Impact of Staphylococcus aureus in osteomyelitis and bone physiology

 描述（由申请人提供）：骨髓炎是一种破坏性的骨感染，其治疗需要复杂的跨学科方法。这通常涉及强化的、长期的全身性抗生素治疗和手术清创，伴随着额外的局部抗生素递送，旨在克服这些危及生命的感染的内在耐药性，同时避免全身毒性。骨髓炎和其他形式的骨科感染的主要原因是金黄色葡萄球菌。我们的假设是，克服S。金黄色葡萄球菌骨科感染将需要清楚地了解有助于这些感染的发展、成熟、持续和治疗耐受性的细菌毒力因子，以及这些因子对宿主骨细胞生理学的影响。我们的研究结果表明，在这方面的一个关键因素是葡萄球菌辅助调节（sarA）和saeRS监管系统相对于彼此的功能状态。具体来说，我们已经建立了这些位点相对于彼此的功能状态，可以用来定义一个“毒力梯度”在血行性骨髓炎，这是由特定的毒力因子的生产和它们的蛋白酶介导的降解之间的平衡定义，前者介导的功能状态主要由saeRS和后者介导的功能状态主要由sarA。在本提案中，我们将使用USA300克隆谱系（LAC）的当代临床分离株中产生的突变体，这些突变体在这两个调控位点的功能状态上不同，以在急性血源性骨髓炎、急性手术后原位骨髓炎和慢性骨髓炎的经验证动物模型中充分询问这一假设。这将使我们能够确定特定的毒力因子，其丰度以与体内定义的毒力梯度一致的方式变化，从而使我们能够确定和优先考虑S。金黄色葡萄球菌毒力因子可能在骨髓炎的所有阶段发挥重要作用 疾病过程。然后，我们将确定这些毒力因子在体内的作用，并研究这些毒力因子影响宿主骨细胞生理学的机制基础。总的来说，完成拟议的研究将为开发可用于预防和治疗S的新策略奠定基础。金黄色骨科感染。

 DESCRIPTION (provided by applicant): Osteomyelitis is a devastating bone infection, the treatment of which requires a complicated, interdisciplinary approach. This most often involves intensive, long-term systemic antibiotic therapy and surgical debridement accompanied by additional local antibiotic delivery aimed at overcoming the intrinsic resistance of these life- threatening infections while avoiding systemic toxicity. The leading cause of osteomyelitis and other forms of orthopaedic infection is Staphylococcus aureus. Our hypothesis is that overcoming the growing problem of S. aureus orthopaedic infections will require a clear understanding of the bacterial virulence factors that contribute to the development, maturation, persistence, and therapeutic recalcitrance of these infections, as well as the impact these factors have on host bone cell physiology. Our results demonstrate that a key element in this regard is the functional status of the staphylococcal accessory regulator (sarA) and the saeRS regulatory system relative to each other. Specifically, we have established that the functional status of these loci relative to each other can be used to define a "virulence gradient" in hematogenous osteomyelitis that is defined by the balance between the production of specific virulence factors and their protease-mediated degradation, with the former mediated primarily by the functional status of saeRS and the latter mediated primarily by the functional status of sarA. In this proposal, we will use mutants generated in a contemporary clinical isolate of the USA300 clonal lineage (LAC) that differ in the functional status of these two regulatory loci to fully interrogate this hypothesis in validated animal models of acute hematogenous osteomyelitis, acute post-surgical orthotopic osteomyelitis, and chronic osteomyelitis. This will position us to identify specific virulence factors whose abundance varies in a manner consistent with the virulence gradient defined in vivo, thereby allowing us to identify and prioritize the S. aureus virulence factors that are likely to play important roles in all stages of the osteomyelitis disease process. We will then determine the role of these virulence factors in vivo and investigate the mechanistic basis by which these virulence factors impact host bone cell physiology. Collectively, completion of the proposed studies will set the stage for the development of novel strategies that can be used for the prevention and treatment of S. aureus orthopaedic infections.