Inflammatory Suppression of Adaptive Immunity by Plasmodium MIF

项目概要 无法获得针对疟原虫的保护性免疫力是疟疾的主要障碍 控制。在之前的资助期间，我们表明宿主细胞因子的疟原虫直系同源物 巨噬细胞迁移抑制因子，称为 PMIF，损害生发中心的形成和 滤泡辅助 T 细胞 (Tfh) 分化，导致记忆 B 和 T 发育减少 细胞。我们通过接种 pmif RNA 重现了伯氏疟原虫菌株中的遗传性 PMIF 缺陷 复制子，延迟了血液阶段的通畅，增强了 Tfh 细胞和生发中心的反应，以及 增强了记忆 CD4 和肝脏驻留的环子孢子特异性 CD8 T 细胞的分化。我们 观察到感染控制得到改善并完全防止再次感染，这一点被复制 来自 pmif RNA 复制子免疫宿主的 CD8 或 CD4 T 细胞的过继转移。我们的数据表明 疟原虫利用具有严格进化保守性的 PMIF 来干扰 免疫记忆。我们提出以下具体目标，以实现更好理解的目标 对疟疾的无效免疫力并为更好的疫苗奠定基础：目标 1. 定义影响 以及 PMIF 中和在宿主对环子孢子 (CSP) 反应中的潜在协同作用 疫苗接种。基于 CSP 的 RTS,S 疫苗观察到的部分免疫力减弱的部分原因是 记忆 T 细胞反应不足。我们假设将 CSP 与 PMIF 疫苗接种结合起来 增加 CSP 的 T 细胞记忆并提供最佳的高级保护。我们将研究这个方法 与沃尔特·里德陆军研究所合作，对小鼠进行 PMIF 免疫 与恶性疟疾疫苗 013 (FMP013) 一起接种于人 CSP 转基因伯氏疟原虫小鼠体内 模型。目标 2. 确定 PMIF 对疟原虫肝期发育的影响。 PMIF 还 通过生存信号传导支持初始子孢子感染和肝期寄生虫发育 肝细胞MIF受体，CD74。我们假设 PMIF 重新编程肝细胞代谢 抑制受感染肝细胞的宿主保护性细胞凋亡。我们将阐明所涉及的途径和 更好地确定肝脏阶段 PMIF 表达对免疫反应发展的影响。目标3。 评估新型小分子 PMIF 抑制剂的治疗潜力。我们开发了一个 一流的小分子 26k，可通过宿主 MIF 受体选择性阻断 PMIF 信号传导 CD74，减少肝脏阶段寄生虫负担，并充分保护小鼠免受脑型疟疾的侵害。我们假设 26k 的药理 PMIF 拮抗可能是预防和肝脏阶段的一种易于处理的方法 治疗，并可能增强免疫记忆反应。对 PMIF 途径的更深入了解将 导致更好的疟疾治疗和疫苗开发策略，并有可能得到推广 其他表达直系同源 MIF 蛋白的寄生虫。

PROJECT SUMMARY The inability to acquire protective immunity against Plasmodium is a major obstacle to malaria control. In the prior funding period, we showed that the Plasmodium orthologue of the host cytokine macrophage migration inhibitory factor, termed PMIF, impairs germinal center formation and the differentiation of T follicular helper cells (Tfh), leading to a reduction in the development of memory B and T cells. We recapitulated genetic PMIF deficiency in a P. berghei strain by vaccination with a pmif RNA replicon, which delayed blood-stage patency, augmented Tfh cell and germinal center responses, and enhanced the differentiation of memory CD4 and liver-resident, circumsporozoite-specific CD8 T cells. We observed improved control of infection and complete protection from re-infection, which was replicated by adoptive transfer of CD8 or CD4 T cells from pmif RNA replicon immunized hosts. Our data indicate that Plasmodium parasites utilize PMIF, which shows strict evolutionary conservation, to interfere with immunologic memory. We propose the following Specific Aims to achieve our goal of better understanding ineffective immunity to malaria and providing a foundation for better vaccines: Aim 1. Define the impact and potential synergy of PMIF neutralization in the host response to circumsporozoite (CSP) vaccination. The partial and waning immunity observed with the CSP-based RTS,S vaccine is due in part to an inadequate memory T cell response. We hypothesize that combining CSP with PMIF vaccination will increase T cell memory to CSP and provide optimal and high-level protection. We will study this approach in collaboration with the Walter Reed Army Institute of Research by immunizing mice against PMIF together with the Falciparum Malaria Vaccine-013 (FMP013) in a human CSP-transgenic P. berghei mouse model. Aim 2. Define the impact of PMIF on Plasmodium liver-stage development. PMIF also supports initial sporozoite infection and liver-stage parasite development by survival signaling through the hepatocellular MIF receptor, CD74. We hypothesize that PMIF re-programs hepatocyte metabolism to inhibit the host-protective apoptosis of infected hepatocytes. We will elucidate the pathways involved and better define the impact of liver-stage PMIF expression on the developing immune response. Aim 3. Evaluate the therapeutic potential of a novel small molecule PMIF inhibitor. We have developed a first-in-class small molecule, 26k, that selectively blocks PMIF signaling through the host MIF receptor CD74, reduces liver-stage parasite burden, and fully protects mice from cerebral malaria. We hypothesize that pharmacologic PMIF antagonism with 26k may be a tractable approach for prophylaxis and liver-stage treatment, and may augment immunologic memory responses. Closer knowledge of the PMIF pathway will lead to better strategies for malaria therapy and vaccine development, and potentially may be generalized to other parasites that express orthologous MIF proteins.