Model Of Orthodontic Tooth Movement Research Articles

Semaphorin 3A regulates alveolar bone remodeling on orthodontic tooth movement

Semaphorin 3A (Sema3A) promotes osteoblast differentiation and inhibits osteoclast differentiation. In the present study, we observed the regulation of alveolar bone remodeling by Sema3A during orthodontic tooth movement (OTM). Four inflammatory cytokines (IL-1β, IL-6, TNFα, and INF-γ) involved in OTM were applied to osteoblasts in vitro, and Sema3A expression was determined by reverse-transcription quantitative polymerase chain reaction (RT-qPCR). In vivo, springs were attached to the maxillary first molars of C56BL/6J mice (OTM model) and the localization of Sema3A was confirmed by immunofluorescent. Recombinant Sema3A (rSema3A) was locally injected into the OTM model. Inflammatory cytokine localization in the OTM model was confirmed by immunohistochemistry. In vivo, more Sema3A was observed on the tension side in the OTM group. Injection of rSema3A into the OTM model increased mineralization on the tension side and decreased the number of osteoclasts on the compression side. In vitro, IL-1β significantly increased Sema3A mRNA levels. Immunohistochemistry for IL-1β in vivo showed more concentrated staining in the periodontal ligament on the tension side than on the compression side. In summary, our findings revealed the distribution of Sema3A in the periodontal ligament and demonstrated that rSema3A administration promotes bone formation and inhibits bone resorption during OTM.

Biocompatible reduced graphene oxide stimulated BMSCs induce acceleration of bone remodeling and orthodontic tooth movement through promotion on osteoclastogenesis and angiogenesis.

We has synthesized the biocompatible gelatin reduced graphene oxide (GOG) in previous research, and in this study we would further evaluate its effects on bone remodeling in the aspects of osteoclastogenesis and angiogenesis so as to verify its impact on accelerating orthodontic tooth movement. The mouse orthodontic tooth movement (OTM) model tests in vivo showed that the tooth movement was accelerated in the GOG local injection group with more osteoclastic bone resorption and neovascularization compared with the PBS injection group. The analysis on the degradation of GOG in bone marrow stromal stem cells (BMSCs) illustrated its good biocompatibility in vitro and the accumulation of GOG in spleen after local injection of GOG around the teeth in OTM model in vivo also didn't influence the survival and life of animals. The co-culture of BMSCs with hematopoietic stem cells (HSCs) or human umbilical vein endothelial cells (HUVECs) in transwell chamber systems were constructed to test the effects of GOG stimulated BMSCs on osteoclastogenesis and angiogenesis in vitro. With the GOG stimulated BMSCs co-culture in upper chamber of transwell, the HSCs in lower chamber manifested the enhanced osteoclastogenesis. Meanwhile, the co-culture of GOG stimulated BMSCs with HUVECs showed a promotive effect on the angiogenic ability of HUVECs. The mechanism analysis on the biofunctions of the GOG stimulated BMSCs illustrated the important regulatory effects of PERK pathway on osteoclastogenesis and angiogenesis. All the results showed the biosecurity of GOG and the biological functions of GOG stimulated BMSCs in accelerating bone remodeling and tooth movement.

Osteocytes Enhance Osteogenesis by Autophagy-Mediated FGF23 Secretion Under Mechanical Tension.

Mechanical stimuli control cell behaviors that are crucial for bone tissue repair. Osteocytes sense extracellular mechanical stimuli then convert them into biochemical signals to harmonize bone remodeling. However, the mechanisms underlying this process remain unclear. Autophagy, which is an evolutionarily preserved process, that occurs at a basal level when stimulated by multiple environmental stresses. We postulated that mechanical stimulation upregulates osteocyte autophagy via AMPK-associated signaling, driving osteocyte-mediated osteogenesis. Using a murine model of orthodontic tooth movement, we show that osteocyte autophagy is triggered by mechanical tension, increasing the quantity of LC3B-positive osteocytes by 4-fold in the tension side. Both in vitro mechanical tension as well as the chemical autophagy agonist enhanced osteocyte Fibroblast growth factor 23 (FGF23) secretion, which is an osteogenenic related cytokine, by 2-and 3-fold, respectively. Conditioned media collected from tensioned osteocytes enhanced osteoblast viability. These results indicate that mechanical tension drives autophagy-mediated FGF23 secretion from osteocytes and promotes osteogenesis. Our findings highlight a potential strategy for accelerating osteogenesis in orthodontic clinical settings.

