Expression of hypoxia-inducible factor-1α in periodontal tissues during orthodontic tooth movement

目的 观察正畸牙移动过程中低氧诱导因子-1α(HIF-1α)在牙周组织内的表达分布情况,探讨其与牙周组织改建的关系.方法 30只雄性白兔随机分为不加力对照组和加力1、3、7、14、21天组,每组5只.采用HE和免疫组化法观察检测,并对HIF-1α表达强度进行半定量分析.结果 加力后HIF-1α表达显著增强,7天时达到峰值,14天后逐渐减弱,主要定位于血管内皮细胞,成纤维细胞,成骨细胞和破骨细胞.结论 HIF-1α参与了牙周组织改建并在其中起重要作用.     

The role of psychologic stress-induced hypoxia-inducible factor-1α in rat experimental periodontitis

Background: Studies have shown that psychologic stress plays a significant role in the outcome of many diseases. The present study is designed to investigate the effect of stress on experimental ligature‐induced periodontal disease in rats by means of a variable moderate chronic stress model. Methods: Sixty‐six age‐matched male Wistar rats of specific pathogen‐free grade were randomly divided into four groups: 1) normal control group, naive rats; 2) experimental periodontitis group, received only silk ligatures at the gingival margins of the second maxillary molar; 3) stress‐stimulation group, treated only with experimental stress conditions; and 4) experimental periodontitis plus stress‐stimulation group (e.g., experimental groups also exposed to stress). Stress was imposed by means of restraint stress, cold‐water immersion stress, and cat shock stress, which were all applied randomly. The rats were sacrificed at weeks 1, 4, 6, and 8 of the experiment. Attachment losses (AL) were measured by a specially made periodontal probe. The histopathologic changes of periodontia stained with hematoxylin and eosin were observed under a microscope. The expression of hypoxia‐inducible factor‐1α used to evaluate tissue hypoxic degree in periodontal tissues was tested by immunohistochemistry. Results: Our results show that there was no significant difference of AL among the normal control and the stress‐stimulation groups (P >0.05); AL of the periodontitis plus stress‐stimulation group was significantly higher than that of the experimental periodontitis group at weeks 4, 6, and 8 (P <0.01), and the hypoxia‐inducible factor‐1α expression scores of the periodontitis plus stress‐stimulation group were significantly higher than those of the experimental periodontitis group at weeks 4, 6, and 8 (P = 0.0477). Conclusions: Stress‐stimulation may aggravate periodontitis by decreased tissue oxygenation in rats. We conclude that there is a correlation of periodontitis severity with psychologic stress and periodontal tissue hypoxia.     

Nicotine and lipopolysaccharide stimulate the production of MMPs and prostaglandin E(2) by hypoxia-inducible factor-1α up-regulation in human periodontal ligament cells

Kim Y‐S, Shin S‐I, Kang K‐L, Herr Y, Bae W‐J, Kim E‐C. Nicotine and lipopolysaccharide stimulate the production of MMPs and prostaglandin E₂ by hypoxia‐inducible factor‐1α up‐regulation in human periodontal ligament cells. J Periodont Res 2012; 47: 719–728. © 2012 John Wiley & Sons A/S Background and Objective: Although hypoxia‐inducible factor 1α (HIF‐1α) is up‐regulated in the periodontal pockets of periodontitis patients, the expression and precise molecular mechanisms of HIF‐1α remain unknown in human periodontal ligament cells (PDLCs). The aim of this study was to explore the effects, as well as the signaling pathway, of nicotine and lipopolysaccharide (LPS) on the expression of HIF‐1α and on the production of its target genes, including cyclooxygenase‐2 (COX‐2)‐derived prostaglandin E₂ (PGE₂), MMP‐2 and MMP‐9 in PDLCs. Material and Methods: The expression of COX‐2 and HIF‐1α proteins was evaluated using western blotting. The production of PGE₂ and MMPs was evaluated using enzyme immunoassays and zymography, respectively. Results: LPS and nicotine synergistically induced the production of PGE₂, MMP‐2 and MMP‐9, and increased the expression of MMP‐2, MMP‐9, COX‐2 and HIF‐1α proteins. Inhibition of HIF‐1α activity by chetomin or knockdown of HIF1α gene expression by small interfering RNA markedly attenuated the production of LPS‐ and nicotine‐stimulated PGE₂ and MMPs, as well as the expression of COX‐2 and HIF‐1α. Furthermore, pretreatment with inhibitors of COX‐2, p38, extracellular signal‐regulated kinase, Jun N‐terminal kinase, protein kinase C, phosphatidylinositol 3‐kinase and nuclear factor‐kappaB decreased the expression of nicotine‐ and LPS‐induced HIF‐1α and COX‐2, as well as the activity of PGE₂ and MMPs. Conclusion: These data demonstrate novel mechanisms by which nicotine and LPS promote periodontal tissue destruction, and provide further evidence that HIF‐1α is a potential target in periodontal disease associated with smoking and dental plaque.     

