Lipid-mediated fungal pathogenesis

脂质介导的真菌发病机制

• 批准号: 9517734
• 负责人: Maurizio Del Poeta
• 金额: $ 58.19万
• 依托单位: STATE UNIVERSITY NEW YORK STONY BROOK
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-07-01 至 2021-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9517734
• 关键词: Achievement; Acquired Immunodeficiency Syndrome; Adverse effects; Antifungal Agents; Biochemical; Biology; Blood Circulation; CD4 Positive T Lymphocytes; Cells; Cryptococcosis; Cryptococcus gattii; Cryptococcus neoformans; Development; Disease; Dose-Limiting; Environment; Fungal Vaccines; Genes; Glycolipids; Goals; Human; Immune; Immune response; Immunity; Immunize; Immunocompetent; Immunocompromised Host; Immunologic Deficiency Syndromes; In Vitro; Infection; Intranasal Administration; Knowledge; Lead; Life; Lipids; Lung; Lymphopenia; Mediating; Meningoencephalitis; Morbidity - disease rate; Mus; Mycoses; Organism; Pathogenesis; Pathogenicity; Patients; Property; Public Health; Role; Secondary to; Sterols; Testing; Therapeutic; Vaccines; Virulence; Virulence Factors; Virulent; base; fungus; glucosidase; insight; microorganism; mortality; mouse model; mutant; novel; pathogen; prevent; secondary infection; sterol glucoside; treatment strategy

ABSTRACT The long-term goal of this proposal is to study mechanism(s) of pathogenicity of Cryptococcus neoformans (Cn) focusing on how Cn glycolipids regulate fungal virulence and the host immune response. Cn is a fungal pathogen that, upon entering the lung and disseminating through the bloodstream, causes a life-threatening meningo-encephalitis in susceptible patients, leading to high morbidity and mortality. Current therapies for this disease can have intolerable and dose-limiting side effects.1 Thus, new treatment strategies are warranted to better control the high mortality associated with cryptococcosis. Although vaccines have been hailed as one of the greatest achievements in public health during the past century, the development of safe and efficacious vaccines against cryptococcosis, and fungal infections in general, has been a major hurdle mainly due to the lack of knowledge about the mechanisms that underpin protective immunity. Additionally, fungal vaccines need to be effective in conditions of immunodeficiency, such as CD4+ T cell lymphopenia in AIDS patients, because immunodeficient patients are the most susceptible to cryptococcosis and other invasive fungal infections. In previous studies, we deleted the sterol-glucosidase 1 (Sgl1) gene and the resulting mutant (Δsgl1) is highly enriched in sterol glucosides (SGs) (Fig. 3 and 4), which are otherwise not detectable in wild-type Cn cells. SGs are glycolipids present in a variety of fungi and other microorganisms and are prone to stimulate host immunity.2-4 We found that the Cn Δsgl1 mutant is not pathogenic in a mouse model (Fig. 8A) and, upon intranasal administration, the mutant cells are rapidly killed in the lung environment (Fig. 8B). Very interestingly, mice receiving Cn Δsgl1 mutant are protected when challenged with virulent Cn H99 or C. gattii 265 strains (Fig. 10), and this protection persists even when mice are CD4+ T cell depleted (Fig. 12). Based on these observations, we hypothesize that Cn Sgl1 is a major regulator of fungal virulence by modulating the level of SGs, which in turn stimulate the host immune response against cryptococcosis. To test this hypothesis we propose the following aims: Aim 1. To establish Sgl1 as a key regulator of SGs in fungi. In this aim 1 we will: 1A) study the biochemical properties of Sgl1; and 1B) study the role of Sgl1 in regulating SGs and virulence. Aim 2. To determine the host immune mechanisms against Δ sgl1. In this aim we will: 2A) examine the immune response leading to Δ sgl1 clearance; 2B) examine the immune response protecting the Δ sgl1-immunized mice to secondary infection; and 2C) use depletion approaches to examine the cellular requirement for initial clearance (2A) and protection from secondary challenge infection (2B). This proposal will provide the first insights in the role and mechanisms by which fungal SGs regulate the patho-biology of an important human fungal pathogen, namely Cn. They will also potentially lead to the development of novel antifungal strategies to prevent or/and treat invasive fungal infections in immunocompetent and immunocompromised hosts.

抽象的 该提案的长期目标是研究加密赛的致病性机制 Neoformans（CN）的重点是CN糖脂如何调节真菌病毒和宿主免疫响应。 CN是一种真菌病原体，进入肺部并通过血液传播时，会导致 易感患者的脑膜脑膜炎威胁生命，导致高发病率和死亡率。 当前对这种疾病的疗法可能具有插曲和剂量限制的副作用。1，新疗法 必须采取策略来更好地控制与隐球菌病相关的高死亡率。 尽管过去被誉为疫苗是公共卫生中最大的成就之一 世纪，开发针对隐球菌病的安全有效疫苗，以及在 一般，主要是由于缺乏对基础机制的知识的主要障碍 保护性免疫史。此外，真菌疫苗需要在免疫缺陷的情况下有效 例如AIDS患者的CD4+ T细胞淋巴细胞减少症，因为免疫缺陷患者是最大的 容易受到隐球菌病和其他侵入性真菌感染的影响。 在先前的研究中，我们删除了固醇 - 葡萄糖苷酶1（SGL1）基因，所得突变体（ΔSGL1）为 高度富集固醇糖苷（SGS）（图3和4），否则它们在野生型CN中无法检测到 细胞。 SG是存在于多种真菌和其他微生物中的糖脂，很容易刺激 2-4我们发现CNΔSGL1突变体在小鼠模型中不是致病性（图8A），并且在 鼻内给药，突变细胞在肺部环境中迅速杀死（图8B）。非常 有趣的是，接受CNΔSGL1突变体的小鼠在用毒性CN H99或C. gattii挑战时受到保护 265菌株（图10），即使小鼠是CD4+ T细胞耗尽的（图12），此保护仍然存在。基于 在这些观察结果上，我们假设CN SGL1是真菌病毒的主要调节剂 调节SG的水平，进而刺激宿主免疫反应针对 隐球菌病。为了检验这一假设，我们提出以下目的： 目标1。建立SGL1作为真菌中SGS的关键调节器。在此目标1中，我们将：1A）研究 SGL1的生化特性； 1b）研究SGL1在控制SG和病毒中的作用。 目标2。确定针对δSGL1的宿主免疫机制。在此目标中，我们将：2a）检查 导致ΔSGL1清除率的免疫反应； 2b）检查保护的免疫反应 ΔSGL1向继发感染释放的小鼠；和2C）使用部署方法检查 细胞要求（2a）和免受继发性挑战感染的保护（2B）。 该提案将为真菌SGS调节的角色和机制提供第一个见解 重要人类真菌病原体的病原生物学，即CN。他们还可能导致 制定预防或/和治疗侵入性真菌感染的新型抗真菌策略 免疫能力和免疫组合的宿主。