PLC, PTH and NF-κB increased during orthodontic bone remodeling in chronic stress rats

This study was designed to investigate the potential effects of chronic stress on periodontal bone remodeling and its mechanism during orthodontic tooth movement in rats. Forty-eight male SD rats aged 8 weeks were randomly divided into control group and chronic stress group. Chronic unpredictable mild stress model (CUMS) was established in the stress group, which was validated by behavioral experiment as well as cortisol (CORT) and adrenocorticotropic hormone (ATCH) levels. Then, the two groups were further divided into three distinct groups, namely group with no orthodontic force, group with 30 g orthodontic force and group with 50 g orthodontic force respectively to construct orthodontic tooth movement model. The rats were sacrificed after 14 days and maxilla on the loading side was obtained to measure tooth movement distance. It was found that compared with the control group, the chronic stress group displayed increased parathyroid hormone (PTH), amino terminal peptide of type I procollagen (PINP) and c-terminal peptide of type I collagen branch (CTX) levels as measured by enzyme-linked immunosorbent assay (ELISA). Hematoxylin and Eosin (HE) and TRAP staining showed fewer osteoblasts and more number of osteoclasts. The results of western blot showed no significant change in expression of Adenylate cyclase (AC) but increased phospholipase C (PLC) levels were noted. In addition, increased NF-κB expression was observed by immunohistochemistry. Overall, chronic stress can affect bone remodeling during orthodontic tooth movement by increasing the content of PTH in the blood and increasing PLC and NF-κB.

Compressive force-induced LincRNA-p21 inhibits mineralization of cementoblasts by impeding autophagy.

The mineralization capability of cementoblasts is the foundation for repairing orthodontic treatment-induced root resorption. It is essential to investigate the regulatory mechanism of mineralization in cementoblasts under mechanical compression to improve orthodontic therapy. Autophagy has a protective role in maintaining cell homeostasis under environmental stress and was reported to be involved in the mineralization process. Long noncoding RNAs are important regulators of biological processes, but their functions in compressed cementoblasts during orthodontic tooth movement remain unclear. In this study, we showed that compressive force downregulated the expression of mineralization-related markers. LincRNA-p21 was strongly enhanced by compressive force. Overexpression of lincRNA-p21 downregulated the expression of mineralization-related markers, while knockdown of lincRNA-p21 reversed the compressive force-induced decrease in mineralization. Furthermore, we found that autophagy was impeded in compressed cementoblasts. Then, overexpression of lincRNA-p21 decreased autophagic activity, while knockdown of lincRNA-p21 reversed the autophagic process decreased by mechanical compression. However, the autophagy inhibitor 3-methyladenine abolished the lincRNA-p21knockdown-promoted mineralization, and the autophagy activator rapamycin rescued the mineralization inhibited by lincRNA-p21 overexpression. Mechanistically, the direct binding between lincRNA-p21 and FoxO3 blocked the expression of autophagy-related genes. In a mouse orthodontic tooth movement model, knockdown of lincRNA-p21 rescued the impeded autophagic process in cementoblasts, enhanced cementogenesis, and alleviated orthodontic force-induced root resorption. Overall, compressive force-induced lincRNA-p21 inhibits the mineralization capability of cementoblasts by impeding the autophagic process.