Synergistic induction of periodontal tissue regeneration by binary application of human osteogenic protein-1 and human transforming growth factor-β3 in Class II furcation defects of Papio ursinus

Teare JA, Petit J‐C, Ripamonti U. Synergistic induction of periodontal tissue regeneration by binary application of human osteogenic protein‐1 and human transforming growth factor‐β ₃ in Class II furcation defects of Papio ursinus. J Periodont Res 2012; 47: 336–344. © 2011 John Wiley & Sons A/S Background and Objective: Binary applications of recombinant human osteogenic protein‐1 (hOP‐1) and transforming growth factor‐β3 (hTGF‐β3) synergize to induce pronounced bone formation. To induce periodontal tissue regeneration, binary applications of hOP‐1 and hTGF‐β₃ were implanted in Class II furcation defects of the Chacma baboon, Papio ursinus. Material and Methods: Defects were created bilaterally in the furcation of the first and second mandibular molars of three adult baboons. Single applications of 25 μg hOP‐1 and 75 μg hTGF‐β₃ in Matrigel^® matrix were compared with 20:1 binary applications, i.e. 25 μg hOP‐1 and 1.25 μg hTGF‐β₃. Morcellated fragments of autogenous rectus abdominis striated muscle were added to binary applications. Sixty days after implantation, the animals were killed and the operated tissues harvested en bloc. Undecalcified sections were studied by light microscopy, and regenerated tissue was assessed by measuring volume and height of newly formed alveolar bone and cementum. Results: The hOP‐1 and hTGF‐β₃ induced periodontal tissue regeneration and cementogenesis. Qualitative morphological analysis of binary applications showed clear evidence for considerable periodontal tissue regeneration. Quantitatively, the differences in the histomorphometric values did not reach statistical significance for the group size chosen for this primate study. The addition of morcellated muscle fragments did not enhance tissue regeneration. Binary applications showed rapid expansion of the newly formed bone against the root surfaces following fibrovascular tissue induction in the centre of the treated defects. Conclusion: Binary applications of hOP‐1and hTGF‐β₃ in Matrigel^® matrix in Class II furcation defects of P. ursinus induced substantial periodontal tissue regeneration, which was tempered, however, by the anatomy of the furcation defect model, which does not allow for the rapid growth and expansion of the synergistic induction of bone formation, particularly when additionally treated with responding myoblastic stem cells.     

Participation of hypoxia-inducible factor-1α and lymphangiogenesis in metastatic and non-metastatic lower lip squamous cell carcinoma

This study evaluated the lymphatic density and HIF-1α immunoexpression in lower lip squamous cell carcinoma (LLSCC) and their correlation with clinicopathological (nodal metastasis, clinical stage, histological grade, recurrence and disease outcome) and survival parameters in 20 metastatic and 20 non-metastatic LLSCCs. Lymphatic density was established by counting microvessels (D2-40⁺) at the tumor core (intratumoral lymphatic density, ILD) and at the invasive front (peritumoral lymphatic density, PLD) and percentages of immunopositive cells for HIF-1α were established. No statistically significant differences in lymphatic densities in relation to clinicopathological parameters were observed (P > 0.05). All cases exhibited nuclear and cytoplasmic HIF-1α immunoexpression, with relatively high percentages of positivity, but this expression was not statistically different in relation to clinicopathological variables (P > 0.05). Positive correlations were observed between ILD and PLD (P = 0.002), and between nuclear HIF-1α immunoexpression at the tumor core and ILD (P = 0.001). The results suggest ILD and PLD are not directly related to the development of lymph node metastasis in LLSCC. The striking expression of HIF-1α suggests the involvement of this protein in the etiopathogenesis of LLSCCs, possibly stimulating lymphangiogenesis at the tumor core. However, this protein does not seem to exert a determining influence on the biological aggressiveness of these tumors.     

