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）： 控制奈瑟氏菌脑膜炎和淋病链球菌感染是由于抗生素耐药性的增加以及脑膜炎链球菌血清群B和N. gonorrhoeae缺乏疫苗，这代表了世界上一个主要的公共卫生问题。我们的长期目标是定义奈瑟氏病致病性的分子决定因素，以使新疗法的发展，允许快速评估细菌毒力，以确定需要积极治疗的患者并促进疫苗设计。在公认的奈瑟尼尔毒力因子中，脂肪糖（LOS）是促炎细胞因子对生物体的主要诱导剂。我们的工作和其他工作表明，脂质A（LA）部分的奈瑟氏菌LOS与先天免疫受体Toll样受体4（TLR4）一起启动信号传导级联反应，从而导致各种细胞类型的细胞因子表达，例如单核细胞，中性粒细胞，中性粒细胞和乳胶上皮细胞。有效的免疫反应需要TLR4途径，以保护宿主免受细菌感染的影响，但其激活也可以诱导促炎状态，导致败血性休克和死亡。我们已经表明，来自不同奈瑟氏菌株的天然LO在LA的酰化和磷酸化方面具有差异，这与其在脑膜炎球菌感染患者中诱导相同的炎症细胞因子的效力相关。我们还证明，脑膜炎链球菌菌株89i的LA的特异性磷酸和酰基变体具有差异能力，可诱导人类单核细胞中的TNF-1。我们最近确认，奈瑟氏菌LOS通过NF-：B：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，将首次报告直接激活NF-：B：B与磷酸化的数量更大的磷酸化代替者的更大相关。我们还发现，用含有最多磷酸化取代的LOS处理的LO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的炎症潜力随磷酸化取代基的数量增加而增加，并且不同奈瑟菌株LOS内LA结构的变化是先天免疫系统对Neiserserial感染反应的程度的主要决定因素。基于TLR4在识别LOS中的关键作用，很明显，LOS对TLR4的不适当信号在奈瑟氏感染期间可能会产生重要的后果，从而导致脑膜炎球菌败血症和肿瘤菌性肿瘤菌造成肿瘤症状的夸张反应。因此，在本文提出的研究中，我们试图定义LA结构元件，这些元素使用遗传缺失和脑膜炎球菌菌株89i的可变表达突变体确定炎症信号传导，以产生具有单个不变的LA部分的LOS，这些LO与磷酸化和/或酰化的状态不同。具体目的是：（1）确定在LA结构变化的背景下，调节TLR4依赖性的先天免疫反应的分子机制。我们将通过确定突变体LOS通过TLR4发出信号，向成熟的树突状细胞和极化T细胞，诱导MicroRNA，与TLR4-MD-2复合物结合并诱导与TLR4-MD-2-2-2-MD-2-MD-2-2-MD-2-MD-2-MD-2-MD-2-MD-2-MD-2的分子相互作用，通过确定突变体LOS通过TLR4发出信号的潜力来构建遗传可变表达LA突变体并开发出LA生物活性的预测模型。 （2）确定LA结构的预测模型与功能与通过疾病引起疾病和非致病性奈瑟菌株表达的LA的生物活性和相对丰度之间的相关性。我们将通过代表TLR4诱导的分子决定因素的LA分子的致病和非致病性菌株与诱导炎性细胞因子的潜力相关联。我们的研究有望建立炎症信号传导的LA结构决定因素，以确定开发抗生素以治疗奈瑟氏感染的新靶标，以使新方法能够鉴定高毒性和高度炎症性菌株，并帮助LOS疫苗疫苗设计。