Endogenous metabolite restricts GM-CSF signaling pathway in pathogenic macrophages to ameliorate CNS Autoimmunity

摘要 确定一种治疗选择，可以调节先天免疫反应，而不通常抑制 免疫系统作为一个整体一直是改善MS患者治疗的关键障碍。 代谢谱，我们已经报道了omega-3的一种促分解脂代谢产物--解决素D1(RvD1) MS患者血浆中多不饱和脂肪酸含量显著降低，与此一致。 研究发现，多发性硬化症患者的omega-3代谢物水平较低，而omega-3代谢物是分解素的前体。 健康对照组，这一发现已经在这种疾病的动物模型中得到复制，实验性自身免疫 脑脊髓炎(EAE)。值得注意的是，我们发现每天补充Rvd1显著减弱了临床- 慢性和复发缓解型EAE的CAL症状。这些数据具有挑衅性，因为它们的翻译 潜在的，特别是因为免疫系统不会像类固醇和 大多数其他的多发性硬化症疗法。RvD1的免疫调节作用是通过其受体甲酰肽实现的 受体2(FPR2)，导致AMP激活的蛋白激酶(AMPK)的调节，AMPK是细胞的重要调节因子 新陈代谢。在其他人类疾病模型中，RvD1-FPR2信号级联通过诱导抗 巨噬细胞的炎症表型。然而，提供这种保护的机制仍然难以捉摸。 粒细胞-巨噬细胞集落刺激因子(GM-CSF)在这两种MS的病理过程中都起着关键作用 和EAE，促进炎症环境和神经元损伤。越来越多的人对抑制 GM-CSF信号作为MS治疗靶点的促炎作用在我们的初步工作中，我们 研究发现，RvD1处理抑制巨噬细胞的GM-CSF信号转导，这种抑制是AMPK去激活的。 悬垂的。然而，RvD1如何影响AMPK活性和GM-CSF信号以减弱EAE尚不清楚。我们的 长期目标是确定可用于治疗自身免疫性疾病的自然内源性信号机制。 MUNE疾病，特别是MS。我们在这里的总体目标是确定RvD1在MUNE中的作用机制。 解决MS小鼠模型中的炎症和残疾我们的中心假设是RvD1可以减轻 阻断GM-CSF信号导致促炎性巨噬细胞极化导致EAE疾病进展 将噬菌体转化为抗炎表型。巨噬细胞表型的潜在机制 开关是通过依赖于FPR2-AMPK的代谢重编程实现的。为了检验这一假设，我们的具体目标是 1)研究RvD1对中枢神经系统浸润性巨噬细胞表型和功能的影响。 以及2)确定RvD1对巨噬细胞代谢重编程的影响。 我们将结合免疫学、生化和创新的代谢组学AP来解决这些目标。 已经很好地控制住了问题。拟议的研究将为制定 在多发性硬化症期间消除炎症的创新治疗策略没有副作用，可能适用于 其他涉及免疫系统病原性激活的疾病。

ABSTRACT Identifying a therapeutic option that can modulate the innate immune response without generally suppressing the immune system as a whole has been a key barrier to improving treatment for patients with MS. Using metabolic profiling, we have reported that resolvin D1 (RvD1), a pro-resolving lipid metabolite of omega-3 polyunsaturated fatty acids, is significantly decreased in the plasma of patients with MS. Consistent with this finding, MS patients have lower levels of omega-3 metabolites, which are precursors of resolvins, compared to healthy controls, a finding that has been replicated in animal models of the disease, experimental autoimmune encephalomyelitis (EAE). Notably, we found that daily supplementation with RvD1 significantly attenuated clini- cal symptoms in both chronic and relapsing-remitting EAE. These data are provocative for their translational potential, particularly because the immune system is not depressed by RvD1 treatment as it is with steroids and most other MS therapies. The immunomodulatory effect of RvD1 is mediated through its receptor, formyl peptide receptor 2 (FPR2), leading to modulation of AMP-activated protein kinase (AMPK), an important regulator of cell metabolism. In other human disease models, the RvD1-FPR2 signaling cascade protects by inducing an anti- inflammatory phenotype in macrophages. However, the mechanism affording this protection remains elusive. Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a key player both in the pathology of both MS and EAE, promotes an inflammatory environment and neuronal damage. There is a growing interest in inhibiting the pro-inflammatory effects of GM-CSF signaling as a therapeutic target in MS. In our preliminary work, we found that RvD1 treatment inhibited GM-CSF signaling in macrophages and that this inhibition was AMPK de- pendent. However, how RvD1 affects AMPK activity and GM-CSF signaling to attenuate EAE is unclear. Our long-term goal is to identify natural endogenous signaling mechanisms that can be harnessed to treat autoim- mune diseases, particularly MS. Our overall objective here is to determine the mechanism of action of RvD1 in resolving inflammation and disability in mouse models of MS. Our central hypothesis is that RvD1 attenuates EAE disease progression by abrogating GM-CSF signaling resulting in the polarizing of pro-inflammatory mac- rophages into an anti-inflammatory phenotype. And the underlying mechanisms of macrophage phenotype switch are through FPR2-AMPK-dependent metabolic reprogramming. To test this hypothesis our specific aims are: 1) to identify the effects of RvD1 on the cellular phenotype and function of CNS-infiltrating macro- phages in EAE; and 2) to determine the effects of RvD1 on metabolic reprogramming in macrophages. We will address these aims with a combination of immunological, biochemical and innovative metabolomic ap- proaches that are already well in hand. The proposed studies will form the foundation for the development of innovative therapeutic strategies to resolve inflammation during MS with no side effects and will likely apply to other diseases involving pathogenic activation of the immune system.