Regulation and function of immune suppressive T cells in aging

摘要 最近的几项研究发现，主动免疫抑制机制随着年龄的增长而逐渐发展 抑制免疫功能重要的是，这些数据还表明，老化的免疫系统 如果这些机制得到控制，就可以恢复。我们的新数据表明， 产生高水平IL-10的免疫抑制性CD 4 + T细胞随着年龄的增长而积累， 人类这些细胞是维持老年小鼠中存在的高水平全身性IL-10所必需的。 重要的是，阻断老年小鼠中的IL-10信号传导可恢复其疫苗驱动的生发中心B细胞 反应类似于在年轻小鼠中观察到的水平。流式细胞术和单细胞基因组学分析显示， 这些产生IL-10的CD 4 + T细胞中的大多数携带T滤泡辅助细胞（Tfh）的标记， 对于抗体的产生至关重要，因此，我们将其称为Tfh 10细胞。Tfh 10表达几种Tfh特异性基因， 但是它们与典型的Tfh明显地聚集，并且除了IL-10， 表明T细胞分化状态改变。重要的是，我们还发现抗原特异性Tfh 10细胞 在老年小鼠中，早在接种后第8天就出现，但在年轻小鼠中不出现。我们的数据还将这些细胞 IL-6和IL-21是Tfh 10细胞在老年小鼠中积累所独立需要的。 总之，我们的初步数据推动了我们的总体假设，即IL-6和IL-21促进了发育， 产生IL-10的Tfh细胞的存活和IL-10向B细胞的信号传导对于限制疫苗的持久性是关键的 应答这些假设将在3个目标中进行测试。在Sp.Aim1中，我们将确定 控制Tfh 10细胞随年龄的发育和积累。使用流式细胞术和sc基因组学， 为了分析对疫苗接种的抗原特异性应答，我们将检验以下假设：（i）Tfh 10细胞产生 来自需要IL-6的疫苗接种后早期改变的分化过程;（ii）IL-21，而不是IL-6，促进 拮抗Bim.在Sp.Aim2中，我们将确定作用的细胞位点 以及IL-10在衰老中对疫苗驱动的保护性免疫的功能，具有以下假设：（i）直接IL-10在衰老中对疫苗驱动的保护性免疫的作用。 10向B细胞的信号传导限制了它们对疫苗接种的反应（ii）过量的IL-10抑制长- 活的浆细胞（PC）;和（iii）需要老化的Tfh 10细胞来限制年轻人中疫苗诱导的B细胞应答 小鼠在Sp.Aim3中，我们将确定IL-10在控制老年非流感患者流感疫苗应答中的作用。 人灵长类动物，通过在标准剂量时给予经验证的恒河猴IL-10 R-Fc（或对照IG） 流感疫苗接种和（i）分析疫苗引起的免疫应答，以及局部和全身免疫应答。 炎症;和（ii）将这些应答与对随后的流感攻击的抗性相关联。总体而言，这 研究是非常重要和创新的，因为它解决了衰老免疫学的两个重要方面， 通过提供深入的分析，在细胞和分子水平上，驱动复杂的 “炎症”与免疫抑制的关系。此外，它还具有重要的潜力， 翻译的影响，因为我们将测试瞬时阻断IL-10信号转导对疫苗的功效。 老年恒河猴的反应。

ABSTRACT Several recent studies uncovered that active immune suppressive mechanisms develop progressively in aging and dampen immune function. Importantly, these data also demonstrate that the aged immune system is amenable to restoration, if these mechanisms are controlled. Our new data demonstrated that a novel population of immune suppressive CD4+ T cells that produce high levels of IL-10 accumulates with age in both mice and humans. These cells are required for maintaining the high levels of systemic IL-10 present in aged mice. Importantly, blockade of IL-10 signaling in aged mice restores their vaccine-driven germinal center B cell responses similar to levels observed in young mice. Flow cytometric and single cell genomics analyses show that the majority of these IL-10-producing CD4+ T cells bear markers of T follicular helper (Tfh) cells, a cell type critical for antibody production, and thus, we refer them as Tfh10 cells. Tfh10 express several Tfh-specific genes, but they cluster distinctly from canonical Tfh and also express several Th1 transcripts, in addition to IL-10, suggesting an altered T cell differentiation state. Importantly, we also found that antigen-specific Tfh10 cells emerge as early as day 8 after vaccination in aged mice, but not in young mice. Our data also link these cells with “inflammaging” as IL-6 and Il-21 are independently required for the accumulation of Tfh10 cells in aged mice. Together, our preliminary data drive our overall hypothesis that IL-6 and IL-21 promote the development and survival, respectively, of IL-10-producing Tfh cells, and IL-10 signaling to B cells is critical to limit durable vaccine responses. These hypotheses will be tested in 3 aims. In Sp.Aim1, we will determine the mechanism(s) that control the development and accumulation of Tfh10 cells with age. Using flow cytometry and sc genomics to analyze the antigen-specific response to vaccination, we will test the following hypotheses: (i) Tfh10 cells arise from an altered differentiation process early after vaccination that requires IL-6; (ii) IL-21, but not IL-6, promotes the long-term survival of Tfh10 cells by antagonizing Bim. In Sp.Aim2, we will identify the cellular loci of action and function of IL-10 on vaccine-driven protective immunity in aging, with the following hypotheses: (i) direct IL- 10 signaling to B cells limits their response to vaccination (ii) excessive IL-10 suppresses generation of long- lived plasma cells (PCs); and (iii) aged Tfh10 cells are required to limit vaccine-induced B cell responses in young mice. In Sp.Aim3, we will determine the role of IL-10 in controlling influenza vaccine responsiveness in aged non- human primates, by administering a validated Rhesus macaque IL-10R-Fc (or control Ig) at the time of a standard influenza vaccination and (i) analyzing vaccine-elicited immune responses, as well as local and systemic inflammation; and (ii) correlating these responses with resistance to a subsequent Flu challenge. Overall, this research is highly significant and innovative because it tackles two important aspects of the immunology of aging, by providing in-depth analyses, at the cellular and molecular level, of the mechanisms driving the intricate relationship between “inflammaging” and immune suppression. In addition, it can have important potential translational implications, as we will test the efficacy of transient blockade of IL-10 signaling on vaccine responsiveness in aged Rhesus macaques.