Peansukmanee Siriporn, Vaughan-Thomas Anne, Carter Stuart D, Clegg Peter D, Taylor Sarah, Redmond Colette, Mobasheri Ali
Faculty of Veterinary Science, University of Liverpool, Merseyside, United Kingdom.
J Orthop Res. 2009 Apr;27(4):529-35. doi: 10.1002/jor.20772.
Articular chondrocytes exist in an environment lacking in oxygen and nutrients due to the avascular nature of cartilage. The main source of metabolic energy is glucose, which is taken up by glucose transporters (GLUTs). In diseased joints, oxygen tensions and glucose availability alter as a result of inflammation and changes in vascularisation. Accordingly, in this study we examined the effects of hypoxia and the hypoxia mimetic cobalt chloride (CoCl(2)) on glucose transport in equine chondrocytes and compared expression of the hypoxia responsive GLUT1 gene in normal and diseased cartilage. Monolayers of equine chondrocytes were exposed to 20% O(2), 1% O(2), CoCl(2) (75 microM), or a combination of 1% O(2) and CoCl(2). Glucose uptake was measured using 2-deoxy-D-[2,6-(3)H] glucose. GLUT1 protein and mRNA expression were determined by FACS analysis and qPCR, respectively. GLUT1 mRNA expression in normal and diseased cartilage was analyzed using explants derived from normal, OA, and OCD cartilage. Chondrocytes under hypoxic conditions exhibited a significantly increased glucose uptake as well as upregulated GLUT1 protein expression. GLUT1 mRNA expression significantly increased in combined hypoxia-CoCl(2) treatment. Analysis of clinical samples indicated a significant reduction in GLUT1 mRNA in OA samples. In OCD samples GLUT1 expression also decreased but did not reach statistical significance. The increase in glucose uptake and GLUT1 expression under hypoxic conditions confirms that hypoxia alters the metabolic requirements of chondrocytes. The altered GLUT1 mRNA expression in diseased cartilage with significance in OA suggests that reduced GLUT1 may contribute to the failure of OA cartilage repair.
由于软骨无血管的特性，关节软骨细胞存在于缺氧和缺乏营养物质的环境中。代谢能量的主要来源是葡萄糖，它通过葡萄糖转运蛋白（GLUTs）被摄取。在患病关节中，由于炎症和血管化变化，氧张力和葡萄糖可用性会发生改变。因此，在本研究中，我们检测了缺氧和缺氧模拟物氯化钴（CoCl₂）对马软骨细胞葡萄糖转运的影响，并比较了正常和患病软骨中缺氧反应性GLUT1基因的表达。将马软骨细胞单层暴露于20% O₂、1% O₂、CoCl₂（75 μM）或1% O₂与CoCl₂的组合中。使用2-脱氧-D-[2,6-(³)H]葡萄糖测量葡萄糖摄取。分别通过流式细胞术分析和定量PCR测定GLUT1蛋白和mRNA表达。使用来自正常、骨关节炎（OA）和骨软骨损伤（OCD）软骨的外植体分析正常和患病软骨中GLUT1 mRNA的表达。缺氧条件下的软骨细胞表现出葡萄糖摄取显著增加以及GLUT1蛋白表达上调。在缺氧 - CoCl₂联合处理中，GLUT1 mRNA表达显著增加。临床样本分析表明，OA样本中GLUT1 mRNA显著降低。在OCD样本中，GLUT1表达也降低，但未达到统计学意义。缺氧条件下葡萄糖摄取和GLUT1表达的增加证实缺氧改变了软骨细胞的代谢需求。OA中患病软骨中GLUT1 mRNA表达的改变具有显著性，这表明GLUT1减少可能导致OA软骨修复失败。
