微小RNA介导的牙周炎与动脉粥样硬化相关机制的研究进展

牙周炎是一种主要由菌斑生物膜所引起的牙周支持组织慢性炎症破坏性疾病,与宿主的免疫反应相关。牙周致病菌可通过一过性菌血症进入血液循环系统,引发血管炎症反应,增加心血管疾病患病风险。微小RNA(microRNA)作为近年来小分子RNA的研究热点,可在表观遗传学水平调控基因表达,参与炎症调节。本文综述了牙周致病菌通过microRNA调控免疫炎症反应的机制,从而介导动脉粥样硬化的发生、发展,为牙周炎与动脉粥样硬化疾病关联的分子机制研究提供新的思路。此外,通过探索动脉粥样硬化与牙周炎相关特异性microRNA的表达模式,可为未来诊断或治疗心血管疾病提供新的参考。     

微小RNA与口腔疾病

微小RNA（miRNA）是非编码单链小分子RNA,主要参与转录后调节过程,其表达谱的变化与诸多疾病（如癌症、慢性炎症等）的发生、发展密切相关。文章就miRNA的起源及其与口腔几种常见疾病的关系做一综述。     

微小RNA与肿瘤

微小RNA是一族非编码小RNA,具有极为重要的基因调控作用。微小RNA在肿瘤的发生、发展中具有癌基因和抑癌基因的功能,并且在不同的肿瘤当中具有特异性的表达谱。下面就微小RNA的形成、与肿瘤的关系、目前的研究现状等作一综述。     

微小RNA对成骨调控作用的研究进展

] 成骨细胞的分化和功能调控需由体内多种激素和局部产生的细胞因子协同完成。miRNAs (microRNAs) 是单股非编码的 RNAs 小分子,长度在 20~24个核苷酸大小。它通过与目标 RNA 基因的特定序列结合,参与基因转录后水平的调控。研究表明,miRNA 能够调控成骨细胞、破骨细胞和软骨细胞的增殖和分化,维持骨形成和骨吸收的平衡,调控软骨的骨化,是生物器官发育和某些骨代谢疾病的重要调控因子。miRNA 的发现, 揭示了基因组非编码区域蕴涵着重要的功能。因此,利用 miRNA治疗临床骨代谢疾病和修复骨缺损具有潜在的临床应用前景。本文对 miRNA 在骨形成过程中的调控作用及其研究进展作一综述。     

微小RNA在口腔扁平苔藓中的作用

微小RNA家族在调控基因表达中的重要作用日益受到关注,其调控的基因涉及细胞增殖、凋亡、生长、分化和代谢、血管化和免疫应答等多种生物过程,其表达谱和表达量的变化与多种疾病如肿瘤、炎症性疾病、自身免疫性疾病的发生、发展密切相关.本文对口腔扁平苔藓中微小RNA的研究现状作一综述.     

微小RNA21与干细胞之间的关系

微小RNA（miRNA）参与早期胚胎发生以及细胞增殖和分化、细胞生存和程序性死亡、细胞代谢和能量平衡等一系列重要的生命过程。其中,miRNA21通过调节转化生长因子（TGF）β-Smad信号转导通路促进间质干细胞（MSC）成脂分化和抑制人脂肪源干细胞增殖。骨形态发生蛋白（BMP）受体（BMPR）2为BMP9诱导干细胞成骨分化所必需,而BMPR2是miRNA21的作用标靶,即miRNA21与干细胞成骨分化相关。在MSC分化过程中, miRNA21通过抑制萌芽（SPRY）1和SPRY2蛋白表达,调节细胞外信号调节激酶-促丝裂原激活蛋白激酶信号转导通路活性的大小和持续时间,增加MSC的分化潜能。miRNA21过表达可以促进低氧或无血清条件下MSC的生存,而下调miRNA21则会加快MSC程序性死亡。明确miRNA21的生物学功能及其对干细胞分化的调控机制,旨在为干细胞在组织工程技术和疾病防治等方面的应用奠定依据。     

微小RNA与口腔癌前病变

微小RNA是非编码单链小分子RNA,通常在转录后水平通过降解抑制目标信使RNA参与基因调控,目前研究发现微小RNA与口腔癌关系密切,在某些口腔癌前疾病的癌变过程中发挥着重要作用,此文就微小RNA与口腔癌前病变的关系作一综述。     

伴牙槽嵴吸收的牙周炎患者上前牙龈乳头缺陷程度影响因素初探

目的:探讨有牙槽嵴吸收时上前牙不同程度龈乳头缺陷的相关影响因素。方法:选择2019年6至12月就诊于北京大学口腔医学院·口腔医院牙周科,且经治疗后牙周炎控制稳定并定期进行牙周维护的14例牙周炎患者的64个上前牙龈乳头,通过标准化临床图像及锥形束CT影像资料综合分析,评价邻接触点至骨嵴顶的距离（distance from...     

