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 这项建议的长期目标是研究隐球菌致病的机制(S) 新生杆菌(CN)主要研究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，当进入肺部并通过血液传播时，会导致 一种危及生命的脑膜脑炎易感患者，导致高发病率和高死亡率。 目前治疗这种疾病的方法可能会产生无法忍受和剂量有限的副作用。1因此，新的治疗方法 有必要制定战略，以更好地控制与隐球菌病相关的高死亡率。 尽管疫苗在过去一直被誉为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疫苗的开发 一般情况下，这一直是一个主要障碍，主要是因为对支撑其基础的机制缺乏了解 保护豁免权。此外，真菌疫苗需要在免疫缺陷的情况下有效， 如艾滋病患者的CD4+T细胞淋巴细胞减少症，因为免疫缺陷的患者最多 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(Sgl1)基因，得到的突变体(Δsgl1)是 高度富含甾醇糖苷(SGS)(图3和图4)，否则在野生型CN中检测不到 细胞。SGS是存在于各种真菌和其他微生物中的糖脂，容易刺激 宿主免疫2-4我们发现CNΔsgl1突变体在小鼠模型中不致病(图8A)，并且 鼻腔给药，突变细胞在肺部环境中迅速被杀死(图8B)。非常 有趣的是，接受CNΔsgl1突变体的小鼠在受到毒力CNH99或C.gattii攻击时受到保护。 265个菌株(图10)，这种保护即使在小鼠的CD4+T细胞耗尽时仍然存在(图12)。基座 根据这些观察，我们假设CN Sgl1是真菌毒力的主要调节因子，通过 调节SGS的水平，进而刺激宿主对 隐球菌病。为了验证这一假设，我们提出了以下目标： 目的1.建立Sgl1作为真菌SGS的关键调控因子。在这一目标中，我们将：1)研究 Sgl1的生化特性；以及1B)研究Sgl1在调节SGS和毒力中的作用。 目的2.探讨抗ΔsGL1的宿主免疫机制。在这个目标中，我们将： 导致ΔSGL1清除的免疫反应；2B)检查保护 ΔSGL1免疫的小鼠对二次感染；以及2C)使用耗竭方法检查 细胞对初始清除的要求(2A)和对二次挑战感染的保护(2B)。 这项建议将提供关于真菌SGS调节的作用和机制的第一次见解 一种重要的人类真菌病原菌--CN.它们还可能导致 开发新的抗真菌策略来预防和/和治疗侵袭性真菌感染 具有免疫能力和免疫功能受损的宿主。