Complementary Mechanisms of Protection Against Pneumococcal Infection

预防肺炎球菌感染的补充机制

基本信息

批准号：
9913982
负责人：
Edward N Janoff
金额：
--
依托单位：
VA EASTERN COLORADO HEALTH CARE SYSTEM
依托单位国家：
美国
项目类别：
财政年份：
2019
资助国家：
美国
起止时间：
2019-04-01 至 2023-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9913982
关键词：
Address Adherence Agglutination Alveolar Macrophages Antibodies Bacteremia Bacteria Bacterial Pneumonia Binding Binding Sites Blood Circulation Cell Line Cessation of life Cleaved cell Clinical Data Cryoelectron Microscopy Enzymes Epithelial Epithelial Cells Epithelial Receptor Cell Epithelium Epitope Mapping Epitopes Failure Frequencies Genetic Genetic Variation Geography Human IgA-specific serine endopeptidase IgA1 Immune Sera Immune response Immunize Immunoglobulin A Immunoglobulin Constant Region Immunoglobulin G Immunoglobulin Variable Region In Vitro Infection Inhalation Invaded Investigation Lung Mediating Molecular Molecular Conformation Morbidity - disease rate Mucous Membrane Mus Nose Organism Patients Peptide Hydrolases Peptide Mapping Peptides Phagocytes Phagocytosis Pneumococcal Infections Pneumococcal Pneumonia Pneumonia Polysaccharides Prevention Proteins Residual state Respiratory Mucosa Respiratory System Risk Role Sepsis Serotyping Serum Specificity Streptococcus pneumoniae Structure-Activity Relationship Surface Surface Antigens Upper Respiratory Infections Vaccination Vaccines Veterans Virulence Factors Work capsule disorder prevention in vivo mortality mouse model mucosal site murine monoclonal antibody neutralizing antibody neutralizing monoclonal antibodies neutrophil novel novel vaccines pathogen patient subsets pneumococcal surface protein A pre-clinical prevent protease C respiratory response success vaccine candidate

项目摘要

A leading cause of pneumonia and related morbidity and mortality is the mucosal pathogen, Streptococcus pneumoniae. Beginning at the upper respiratory mucosa, infection begins with colonization which can then be complicated by pneumonia and invasive bloodstream infections. The most prominent antibody in these mucosal sites is the IgA1 subclass. IgA1 antibodies to the pneumococcal capsule, its primary virulence factor, are generated in response to colonization, symptomatic infection and vaccination. The variable region of IgA1 binds to the organism and the constant region binds to phagocytes (e.g., alveolar macrophages and neutrophils). A pneumococcal enzyme, IgA1 protease, is expressed on the surface of the bacteria. IgA1 bound to the capsule is cleaved by the protease at the bridging hinge between the variable and constant region, thereby inhibiting the ability of IgA1 to support phagocytosis, killing and clearance of the organism. Residual variable regions that remain on the surface modify the bacteria's surface and enhance binding to epithelial cell receptors, likely promoting colonization with the organism. This subversion of the protective host response to S. pneumoniae predisposes older veterans to increased risk for serious infection. Preventing the bacteria's inactivation of the host's response can be achieved by a subset of patients with invasive pneumococcal disease who generate IgG in serum that neutralizes the protease's ability to cleave IgA. Moreover, we have generated murine monoclonal antibodies (mMabs) that bind and some neutralize the protease. We propose to advance our understanding of the structure-function relationships of the protease and consider the feasibility of advancing this protein as a primary or adjunctive vaccine candidate. In this context, we Hypothesize that: 1) Neutralizing antibodies to IgA1 protease recognize conserved epitopes on the enzyme. 2) Protease-neutralizing antibodies with human IgA1 and prevent epithelial cell binding in vitro and colonization with intranasal challenge in vivo by inhibition of IgA1 cleavage. 3) Antibodies to IgA1 protease protect mice against fatal mucosal infection with S. pneumoniae indirectly by inhibiting cleavage of human IgA1 bound to the bacterial surface and directly by surface binding and mediating phagocytosis of the organism. To address these Hypotheses, we propose to pursue the following Specific Aims: Aim 1. Characterize the epitopes targeted by protease-neutralizing monoclonal antibodies (Mabs) and their genetic conservation. Aim 2. Characterize the epitopes targeted by protease-neutralizing monoclonal antibodies (Mabs) and their genetic conservation. Aim 3. Determine the ability of protease-specific Mab's to protect against fatal infection after mucosal challenge in vivo and the mechanisms underlying protection. This work is directed to determine the targets of the protease-neutralizing antibodies, the geographic and molecular diversity of pneumococcal proteases to consider the generalizability of these investigations, and the ability of protease binding and neutralization on IgA1 effector functions to prevent colonization and to support phagocytosis and killing of S. pneumoniae both in vitro and in vivo in mouse models. These studies provide important basic and pre-clinical data for considering the role of the protease in vaccine disease prevention and, potentially, therapy.