Orthodontic force regulates metalloproteinase-3 promoter in osteoblasts and transgenic mouse models

Background/purposePreviously we demonstrated up-regulation of matrix metalloproteinase-3 (MMP-3) in human osteoblasts under compression and in bony specimens of experimental orthodontic tooth movement (OTM). Here, we studied the temporal characteristics of compression stimulation in human and mouse osteoblast cell lines, and generated a transgenic mouse model for assessing the MMP-3 expression during OTM. Materials and methodsWe investigated MMP-3 expressions in human and murine osteoblasts through RT-PCR and luciferase assay, after compressive force loading. Inhibitors were added to identify the possible mechanisms for signal transduction. A human MMP-3 promoter was isolated, cloned and transfected to generate a transgenic mouse with a green fluorescent protein reporter. OTM was then initiated to observe the location and time course of transcriptional regulation of MMP-3 signals. ResultsWe found changes in the transcription of MMP-3 in response to mechanical force applied to both human and mouse osteoblast cell lines, suggesting that the response is positive across species. Cloned human MMP-3 promoter may cause the response of luciferase to 1% compression. Moreover, p38 inhibitor exerted a down-regulatory effect on MMP-3 promoter expression, although the inhibitory effect didn't reach a significant level. In the transgenic mouse OTM model, we again found increased expression of MMP-3 in response to mechanical force loading around the periodontal ligament. ConclusionMechanical force can stimulate MMP-3 expression, possibly through the p38 MAPK pathway, with its strongest signal occurring at 24 h. The mechanical responsiveness in MMP-3 promoter regions can be observed in both humans and rodents in vitro and in vivo.

Orthodontic tooth movement alters cementocyte ultrastructure and cellular cementum proteome signature.

Cementum is a mineralized tissue that covers tooth roots and functions in the periodontal attachment complex. Cementocytes, resident cells of cellular cementum, share many characteristics with osteocytes, are mechanoresponsive cells that direct bone remodeling based on changes in loading. We hypothesized that cementocytes play a key role during orthodontic tooth movement (OTM). To test this hypothesis, we used 8-week-old male Wistar rats in a model of OTM for 2, 7, or 14days (0.5N), whereas unloaded contralateral teeth served as controls. Tissue and cell responses were analyzed by high-resolution micro-computed tomography, histology, tartrate-resistant acid phosphatase staining for odontoclasts/osteoclasts, and transmission electron microscopy. In addition, laser capture microdissection was used to collect cellular cementum, and extracted proteins were identified by liquid chromatography coupled to tandem mass spectrometry. The OTM model successfully moved first molars mesially more than 250μm by 14days introducing apoptosis in a small number of cementocytes and areas of root resorption on mesial and distal aspects. Cementocytes showed increased nuclear size and proportion of euchromatin suggesting cellular activity. Proteomic analysis identified 168 proteins in cellular cementum with 21 proteins found only in OTM sites and 54 proteins only present in control samples. OTM-down-regulated several extracellular matrix proteins, including decorin, biglycan, asporin, and periostin, localized to cementum and PDL by immunostaining. Furthermore, type IV collagen (COL14A1) was the protein most down-regulated (-45-fold) by OTM and immunolocalized to cells at the cementum-dentin junction. Eleven keratins were significantly increased by OTM, and a pan-keratin antibody indicated keratin localization primarily in epithelial remnants of Hertwig's epithelial root sheath. These experiments provide new insights into biological responses of cementocytes and cellular cementum to OTM.

Probiotic Bifidobacterium animalis subsp. lactis consumption slows down orthodontic tooth movement in mice

IntroductionProbiotics are live microorganisms that, when consumed in appropriate amount, can provide health benefits. Although many studies have shown positive results with the use of probiotics in bone loss control, as in periodontal disease, the effect of probiotics on a mechanical force-induced alveolar bone resorption is still unknown. Therefore, this study aimed to investigate the impact of the specific probiotic Bifidobacterium animalis subsp. lactis on bone remodeling induced by orthodontic tooth movement. MethodsFor this study, thirty C57BL6/J male mice were used and divided into two groups: 1- Mice were orally treated with the probiotic; 2- Mice were treated with vehicle. All mice were submitted to the experimental model of orthodontic tooth movement (OTM). Bone parameters and OTM was evaluated by MicroCT. OTM and TRAP positive cells were analyzed by histomorphometric analysis. Osteoclasts markers were evaluated by qPCR and short chain fatty acids were measured in feces. ResultsMicro-CT analysis showed that probiotic treatment did not modify the alveolar bone parameters. However, supplementation with probiotics restrained the tooth movement, as demonstrated by the reduced distance of OTM. Probiotic-treated mice presented down-regulation of Trap expression and reduced osteoclast numbers compared to the control. Accordingly, probiotics supplemented mice exhibited a higher concentration of short-chain fatty acid in their feces. ConclusionsThe supplementation with Bifidobacterium animalis subsp. lactis impaired tooth movement without altering the alveolar bone microarchitecture. The effect on bone remodeling induced by Bifidobacterium animalis subsp. lactis may be associated with the short-chain fatty acids' production.