微小RNA调控靶基因作用机制的研究进展

微小RNA是一类通过转录后调控机制对基因进行调控的非编码的短链RNA。研究发现微小RNA的功能涉及多种生物学过程,与肿瘤的发生、发展和多种疾病密切相关。本文就微小RNA形成过程及对靶基因调控机制的研究进展作一综述。     

牙髓干细胞对牙周炎中破骨细胞的作用

目的研究牙髓干细胞（DPSC）对牙周炎中破骨细胞形成及牙槽骨再生的影响,并初步探索DPSC对小鼠破骨细胞的作用机制。 方法体外诱导小鼠骨髓单核细胞破骨分化,观察破骨细胞组（OC组）及其与DPSC共培养组（OC+DPSC组）的抗酒石酸酸性磷酸酶（TRAP）染色情况,实时荧光定量聚合酶链反应（PCR）检测破骨分化相关基因包括活化T细胞核因子（NFATc1）、基质金属蛋白酶9（MMP-9）及TRAP的表达差异。体内构建小鼠慢性牙周炎模型,通过微计算机体层摄影（micro-CT）扫描后三维重建,比较慢性牙周炎+0.9%氯化钠溶液注射组（NS组）和慢性牙周炎+DPSC注射组（DPSC组）釉牙骨质界至牙槽嵴顶（CEJ-ABC）距离,并对标本进行苏木精-伊红和TRAP染色,观察DPSC对小鼠破骨细胞及牙槽骨再生的影响。采用SPSS 20.0软件进行数据统计分析,采用独立样本t检验及校正t检验分析组间差异。 结果体外TRAP染色发现,与DPSC共培养明显抑制成熟破骨细胞形成,OC+DPSC组成熟破骨细胞均数（4.2 ± 0.2）少于OC组均数（6.8 ± 0.2）,差异有统计学意义（t= 15.922,P<0.001）;破骨细胞表面积均数（0.046 ± 0.007）mm²也明显小于OC组（0.763 ± 0.015）mm²,差异有统计学意义（t = 83.174,P<0.001）。相对OC组,OC+DPSC共培养组的MMP-9、NFATc1及TRAP的mRNA相对表达量明显降低,均值分别为0.38 ± 0.17（t = 6.217,P = 0.003）、0.24 ± 0.12（t = 10.569,P = 0.003）和0.55 ± 0.13（t = 6.077,P = 0.026）。micro-CT扫描结果显示,DPSC注射组CEJ-ABC的平均距离为（0.215 ± 0.017）mm,明显小于0.9%氯化钠溶液组（0.311 ± 0.022）mm,差异有统计学意义（t= 10.921,P<0.001）,组织学观察下DPSC组炎症反应较0.9%氯化钠溶液组轻,且破骨细胞更少。 结论DPSC可通过抑制牙周炎破骨细胞的形成从而促进牙槽骨再生,有望作为一种可局部注射的骨代谢双向调节生物制剂,治疗临床上包括牙周炎等因骨代谢失衡引起的炎症性骨吸收疾病。     

侵袭性牙周炎牙槽骨吸收状况及相关因素分析

目的 评价未经治疗的侵袭性牙周炎(aggressive periodontitis,AgP)患者牙槽骨吸收状况并分析与牙槽骨吸收状况有关的因素,以期为临床提供参考.方法 对108例未经治疗的AgP患者[男45例,女63例;年龄≤25岁者34例(A组),＞25岁者74例(B组)]进行吸烟状况和教育背景的问卷调查,并测量全口牙邻面位点探诊深度(probing depth,PD,浅袋:PD=3、4 mm,中袋:PD=5、6 mm,深袋:PD≥7 mm);根据全口X线根尖片评价邻面牙槽骨吸收状况(轻、中、重度骨吸收).结果 实际共测量了2841颗牙.浅袋与轻度骨吸收(r=0.518,P=0.000)、深袋与重度骨吸收(r=0.366,P=0.000)均呈正相关;AgP患者男性轻、中、重度骨吸收牙数(分别为7.1±6.2、12.5±4.7、5.1±0.6)与女性(分别为8.7±6.3、12.9±4.8、4.2±0.5)差异无统计学意义(P值分别为0.707、0.671和0.413);B组中、重度骨吸收牙数(分别为13.6±4.2、5.2±3.7)显著多于A组(分别为11.0±5.5、3.6±3.5),P＜0.01;受过高等教育和未受高等教育者轻、中、重度骨吸收牙数差异无统计学意义(P值为0.314、0.862和0.407);吸烟是重度骨吸收AgP患者的危险因素之一(OR=1.961).结论 AgP患者PD与牙槽骨吸收程度相关;年龄和吸烟是影响AgP患者牙槽骨吸收的重要因素.     

