Regulation of cytosolic pattern recognition receptor signaling in macrophages

描述（由申请人提供）：入侵的病原体被先天免疫系统的模式识别受体（PRRs）识别为第一道防线。巨噬细胞中核苷酸结合和富含亮氨酸重复序列（NLR）蛋白家族和黑色素瘤2 （AIM2）中缺失的PRRs的激活导致炎症小体的形成。炎性小体是炎性半胱天冬酶激活以及随后促炎细胞因子白介素-1的成熟和释放所必需的蛋白质平台。和地震。炎症小体的组装依赖于PYRIN结构域（PYD）介导的接合蛋白ASC对活化的PRRs的募集，然后募集前caspase -1。此外，Caspase-4、-5和-8也参与其中。然而，胞质内PRRs激活炎性小体的分子机制，特别是这一过程的调控和终止机制尚不清楚。我们发现了一个仅由PYD组成的小蛋白家族，称为含PYD （PYDC或POP）蛋白。我们发现PYDCs通过阻断炎性小体形成所必需的PYD-PYD相互作用来抑制炎性小体的激活。然而，它们在体内宿主防御和炎症疾病中的确切作用和贡献仍然未知。炎性小体对宿主防御至关重要；然而，不适当的炎症小体激活也会导致过度和慢性炎症，组织破坏和日益严重的自身炎症性疾病的衰弱症状。因此，在急性感染期间，平衡的炎性小体反应允许病原体清除，同时通过及时终止来防止全身性炎症，对体内平衡至关重要。我们假设PYDC蛋白的作用是通过负反馈机制维持这种平衡的炎性小体反应。由于小鼠缺乏PYDC蛋白，我们建立了新的小鼠模型来模拟人类进化的更复杂的炎性体调节。我们建议在所有已知的炎症小体激活情况下确定pydc介导的炎症小体调节和终止：病原体感染/病原体相关分子模式（PAMP），组织损伤/损伤相关分子模式（DAMP）和巨噬细胞和体内的遗传性PRR突变。我们将重点关注炎性小体激活PRRs。在目标1中，我们将确定巨噬细胞中每个PYDC的炎性小体调节和终止的分子机制，在目标2中，我们建议确定PYDC介导的炎性小体体内调节。总的来说，我们的研究旨在建立PYDC家族在感染和炎症性疾病中的特异性炎症小体调节功能，我们期望这将显著促进我们对先天免疫、宿主防御和炎症性疾病的基本生物学原理以及这些反应被调节的机制的理解。

DESCRIPTION (provided by applicant): Invading pathogens are recognized by pattern recognition receptors (PRRs) of the innate immune system as a first line of defense. Activation of PRRs from the Nucleotide-binding and leucine-rich repeat containing (NLR) protein family and Absent in melanoma 2 (AIM2) in macrophages results in inflammasome formation. Inflammasomes are protein platforms that are essential for the activation of inflammatory Caspases and subsequently for the maturation and release of the pro-inflammatory cytokines interleukin (IL)-1? and IL-18. Assembly of inflammasomes depends on PYRIN domain (PYD)-mediated recruitment of the adaptor protein ASC to activated PRRs, which then recruits pro-Caspase-1. In addition, Caspase-4, -5 and -8 participate. However, the molecular mechanism of inflammasome activation by cytosolic PRRs and in particular, regulation and termination of this process is poorly understood. We discovered a family of small proteins composed of only a PYD, called PYD-containing (PYDC or POP) proteins. We show that PYDCs function to inhibit inflammasome activation by blocking the PYD-PYD interactions essential for inflammasome formation. However, their precise role and contribution to in vivo host defense and inflammatory disease is still unknown. Inflammasomes are essential for host defense; however, inappropriate inflammasome activation also causes excessive and chronic inflammation, tissue destruction and the debilitating symptoms of the growing autoinflammatory diseases. Therefore, a balanced inflammasome response to allow pathogen clearance during acute infection, while preventing systemic inflammation through timely termination, is essential for homeostasis. We hypothesize that it is the role of the PYDC proteins to maintain this balanced inflammasome response through a negative feedback mechanism. Since PYDC proteins are lacking from mice, we generated novel mouse models to simulate the more complex inflammasome regulation evolved in humans. We propose to determine PYDC-mediated inflammasome regulation and termination during all known scenarios of inflammasome activation: pathogen infection/pathogen-associated molecular pattern (PAMP), tissue damage/damage associated molecular pattern (DAMP) and hereditary PRR mutation in macrophages and in vivo. We will focus on select inflammasome-activating PRRs. In aim 1 we will determine the molecular mechanism of inflammasome regulation and termination for each PYDC ex vivo in macrophages and in aim 2 we propose to determine PYDC-mediated inflammasome regulation in vivo. Collectively, our study is designed to establish the specific inflammasome regulatory function of the PYDC family during infection and inflammatory disease, which we expect will significantly advance our understanding of fundamental biological principles underlying innate immunity, host defense and inflammatory disease and the mechanism by which these responses are regulated.