STAT3正向调控正畸牙移动速率与牙槽骨骨量

Signal transducer and activator of transcription 3 positively modulates orthodontic tooth movement speed and alveolar bone mass

目的探讨信号转导与转录激活因子3(signal transducer and activator of transcription 3,STAT3)在牙移动中的作用,为改善正畸牙槽骨塑建与重建提供证据。方法体内实验选取8周龄雄性大鼠建立正畸牙移动模型,分为对照组(牙移动)、实验组(牙移动加STAT3抑制剂stattic局部注射),于牙移动的第7天、第14天收集实验区域牙槽骨标本进行micro-CT扫描,评估骨体积分数(bone volume/tissue volume,BV/TV)、骨小梁数目(trabecular number,Tb.N)、骨小梁厚度(trabecular thickness,Tb.Th)、骨小梁分离度(trabecular separation,Tb.Sp)、骨密度(bone mineral density,BMD),测量牙移动量。体外实验选取小鼠成骨前体细胞MC3T3-e1和小鼠单核巨噬细胞白血病细胞RAW264.7于Transwell^■培养板共培养3d,分为对照组(空白)和实验组(加入STAT3抑制剂stattic);以碱性磷酸酶(alkaline phosphatase,ALP)染色检测成骨分化;抗酒石酸酸性磷酸酶(tartrate-resistant acid phosphatase,TRAP)染色检测破骨分化;qRT-PCR检测成骨细胞核因子κB受体活化因子配体(receptor activator of nuclear factor-κB ligand,RANKL)、骨保护素(osteoprotegerin,OPG)mRNA表达。结果实验组牙槽骨骨体积分数(BV/TV)、骨小梁数目(Tb.N)、骨小梁厚度(Tb.Th)、骨密度(BMD)在第14天时较对照组明显降低,Tb.Sp在第14天时明显增高;以上指标第7天时的2组间差异无统计学意义。与对照组相比,实验组牙移动量在第7天时明显减少,差异有统计学意义(P<0.05);第14天时2组牙移动量差异无统计学意义(P>0.05)。体外实验ALP染色和TRAP染色显示,抑制剂同时抑制成骨和破骨分化;qRT-PCR结果显示,抑制剂抑制成骨前体细胞RANKL、OPG mRNA表达,升高RANKL/OPG mRNA比值。结论抑制STAT3的激活可导致成骨、破骨活动同时被抑制,使正畸牙移动速率减慢、牙槽骨骨质疏松。STAT3可能在调控正畸牙槽骨塑建与重建中发挥重要作用。

ObjectiveTo elucidate the role of signal transducer and activator of transcription 3 on orthodontic tooth movement,aiming at providing evidence for improving orthodontic bone modeling and remodeling.Methods Orthodontic tooth movement(OTM) models were established in 8-week-old Wistar rats,which were divided into 2 groups: the control group(tooth movement) and the test group(tooth movement with local injection of STAT3 inhibitorstattic). Rats were sacrificed on day 7 and 14. Micro-CT scanning was conducted to measure bone volume/tissue volume (BV/TV),trabecular number(Tb.N),trabecular thickness(Tb.Th),trabecular separation(Tb.Sp),and bone mineral densi-ty(BMD),and the amount of tooth movement of the specimens. The mouse preosteoblastic cell line MC3 T3-e1 andmononuclear macrophagic leukemia cell line RAW264.7 were cocultured in Transwell^■ culture plates and divided intothe control group(blank) and the test group(STAT3 inhibitor stattic was added). Alkaline phosphatase(ALP) stainingand tartrate-resistant acid phosphatase(TRAP) staining were carried out to reveal osteoblastic and osteoclastic differenti-ation,respectively. qRT-PCR was performed to evaluate mRNA expression levels of the receptor activator of nuclear fac-tor-κB ligand(RANKL) and osteoprotegerin(OPG) in the MC3 T3-e1 cells.ResultsCompared with the control group,in the test group,the alveolar bone at the OTM site showed a significant decrease in the BV/TV,Tb.N,Tb.Th,and BMDindexes and a significant increase in Tb.Sp on day 14,while there was no significant difference in the above indexes be-tween the two groups on day 7. The amount of tooth movement was significantly smaller in the test group on day 7 butshowed no difference on day 14. ALP staining and TRAP staining revealed weakened osteoblastic and osteoclastic differ-entiation in the test group. qRT-PCR demonstrated the inhibitor inhibited the m RNA expression of RANKL and OPGand increased the mRNA ratio of RANKL/OPG in osteogenic precursor cells.ConclusionSuppression of STAT3 acti-vation leads to inhibition of both osteoblastic and osteoclastic differentiation,resulting in lowered tooth movement andcatabolic effects on alveolar bone. STAT3 may play an important role in orthodontic bone modeling and bone remodeling.