氯化镧对大鼠实验性牙周炎的治疗作用

目的:评估镧盐对大鼠实验性牙周炎临床症状以及骨吸收的影响。方法:选健康SD大鼠68只,用外科缝线结扎左侧上颌第二磨牙(M2)颈部并予10%高糖水每日喂养,诱导形成大鼠牙周炎模型。结扎4周后随机选4只大鼠处死,取左侧上颌M2牙周组织块制作切片,观察牙周炎模型建立情况。将造模成功的大鼠随机分成4组,每组16只:生理盐水冲洗对照组(P组);氯己定冲洗组(P1组);镧盐冲洗组(P2组);镧盐喂养组(P3组)。每4周测量各组大鼠临床指标,与治疗前自身对照。治疗3个月后,处死各组大鼠并取左上颌M2牙周组织块制作标本,用体视镜观察并测量牙槽骨吸收情况。结果:治疗后P1、P2、P3组各临床指标较治疗前均有所下降(P<0.05),P组PD、TM虽有下降趋势,但差异无显著性。各组间比较P3组牙槽骨吸收值与面积值较P组显著减少(P<0.05)。结论:0.12%复方氯己定、0.1 mmol/L镧盐水冲洗及0.01 mmol/L镧盐喂养对大鼠牙周炎临床症状的改善效果明显,镧盐喂养对缓解牙槽骨吸收有一定作用。     

Effects of glucocorticoid-induced osteoporosis on bone tissue of rats with experimental periodontitis

ObjectiveTo evaluate the effects of osteoporosis induced by glucocorticoid (GIOP) on bone tissue of rats with experimental periodontitis (EP).Design48 male Wistar rats divided into groups: Naïve, EP, GIOP and GIOP + EP. Rats of GIOP and GIOP + EP groups received 7 mg/kg of dexamethasone intramuscularly once a week for 5 weeks. Following, EP and GIOP + EP groups were subjected to ligature-induced periodontitis. Naïve group experienced no manipulation. After 11 days, the animals were euthanized and left maxillae collected for macroscopic, radiographic, micro-tomographic and microscopic analysis of alveolar bone loss (ABL). Blood samples were collected for determination of bone-specific alkaline phosphatase (BALP) levels and the right femurs were removed for radiographic and biomechanical analysis.ResultsEP caused ABL and reduced BALP levels (p < 0,05), but it did not change the architecture or biomechanics of femur, compared to Naïve. GIOP did not cause ABL, but it significantly decreased alveolar bone mineral density (ABMD), bone percentage and trabecular thickness (Tb.Th) and increased alveolar bone porosity (p < 0.05) and significantly reduced BALP serum levels, as well as radiographic density and Young’s module of femur, compared to Naïve. There was a greater ABL in group GIOP + EP when compared to EP (p < 0.05). GIOP + EP caused a greater decrease on ABMD, Tb.Th, bone percentage and increased bone porosity (p < 0.05) and also presented a significant reduction in BALP levels (p < 0.05), in radiographic density and in Young’s module of femur compared to EP (p < 0.05).ConclusionsGIOP can potentiate the destructive effects of EP on alveolar bone and alter the systemic bone loss, by promoting bone resorption and reducing osteoblast activity.     

血清骨钙素与牙周炎的关系

目的：检测牙周炎患者血清中骨钙素含量，以期发现它与牙周炎牙槽骨病变的关系。方法：选择早发性牙周炎患者（early-onset periodontitis,EOP)31例，成人牙周炎患者（adult periodontitis,AP)21例，健康对照者35例，用放射免疫分析法测定血清骨钙素含量。结果：血清骨钙素含量EOP组（6．25ng/ml),AP组（5．89ng/ml)均显著高于健康组（3．74ng/ml)，但EOP组与AP组之间骨钙素含量无明显差异，结论：骨钙素可能作为牙周炎症病变代谢变化的标志。     

Intermittent administration of parathyroid hormone ameliorated alveolar bone loss in experimental periodontitis in streptozotocin-induced diabetic rats