Mechanosensitive Piezo1 in Periodontal Ligament Cells Promotes Alveolar Bone Remodeling During Orthodontic Tooth Movement.

Orthodontic tooth movement (OTM) is a process depending on the remodeling of periodontal tissues surrounding the roots. Orthodontic forces trigger the conversion of mechanical stimuli into intercellular chemical signals within periodontal ligament (PDL) cells, activating alveolar bone remodeling, and thereby, initiating OTM. Recently, the mechanosensitive ion channel Piezo1 has been found to play pivotal roles in the different types of human cells by transforming external physical stimuli into intercellular chemical signals. However, the function of Piezo1 during the mechanotransduction process of PDL cells has rarely been reported. Herein, we established a rat OTM model to study the potential role of Piezo1 during the mechanotransduction process of PDL cells and investigate its effects on the tension side of alveolar bone remodeling. A total of 60 male Sprague-Dawley rats were randomly assigned into three groups: the OTM + inhibitor (INH) group, the OTM group, and the control (CON) group. Nickel-titanium orthodontic springs were applied to trigger tooth movement. Mice were sacrificed on days 0, 3, 7, and 14 after orthodontic movement for the radiographic, histological, immunohistochemical, and molecular biological analyses. Our results revealed that the Piezo1 channel was activated by orthodontic force and mainly expressed in the PDL cells during the whole tooth movement period. The activation of the Piezo1 channel was essential for maintaining the rate of orthodontic tooth movement and facilitation of new alveolar bone formation on the tension side. Reduced osteogenesis-associated transcription factors such as Runt-related transcription factor 2 (RUNX2), Osterix (OSX), and receptor activator of nuclear factor-kappa B ligand (RANKL)/osteoprotegerin (OPG) ratio were examined when the function of Piezo1 was inhibited. In summary, Piezo1 plays a critical role in mediating both the osteogenesis and osteoclastic activities on the tension side during OTM.

Apolipoprotein E is an effective biomarker for orthodontic tooth movement in patients treated with transmission straight wire appliances

Orthodontic tooth movement (OTM) is the core component of orthodontic treatment and is increasingly popular for treating malocclusions. In this study, we aimed to investigate the role of apolipoprotein E (ApoE) in OTM.Thirty patients treated with transmission straight wire technology were selected and longitudinally tracked at 2 different stages of orthodontic treatment (initial 2 months and 12 months of orthodontic treatment). Total saliva was collected and analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Western blotting was used to detect the difference in ApoE expression in the saliva samples of the 2 groups. The expression of ApoE was further verified by immunohistochemical staining in a mouse model of tooth movement.The results of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry showed significant differences in the components of the salivary peptides in the 2 groups and peptides with a molecular weight of 2010.7 Da were predicted to be ApoE by database analysis. Western blotting further verified a significant difference in the expression of salivary ApoE in the 2 groups. In addition, an OTM model was successfully constructed in mice. The immunohistochemical staining results showed that ApoE expression significantly increased after force loading in the OTM model.This study indicated that ApoE participated in and played a role during OTM in patients treated with transmission straight wire technology. This relationship might be related to alveolar bone reconstruction and root resorption. The results provide new ideas for research on the mechanism of tooth movement using precision medicine based on saliva detection.

