GLP-1抑制AGEs-RAGE信号通路防治糖尿病性骨质疏松的研究

Diabetes-associated osteoporosis is prevalent and adversely affects the health of the elderly because of its high morbidity and great risk of fracture. It is certain that advanced glycation end products(AGEs) play a central role in the pathogenesis of diabetes-associated osteoporosis by inhibiting osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) and degradating osteogenic microenvironment. Our preliminary study in vitro has confirmed that GLP-1 promoted BMSCs'proliferation , osteogenic differentiation, and inhibited apoptosis through suppressing expression of RAGE(receptor for advanced glycation end products) protein and mRNA levels in BMSCs and endothelial cell. In vivo we have proved that GLP-1 improved the deficient bone formation and bone structure in type 2 diabetes mellitus animal model. In view of above evidences, we hypothesize that GLP-1 could be in the involvement in osteogenesis through increasing BMSCs' differentiation into osteoblasts and improving osteogenic microenvironment by blocking AGEs-RAGE system. This program aims at investigation of the inhibition effect of GLP-1 on AGEs in proliferation and osteogenic differentiation of BMSCs and osteogenesis microenvironment using rat bone marrow-derived BMSCs, fetal mouse metatarsal and spontaneous type 2 diabetic animal model OLETF rats, and simultaneously explore the possibilities of signaling pathway in vivo and in vitro. The clarification of the above issues will provide a new theoretical basis and drug target for the prevention and therapy of diabetes-associated osteoporosis.

糖尿病性骨质疏松发病率高、易致骨折,严重威胁老年人的健康。糖基化终产物（AGEs）抑制骨髓间充质干细胞（BMSCs）向成骨细胞分化，并恶化成骨微环境，是致病的主要原因之一。项目组前期研究发现，胰高血糖素样肽-1 (GLP-1)可下调BMSCs和血管内皮细胞中AGEs受体表达，促进细胞增殖、抑制凋亡，并上调BMSCs成骨分化指标；在体实验中，GLP-1也能改善糖尿病动物骨质量。据此，我们推测GLP-1可通过抑制糖尿病人BMSCs和骨髓微血管内皮细胞的AGEs-RAGE途径，改善成骨分化及成骨微环境，促进骨形成。本项目在此基础上，以BMSCs、胎鼠趾骨血管、自发性糖尿病大鼠为研究对象，分别从细胞-组织-整体三个层面研究GLP-1对AGEs作用下的MSCs增殖、凋亡、成骨细胞分化及骨髓成骨微环境等方面的影响及具体信号通路。阐明上述问题将为改善糖尿病性骨质疏松临床防治提供新的理论依据和新药靶。

中国人群糖尿病（DM）发病率高达11.6%，糖尿病性骨质疏松引发的骨折是众多DM患者严重的健康问题。目前发现降血糖药物胰高血糖素样肽-1（GLP-1）可改善糖尿病状态下的骨形成，但具体作用机制尚未阐明，项目组推测其与抑制晚期糖基化产物（AGEs）所致氧化应激有关。本课题从细胞和整体水平围绕GLP-1对糖尿病状态下成骨代谢、骨质量及AGEs-RAGE-氧化应激信号进行系统研究，得出如下结果：1、小鼠长骨来源成骨细胞（OB）膜上存在功能性GLP-1受体（GLP-1R）的表达，GLP-1通过GLP-1R促进OB的增殖与成骨分化。2、氧化产物AOPP和AGEs通过与受体RAGE结合，升高细胞活性氧（ROS）水平，呈剂量、时间依赖性抑制间充质干细胞（MSCs）及OBS增殖、成骨分化；GLP-1可通过下调AGEs诱导的RAGE表达，减少ROS产生，即GLP-1可通过抑制AGEs-RAGE-氧化应激的信号达到促骨形成的作用。3、在小剂量STZ腹腔注射诱导的高脂2型糖尿病大鼠模型中，给予GLP-1受体激动剂艾塞那肽和DPP-4酶抑制剂沙格列汀后，大鼠前肢骨低骨量状况得以明显改善，其机制考虑与GLP-1促进OB功能、抑制破骨细胞功能，并改善生长板活性、促进骨生长率、改变糖尿病造成的低骨转换状态有关。4、在自发型2型糖尿病大鼠ZDF模型中，GLP-1受体激动剂利拉鲁肽具有控制血糖、降低体重、改善内环境紊乱、减少AGEs的形成、降低氧化应激、上调骨形成指标、降低骨吸收指标、改善骨质的作用。以上结果从多个层面揭示GLP-1降糖作用外改善骨代谢的效应及具体机制，为糖尿病性骨质疏松的临床防治提供新的理论依据和新药靶。目前发表SCI论文3篇，中文核心期刊7篇。