Serum plasminogen activator inhibitor-1 and tumor necrosis factor-α levels in obesity and periodontal disease

Background: Several studies have shown a possible association between periodontal disease and obesity. The aim of this study is to evaluate serum plasminogen activator inhibitor 1 (PAI‐1), tumor necrosis factor‐alpha (TNF‐α), and high‐sensitivity C‐reactive protein (hsCRP) levels in the association between obesity and periodontal disease. Methods: Two hundred individuals participated in this study. Body mass index (BMI), waist‐to‐hip ratio, plasma triglyceride (TRG), total cholesterol, low‐density lipoprotein cholesterol, high‐density lipoprotein cholesterol (HDL‐C), fasting blood glucose (FBG), hsCRP, TNF‐α, PAI‐1, and periodontal parameters (including plaque index [PI], probing depth [PD], clinical attachment level [CAL], and percentage of sites with bleeding on probing) were evaluated. Results: The groups with BMI ≥ 25 had higher median values for FBG, TRG, hsCRP, PAI‐1, PI, and CAL than did the groups with a BMI < 25 (P <0.01). Serum TRG levels were positively correlated with PI, PD, and CAL. There were negative associations between clinical periodontal parameters and HDL‐C. There were statistically significant correlations between PAI‐1 and clinical periodontal parameters (PI, PD, and CAL). Conclusion: Serum PAI‐1 levels may play an important role in the association between periodontal disease and obesity.     

Roles of hypoxia inducible factor-1α in the temporomandibular joint

ObjectiveTemporomandibular joint osteoarthritis (TMJ-OA) is a degenerative disease characterized by permanent cartilage loss. Articular cartilage is maintained in a low-oxygen environment. The chondrocyte response to hypoxic conditions involves expression of hypoxia inducible factor 1α (HIF-1α), which induces chondrocytes to increase expression of vascular endothelial growth factor (VEGF). Here, we investigated the role of HIF-1α in mechanical load effects on condylar cartilage and subchondral bone in heterozygous HIF-1α-deficient mice (HIF-1α^+/−).DesignMechanical stress was applied to the TMJ of C57BL/6NCr wild-type (WT) and HIF-1α^+/− mice with a sliding plate for 10 days. Histological analysis was performed by HE staining, Safranin-O/Fast green staining, and immunostaining specific for articular cartilage homeostasis.ResultsHIF-1α^+/− mice had thinner cartilage and smaller areas of proteoglycan than WT controls, without and with mechanical stress. Mechanical stress resulted in prominent degenerative changes with increased expression of HIF-1α, VEGF, and the apoptosis factor cleaved Caspase-3 in condylar cartilage.ConclusionOur results indicate that HIF-1α may be important for articular cartilage homeostasis and protective against articular cartilage degradation in the TMJ under mechanical stress condition, therefore HIF-1α could be an important new therapeutic target in TMJ-OA.     

Effect of β tricalcium phosphate particle size on recombinant human platelet-derived growth factor-BB-induced regeneration of periodontal tissue in dog

The aim of this study was to investigate the effect of β tricalcium phosphate (β-TCP) particle size on recombinant human platelet-derived growth factor-BB (rhPDGF-BB)-induced regeneration of periodontal tissue in dog. The control group (rhPDGF-BB alone) was characterized by incomplete, newly formed bone. The large-particle β-TCP (L-TCP(O))/rhPDGF-BB group showed a statistically significant increase in both new bone and cementum formation compared to the small-particle β-TCP (S-TCP(G))/rhPDGF-BB group. These findings suggest that L-TCP(O)-particle promotes rhPDGF-BB-induced formation of bone and cementum.     

