Toll‐like receptors 2 and 5 in human gingival epithelial cells co‐operate with T‐cell cytokine interleukin‐17

Background/aim: Periodontitis begins as the result of perturbation of the gingival epithelial cells caused by subgingival bacteria interacting with the epithelial cells via pattern recognition receptors. Toll‐like receptors (TLRs) have been shown to play an important role in the recognition of periodontal pathogens so we have studied the interaction of TLR ligands with TLR2 and TLR5 for cytokine production in the cultures of gingival epithelial cells. Methods: Immunohistochemistry was used for the localization of TLR2 and TLR5 in tissue specimens. Enzyme‐linked immunosorbent assays were performed to detect the levels of interleukin‐1β (IL‐1β) and tumor necrosis factor‐α (TNF‐α), released from gingival epithelial cell cultures following stimulation with TLR ligand alone or in combination with IL‐17. Results: Both TLR2 and TLR5 were increased in periodontitis (2128 ± 159 vs. 449 ± 59 and 2456 ± 297 vs. 679 ± 103, respectively, P < 0.001) including gingival epithelial cells that stained strongly. Cultured gingival epithelial cells stimulated with their respective ligands (HKLM, a TLR2 ligand that is also found in Porphyromonas gingivalis, and flagellin, a TLR5 ligand that is also found in Treponema denticola) produced both IL‐1β and TNF‐α. To mimic T‐cell help, IL‐17 was added. This further greatly enhanced TLR ligand‐induced IL‐1β (P < 0.001) and TNF‐α (P < 0.01) production. Conclusions: These findings show how pathogen‐associated molecular patterns, shared by many different periodontopathogenic bacteria, stimulate the resident gingival epithelial cells to inflammatory responses in a TLR‐dependent manner. This stimulation may be particularly strong in periodontitis and when T helper type 17 cells provide T‐cell help in intercellular cooperation.     

Enamel matrix derivative induces production of vascular endothelial cell growth factor in human gingival fibroblasts

Enamel matrix derivative (EMD) may enhance periodontal wound healing by inducing angiogenesis. We sought to investigate the effect and the mechanism of action of EMD on vascular endothelial growth factor (VEGF) production by human gingival fibroblasts. Cells were stimulated with EMD, transforming growth factor‐β1 (TGF‐β1), or fibroblast growth factor 2 (FGF‐2), with or without antibodies to TGF‐β1 or FGF‐2. The levels of VEGF in the culture media were measured using an ELISA. We examined the effects of SB203580 [a p38 mitogen‐activated protein kinase (MAPK) inhibitor], U0126 [an extracellular signal‐regulated kinase (ERK) inhibitor], SP600125 [a c‐Jun N‐terminal kinase (JNK) inhibitor], and LY294002 [a phosphatidylinositol 3‐kinase (PI3K)/Akt inhibitor] on EMD‐induced VEGF production. Enamel matrix derivative stimulated the production of VEGF in a dose‐ and time‐dependent manner. Treatment of human gingival fibroblasts with antibodies to TGF‐β1 or FGF‐2 significantly decreased EMD‐induced VEGF production, whereas the addition of exogenous TGF‐β1 and FGF‐2 stimulated VEGF production. Enamel matrix derivative‐induced VEGF production was significantly attenuated by SB203580, U0126, and LY294002. Our results suggest that EMD stimulates VEGF production partially via TGF‐β1 and FGF‐2 in human gingival fibroblasts and that EMD‐induced VEGF production is regulated by ERK, p38 MAPK, and PI3K/Akt pathways. Enamel matrix derivative‐induced production of VEGF by human gingival fibroblasts may be involved in the enhancement of periodontal wound healing by inducing angiogenesis.     

In vivo expression of Toll‐like receptor 2, Toll‐like receptor 4, CSF2 and LY64 in Chinese chronic periodontitis patients

Oral Diseases (2010) 16 , 343–350 Objective: Toll‐like receptors (TLRs) are the essential components in the innate and adaptive immune systems. Colony stimulating factor 2 (CSF2) is a cytokine that may prevent endotoxin tolerance, and LY64 has the ability to interfere with the recognition of bacteria via TLR4. The aim of this study was to explore the in vivo expressions of TLR2, TLR4, CSF2 and LY64 in Chinese chronic periodontitis patients. Methods: Gingival biopsies were collected from 24 chronic periodontitis patients and 19 healthy controls. The gene expression profiles of TLR2, TLR4, CSF2 and LY64 were investigated by real‐time polymerase chain reaction, and the protein expressions of TLR2 and TLR4 were detected by immunohistochemistry. In addition, the levels of CSF2 in gingival crevicular fluid (GCF) were determined by ELISA. Results: The higher mRNA expressions of TLR2, TLR4 and CSF2, and the lower mRNA expression of LY64 were detected in chronic periodontitis patients. And the increased protein expressions of TLR2 and TLR4 were confirmed by immunohistochemistry. In addition, the increase of total amount of CSF2 in GCF was observed in chronic periodontitis patients. Conclusions: Our results suggest that TLR2 and TLR4 may play a role in periodontal pathogenesis. In addition, CSF2 and LY64 may contribute to the regulation of inflammatory response and maintaining periodontal homeostasis.     

