ITACONATE AS METABOLIC REGULATOR OF INFLAMMATION

摘要 代谢重排是免疫炎症激活的重要调节机制 细胞。2013年，奥尼尔团队的开创性工作表明，琥珀酸(TCA周期 代谢物)在巨噬细胞中充当关键的促炎信号，这项工作随后进行 通过深入研究琥珀酸在巨噬细胞和其他环境中的功能作用。然而， 控制琥珀酸积累和利用的调控机制仍不清楚。 在我们最近的工作中，使用系统生物学的方法，我们剖析了全球新陈代谢 巨噬细胞激活的结构，证实了O‘Neill的结果，并表明对内毒素 刺激时，TCA循环被失活的异柠檬酸脱氢酶(IDH1)打乱。 这种三氯乙酸循环断裂点使柠檬酸自由参与乙酰辅酶A的生产，并 重要的脂肪酸合成前体，在细胞内衣康酸的产生中， 二羧酸的代谢物，在结构上与琥珀酸非常相似。我们的初步数据显示 巨噬细胞激活过程中衣康酸的高产量在功能上是至关重要的，因为它 提供天然的代谢调节剂，平衡琥珀酸的促炎功能。 事实上，通过在体外用衣康酸预先处理巨噬细胞，我们观察到显著减少了 内毒素刺激后NO、IL-6、IL-1β的产生及其剂量依赖关系 抑制炎症小体激活过程中IL-1β和IL-18的产生。我们发现伊塔康星， 与琥珀酸的其他结构模拟物(如丙二酸)一样，丁二酸酯也是琥珀酸的抑制剂 脱氢酶(SDH)，电子转移链(ETC)中的一种酶，也称为复合体II。 在体外和体内都影响ROS的产生和TCA循环的活性。在这笔赠款中， 我们计划破译衣康酸的调节作用，并确定其对 体内的免疫反应。

ABSTRACT Metabolic rewiring is important regulatory mechanism of the inflammatory activation of immune cells. In 2013, seminal work by the O'Neill group demonstrated that succinate (TCA cycle metabolite) acts as a key proinflammatory signal in macrophages, and this work was followed by intense studies of succinate's functional roles in macrophages and other contexts. Yet, regulatory mechanisms that control succinate accumulation and utilization still remain unknown. In our recent work, using a systems biology approach, we dissected the global metabolic architecture of macrophage activation, corroborated O'Neill's result and showed that upon LPS stimulation, the TCA cycle becomes disrupted by inactivating isocitrate dehydrogenase (Idh1). This TCA cycle breakpoint frees citrate to participate in the production of acetyl-CoA, an important fatty acid synthesis precursor, and in the intracellular production of itaconic acid, a dicarboxilyc acid metabolite structurally very similar to succinate. Our preliminary data suggest that high production of itaconate during macrophage activation is functionally critical, as it provides a natural metabolic regulator to balance the pro-inflammatory function of succinate. Indeed, by pre-treating macrophages in vitro with itaconate, we observed significant reduction in the production of NO, IL-6, IL-1β in response to LPS stimulation, as well as dose-dependent inhibition of IL-1β and IL-18 production during inflammasome activation. We find that itaconate, like other structural mimetics of succinate (e.g. malonate) is serving as inhibitor of succinate dehydrogenase (Sdh), an enzyme also known as complex II in the electron transfer chain (ETC) affecting both ROS production and activity of TCA cycle both in vitro and in vivo. In this grant, we plan to decipher the regulatory role of itaconate and determine its functional impact on immune responses in vivo.