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.

摘要 本提案的长期目标是研究隐球菌的致病机制 新形式（Cn）的重点是如何Cn糖脂调节真菌的毒力和宿主的免疫反应。 CN是一种真菌病原体，一旦进入肺部并通过血流传播， 脑膜脑炎是一种危及生命的易感病，导致高发病率和死亡率。 目前针对这种疾病的治疗可能具有不可耐受和剂量限制性的副作用。1因此，新的治疗方法 有必要采取策略以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， 世纪以来，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，一直是一个主要的障碍，主要是由于缺乏知识的机制，支持 保护性免疫此外，真菌疫苗需要在免疫缺陷条件下有效， 如艾滋病患者的CD 4 + T淋巴细胞减少症，因为免疫缺陷患者最 易患隐球菌病和其他侵袭性真菌感染。 在以前的研究中，我们删除了甾醇葡萄糖苷酶1（Sgl 1）基因，产生的突变体（Δ sgl 1）是 高度富集甾醇葡糖苷（SG）（图3和4），否则在野生型Cn中检测不到 细胞SG是存在于各种真菌和其他微生物中的糖脂，并且易于刺激 2 -4我们发现Cn Δ sgl 1突变体在小鼠模型中不是致病性的（图8A）， 鼻内给药后，突变细胞在肺环境中被迅速杀死（图8B）。非常 有趣的是，接受Cn Δ sgl 1突变体的小鼠在用毒性Cn H99或C.格特隐 265株（图10），并且即使当小鼠被CD 4 + T细胞耗尽时，这种保护也持续存在（图12）。基于 根据这些观察，我们假设Cn Sgl 1是真菌毒力的主要调节因子， 调节SGs的水平，从而刺激宿主免疫应答， 隐球菌病为了检验这一假设，我们提出以下目标： 目标1。确定Sgl 1是真菌中SGs的关键调控因子。在这个目标1中，我们将：1A）研究 B）研究Sgl 1在调节SGs和毒力中的作用。 目标二。确定宿主对Δ sgl 1的免疫机制。在这方面，我们将：2A）检查 导致Δ sgl 1清除的免疫应答; 2B）检查保护 Δ sgl 1免疫的小鼠继发感染;和2C）使用耗竭方法来检查 初始清除（2A）和保护免受二次攻击感染（2B）的细胞需要。 这一建议将提供真菌SGs调节细胞增殖的作用和机制的第一个见解。 一种重要的人类真菌病原体，即Cn的病理生物学。它们还可能导致 开发新的抗真菌策略，以预防或/和治疗侵袭性真菌感染， 免疫活性和免疫受损宿主。