热休克蛋白HSP90-Notch信号通路在巨噬细胞诱导的骨形成过程中的作用机制

Heterotopic ossification occurs when the body suffered severe stress factors. It is similar to normal bone tissue in terms of both histological structure and physiological metabolism, which suggests that the osteogenic mechanism of heterotopic ossification can be used to guide bone formation. The applicant previously found that the levels of early macrophages and mesenchymal stem cells in the ectopic ossification area were significantly increased. In addition, high expression of HSP90 was observed in macrophages in both heat-shock stimulated locations and heterotopic ossified areas. However, in vitro thermal stimulation has no significant osteoblastic induction effect. It was reported that HSP90 can stabilize the Notch signaling pathway by interacting with the intracellular active structure ICN1 of Notch receptor, which suggested that HSP90 from macrophage might participate in osteogenesis process via Notch signaling. This project intends to establish an in vivo and in vitro heat shock induced heterotopic ossification model to explore the role of macrophage HSP90 in promoting osteogenic differentiation, its interaction with Notch signaling pathway and its mechanism in regulating osteogenesis. Finally, verify the osteoinduction ability of HSP90 in bone defect models. This project will investigate the mechanism of HSP90 in macrophage-induced heterotopic ossification from multiple perspectives in vitro and in vivo, providing a theoretical basis for solving the problem of periodontitis induced peri-implants bone defect.

机体受到严重刺激后发生的异位骨化从组织学到生理变化上都与正常骨组织类似。这提示我们可利用异位骨化的产生机制来指导骨重建。申请人前期发现体内异位骨化区早期巨噬细胞和间充质干细胞水平显著升高，且体内外热刺激后巨噬细胞高表达热休克蛋白HSP90，而体外短暂热刺激并不能直接诱导成骨细胞分化。已有研究表明HSP90可与Notch受体的胞内活性结构ICN1相互作用，激活Notch信号通路，而Notch信号通路又广泛参与了骨代谢过程，申请人推测巨噬细胞HSP90可能通过Notch信号通路调控成骨过程。本项目拟通过构建体内外热刺激诱导异位骨化模型，研究巨噬细胞HSP90在促进成骨中的作用及其对Notch信号通路的影响和调控成骨细胞的机制，并通过骨缺损模型的构建验证其诱导骨再生的能力。本项目通过体内外实验多角度研究巨噬细胞HSP90诱导成骨的具体机制，为解决牙周炎造成的种植体周围骨量不足问题提供理论基础。

异位骨化过程从组织学到生理变化上都与正常骨组织形成类似。这提示我们可利用异位骨化的产生机制来指导骨重建。免疫细胞参与并调控生物材料引起的异位成骨作用，而且具体作用机制尚不完全清楚。本项目通过构建异位成骨模型，首先研究了不同生物材料引起的免疫反应与骨再生的作用，发现巨噬细胞介导的非特异性免疫和树突状细胞介导的特异性免疫参与介导生物材料诱导成骨过程中的作用及时机不同。其中，具有骨诱导性能的生物材料在植入后早期激活巨噬细胞M2型极化，在中晚期抑制树突状细胞成熟，从而促进成骨。基于这一发现，我们开发出双波段控释纳米系统，分别在植入材料后的先天免疫阶段和适应性免疫阶段，分别释放白介素4和地塞米松，调控巨噬细胞极化、抑制树突状细胞成熟，减少对T细胞的免疫激活，精准调控生物材料植入后的免疫反应，为材料成骨构建理想的炎症微环境，显著提升了现有材料的骨再生效果。本研究结果证明了免疫系统多细胞共同参与并决定了生物材料诱导的骨再生效果；提示了免疫细胞反应作为生物材料评价体系的有效性，证明了调控免疫反应、塑造成骨免疫微环境在骨再生策略中的重要性。本研究还从微观尺度研究和发现了不同特性的生物材料对蛋白质的吸附作用不同，从而激发不同的免疫反应，选择和设计合适尺度和特性的生物材料有助于开发具有更优免疫调控能力的骨再生材料。