Effect of humic acid as a photosensitizer combined with low-energy laser on orthodontic tooth movement in rats

Background/purposeHumic acid (HA) could promote light conversion reaction, and lasers accelerate orthodontic tooth movement. We investigated the effect of HA, as a photosensitizer, combined with low-energy laser on orthodontic tooth movement in rats. Materials and methodsAn orthodontic tooth movement model was established, and the upper left first molar was moved mesially by a nickel-titanium tension spring with a 50-g force. HA was injected into the rats’ abdominal cavity (80 mg/kg once daily). The periodontal tissue of the upper left upper first molar on the pressure side was irradiated (50 s once every 2 days) using a semiconductor laser (wavelength, 650 nm; power, 50 mV). Distance moved by the upper left first molar was measured at different time points, and the tissue of the first molar was sectioned and scanned by micro-computed tomography to evaluate the alveolar bone density. Tartrate-resistant acidic phosphatase staining was used to observe the osteoclast number, alveolar bone, and periodontal tissue. ResultsHA alone did not significantly affect orthodontic tooth movement, alveolar structure density, or periodontal tissue remodeling (P > 0.05). HA combined with a low-energy laser accelerated orthodontic tooth movement. The number of bone absorption lacunae and osteoclasts on the alveolar bone's pressure side increased significantly (P < 0.05), while the density decreased significantly (P < 0.05); however, no root absorption was observed. ConclusionHA can improve the conversion rate of low-energy lasers, enhance the low-energy laser effect, and promote orthodontic tooth movement and periodontal tissue reconstruction on the pressure side in rats, without causing root resorption.

Tumor necrosis factor-α enhances the expression of vascular endothelial growth factor in a mouse orthodontic tooth movement model

Background/purposeTooth movement that is achieved using orthodontic mechanical principles relies on bone resorption which takes place on the compression side via osteoclasts. Tumor necrosis factor-α (TNF-α) has been known to affect osteoclast formation in orthodontic tooth movement (OTM). Vascular endothelial growth factor (VEGF), which is one of the mediators of angiogenesis, also plays an important role in OTM by inducing vascular permeability and chemotaxis of osteoclast precursors. Therefore, the purpose of this research was to evaluate the effect of TNF-α on VEGF expression during OTM. Materials and methodsIn order to demonstrate the effect of TNF-α on VEGF expression during OTM, a nickel titanium closed coil spring was fixed to the upper left first molar and the alveolar bone beneath the upper incisors of both wild type (WT) and TNF receptors (TNFRs) deficient mice resulting in a mesial movement of the molar for 12 days. The maxilla was removed for histological analysis and real-time RCR analysis of VEGF expression. ResultsImmunohistochemical analysis revealed that there were fewer VEGF-positive cells in the periodontal membrane on the mesial side of the distobuccal root in TNFRs-deficient mice than that in WT mice during the OTM for 12 days. Furthermore, expression of VEGF mRNA is lower level in TNFRs-deficient mice than that in WT mice. ConclusionOur results indicate that TNF-α plays an important role in VEGF expression during tooth movement.

Runx1/miR-26a/Jagged1 signaling axis controls osteoclastogenesis and alleviates orthodontically induced inflammatory root resorption

BackgroundMicroRNAs (miRNAs) are involved in the regulation of osteoclast biology and several pathogenic progression. This study aimed to identify the role of miR-26a in osteoclastogenesis and orthodontically induced inflammatory root resorption(OIIRR). MethodsRat orthodontic tooth movement (OTM) model was established by ligating a closed coil spring between maxillary first molar and incisor, and 50 g orthodontic force was applied to move upper first molar to middle for 7 days. Human periodontal ligament (hPDL) cells were isolated from periodontium of healthy donors, and then subjected to compression force (CF) for 24 h to mimic an in vitro OTM model. The levels of associated factors in vivo and in vitro were measured subsequently. ResultThe distance of tooth movement was increased and root resorption pits were occurred in rat OTM model. The expression of miR-26a was decreased in vivo and vitro experiments. CF treatment enhanced the secretion of inflammatory factors receptor activator of nuclear factor-kappa B ligand (RANKL) and IL-6, osteoclast marker levels, and the number of tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts, while miR-26a overexpression reversed these results. Furthermore, miR-26a overexpression inhibited the osteoclastogenesis and rescued the root resorption in OTM rats through inhibition of Jagged1. Additionally, Runx1 could bind to miR-26a promoter and promote its expression, thereby suppressing the osteoclastogenesis. ConclusionWe concluded that Runx1/miR-26a/Jagged1 signaling axis restrained osteoclastogenesis and alleviated OIIRR.

