金葡假体关节感染（PJI）是关节置换严重并发症，细菌生物膜是致病中心环节。细胞外DNA（eDNA）是体内金葡生物膜的组成要素也是中性白细胞胞外诱捕网（NETs）的重要成分，eDNA的调节是金葡PJI早期生物膜形成关键因素之一。金葡分泌型热核酸酶1降解eDNA促进细菌逃避NETs，却抑制生物膜形成，表现出致病作用矛盾性。金葡膜表面型热核酸酶2具有eDNA调节功能，但其体内致病作用不明。课题组前期研究发现，PJI环境中金葡2种热核酸酶存在反向调节和菌群分工现象，并提出金葡通过2种机制适应PJI环境的假说。本项目在前期工作基础上，构建热核酸酶荧光报告菌株和Tet（on/off）开关质粒，利用金葡-白细胞-假体材料共培养体系及新型生物发光PJI动物模型验证假说的科学性。并拟通过钛基表面氧化纳米管涂层装载二价阳离子释放，干预金葡对PJI环境这种适应性生存机制，为临床防控提供一种崭新的思路和方法。

Staphylococcus aureus associated prosthetic joint infection (PJI) is a devastating complication of arthroplasties, and bacterial biofilm is the key to the pathogenesis of PJI. Extracelluar DNA (eDNA) is an essential component of staphylococcus aureus biofilm in vivo, as well as neutrophil extracellular trap (NET). Regulation of eDNA is one of the elementary factors in the early phase of staphylococcus aureus biofilm formation. The secretory thermonuclease 1(nuc1)of staphylococcus aureus facilitates bacterial escape from NETs by degrading eDNA while simultaneously, hampers biofilm formation in the early phase, playing a paradoxical role in the pathogenesis of PJI. The membrane attached thermonuclease2 (nuc2) of staphylococcus aureus is functional in regulating eDNA while its exact pathogenic role in vivo remains uncovered. In the preliminary studies, our group discovered a “reverse regulation” relationship between nuc1 and nuc2, and a function differentiation phenomenon in bacterial community in the situation of PJI. Therefore, we propose a hypothesis that staphylococcus aureus achieves adaption to PJI environment through two mechanisms. On the basis of preliminary studies, this project plans to construct a thermonuclease fluorescence reporter staphylococcus aureus and a Tet（on/off）plasmid, and use a staphylococcus aureus, neutrophil and implant material co-culture system as well as an in vivo real time quantitative bioluminescence PJI animal model, to verify the scientificity of our hypothesis. In addition, bivalent cations will be loaded into oxidative surface nanotube to intervene the adaptive surviving strategy of staphylococcus aureus in PJI environment, which intends to provide new insight and method for the prophylaxis and treatment of clinical staphylococcus aureus induced PJI.