Catalytic Antibodies To Staphylococcus Aureus: Identification and Characterizatio

金黄色葡萄球菌催化抗体：鉴定和表征

• 批准号: 7914338
• 负责人: ERIC L BROWN
• 金额: $ 22.5万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCI CTR HOUSTON
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-14 至 2012-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7914338
• 关键词: Abscess; Adhesions; Anatomic Sites; Anterior; Antibiotic Resistance; Antibiotics; Antibodies; Antigen-Antibody Complex; Antigens; Autoantibodies; Autoimmune Process; B-Lymphocytes; Bacteria; Bacterial Adhesion; Bacterial Infections; Binding; Biological Assay; Blood Circulation; Capsid Proteins; Catabolism; Catalysis; Catalytic Antibodies; Cleaved cell; Clinical; Communities; Community Hospitals; Development; Disease; Dissociation; Endocarditis; Enzymes; Excision; Family; HIV; HIV Envelope Protein gp120; Human; Hydrolysis; Immune; Immune system; Immunoglobulin G; Immunoglobulins; Immunologic Factors; Immunomodulators; Individual; Infection; Infectious Skin Diseases; Maps; Mediating; Microbe; Minor; Minority; Nose; Patients; Peptide Hydrolases; Peptides; Play; Pneumonia; Population; Predisposing Factor; Predisposition; Preparation; Protease Inhibitor; Proteins; Reaction; Recombinants; Reporting; Role; Serum; Site; Skin; Specificity; Staphylococcus aureus; Superantigens; Symptoms; System; Testing; Toxic effect; Toxin; Vestibule; Virulence; Virulence Factors; antigen binding; base; functional loss; human disease; human subject; in vitro Model; in vivo; methicillin resistant Staphylococcus aureus; microbial; microorganism antigen; pathogen; polypeptide; prevent; protective effect; protein function; public health relevance; resistant strain; response; single molecule; treatment strategy

DESCRIPTION (provided by applicant): We propose to test the hypothesis that catabolic antibodies play an important innate defense role in protecting against Staphylococcus aureus infections. S. aureus is an opportunistic pathogen that colonizes the skin (primarily the anterior nasal vestibule) of approximately 20-30% of the population without causing clinical symptoms. If, however, the skin is damaged, S. aureus can gain entry into the host and infections may result in a broad-range of conditions ranging from minor skin complications to lethal infections. Of growing concern are the steadily growing numbers of community-acquired methicillin-resistant S. aureus (CA-MRSA) infections in young, otherwise healthy people. Natural antibodies represent the spontaneous repertoire of circulating immunoglobulins in healthy, unimmunized individuals that form a part of the innate immune system, and they promote the clearance of pathogenic substances from the circulation and prevent pathogen dissemination. Proteolytic antibodies are immunoglobulins endowed with a capacity to catalyze the hydrolysis of polypeptide antigenic substrates, and they hold the potential of specific and efficient catabolism of polypeptides. A single molecule of a catabolic, proteolytic antibody can degrade thousands of antigen molecules. Moreover, the peptide bond cleavage reaction generally results in functional protein inactivation. In comparison, conventional antibodies act stoichiometrically (e.g., IgG binds at most 2 antigen molecules) and the binding is reversible, with the result that active antigen molecules are released upon dissociation of immune complexes. There is growing evidence that microbial antigens can also be targeted by catabolic antibodies. gp120, a coat protein of HIV, is shown to be cleaved by specific proteolytic antibodies that recognize the superantigenic site of gp120 (superantigen, i.e., an antigen recognized by antibodies present in the preimmune repertoire without the requirement for adaptive diversification of the antibody variable domains). To date, a role for catabolic antibodies in defense against bacterial infections has not been examined. In preliminary studies, we observed the cleavage of five important proteins expressed by S. aureus, Efb, protein A, LukF, Map and ClfA by antibody preparations from human subjects. In the present proposal, we will confirm this phenomenon using sera from patients defined by their S. aureus carriage state, characterize the proteolytic specificity and rates, and determine the effects of catalysis on virulence protein function. PUBLIC HEALTH RELEVANCE: S. aureus infections are a growing problem in both community and hospital settings and antibiotic resistant strains have complicated the available treatment strategies. This proposal aims to identify a family of antibodies that also serve as enzymes (catalytic) that cleave virulence factors associated with disease. Identification and characterization of these catalytic antibodies will result in the development of new preventative and treatment strategies against S. aureus infections.

描述（由申请人提供）：我们建议检验分解代谢抗体在预防金黄色葡萄球菌感染方面发挥重要先天防御作用的假设。金黄色葡萄球菌是一种机会性病原体，定植于约 20-30% 人群的皮肤（主要是前鼻前庭），但不会引起临床症状。然而，如果皮肤受损，金黄色葡萄球菌就会进入宿主，感染可能会导致多种疾病，从轻微的皮肤并发症到致命的感染。越来越令人担忧的是，健康的年轻人中社区获得性耐甲氧西林金黄色葡萄球菌 (CA-MRSA) 感染的数量稳步增加。天然抗体代表健康、未免疫个体中循环免疫球蛋白的自发库，构成先天免疫系统的一部分，它们促进循环中致病物质的清除并防止病原体传播。蛋白水解抗体是具有催化多肽抗原底物水解能力的免疫球蛋白，它们具有特异性和有效地分解多肽的潜力。分解代谢蛋白水解抗体的单个分子可以降解数千个抗原分子。此外，肽键裂解反应通常会导致功能性蛋白质失活。相比之下，传统抗体按化学计量起作用（例如，IgG 最多结合 2 个抗原分子），并且这种结合是可逆的，因此在免疫复合物解离时释放出活性抗原分子。越来越多的证据表明微生物抗原也可以成为分解代谢抗体的目标。 gp120 是 HIV 的一种外壳蛋白，显示可被识别 gp120 超抗原位点的特异性蛋白水解抗体切割（超抗原，即被免疫前组库中存在的抗体识别的抗原，而不需要抗体可变域的适应性多样化）。迄今为止，尚未研究分解代谢抗体在防御细菌感染中的作用。在初步研究中，我们观察到人类受试者的抗体制剂对金黄色葡萄球菌、Efb、蛋白 A、LukF、Map 和 ClfA 表达的五种重要蛋白进行裂解。在本提案中，我们将使用由金黄色葡萄球菌携带状态定义的患者血清来确认这种现象，表征蛋白水解特异性和速率，并确定催化对毒力蛋白功能的影响。公共卫生相关性：金黄色葡萄球菌感染在社区和医院环境中都是一个日益严重的问题，抗生素耐药菌株使现有的治疗策略变得复杂。该提案旨在确定一个抗体家族，这些抗体也可作为酶（催化）来裂解与疾病相关的毒力因子。这些催化抗体的鉴定和表征将有助于开发针对金黄色葡萄球菌感染的新预防和治疗策略。