Lipid A & Innate Immune Receptors in Neisseria Infection

脂质A

• 批准号: 8696772
• 负责人: Gary A Jarvis
• 金额: --
• 依托单位: VETERANS AFFAIRS MED CTR SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-04-01 至 2015-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8696772
• 关键词: Acylation; Affinity; Americas; Antibiotic Resistance; Antibiotics; Antibody Formation; B-Lymphocytes; Bacterial Infections; Binding; Biological Assay; CD80 gene; Cell surface; Cells; Cessation of life; Clinical; Clinical Course of Disease; Communities; Complex; Computer Simulation; Contracts; Data; Dendritic Cells; Developed Countries; Development; Disease; Disease Outbreaks; Ectopic Pregnancy; Elements; Enzymes; Epidemic; Epidemiologic Studies; Epithelial Cells; Europe; Genes; Genetic; Goals; Gonorrhea; HIV; HIV-1; Healthcare; Heterogeneity; Human; Immune response; Immune system; Immunologic Receptors; In Vitro; Incidence; Individual; Infection; Infection Control; Infertility; Inflammatory; Inflammatory Response Pathway; Lead; Lipid A; Lipopolysaccharides; MALDI-TOF Mass Spectrometry; Meningitis; Meningococcal Infections; Meningococcal meningitis; Methods; MicroRNAs; Military Personnel; Mission; Modeling; Molecular; Natural Immunity; Neisseria; Neisseria gonorrhoeae; Neisseria meningitidis; Organism; Outcome; Pathogen detection; Pathogenesis; Pathogenicity; Pathway interactions; Patient Care; Patients; Pattern; Pattern recognition receptor; Pelvic Inflammatory Disease; Phosphorylation; Play; Public Health; Relative (related person); Reporting; Research; Role; Sepsis; Septic Shock; Sexually Transmitted Diseases; Signal Transduction; Structure; System; T-Lymphocyte; TNF gene; Testing; Toll-like receptors; Vaccine Design; Vaccines; Variant; Veterans; Virulence; Virulence Factors; Virulent; Woman; Work; base; cell type; chemokine; chronic pain; cytokine; drug development; interferon regulatory factor-3; lipooligosaccharide; monocyte; mutant; neutrophil; novel therapeutics; pathogen; predictive modeling; response; statistics; toll-like receptor 4; transcription factor; transmission process

DESCRIPTION (provided by applicant): Control of Neisseria meningitidis and N. gonorrhoeae infections represents a major public health problem around the world due to increased antibiotic resistance and the lack of vaccines for N. meningitidis serogroup B and N. gonorrhoeae. Our long-term goal is to define molecular determinants of Neisserial pathogenicity to enable development of new therapeutics, to permit rapid assessment of bacterial virulence, to identify patients requiring aggressive treatment, and to facilitate vaccine design. Among the recognized Neisserial virulence factors, lipooligosaccharide (LOS) is a major inducer of the proinflammatory cytokine response to the organisms. Our work and that of others has shown that the lipid A (LA) portion of Neisserial LOS engages innate immune receptor toll-like receptor 4 (TLR4) to initiate a signaling cascade leading to cytokine expression by various cell types such as monocytes, neutrophils, and mucosal epithelial cells. The TLR4 pathway is required for an efficient immune response that protects the host from bacterial infection, but its activation can also induce a proinflammatory state leading to septic shock and death. We have shown that native LOS from different Neisserial strains has variability in both acylation and phosphorylation of LA which is correlated with its potency to induce the same inflammatory cytokines in vitro that are found in patients with meningococcal infection. We also have demonstrated that specific phosphoryl and acyl variants of LA from N. meningitidis strain 89I have differential capacities to induce TNF-1 in human monocytes. We recently confirmed that Neisserial LOS activates both MyD88-dependent and TRIF-dependent pathways through NF-:B and IFN regulatory factor 3 (IRF-3) transcription factors, and to our knowledge, will be the first to report that direct activation of NF-:B is positively correlated with a greater number of phosphoryl substituents. We also have found that MIP-11 and MIP-12 were higher in cells treated with LOS containing LA that had the most phosphoryl substitutions. These data support our overall hypotheses that the inflammatory potential of LA increases with increasing number of phosphoryl substituents, and that variation in the LA structure within the LOS of different Neisserial strains is the major determinant of the degree to which the innate immune system responds to Neisserial infection. Based on the key role of TLR4 in the recognition of LOS, it is apparent that inappropriate signaling of TLR4 by LOS could have important consequences during Neisserial infections, leading to exaggerated responses such as meningococcal sepsis and gonococcal pelvic inflammatory disease. Thus, in the studies proposed herein, we seek to define the LA structural elements that determine inflammatory signaling using genetic deletion and variable expression mutants of meningococcal strain 89I to produce LOS with a single invariant LA moiety that differs in the state of phosphorylation and/or acylation. The Specific Aims are: (1) To determine the molecular mechanisms that regulate the induction of TLR4-dependent innate immune responses to Neisserial LOS in the context of LA structural variation. We will construct genetic variable expression LA mutants and develop a predictive model of LA bioactivity by determining the potential of the mutant LOS to signal through TLR4, to mature dendritic cells and polarize T cells, to induce microRNA, to bind to the TLR4-MD-2 complex, and to induce differences in molecular interactions with TLR4-MD-2 using in silico modeling. (2) To determine the correlation between the predictive model of LA structure and function with the bioactivity and relative abundance of LA expressed by disease-causing and non- pathogenic Neisserial strains. We will correlate the expression by disease-causing and non-pathogenic strains of LA molecules that represent molecular determinants for TLR4 induction with their potential to induce inflammatory cytokines. Our studies are expected to establish the LA structural determinants of inflammatory signaling, to identify new targets for development of antibiotics to treat Neisserial infections, to enable new methods to identify hypervirulent and highly inflammatory strains, and to aid in LOS vaccine design.

