C3-Dependent Intracellular Killing in Innate Immunity and Bacterial Pathogenesis

先天免疫和细菌发病机制中 C3 依赖性细胞内杀伤

• 批准号: 10357760
• 负责人: Victor Nizet
• 金额: $ 62.8万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN DIEGO
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-03-05 至 2024-02-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10357760
• 关键词: Affect; Antibiotic Resistance; Autophagocytosis; Bacteremia; Bacteria; Bacterial Infections; Bioinformatics; Blood Circulation; CRISPR screen; Caspase; Cells; Child; Communicable Diseases; Complement; Consequentialism; Coupled; Data; Disease; Elderly; Epithelial; Epithelial Cells; Gene Expression; Genes; Gnotobiotic; Host Defense; Human; Immune; Immunity; Immunocompromised Host; Infection; Infectious Skin Diseases; Investigation; Knowledge; Lead; Libraries; Life; Link; Morbidity - disease rate; Mucosal Immunity; Mucous Membrane; Mus; Natural Immunity; Necrotizing fasciitis; Organ; Outcome; Pathogenesis; Pathogenicity; Pathway interactions; Peptide Hydrolases; Phagocytes; Phagolysosome; Pharmacology; Pharyngitis; Physicians; Play; Process; Production; Proteins; Public Health; Reporting; Research Personnel; Respiratory System; Risk; Role; Salmonella enterica; Scientist; Sepsis; Serine Protease; Serum; Skin; Streptococcal Infections; Streptococcus pyogenes; Surface; System; Tissues; Toxic Shock Syndrome; Vaccines; Virulence; Work; bactericide; commensal microbes; complement system; experience; gut microbiome; human pathogen; in vivo; infection risk; inhibitor; macrophage; microbiome; microbiome composition; mortality; mouse model; mutant; neutrophil; new therapeutic target; novel; pathogen; prevent; skin microbiome; transcriptome sequencing

SUMMARY Bacterial infections remain a leading cause of morbidity and mortality worldwide and a critical public health issue due to increasing antibiotic resistance and limited vaccines. Many of the most consequential bacterial infections originate at mucosal surfaces, such as the gut, respiratory tract or skin, then disseminate to other tissues via the bloodstream. Two preeminent human pathogens causing both mucosal and invasive diseases are Gram- negative Salmonella enterica (e.g., serovar Typhimurium, STm) and Gram-positive group A Streptococcus (GAS). Pivotal to innate host defense against bloodstream infection is the function of complement system proteins and their activation cascades, especially opsonization by C3, coupled with the bactericidal activity of phagocytic cells including macrophages (MΦ) and neutrophils. Pathogenic strains of STm and GAS can subvert phagolysosome function to survive intracellularly in MΦ ex vivo and in vivo, whereupon the autophagy system emerges as a critical battleground for pathogen survival/killing. This project brings together two highly experienced and productive physician-scientist investigators with complementary expertise: Gram-negative bacterial pathogenesis, mucosal immunity and gnotobiotic mouse models (MPI, M. Raffatellu) coupled to Gram- positive bacterial pathogenesis, innate immunity, and bacterial-phagocyte interactions (MPI, V. Nizet). Together we have recently discovered a novel, essential intracellular function of C3: targeting of bacteria to the autophagy system for killing in MΦ – a discovery that may challenge conclusions of countless studies of MΦ-bacterial interactions performed in the absence of active serum. Further, we have discovered that the STm serine protease PgtE, the GAS serine protease SpyCEP, and the GAS cysteine protease SpeB allow the respective pathogens to inactivate C3 and to replicate intracellularly in MΦ. Our central hypothesis is that intracellular C3-dependent autophagy is critical to host innate defense, and that the ability of invasive pathogens such as STm and GAS to counteract this process substantially increases their disease-causing potential. Recent data also indicate the microbiome plays an essential role in skin and mucosal complement production, which may represent another crucial factor by which commensal microbes affect invasive bacterial infection risk. Here we propose to continue to investigate the role of intracellular C3 during infection, to understand the ramifications of this new principle of innate immunity on host-pathogen interactions and the outcome of two of the most important human infectious diseases. Our approaches are likely to reveal new virulence genes and host immune pathways that will connect mechanisms, resolve longstanding knowledge gaps, and lead to new avenues of investigation of broad relevance to bacterial pathogenesis including potential novel therapeutic targets and leads.

概括 细菌感染仍然是全球发病率和死亡率的主要原因，以及关键的公共卫生问题 由于抗生素耐药性增加和疫苗有限。许多最结果的细菌感染 起源于粘膜表面，例如肠道，呼吸道或皮肤，然后通过 血液。两种巨大的人类病原体引起粘膜和侵入性疾病是革兰氏症 肠道阴性沙门氏菌（例如血清鼠伤寒，STM）和革兰氏阳性组A链球菌 （气体）。与先天宿主防御血液感染的关键是完成系统的功能 蛋白质及其激活级联反应，尤其是C3的调子化，再加上细菌活性 吞噬细胞包括巨噬细胞（Mφ）和中性粒细胞。 STM和气体的致病菌株会颠覆 吞噬肌体功能可在Mφex ex Vivo和invivo中细胞内生存，因此自噬系统 成为病原体生存/杀戮的关键战场。这个项目将两个高度汇集在一起 具有完善专业知识的经验丰富且富有成效的身体科学家研究人员：革兰氏阴性 细菌发病机理，粘膜免疫学和gnotobiotic小鼠模型（MPI，M。Raffatellu）与革兰氏阴性 阳性细菌发病机理，先天性免疫和细菌 - 表现细胞相互作用（MPI，V。Nizet）。一起 我们最近发现了C3的新型，必不可少的细胞内功能：将细菌靶向自噬 在Mφ中杀死的系统 - 这一发现可能挑战无数研究的结论 在没有活性血清的情况下进行的相互作用。此外，我们发现STM系列蛋白酶 PGTE，气体丝氨酸蛋白间谍和气体半胱氨酸蛋白SPEB允许相对病原体 使C3失活并在Mφ中细胞内复制。我们的中心假设是细胞内C3依赖性 自噬对于举办先天防御至关重 抵消这一过程大大提高了其引起疾病的潜力。最近的数据还表明 微生物组在皮肤和粘膜完成生产中起着至关重要的作用，这可能代表另一种 共生微生物影响侵入性细菌感染风险的关键因素。在这里我们建议继续 研究细胞内C3在感染过程中的作用，以了解这一新原理的后果 对宿主病原体相互作用的先天免疫力以及两个最重要的人类感染率的结果 疾病。我们的方法可能会揭示新的病毒基因和宿主的免疫途径 机制，解决长期存在的知识差距，并导致广泛发行的新途径 细菌发病机理，包括潜在的新型治疗靶标和铅。