Role of ATII cell senescence in influenza pathogenesis in aging

ATII细胞衰老在流感发病机制中的作用

• 批准号: 10741215
• 负责人: IAN CHRISTOPHER DAVIS
• 金额: $ 44.83万
• 依托单位: OHIO STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10741215
• 关键词: Activities of Daily Living; Acute; Acute Respiratory Distress Syndrome; Age; Aging; Alveolar; Animals; Antiviral Agents; Attenuated; Biological Assay; Biology; Biophysics; C57BL/6 Mouse; Calorimetry; Cell Aging; Cell Energetics; Cell Separation; Cell physiology; Cells; Cellular Metabolic Process; Cessation of life; Chronic Obstructive Pulmonary Disease; Cytidine Diphosphate Choline; Development; Disease; Distal; Elderly; Energy Metabolism; Ensure; Equipment; Functional disorder; Gases; Genes; Glycolysis; Goals; Hypoxemia; Immune response; Inbred BALB C Mice; Infection; Inflammation; Influenza; Influenza A Virus, H1N1 Subtype; Influenza A virus; Influenza vaccination; Ion Transport; Lecithin; Lipids; Liquid substance; Lower respiratory tract structure; Lung; Lung diseases; Maintenance; Metabolic; Metabolic Clearance Rate; Metabolism; Methods; Mitochondria; Modeling; Mus; Non-Small-Cell Lung Carcinoma; Outcome; Oxidative Phosphorylation; PET/CT scan; Pathogenesis; Pathway interactions; Phospholipids; Physiological; Physiology; Population; Process; Production; Proteins; Public Health; Pulmonary Inflammation; Recycling; Reproducibility; Research Personnel; Resources; Respiratory Disease; Role; Severities; Site; Surface Tension; Testing; Viral Pathogenesis; Virus Diseases; Virus Replication; Western Blotting; X-Ray Computed Tomography; age effect; airway epithelium; alveolar type II cell; experimental study; extracellular; flexibility; glucose uptake; improved; in vivo; influenza epidemic; influenza infection; influenza virus vaccine; insight; mouse model; normal aging; novel; older patient; patient subsets; pulmonary function; seasonal influenza; senescence; success; surfactant; surfactant production; therapeutic target; vaccine access; vaccine efficacy

Alveolar type II (ATII) cells synthesize, secrete, and recycle surfactant proteins and lipids and regulate alveolar lining fluid depth by alveolar fluid clearance. Because both processes require large amounts of energy, ATII cells contain large numbers of mitochondria and mainly generate ATP by oxidative phosphorylation (OXPHOS). ATII cells are the primary site for influenza A virus (IAV) replication in the distal lung and central players in the pathogenesis of IAV-induced ARDS. Importantly, the elderly are over-represented in influenza-related fatalities. However, there is limited understanding of the impact of either aging or IAV infection on ATII cell function, senescence, and energy metabolism. ATII cells isolated from lungs of young (2-3 month-old) C57BL/6 mice primarily generate ATP by OXPHOS. In contrast, preliminary studies show ATII cells from aging (27 month-old) mice undergo a glycolytic shift and downregulate OXPHOS, possibly as a result of senescence. IAV infection of young mice causes a glycolytic shift and a decrease in OXPHOS which is reversed by CDP- choline treatment, resulting in a net increase in total ATP production, attenuated hypoxemia, and reduced pulmonary inflammation. IAV infection of aging mice causes more severe hypoxemia and further reduces OXPHOS without any compensatory increase in glycolysis, resulting in a net decrease in total ATP production despite the increased energy demands imposed by viral replication. Hence, it is hypothesized that influenza is more severe in the elderly because IAV infection imposes additional energetic demands for viral replication on ATII cells that lack inherent metabolic flexibility due to aging-associated senescence. By inhibiting de novo phospholipid synthesis, IAV also induces further mt dysfunction. Together, these effects provoke an energy crisis and render ATII cells unable to perform their normal physiologic functions (alveolar fluid clearance and surfactant synthesis), which results in progression to ARDS. It is further proposed that CDP- choline treatment improves OXPHOS in ATII cells and increases their functional capacity, thereby improving influenza outcomes. This hypothesis will be tested in two Specific Aims. Aim 1 will use a robust, reproducible, and relevant model of IAV-induced ARDS in 21-24 month-old C57BL/6 and BALB/c mice to define effects of aging, IAV infection, and CDP- choline treatment on ATII cell physiologic functions (surfactant production and alveolar fluid clearance), whole body metabolism (by open circuit calorimetry), lung glucose uptake (by PET/CT), lung inflammation, and viral replication. Aim 2 will use a comprehensive battery of flow cytometric assays and Western blot to quantify the level of senescence in ATII cells isolated from the lungs of mock- and IAV-infected young and aging mice and will analyze the impact of aging, IAV infection, and CDP-choline treatment on ATII cell energetics by extracellular flux analysis. Proposed experiments will provide novel mechanistic insights into the contribution of ATII cell dysfunction and senescence to development of more severe influenza in the elderly and will generate fundamental new information relevant to many pulmonary diseases of aging, such as COPD, IPF, and non-small cell lung cancer.

