Abstract: Objective To investigate the expression and function of the TNF signaling pathway in the early stage of orthodontic tooth movement with periodontitis and to provide evidence to study the early inflammatory response in patients with periodontitis orthodontic treatment. Methods Sixteen SD rats were randomly divided into four groups: group A--12 h of orthodontic tooth movement of the bilateral maxillary first molars in rats with periodontitis; group B--periodontitis model of the bilateral maxillary first molars without orthodontic tooth movement; group C--12 h of orthodontic tooth movement of the same teeth in rats with healthy periodontium; group D--control group without operations. The bilateral maxillary first molars and surrounding periodontal tissue of each group were collected for gene chip detection. Pathway enrichment analysis, qRT-PCR and GO (gene ontology) analysis were performed to identify differential genes involved in the TNF signaling pathway. Results Gene chip results showed that the TNF signaling pathway was significantly upregulated in group A, group B and group C (P <0.01). Among the differential genes involved in the pathway, 28 were upregulated and 5 were downregulated in group A, 12 were upregulated and 4 were downregulated in group B, and 12 were upregulated and 1 was downregulated in group C (P <0.05). The most significant GO items included "response to lipopolysaccharide", "inflammatory response", "positive regulation of NF-κB transcription factor activity", "positive regulation of NF-κB import into nucleus" and "response to hypoxia"(P <0.001). qRT-PCR results showed no significant difference in TNF-α mRNA expression in group C compared with that in group D, TNF-α was upregulated in both groups A and B (P <0.01), and mRNA expression decreased in the following order: group A > group B > group C (P <0.05). Compared with group D, the expression levels of prostaglandin-endoperoxide synthase 2 (PTGS2) and interleukin-6 ( IL-6) in groups A, B and C were significantly upregulated (P <0.05), but the expression levels of PTGS2 and IL-6 in group A were lower than those in group B (P < 0.05). Conclusion The TNF signaling pathway is activated in the early stage of orthodontic tooth movement in rats with periodontitis. The pathway products participate in many biological processes and play an important role in the inflammatory response and bone absorption.

Key words: orthodontic tooth movement, periodontitis, rats, inflammatory response, tumor necrosis factor, NF-kB transcription factor, signaling pathway, gene ontology analysis

摘要： 目的 探究肿瘤坏死因子（tumor necrosis factor,TNF）信号通路在牙周炎正畸牙移动初期的表达和功能,为牙周炎正畸患者早期炎症反应的调控机制研究提供证据。方法 SD大鼠16只随机分为4组,A组建立双侧上颌第一磨牙牙周炎正畸模型,加力12 h,初始力为80 g;B组仅建立双侧上颌第一磨牙牙周炎模型,不加力;C组对双侧上颌第一磨牙建立健康牙周正畸模型,加力12 h,初始力为80 g;D组为正常大鼠,不作处理（为对照组）。建模及加力完成后,截取各组双侧上颌第一磨牙及牙周组织作为样本进行基因芯片检测,对TNF信号通路相关差异基因进行信号通路富集分析、基因本体（gene ontology,GO）分析和qRT-PCR验证。结果 基因芯片结果显示,A、B、C组中TNF信号通路均显著性上调（P <0.01）,参与通路的基因在A组有28个上调,5个下调,B组有12个上调,4个下调,C组有12个上调,1个下调（P <0.05）。GO分析中显著性最高的GO条目为“对脂多糖的应答”、“炎症反应”、“NF-κB转录因子活性的正调控”、“NF-κB进入细胞核的正调控”、“对缺氧的应答”（P <0.001）。qRT-PCR检测结果显示,相较于对照组,C组TNF-α表达量无差异（P > 0.05）,A组、B组显著性上调（P <0.01）,A组>B组>C组（P<0.05）;相较于对照组,A、B、C组前列腺素内过氧化物合成酶2（prostaglandin-endoperoxide synthase 2,PTGS2）、白细胞介素-6（interleukin-6,IL-6）表达量均上调,差异具有统计学意义（P <0.05）,但A组PTGS2和IL-6的表达量低于B组（P <0.05）。结论大鼠牙周炎正畸牙移动早期激活TNF信号通路,参与多种生物学过程,并在炎症反应和骨吸收过程中起重要作用。

关键词: 正畸牙移动, 牙周炎, 大鼠, 炎症反应, 肿瘤坏死因子, NF-kB转录因子, 信号通路, 基因本体分析