描述（由申请人提供）： 由于抗生素耐药性增加以及缺乏针对 B 群脑膜炎奈瑟菌和淋病奈瑟菌的疫苗，控制脑膜炎奈瑟菌和淋病奈瑟菌感染是世界范围内的一个重大公共卫生问题。我们的长期目标是确定奈瑟氏球菌致病性的分子决定因素，以开发新的治疗方法，快速评估细菌毒力，识别需要积极治疗的患者，并促进疫苗设计。在公认的奈瑟氏球菌毒力因子中，脂寡糖（LOS）是生物体促炎细胞因子反应的主要诱导剂。我们和其他人的工作表明，奈瑟氏球菌 LOS 的脂质 A (LA) 部分与先天免疫受体 Toll 样受体 4 (TLR4) 结合，启动信号级联反应，导致各种细胞类型（如单核细胞、中性粒细胞、和粘膜上皮细胞。 TLR4 通路是保护宿主免受细菌感染的有效免疫反应所必需的，但它的激活也会诱发促炎状态，导致感染性休克和死亡。我们已经证明，来自不同奈瑟氏球菌菌株的天然 LOS 在 LA 的酰化和磷酸化方面具有变异性，这与其在体外诱导与脑膜炎球菌感染患者中发现的相同炎症细胞因子的能力相关。我们还证明，来自脑膜炎奈瑟氏球菌菌株 89I 的 LA 的特定磷酰基和酰基变体在人单核细胞中诱导 TNF-1 的能力不同。我们最近证实奈瑟氏菌 LOS 通过 NF-:B 和 IFN 调节因子 3 (IRF-3) 转录因子激活 MyD88 依赖性和 TRIF 依赖性途径，据我们所知，这将是第一个报告直接激活 NF -:B 与较多的磷酰基取代基呈正相关。我们还发现，在用含有最多磷酰基取代的 LA 的 LOS 处理的细胞中，MIP-11 和 MIP-12 较高。这些数据支持我们的总体假设，即 LA 的炎症潜力随着磷酰基取代基数量的增加而增加，并且不同奈瑟氏菌菌株 LOS 内 LA 结构的变化是先天免疫系统对奈瑟氏菌反应程度的主要决定因素感染。基于 TLR4 在 LOS 识别中的关键作用，很明显，LOS 的 TLR4 信号传导不当可能会在奈瑟氏球菌感染期间产生重要后果，导致过度反应，例如脑膜炎球菌败血症和淋菌性盆腔炎。因此，在本文提出的研究中，我们寻求使用脑膜炎球菌菌株89I的基因缺失和可变表达突变体来定义决定炎症信号传导的LA结构元件，以产生具有磷酸化状态不同和/或不同的单个不变LA部分的LOS。酰化。具体目标是： (1) 确定在 LA 结构变异的背景下调节对奈瑟氏菌 LOS 的 TLR4 依赖性先天免疫反应的诱导的分子机制。我们将构建遗传变量表达 LA 突变体，并通过确定突变体 LOS 通过 TLR4 发出信号、成熟树突状细胞和极化 T 细胞、诱导 microRNA、与 TLR4-MD 结合的潜力，开发 LA 生物活性的预测模型2 复合物，并在计算机模型中诱导与 TLR4-MD-2 分子相互作用的差异。 (2)确定LA结构和功能的预测模型与致病和非致病奈瑟氏菌菌株表达的LA的生物活性和相对丰度之间的相关性。我们将把代表 TLR4 诱导的分子决定因素的 LA 分子的致病和非致病菌株的表达与其诱导炎症细胞因子的潜力联系起来。我们的研究预计将建立炎症信号传导的 LA 结构决定因素，确定开发治疗奈瑟氏球菌感染的抗生素的新靶标，启用新方法来识别高毒力和高炎症菌株，并帮助 LOS 疫苗设计。