Cigarette Smoke Exposure Inhibits Osteoclast Apoptosis via the mtROS Pathway

It is widely known that smoking is a risk factor for bone loss and plays a key role in osteopenia. Despite this well-known association, the mechanisms by which smoking affects bone have not been definitively established. Since smoking increases bone loss and potentially affects bone resorption in response to mechanical force, we investigated the impact of cigarette smoke on osteoclast numbers and underlying mechanisms in a mouse model of orthodontic tooth movement (OTM). The experimental group was exposed to once-daily cigarette smoke while the control group was not, and tooth movement distance and osteoclast numbers were assessed. In addition, the effect of cigarette smoke extract (CSE) on osteoclast precursor proliferation and osteoclast apoptosis was assessed in vitro. We found that cigarette smoke exposure enhanced bone remodeling stimulated by mechanical force and increased osteoclast numbers in vivo. Also, CSE increased the number of osteoclasts by inhibiting osteoclast apoptosis via the mitochondrial reactive oxygen species/cytochrome C/caspase 3 pathway in vitro. Moreover, exposure of mice to cigarette smoke affected bone marrow cells, leading to increased formation of osteoclasts in vitro. This study identifies a previously unknown mechanism of how smoking has a detrimental impact on bone.

Osteoclastic effects of mBMMSCs under compressive pressure during orthodontic tooth movement

BackgroundDuring orthodontic tooth movement (OTM), alveolar bone remodelling is closely related to mechanical force. It is unclear whether stem cells can affect osteoclastogenesis to promote OTM. This study aimed to investigate the role of mouse bone marrow mesenchymal stem cells (mBMMSCs) under compression load in OTM.MethodsA mouse OTM model was established, and GFP-labelled mBMMSCs and normal saline were injected into different groups of mice by tail vein injection. OTM distance was measured using tissue specimens and micro-computed tomography (micro-CT). The locations of mBMMSCs were traced using GFP immunohistochemistry. Haematoxylin-eosin staining, tartrate-resistant acid phosphate (TRAP) staining and immunohistochemistry of Runx2 and lipoprotein lipase were used to assess changes in the periodontal ligament during OTM. mBMMSCs under compression were co-cultured with mouse bone marrow-derived macrophages (mBMMs), and the gene expression levels of Rankl, Mmp-9, TRAP, Ctsk, Alp, Runx2, Ocn and Osterix were determined by RT-PCR.ResultsTen days after mBMMSCs were injected into the tail vein of mice, the OTM distance increased from 176 (normal saline) to 298.4 μm, as determined by tissue specimen observation, and 174.2 to 302.6 μm, as determined by micro-CT metrological analysis. GFP-labelled mBMMSCs were mostly located on the compressed side of the periodontal ligament. Compared to the saline group, the number of osteoclasts in the alveolar bone increased significantly (P < 0.01) on the compressed side in the mBMMSC group. Three days after mBMMSC injection, the number of Runx2-GFP double-positive cells on the tension side was significantly higher than that on the compression side. After applying compressive force on the mBMMSCs in vitro for 2 days, RANKL expression was significantly higher than in the non-compression cells, but expression of Alp, Runx2, Ocn and Osterix was significantly decreased (P < 0.05). The numbers of osteoclasts differentiated in response to mBMMs co-cultured with mBMMSCs under pressure load and expression of osteoclast differentiation marker genes (Mmp-9, TRAP and Ctsk) were significantly higher than those in mBMMs stimulated by M-CSF alone (P < 0.05).ConclusionsmBMMSCs are not only recruited to the compressed side of the periodontal ligament but can also promote osteoclastogenesis by expressing Rankl, improving the efficiency of OTM.

