巨噬细胞氧化应激在糖尿病致“钛-骨”界面失稳中的作用和机制研究

Titanium-based materials have become the most widely used metal implants in clinics nowadays. However, the immediate and long-term implant stability is not satisfied with high rates of implant loosening or failure under pathological conditions. It has been reported that diabetic patients encounter a much higher failure rate of titanium implantation (15-30%) than that of 1-3% for the general non-diabetic population. Several studies showed that the foreign body response occurred at bone-implant interface may significantly impact short- and long-term tissue responses with implanted devices. But the underlying mechanism still remains elusive. Our previous research showed that implantation under pathological conditions may contribute to the generation of inflammatory response and reactive oxygen species (ROS), which adversely affected the osteoblast biological functions at the bone-implant interface. It indicated the vital role of the interactions between macrophage-mediated inflammatory response and ROS, which may negatively influenced interface stability collectively. Based on these data, the present research attempt to gain a mechanistic understanding of the effect of the pivot “macrophage—ROS” axis on instability at titanium-abnormal bone mineralization interface as well as the molecular regulatory network in the process. The source, coupling and development of the axis at the bone-implant surface would be focus on, specially its effect on the interactions between bone metabolism and vascularization. Furthermore, we will investigate new bio-functional titanium implant that could control the macrophage polarization. All these researches are expected to enrich our knowledge of the pathogenesis about implant failure under pathological conditions as well as provide theoretical and experimental basis for therapeutic strategies in clinical treatment.

松动是糖尿病患者应用钛金属植入物最常见和最严重的并发症，发生率高达15%-30%。而糖尿病诱发的“钛－骨”界面失稳是植入物松动最重要的内源性因素，但具体机制尚不清楚。结合文献和我们的研究发现：ROS爆发介导的氧化应激引起骨生长和血管化的破坏，是糖尿病致界面失稳的关键因素；而界面巨噬细胞（MΦ）的极化状态可能是ROS的作用位点和效应机制。我们的研究旨在通过探讨糖尿病诱发MΦ内氧化应激的作用机理，明确细胞微环境中ROS爆发对MΦ极化状态的调节效应，阐明MΦ极化异常在“钛—骨”界面失稳中的作用地位，着重关注“ROS爆发--MΦ极化异常”这一调控机制对钛植入物表面“骨长入/血管长入”平衡进程的影响，并在此基础上提出MΦ极化可控的功能性钛植入物的研发思路。本研究的实施将深入揭示糖尿病致钛金属植入物松动的关键发病机制，对植入物表面改性以提高界面稳定性、降低植入物松动率具有重大的理论和临床意义。

医用钛合金材料凭借其良好的机械性能以及可靠的生物相容性已广泛应用于人体骨骼修复与重建。流行病学研究发现，糖尿病患者钛合金植入物失败率高达15-30%，而 “钛-骨”界面强度是维持植入物稳定的关键性因素。有研究证实在糖尿病条件下巨噬细胞M1/M2极化平衡被打破，而这种失衡状态可能影响了骨长入或血管长入，导致钛植入物松动，但目前尚无相关研究报道。.本课题在国家自然科学基金的资助下，主要针对上述问题取得如下进展：..1. 发现巨噬细胞极化异常是糖尿病致骨植入物易松动的重要机制。成功建立体外“钛-骨”界面模型，关注于巨噬细胞在糖尿病条件下对“钛-骨”界面成骨细胞功能的影响，证明糖尿病促进巨噬细胞向M1极化并抑制向M2极化，损伤成骨细胞功能，经IL-4处理后，促进了巨噬细胞由M1向M2极化，进而促进成骨细胞功能。由此证明了巨噬细胞在糖尿病致骨植入物松动问题中的作用。.2. 发现西他列汀可改善糖尿病致“钛-骨”界面成骨细胞失稳的作用。西他列汀作为一种DPP-4 抑制剂，不仅能够增加骨骼强度，也具有减轻炎症的作用。在明确巨噬细胞极化异常在糖尿病致“钛-骨”界面成骨细胞功能失稳中的关键地位的基础上，我们进一步观察西他列汀在糖尿病致“钛-骨”界面上成骨细胞功能失稳中的作用及机制，阐明1 μg/ml浓度下西他列汀可明显改善糖尿病导致成骨细胞功能受损的情况。.3. 针对“钛-骨”界面巨噬细胞极化设计了“西他列汀/蚕丝蛋白”支架用于改善糖尿病致钛植入物失稳。通过体内外实验，证实蚕丝蛋白具备良好的生物相容性及可靠的降解性能，同时能够作为缓释媒介释放西他列汀，提高界面骨整合能力。..本研究利用蚕丝蛋白作为载药媒介，局部缓释西他列汀，可明显调节糖尿病条件下巨噬细胞失稳状态，并显著改善骨整合能力，效果优于口服西他列汀处理，为临床上改善糖尿病致钛植入物失稳提供重要的实验依据。