肺炎及相关发病率和死亡率的主要原因是粘膜病原体链球菌肺炎杆菌。从上呼吸道粘膜开始，感染开始于定植，然后可以被并发肺炎和侵袭性血流感染。这些抗体中最突出的粘膜部位是 IgA1 亚类。肺炎球菌荚膜的 IgA1 抗体，其主要毒力因子，是由于定植、症状感染和疫苗接种而产生的。 IgA1可变区与生物体结合，恒定区与吞噬细胞（例如，肺泡巨噬细胞和中性粒细胞）。肺炎球菌酶 IgA1 蛋白酶在细菌表面表达。 IgA1 结合胶囊在可变区和恒定区之间的桥接铰链处被蛋白酶切割，从而抑制 IgA1 支持生物体吞噬、杀伤和清除的能力。残差保留在表面的可变区域改变细菌的表面并增强与上皮细胞的结合受体，可能促进生物体的定植。这颠覆了宿主的保护反应肺炎链球菌使老年退伍军人容易受到严重感染的风险增加。部分患者可以防止细菌对宿主反应的失活。侵袭性肺炎球菌疾病，在血清中产生 IgG，中和蛋白酶的裂解能力免疫球蛋白A。此外，我们还制备了鼠单克隆抗体 (mMab)，可以结合并中和蛋白酶。我们建议加深对蛋白酶结构与功能关系的理解并考虑将该蛋白作为主要或辅助候选疫苗的可行性。在这个上下文中，我们假设： 1) IgA1 蛋白酶的中和抗体识别酶上的保守表位。 2) 蛋白酶中和抗体与人 IgA1 并防止上皮细胞结合体外和体内鼻内攻击通过抑制 IgA1 裂解进行定植。 3) IgA1蛋白酶抗体通过间接保护小鼠免受肺炎链球菌的致命粘膜感染抑制与细菌表面结合的人类 IgA1 的裂解，并直接通过表面结合和介导生物体的吞噬作用。为了解决这些假设，我们建议追求以下具体目标：目标 1. 表征蛋白酶中和单克隆抗体 (Mab) 靶向的表位及其遗传保护。目标 2. 表征蛋白酶中和单克隆抗体 (Mab) 靶向的表位及其遗传保护。目标 3. 确定蛋白酶特异性单克隆抗体在粘膜感染后防止致命感染的能力体内挑战和潜在的保护机制。这项工作旨在确定蛋白酶中和抗体的靶标、地理和肺炎球菌蛋白酶的分子多样性，以考虑这些研究的普遍性，以及蛋白酶结合和中和 IgA1 效应子功能的能力，以防止定植并支持在小鼠模型中体外和体内吞噬和杀死肺炎链球菌。这些研究提供考虑蛋白酶在疫苗疾病预防中的作用的重要基础和临床前数据，潜在的，治疗。