LncRNA PANDA调控巨噬细胞代谢重编程对动脉粥样硬化的影响及机制研究

Metabolic reprogramming of macrophages participate in the development of atherosclerosis. However, the molecular mechanism has not been fully elucidated. Recently, our studies demonstrate that proinflammatory macrophages (M1) stimulated by ox-LDL are vulnerable to present the mitochondrial dysfunction, which results in upregulating of ACAT-1 gene expression（a key enzyme responsible for cholesterol ester synthesis), downregulating of HSL and ABCA1 gene expression (key enzymes responsible for cholesterol lipolysis and efflux), and promoting the cholesterol accumulation in foam cells. Further studies identify for the first time that knockdown of PANDA has a protective effect on the mitochondrial function of macrophage, diminishes the expression of M1 phenotypes and promotes transition of macrophages to the M2 phenotype. Therefore we speculate that PANDA regulates metabolic reprogramming of macrophages, which in conjunction with changed ACAT-1, HSL and ABCA1 expression, works to have effect on the atherosclerosis development. Based on these results, using ox-LDL treated M1 and M2 macrophages as cell models and atherosclerotic ApoE−/− mice as animal models, we further explore the molecular mechanism of mitochondrial function, polarization phenotype and cholesterol ester metabolism regulated by PANDA in macrophages, so as to determine the role of PANDA in atherosclerosis. This study will provide an important theoretical basis for developing new anti-atherosclerotic drugs and establishing a new treatment strategy, and contribute to a novel molecular target for atherosclerosis.

巨噬细胞代谢重编程参与动脉粥样硬化(AS)发展进程，但具体机制尚不明确。我们前期预实验结果证实：促炎亚型M1型巨噬细胞受到氧化修饰的低密度脂蛋白（ox-LDL）刺激出现线粒体功能障碍，并上调胆固醇酯合成关键基因（ACAT-1）、下调脂解和外流关键基因(HSL、ABCA1)的表达，从而促进泡沫细胞形成。进一步研究首次发现：敲减PANDA可保护巨噬细胞线粒体的功能，抑制M1表型，促进巨噬细胞向抑炎亚型M2型转化。因此我们推测：PANDA可能通过调控巨噬细胞代谢重编程，来改变胆固醇酯合成、脂解和外流关键基因的表达从而影响AS的进展。本课题在此基础上设计，分别以ox-LDL干预的M1、M2型巨噬细胞为细胞模型，以ApoE基因敲除小鼠为AS动物模型，阐明PANDA调控巨噬细胞线粒体功能、极化表型和胆固醇代谢的分子机制，从这一全新的角度对PANDA进行研究，可为AS找到新的治疗靶点。

动脉粥样硬化（Atherosclerosis，AS）是一种慢性血管炎症性疾病，而与炎症发生关系最密切的细胞是单核/巨噬细胞。巨噬细胞的极化表型及其效应功能受到细胞内自身代谢水平变化的调控，即为巨噬细胞代谢重编程。M1型为促炎亚型，主要为无氧糖酵解和戊糖磷酸代谢途径供能，表现为：增加葡萄糖的利用和乳酸的释放，减少耗氧率（oxygen consumption rate，OCR）及线粒体氧化磷酸化（oxidative phosphorylation，OXPHOS）水平。而M2型为抑炎亚型，主要为氧化磷酸化供能，表现为：脂肪酸氧化水平明显升高。二者的分化影响着AS的发展结局。但巨噬细胞代谢重编程参与AS发展进程的具体机制尚不明确。.本课题以ox-LDL干预的M1、M2 型巨噬细胞为细胞模型，通过过表达或敲减（knock-down）PANDA而改变其表达水平，拟从正反两方面研究PANDA是否通过NF-YA调控巨噬细胞线粒体功能，引发细胞内糖酵解、OCR、OXPHOS、ATP产生等自身代谢以及线粒体DNA和膜电位的改变，进而引起巨噬细胞极化表型和胆固醇代谢的变化，以揭示巨噬细胞代谢重编程调控泡沫细胞形成和AS发生发展的分子机制。.研究结果显示：促炎亚型M1型巨噬细胞受到ox-LDL刺激PANDA表达水平增加，出现线粒体功能障碍，并上调胆固醇酯合成关键基因（ACAT-1）、下调胆固醇酯外流关键基因(ABCA1)的表达，促进泡沫细胞形成；敲减PANDA可能通过抑制核转录因子NF-YA调控线粒体能量代谢水平、线粒体DNA和膜电位，而起到保护巨噬细胞线粒体的功能，从而促进巨噬细胞向抑炎亚型M2型转化，进而通过巨噬细胞代谢重编程来影响其胆固醇酯合成和外流；过表达PANDA则与前相反，可能通过NF-YA调控线粒体的能量代谢，促进巨噬细胞向M1型转化，从而增加细胞内胆固醇酯的聚集，促进AS发展。.本课题从巨噬细胞代谢重编程的角度研究其调控极化表型和胆固醇代谢的具体机制，并从这一全新的角度对PANDA进行研究，阐明PANDA调控巨噬细胞线粒体功能、极化表型和胆固醇代谢的分子机制，针对这一新的靶标可以为研发新的抗AS 药物及治疗新策略的建立提供重要的理论依据，将开展一个崭新的、极具吸引力的研究领域，具有重要的经济和社会效益。