Chen Shuo, Zhang Lei, Xu Ruonan, Ti Yunfan, Zhao Yunlong, Zhou Liwu, Zhao Jianning
1 Department of Orthopedics, Jinling Hospital, Nanjing University School of Medicine, Nanjing 210002, China.
2 Offices of Health Care, Jinling Hospital, Nanjing University School of Medicine, Nanjing 210002, China.
Exp Biol Med (Maywood). 2017 Feb;242(4):422-428. doi: 10.1177/1535370215625471. Epub 2016 Jul 24.
The bradykinin B2 receptor (BDKRB2) plays a key role in the inflammation process of osteoarthritis. Nitric oxide has also long been considered to be a catabolic factor that contributes to inflammatory response and the osteoarthritis disease pathology. Several studies have reported that the BDKRB2 +9/-9 bp polymorphisms are associated with transcription of the receptor. However, the roles of BDKRB2 polymorphisms in inflammation in osteoarthritis remain unclear. This study enrolled 156 subjects with primary knee osteoarthritis and 58 healthy volunteers. BDKRB2 polymorphisms were genotyped, and the mRNA and protein levels of BDKRB2 in synovial tissues from osteoarthritis patients were measured by quantitative real-time polymerase chain reaction and western blot analysis, respectively. Nitric oxide production in serum from patients with osteoarthritis was measured using a nitric oxide assay kit. We found that the mean BDKRB2 mRNA levels were significantly higher in Kallgren-Lawrence grade-4 osteoarthritis patients than patients with lower grade osteoarthritis. The +9/-9 bp polymorphisms significantly affected the BDKRB2 mRNA and protein expression levels in synovial tissues from osteoarthritis subjects. Osteoarthritis patients with +9/-9 and -9/-9 genotypes had higher BDKRB2 expression levels in synovial tissue and nitric oxide production in serum. Moreover, positive correlation was found between the BDKRB2 levels in synovial tissue and nitric oxide production. Compared with health controls, significant increases of nitric oxide production in osteoarthritis were detected which were associated with increasing severity of osteoarthritis. Multiple linear regression analysis (adjusted for gender and age) showed serum nitric oxide level was positively associated with BDKRB2 polymorphism and Kallgren-Lawrence grade and was inversely associated with obesity. Our findings showed that the BDKRB2 +9/-9 bp polymorphisms affected the gene expression and nitric oxide production, which were associated with radiographic severity of osteoarthritis, suggesting that the BDKRB2 +9/ -9 bp polymorphisms may act as a genetic modulator of osteoarthritis, and play an essential role in inflammatory process in osteoarthritis.
缓激肽B2受体（BDKRB2）在骨关节炎的炎症过程中起关键作用。长期以来，一氧化氮也被认为是一种分解代谢因子，可促进炎症反应和骨关节炎疾病病理过程。多项研究报道，BDKRB2 +9/-9 bp多态性与该受体的转录有关。然而，BDKRB2多态性在骨关节炎炎症中的作用仍不清楚。本研究纳入了156例原发性膝关节骨关节炎患者和58名健康志愿者。对BDKRB2多态性进行基因分型，并分别通过定量实时聚合酶链反应和蛋白质印迹分析测定骨关节炎患者滑膜组织中BDKRB2的mRNA和蛋白质水平。使用一氧化氮检测试剂盒测量骨关节炎患者血清中的一氧化氮生成量。我们发现，卡尔格伦-劳伦斯4级骨关节炎患者的BDKRB2 mRNA平均水平显著高于低级别骨关节炎患者。+9/-9 bp多态性显著影响骨关节炎患者滑膜组织中BDKRB2的mRNA和蛋白质表达水平。携带+9/-9和-9/-9基因型的骨关节炎患者滑膜组织中BDKRB2表达水平较高，血清中一氧化氮生成量也较高。此外，滑膜组织中BDKRB2水平与一氧化氮生成之间存在正相关。与健康对照相比，骨关节炎患者的一氧化氮生成量显著增加，且与骨关节炎严重程度增加相关。多元线性回归分析（校正性别和年龄）显示，血清一氧化氮水平与BDKRB2多态性和卡尔格伦-劳伦斯分级呈正相关，与肥胖呈负相关。我们的研究结果表明，BDKRB2 +9/-9 bp多态性影响基因表达和一氧化氮生成，这与骨关节炎的影像学严重程度相关，提示BDKRB2 +9/-9 bp多态性可能作为骨关节炎的遗传调节因子，在骨关节炎的炎症过程中起重要作用。
