Innate and Adaptive Immune Consequences of Necroptosis

建议书摘要 先天免疫系统对感染引起的组织动态平衡的破坏做出反应，但也 死亡的细胞和组织损伤。细胞通过不同的程序性细胞死亡方式死亡，包括凋亡和 坏死性下垂。细胞凋亡性死亡是由细胞平衡的健康组织生理学的正常组成部分 分裂并维持正常的组织大小和功能。由细胞凋亡引起的细胞死亡是耐受性的和非 炎症性，与坏死性下垂形成对比，后者是病理性和炎症性的。坏死性下垂涉及 受体相互作用的丝氨酸/苏氨酸蛋白激酶RIPK1、RIPK3和RIPK3复合体的形成 坏死下垂效应因子混合谱系激酶域样蛋白(MLKL)。直到最近，坏死性下垂还被认为 主要在控制感染方面发挥作用，主要作为一种故障安全策略来对抗病毒阻断 细胞凋亡。然而，在小鼠模型中的研究表明，细胞凋亡的成分缺乏 Caspase-8或FADD等机制导致由坏死性下垂引起的胚胎死亡，并依赖于 RIPK3和MLKL。在肠上皮中使用条件缺失caspase-8或FADD的其他研究 研究表明，阻断介导稳态细胞凋亡的通路会导致肠道炎症 与RIPK3水平升高和坏死性下垂有关。事实上，程序性细胞死亡的显著增加 据报道，炎症性肠病(IBD)患者的肠上皮细胞(IEC) 损伤与炎症加剧和肿瘤坏死因子(TNF)-a、And水平升高有关 细胞死亡的重要调节因子。利用一种新型的小鼠模型，我们可以诱导地触发IEC的坏死性下垂， 我们将确定IEC坏死性下垂如何影响肠道内环境平衡，我们将定义 炎症反应。我们之前的工作已经证实，肠道内的自稳细胞凋亡 上皮细胞是免疫抑制和耐受的主要驱动力，它印记了肠道单核巨噬细胞。 (MNP)具有“抑制炎症”和“诱导调节性的CD4T细胞”转录特征。这里 我们将定义坏死性下垂如何影响MNP的反应。我们将研究以下内容的组成和特点 小肠MNP群体对坏死性IEC的反应及其在不同先天性疾病中的作用 免疫功能与炎性介质的产生、固有淋巴样细胞的调节有关 功能以及CD4T辅助细胞分化。我们获得的知识将定义坏死性下垂 通过先天和适应性细胞群驱动炎症反应，作为 坏死性下垂在其他组织中的后果，并为开发新的治疗方法奠定了基础 用于慢性炎症性疾病，如IBD。

PROPOSAL SUMMARY The innate immune system responds to perturbations in tissue homeostasis resultant from infection but also dying cells and tissue damage. Cells die by different modes of programmed cell death including apoptosis and necroptosis. Cell death by apoptosis is a normal component of healthy tissue physiology that is balanced by cell division and maintains normal tissue size and function. Cell death by apoptosis is tolerogenic and non- inflammatory, and contrasts with necroptosis, which is pathological and inflammatory. Necroptosis involves the formation of a complex of receptor interacting serine/threonine protein kinases RIPK1, RIPK3 and the necroptosis effector mixed lineage kinase domain-like protein (MLKL). Up until recently, necroptosis was thought to function primarily in the control of infection and mainly as a fail-safe strategy that counters viral blockade of apoptosis. Studies in mouse models, however, have shown that deficiency in components of the apoptosis machinery such as caspase-8 or FADD leads to embryonic lethality driven by necroptosis and dependent on RIPK3 and MLKL. Other studies using conditional deletion of caspase-8 or FADD in the intestinal epithelium revealed that blocking the pathways that mediate homeostatic apoptosis precipitates intestinal inflammation associated with elevated levels of RIPK3 and necroptosis. Indeed, a notable increase in programmed cell death of intestinal epithelial cells (IEC) has been reported in patients with inflammatory bowel disease (IBD), and this damage is associated with heightened inflammation and increased levels of tumor necrosis factor (TNF)-a, an important mediator of cell death. Using a novel mouse model where we can inducibly trigger necroptosis of IEC, we will determine how IEC necroptosis impacts intestinal homeostasis and we will define the nature of the inflammatory response. Our previous work has established that homeostatic apoptosis within the intestinal epithelium is a major driver of immune suppression and tolerance, imprinting intestinal mononuclear phagocytes (MNP) with ‘suppression of inflammation’ and ‘induction of regulatory CD4 T cell’ transcriptional signatures. Here we will define how necroptosis impacts MNP responses. We will examine the composition and characteristics of the small intestinal MNP population that responds to necroptotic IEC and decipher its function in various innate immune functions relating to the production of inflammatory mediators, modulation of innate lymphoid cell function as well as the CD4 T helper cell differentiation. The knowledge we gain will define how necroptosis drives inflammatory responses by innate and adaptive populations of cells, serve as a roadmap for the consequences of necroptosis in other tissues, and lay the foundation for the development of novel therapeutics for chronic inflammatory diseases such as IBD.