Does Necroptosis Play a Role in Inflammation and Aging

慢性低度炎症(炎症)是衰老的标志，也是两者的主要危险因素。 老年人的发病率和死亡率。此外，炎症是多种疾病的主要危险因素。 与年龄有关的疾病，如2型糖尿病、心血管疾病、癌症、神经退行性疾病、 虚弱等。尽管炎症、衰老和年龄相关疾病之间存在联系，但我们不知道 老年动物慢性低度炎症的分子机制(S)/途径(S) 以及慢性炎症的增加是否是衰老和与年龄相关的疾病的致病因素。 坏死性下垂是一种新近发现的程序性坏死途径，它通过裂解导致细胞死亡。 导致死亡细胞释放损伤相关的分子模式(DAMP)。 湿气是炎症的有效诱因，循环中的湿气已被证明随着年龄的增长而增加。 并与个体的炎症水平密切相关。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 坏死性下垂可以减轻炎症，延长寿命，改善健康状况， 减少与年龄相关的病理改变。我们将使用转基因小鼠模型和一种药物 通过靶向受体相互作用蛋白激酶(RIPK)1或2和 混合谱系激酶域(MLKL)蛋白，参与了坏死性下垂的发生。 目的：1.确定坏死性下垂在随年龄增长的慢性炎症中的作用以及 正在经历坏死性下垂的细胞。我们将确定减少坏死性下垂的遗传效果(使用 RIPK3/-、RIPK3-/-、MLKL/-和MLKL-/-小鼠)或药理(使用RIPK1抑制剂Necrostatin-1s治疗) 关于炎症的。我们还将确定在老年小鼠的选定组织中经历坏死性下垂的细胞类型(S)。 根据我们的假设，我们预测，随着年龄的增长，那些在坏死性下垂中表现出上调的组织将 显示促炎症细胞因子的产生增加，减少/阻止坏死性下垂将减少 这些组织中的炎症以及促炎细胞因子的循环水平。 AIM2.找出随年龄增加坏死性下垂的途径并确定其机制(S) 调节因坏死性下垂引起的与年龄相关的炎症增加。肿瘤坏死因子α、氧化应激和 MTOR信号被认为可以启动坏死性下垂，并且这些信号通路随着年龄的增长而增加。在目标2中， 我们用特定的方法确定了这些通路在与年龄相关的坏死性下垂增加中所起的作用。 每条通路的抑制剂。坏死细胞释放的湿气通过以下途径诱导炎症 3个通路的激活：IKK-NF-κB、MAPK-AP1和炎症体通路。在《目标2》中，我们还将 评估AGE对WT小鼠不同组织中这些通路激活的影响，并确定 当RIPK3和MLKL基因敲除小鼠的坏死性下垂减少/阻断时，以下哪条途径减少 通过Necrostatin-1s治疗。 Aim3.确定坏死性下垂在衰老中的作用。在目标3中，有两组小鼠患有坏死性下垂 被阻断/减少的将被比作野生型小鼠。小鼠模型(例如，RIPK3和/或MLKL基因敲除 小鼠)将被用于我们在目标1中发现的阻滞性炎症。寿命，健康期限(例如，活动，旋转棒 表现、握力、胰岛素敏感性、认知等)，以及这些小鼠的年龄相关病理 可以与WT小鼠进行比较。根据我们的假设，我们预测减少/阻断坏死性下垂将延缓 衰老表现为健康寿命延长，病理改变减少，寿命延长。这些数据将 提供第一个直接证据，证明坏死性下垂引起的炎症与衰老直接相关，而且 慢性低度炎症在衰老和病理增加以及与年龄相关的疾病中起着一定的作用。

Chronic, low-grade inflammation (inflammaging) is a hallmark of aging and is a major risk factor for both morbidity and mortality in the elderly humans. In addition, inflammation is a major risk factor for a variety of age-related diseases, e.g. type 2 diabetes, cardiovascular disease, cancer, neurodegenerative diseases, frailty, etc. Despite the link between inflammation, aging, and age-associated diseases, we do not know the molecular mechanism(s)/pathway(s) responsible for the chronic, low-grade inflammation seen in old animals and whether the increase in chronic inflammation is a causative factor in aging and age-related diseases. Necroptosis is a recently identified pathway of programmed necrosis that induces cell death through the lysis of cells, resulting in the release of damage-associated molecular patterns (DAMPs) from the dead cells. DAMPs are potent inducers of inflammation, and circulating DAMPs have been shown to increase with age in humans and to be strongly correlated to the level of inflammation in the individual. 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, improved healthspan, and reduced age-related pathology. We will use genetically modified mouse models and a pharmacological intervention to block/reduce apoptosis by targeting the receptor-interacting protein kinases (RIPK) 1 or 2 and mixed lineage kinase domain like (MLKL) protein, which are involved in the initiation of necroptosis. Aim1. Determine the role of necroptosis in chronic inflammation that occurs with age and the types of cells undergoing necroptosis. We will determine the effect of reducing necroptosis either genetically (using Ripk3+/-, Ripk3-/-, Mlkl+/-, and Mlkl-/- mice) or pharmacologically (treating with necrostatin-1s, a RIPK1 inhibitor) on inflammation. We will also identify the cell type(s) that undergo necroptosis in selected tissues of old mice. Based on our hypothesis, we predict that those tissues showing an up-regulation in necroptosis with age will show an increase in production of proinflammatory cytokines and reducing/blocking necroptosis will decrease inflammation in these tissues as well as circulating levels of proinflammatory cytokines. Aim2. Identify the pathways that increase necroptosis with age and determine the mechanism(s) that mediates the age-related increase in inflammation arising from necroptosis. TNFα, oxidative stress, and mTOR signaling have been proposed to initiate necroptosis, and these pathways increase with age. In Aim 2, we determine the role of these pathways play in the age-related increase in necroptosis using specific inhibitors to each of the pathways. DAMPs released by necroptotic cells induce inflammation through activation of three pathways: the IKK-NF-κB, MAPK-AP1 and inflammasome pathways. In Aim 2, we will also assess the effect of age on the activation of these pathways in various tissues of WT mice and determine which of the pathways are reduced when necroptosis is reduced/blocked in Ripk3 and Mlkl knockout mice or by necrostatin-1s treatment. Aim3. Determine the role of necroptosis in aging. In Aim 3, two groups of mice in which necroptosis has been blocked/reduced will be compared to wildtype mice. Mouse models (e.g., Ripk3 and/or Mlkl knockout mice) will be used that we find block inflammaging in Aim 1. The lifespan, healthspan (e.g., activity, rotarod performance, grip strength, insulin sensitivity, cognition, etc.), and age-associated pathology of these mice will be compared to WT mice. Based on our hypothesis, we predict that reducing/blocking necroptosis will retard aging as shown by improved healthspan, reduced pathology, and increased lifespan. These data would provide the first direct evidence that necroptosis induced inflammation is directly involved in aging and that chronic, low-grade inflammation plays a role in aging and the increase in pathology and age-related diseases.