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、跨学科的方法。这通常包括密集的、长期的系统抗生素治疗和外科清创，同时增加局部抗生素的使用，目的是克服这些威胁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，克服日益严重的金黄色葡萄球菌骨科感染问题，需要清楚地了解导致这些感染的发展、成熟、持久性和治疗顽固性的细菌毒力因素，以及这些因素对宿主骨细胞生理的影响。我们的结果表明，在这方面的一个关键因素是葡萄球菌辅助调节因子(SARA)和SAESRS调节系统相对于彼此的功能状态。具体地说，我们已经确定，这些基因座相对于彼此的功能状态可以用来定义血源性骨髓炎的“毒力梯度”，它是由特定毒力因子的产生和它们的蛋白酶介导的降解之间的平衡所定义的，前者主要由saeRs的功能状态调节，后者主要由sARA的功能状态调节。在这项建议中，我们将使用在当代临床分离的USA300克隆谱系(LAC)中产生的突变，在急性血源性骨髓炎、手术后急性原位骨髓炎和慢性骨髓炎的经过验证的动物模型中充分验证这一假说。这将使我们能够识别特定的毒力因子，其丰度以与体内定义的毒力梯度一致的方式变化，从而使我们能够识别并优先考虑可能在骨髓炎所有阶段发挥重要作用的金黄色葡萄球菌毒力因子。 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的机制基础。总的来说，拟议研究的完成将为开发可用于预防和治疗金黄色葡萄球菌骨科感染的新策略奠定基础。

 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.