漆黄素纳米粒抑制iRhom2/NF-κB信号通路改善PM2.5导致的中枢炎症研究

Increasing studies have given the fact that air pollution (PM2.5) contributes to the occurrence of nerve injury and metabolic syndrome. However, there is no direct testimony of this, and yet the molecular mechanism by which the occurrence remains unclear, and also has no effective chemoprevention. Thus, based on our previous contribution, the assumption named “Fisetin nanoparticles restrain PM2.5-induced central nervous inflammation and metabolic syndrome by inhibition of iRhom2/NF-κB signaling pathway” was presented for this issue. .First of all, the role of iRhom2 in PM2.5-induced mice hypothalamus inflammation and metabolic disorder was determined. We next attempt to show the pathway of iRhom2/NF-κB may primarily contribute to astrocytes activation and nerver injury. Then, created fisetin nanoparticles was used to confirm whether and how to suppress iRhom2 expression and its down-stream pathway iRhom2/NF-κB activation. For peripheral metabolism examination, analysis of blood pressue, glucose, body weight, daily ration, insulin level, inflammatory cytokines expression, activated astrocytes and lipid metabolism related indicators were performed in PM2.5-induced mice. Inflammatory infiltration in liver, kidney and spleen was examined, in order to evaluate the possibly protective effect of nanofisetin on peripheral inflammation caused by PM2.5 administration. Then, we pay more attention to detect a series of important factors such as iRhom2，TACE，NF-κB，POMC，AgRP，NPY and MC4r expression in PM2.5-induced nerve injury and astrocytes activation; and indicate the inhibitory mechanism of nanofisetin on hypothalamus inflammation. Subsequently, inhibition in enhanced iRhom2/NF-κB was confirmed by siRNA target to iRhom2 gene, which was treated as major signaling pathway contributs to nerve injury and astrocytes activation in hypothalamus..If successful this proposal will develop a novel molecular mechanism by which nanofisetin may suppress PM2.5-induced nerve injury and metabolic syndrome; and enrich application of fisetin as food additives in light industry.

PM2.5诱导神经损伤和代谢综合征已被证实，但机制尚不明确，化学预防手段匮乏。基于本课题组前期工作，本项目提出漆黄素纳米粒抑制iRhom2/NF-κB信号缓解PM2.5导致的下丘脑神经炎症和代谢综合征假说。拟在PM2.5暴露的小鼠模型上，先证实iRhom2基因为下丘脑炎症发生的主要触发机关，iRhom2/NF-κB为PM2.5诱导神经炎症的关键信号。再分析漆黄素干预对实验动物体重、摄食量、外周炎症因子、糖和脂代谢相关指标的影响；观察评价其对外周脏器炎性浸润改善作用。着重研究漆黄素干预对下丘脑炎症导致神经元损伤和星形胶质细胞激活相关信号关键因子iRhom2、NF-κB、GFAP和黑皮质素信号关键分子POMC及MC4r的调节作用。解析其逆转中枢下丘脑炎症介导外周代谢紊乱与PM2.5暴露的内在关系，并以转基因法干预体外细胞炎症模型来验证结果、佐证假说。以期阐明漆黄素改善下丘脑神经炎症的作用机制。

PM2.5诱导神经损伤和代谢综合征已被证实，但机制尚不明确，化学预防手段匮乏。本项目创新性地采用自然环境模拟器模拟真实环境中PM2.5浓度和实验动物生活环境，同时结合分子生物学、荧光共聚焦、动物行为学、免疫共沉淀等研究手段，在PM2.5诱导的下丘脑神经损伤和外周早期肝脏细胞损伤相关的非酒精性脂肪肝（NAFLD）发生水平上研究了PM2.5诱导下丘脑神经炎症发生和罹患NAFLD的潜在风险的分子机制以及漆黄素纳米粒的改善作用。发现：（1）PM2.5长期暴露显著诱导实验小鼠全身性代谢综合征的发生，包括高胰岛素血症、高瘦素血症、NAFLD等疾病；（2）PM2.5暴露诱发实验动物下丘脑神经元萎缩、下丘脑黑皮质素（POMC）神经元及其受体（Mc4R）损伤及传递障碍以及星形胶质细胞（AST）活化；（3）iRhom2因子是PM2.5诱发的下丘脑炎症发生的主要触发机关，iRhom2/NF-κB信号轴是PM2.5诱导神经炎症的关键信号；（4）稳定合成了基于金-铁核壳结构荷载的漆黄素纳米粒，显著提高了其生物利用率、水溶性以及稳定性；(5) 漆黄素改善PM2.5诱发的血脂代谢异常、高瘦素血症、肝脏脂肪性病变等，减少下丘脑POMC神经元功能和Mc4R的损伤；(6) 漆黄素抑制下丘脑神经炎症、GFAP蛋白高表达和iRhom2/NF-κB信号活性，同时减少AST的异常活化；(7) 拓展研究还发现，活化的iRhom2招募下游TAK1蛋白，促进其磷酸化水平的增加，显著增加NF-κB相关的炎性因子的表达水平，进一步诱导实验动物外周胰岛素抵抗、肝脏脂质积累相关的NAFLD疾病、脂肪组织炎症和慢性肾脏损伤等。上述结果证实PM2.5诱导的iRhom2/NF-κB信号活化相关的下丘脑神经炎症是导致神经元损伤，并引起肥胖、高血压、高血脂症、NAFLD等代谢性疾病发生的关键因素；揭示抑制iRhom2可能成为缓解下丘脑神经炎症，保护神经元，改善PM2.5诱导的代谢综合征的新途径。相关成果已经发表于Hepatology，Redox Biology，Journal of Hazardous Materials，Advanced Healthcare Materials，Molecular Metabolism，Free Radical Biology and Medicine等中科院1区刊物。