Nitric oxide inhibits androgen receptor-mediated collagen production in human gingival fibroblasts

Lin S‐J, Lu H‐K, Lee H‐W, Chen Y‐C, Li C‐L, Wang L‐F. Nitric oxide inhibits androgen receptor‐mediated collagen production in human gingival fibroblasts. J Periodont Res 2012; 47: 701–710. © 2012 John Wiley & Sons A/S Background and Objective: In our previous study, we found that flutamide [an androgen receptor (AR) antagonist] inhibited the up‐regulation of collagen induced by interleukin (IL)‐1β and/or nifedipine in gingival fibroblasts. The present study attempted to verify the role of nitric oxide (NO) in the IL‐1β/nifedipine‐AR pathway in gingival overgrowth. Material and Methods: Confluent gingival fibroblasts derived from healthy individuals (n = 4) and those with dihydropyridine‐induced gingival overgrowth (DIGO) (n = 6) were stimulated for 48 h with IL‐1β (10 ng/mL), nifedipine (0.34 μm ) or IL‐1β + nifedipine. Gene and protein expression were analyzed with real‐time RT‐PCR and western blot analyses, respectively. Meanwhile, Sircol dye‐binding and the Griess reagent were, respectively, used to detect the concentrations of total soluble collagen and nitrite in the medium. Results: IL‐1β and nifedipine simultaneously up‐regulated the expression of the AR and type‐I collagen α1 [Colα1(I)] genes and the total collagen concentration in DIGO cells (p < 0.05). IL‐1β strongly increased the expression of inducible nitric oxide synthase (iNOS) mRNA and the nitrite concentration in both healthy and DIGO cells (p < 0.05). However, co‐administration of IL‐1β and nifedipine largely abrogated the expression of iNOS mRNA and the nitrite concentration with the same treatment. Spearman’s correlation coefficients revealed a positive correlation between the AR and total collagen (p < 0.001), but they both showed a negative correlation with iNOS expression and the NO concentration (p < 0.001). The iNOS inhibitor, 1400W, enhanced IL‐1β‐induced AR expression; furthermore, the NO donor, NONOate, diminished the expression of the AR to a similar extent in gingival fibroblasts derived from both healthy patients and DIGO patients (p < 0.05). Conclusion: IL‐1β‐induced NO attenuated AR‐mediated collagen production in human gingival fibroblasts. The iNOS/NO system down‐regulated the axis of AR/Colα1(I) mRNA expression and the production of AR/total collagen proteins by DIGO cells.     

血管内皮生长因子在正常与牙周炎牙龈组织中的表达差异研究

目的 检测血管内皮生长因子(VEGF)在正常与牙周炎的牙龈组织中的表达差异。方法 采用免疫组化PV两步法,检测VEGF在20例健康成人与20例慢性中重度牙周炎患者的牙龈组织中的表达差异。结果 健康组牙龈组织VEGF表达局限于上皮的颗粒层与部分棘层,其下方的结缔组织呈弱阳性表达,实验组牙龈组织上皮全层及结缔组织均呈强阳性表达,实验组VEGF表达高于健康组,两组之间的差异具有统计学意义(上皮区P<0.01,结缔组织区P<0.05)。结论 VEGF可能参与了牙周炎牙周袋壁龈组织的病理改变过程,在牙周炎发生发展及修复机制中可能具有重要意义。     

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.     

Prolyl hydroxylase inhibitors increase the production of vascular endothelial growth factor by periodontal fibroblasts

Agis H, Watzek G, Gruber R. Prolyl hydroxylase inhibitors increase the production of vascular endothelial growth factor by periodontal fibroblasts. J Periodont Res 2012; 47: 165–173. © 2011 John Wiley & Sons A/S Background and Objective: Pharmacological inhibitors of prolyl hydroxylases (PHDs) can induce a proangiogenic response that favors wound healing and bone regeneration. However, the response of periodontal cells to PHD inhibitors is unknown. Material and Methods: To determine the effects of PHD inhibitors on periodontal cells, we exposed human fibroblasts from the gingiva and the periodontal ligament to dimethyloxallyl glycine, desferrioxamine, l ‐mimosine and CoCl₂. Viability, proliferation, and protein synthesis were assessed by 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT), [³H]thymidine, and [³H]leucine incorporation, respectively. The levels of Ki67, hypoxia‐inducible factor 1α (HIF‐1α), p27, phosphorylated c‐Jun N‐terminal kinase (JNK) and phosphorylated p38 were determined by immunohistochemistry and western blotting. Vascular endothelial growth factor (VEGF) mRNA levels were measured by quantitative PCR. Protein levels of VEGF and interleukin (IL)‐6 were evaluated by immunoassays. Results: We found that PHD inhibitors, while leaving cell viability unchanged, reduced proliferation and protein synthesis. This was paralleled by decreased Ki67 levels and increased p27 levels, suggesting that PHD inhibitors provoke growth arrest. Independently from this response, PHD inhibitors stabilized HIF‐1α and increased the production of VEGF. This increase of VEGF was observed in the presence of proinflammatory IL‐1 and pharmacological inhibitors of JNK and p38 signaling. Moreover, PHD inhibitors did not modulate expression of IL‐6 and the phosphorylation of JNK and p38. Conclusion: These results suggest that PHD inhibitors enhance the production of VEGF in periodontal fibroblasts, even in the presence of proinflammatory IL‐1. The data further suggest that PHD inhibitors do not provoke a significant proinflammatory or anti‐inflammatory response in this in vitro setting.     