ObjectiveIntermittent administration of parathyroid hormone (PTH) has been demonstrated to have anabolic effects on bone metabolism and is approved for use in the treatment of osteoporosis. This study evaluates the role of intermittent PTH administration on alveolar bone loss in streptozotocin (STZ)-induced diabetic rats.DesignFifty male Sprague Dawley rats were randomly divided into the following five groups: (1) a control group (saline placebo without ligature and STZ injection), (2) a PTH group (PTH administration without ligature and STZ injection), (3) an L group (saline placebo with ligature), (4) an L + STZ group (saline placebo with ligature and STZ injection), and (5) an L + STZ + PTH group (PTH administration with ligature and STZ injection). PTH was administered at 75 μg/kg per dose four times a week for 28 days. Subsequently, all rats were sacrificed, and their mandibles were extracted for micro-computed tomography (micro-CT) scanning, as well as histological and immunochemical evaluation.ResultsMicro-CT scanning demonstrated the anabolic effect of PTH on alveolar bone metabolism in STZ-induced diabetic rats (P < 0.05), and histomorphometry indicated that PTH inhibited inflammation of the periodontium and increased the level of osteoblastic activity (P < 0.05). Immunochemical evaluation showed that rats subjected to both ligature placement and STZ injection had the highest receptor activator of nuclear factor kappa B ligand (RANKL)/osteoprotegerin (OPG) ratio and that PTH administration decreased this ratio.ConclusionIntermittent systemic PTH administration effectively reduced alveolar bone loss and ameliorated the manifestation of experimental periodontitis in STZ-induced diabetic rats.     

Microbial profile of ligature-induced periodontitis in rats

Objective

The aim of this study was to evaluate the composition of the biofilm accumulated around ligatures in rats by checkerboard DNA-DNA hybridization using probes made from human oral bacterial species.

Methods

12 Wistar rats were selected for this study. One of the mandibular first molars of each animal received a ligature, while the contralateral tooth was left unligated to be used as a control. Forty-two days later, the ligatures and one sample of biofilm from each unligated teeth were analyzed by checkerboard DNA-DNA hybridization for 40 human periodontal species. The area of bone loss in the furcation area was determined histometrically.

Results

The unligated teeth did not present any of the bacterial species tested. Twenty five species were detected in the ligatures. Streptococcus- and Actinomyces-like species were found in high mean counts, followed by Fusobacterium-, Prevotella nigrescens- and Parvimonas micra-like species and Porphyromonas gingivalis- and Aggregatibacter actinomycetemcomitans-like species. Greater bone loss was observed in the furcation area of the ligated than of the unligated group (p < 0.0001).

Conclusion

At 42 days, the ligature biofilm in rats presents various bacterial species that hybridize to probes of periodontal bacterial species commonly observed in human.     

Extracellular ATP is a key modulator of alveolar bone loss in periodontitis

Periodontal diseases are initiated by pathogenic bacterial biofilm activity that induces a host inflammatory cells immune response, degradation of dento gingival fibrous tissue and its detachment from root cementum. It is well accepted, that osteoclastic alveolar bone loss is governed exclusively through secretion of proinflammatory cytokines. Nevertheless, our findings suggest that once degradation of collagen fibers by MMPs occurs, a drop of cellular strains cause immediate release of ATP from marginal gingival fibroblasts, cell deformation and influx of Ca + 2. Increased extracellular ATP (eATP) by interacting with P2 × 7 purinoreceptors, present on fibroblasts and osteoblasts, induces generation of receptor activator of nuclear factor kB ligand (RANKL) that further activates osteoclastic alveolar bone resorption and bone loss. In addition, increased eATP levels may amplify inflammation by promoting leukocyte recruitment and NALP3-inflammasome activation via P2 × 7. Then, the inflammatory cells secrete cytokines, interleukin IL-1, TNF and RANKL that further trigger alveolar bone resorption. Moreover, eATP can be secreted from periodontal bacteria that may further contribute to inflammation and bone loss in periodontitis. It seems therefore, that eATP is a key modulator that initiates the pathway of alveolar bone resorption and bone loss in patients with periodontal disease. In conclusion, we propose that strain release in gingival fibroblasts aligned on collagen fibers, due to activity of MMP, activates release of ATP that triggers the pathway of alveolar bone resorption in periodontitis. We predict that by controlling the eATP interaction with its cellular purinoreceptors will reduce significantly bone loss in periodontitis.     

