Cer从头合成，激活NLRP3炎症体，促进肥胖衍生的IR。本项目的研究结果不仅阐明了BPA 暴露促进肥胖衍生的IR发生及代谢调控机制，还丰富了环境相关因子致代谢综合征的发病及调控机制，并为防治环境暴露的健康危害防治提供了全新的思路。