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: 9765616
• 负责人: Victor Nizet
• 金额: $ 62.93万
• 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/9765616
• 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 Cells; Epithelium; 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/antagonist; 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，也是一个重要的公共卫生问题 由于抗生素耐药性增加和疫苗有限。许多最严重的细菌感染 起源于粘膜表面，如肠道、呼吸道或皮肤，然后通过 血流。引起粘膜疾病和侵袭性疾病的两种重要的人类病原体是革兰氏阴性菌。 阴性肠道沙门氏菌（例如鼠伤寒血清型，STm）和革兰氏阳性 A 组链球菌 （气体）。补体系统的功能是宿主抵抗血流感染的先天防御的关键 蛋白质及其激活级联，特别是 C3 的调理作用，以及杀菌活性 吞噬细胞包括巨噬细胞（MΦ）和中性粒细胞。 STm 和 GAS 的致病菌株可以破坏 吞噬溶酶体在 MΦ 离体和体内的细胞内存活，因此自噬系统 成为病原体生存/杀死的关键战场。该项目汇集了两个高度 经验丰富、富有成效的医师科学家研究人员，具有互补的专业知识：革兰氏阴性菌 细菌发病机制、粘膜免疫和 gnotobiotic 小鼠模型 (MPI, M. Raffatellu) 与 Gram- 阳性细菌发病机制、先天免疫和细菌吞噬细胞相互作用（MPI，V. Nizet）。一起 我们最近发现了 C3 的一种新颖的、重要的细胞内功能：将细菌靶向自噬 MΦ 杀灭系统——这一发现可能挑战无数 MΦ 细菌研究的结论 在没有活性血清的情况下进行相互作用。此外，我们还发现 STm 丝氨酸蛋白酶 PgtE、GAS 丝氨酸蛋白酶 SpyCEP 和 GAS 半胱氨酸蛋白酶 SpeB 允许各自的病原体 使 C3 失活并在 MΦ 中进行细胞内复制。我们的中心假设是细胞内 C3 依赖性 自噬对于宿主先天防御至关重要，并且 STm 和 GAS 等侵入性病原体的能力 抵消这一过程会大大增加其致病潜力。最新数据还表明 微生物组在皮肤和粘膜补体的产生中发挥着重要作用，这可能代表了另一个 共生微生物影响侵袭性细菌感染风险的关键因素。在此我们建议继续 研究细胞内 C3 在感染过程中的作用，了解这一新原理的影响 先天免疫对宿主-病原体相互作用的影响以及两种最重要的人类传染病的结果 疾病。我们的方法可能会揭示新的毒力基因和宿主免疫途径，这些途径将连接 机制，解决长期存在的知识差距，并带来具有广泛相关性的新调查途径 细菌发病机制，包括潜在的新治疗靶点和线索。