Effect of nifedipine on gingival enlargement and periodontal breakdown in ligature-induced periodontitis in rats

Objective

A recent consensus report could not find specific reports of the effect of nifedipine on the destruction of the periodontal tissues. The aim of the present study was to evaluate the effect of nifedipine on gingival enlargement and periodontal breakdown using a ligature-induced periodontitis in rats.

Materials and methods

Fifty, male, 60 days old, Wistar rats, were divided into six groups. Cotton sutures were placed around the upper second molars. Two groups of 10 rats each did not receive ligatures and were treated daily with either saline solution or nifedipine 50 mg/kg/day. Two groups of 10 rats received ligatures and were also treated daily with saline solution or nifedipine 50 mg/kg/day. Two additional groups (nifedipine 10 and 100 mg/kg/day) were included to explore a possible dose-response relationship. Animals were euthanatised at 30 days. Internal and oral epithelium, total and inflamed connective tissue, gingival thickness and height, and bone loss were assessed histologically.

Results

Nifedipine alone was not sufficient to promote gingival enlargement or periodontal destruction in the absence of the ligature. Compared to animals with ligatures only, the group that received ligatures and nifedipine 50 mg/kg/day showed significant higher estimates for total and inflamed connective tissue, gingival thickness and height. No significant differences were observed for bone loss between these experimental groups. The other dosages of nifedipine did not provide additional information.

Conclusion

Nifedipine itself did not lead to gingival enlargement in rats. In the presence of biofilm accumulation, nifedipine yielded greater gingival enlargement and periodontal inflammation, but it did not increase periodontal destruction.     

雌激素缺乏对大鼠牙槽骨吸收影响的实验研究

目的观察雌激素缺乏对大鼠牙槽骨吸收的影响。方法34只雌性SD大鼠随机分为4组。第1组假手术(n=8),第2组卵巢切除(n=9),第3组卵巢切除加牙周结扎(n=9),第4组卵巢切除、牙周结扎加雌激素治疗(n=8)。适应性喂养7天后行假手术或双侧卵巢切除术。第4组于术后第二天起皮下注射苯甲酸雌二醇．20μg／kg体重／次,三天一次。第3、4两组于卵巢切除术后28天,结扎丝结扎上颌第一磨牙诱导牙周炎。第63天处死全部大鼠。常规取材。观察牙用组织组织学改变。测量牙用骨丧失值(PBL)。比较牙用骨支持率(PBS)。检测血清碱性磷酸酶(ALP)。结果采用成组f检验,第1、2两组的PBL分别为0．398±O．147mm,0．663±0．132哪。PBS分别为O．588±O．058。0．440±0．197,组间差异均有统计学意义(P<0．05);第2、3两组的PBL、PBS组间差异均有统计学意义(P<0．05)。第3组的PBL为0．875±0．197mm,PBS为0．336±O．087;第3、4两组的PBL、PBS组间差别没有统计学意义(P>0．05),第4组的PBL为O．823±0．119mm,PBS为0．360±0．950。结论雌激素缺乏促进牙槽骨吸收,茵斑刺激加剧骨质疏松大鼠牙槽骨的吸收,雌激素替代治疗不能预防骨质疏松大鼠因茵斑刺激引发的牙槽骨吸收。     

Protective effects of Tacrolimus, a calcineurin inhibitor, in experimental periodontitis in rats

OBJECTIVE: Periodontitis is a well-appreciated example of leukocyte-mediated bone loss and inflammation with pathogenic features similar to those observed in other inflammatory diseases, such as arthritis. Since Tacrolimus, is an immunomodulatory drug used for the treatment of some cases of arthritis, we hypothesized that it may modulate periodontal disease. DESIGN: Using a murine model of ligature-induced periodontal disease, we assessed the effects of daily administrations of Tacrolimus (1mg/kg body weight) on bone loss, enzymatic (myeloperoxidase) analysis, differential white blood cells counts, airpouch exudate and cytokine expression for 5-30 days. RESULTS: Radiographic, enzymatic (myeloperoxidase) and histological analysis revealed that Tacrolimus reduced the severity of periodontitis. More specifically, Tacrolimus suppressed the expression of serum interleukin (IL-1beta), tumour necrosis factor (TNF-alpha), IL-6, airpouch exudate PGE(2) and leukocytosis usually observed after the induction of periodontitis. Tacrolimus treatment in periodontitis-induced rats conferred protection against the inflammation-induced tissue and bone loss associated with periodontitis, through a mechanism involving IL-1beta, TNF-alpha and IL-6. CONCLUSIONS: The effects of Tacrolimus on periodontal disease pathogenesis may provide clues to a novel approach to host modulation therapy in destructive periodontal disease.