II 型肺泡 (ATII) 细胞合成、分泌和回收表面活性蛋白和脂质，并调节肺泡内壁液 深度由肺泡液间隙决定。由于这两个过程都需要大量能量，因此 ATII 细胞包含大量 线粒体，主要通过氧化磷酸化（OXPHOS）产生 ATP。 ATII 细胞是 甲型流感病毒 (IAV) 在远端肺中的复制和中枢在 IAV 诱导的 ARDS 发病机制中发挥作用。 重要的是，老年人在流感相关死亡中所占比例过高。但人们对此的了解还很有限 衰老或 IAV 感染对 ATII 细胞功能、衰老和能量代谢的影响。 ATII 细胞分离自 年轻（2-3 个月大）C57BL/6 小鼠的肺部主要通过 OXPHOS 产生 ATP。相反，初步研究表明 来自衰老（27 个月大）小鼠的 ATII 细胞经历糖酵解转变并下调 OXPHOS，可能是由于 衰老。年轻小鼠的 IAV 感染导致糖酵解转移和 OXPHOS 减少，而 CDP- 可以逆转这种情况 胆碱治疗，导致总 ATP 产生净增加，减轻低氧血症，并减少肺功能 炎。衰老小鼠的 IAV 感染会导致更严重的低氧血症，并进一步降低 OXPHOS，而没有任何作用 糖酵解的代偿性增加，导致尽管能量增加，但总 ATP 产量净减少 病毒复制所施加的要求。因此，推测流感在老年人中更为严重，因为 IAV 感染对缺乏固有代谢灵活性的 ATII 细胞的病毒复制提出了额外的能量需求 由于与衰老相关的衰老。通过抑制磷脂从头合成，IAV 还会进一步诱导 mt 功能障碍。 这些效应共同引发能源危机，并使 ATII 细胞无法执行其正常的生理功能 （肺泡液清除和表面活性剂合成），导致进展为 ARDS。进一步建议 CDP- 胆碱治疗可改善 ATII 细胞中的 OXPHOS 并增加其功能能力，从而改善流感 结果。该假设将在两个具体目标中得到检验。目标 1 将使用稳健、可重复且相关的模型 对 21-24 个月大的 C57BL/6 和 BALB/c 小鼠进行 IAV 诱导的 ARDS 分析，以确定衰老、IAV 感染和 CDP 的影响 胆碱治疗对全身 ATII 细胞生理功能（表面活性剂产生和肺泡液清除）的影响 代谢（通过开路量热法）、肺部葡萄糖摄取（通过 PET/CT）、肺部炎症和病毒复制。目的 2 将使用流式细胞术和蛋白质印迹的综合组合来量化 ATII 的衰老水平 从模拟感染和 IAV 感染的年轻和衰老小鼠的肺部分离出细胞，并将分析衰老、IAV 的影响 通过细胞外通量分析，感染和 CDP-胆碱治疗对 ATII 细胞能量学的影响。拟议的实验将 为 ATII 细胞功能障碍和衰老对更多细胞发育的贡献提供新的机制见解 老年人的严重流感，并将产生与许多肺部疾病相关的基本新信息 衰老，如慢性阻塞性肺病（COPD）、特发性肺纤维化（IPF）和非小细胞肺癌。