Role of choline metabolism in activated macrophage phenotypes

PRO项目总结 巨噬细胞（MO）在许多疾病的炎症传播中起着至关重要的作用。最近的工作已经 突出了风湿性疾病滑膜组织中MO功能的异质性。激活MO的存在 滑膜中促炎和抗炎MO群体的不平衡与 疾病进展和临床表现。在其他刺激中，关节中的MO被损伤激活 相关分子模式（DAMP），其被NLRP 3炎性体感知并激活IL-1 β和IL-18-β。 使关节细胞从静止调节状态转变为高度代谢活性状态的依赖性炎症。 胆碱代谢异常正在成为细胞活化和炎症的代谢标志。胆碱 是一种类似维生素的必需营养素，由胆碱激酶α（ChoK）磷酸化，作为新的 合成磷脂酰胆碱（PC）。新兴的脂质组学研究表明，一些风湿性疾病表现出 胆碱循环水平的增加和滑液中磷脂（PL）谱的改变。此外，本发明还提供了一种方法， 滑膜MO表达胆碱转运蛋白，提示胆碱代谢在滑膜MO活化中作用。 PI先前的工作已经确定了维生素样营养素胆碱摄取的重要作用， IL-1 β和IL-18向PC合成和NLRP 3炎性小体依赖性产生的动员 激活MO ChoK对胆碱摄取或磷酸化的抑制改变了线粒体PL含量， 减少细胞ATP，导致线粒体自噬的启动，防止线粒体DNA氧化， 最终阻止NLRP 3炎性体的激活以及IL-1 β和IL-18的产生。此外，本发明还提供了一种方法， ChoK抑制降低痛风和Muckle威尔斯综合征小鼠模型中的炎症。 PI现在提供了初步数据，表明MO中的胆碱利用调节MO生物学，包括 MO极化。她还描述了LPS诱导的MO激活伴随着代谢和PL， 重组的变化取决于胆碱的可用性。此外，她还展示了关于 ChoK在骨关节炎中的作用。这些发现提出了一个有吸引力的假设，即营养代谢可以 在风湿性疾病的情况下调节滑膜激活的MO表型。 目前的建议将提供一个全面的视野胆碱代谢和PL组成的作用 在MO激活和生物学，通过三个具体的目标。目的1将评估胆碱代谢在MO 分化和极化;目标2将探讨胆碱可用性对其相关代谢的作用 和生物能量的变化;目标3将研究胆碱的可用性及其在OA滑膜中的磷酸化。 拟定的研究和培训计划将帮助PI过渡为独立研究者，并将提供 她在免疫代谢、转化研究、代谢组学和线粒体生物能量学方面具有专长。 这项工作将在骨髓生物学专家Michael Karin博士和Monica博士的指导下进行 古马，关节炎研究专家，以及恒星咨询委员会的指导。

PRO PROJECT SUMMARY Macrophages (MO) play a crucial role in the propagation of inflammation in many diseases. Recent work has highlighted functional MO heterogeneity in synovial tissue of rheumatic diseases. The presence of activated MO and the imbalance of pro-inflammatory and anti-inflammatory MO populations in the synovium has been related to disease progression and clinical manifestations. Among other stimuli, MO in the joints are activated by damage associated molecular patterns (DAMP), that are sensed by NLRP3 inflammasome and activate IL-1 and IL-18- dependent inflammation that shifts joint cells from a resting regulatory state to a highly metabolically active one. Abnormal choline metabolism is emerging as a metabolic hallmark of cell activation and inflammation. Choline is a vitamin-like essential nutrient that is phosphorylated by choline kinase alpha (ChoK) as precursor to newly synthesized phosphatidylcholine (PC). Emerging lipidomic studies indicate that some rheumatic diseases exhibit an increase of choline circulating levels and an altered phospholipid (PL) profile in the synovial fluid. In addition, synovial MO express choline transporters, suggesting a role of choline metabolism in synovial MO activation. Previous work by the PI has established an essential role for the vitamin-like nutrient choline uptake and mobilization towards PC synthesis and NLRP3 inflammasome-dependent production of IL-1 and IL-18 in activated MO. Inhibition of choline uptake or phosphorylation by ChoK altered mitochondrial PL content and reduced cellular ATP, which resulted in the initiation of mitophagy, prevention of mitochondrial DNA oxidation, and ultimately, prevention of activation of NLRP3 inflammasome and production of IL-1 and IL-18. In addition, ChoK inhibition decreased inflammation in murine models of gout and Muckle Wells syndrome. The PI now provides preliminary data suggesting that choline utilization in MO modulates MO biology including MO polarization. She also describes that LPS-induced MO activation is accompanied by metabolic and PL reorganization changes that are dependent on choline availability. Additionally, she shows novel data about the role of ChoK in osteoarthritis. These findings suggest the attractive hypothesis that nutrient metabolism could modulate synovial activated MO phenotypes in the context of rheumatic diseases. The current proposal will provide a comprehensive vision of the role of choline metabolism and PL composition in MO activation and biology, through three Specific Aims. Aim 1 will evaluate choline metabolism in MO differentiation and polarization; Aim 2 will explore the role of choline availability on their associated metabolic and bioenergetic changes; Aim 3 will investigate choline availability and its phosphorylation in the OA synovium. The proposed studies and training plan will help PI’s transition to an independent investigator and will provide her with expertise in immunometabolism, translational research, metabolomics, and mitochondrial bioenergetics. The work will be performed with the mentorship of Dr. Michael Karin, an expert in myeloid biology, and Dr. Monica Guma, an expert in arthritis research, as well as guidance from a stellar Advisory Committee.