Differential Expression of HIF-1α in Skin and Mucosal Wounds

Despite accelerated epithelial closure, oral mucosal wounds exhibit lower levels of VEGF and a more refined angiogenic response than do skin wounds. The specific differences in angiogenesis suggest that skin and oral mucosal wounds may experience dissimilar levels of hypoxia and HIF-1α. Using a model of comparable wounds on murine dorsal skin and tongue, we determined levels of hypoxia and HIF-1α. Skin wounds were found to be significantly more hypoxic and had higher levels of HIF-1α than mucosal wounds. Furthermore, under stressed conditions, skin wounds, but not mucosal wounds, exhibited a further elevation of HIF-1α beyond that of non-stressed levels. To determine if manipulation of oxygen levels might equalize the repair response of each tissue, we exposed mice to hyperbaric oxygen treatment (HBOT) following wounding. HBOT did not significantly change HIF-1α or VEGF expression in either skin or mucosal wounds, nor did it alter wound bed vascularity. These studies suggest that skin wounds have higher levels of hypoxia than do mucosal wounds, along with a differential expression of HIF-1α. Interestingly, modulation of oxygen by HBOT does not ameliorate this difference. These results suggest that differential responses to hypoxia may underlie the distinctive wound-healing phenotypes seen in skin and oral mucosa.     

Hypoxia enhances the effect of lipopolysaccharide-stimulated IL-1β expression in human periodontal ligament cells

Oral infection is inflammatory disease caused by bacteria. A major component of gram negative bacteria membrane associated with inflammation is lipopolysaccharide (LPS). Currently, evidence presenting the combined effect of LPS and hypoxia to inflammatory response in human periodontal ligament cells (HPDLs) was yet lacking. Here, we studied whether the influence of oxygen on LPS-stimulated inflammatory cytokines in HPDLs. HPDLs were stimulated with LPS in normoxia and hypoxia for 24 h. The mRNA and protein expression of inflammatory cytokines were examined by polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. The intracellular mechanisms of these effects were investigated by chemical inhibitors and small interfering RNA (siRNA). The results showed that LPS-stimulated IL-1β, IL-6, IL-8 in HPDLs in both hypoxia and normoxia. Hypoxia condition enhanced the effect of LPS-stimulated cytokines expression. Apigenin, the hypoxia-inducible factors (HIF)-1α inhibitor, totally prevented LPS-stimulated IL-1β expression in both normoxia and hypoxia. Similar to knockout HIF-1α gene expression by siRNA did \not prevent LPS-stimulated IL-1β expression. These data concluded that hypoxia increased virulence of LPS-stimulated IL-1β production in HPDLs.     

MAPKs, activator protein-1 and nuclear factor-κB mediate production of interleukin-1β-stimulated cytokines, prostaglandin E₂ and MMP-1 in human periodontal ligament cells

Murayama R, Kobayashi M, Takeshita A, Yasui T, Yamamoto M. MAPKs, activator protein‐1 and nuclear factor‐κB mediate production of interleukin‐1β‐stimulated cytokines, prostaglandin E ₂ and MMP‐1 in human periodontal ligament cells. J Periodont Res 2011; 46: 568–575. © 2011 John Wiley & Sons A/S Background and Objective: Determination of the interleukin‐1 (IL‐1) signaling cascades that lead to the production of various inflammatory mediators and catabolic factors may clarify attractive targets for therapeutic intervention for periodontitis. We comprehensively assessed the involvement of MAPKs, activator protein‐1 (AP‐1) and nuclear factor‐κB (NF‐κB) in IL‐1β‐induced production of interleukin‐6 (IL‐6), interleukin‐8 (IL‐8), prostaglandin E₂ (PGE₂) and MMP‐1 in human periodontal ligament cells. Material and Methods: Human periodontal ligament cells were pretreated with an inhibitor for each of the MAPKs or NF‐κB and subsequently treated with IL‐1β. Following treatment, phosphorylation of three types of MAPK (ERK, p38 MAPK and c‐Jun N‐terminal kinase), IκB kinase (IKK) α/β/γ and IκB‐α, as well as the DNA binding activity of AP‐1 and NF‐κB and the production of IL‐6, IL‐8, PGE₂ and MMP‐1, were determined by western blotting, a gel mobility shift assay and ELISA, respectively. Results: The three MAPKs, simultaneously activated by IL‐1β, mediated the subsequent DNA binding of AP‐1 at various magnitudes, while IKKα/β/γ, IκB‐α and NF‐κB were also involved in the IL‐1 signaling cascade. Furthermore, IL‐1β stimulated the production of IL‐6, IL‐8, PGE₂ and MMP‐1 via activation of the three MAPKs and NF‐κB, because inhibitors of these significantly suppressed the IL‐1β‐stimulated production of these factors. Conclusion: Our results strongly suggest that MAPK, AP‐1 and NF‐κB mediate the IL‐1β‐stimulated synthesis of IL‐6, IL‐8, PGE₂ and MMP‐1 in human periodontal ligament cells. Therefore, inhibition of activation of MAPK, AP‐1 and/or NF‐κB may lead to therapeutic effects on progression of periodontitis.     

