Di Nisio C, Zizzari V L, Zara S, Falconi M, Teti G, Tetè G, Nori A, Zavaglia V, Cataldi A
University of Chieti "G. d'Annunzio".
Eur J Histochem. 2015 Feb 3;59(1):2455. doi: 10.4081/ejh.2015.2455.
Osteonecrosis of the jaw (ONJ) is a chronic complication affecting long-term bisphosphonate-treated subjects, recognized by non-healing exposed bone in the maxillofacial region. The pathophysiological mechanism underlying ONJ has not been fully elucidated. The aim of the present study was to investigate the role of RANK/RANKL/OPG signaling pathway and, in parallel, to evaluate angiogenic and matrix mineralization processes in jaw bone necrotic samples obtained from bisphosphonate-treated subjects with established ONJ. Necrotic bone samples and native bone samples were processed for Light and Field Emission in Lens Scanning Electron Microscope (FEISEM) analyses, for Real-Time RT-PCR to evaluate the gene expression of TNFRSF11A (RANK), TNFSF11 (RANKL), and TNFSF11B (OPG) and for immunohistochemical analyses of VEGF and BSP expression. Morphological analyses performed by Light microscope and FEISEM show empty osteocytic lacunae and alteration of lamellar organization with degradation of the mineralized bone matrix in necrotic bone samples. A significant increase in TNFRSF11A, TNFSF11, TRAF6 and NFAT2 gene expression, and a reduction of TNFSF11B gene transcription level compared is also showed in necrotic bone compared to control samples. No significant difference of VEGF expression is evidenced, while lower BSP expression in necrotic bone compared to healthy samples is found. Even if the pathogenesis of bisphosphonate-associated ONJ remains unknown, a link between oral pathogens and its development seems to exist. We suppose lipopolysaccharide produced by bacteria colonizing and infecting necrotic bone and the surrounding viable area could trigger RANK/RANKL/OPG signaling pathway and, in this context, osteoclasts activation could be considered as a protective strategy carried out by the host bone tissue to delimitate the necrotic area and to counteract infection.
颌骨坏死（ONJ）是长期接受双膦酸盐治疗的患者出现的一种慢性并发症，其特征为颌面部区域暴露骨不愈合。ONJ潜在的病理生理机制尚未完全阐明。本研究的目的是探讨RANK/RANKL/OPG信号通路的作用，同时评估从患有已确诊ONJ的双膦酸盐治疗患者获取的颌骨坏死样本中的血管生成和基质矿化过程。对坏死骨样本和正常骨样本进行处理，用于光学显微镜和场发射透镜扫描电子显微镜（FEISEM）分析、实时逆转录聚合酶链反应（Real-Time RT-PCR）以评估TNFRSF11A（RANK）、TNFSF11（RANKL）和TNFSF11B（OPG）的基因表达，以及VEGF和骨涎蛋白（BSP）表达的免疫组织化学分析。光学显微镜和FEISEM进行的形态学分析显示，坏死骨样本中存在空的骨陷窝，板层结构改变，矿化骨基质降解。与对照样本相比，坏死骨中TNFRSF11A、TNFSF11、TRAF6和NFAT2基因表达也显著增加，而TNFSF11B基因转录水平降低。未发现VEGF表达有显著差异，而与健康样本相比，坏死骨中BSP表达较低。即使双膦酸盐相关ONJ的发病机制仍然未知，但口腔病原体与其发展之间似乎存在联系。我们推测，定植并感染坏死骨及周围存活区域的细菌产生的脂多糖可能触发RANK/RANKL/OPG信号通路，在此背景下，破骨细胞活化可被视为宿主骨组织为界定坏死区域和对抗感染而采取的一种保护策略。
