ITACONATE AS METABOLIC REGULATOR OF INFLAMMATION

摘要 代谢重连是免疫系统炎症激活的重要调节机制， 细胞2013年，奥尼尔小组的开创性工作表明，琥珀酸（TCA循环） 代谢物）在巨噬细胞中充当关键的促炎信号，并且这项工作随后进行 通过对琥珀酸在巨噬细胞和其他环境中的功能作用的深入研究。然而， 控制琥珀酸积累和利用的调节机制仍然未知。 在我们最近的工作中，使用系统生物学方法，我们解剖了全球代谢 巨噬细胞活化的结构，证实了奥尼尔的结果，并表明在LPS 刺激后，TCA循环因失活异柠檬酸脱氢酶（Idh 1）而中断。 该TCA循环断点释放柠檬酸盐以参与乙酰辅酶A的产生， 重要的脂肪酸合成前体，并在细胞内生产的衣康酸， 二羧酸代谢物结构上与琥珀酸非常相似。我们的初步数据显示 在巨噬细胞活化过程中衣康酸的高产量在功能上是关键的，因为它 提供天然代谢调节剂以平衡琥珀酸的促炎功能。 事实上，通过在体外用衣康酸盐预处理巨噬细胞，我们观察到巨噬细胞中的 NO、IL-6、IL-1β的产生与LPS刺激有关，并呈剂量依赖性 抑制炎性小体活化过程中IL-1β和IL-18的产生。我们发现衣康酸盐， 与琥珀酸酯的其它结构模拟物（例如丙二酸酯）一样， 脱氢酶（Sdh），一种在电子转移链（ETC）中也称为复合物II的酶 在体外和体内均影响ROS产生和TCA循环活性。在这份补助金中， 我们计划破译衣康酸盐的调节作用，并确定其功能性影响， 体内免疫反应。

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.