Mechanisms of Impaired Mycobacteria Sensing by TLR2 and TLR4 Polymorphic Variants

TLR2 和 TLR4 多态性变体损害分枝杆菌感应的机制

• 批准号: 8882763
• 负责人: ANDREI E MEDVEDEV
• 金额: $ 41.27万
• 依托单位: UNIVERSITY OF CONNECTICUT SCH OF MED/DNT
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-07-17 至 2017-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8882763
• 关键词: Address; Affect; Area; Cessation of life; Control Animal; Data; Development; Disease; Drug resistance; Emergency Situation; Engineering; Genetic Polymorphism; Genus Mycobacterium; HIV; Health; Host Defense; Human; Immune; Immune response; Immunity; Incidence; Infection; Inflammation Mediators; Inflammatory; Life; Link; Mediating; Molecular; Multi-Drug Resistance; Mus; Mutation; Mycobacterium Infections; Mycobacterium tuberculosis; National Institute of Allergy and Infectious Disease; Orthologous Gene; Patients; Phagocytosis; Pharmaceutical Preparations; Phosphotransferases; Play; Population; Predisposition; Process; Production; Public Health; Pulmonary Tuberculosis; Receptor Signaling; Regulation; Research; Risk; Role; Severities; Shapes; Single Nucleotide Polymorphism; TLR1 gene; TLR2 gene; TLR4 gene; TLR6 gene; Testing; Therapeutic; Toll-Like Receptor 2; Toll-like receptors; Transgenic Mice; Tuberculosis; Tuberculosis Vaccines; Vaccination; Vaccines; Variant; World Health Organization; base; cytokine; design; global health; improved; in vivo; macrophage; mouse model; mutant; mycobacterial; novel strategies; novel therapeutic intervention; pathogen; prevent; receptor; receptor expression; receptor function; resistant strain; response; sensor; transcription factor; vaccination against tuberculosis

DESCRIPTION (provided by applicant): Mycobacterium tuberculosis (Mtb) infects over one-third of the human population, causing 8 million new cases of pulmonary tuberculosis (TB) each year and ~2.5 million deaths worldwide. The global burden of tuberculosis has been compounded by its deadly association with HIV and by the emergence of multi-drug resistant strains, leading the World Health Organization to declare TB as "a global health emergency". The design of new drugs, vaccines and better therapeutics requires identification of the molecular mechanisms governing immune responses and their regulation upon mycobacterial infection. Toll-like receptors (TLR) 2 and TLR4 are mycobacterial important sensors that play a key role in activating innate host responses, as evidenced by an increased susceptibility to mycobacterial infections and impaired cytokine production in mice deficient for these receptors. In humans, the TLR2 (e.g., R753Q) and TLR4 (e.g., D299G) single nucleotide polymorphisms (SNPs) have been correlated with incidence and/or severity of Mtb infections and TB. However, the molecular mechanisms by which such SNPs affect receptor signaling are unknown. Based on our preliminary data, we formulated the hypothesis that the polymorphisms affect recognition of mycobacteria, TLR signalosome assembly and activation of kinases and transcription factors, altering expression of inflammatory mediators, phagocytosis and predisposing to infection in vivo. This hypothesis will be tested in the following Specific Aims to: 1. Define the impact of the TLR2/4 SNPs on TLR expression, localization, signalosome assembly and activation of key kinases and transcription factors in response to mycobacteria; 2. Determine the effect of the TLR2/4 SNPs on expression of inflammatory mediators, mycobacterial phagocytosis and intracellular survival; and 3. Identify the consequences of TLR2/4 SNPs on susceptibility to mycobacterial infections in vivo in transgenic mice expressing orthologs of human mutations. Our studies are expected to identify mechanisms by which the SNPs affect mycobacterial recognition, TLR2/4 signalosome assembly, activation of kinases and transcription factors, and to link these changes to downstream responses important for host defense against mycobacteria, such as expression of inflammatory cytokines and phagocytosis. We will engineer new transgenic mice expressing orthologs of human R753Q TLR2 or D299G TLR4 SNPs to identify the consequences of these mutations on susceptibility and severity of mycobacterial infections. Elucidation of the molecular basis by which TLR2/4 SNPs compromise host defense against mycobacteria and identification of intermediates with compromised functions will pave the way for the development of new approaches and drugs to improve TLR-mediated Mtb sensing and host defense. These advances would be of key importance for improving public health in tuberculosis patients in the U.S.

描述（申请人提供）：结核分枝杆菌（Mtb）感染超过三分之一的人口，每年造成800万新发肺结核（TB）病例，全球约250万人死亡。结核病与艾滋病毒的致命联系以及多重耐药菌株的出现加剧了结核病的全球负担，导致世界卫生组织宣布结核病为“全球卫生紧急情况”。新药、疫苗和更好的治疗方法的设计需要确定控制免疫反应及其对分支杆菌感染的调节的分子机制。Toll样受体（TLR）2和TLR 4是分枝杆菌的重要传感器，其在激活先天宿主应答中起关键作用，如通过在缺乏这些受体的小鼠中增加的对分枝杆菌感染的易感性和受损的细胞因子产生所证明的。在人类中，TLR 2（例如，R753 Q）和TLR 4（例如，D299 G）单核苷酸多态性（SNP）与Mtb感染和TB的发病率和/或严重程度相关。然而，这些SNP影响受体信号传导的分子机制尚不清楚。基于我们的初步数据，我们提出了这样的假设，即多态性影响分枝杆菌的识别，TLR信号体组装和激酶和转录因子的激活，改变炎症介质的表达，吞噬作用和体内感染的易感性。这一假设将在以下具体目标中进行检验：1.定义的影响 TLR 2/4SNPs对TLR表达、定位、信号体组装以及关键激酶和转录因子的激活的影响; 2.确定TLR 2/4 SNP对炎症介质表达、分枝杆菌吞噬作用和细胞内存活的影响;和3.在表达人类突变直系同源物的转基因小鼠中，确定TLR 2/4 SNP对体内分枝杆菌感染易感性的影响。我们的研究有望确定SNP影响分枝杆菌识别、TLR 2/4信号体组装、激酶和转录因子激活的机制，并将这些变化与宿主防御分枝杆菌的重要下游反应联系起来，如炎症细胞因子的表达和吞噬作用。我们将设计新的转基因小鼠，表达人类R753 Q TLR 2或D299 G TLR 4 SNP的直系同源物，以确定这些突变对分枝杆菌感染的易感性和严重性的影响。阐明TLR 2/4 SNP损害宿主对分枝杆菌防御的分子基础，并鉴定具有受损功能的中间体，将为开发新方法和药物以改善TLR介导的Mtb传感和宿主防御铺平道路。这些进展对于改善美国结核病患者的公共卫生至关重要。