Mechanism of Nlrp3 inflammasome activation by mitochondrial dysfunction

项目摘要 Nlrp3炎症体与保护性和病理性免疫反应有关。它的 适当的激活会触发对包括流感病毒在内的入侵病原体的先天免疫反应， 金黄色葡萄球菌和白色念珠菌及其过度反应是自体炎症的基础 综合征CAPS(低温比林相关周期性综合征)。Nlrp3炎症小体也是由 代谢异常导致常见的衰弱疾病，如痛风， II型糖尿病和动脉粥样硬化。我们已经确定了Nlrp3途径中的一个新步骤 炎症小体被激活，显示出以前未被发现的与外源性蛋白激活的重叠 细胞凋亡途径。我们实验室的初步研究表明，与这些凋亡途径相似的是Nlrp3 炎性小体激活导致线粒体功能障碍，表现为正常阴性细胞的丢失 线粒体内的潜力。在细胞凋亡过程中，线粒体膜电位的这种丧失与 随着线粒体脂心磷脂从其在线粒体内部的位置移位 从膜到外膜。这种运动伴随着心磷脂的氧化和释放。 它的结合伙伴细胞色素c进入膜间隙。线粒体外表面的心磷脂 膜招募并结合caspase-8，caspase-8进而驱动线粒体外膜的产生 细胞色素c从系绳松散到心磷脂的孔，穿过这个孔进入胞浆并触发 免疫沉默的细胞因细胞凋亡而死亡。现在，我们展示了绑定的要求和能力 线粒体心磷脂由Nlrp3共享，先前显示在激活过程中迁移到线粒体。 此外，线粒体膜电位的丧失也是导致细胞凋亡的关键步骤。 NLRP3炎症体激活。在这项提案中，我们特别剖析了心磷脂在Nlrp3激活中的作用 并确定Nlrp3炎症体激活在多大程度上反映了细胞凋亡。这些研究将确定 这两条道路的分歧点，不仅对推进我们对这一至关重要的认识至关重要 炎症途径，也是因为一旦确定了这种途径之间的切换可能被证明是一个目标 进行治疗干预。操纵这些通路不仅对修饰Nlrp3反应有吸引力 但也有可能从凋亡途径切换到炎症途径，这可能对 恶性或隐蔽感染的背景。

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.