Regulation and function of immune suppressive T cells in aging

摘要 最近的一些研究发现，主动免疫抑制机制随着年龄的增长而逐渐发展。 并抑制免疫功能。重要的是，这些数据还表明，老年人的免疫系统 如果这些机制得到控制，就可以恢复。我们的新数据表明，一种新的种群 产生高水平IL-10的免疫抑制CD4+T细胞在小鼠和 人类。这些细胞是维持老年小鼠体内高水平的系统性IL-10所必需的。 重要的是，阻断老年小鼠的IL-10信号可恢复疫苗驱动的生发中心B细胞 反应与在幼鼠身上观察到的水平相似。流式细胞仪和单细胞基因组分析显示 这些产生IL-10的CD4+T细胞中的大多数带有T滤泡辅助细胞(TFH)的标志，这是一种细胞类型 对抗体的产生至关重要，因此，我们将它们称为Tfh10细胞。Tfh10表达几个Tfh特异性基因， 但它们与典型的Tfh不同，除了IL-10外，还表达几种Th1转录本， 提示T细胞分化状态改变。重要的是，我们还发现抗原特异的Tfh10细胞 在老年小鼠接种疫苗后第8天就出现了，但在年轻小鼠身上没有出现。我们的数据也将这些细胞 由于IL-6和IL-21是Tfh10细胞在衰老小鼠体内积累所独立需要的，因此具有“炎症”作用。 总之，我们的初步数据支持我们的总体假设，即IL-6和IL-21促进发育和 产生IL-10的Tfh细胞的存活和IL-10对B细胞的信号传递是限制持久疫苗的关键 回应。这些假设将在三个目标中得到检验。在sp.Aim1中，我们将确定(S) 控制Tfh10细胞随增龄的发育和蓄积。利用流式细胞术和SC基因组学 分析抗原对接种疫苗的特异性反应，我们将检验以下假设：(I)Tfh10细胞出现 从疫苗接种后早期需要IL-6的改变的分化过程中；(Ii)IL-21而不是IL-6促进 拮抗Bim对Tfh10细胞长期存活的影响在Sp.Aim2中，我们将确定细胞作用轨迹 和IL-10在疫苗驱动的衰老保护性免疫中的作用，假设如下：(I)直接IL-10 向B细胞发出的信号限制了它们对疫苗接种的反应(II)过多的IL-10抑制Long-10的产生 活的浆细胞(PC)；和(Iii)老化的Tfh10细胞被要求限制疫苗诱导的年轻人的B细胞反应 老鼠。在Sp.Aim3中，我们将确定IL-10在控制老年非老年人流感疫苗应答中的作用。 人类灵长类动物，通过在标准时间注射有效的恒河猴IL-10R-Fc(或对照Ig) 流感疫苗接种和(I)分析疫苗引起的免疫反应以及局部和系统免疫反应 炎症；以及(Ii)将这些反应与对后续流感挑战的抵抗力相关联。总体而言，这 这项研究非常有意义和创新性，因为它解决了衰老免疫学的两个重要方面， 通过在细胞和分子水平上提供对推动复杂的 “发炎”与免疫抑制的关系。此外，它还可以具有重要的潜力 翻译含义，因为我们将测试短暂阻断疫苗上IL-10信号的有效性 老年恒河猴的反应性。

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.