Lipid-mediated fungal pathogenesis

脂质介导的真菌发病机制

• 批准号: 9305840
• 负责人: Maurizio Del Poeta
• 金额: $ 58.01万
• 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/9305840
• 关键词: Achievement; Acquired Immunodeficiency Syndrome; Adverse effects; Antifungal Agents; Biochemical; Biology; Blood Circulation; CD4 Positive T Lymphocytes; Cells; Cryptococcus gattii; Cryptococcus neoformans; Cryptococcus neoformans infection; 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; killings; 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隐球菌的致病机制 新型隐球菌 (Cn) 专注于 Cn 糖脂如何调节真菌毒力和宿主免疫反应。 Cn 是一种真菌病原体，进入肺部并通过血流传播后，会导致 易感患者患上危及生命的脑膜脑炎，导致高发病率和死亡率。 目前针对这种疾病的治疗方法可能会产生无法忍受的剂量限制性副作用。1因此，新的治疗方法 有必要采取策略更好地控制与隐球菌病相关的高死亡率。 尽管疫苗被誉为过去公共卫生领域最伟大的成就之一 本世纪，针对隐球菌病和真菌感染的安全有效的疫苗的开发 一般来说，一直是一个主要障碍，主要是由于缺乏对支撑机制的了解 保护性免疫力。此外，真菌疫苗需要在免疫缺陷的情况下有效， 比如艾滋病患者CD4+T细胞淋巴细胞减少，因为免疫缺陷患者最多 易受隐球菌病和其他侵袭性真菌感染。 在之前的研究中，我们删除了甾醇葡萄糖苷酶1（Sgl1）基因，得到的突变体（Δsgl1）是 高度富含甾醇糖苷 (SG)（图 3 和 4），否则在野生型 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，易于刺激 2-4 我们发现 Cn Δsgl1 突变体在小鼠模型中不具有致病性（图 8A），并且 鼻内给药后，突变细胞在肺部环境中被迅速杀死（图8B）。非常 有趣的是，接受 Cn Δsgl1 突变体的小鼠在受到剧毒 Cn H99 或格特梭菌攻击时受到保护 265 株（图 10），即使当小鼠 CD4+ T 细胞耗尽时，这种保护仍然持续（图 12）。基于 根据这些观察结果，我们假设 Cn Sgl1 是真菌毒力的主要调节因子 调节 SG 的水平，进而刺激宿主的免疫反应 隐球菌病。为了检验这一假设，我们提出以下目标： 目标 1. 将 Sgl1 确立为真菌中 SG 的关键调节因子。在此目标 1 中，我们将： 1A) 研究 Sgl1的生化特性； 1B) 研究 Sgl1 在调节 SG 和毒力中的作用。 目标 2. 确定宿主针对 Δ sgl1 的免疫机制。为了这个目标，我们将： 2A) 检查 导致 Δ sgl1 清除的免疫反应； 2B) 检查保护的免疫反应 Δ sgl1免疫小鼠继发感染；和 2C) 使用耗尽方法来检查 初始清除 (2A) 和防止继发攻击感染 (2B) 的细胞要求。 该提案将为真菌 SG 调节的作用和机制提供初步见解。 一种重要的人类真菌病原体，即 Cn 的病理生物学。它们也有可能导致 开发新的抗真菌策略来预防或/和治疗侵袭性真菌感染 免疫功能健全和免疫功能低下的宿主。