In situ expression of RANKL, RANK, osteoprotegerin and cytokines in osteoclasts of rat periodontal tissue

本研究检测了RANKL、RANK、OPG、IL-1β和肿瘤坏死因子α在大鼠骨膜组织破骨细胞中的原位表达。选用四周龄Wistar大鼠。采用Waldo法进行牙齿移动，诱导病理性骨吸收。矿化的上颌骨和下颌骨石蜡包埋。采用原位杂交法检测RANKL、RANK。用特异性β探针分别检测破骨细胞和其他细胞中的成骨蛋白、IL-1RNA和肿瘤坏死因子α的表达。RANKL和RANK在一些破骨细胞中同时表达。RANKL在成骨细胞和PDL中也呈阳性表达。未见IL-1β和肿瘤坏死因子α阳性破骨细胞。几乎所有成骨细胞、成牙本质细胞和成牙本质细胞均可检测到护骨素阳性信号。未见骨保护素阳性破骨细胞。当正畸过度用力作用于牙周组织时，RANKL和RANK表达的破骨细胞的数量和分布模式发生了变化。此外，病理状态下破骨细胞表达IL-1β和肿瘤坏死因子α。提示破骨细胞中存在RANKL-RANK的自分泌机制，且在病理条件下RANKL-RANK的自分泌机制增强。此外，病理条件下破骨细胞中IL-1β和肿瘤坏死因子α的自分泌机制也得到了证实。因此，这些自分泌机制似乎在生理和病理条件下调节破骨细胞的功能。

This study examined the in situ expression of RANKL, RANK, OPG, IL-1β and TNFα in the osteoclasts of rat periodohtal tissue. Four-week-old Wistar rats were used. Tooth movement was performed by the Waldo method, and the pathological bone resorption was induced. The mineralized maxillae and mandiblae were embedded with paraffin. In situ hybridization was performed to detect RANKL, RANK. OPG, IL-1β and TNFαmRNA in osteoclasts and other cells using the specific RNA probes, respectively. Both RANKL and RANK were concomitantly expressed in some osteoclasts. RANKL was also positive in osteoblasts and PDLs. No IL-1β and TNFα-positive osteoclast was noted. The positive signals of osteoprotegerin were detected in almost all osteoblasts, PDLs and odontoblasts. No osteoprotegerin-positive osteoclasts were observed. The number and the distribution pattern of RANKL-and RANK-expressing osteoclasts changed when orthodontic excessive force was applied to periodontal tissue. In addition, IL-1β and TNFα were shown to be expressed in osteoclasts under pathological status. These findings suggest that an autocrine mechanism of RANKL-RANK exists in osteoclast, which is heightened in the pathological conditions. Furthermore, the autocrine mechanism of IL-1β and TNFαis also provided in osteoclast under pathological condition. These autocrine mechanisms therefore seem to regulate the osteoclast function in both physiological arid pathological conditions.