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

NK 细胞对晚期 HIV 和隐球菌性脑膜炎患者的新型隐球菌的细胞毒性

• 批准号: 10258384
• 负责人: Elizabeth Okafor
• 金额: $ 4.02万
• 依托单位: UNIVERSITY OF MINNESOTA
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-02-01 至 2026-01-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10258384
• 关键词: NK; Cell; Cytotoxicity; Against; Cryptococcus

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.

项目概要/摘要 新型隐球菌是一种机会性真菌病原体，可引起局部和播散性感染 疾病，隐球菌病，发生在免疫功能低下的个体中，例如艾滋病毒感染者。一个生命—— 隐球菌病的威胁性表现是隐球菌性脑膜炎（CM）；中枢神经系统感染 脑膜急性炎症，是艾滋病毒感染者引起脑膜炎的最常见原因。子 撒哈拉非洲地区承担着全球 CM 疾病负担和死亡率的大部分。因为宿主免疫 反应对于清除感染和解决症状至关重要，对宿主有充分的了解 隐球菌感染状态下的免疫反应对于降低发病率和死亡率至关重要。 自然杀伤 (NK) 细胞是一种先天性淋巴免疫细胞，在 CM 中的研究尚未充分。自然杀伤细胞 具有抗原独立的细胞毒性能力，这使得它们非常适合靶向细胞内和 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系统的一个重要方面。 对新型隐球菌的反应，新型隐球菌既是细胞内病原体，也是细胞外病原体。标准抗真菌剂 治疗以病原体为目标，但死亡仍然发生，包括脑脊液培养无菌的人。我的 初步数据表明，低 CSF 浓度的 NK 细胞细胞毒性相关的可溶性分子 与 CM 患者 14 天急性死亡风险增加相关。因此，改善NK 细胞毒活性可能是降低隐球菌死亡率的创新治疗途径。 此外，鉴定与 NK 细胞功能受损相关的基因和通路可能是 调节以提高细胞毒性可能是未来治疗的目标。 我的中心假设是 NK 细胞有助于清除新型隐球菌的真菌，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 感染而导致的激活受体表达减少会破坏其细胞毒性能力。 为了检验中心假设，我提出以下目标： 目标 1 旨在比较天然 NK 细胞 患有 CM 的 HIV 感染者死亡时的细胞毒性和抗体依赖性细胞介导的细胞毒性 诊断后 14 天内以及存活 > 14 天的患者。目标 2 旨在确定患有 CM 的人是否 14天内死亡的人具有高水平的差异表达基因，这些基因涉及衰竭和抑制 与 CM 存活者相比，细胞毒性途径。总的来说，这些发现将提供 首次定量 NK 细胞对新型隐球菌临床分离株的细胞毒性并鉴定 与急性 CM 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信息 与耗竭、细胞因子产生和细胞毒性有关的基因可以在 宿主靶向免疫治疗的未来。