Crosstalk between CES1 and PPAR gamma and LXR alpha in macrophages

摘要 生物活性脂质和炎症的交叉是组织损伤期间免疫细胞的中心特征， 特别是在巨噬细胞中。当稳态机制不能解决炎症反应和/或 变得适应不良，慢性低度炎症状况或过度伤口愈合事件可 确立了习例如，肺纤维化和动脉粥样硬化部分是由于过度活跃的组织修复和 有缺陷的炎症消退。在这一问题的性质方面存在着重大的知识空白， 脂质相互作用组在健康和疾病中的作用，以及它如何调节炎症， 或促进解决/修复。因此，“炎症解决方案的缺陷”是一个主要的主题， 通过这个提案。这项资助的具体目标是从机制上了解免疫调节 我们已经观察到代谢丝氨酸水解酶之间的串扰-称为人类羧酸酯酶1 （CES1）-和脂质敏感核受体PPARgamma和LXR alpha，其可影响巨噬细胞表型 并在暴露于“细胞因子相关分子”（如细胞因子和氧化低密度脂蛋白）后发挥作用。 脂蛋白（oxLDL）。为了解决这个问题，我们假设CES1在巨噬细胞中的一个功能是 调节内源性配体的水平，所述内源性配体在消退的情况下被PPARgamma和LXR alpha感知。 炎症，从而调节这些推定的抗炎受体的活性。这将被测试， 两个目标将：（i）表征CES 1和脂质敏感受体PPARgamma之间的串扰， （ii）评估小鼠Ces1d（人CES1的小鼠直系同源物）在肺中表达LXR α的机制 调节肺纤维化模型中"交替极化"巨噬细胞的活性。人单核细胞- 衍生的巨噬细胞与关键基因敲除和创新的小鼠模型将用于研究 巨噬细胞激活刺激对生物化学、基因组学和脂质组学输出的影响。这样做的影响 该项目将展示CES1如何转导细胞外信号，形成免疫表型 巨噬细胞在这个阶段，CES1与核受体PPARgamma和LXR alpha之间的联系是 然而，获得这一知识将允许新的和创新的方法来治疗性地调节 分别加剧动脉粥样硬化和肺纤维化的M1和M2巨噬细胞的活性。以下 该项目的成功完成，我们将更好地了解CES1调节的机制， 细胞水平的氧化化学品（氧化脂质和氧化固醇），形成的背景下，脂质和 化学性炎症此外，我们将更好地了解这些事件的后续相互作用。 具有蛋白质的化合物（例如，配体激活的转录因子），最终形成 它们对健康和损伤中免疫极化刺激的细胞反应。

Abstract The intersection of bioactive lipids and inflammation is a central feature of immune cells during tissue injury, particularly in macrophages. When homeostatic mechanisms fail to resolve inflammatory responses and/or become maladaptive, chronic low-grade inflammatory conditions or excessive wound healing events can be established. For example, lung fibrosis and atherosclerosis, in part, results from overactive tissue repair and defective inflammation resolution, respectively. There are major knowledge gaps regarding the nature of the lipid interactome in health and disease, and how it modulates inflammation to either exacerbate tissue damage or promote resolution/repair. Thus, ‘defects in inflammation resolution programs’ is a major theme that runs through this proposal. The specific goal of this grant is to mechanistically understand the immunoregulatory crosstalk we have observed between a metabolic serine hydrolase – termed human carboxylesterase 1 (CES1) – and the lipid-sensing nuclear receptors PPARgamma and LXRalpha, which can affect macrophage phenotype and function after exposure to ‘danger-associated molecules’, such as cytokines and oxidized low-density lipoproteins (oxLDL). To attack this problem, we hypothesize that one function of CES1 in macrophages is to regulate the levels of endogenous ligands that are sensed by PPARgamma and LXRalpha in the setting of resolving inflammation, thus modulating the activity of these putative anti-inflammatory receptors. This will be tested with two aims that will: (i) Characterize the cross talk between CES1 and the lipid-sensing receptors PPARgamma and LXRalpha; (ii) Evaluate the mechanisms by which murine Ces1d (the mouse ortholog of human CES1) in lung regulates the activity of ‘alternatively polarized’ macrophages in a pulmonary fibrosis model. Human monocyte- derived macrophages with key genes knocked out and an innovative mouse model will be used to study the effects of macrophage-activating stimuli on biochemical, genomic, and lipidomic outputs. The impact of this project is that it will demonstrate how CES1 transduces extracellular signals that shape the immunophenotype of macrophages. At this stage, the links between CES1 and the nuclear receptors PPARgamma and LXRalpha are unclear; however, obtaining this knowledge would allow new and innovative ways to therapeutically temper the activities of M1 and M2 macrophages that exacerbate atherosclerosis and lung fibrosis, respectively. Following the successful completion of this project, we will better understand the mechanisms by which CES1 regulates cellular levels of oxidized chemicals (oxylipins and oxysterols) that are formed in the context of lipid- and chemical-driven inflammation. Further, we will have a better view of the subsequent interactions of these compounds with proteins (e.g., ligand-activated transcription factors) in macrophages that ultimately shape their cellular response to immune-polarizing stimuli in health and injury.