IMMA, Institute of Applied Molecular Medicine, School of Medicine, CEU San Pablo University, Campus Monteprincipe, Boadilla del Monte, 28668, Madrid, Spain.
Centre for Metabolomics and Bioanalysis (CEMBIO), Faculty of Pharmacy, CEU San Pablo University, Campus Monteprincipe, Boadilla del Monte, 28668, Madrid, Spain.
Sci Rep. 2019 Feb 19;9(1):2295. doi: 10.1038/s41598-018-38154-6.
Osteocytes are the main cells of bone tissue and play a crucial role in bone formation and resorption. Recent studies have indicated that Diabetes Mellitus (DM) affects bone mass and potentially causes higher bone fracture risk. Previous work on osteocyte cell cultures has demonstrated that mechanotransduction is impaired after culture under diabetic pre-conditioning with high glucose (HG), specifically osteoclast recruitment and differentiation. The aim of this study was to analyze the extracellular metabolic changes of osteocytes regarding two conditions: pre-conditioning to either basal levels of glucose (B), mannitol (M) or HG cell media, and mechanical stimulation by fluid flow (FF) in contrast to static condition (SC). Secretomes were analyzed using Liquid Chromatography and Capillary Electrophoresis both coupled to Mass Spectrometry (LC-MS and CE-MS, respectively). Results showed the osteocyte profile was very similar under SC, regardless of their pre-conditioning treatment, while, after FF stimulation, secretomes followed different metabolic signatures depending on the pre-conditioning treatment. An important increment of citrate pointed out that osteocytes release citrate outside of the cell to induce osteoblast activation, while HG environment impaired FF effect. This study demonstrates for the first time that osteocytes increase citrate excretion under mechanical stimulation, and that HG environment impaired this effect.
成骨细胞是骨组织的主要细胞，在骨形成和吸收中起着至关重要的作用。最近的研究表明，糖尿病（DM）会影响骨量，并可能导致更高的骨折风险。先前的成骨细胞培养研究表明，在高葡萄糖（HG）的糖尿病预处理条件下培养后，机械转导受损，具体表现为破骨细胞募集和分化受损。本研究旨在分析成骨细胞在两种条件下的细胞外代谢变化：预培养至基础葡萄糖（B）、甘露醇（M）或 HG 细胞培养基，以及与静态条件（SC）相比的流体流动（FF）机械刺激。使用液相色谱和毛细管电泳分别与质谱（LC-MS 和 CE-MS）联用分析分泌组。结果表明，无论预培养处理如何，在 SC 下成骨细胞的特征非常相似，而在 FF 刺激后，分泌组根据预培养处理呈现出不同的代谢特征。柠檬酸的重要增加表明成骨细胞将柠檬酸释放到细胞外以诱导成骨细胞激活，而 HG 环境则损害了 FF 的作用。本研究首次证明成骨细胞在机械刺激下增加柠檬酸排泄，并且 HG 环境损害了这种作用。
