Strength of TCR:self-pMHC interactions in the periphery instructs CD4+ T help cell responses

项目总结 对于许多致命的疾病，有效的疫苗仍然难以捉摸；因此，关键是我们必须更好地了解 免疫系统对疫苗接种会产生强大的中和抗体反应，以便我们可以增强 在未来的疫苗设计中，这种类型的反应。B细胞是高亲和力抗体的制造者，然而，它是 提供推动B细胞命运所必需的细胞因子和共刺激分子的CD4+T细胞 建立长期的体液免疫。这就是为什么我们更好地了解发展和 参与产生这种反应的特定的CD4+T细胞亚群的功能。在初次感染后或 接种疫苗后，一些活化的CD4+T细胞成为已知的专门提供直接B细胞的特殊亚群 帮助：T滤泡辅助细胞(TFH)。T细胞与TFH细胞命运的关联尚不清楚。我们的新方法 在B6小鼠中利用针对李斯特菌免疫优势LLO表位的CD4+T细胞反应，使用 两个明确的CD4+TCR转基因株和多克隆T细胞。这两个幼稚的T细胞在紧张性信号方面有所不同 通过自身pMHC的TCR识别而介导。具有低紧张性信号的初始CD4+T细胞具有较高的 基础代谢，在最初的体内反应中做出强有力的反应，并发展成Tfh和Tm细胞。相反， 具有高紧张性信号的初始CD4+T细胞基础代谢较低，形成Tfh细胞较少。前提是 这一建议的要点是，TCR：自身pMHC反应性(强直信号)的强度对于建立 基础代谢和随后的转铁蛋白反应。在目标1中，我们将确定是否存在直接关系 强直信号和抗原暴露后TFH的发生之间存在着联系。为此，我们将使用 我们的新型敲入鼠品系，SCN5A+。TH SCN5A电压门控钠通道的表达使我们能够 在不依赖TCR信号的情况下，增加CD4+T细胞的紧张性信号。我们将使用 新发现的2型糖尿病条件性基因敲除等位基因。TFH辅助函数将使用NP-LLO模型进行测试。 在目标2中，我们将研究T细胞代谢如何影响Tfh细胞反应。我们已经确定了甘油 磷酸盐穿梭在LLO-118 T细胞新陈代谢增加中起关键作用。我们现在已经产生了 具有条件基因敲除等位基因mGPD2的小鼠将成为探索这一作用的强大试剂 LLO-118的代谢途径和多克隆的CD4+T细胞反应。这些发现将深化我们的 了解TFH的发展，并可能揭示疫苗设计和自身免疫的治疗靶点。

PROJECT SUMMARY Effective vaccines remain elusive for many deadly diseases; therefore, it is critical that we better understand how the immune system generates a robust, neutralizing antibody response to vaccination so that we may enhance this type of response in future vaccine design. B cells are the producers of high-affinity antibodies, however, it is the CD4+ T cells that provide the cytokines and co-stimulatory molecules necessary to drive this B cell fate and establish long-term humoral immunity. This is why it is critical that we better understand the development and function of specific CD4+ T cell subsets involved in generating this type of response. After a primary infection or vaccination, some activated CD4+ T cells become a specialized subset specifically known to provide direct B cell help: T follicular helper (Tfh) cells. What commits T cells to the Tfh cell fate is still unknown. Our novel approach leverages the CD4+ T cell response against the immunodominant LLO epitope from Listeria in B6 mice, using two defined CD4+ TCR transgenic lines and polyclonal T cells. The two naive T cells differ in their tonic signaling mediated through the TCR recognition of self-pMHC. Naive CD4+ T cells with low tonic signaling have a high basal metabolism, respond robustly in a primary in vivo response, and develop into Tfh and TEM cells. Conversely, naive CD4+ T cells with high tonic signaling have a low basal metabolism, and poorly form Tfh cells. The premise of this proposal is that the strength of TCR:self-pMHC reactivity (tonic signaling) is deterministic for establishing the basal metabolism and the subsequent Tfh response. In Aim 1, we will establish whether a direct relationship exists between tonic signaling and the development of Tfh following antigen exposure. To this end, we will use our novel knock-in mouse line, Scn5a+. Expression of th Scn5a voltage gated sodium channel allows us to increase tonic signaling in CD4+ T cells independent of TCR signaling. We will decrease tonic signaling using a newly developed conditional knockout allele of H-2DM. Tfh helper function will be tested using an NP-LLO model. In Aim 2 we will examine how T cell metabolism influences Tfh cell responses. We have identified the glycerol phosphate shuttle as a key player in the increased metabolism of the LLO-118 T cells. We have now generated a mouse with a conditional knockout allele of mGPD2 which will be a powerful reagent to explore the role of this metabolic pathway in LLO-118 and polyclonal CD4+ T cell responses. These findings will deepen our understanding of Tfh development and may reveal therapeutic targets for vaccine design and autoimmunity.