Interaction Of Pathogenic Bacteria With Human Phagocytic Leukocytes

致病菌与人类吞噬白细胞的相互作用

• 批准号: 7592268
• 负责人: FRANK R DELEO
• 金额: $ 204.08万
• 依托单位: NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7592268
• 关键词: Antibiotic Resistance; Apoptosis; Area; Bacteria; Bacterial Infections; Cells; Communities; Development; Diagnostic; Disease; Epidemic; Gene Proteins; Hospitals; Human; Immune; Immune response; Incidence; Individual; Infection; Inflammation; Invaded; Laboratories; Leukocytes; Lower Respiratory Tract Infection; Modeling; Molecular; Multi-Drug Resistance; New Agents; Nosocomial Infections; Numbers; Pathogenesis; Phagocytosis; Phase; Predisposition; Process; Research; Resolution; Risk Factors; Sepsis; Severities; Skin; Soft Tissue Infections; Staphylococcus aureus; Testing; Time; Tissues; United States; Virulence; base; disorder control; human disease; insight; killings; methicillin resistant Staphylococcus aureus; microbicide; microorganism; neutrophil; pathogen; pathogen exposure; pathogenic bacteria; prophylactic

Human polymorphonuclear leukocytes (PMNs or neutrophils) are essential to the innate immune response against invading microorganisms. In contrast to the acquired immune response, which requires time to develop and is dependent on previous interaction with specific pathogens, the ability of PMNs to kill infectious microorganisms is immediate, non-specific, and not dependent on previous pathogen exposure. Inasmuch as PMNs produce toxic microbicidal components and are the predominant immune cell in most bacterial infections, moderation of infection-induced inflammation is critical for limiting host tissue destruction. Recent evidence suggests PMN apoptosis facilitates resolution of bacterial infections, an idea supported by the finding that pathogens alter neutrophil apoptosis to survive. A key aspect of our research investigates how PMNs ingest and kill bacteria, and elucidates post-phagocytosis sequelae such as apoptosis, processes crucial for the resolution phase of inflammation. These studies established a global model of host cell-pathogen interaction that provides fundamental insight into the resolution of infection in humans. A second focus of research in my laboratory investigates how bacterial pathogens such as Staphylococcus aureus cause human disease. Although most bacteria are killed readily by PMNs, certain strains of S. aureus have evolved mechanisms to circumvent destruction by neutrophils and thereby cause human infections. Notably, S. aureus is the most frequent etiologic agent causing bloodstream infection, skin and soft tissue infection, and lower respiratory tract infection in much of the world, including the United States. In addition, the pathogen has become increasingly resistant to antibiotics over the past few decades and methicillin-resistant S. aureus (MRSA) is a leading cause of hospital-acquired infections. Thus, treatment options are limited. Hospital-acquired MRSA infections are also typical of individuals with predisposing risk factors. In contrast, community-associated (or acquired) MRSA (CA-MRSA) cause disease in otherwise healthy individuals, and these infections can be severe/fatal. There has been an alarming increase in the number of CA-MRSA infections worldwide, which includes an ongoing epidemic of CA-MRSA in the United States. The molecular basis for the increased incidence and severity of CA-MRSA disease is not known. We hypothesize that the ability of bacteria to cause disease is largely due to pathogen-derived factors that alter normal neutrophil function and individual host susceptibility. Therefore, a better understanding of the bacteria-PMN interface at the cell and molecular levels will provide information critical to our understanding, treatment, and control of disease caused by bacterial pathogens. S. aureus is an ideal model pathogen with which to test our hypothesis because it is an important cause of human disease, it can be multi-drug resistant and thus hard to eradicate, and neutrophils are the first line of defense against S. aureus infections. To date, our studies include identification of genes and proteins used by CA-MRSA to evade destruction by human neutrophils, hence contributing to virulence, survival and pathogenesis.

人类多形核白细胞（PMN或中性粒细胞）对于对侵入微生物的先天免疫反应至关重要。与获得的免疫反应相反，获得的免疫反应需要时间来发展并取决于先前与特定病原体的相互作用，PMN杀死传染性微生物的能力是直接的，非特异性的，并且不依赖于先前的病原体暴露。由于PMN会产生有毒的微生物成分，并且在大多数细菌感染中是主要的免疫细胞，因此感染引起的炎症的缓解对于限制宿主组织破坏至关重要。最近的证据表明，PMN的凋亡促进了细菌感染的分辨率，这一发现是由病原体改变中性粒细胞凋亡生存的发现支持的。我们研究的一个关键方面调查了PMN如何摄入和杀死细菌，并阐明了示例性后遗症，例如凋亡，对炎症的分辨率阶段至关重要。 这些研究建立了一种全球宿主细胞原病原相互作用的模型，该模型为人类感染的分辨率提供了基本的见解。 我的实验室研究的第二个焦点调查了金黄色葡萄球菌等细菌病原体如何引起人类疾病。尽管大多数细菌很容易被PMN杀死，但某些金黄色葡萄球菌的菌株已经进化了机制，以绕过中性粒细胞的破坏，从而引起人类感染。值得注意的是，金黄色葡萄球菌是最常见的病因学剂，引起血流感染，皮肤和软组织感染以及包括美国在内的世界上大部分地区的下呼吸道感染。此外，在过去的几十年中，病原体对抗生素越来越抗药性，耐甲氧西林的金黄色葡萄球菌（MRSA）是医院获得性感染的主要原因。因此，治疗方案有限。医院获得的MRSA感染也是具有易感性危险因素的个体的典型特征。相反，与社区相关（或获得）MRSA（CA-MRSA）在其他健康的个体中引起疾病​​，这些感染可能是严重/致命的。全球CA-MRSA感染的数量增加了令人震惊的增加，其中包括美国CA-MRSA的持续流行。尚不清楚CA-MRSA疾病的发病率和严重程度增加的分子基础。 我们假设细菌引起疾病的能力很大程度上是由于病原体衍生的因素改变了正常的中性粒细胞功能和个体宿主的敏感性。因此，对细胞和分子水平的细菌-PMN界面的更好理解将为我们的理解，治疗和控制细菌病原体引起的疾病提供至关重要的信息。金黄色葡萄球菌是一种理想的模型病原体，可以检验我们的假设，因为它是人类疾病的重要原因，它可以具有多药耐药性，因此难以消除，中性粒细胞是针对金黄色葡萄球菌感染的第一道防线。迄今为止，我们的研究包括CA-MRSA使用的基因和蛋白质的鉴定，以避免人类中性粒细胞破坏破坏，从而有助于毒力，生存和发病机理。