Role of the Staphylococcus aureus SaeR/S Regulatory System in Neutrophil Evasion

金黄色葡萄球菌 SaeR/S 调节系统在中性粒细胞逃逸中的作用

• 批准号: 8186276
• 负责人: Jovanka M Voyich
• 金额: $ 33.54万
• 依托单位: MONTANA STATE UNIVERSITY - BOZEMAN
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-07-01 至 2016-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8186276
• 关键词: Address; Antibiotics; Attenuated; Bacterial Infections; Binding; Biological Assay; Cessation of life; Communities; Complex; Consensus Sequence; Cytolysis; Cytoplasmic Granules; Data; Disease; Effectiveness; Environment; Exposure to; Gene Components; Gene Targeting; Genes; Goals; Hospitals; Human; Immune response; Incidence; Individual; Infection; Infectious Skin Diseases; Integration Host Factors; Kinetics; Knowledge; Lead; Life; Methicillin Resistance; Methods; Molecular; Morbidity - disease rate; Natural Immunity; Pathogenesis; Phagocytosis; Phenotype; Plasmids; Pneumonia; Positioning Attribute; Prevention strategy; Public Health; Publishing; Reactive Oxygen Species; Recombinants; Regulation; Regulator Genes; Research; Role; Septicemia; Severity of illness; Signal Transduction; Staphylococcal Infections; Staphylococcus aureus; System; Testing; Transcript; Transcriptional Regulation; United States; Virulence; Virulence Factors; base; clinically relevant; direct application; extracellular; human disease; human morbidity; human mortality; improved; in vivo; insight; killings; methicillin resistant Staphylococcus aureus; mortality; mouse model; mutant; neutrophil; novel; pathogen; promoter; resistant strain; response; skin abscess; treatment strategy

DESCRIPTION (provided by applicant): Staphylococcus aureus (S. aureus) is a leading cause of human infections worldwide, resulting in a diverse spectrum of disease severity from mild to life-threatening. Recently, there has been an increase in the incidence of community-associated methicillin-resistant S. aureus (CA-MRSA) infections in otherwise healthy individuals, the basis of which is largely unknown. Human polymorphonuclear leukocytes (PMNs or neutrophils) are the first line of defense against bacterial infections. The ability of S. aureus to circumvent destruction by innate immunity includes survival after PMN phagocytosis. The ability of S. aureus to survive following PMN phagocytosis is dependent on the pathogen's ability to sense and survive the hostile PMN environment. However, specific mechanisms used by S. aureus to evade PMN killing are incompletely defined. We hypothesize that the SaeR/S two-component regulatory system directly regulates S. aureus factors that impair an effective neutrophil response resulting in pathogen survival. This hypothesis is based on the following published and preliminary observations: 1) saeR and saeS transcripts were up-regulated following PMN phagocytosis; 2) deletion of saeR/S significantly decreased survival of S. aureus following human PMN phagocytosis; and 3) transcriptional assays identified extracellular virulence genes down- regulated in saeR/S and direct binding of recombinant SaeR to a consensus sequence within several of these virulence gene promoters. These data correlate well with in vivo studies that demonstrate SaeR/S regulates factors vital for S. aureus - induced morbidity following skin infections and mortality following invasive infections. To determine the molecular mechanisms behind the saeR/S-dependent phenotype we will first define the kinetics of activation of SaeR/S-regulated genes in response to PMN phagocytosis. Next, we will determine the contribution of individual SaeR/S-target genes to S. aureus survival and PMN lysis. Finally, we will assess expression of saeR/S-target genes in vivo and identify the contribution of individual genes regulated by saeR/S to S. aureus pathogenesis. Completion of this research will identify the specific effectors regulated by saeR/S responsible for survival following PMN phagocytosis and will define their contribution to PMN lysis and S. aureus pathogenesis in vivo. These findings will improve our understanding of the initial host-pathogen interactions that lead to S. aureus infection. This knowledge is predicted to have direct application for novel prevention and treatment strategies for staphylococcal infections. PUBLIC HEALTH RELEVANCE: Staphylcoccus aureus (S. aureus) is a leading cause of morbidity and mortality worldwide. The emergence of hyper-infectious community-associated methicillin resistant (CA-MRSA) strains within the community is a major public health concern. Given the diminishing effectiveness of our current antibiotics, it is clear we must improve our understanding of molecular mechanisms fundamental to S. aureus pathogenesis in order to develop better methods to control/treat S. aureus disease and thus improve public health.

描述（由申请人提供）：金黄色葡萄球菌（S. aureus）是全世界人类感染的主要原因，导致多种疾病严重程度，从轻微到危及生命。最近，健康个体中社区相关的耐甲氧西林金黄色葡萄球菌 (CA-MRSA) 感染的发病率有所增加，但其基础尚不清楚。人类多形核白细胞（PMN 或中性粒细胞）是抵抗细菌感染的第一道防线。金黄色葡萄球菌通过先天免疫规避破坏的能力包括中性粒细胞吞噬后的存活。金黄色葡萄球菌在中性粒细胞吞噬作用后存活的能力取决于病原体感知和在恶劣的中性粒细胞环境中生存的能力。然而，金黄色葡萄球菌逃避中性粒细胞杀灭的具体机制尚未完全确定。我们假设 SaeR/S 双组分调节系统直接调节金黄色葡萄球菌因子，这些因子会损害有效的中性粒细胞反应，从而导致病原体存活。该假设基于以下已发表的初步观察结果：1）saeR 和 saeS 转录本在 PMN 吞噬作用后上调； 2) saeR/S的缺失显着降低了金黄色葡萄球菌在人PMN吞噬后的存活率； 3)转录测定鉴定了saeR/S中下调的细胞外毒力基因，并且重组SaeR直接结合到这些毒力基因启动子中的几个内的共有序列。这些数据与体内研究很好地相关，这些研究证明 SaeR/S 调节对金黄色葡萄球菌至关重要的因素——皮肤感染后引起的发病率和侵袭性感染后的死亡率。为了确定 saeR/S 依赖性表型背后的分子机制，我们首先定义 SaeR/S 调节基因响应 PMN 吞噬作用的激活动力学。接下来，我们将确定各个 SaeR/S 靶基因对金黄色葡萄球菌存活和 PMN 裂解的贡献。最后，我们将评估 saeR/S 靶基因的体内表达，并确定受 saeR/S 调节的单个基因对金黄色葡萄球菌发病机制的贡献。这项研究的完成将确定由 saeR/S 调节的负责 PMN 吞噬后存活的特定效应器，并将确定它们对 PMN 裂解和体内金黄色葡萄球菌发病机制的贡献。这些发现将提高我们对导致金黄色葡萄球菌感染的最初宿主-病原体相互作用的理解。预计这一知识将直接应用于葡萄球菌感染的新型预防和治疗策略。 公共卫生相关性：金黄色葡萄球菌（S. aureus）是全世界发病和死亡的主要原因。社区内高度传染性的社区相关耐甲氧西林 (CA-MRSA) 菌株的出现是一个主要的公共卫生问题。鉴于目前抗生素的有效性逐渐减弱，显然我们必须提高对金黄色葡萄球菌发病机制的基本分子机制的理解，以便开发更好的方法来控制/治疗金黄色葡萄球菌疾病，从而改善公众健康。