β2 整合素-TLR 膜复合体调控炎症微环境在SE 防治内植物松动的机制研究

We have recently observed that sonodynamic effect (SE) could not only inhibit the formation of bacterial biomembrane on implant, but also promote osteogenesis, and prevent bone resorption and osteolysis around implant induced by polyethylene particles, demonstrating the feasibility and effectiveness of SE in preventing infection and looseness of implant. However, the detailed mechanism of this protective effect remains unclear. In this project， we will systematically analyze the crosstalks among mechanical ultrasound stimulation, signaling proteins on macrophage membrane, and inflammatory microenvironment. Through investigation of the expression, dynamic distribution, and mutual regulation of β2 integrin and TLR transmembrane signaling molecule on the macrophage during ultrasound stimulation, we will elucidate the role of β2 integrin-TLR complex in mechanical ultrasound inhibition of wearing particle-induced inflammation, thereby further clarifying the regulatory mechanisms of mechanical stimulation and inflammatory microenvironment during the process of low frequency ultrasound preventing periprosthetic osteolysis. This project will provide new views and establish theoretical principles for directing the clinical application of low frequency ultrasound appropriately, and formulating personal therapeutic strategy for prevention of periprosthetic osteolysis.

本课题组前期研究发现：超声声动效应（SE）不仅能抑制内植物细菌生物膜的 形成，而且能促进成骨、抑制破骨，遏制聚乙烯颗粒诱导植入体周围骨溶解,证明超声SE 抑 制内植物感染、松动的可行性和有效性。然而，有关SE 抑制内植物松动的确切机制迄今仍 知之甚少。本项目拟系统分析超声力学刺激、巨噬细胞膜信号蛋白、炎症微环境三者间的联 系；观察在超声作用下β2 整合素和TLR 跨膜信号分子在巨噬细胞膜上的表达状况、动态分 布及其相互调控；明确β2 整合素-TLR 复合体在超声力学刺激和磨损颗粒诱导炎症之间的负向调控作用；进一步阐明低频超声防治内植物松动过程中力学刺激和炎症微环境之间的调节机制。本课题将为指导临床上合理运用低频超声和正确制定个性化内植物松动防治方案开拓新的视角并奠定理论基础。

假体周围骨溶解是导致全关节置换翻修的重要原因。假体周围因摩擦、老化产生的磨损颗粒，如钛颗粒、聚乙烯颗粒在骨溶解的发生和进展中发挥重要作用。我们的研究发现，低频超声能显著抑制粒子诱导的假体周围骨溶解，但这种声动效应（SE）的作用机制尚不明确。本项目着重研究发现（1）低频超声能促进粒子诱导的RAW264.7的凋亡，抑制粒子诱导的炎症因子IL-1β , IL-33, IL-6 and IL-8表达，进一步研究发现这种作用通过促进FBXL2基因表达，其表达增加导致TRAP6泛素化增加，有效抑制TRAP6，从而抑制NF-kB信号通路的激活并抑制下游ERK蛋白的磷酸化；（2）低频超声显著抑制RANKL诱导的小鼠原代巨噬细胞和细胞系RAW264.7的破骨分化，但是不影响成熟破骨细胞的骨吸收功能，进一步对信号通路的研究发现，低频超声抑制ERK磷酸化，并通过抑制ERK/c-fos/NFATc1信号轴发挥其抑制作用。上述结果同时获得了体内动物证实。粒子诱导的炎症反应和破骨细胞过度分化是假体松动的主要原因，本项目发现低频超声能显著抑制这两个关键环节，并部分阐明了其机制，为指导临床上合理运用低频超声和正确制定个性化内植物松动防治方案开拓新的视角。