Mechanisms of vaccine protection against AIDS-associated Cryptococcus infection

摘要 隐球菌病是一种定义艾滋病的疾病，也是艾滋病毒感染者最常见的真菌疾病 病人。艾滋病患者中的大多数真菌性脑膜炎病例都是由全球分布的感染引起的 真菌病原体新生隐球菌属。最近的估计表明，新生链球菌导致18万人 每年死亡人数占艾滋病相关死亡人数的15%。因此，有一个重大的，未得到满足的 医学上需要开发新的治疗方法来对抗这种威胁生命的真菌感染。更好地理解 形成对隐球菌免疫的宿主和病原体因素可以促进许多疾病的发展 需要预防性疫苗接种战略和基于免疫的疗法。在最近发表的研究中，我们 已发现F-box蛋白1(FBP1)是新生葡萄球菌免疫原性的调节因子。FBP1是一种 SCFFbp1 E3连接酶复合体的亚基，是泛素介导的蛋白分解途径的关键组成部分 以特定蛋白质为目标进行降解。缺乏fbp1(Fbp1D)的新生隐孢子虫突变株 在体内弱毒力而不影响已知毒力因子的表达，表明FBP1很可能 调节一种新的毒力决定因素。肺部感染fbp1D诱导强健的募集 CCR2+单核细胞和激活增强的CD8+和CD4+T细胞反应。我们发现了 这些增强的先天和获得性免疫反应协同作用，控制新城疫杆菌的感染。 肺脏和肺都是宿主长期生存所必需的。此外，热灭活剂还可用于 Fbp1D突变体(HK-fbp1D)作为一种有效的疫苗保护两种不同基因的小鼠 背景对抗亲本、高毒力菌株H99的感染。在本申请中，我们提出了一种 破译FBP1如何调节抗隐球菌免疫激活的一系列合作研究 进一步挖掘fbp1D作为新型隐球菌病疫苗株的潜力。中环 我们工作的假设是，FBP1调节特定靶蛋白的丰度，进而形成 新生葡萄球菌的免疫原性。我们的首要目标是系统地破译免疫系统 疫苗诱导保护的机制以及识别和验证FBP1调节的特定靶点 塑造新生葡萄球菌的免疫原性。我们将利用我们的综合专业知识来检验我们的假设 三个独立但密切相关的具体目标：1)破译先天免疫的独特贡献 细胞群体对fbp1D感染的保护和HK-fbp1D疫苗诱导的保护，2) 揭示干扰素-g介导的疫苗保护的分子机制；3)鉴定和验证FBP1- 影响宿主免疫力的受调控靶标。总体而言，这些研究将促进我们对 宿主-病原菌相互作用参与了隐球菌的免疫调节，并可能指导设计 新生假单胞菌特定因子的疫苗和抑制剂，以加强宿主对感染的控制。

Abstract Cryptococcosis is an AIDS-defining illness and the most common fungal disease in HIV-infected patients. Most cases of fungal meningitis in AIDS patients are due to infections with the globally distributed fungal pathogen Cryptococcus neoformans. Recent estimates indicate that C.neoformans causes > 180,000 deaths annually and is responsible for 15% of AIDS-related deaths. Thus, there is a significant, unmet medical need to develop new treatments against this life-threatening fungal infection. A better understanding of host and pathogen factors that shape immunity against Cryptococcus can inform the development of much needed preventative vaccination strategies and immune-based therapies. In recently published studies, we have uncovered that F-box protein 1 (Fbp1) acts as a regulator of C. neoformans immunogenicity. Fbp1 is a subunit of the SCFFbp1 E3 ligase complex, a key component of the ubiquitin-mediated proteolytic pathway that targets specific proteins for degradation. The C. neoformans mutant strain lacking Fbp1 (fbp1D) is hypovirulent in vivo without affecting the expression of known virulence factors, indicating that Fbp1 likely regulates a novel virulence determinant. Pulmonary infection with fbp1D induced the robust recruitment of CCR2+ monocytes and the activation of enhanced CD8+ and CD4+ T cell responses. We uncovered that these enhanced innate and adaptive immune responses cooperate to control C. neoformans infection in the lung and are both required for the long-term survival of the host. Moreover, heat-killed preparations of the fbp1D mutant (HK-fbp1D) acted as an effective vaccine and protected mice of two different genetic backgrounds against infection with the parental, highly virulent strain H99. In this application, we propose a series of collaborative studies to decipher how Fbp1 regulates the activation of anti-Cryptococcus immunity and to further exploit the potential of fbp1D as a novel vaccine strain against cryptococcosis. The central hypothesis of our work is that Fbp1 regulates the abundance of specific target proteins, which in turn shape the immunogenicity of C. neoformans. Our overarching goal is to systematically decipher the immune mechanisms of vaccine-induced protection and to identify and validate specific Fbp1-regulated targets that shape the immunogenicity of C. neoformans. We will utilize our combined expertise to test our hypothesis in three independent, but closely related Specific Aims: 1) Decipher the distinct contributions of innate immune cell populations to protection from infection with fbp1D and to HK-fbp1D vaccine-induced protection, 2) Uncover the molecular mechanisms of IFN-g-mediated vaccine protection, and 3) Identify and validate Fbp1- regulated targets that influence host immunity. In aggregate, these studies will advance our understanding of host-pathogen interactions involved in the immune regulation by Cryptococcus and may guide the design of vaccines and inhibitors of specific C. neoformans factors to enhance host-mediated control of infection.