Immune Modulation by Bacterial Autolysins

细菌自溶素的免疫调节

• 批准号: 7795786
• 负责人: Laurel L Lenz
• 金额: $ 36.78万
• 依托单位: NATIONAL JEWISH HEALTH
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-04-01 至 2011-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7795786
• 关键词: ARHGEF5 gene; Acute; Address; Affect; Animals; Anti-Bacterial Agents; Anti-Inflammatory Agents; Anti-inflammatory; Antibacterial Response; Applications Grants; Attenuated; Autolysin; Bacillus anthracis; Bacteria; Bacterial Infections; Biochemical; Biological Process; Bioterrorism; Categories; Cell surface; Cells; Cellular Immunity; Chronic; Complement; Cultured Cells; Cytokine Gene; Development; Digestion; Disease; Effectiveness; Elements; Endopeptidases; Engineering; Family; Gene Expression; Generations; Goals; Grant; Growth; Human; IFNAR1 gene; Immune; Immune response; Immunity; Infection; Inflammation; Inflammatory; Inflammatory Response; Interleukin-6; Length; Listeria monocytogenes; Macrophage Activation; Mammalian Cell; Maps; Mediating; Meningitis; Microbe; Modeling; Modification; Molecular; Mus; Natural Immunity; Peptides; Peptidoglycan; Phylogenetic Analysis; Protein Family; Protein Secretion; Proteins; Septicemia; Side; Specificity; Spontaneous abortion; Stimulus; Structure; System; Testing; Therapeutic; Tissues; Vaccination; Vacuole; Virulence; adaptive immunity; antimicrobial; base; cell type; cytokine; cytosolic receptor; immunoregulation; macrophage; microbial; mutant; novel; novel therapeutics; pathogen; pathogenic bacteria; receptor; response; small molecule; sugar; tissue/cell culture; vector vaccine

The SecA2 auxiliary protein secretion system is required for secretion of virulence promoting proteins from a number of Gram-positive pathogens, including Bacillus anthracis (category A) and Listeria monocytogenes (category B). We identified two SecA2-dependent autolytic proteins that promote virulence of L. monocytogenes in infected animals, yet do not affect the growth of this bacterium in tissue culture cells. The virulence of engineered bacterial mutants lacking p60 was restored by expression of full-length p60, but not by expression of a truncated, catalytically inactive protein. The catalytic specificity of p60 predicts that it digests peptidoglycan (PGN) to generate or destroy immune modulating PGN fragments (muropeptides), including respectively muramyl di- and tri-peptides (MDP and MTP). MDP and MTP influence mammalian cell cytokine responses by acting on cytosolic proteins of the Nod family. We have found that p60- expressing bacteria and small molecules released from these bacteria enhance the induction of specific immune-regulatory cytokines by macrophages. In this grant proposal we investigate how p60 promotes virulence and affects host innate immune responses to infection. Our first Aim will identify features of p60 that are required for PGN digestion and for its effects on bacterial virulence and cytokine gene expression. Our second Aim investigates the structure and phylogenetic distribution of a p60-dependent biologically active muropeptide or small molecule and tests whether responses to this molecule require known muropeptide-responsive Nod family proteins. For our third Aim, we investigate a potential mechanism for p60's effects on bacterial virulence by determining how expression of p60 and cytokines induced by p60 affect macrophage responses to activating stimuli. Our studies will define the mechanisms by which this bacterial autolysin contributes to the virulence of a clinically important bacterial pathogen and begin to explore whether similar mechanisms promote virulence of other Gram-positive pathogens, including potential agents of bioterrorism. The mechanisms used by pathogenic bacteria to cause disease include strategies to subvert host immune responses. A subversive strategy that may be common to a number of deadly bacteria is studied in this grant. Our studies will define the molecular basis for this strategy of immune subversion and may thus reveal novel therapeutic avenues to modulate inflammation during bacterial infection, vaccination, and chronic inflammatory diseases.

Seca2辅助蛋白分泌系统是促进蛋白质的毒力分泌所必需的 革兰氏阳性病原体的数量，包括炭疽芽孢杆菌（A类）和单核细胞增生李斯特菌 （B类）。我们确定了两个依赖于L.的Seca2依赖性自溶蛋白。 感染动物中的单核细胞增生，但不会影响该细菌在组织培养细胞中的生长。这 缺乏p60的工程细菌突变体的毒力通过全长p60的表达恢复，但不是 通过表达截短的，催化的无活性蛋白。 p60的催化特异性预测 消化肽聚糖（PGN）生成或破坏免疫调节PGN片段（糊状剂）， 包括分别包括穆拉米基二肽和三肽（MDP和MTP）。 MDP和MTP影响哺乳动物 细胞因子反应通过作用于NOD家族的胞质蛋白。我们发现P60- 从这些细菌释放的细菌和小分子增强了特定的诱导 巨噬细胞的免疫调节细胞因子。在此赠款建议中，我们调查了P60如何促进 毒力并影响宿主对感染的先天免疫反应。我们的第一个目标将确定p60的功能 PGN消化及其对细菌毒力和细胞因子基因表达的影响所必需的。 我们的第二个目标研究了p60依赖性生物学的结构和系统发育分布 活性杂肽或小分子，并测试对该分子的反应是否需要已知 杂肽反应性点头蛋白质。为了我们的第三个目标，我们研究了一种潜在的机制 p60通过确定p60诱导的p60和细胞因子的表达如何对细菌毒力的影响 影响巨噬细胞对激活刺激的反应。我们的研究将定义此机制 细菌自身蛋白酶有助于临床上重要的细菌病原体的毒力 探索类似机制是否促进其他革兰氏阳性病原体的毒力，包括潜力 生物恐怖主义的代理人。 病原细菌引起疾病的机制包括颠覆宿主免疫的策略 回答。在此研究了许多致命细菌可能常见的颠覆性策略 授予。我们的研究将定义这种免疫颠覆策略的分子基础，因此可能 揭示新的治疗途径，以调节细菌感染，疫苗接种和 慢性炎症性疾病。