NK Cell Cytotoxicity Against Cryptococcus neoformans in Persons with Advanced HIV and Cryptococcal Meningitis

项目摘要/摘要 摘要新生隐球菌是一种机会性真菌病原体，可引起局部性和播散性。 疾病，隐球菌病，免疫受损的人，例如艾滋病毒携带者。一种生活- 隐球菌病的威胁表现是隐球菌性脑膜炎(CM)；一种中枢神经系统感染 患有急性脑膜炎，是艾滋病毒携带者脑膜炎的最常见原因。子- 撒哈拉非洲承担着全球大多数CM疾病的负担和死亡率。因为宿主免疫 反应对清除感染和消除症状至关重要，对宿主有扎实的了解 为了减少发病率和死亡率，隐球菌感染状态下的免疫反应是必不可少的。 自然杀伤细胞(NK细胞)是一种天然的淋巴免疫细胞，在CM中尚未得到充分的研究。NK细胞 具有不依赖于抗原的细胞毒能力，使其成为靶向细胞内和 细胞外病原体。NK细胞的这一关键特征可能使它们成为免疫中的一个重要方面 对新生葡萄球菌的反应，这是一种细胞内和细胞外的病原体。标准抗真菌药 治疗针对病原体，但仍然会发生死亡，包括在脑脊液无菌培养的人中。我的 初步数据显示，低浓度脑脊液中的NK细胞对细胞的杀伤作用与可溶性分子有关 与CM患者急性14天死亡的风险增加有关。因此，改善NK 细胞毒活性可能是降低隐球菌死亡率的一种创新治疗途径。 此外，与NK细胞功能受损有关的基因和通路的鉴定可能是 调节以提高细胞毒性可能成为未来治疗的靶点。 我的中心假设是，NK细胞有助于清除新生葡萄球菌的真菌，但 NK细胞耗竭、细胞因子产生受损、抑制性受体增加以及 由于潜在的HIV感染，激活受体的表达减少，破坏了它们的细胞毒能力。 为了验证中心假设，我提出了以下目标：目标1试图将自然杀伤细胞 HIV感染者死亡后的细胞毒性和抗体依赖细胞介导的细胞毒作用 确诊后14天内和存活14天的患者。目标2试图确定患有CM的人是否 在14天内死亡的人有高水平的差异表达基因，涉及疲劳和抑制 与存活的CM患者相比，细胞毒性途径。总而言之，这些发现将提供 NK细胞对新生葡萄球菌临床分离株杀伤活性的首次定量及鉴定 与急性心肌梗塞死亡率相关的差异表达基因。这些信息将为我们提供具体的 参与疲劳、细胞因子产生和细胞毒性的基因，这些基因可能在 宿主靶向免疫治疗的未来。

PROJECT SUMMARY / ABSTRACT Cryptococcus neoformans is an opportunistic fungal pathogen that causes localized and disseminated disease, cryptococcosis, in immunocompromised individuals, such as in people living with HIV. A life- threatening manifestation of cryptococcosis is cryptococcal meningitis (CM); a central nervous system infection with acute inflammation of the meninges and the most common cause of meningitis in those with HIV. Sub- Saharan Africa carries the majority of the global CM disease burden and mortality. Because the host immune response is crucial to clearance of the infection and resolution of symptoms, a solid understanding of the host immune response in the state of cryptococcal infection is essential in order to reduce morbidity and mortality. Natural killer (NK) cells are an innate lymphoid immune cell that has been understudied in CM. NK cells have antigen independent cytotoxic ability that render them ideal for targeting both intracellular and extracellular pathogens. This key feature of NK cells could make them an important aspect in the immune response to C. neoformans, which is both an intracellular and extracellular pathogen. Standard antifungal therapy targets the pathogen, yet mortality still occurs, including among persons with sterile CSF cultures. My preliminary data has shown that low CSF concentrations of NK cell cytotoxicity associated soluble molecules are associated with increased risk of acute 14-day mortality in persons with CM. Therefore, improving NK cytotoxic activity may be an innovative therapeutic pathway toward reducing cryptococcal mortality. Additionally, the identification of genes and pathways implicated in impaired NK cell function that could be modulated to improve cytotoxicity could be targets for future therapeutics. My central hypothesis is that NK cells contribute to fungal clearance of C. neoformans, but that a combination of NK cell exhaustion, impaired cytokine production, increased inhibitory receptors, and decreased activating receptor expression due to the underlying HIV infection disrupts their cytotoxic abilities. To test the central hypothesis, I am proposing the following Aims: Aim 1 seeks to compare NK cell natural cytotoxicity and antibody-dependent cell mediated cytotoxicity between HIV-infected persons with CM who die within 14-days of diagnosis and those who survive >14 day. Aim 2 seeks to determine if persons with CM who die within 14-days have high levels of differentially expressed genes involved in exhaustion and inhibition of cytotoxicity pathways when compared to persons who survive CM. Collectively, these findings will provide the first quantification of NK cell cytotoxicity against clinical isolates of C. neoformans and the identification of differentially expressed genes associated with acute CM mortality. This information will provide us with specific genes that are involved in exhaustion, cytokine production, and cytotoxicity that could be modulated in the future with host targeted immunotherapy.