Age-dependent differences in the immune response to human metapneumovirus

摘要 人偏肺病毒（HMPV）是幼儿下呼吸道感染的主要原因， 免疫功能低下的人和老年人，导致高发病率和死亡率。很少有研究 研究了为什么HMPV在老年人中更严重。该提案旨在填补这一知识空白， HMPV发病机制。我的初步数据发现，感染HMPV的老年小鼠表现出延迟的病毒性， 清除，增加肺部炎症，增加共表达HMPV-四聚体的CD 8 + HMPV-四聚体+细胞 抑制性标志物PD-1、TIM-3和LAG-3。我假设老年人严重的HMPV感染是 由CD 8 + T细胞反应受损引起。在目标1中，我将调查 使用10 X Multiomics研究在感染HMPV的老年宿主中观察到的小鼠CD 8 + T细胞损伤 肺直接离体和同基因移植。10 X Multiomics将阐明与年龄相关的表观遗传变化 在CD 8 + T细胞中，而同基因移植将年轻的CD 8 + T细胞转移到老年宿主中，反之亦然， 确定CD 8 + T细胞是否是导致对HMPV的免疫应答受损的主要免疫细胞（即， 体重减轻增加、临床严重程度、病毒清除延迟）。在目标2中，我将调查 CD 8 + T细胞损伤，即肺泡巨噬细胞（AM）造成的损伤。我会用21色多光谱流 使用流式细胞术板计数老年宿主中的M1和M2巨噬细胞群体。体外共培养和 AM和CD 8 + T细胞的transwell测定将确定AM是否直接损害CD 8 + T细胞。选择性消耗 老年小鼠中AM的数量和年轻巨噬细胞的过继转移将决定AM如何促进 老年宿主的免疫反应受损还将进行10 X Multiomics，以研究 AM中与年龄相关的表观遗传变化可能导致其异常的M2积累，我已经 这也是我的初步数据。 该建议旨在了解老年宿主对HMPV反应的机制差异， 这将有助于阐明为什么老年人中HMPV感染更严重。这些研究有可能 转化为临床环境，并有助于更好地管理和治疗HMPV感染， 免疫调节。鉴定老年宿主中的分子靶点将指导开发安全且 为所有高危人群提供有效的HMPV疫苗。 此外，这份建议书提供了大量的培训机会，有助于实现我的职业目标， 成为临床科学家和免疫学和传染病的独立首席研究员。

ABSTRACT Human metapneumovirus (HMPV) is a leading cause of lower respiratory infections in young children, immunocompromised persons, and the elderly, resulting in high morbidity and mortality. Few studies have investigated why HMPV is more severe in the elderly. This proposal aims to fill this knowledge gap about HMPV pathogenesis. My preliminary data discovered that aged mice infected with HMPV exhibit delayed viral clearance, increased lung inflammation, and increased CD8+ HMPV-tetramer+ cells co-expressing the inhibitory markers PD-1, TIM-3, and LAG-3. I hypothesize that severe HMPV infection in the elderly is caused by impairment of the CD8+ T cell response. In Aim 1, I will investigate the intrinsic causes of the CD8+ T cell impairment observed in the aged host infected with HMPV using 10X Multiomics studies on murine lung directly ex vivo and syngeneic transplants. 10X Multiomics will elucidate age-related epigenetic changes in CD8+ T cells while syngeneic transplants will transfer young CD8+ T cells into an aged host and vice versa to determine if CD8+ T cells are the primary immune cells causing the impaired immune response to HMPV (i.e. increased weight loss, clinical severity, delayed viral clearance). In Aim 2, I will investigate extrinsic causes of the CD8+ T cell impairment, namely by alveolar macrophages (AMs). I will use a 21-color multispectral flow cytometry panel to enumerate M1 and M2 macrophage populations in the aged host. In vitro co-culture and transwell assays of AMs and CD8+ T cells will determine if AMs directly impair CD8+ T cells. Selective depletion of AMs in aged mice and adoptive transfer of young macrophages will determine how AMs contribute to the impaired immune response in the aged host. 10X Multiomics will also be performed in this aim to investigate the age-related epigenetic changes in AMs that may contribute to their aberrant M2 accumulation, which I have also observed in my preliminary data. This proposal aims to understand the mechanistic differences in the aged host response to HMPV, which will help elucidate why HMPV infection in the elderly is more severe. These studies have the potential to translate into the clinical setting and contribute to better management and treatment for HMPV infection, such as immunomodulation. Identifying molecular targets in the aged host will guide development of a safe and effective vaccine against HMPV for all at-risk populations. In addition, this proposal has tremendous training opportunities, contributing towards my career goals of becoming a clinician scientist and independent principal investigator in immunology and infectious disease.