骨质疏松中“铁蓄积”对破骨细胞功能改变的分子机制研究

The existing related studies and our researches showed: "Iron accumulation" might be a independent risk factor causing the occurrence of osteoporosis. Meanwhile, a great deal of researches showed that iron accumulation could inhibit osteoblast function, which was closely associated with some signal pathways like Wnt pathway. However, relationship between osteoclasts and iron accumulation, especially its molecular mechanism remained unclear. Osteoporosis involved in abnormal bone formation and resorption. Taken into account that postmenopausal osteoporosis was a high bone turnover state, studies of osteoclasts’ molecular mechanism seemed to be more meaningful. Therefore, we thought that the study of the relationship between "Iron accumulation" and osteoclasts was a key point in completely understanding the relationship of "iron accumulation" and osteoporosis. In addition, this study was also a basic information in future clinical applications of reducing iron accumulation..Our pre-experiment had been observed: Iron accumulation really conducted the impact on Bone Marrow derived Macrophages(BMMs) differentiation (stimulating osteoclasts differentiation). Therefore,the objective of this project was listed below:.1.BMMs derived from postmenopausal patients suffering from osteoporotic fractures were extracted from bone marrow and cultured; Serum was collected for cell culture. .2.Menopausal rats (OVX model)were interved with Ferric ammonium citrate (FAC) for iron accumulation rat models. BMMs and serum were extracted. Cells were cultured with autologous serum of rats and carried out with iron reduction interventions..3.Related indicators of MAPK, NF-kB, Calcineurin/NFATc1 signaling pathway and Vacuolar H+—ATPase were detected. Briefly speaking, osteoclasts derived from rat bilateral tibia were cultured and then with the treatments of DFO, a iron chelating drug. Same indicators were measured..Detection: Osteoclasts differentiation index of stem cell (TRAP staining), osteoclasts activity indicators (Bone pits resorption test). Results of iron metabolism (Ferritin), bone metabolism (β-CTX, Trap-5b), MAPK, NF-kB, Calcineurin/NFATc1 signaling pathway targets and related gene or protein expression of Vacuolar H+—ATPase (ATP6V1a1, TCIRG1)..Analysis: Impacts of "iron accumulation" and "iron reduction" on osteoclasts, and the relationship between these effects and bone resorption or MAPK, NF-kB, Calcineurin/NFATc1 signaling pathway and Vacuolar H+—ATPase. Aim to put forward a hypothesis:"iron accumulation" affected the relationship between osteoclasts and bone resorption, which were associated with one or more molecular mechanism. "Iron reduction" was a possible preventive measure, which might enrich the philosophy of osteoporosis prevention and treatment.

近年研究提出“铁蓄积”是绝经后骨质疏松症一个“独立危险因素”；铁蓄积与成骨细胞“机制”研究有许多，但铁蓄积与破骨细胞“机制”缺少报道；然而破骨细胞在骨质疏松发生中地位重要，所以研究“铁蓄积影响破骨细胞功能的分子机制”非常必要。.破骨细胞骨吸收分子机制有许多，经典的是与“分化”相关的MAPK、NF-κB、NFATC1通路，与“活性”相关的质子泵功能；预实验提示铁蓄积与上述通路部分相关，故本项目计划：运用“铁蓄积骨松大鼠”和“骨松骨折患者”的骨髓悬液行破骨细胞培养，以自体血清干预（模拟体内铁蓄积环境）；细胞层面观察“分化和活性”相关通路改变，大体层面观察“铁代谢和骨代谢”相关指标变化；反向实验采用降铁药物干预；“动物组”获得典型指标提供“人体组”验证。获全部结果后，分析“铁蓄积”“降铁药物”与细胞实验指标间相互逻辑关联，阐述破骨细胞功能改变的分子机制，为骨质疏松症防治新方法提供研究数据。

大量临床及基础研究提出“铁蓄积”是绝经后骨质疏松症一个“独立危险因素”；目前铁蓄积与破骨细胞“机制”缺少研究。本项目主要研究内容包括：研究“铁蓄积”对鼠源性破骨细胞活性及分化的影响；研究“铁蓄积”对人源性破骨细胞活性及分化的影响；研究“DFO(降铁方法)”干预后“破骨细胞”的通路蛋白变化。我们的实验结果表明：铁蓄积小鼠的原代破骨细胞存在明显的NF-kB及MAPK信号通路激活，铁可能通过激活NF-kB通路，进一步促进骨吸收。在收集的高龄女性骨髓组织中发现血清铁蛋白/骨铁与骨密度存在负相关性。根据本项目实验结果，NF-kB可能是铁影响破骨细胞活性的重要通路，通过抑制该通路，可部分恢复骨量，因此，针对该通路的临床转化有一定的应用前景，也为骨质疏松症防治新方法提供研究数据。

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