Functionally distinct human CD4 T cell responses to novel evolutionarily selected M. tuberculosis antigens

功能独特的人类 CD4 T 细胞对新型进化选择的结核分枝杆菌抗原的反应

• 批准号: 10735075
• 负责人: Joel D. Ernst
• 金额: $ 85.51万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-07-01 至 2028-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10735075
• 关键词: Adult; Aftercare; Antibodies; Antigen Presentation; Antigenic Variation; Antigens; Bar Codes; Biological Assay; CD4 Positive T Lymphocytes; Cell physiology; Characteristics; Cytoprotection; DNA; Defect; Development; Disease; Elements; Epitopes; Exhibits; Frequencies; Gene Expression Profile; Genome; Goals; Human; IL17 gene; Immune; Immune response; Immunity; Immunology; Individual; Infection; Interferon Type II; Knowledge; M. tuberculosis genome; Memory; Modeling; Mus; Mycobacterium tuberculosis; Mycobacterium tuberculosis antigens; Open Reading Frames; Participant; Peptide Library; Peptides; Phenotype; Phylogenetic Analysis; Population; Property; Proteome; Specificity; T cell response; T memory cell; T-Lymphocyte; T-Lymphocyte Epitopes; Testing; Tuberculosis; Tuberculosis Vaccines; Work; active method; comparative genomics; disorder prevention; genomic locus; human morbidity; human mortality; innovation; insight; neoplastic cell; new technology; next generation sequencing; novel; pathogen; pressure; prevent; receptor expression; response; transcription factor; transmission process; tuberculosis immunity; vaccine development

Although CD4 T cells are essential for immunity to tuberculosis (TB), the features of CD4 T cells that provide protective immunity are not well understood. This knowledge gap is due in part to limited knowledge of the M. tuberculosis (Mtb) antigens that induce protective immune responses. In other pathogens, immune recognition of some antigens provides protection, while recognition of other antigens does not. Likewise in other pathogens, the antigenic targets of protective immunity undergo diversifying evolutionary selection to generate antigenic variation and escape immune recognition. We hypothesized that these principles apply to Mtb, and in earlier studies we made the unexpected discovery that the commonly-studied antigenic targets of human T cells (epitopes) in Mtb are hyperconserved; they are the most conserved elements of the Mtb genome. We then sought to find exceptions, and combined comparative genomics of phylogenetically diverse strains of Mtb with experimental immunology. This led to our discovery of seven novel Mtb antigens (that we term Mtb Rare Variable Antigens; RVA) that are recognized by human T cells and exhibit evidence of evolutionary diversifying selection. Together, these results suggest that human T cell recognition of RVA is detrimental to Mtb and that recognition of conserved 'classical' Mtb antigens is not detrimental to Mtb. We recently studied CD4 T cells from healthy Quantiferon-TB positive (QFT+) recent close contacts of infectious cases of TB, and discovered that RVA induce CD4 T cells characterized by dominant interleukin 17 responses and expression of the lineage-defining transcription factor RORγt, in contrast to CD4 T cells that recognize classical Mtb antigens and exhibit interferon gamma responses and expression of T-bet. These results indicate that human CD4 T cells that recognize RVA are functionally distinct from those that recognize conserved antigens, and we hypothesize that T cells that recognize RVA provide protection against active TB, as indicated by their evolutionary selection. In this project, we will use innovative assays to intensively characterize CD4 T cells from QFT+ adults by comparing the features of CD4 T cells that recognize RVA versus classical Mtb antigens. We will compare their functional responses, longitudinal memory phenotypes, and extent of differentiation. We will also employ an innovative new platform developed by our team, using DNA barcoded peptide epitopes and next generation sequencing to test the hypothesis that associations between CD4 T cell antigen specificity and certain functional responses are widespread in Mtb. To determine the significance of RVA in protective immunity to TB, we will compare CD4 T cells that recognize RVA vs classical Mtb antigens in adults with active TB and those with 'controlled' (or latent) TB. We will also test the hypothesis that defects in RVA-specific CD4 T cells are primary and do not reverse with treatment of active TB. The long term objective of this project is to inform development of TB vaccines that prevent progression to active TB disease, the form that causes human morbidity and mortality, and the form that is responsible for TB transmission.

虽然CD 4 T细胞对于结核病（TB）的免疫是必不可少的，但提供免疫功能的CD 4 T细胞的特征并不重要。 保护性免疫力还没有得到很好的理解。这种知识差距部分是由于对M. 结核病（Mtb）抗原可诱导保护性免疫反应。在其他病原体中，免疫识别 一些抗原的识别提供保护，而其他抗原的识别则不能。同样在其他病原体中， 保护性免疫的抗原靶点经历多样化的进化选择以产生抗原性， 变异和逃避免疫识别。我们假设这些原则适用于结核病，在早期 研究中，我们意外地发现，通常研究的人类T细胞的抗原靶点 Mtb中的表位（表位）是高度保守的;它们是Mtb基因组中最保守的元件。然后我们 试图找到例外情况，并结合比较基因多样性的结核分枝杆菌菌株的基因组学， 实验免疫学这导致我们发现了七种新的Mtb抗原（我们称之为Mtb稀有可变抗原 抗原; RVA），其被人类T细胞识别并表现出进化多样化选择的证据。 总之，这些结果表明，人T细胞对RVA的识别对Mtb是有害的， 保守的“经典”Mtb抗原对Mtb无害。我们最近研究了来自健康人的CD 4 T细胞， Quantiferon-TB阳性（QFT+）最近密切接触结核病感染病例，并发现RVA诱导 以显性白细胞介素17应答和谱系定义因子表达为特征的CD 4 T细胞 转录因子RORγt，与识别经典Mtb抗原并表现出干扰素的CD 4 T细胞相反， γ反应和T-bet的表达。这些结果表明，识别RVA的人CD 4 T细胞 在功能上与那些识别保守抗原的T细胞不同，我们假设， 认识到RVA提供针对活动性TB的保护，如它们的进化选择所示。在这个项目中， 我们将使用创新的检测方法，通过比较QFT+成人的CD 4 T细胞特征， 识别RVA与经典Mtb抗原的CD 4 T细胞。我们将比较他们的功能反应， 纵向记忆表型和分化程度。我们还将采用创新的新平台 由我们的团队开发，使用DNA条形码肽表位和下一代测序来测试 假设CD 4 T细胞抗原特异性和某些功能反应之间的关联是 在MTB中广泛存在。为了确定RVA在结核病保护性免疫中的重要性，我们将比较CD 4 T细胞亚群， 在患有活动性TB的成年人和患有“控制”（或潜伏）的成年人中识别RVA与经典Mtb抗原的细胞 TB.我们还将检验这样的假设，即RVA特异性CD 4 T细胞的缺陷是原发性的，并且不会随着RVA的出现而逆转。 治疗活动性结核病。该项目的长期目标是为结核病疫苗的开发提供信息， 预防进展为活动性结核病，活动性结核病是导致人类发病和死亡的形式， 是结核病传播的罪魁祸首