Peptides of human gingival crevicular fluid determined by HPLC-ESI-MS

The acidic-soluble protein content of human gingival crevicular fluid was analyzed by reverse-phase high-performance liquid chromatography (RP-HPLC), and the eluent deriving from the chromatography separation was directly introduced into an ion-trap mass spectrometer through electrospray ionization (ESI-IT MS). By this technique the molecular weight of peptides/proteins was determined with a precision of approximately 1/10,000 amu. On the basis of the chromatographic behavior and the knowledge of the molecular mass value, some peptides and proteins soluble in acidic solution were unambiguously recognized. Besides high quantities of human serum albumin, alpha-defensins 1-4 and minor amounts of cystatin A, statherin, basic PB salivary peptide and other unidentified components were detected. The presence of alpha-defensins in gingival crevicular fluid is in agreement with their relevant contribution to protein composition deriving from granulocyte secretions. Other peptides and proteins abundant in human saliva, such as proline-rich proteins (PRPs) and histatins, were not detected in gingival crevicular fluid. Further investigations will be necessary to establish the origin of statherin and PB salivary peptide in gingival crevicular fluid.     

Molecular events associated with ciclosporin A-induced gingival overgrowth are attenuated by Smad7 overexpression in fibroblasts

Sobral LM, Aseredo F, Agostini M, Bufalino A, Pereira MCC, Graner E, Coletta RD. Molecular events associated with ciclosporin A‐induced gingival overgrowth are attenuated by Smad7 overexpression in fibroblasts. J Periodont Res 2012; 47: 149–158. © 2011 John Wiley & Sons A/S Background and Objective: Ciclosporin A (CsA)‐induced gingival overgrowth is attributed to an exaggerated accumulation of extracellular matrix, which is mainly due to an increased expression of transforming growth factor‐β1 (TGF‐β1). Herein, the in vitro investigation of effects of overexpression of Smad7, a TGF‐β1 signaling inhibitor, in the events associated with CsA‐induced extracellular matrix accumulation was performed. Material and Methods: The effects of Smad7 were assessed by stable overexpression of Smad7 in fibroblasts from normal gingiva. Smad7‐overexpressing cells and control cells were incubated with CsA, and synthesis of type I collagen, production and activity of MMP‐2 and cellular proliferation were evaluated by ELISA, zymography, growth curve, bromodeoxyuridine incorporation assay and cell cycle analysis. The effects of CsA on cell viability and apoptosis of fibroblasts from normal gingiva were also evaluated. Western blot and immunofluorescence for phospho‐Smad2 were performed to measure the activation of TGF‐β1 signaling. Results: Although the treatment with CsA stimulated TGF‐β1 production in both control and Smad7‐overexpressing fibroblasts, its signaling was markedly inhibited in Smad7‐overexpressing cells, as revealed by low levels of phospho‐Smad2. In Smad7‐overexpressing cells, the effects of CsA on proliferation, synthesis of type I collagen and the production and activity of MMP‐2 were significantly blocked. Smad7 overexpression blocked CsA‐induced fibroblast proliferation via p27 regulation. Neither CsA nor Smad7 overexpression induced cell death. Conclusion: The data presented here confirm that TGF‐β1 expression is related to the molecular events associated with CsA‐induced gingival overgrowth and suggest that Smad7 overexpression is effective in blocking these events, including proliferation, type I collagen synthesis and MMP‐2 activity.     

LncRNA MAFG‐AS1 regulates human periodontal ligament stem cell proliferation and Toll‐like receptor 4 expression

LncRNA MAFG‐AS1 is predicted to interact with miR‐146a, which can target Toll‐like receptor 4 (TLR4), a key player in periodontitis. This study aimed to investigate the roles of MAFG‐AS1 in periodontitis. It was observed that MAFG‐AS1 was downregulated in the human periodontal ligament stem cells (PDLSCs) derived from periodontitis‐affected teeth. Dual‐luciferase assay revealed that co‐transfection of MAFG‐AS1 expression vector and miR‐146a mimic showed significantly lower relative luciferase activity comparing to co‐transfection of MAFG‐AS1 expression vector and negative control (NC) miRNA. However, MAFG‐AS1 and miR‐146a failed to affect each other. Interestingly, MAFG‐AS1 overexpression led to the upregulated TLR4. In addition, MAFG‐AS1 overexpression also led to the inhibited proliferation of PDLSCs. Therefore, MAFG‐AS1 may regulate the proliferation of PDLSCs and the expression of TLR4 to participate in periodontitis.