Elucidating the mode of action of "Tfh-like" resident memory CD4+ T cells in human lung

项目摘要 流感感染在世界范围内引起大量发病率和死亡率。虽然疫苗被认为 尽管季节性疫苗不能提供保护，但目前季节性疫苗诱导的抗体反应通常是短暂的。在 相反，自然流感感染诱导针对未来流感病毒的持久保护性免疫 感染.与自然感染的持久保护有关的免疫机制和途径 目前尚不清楚，尤其是在人类中。动物模型的研究表明，流感感染，但不是 用灭活病毒免疫产生流感特异性肺组织驻留记忆T（TRM）细胞。 TRM在当地保留了很长一段时间，有证据表明流感特异性TRM在当地保留的时间要长得多。 比脾脏更有效地保护免受流感感染。感染流感病毒也 诱导肺驻留记忆B（BRM）细胞，在感染后迅速在肺中产生特异性抗体 挑战.尽管这些观察结果表明流感特异性肺BRM在一线的关键作用， 再次感染，肺BRM分化为Ab产生细胞的机制仍然未知。我们 假设流感特异性肺CD 4 TRM亚群显示与T滤泡辅助细胞相似的特性 (Tfh)细胞，并且该亚群与人肺中的流感特异性记忆B细胞相互作用， 抗体应答。在这项提案中，我们将利用我们在人类CD 4 + T细胞亚群方面的广泛专业知识， 人肺CD 4 TRM内的“Tfh样”亚群，并确定其对肺BRM的作用模式。目标1将 定义人肺中“Tfh样”CD 4 TRM的表型。通过使用转录组的细胞索引和 表位测序（CITE-seq），我们将全面分析转录异质性之间 差异表达表面标志物的人肺CD 4 + T细胞，并旨在鉴定细胞群 富含转铁蛋白基因标签我们还将评估流感特异性CD 4 TRM的表型， 通过使用我们最近建立的IRF 4测定法对人肺进行了研究。目标2将全面界定 人肺中流感HA特异性B细胞的亚群。通过将“Tfh样”CD 4 TRM与肺BRM共培养， 将分析T细胞是否诱导B细胞分化为流感Ab产生细胞。我们将进一步 通过阻断几个候选分子来确定辅助机制。因此，我们的研究旨在确定 人肺中负责快速局部Ab应答的主要T和B细胞亚群。我们预计， 这项研究将增加我们对人肺局部免疫保护机制的认识， 对设计有效的流感疫苗有重要的见解。

Project Summary Influenza infections cause substantial morbidity and mortality worldwide. While vaccination is considered to provide protection, the antibody response induced by current seasonal vaccines is generally short-lived. In contrast, natural influenza infection induces durable protective immunity against future influenza virus infections. The immune mechanisms and pathways that are linked with durable protection by natural infection remain unclear particularly in humans. Studies in animal models show that influenza infection, but not immunization with inactivated virus, generates influenza-specific lung tissue-resident memory T (TRM) cells. TRM are retained for a long time locally, and there is evidence that influenza-specific TRM are far more efficient than their splenic counterpart for protection from influenza infection. Infection with influenza virus also induces lung-resident memory B (BRM) cells that rapidly produce specific Abs in the lung following infection challenge. Whereas these observations suggest a key role of influenza-specific lung BRM at the frontline upon re-infection, the mechanism by which lung BRM differentiate into Ab-producing cells remains unknown. We hypothesize that a subset(s) of influenza-specific lung CD4 TRM display properties similar to T follicular helper (Tfh) cells, and that this subset(s) interact with influenza-specific memory B cells in human lung for rapid local Ab response. In this proposal, we will leverage our extensive expertise in human CD4+ T cell subsets to define a “Tfh-like” subset within human lung CD4 TRM, and determine their mode of action on lung BRM. Aim 1 will define the phenotype of “Tfh-like” CD4 TRM in human lung. By using Cellular Indexing of Transcriptomes and Epitopes by Sequencing (CITE-seq), we will comprehensively analyze the transcriptional heterogeneity among human lung CD4+ T cells differentially expressing surface markers, and aim to identify the cell population enriched with the Tfh-gene signature. We will also assess the phenotype of influenza-specific CD4 TRM in human lung by using the IRF4 assay that we have recently established. Aim 2 will comprehensively define the subsets of influenza HA-specific B cells in human lung. By co-culturing “Tfh-like” CD4 TRM with lung BRM, we will analyze whether the T cells induce B cell differentiation into influenza Ab-producing cells. We will further determine the helper mechanism by blocking several candidate molecules. As such, our study aims to identify the major T and B cell subsets in human lung responsible for rapid local Ab response. We anticipate that our study will increase our knowledge in the local immune protection mechanism of human lung and provide significant insight into the design of efficient influenza vaccines.