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造成相当大的发病率和死亡率。虽然接种疫苗被认为是 为了提供保护，目前的季节性疫苗引起的抗体反应通常是短暂的。在……里面 相比之下，自然流感感染可诱导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相联系的免疫机制和途径 目前仍不清楚，尤其是在人类中。动物模型的研究表明，流感感染，但不是 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在当地保留了很长时间，有证据表明，针对流感的TRM要多得多 在预防流感感染方面比他们的脾对应物更有效。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内产生特异性抗体 挑战。鉴于这些观察表明流感特异性肺BRM在前线的关键作用 在再次感染时，肺BRM分化为抗体产生细胞的机制尚不清楚。我们 假设流感特异性肺CD4TRM的一个子集(S)表现出类似于T滤泡辅助分子的特性 (TFH)细胞，并且这个亚群(S)与人肺中流感特异性记忆B细胞相互作用，进行快速局部治疗 AB反应。在这项计划中，我们将利用我们在人类CD4+T细胞亚群方面的广泛专业知识来定义 人肺内CD4TRM中的一个“TFH样”亚群，并确定它们对肺BRM的作用模式。目标1将 确定人肺中“类Tfh”CD4TRM的表型。使用转录本和转录本的细胞索引 表位测序(CITE-SEQ)，我们将全面分析 人肺CD_4~+T细胞差异表达表面标志并鉴定细胞群 富含TFH基因签名。我们还将评估流感特异性CD4TRM的表型。 使用我们最近建立的IRF4检测方法。目标2将全面定义 人肺组织中流感病毒HA特异性B细胞亚群。通过将“类Tfh”的CD4TRM与肺BRM共培养，我们 将分析T细胞是否诱导B细胞分化为产生流感抗体的细胞。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 人肺内主要的T和B细胞亚群负责快速的局部抗体反应。我们预计我们的 研究将增加我们对人类肺局部免疫保护机制的认识，并为 对高效流感疫苗设计的重大洞察。

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.