Mechanism of Nlrp3 inflammasome activation by mitochondrial dysfunction

项目摘要 Nlrp 3炎性体与保护性和病理性免疫应答有关。其 适当的激活触发对入侵病原体包括流感病毒的先天免疫应答， 金黄色葡萄球菌和白色念珠菌及其过度反应是自身炎症反应的基础。 CAPS（cryopyrin associated periodic syndrome）Nlrp 3炎性小体也由以下物质触发： 导致常见的衰弱性疾病如痛风的发展的异常代谢状况， II型糖尿病和动脉粥样硬化。我们已经确定了一个新的步骤，通过该途径，Nlrp 3 炎性小体被激活，这揭示了先前未被识别的与外源性炎症因子激活的重叠。 凋亡途径我们实验室的初步研究表明，与这些凋亡途径相似，Nlrp 3 炎性小体激活诱导线粒体功能障碍，如正常阴性细胞的丧失所证明的。 线粒体内的潜力。在细胞凋亡过程中，线粒体膜电位的丧失与 随着线粒体脂质心磷脂从其在线粒体内部的位置移位， 膜外膜。这种运动伴随着心磷脂的氧化和释放， 细胞色素c的结合物进入膜间隙。外线粒体上的心磷脂 膜募集并结合caspase-8，从而驱动线粒体外膜的产生 细胞色素c从其与心磷脂的连接中释放出来，穿过细胞质并触发 免疫沉默细胞死亡的细胞凋亡。我们现在展示了绑定的要求和能力， 线粒体心磷脂由Nlrp 3共享，Nlrp 3先前显示在活化期间迁移到线粒体。 此外，线粒体膜电位的丧失，细胞凋亡中的一个决定性步骤，也是 Nlrp 3炎性体激活。在这个建议中，我们特别剖析了心磷脂在Nlrp 3激活中的作用。 并确定Nlrp 3炎性体激活反映细胞凋亡的程度。这些研究将决定 这两种途径的分歧点，不仅对促进我们对这一重要的 炎症通路，而且还因为一旦确定这种通路之间的转换可能被证明是靶点 进行治疗干预。操纵这些途径不仅对于修饰Nlrp 3应答是有吸引力的， 而且还具有从凋亡途径转换为炎症途径的潜力， 恶性肿瘤或隐性感染的情况。

Project Summary The Nlrp3 inflammasome has been linked to both protective and pathologic immune responses. Its appropriate activation triggers the innate immune response to invading pathogens including influenza virus, Staphylococcus aureus and Candida albicans and its excessive response underlies the autoinflammatory syndromes CAPS (cryopyrin associated periodic syndromes). The Nlrp3 inflammasome is also triggered by abnormal metabolic conditions that lead to the development of common debilitating disorders such as gout, type II diabetes mellitus and atherosclerosis. We have identified a novel step in the pathway by which the Nlrp3 inflammasome is activated that reveals a previously unrecognized overlap with the activation of extrinsic apoptotic pathways. Preliminary studies in our lab show that similar to these apoptotic pathways Nlrp3 inflammasome activation induces mitochondrial dysfunction as demonstrated by a loss of the normal negative potential within the mitochondria. During apoptosis this loss of mitochondrial membrane potential is associated with the translocation of the mitochondrial lipid cardiolipin from its location on the inner mitochondrial membrane to the outer membrane. This movement is accompanied by oxidation of cardiolipin and the release of its binding partner, cytochrome c, to the intermembrane space. Cardiolipin on the outer mitochondrial membrane recruits and binds caspase-8 that in turn drives the generation of an outer mitochondrial membrane pore through which cytochrome c, loose from its tether to cardiolipin, crosses to the cytosol and triggers immunologically silent cell death by apoptosis. We now show this requirement for and ability to bind mitochondrial cardiolipin is shared by Nlrp3, previously shown to migrate to the mitochondria during activation. Additionally, the loss of mitochondrial membrane potential, a defining step in apoptosis, is also required for Nlrp3 inflammasome activation. In this proposal we specifically dissect the role of cardiolipin in Nlrp3 activation and determine to what extent Nlrp3 inflammasome activation mirrors apoptosis. These studies will determine the point of divergence of these two pathways, important not only to advance our understanding of this vital inflammatory pathway but also because once identified this switch between pathways may prove to be a target for therapeutic intervention. Manipulation of these pathways is attractive not only for modifying Nlrp3 responses but also for the potential to switch from the apoptotic pathway to an inflammatory one as could be of benefit in the setting of malignancy or covert infections.