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Lipid-mediated fungal pathogenesis

脂质介导的真菌发病机制

基本信息

批准号：
10414620
负责人：
Maurizio Del Poeta
金额：
$ 65.99万
依托单位：
STATE UNIVERSITY NEW YORK STONY BROOK
依托单位国家：
美国
项目类别：
财政年份：
2016
资助国家：
美国
起止时间：
2016-07-01 至 2026-08-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10414620
关键词：
Achievement Acquired Immunodeficiency Syndrome Antifungal Agents Antigens Aspergillosis Aspergillus fumigatus Biochemical Biological Assay Blood Circulation Brain CD4 Positive T Lymphocytes CD8-Positive T-Lymphocytes Cells Characteristics Cryptococcosis Cryptococcus neoformans Crystallization Data Defect Development Disease Dose-Limiting Environment Funding Fungal Antigens Fungal Vaccines Genes Glucose Glucuronic Acids Glycolipids Goals Growth HIV Immune response Immunity Immunocompromised Host Immunologic Deficiency Syndromes In Vitro Incubated Infection Intranasal Administration Knowledge Lead Libraries Life Lipids Lung Lymphopenia Mannose Mediating Meningoencephalitis Morbidity - disease rate Mus Mycoses Pathogenesis Pathogenicity Patients Phenotype Polysaccharides Primary Infection Public Health Role Sterols Structure T-Lymphocyte Testing Therapeutic Vaccines Virulence Virulent Xylose base blood glucose regulation capsule fungus glucosidase high throughput screening improved in vitro activity in vivo inhibitor/antagonist insight microorganism mortality mouse model mutant novel pathogenic fungus prevent screening secondary infection side effect small molecule sterol glucoside treatment strategy

项目摘要

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 also 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 (Dsgl1) is highly enriched in sterol glucosides (SGs), which are otherwise not detectable in wild-type (WT) Cn cells.2 SGs are glycolipids present in a variety of fungi and other microorganisms and are prone to stimulate host immunity.3-5 During the previous funding cycle, we showed that Cn Dsgl1 mutant is not pathogenic in a mouse model and, upon intranasal administration, the mutant cells are rapidly eliminated in the lung environment.2 Very interestingly, mice receiving Cn Dsgl1 mutant are now protected when challenged with virulent Cn WT and this protection is achieved even when mice are CD4+ or CD8+ T cell depleted, mimicking the HIV+ host (Fig.12 and2). We validated the role of Sgl1 in second fungal pathogen, Aspergillus fumigatus (Af). The Af DsglA is also not virulent (Fig. 9) and able to protect against a secondary Af WT infection (Fig. 11). Importantly, we initiated a high throughput screening and found small molecules that inhibit Sgl1 or SglA activity in vitro, accumulates SGs in fungal cells (Fig. 6), exert in vitro antifungal activity against Cn and Af in minimum media with low glucose concentrations (Figs. 2 and 3), and block the dissemination of Cn to the brain (Fig. 5), mimicking the phenotypes observed with the respective Dsgl1 or DsglA mutants. In addition, a key characteristic of Cn is its polysaccharide capsule, mainly made of glucuronic acid, xylose and mannose (GXM). Very interestingly, we found that deletion of GXM totally abrogates the protective phenotype of Cn Dsgl1.6 In fact, the administration of the Cn Dcap59/Dsgl1 double mutant does not protect against a secondary infection (Fig. 8). Based on these observations, we hypothesize that Cn Sgl1 is a major regulator of fungal virulence by modulating the level of SGs, which, through GXM, stimulate the host immune response against cryptococcosis (Fig. 1). To test this hypothesis, we propose the following aims: Aim 1. To determine the role of Cn Sgl1 and Af SglA on fungal virulence. Aim 2. To study the host immune response against Cn accumulating SGs. This proposal will provide novel insights on the role and mechanisms by which fungal SGs regulate the pathobiology in Cn. Importantly, these studies will also potentially lead to the development of novel antifungal strategies to prevent and/or treat invasive fungal infections, such as cryptococcosis and aspergillosis, in immunocompromised hosts.

摘要