The effect of bifidobacterium probiotic on heat shock protein-70 expression and osteoclast number during orthodontic tooth movement in rats (Rattus novergicus)

Heat shock protein (HSP)-70 expressed in the fibroblast of periodontal ligament after orthodontic tooth movement (OTM) was applied. Bifidobacterium probiotics regulate the number of osteoclasts through controlling the inflammation via Nuclear Factor Kappa Beta (NFKB) and increased cytoprotection by HSP induction. This study aimed to examine the effect of Bifidobacterium probiotic on HSP-70 expression and osteoclast number during OTM in the compression side of Wistar rats (Rattus novergicus). This research was a true experimental study which used post-test only group design. 42-healthy-Wistar rats (R. novergicus) were blind randomly divided into 6 groups; K1: OTM for 3 days; K2: OTM for 7 days; K3: OTM for 14 days; KP1: OTM and administration of Bifidobacterium probiotic for 3 days; KP2: OTM and administration of Bifidobacterium probiotic for 7 days; KP3: OTM and administration of Bifidobacterium probiotic for 14 days. OTM model was made by installed closed-coil spring with 10g/mm2 force. Bifidobacterium probiotic was orally administered with 10mL/day by means of oral gavage at 1.5 x 108 CFU/mL dose every day. Immunohistochemical analyses were performed in all study groups. One-way ANOVA and LSD test (p<0.05) were performed to compare between groups. The highest HSP-70 expression was discovered in K3 control group and the greatest osteoclast number was found in KP1 control group. The lowest HSP-70 expression and osteoclast number were found in KP3 group with significant between groups. Bifidobacterium probiotic decreased the expression of HSP-70 and osteoclast number during the orthodontic tooth movement in 14 days in the compression side.

Role and Regulation of Mechanotransductive HIF-1α Stabilisation in Periodontal Ligament Fibroblasts.

Orthodontic tooth movement (OTM) creates compressive and tensile strain in the periodontal ligament, causing circulation disorders. Hypoxia-inducible factor 1α (HIF-1α) has been shown to be primarily stabilised by compression, but not hypoxia in periodontal ligament fibroblasts (PDLF) during mechanical strain, which are key regulators of OTM. This study aimed to elucidate the role of heparan sulfate integrin interaction and downstream kinase phosphorylation for HIF-1α stabilisation under compressive and tensile strain and to which extent downstream synthesis of VEGF and prostaglandins is HIF-1α-dependent in a model of simulated OTM in PDLF. PDLF were subjected to compressive or tensile strain for 48 h. In various setups HIF-1α was experimentally stabilised (DMOG) or destabilised (YC-1) and mechanotransduction was inhibited by surfen and genistein. We found that HIF-1α was not stabilised by tensile, but rather by compressive strain. HIF-1α stabilisation had an inductive effect on prostaglandin and VEGF synthesis. As expected, HIF-1α destabilisation reduced VEGF expression, whereas prostaglandin synthesis was increased. Inhibition of integrin mechanotransduction via surfen or genistein prevented stabilisation of HIF-1α. A decrease in VEGF expression was observed, but not in prostaglandin synthesis. Stabilisation of HIF-1α via integrin mechanotransduction and downstream phosphorylation of kinases seems to be essential for the induction of VEGF, but not prostaglandin synthesis by PDLF during compressive (but not tensile) orthodontic strain.

Local delivery of simvastatin maintains tooth anchorage during mechanical tooth moving via anti-inflammation property and AMPK/MAPK/NF-kB inhibition.