Decreased TNF-α gene expression in periodontal ligature in MSG-obese rats: A possible protective effect of hypothalamic obesity against periodontal disease?

The prevalence of obesity is increasing globally. There is evidence that the uncontrolled energetic metabolism in obese patients can accelerate periodontal disease. Therefore, the aim of this study was evaluate the possible relationship between hypothalamic obesity induced by neonatal treatment with MSG and experimental periodontal disease. Newborn male Wistar rats received subcutaneous injections in the cervical region, of 4g/Kg/day of body weight (BW) of MSG (MSG group) or hypertonic saline solution, 1.25/kg/day BW (control group, CTL). At 70 days of life periodontal disease was induced in these animals. After they were sacrificed, radiographic analyses of alveolar bone resorption and Tumor Necrosis Factor α (TNFα) gene expression in gingival tissue were performed. The neonatal treatment with MSG did not affect the concentration of plasma glucose and cholesterol (CHOL). However, plasma insulin, non-esterified fatty acids (NEFA) and triglycerides (TG) leves were higher in MSG compared with CTL group. The alveolar bone resorption was 44% lower in MSG-obese rats compared with CTL rats. In the presence of periodontal ligature, there was an increase in this parameter in all groups. The TNFα gene expression, an inflammatory marker, in periodontal tissue was similar in obese and CTL rats. The presence of ligature increased TNFα gene expression in both groups, but in a lower extension in MSG-obese rats. In conclusion these results suggested that hypothalamic obesity may produce a protective effect against periodontal disease, however further research is needed to understand the mechanisms involved in this process.     

Donor–host tissue interaction in allogenic transplanted tooth germ with special reference to periodontal tissue

Objectives

Limited biological evidence exists regarding donor–host interaction in the periodontal tissue during allogenic tooth germ transplantation. This study aimed to clarify donor–host tissue interactions during periodontal tissue healing following tooth germ transplantation.

Expression of NaV-1.7, TNF-α and HSP-70 in experimental flare-up post-extirpated dental pulp tissue through a neuroimmunological approach

BackgroundDental caries continue to represent a major problem which, if left untreated, will cause irreversible pulpitis. Root canal treatment constitutes one potential treatment intended to preserve teeth afflicted with irreversible pulpitis. During root canal treatment, pain or swelling, referred to as flare-ups, can occur at any point in the process.AimTo analyze the molecular aspect of the phenomenon of flare-up in vital dental pulp tissue following mechanical and bacterial trauma (extirpation and lipopolysaccharide [LPS] induction respectively) through a neurological approach, based on the expression of NaV-1.7 in neuron cells, and HSP-70, TNF-α in macrophage cells.MethodThis laboratory experimental study was conducted using 15 Spraque Dawley rats as subjects which were divided into three groups of five subjects: a control group, a pulp tissue extirpation group and an LPS induction followed by extirpation of pulp tissue group. Test samples were collected from the apical field of the mandibular incisor and subsequently examined using immunohistochemical methods.ResultsThere were significant differences in NaV1.7, HSP70 and TNFα expression between the treatment groups. While a marked increase in the expression of HSP70 occurred, both Nav1.7, and TNFα expression decreased significantly.ConclusionExtirpating the dental pulp tissue will induce a more pronounced flare-up response from the molecules of the pulp tissue in vital teeth than those in inflamed vital pulp tissue.