Mechanisms of vaccine protection against AIDS-associated Cryptococcus infection

摘要 隐球菌病是一种艾滋病定义疾病，也是艾滋病毒感染者中最常见的真菌病。 患者大多数艾滋病患者的真菌性脑膜炎病例是由于感染了全球分布的 真菌病原体新型隐球菌最近的估计表明，新型隐球菌导致> 180，000 艾滋病每年造成15%的死亡，占艾滋病相关死亡的15%。因此，有一个重要的，未满足的 医学需要开发新的治疗方法来对抗这种危及生命的真菌感染。更好地了解 形成对隐球菌免疫的宿主和病原体因素可以告知许多 需要预防性疫苗接种策略和免疫疗法。在最近发表的研究中，我们 已经发现F-box蛋白1（Fbp 1）作为C.新生儿免疫原性。FBP 1是一个 SCFFbp 1 E3连接酶复合物的亚基，泛素介导的蛋白水解途径的关键组分 针对特定蛋白质进行降解。梭缺乏Fbp 1（fbp 1D）的新型变形杆菌突变株， 在体内低毒力而不影响已知毒力因子的表达，表明Fbp 1可能 调节一种新的毒力决定因子。fbp 1D的肺部感染诱导了 CCR 2+单核细胞和增强的CD 8+和CD 4 + T细胞应答的活化。我们发现 这些增强的先天性和适应性免疫应答协同控制C。新生儿感染 肺和两者都是宿主长期生存所必需的。此外， fbp 1D突变体（HK-fbp 1D）作为一种有效的疫苗，可保护两种不同遗传的小鼠， 背景对抗亲本强毒株H99的感染。在本申请中，我们提出了一种 一系列合作研究，以破译Fbp 1如何调节抗隐球菌免疫的激活 并进一步开发fbp 1D作为新型隐球菌病疫苗株的潜力。中央 我们的工作假设是Fbp 1调节特异性靶蛋白的丰度，从而形成 C.新人类我们的首要目标是系统地破译 疫苗诱导的保护机制，并确定和验证特定的Fbp 1调节靶点， 形成C.新人类我们将利用我们的综合专业知识来测试我们的假设， 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 细胞群对fbp 1D感染的保护和HK-fbp 1D疫苗诱导的保护，2） 揭示IFN-g介导的疫苗保护的分子机制，以及3）鉴定和验证Fbp 1- 影响宿主免疫力的调节靶点。总的来说，这些研究将促进我们对 宿主-病原体相互作用参与隐球菌的免疫调节，并可能指导 疫苗和特异性C.新生儿因子，以增强宿主介导的感染控制。

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.