ラット一過性アンキローシスモデルにおけるRANKL、RANKおよびOPGの定性的検討

A qualitative investigation of RANKL, RANK and OPG in a rat model of transient ankylosis.

• Linda Curl
• Chien Wei Tan
• Craig W Dreyer
• Wayne Sampson

抄録

はじめに:

これまでの研究では、ラットモデルで開始された無菌性根吸収の炎症過程の一部としてアンキローシスが生じることが明らかになっている。このような樹状歯槽膿漏の発生と治癒反応の生理的メカニズムについては、未だに不明な点が多い。核内因子-κβリガンド（RANKL）、核内因子-κβリガンド（RANK）、オステオプロテゲリン（OPG）などの受容体活性化因子が吸収の理解に勢いを増しているが、歯槽膿漏症におけるこれらの役割については、これまでの研究では明らかにされていない。

INTRODUCTION: Previous studies have found ankylosis occurs as a part of the inflammatory process of aseptic root resorption initiated in a rat model. The physiologic mechanisms behind the development of dentoalveolar ankylosis and healing response are still unclear. While receptor activator of nuclear factor-κβ ligand (RANKL), receptor activator of nuclear factor-κβ (RANK) and osteoprotegerin (OPG) have gained momentum in the understanding of resorption, no study to date has investigated their role in dentoalveolar ankylosis.

研究テーマ:

本研究の目的は、ラットのPDLにおいてアンキローシスが発生した時期や時期、時間の経過とともにアンキローシスが解消されるかどうかを調べ、最後にアンキローシス発生過程におけるRANKL、RANK、OPGの発現を観察することであった。

AIMS: The aims of this study were to investigate if, and when, ankylosis occurred in the rat PDL, whether the resolution of ankylosis occurred with time and, finally, to observe the expression of RANKL, RANK and OPG during the ankylotic process.

材料および方法:

8週齢の雄のSprague-Dawleyラット15匹の右上第一大臼歯冠にドライアイスを20分間塗布した。さらに3匹のラットを無処置の外部コントロールとした。3匹のラットをそれぞれ0日目、4日目、7日目、14日目、28日目の熱侮辱の後に犠牲にした。各上顎を解剖し、組織学的検査とRANKL、OPG、RANK免疫組織化学のために処理した。

MATERIALS AND METHODS: Dry ice was applied for 20 minutes to the upper right first molar crown of 15 eight-week-old, male Sprague-Dawley rats. An additional three rats served as untreated external controls. Groups of three rats were sacrificed after the thermal insult on day 0, 4, 7, 14 and 28 respectively. Each maxilla was dissected out and processed for histological examination and RANKL, OPG and RANK immunohistochemistry.

結果:

RESULTS: By the use of light microscopy and H&E staining, no ankylosis was detected in the external control group and the experimental groups at days 0 and 4. On day 7, disruption within the periodontal ligament was observed in the interradicular region and the initial signs of ankylosis were seen in the form of finger-like projections extending from the alveolar bone towards the cementum. Fourteen days after the thermal insult, all animals exhibited extensive ankylosis that spanned the entire interradicular periodontal space. At 28 days, the development of ankylosis appeared to have ceased and repair was observed, together with an intact periodontal ligament in all but one rat. Positive staining results were obtained with RANKL, RANK and OPG antibodies. The expressions of RANKL, RANK and OPG were similar in the external control group, 0-, 4-, and 28-day experimental groups. In the 7- and 14-day experimental groups, RANKL, RANK and OPG were expressed in the blood vessels within the ankylotic regions.

結論:

アンキローシスの発症とその解決の過程で、RANKL、RANK、OPGの間には複雑な相互作用が存在しており、今後の研究が必要であると結論づけられました。

CONCLUSIONS: During the development of ankylosis and its resolution, it was concluded from their simultaneous presence that there is a complex interaction between RANKL, RANK and OPG that requires further investigation.