The Role of Necroptosis in Aging

项目摘要/摘要 该研究的目的是确定坏死性下垂引起的炎症在衰老中的作用。慢性的， 低度炎症(发炎)是衰老的标志，是衰老的七大支柱之一。 炎症是老年人发病率和死亡率的一个非常重要的危险因素，因为 各种与年龄有关的疾病(如2型糖尿病、心血管疾病、癌症和神经退行性疾病 疾病)具有强烈的炎症性表型。尽管炎症、衰老和衰老之间存在联系- 关于相关疾病，目前我们对炎症在衰老中的作用的理解存在两个主要差距： (1)慢性低度炎症的分子机制(S)/途径(S)；(2)是否 炎症是衰老的原因之一，或继发于衰老。损伤相关的分子模式 (DAMPS)在年龄相关性慢性炎症中发挥作用，坏死性下垂是一种新发现的 在湿气的产生中起主要作用的程序性坏死。坏死性上睑下垂开始于 刺激依次激活受体相互作用蛋白激酶1(RIPK1)、RIPK3和混合谱系激酶 结构域样蛋白(MLKL)通过磷酸化。磷酸化MLKL与血浆结合并破坏血浆 细胞膜，释放湿气。湿气反过来通过以下途径触发慢性低度炎症 先天免疫细胞增加炎性细胞因子如肿瘤坏死因子的产生，从而激活RIPK1 在正反馈循环中的其他细胞中。研究表明，通过敲除RIPK3来抑制坏死性下垂可以减少 在几个小鼠模型中，坏死性下垂以及炎症。我们的初步数据提供了第一个证据 表明坏死性下垂可能在衰老中起作用，即野生型(WT)小鼠的坏死性下垂随着年龄的增长而增加 在加速衰老(SOD1-/-小鼠)模型中，减少/阻止坏死性下垂(遗传和 药理上)减少SOD1-/-小鼠的炎症。根据我们的初步数据，我们假设 坏死性下垂在慢性低度炎症中起作用，这种炎症随着年龄的增长而发生，并预防 坏死性下垂会减轻炎症，延长寿命，改善健康状况。为了测试 这一假设，在Aim1中，我们将通过以下方式确定坏死性下垂在年龄相关性慢性炎症中的作用 青年、中老年男性不同组织中坏死性下垂和炎症进展的鉴别 和雌性WT小鼠，并确定从遗传角度(RIPK3+/-和RIPK3-/-)减少坏死性下垂的效果 小鼠)或药理(Necrostatin-1s，一种RIPK1抑制剂)；在AIM2中，我们将确定 坏死性下垂通过评估细胞外基质的活性来调节年龄相关性炎症的机制 幼年和老年WT小鼠组织和细胞中的炎症途径及遗传效应的确定 坏死性下垂对炎症途径的抑制作用；在Aim3中，我们将确定坏死性下垂在衰老中的作用 通过比较RIPK3+/-和RIPK3-/-小鼠与WT小鼠的寿命、健康寿命和年龄相关病理。

Project Summary/Abstract The research objective is to characterize the role of necroptosis-induced inflammation on aging. Chronic, low-grade inflammation (inflammaging) is a hallmark of aging and is one of the ‘seven pillars of aging’. Inflammaging is a highly significant risk factor for both morbidity and mortality in the elderly people because a variety of age-related diseases (e.g. type 2 diabetes, cardiovascular diseases, cancer, and neurodegenerative diseases) share a strong inflammatory phenotype. Despite the link between inflammation, aging and age- associated diseases, two major gaps currently exist in our understanding of the role inflammation plays in aging: (1) the molecular mechanism(s)/pathway(s) responsible for the chronic, low-grade inflammation and (2) whether inflammaging is a causative factor in aging or occurs secondary to aging. Damage-associated molecular patterns (DAMPs) play a role in age-associated chronic inflammation and necroptosis is a newly identified pathway of programmed necrosis that plays a major in the generation of DAMPs. Necroptosis is initiated when necroptotic stimuli sequentially activate the receptor-interacting protein kinase 1 (RIPK1), RIPK3, and mixed lineage kinase domain like (MLKL) protein through phosphorylation. Phosphorylated MLKL binds to and disrupts the plasma membrane of cells, releasing DAMPs. The DAMPs in turn trigger chronic low-grade inflammation through increased production of inflammatory cytokines such as TNF by innate immune cells, which can activate RIPK1 in other cells in a positive feedback loop. Studies show that inhibiting necroptosis by knocking out Ripk3 reduces necroptosis as well as inflammation in several mouse models. Our preliminary data provides the first evidence showing that necroptosis might play a role in aging, i.e., necroptosis increases with age in wild type (WT) mice and in a model of accelerated aging (Sod1-/- mice), and reducing/blocking necroptosis (both genetically and pharmacologically) reduces inflammation in Sod1-/- mice. Based on our preliminary data, we hypothesize that necroptosis plays a role in chronic, low-grade inflammation, which occurs with age, and preventing necroptosis will attenuate inflammation, leading to increased lifespan and improved healthspan. To test this hypothesis, in Aim1 we will determine the role of necroptosis in age-associated chronic inflammation by identifying progression of necroptosis and inflammation in various tissues of young, middle-aged and old male and female WT mice and determine the effect of reducing necroptosis either genetically (Ripk3+/- and Ripk3-/- mice) or pharmacologically (necrostatin-1s, a RIPK1 inhibitor) on inflammation; in Aim2 we will determine the mechanism by which necroptosis mediates age-associated inflammation by assessing the activation of inflammatory pathways in tissues and cells of young and old WT mice and determine the effect of genetic inhibition of necroptosis on inflammatory pathways; in Aim3, we will determine the role of necroptosis in aging by comparing the lifespan, healthspan and age-associated pathology of Ripk3+/- and Ripk3-/- mice to WT mice.