Simvastatin (SMV) could increase tooth anchorage during orthodontic tooth movement (OTM). However, previous studies on its bone‐specific anabolic and anti‐inflammation properties were based on static in vitro and in vivo conditions. AMPK is a stress‐activated kinase that protects tissue against serious damage from overloading inflammation. Rat periodontal ligament cells (PDLCs) were subjected to a serial of SMV concentrations to investigate the optimization that promoted osteogenic differentiation. The PDLCs in static and/or tensile culturing conditions then received the proper concentration SMV. Related factors expression was measured by the protein array, real‐time PCR and Western blot. The 0.05UM SMV triggered osteogenic differentiation of PDLCs. The inhibition of AMPK activation through a pharmacological approach (Compound C) caused dramatic decrease in osteogenic/angiogenic gene expression and significant increase in inflammatory NF‐κB phosphorylation. In contrast, pharmacological activation of AMPK by AICAR significantly inhibited inflammatory factors expression and activated ERK1/2, P38 MAPK phosphorylation. Moreover, AMPK activation induced by SMV delivery significantly attenuated the osteoclastogenesis and decreased the expression of pro‐inflammatory TNF‐α and NF‐κB in a rodent model of OTM. The current studies suggested that SMV could intrigue intrinsic activation of AMPK in PDLCs that promote attenuate the inflammation which occurred under tensile irritation through AMPK/MAPK/NF‐kB Inhibition.

Parathyroid hormone increases alveolar bone homoeostasis during orthodontic tooth movement in rats with periodontitis via crosstalk between STAT3 and \u03b2-catenin

Periodontitis patients are at risk of alveolar bone loss during orthodontic treatment. The aim of this study was to investigate whether intermittent parathyroid hormone (1–34) treatment (iPTH) could reduce alveolar bone loss during orthodontic tooth movement (OTM) in individuals with periodontitis and the underlying mechanism. A rat model of OTM in the context of periodontitis was established and alveolar bone loss was observed. The control, iPTH and iPTH + stattic groups received injections of vehicle, PTH and vehicle, or PTH and the signal transducer and activator of transcription 3 (STAT3) inhibitor stattic, respectively. iPTH prevented alveolar bone loss by enhancing osteogenesis and suppressing bone resorption in the alveolar bone during OTM in rats with periodontitis. This effect of iPTH was along with STAT3 activation and reduced by a local injection of stattic. iPTH promoted osteoblastic differentiation and might further regulate the Wnt/β-catenin pathway in a STAT3-dependent manner. The findings of this study suggest that iPTH might reduce alveolar bone loss during OTM in rats with periodontitis through STAT3/β-catenin crosstalk.

LncRNA TUG1 positively regulates osteoclast differentiation by targeting v-maf musculoaponeurotic fibrosarcoma oncogene homolog B

Osteoclast differentiation-mediates bone resorption is the key biological basis of orthodontic treatment while the specific mechanism of osteoclastogenesis remains unclear. This study aims to explore the underlying mechanism of the osteoclast differentiation from the perspective of long non-coding RNA (LncRNA). In the present study, the osteoclast differentiation of CD14+ peripheral blood mononuclear cells (PBMCs) was induced by recombinant human macrophage colony-stimulating factor (M-CSF) and receptor activator of nuclear factor κB ligand (RANKL), and LncRNA TUG1 expression was dramatically elevated during this process. Functionally, the silence of TUG1 in CD14+ PBMCs decreased tartrate-resistant acid phosphatase (TRAP)-positive cell numbers and the protein levels of TRAP, nuclear factor of activated T cell c1 (NFATc1), and osteoclast-associated receptor (OSCAR), whereas increased V‐maf musculoaponeurotic fibrosarcoma oncogene homolog B (MafB) protein level. The subsequent experiments confirmed that TUG1 lessened the MafB protein level via accelerating its degradation. Then, the interference of MafB reversed the inhibitory effect of si-TUG1 on osteoclastogenesis, including increased the TRAP-positive cell numbers and up-regulated the protein levels of osteoclast markers. Finally, the in vivo experiments displayed that the increased TUG1 levels could promote tooth movement and bone resorption via facilitating osteoclast differentiation in the rat model of orthodontic tooth movement. In summary, TUG1 overexpressed during the process of osteoclast differentiation and positively regulated osteoclast differentiation by targeting MafB.