应用组学技术构建颅脑损伤促进骨折愈合的分子调控网络

Scientific evidence suggests the association between traumatic brain injury (TBI) and enhanced osteogenesis. Clinical and observational studies have shown that fractured long bones heal more quickly and make more calluses in TBI patients than in those without TBI. An increased incidence was seen of heterotopic ossification (HO), rapid bone union, and early bone union with hypertrophic callus formation, in those with significant TBI. However, the potential molecular mechanism for this phenomenon remains unknown. There is a hypothesis that bone formation is regulated by serum factors which leak from brain into blood due to blood–brain barrier (BBB) dysfunction, or may result from the systemic response to TBI. In our previous studies, we confirmed that the increased molecules (Haptoglobin, Interleukin-6 and Arachidonic acid) in serum after TBI may play a key role in enhancing the speed of fracture healing (For details, see the progress of the studies.). These findings may provide evidence for future research on the association between TBI and fracture healing. Based on the above work, this project aims to investigate further molecular expression profiling in TBI rat serum by "omics" approaches, to establish the database of differential molecules, and to explore the associations between differential molecules and events. Moreover, molecular regulatory network for promoting fracture healing during traumatic brain injury was constructed with bioinformatic analysis combined with further functional study. The novel findings may provide useful information to understand the molecular mechanisms and novel insights into the association between TBI and fracture healing, and to identify the potential drug targets for fracture treatment in clinics.

临床实践证据显示颅脑损伤合并骨折的患者比单纯骨折患者的骨折愈合快、骨痂生长快且数量多，预示颅脑损伤可能会促进骨折愈合。虽然大量的证据显示颅脑损伤与异位骨化、快速的骨连接和肥大骨痂密切相关，但其潜在的分子机制仍不明确。有假说认为，颅脑损伤后可能由于血脑屏障的破坏或机体的系统反应造成血液内一些分子浓度改变，这些分子进一步调节了患肢骨折的愈合。我们通过前期研究证实在颅脑损伤后血液中一些分子（如触珠蛋白、白介素6和花生四烯酸）显著上调，并且它们可能在骨折愈合过程中扮演着重要的调控作用（详见研究进展）。本项目旨在前期工作基础上，利用最新的组学技术，完善颅脑损伤血清中生物活性分子表达谱研究，建立颅脑损伤后血清中的差异分子库，探究差异分子与颅脑损伤促进骨折愈合的关系，构建颅脑损伤促进骨折愈合的分子调控网络，初步探讨其潜在的分子机制以及论证个别差异分子作为潜在药物靶点的可能。

临床实践中观察到颅脑损伤合并骨折的患者比单纯骨折患者的骨折愈合快、骨痂生长快且数量多，预示颅脑损伤可能促进骨折愈合。大量科学证据显示颅脑损伤与异位骨化、快速的骨连接和肥大骨痂密切相关，也提出多种学术假说，但其分子机制仍不明确。骨折愈合速度主要取决于炎症期、软骨痂和硬骨痂形成期，而骨折修复的机械强度则主要与骨重建期合成和分解的平衡有关。我们前期研究表明颅脑损伤合并骨折大鼠患肢骨折位点骨密度和矿化程度高、骨小梁大、成骨细胞多且胞浆丰富，且颅脑损伤动物血清能够促进成骨细胞MC3T3-E1 增殖和BGLAP 的表达，证实血液循环系统可能在颅脑损伤促进骨折愈合过程中扮演核心关联角色，从而在骨折愈合早期调控骨生成。本项目利用多种生命组学技术，系统地开展颅脑损伤大鼠血清/浆生物活性分子表达谱研究，建立颅脑损伤后血清/浆差异分子库，共筛选到116个生物活性分子发生显著变化，其中差异蛋白39个，差异代谢物8个，差异循环小RNA（miRNAs）69个；结合生物信息学分析，针对性开展Hp、AA和miR-183-5p等差异分子的生物功能研究，Hp通过参与血肿炎症期调控骨折愈合速度，AA通过促进成骨细胞增殖和BGLAP的表达加速成骨细胞的成熟，进而调控软骨痂和硬骨痂的形成，miR183-5p可能通过靶向Egr1调控骨生成和代谢过程；挖掘整合多组学数据，构建分子调控网络，明确分子间相互作用类型和关系，寻找调控网络中关键的Hub蛋白分子。项目从局部解析相关分子参与调控骨生成过程，到整体认识颅脑损伤促进骨折愈合的分子机制，为开展临床样本验证和转化研究提供理论依据。阐释颅脑损伤促进骨折愈合机制的同时，为骨质疏松症和骨折的预防和干预提供新的思路，对我国老龄化加剧带来的骨质疏松症患病率上升提前做好准备具有一定的实际意义。