TLR4-MEDIATED EPIGENETIC AND SENESCENCE MECHANISMS IN EMPHYSEMA

项目总结 慢性阻塞性肺病现在是全球第三大死亡原因。肺气肿，以空域扩大为特征 和气体交换障碍，是COPD的一个主要亚型。香烟烟雾暴露的累积效应 (CS)和整个生命周期内的环境毒素是导致癌症发生的重要因素 肺气肿。然而，人们对限制治疗的潜在机制知之甚少。我们的整体 目标是了解我们的肺如何维持正常结构完整性和 他们如何防止吸入毒素，如CS。我们确定了先天免疫受体的关键作用， Toll样受体4(TLR4)在肺维持和防止衰老和损伤的不当激活中的作用 小路。不幸的是，年龄和CS是COPD的两个最常见的危险因素，导致 TLR4水平，因此易患肺气肿。我们的研究将填补我们目前在理解如何 免疫系统，在特定的肺细胞中，可以影响肺保护反应，即使在缺乏 感染，从而提供潜在的新的治疗靶点。TLR4缺乏症与CS的临床应用 肺气肿的相关实验模型，我们确定了衰老分子的机制作用， P16INK4a和DNA修饰酶HDAC2、DNMT3A和TET2在肺气肿中表达。此外，我们还提供 首次有体内证据表明p16INK4A增加与肺气肿有关。我们的总体假设是 结构细胞TLR4是维持正常肺完整性所必需的，在基线和CS后，通过抑制 P16INK4a通过HDAC2-DNMT3A-TET2介导的机制。我们将使用年龄和CS的组合- 暴露在人类和小鼠肺/细胞中，以及创新的基因操作，以在 目的如下：1)确定TLR4表达随年龄增长和CS减少的机制以及 特定结构细胞中TLR4在肺气肿发病中的作用2)确定降低的机理 TLR4基因缺陷和CS暴露的细胞中的HDAC2。3)识别HDAC2和DNMT3A/TET2介导的机制 P16INK4A的诱导以及特定结构细胞中p16INK4A对肺气肿的作用。我们的研究将 扩大我们对肺气肿分子驱动因素的基本理解，建立以前未被认识到的 先天免疫、衰老和DNA修饰之间的相互作用并提示未来的预防或 一系列与年龄和CS相关的肺部疾病的治疗方法。

PROJECT SUMMARY COPD is now the 3rd leading cause of death worldwide. Emphysema, characterized by airspace enlargement and impaired gas exchange, is a major subtype of COPD. The cumulative effects of cigarette smoke exposure (CS) and environmental toxins across the lifespan are important contributing factors to the development of emphysema. Yet very little is known about the underlying mechanisms, which limits therapies. Our overall goals are to understand the molecular mechanisms of how our lungs maintain normal structural integrity and how they protect against inhaled toxins, such as CS. We identified a critical role for an innate immune receptor, Toll-like receptor 4 (TLR4), in lung maintenance and in preventing inappropriate activation of aging and injury pathways. Unfortunately, age and CS, two of the most common risk factors for COPD, result in inadequate levels of TLR4, thus predisposing to emphysema. Our studies will fill current gaps in our understanding of how the immune system, in specific lung cells, can impact lung-protective responses even in the absence of infection, thereby offering potential new therapeutic targets. Using TLR4-deficiency and CS as clinically relevant experimental models of emphysema, we identified mechanistic roles for the senescence molecule, p16INK4A, and DNA-modifying enzymes, HDAC2, Dnmt3a and Tet2, in emphysema. In addition, we offer the first in vivo evidence that increased p16INK4A contributes to emphysema. Our overall hypothesis is that structural cell TLR4 is required to maintain normal lung integrity, at baseline and after CS, by inhibiting p16INK4A via HDAC2-Dnmt3a-Tet2-mediated mechanisms. We will use a combination of age- and CS- exposed human and mouse lungs/cells as well as innovative gene manipulations to test this hypothesis in the following Aims: 1) Identify mechanisms of decreased TLR4 expression with aging and CS and the contribution of TLR4 in specific structural cells to emphysema. 2) Determine the mechanisms of decreased HDAC2 in TLR4-deficient and CS-exposed cells. 3) Identify HDAC2 and Dnmt3a / Tet2 -mediated mechanisms of p16INK4A induction and the contribution of p16INK4A in specific structural cells to emphysema. Our studies will expand our basic understanding of the molecular drivers of emphysema, establish previously unrecognized interactions amongst innate immunity, senescence and DNA modifications and inform future preventative or therapeutic approaches to a range of age- and CS-related lung diseases.