The impact of hypoxia on Staphylococcus aureus metabolism and virulence during osteomyelitis

骨髓炎期间缺氧对金黄色葡萄球菌代谢和毒力的影响

• 批准号: 9901431
• 负责人: JAMES E CASSAT
• 金额: $ 37.67万
• 依托单位: VANDERBILT UNIVERSITY MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-05-10 至 2022-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9901431
• 关键词: Admission activity; Amino Acids; Anti-Bacterial Agents; Antibiotics; Antimicrobial Resistance; Bacteria; Bone Regeneration; Bone remodeling; Carbon; Cell Death; Cells; Clinical; Cues; Data; Disease; Environment; Functional disorder; Genes; Genus staphylococcus; Glucose; Glycolysis; Growth; Health; Homeostasis; Host Defense; Hypoxia; Hypoxia Inducible Factor; Hypoxia-Inducible Factor Pathway; Immunity; In Vitro; Infection; Invaded; Lactic acid; Life; Maintenance; Measurement; Metabolic; Metabolic Pathway; Metabolism; Modeling; Mus; Musculoskeletal; Nutrient; Open Fractures; Osteitis; Osteoblasts; Osteoclasts; Osteogenesis; Osteomyelitis; Outcome; Oxygen; Pathogenesis; Pathologic; Pathway interactions; Pediatric Hospitals; Penetration; Physiological; Physiology; Production; Proliferating; Property; Pyruvate; Refractory; Resolution; Role; Signal Pathway; Signal Transduction; Skeleton; Source; Staphylococcus aureus; Staphylococcus aureus infection; System; Testing; Therapeutic; Tissues; Toxin; United States; Virulence; Virulence Factors; antimicrobial; bacterial fitness; bacterial metabolism; base; body system; bone; bone turnover; cytotoxicity; flexibility; glucose uptake; human pathogen; microbial; mouse model; mutant; pathogen; programs; quantitative imaging; quorum sensing; response; skeletal; skeletal tissue; success; transposon sequencing

PROJECT SUMMARY / ABSTRACT Staphylococcus aureus is an important human pathogen, capable of causing life-threatening infections in a variety of host tissues. Osteomyelitis, an invasive and debilitating infection of bone, is one of the most common manifestations of staphylococcal disease. Indeed, osteomyelitis accounts for approximately 2-3 of every 1,000 admissions to pediatric hospitals in the United States, and complicates up to 25% of open fractures. Bone infections are notoriously refractory to treatment due to widespread antimicrobial resistance and pathogen-induced bone remodeling, which limits penetration of antibiotics into the infectious focus. S. aureus is by far the most common cause of musculoskeletal infection, yet the mechanisms by which staphylococci survive within and ultimately destroy bone are poorly understood. The overarching objective of this proposal is to understand how S. aureus regulates its virulence and metabolic programs to survive within bone during osteomyelitis. Bone, like most mammalian tissues, is inherently hypoxic. Moreover, maintenance of skeletal health requires constant bone turnover by resident bone-forming osteoblasts and bone-resorbing osteoclasts. These skeletal cells, in turn, require a specialized metabolism characterized by high rates of glucose uptake, which is expected to limit the carbon sources available to invading pathogens. In order to better understand how S. aureus thrives within this hypoxic and metabolically unique environment, we created a powerful murine model of osteomyelitis capable of precise quantification of both bacterial burdens and bone turnover. By applying transposon sequencing (TnSeq) to this osteomyelitis model, we identified >200 staphylococcal genes important for survival in bone. Importantly, bacterial responses to hypoxia were found to be critical determinants of survival during osteomyelitis, as hypoxic growth not only dictates the energy production strategies used by staphylococci, but also augments the production of quorum-dependent virulence factors that participate in bone destruction. Based on these preliminary data, we hypothesize that S. aureus survival in bone is facilitated by (a) quorum-regulated virulence factor expression in response to hypoxia, and (b) specific nutrient utilization programs that enable growth in the unique metabolic environment of bone. The proposed Aims will test this hypothesis to determine (i) the mechanism by which hypoxic growth triggers increased staphylococcal virulence, (ii) the metabolic pathways that support bacterial growth in bone, and (iii) the role of host hypoxic signaling pathways in antibacterial immunity and bone remodeling during osteomyelitis. Completion of these studies will elucidate microbial survival strategies during invasive infection, determine the impact of hypoxia on bacterial pathogenesis, and help to meet a critical need for new osteomyelitis therapeutics by defining putative antimicrobial and anti-virulence targets.

项目概要/摘要 金黄色葡萄球菌是一种重要的人类病原体，能够引起危及生命的感染 在多种宿主组织中。骨髓炎是一种侵袭性、使人衰弱的骨感染，是最常见的疾病之一 葡萄球菌病的常见表现。事实上，骨髓炎约占 2-3 在美国，每 1,000 名儿科医院住院患者中就有 25% 的患者因此而变得复杂化 骨折。由于广泛的抗菌药物耐药性，骨感染很难治疗 病原体引起的骨重塑，限制了抗生素渗透到感染灶中。 S。 金黄色葡萄球菌是迄今为止肌肉骨骼感染最常见的原因，但其机制 人们对葡萄球菌在骨骼中生存并最终破坏骨骼的了解甚少。总体目标 该提案旨在了解金黄色葡萄球菌如何调节其毒力和代谢程序以在其中生存 骨髓炎期间的骨头。 与大多数哺乳动物组织一样，骨骼本质上是缺氧的。此外，维持骨骼健康 需要常驻的骨形成成骨细胞和骨吸收破骨细胞进行持续的骨转换。这些 反过来，骨骼细胞需要一种以高葡萄糖摄取率为特征的特殊代谢，即 预计将限制入侵病原体可用的碳源。为了更好地理解S. 金黄色葡萄球菌在这种缺氧和代谢独特的环境中茁壮成长，我们创建了一个强大的小鼠模型 能够精确量化细菌负荷和骨转换的骨髓炎。通过申请 通过转座子测序 (TnSeq) 对此骨髓炎模型进行分析，我们鉴定出了超过 200 个葡萄球菌基因 对于骨骼的生存很重要。重要的是，细菌对缺氧的反应被发现至关重要 骨髓炎期间生存的决定因素，因为缺氧生长不仅决定能量产生 葡萄球菌使用的策略，但也增加了群体依赖性毒力因子的产生， 参与骨质破坏。根据这些初步数据，我们假设金黄色葡萄球菌在 (a) 缺氧时群体调节的毒力因子表达，以及 (b) 特异性 营养利用计划，使骨骼能够在独特的代谢环境中生长。拟议的 目标将测试这一假设，以确定（i）缺氧生长触发增加的机制 葡萄球菌毒力，(ii) 支持细菌在骨中生长的代谢途径，以及 (iii) 骨髓炎期间抗菌免疫和骨重塑中宿主缺氧信号通路。 这些研究的完成将阐明侵袭性感染期间微生物的生存策略，确定 缺氧对细菌发病机制的影响，有助于满足新骨髓炎的迫切需求 通过定义假定的抗菌和抗毒力目标来进行治疗。