Production of inflammatory cytokines by human gingival fibroblasts stimulated by cell-surface preparations of Porphyromonas gingivalis

Porphyromonas gingivalis is a gram-negative rod associated with the progression of human periodontal disease. Inflammatory cytokines are believed to be the major pathological mediators in periodontal diseases. We therefore investigated the productions of interleukin-1beta (IL-1beta), interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor-alpha (TNF-alpha) in human gingival fibroblasts treated with lipopolysaccharide, polysaccharide and outer-membrane proteins from P. gingivalis ATCC 53977. Outer-membrane protein from P. gingivalis enhanced the production of IL-6 and IL-8 from the cells of periodontium in vitro as well as lipopolysaccharide did. The IL-8 production activity of polysaccharide from P. gingivalis was higher than that of other cell-surface components. The levels of IL-6 and IL-8 released from the P. gingivalis lipopolysaccharide-treated human gingival fibroblasts were lower than those of the same cells treated with lipopolysaccharides from Actinobacillus actinomycetemcomitans or Escherichia coli. Rabbit antisera against either outer-membrane protein or lipopolysaccharide inhibited the IL-6 and IL-8 production derived from human gingival fibroblasts stimulated sonicated supernatants from P. gingivalis. The present study suggests that, in addition to lipopolysaccharide, outer-membrane protein and polysaccharide of P. gingivalis are also pathological mediators in periodontal diseases.     

LPS刺激牙龈成纤维细胞IL-6、IL-8的产生和膜表面受体CD14的表达

目的：观察牙龈卟啉菌和中间普氏菌LPS刺激人牙龈成纤维细胞合成IL-6、IL-8的能力，并了解LPS是否通过细胞表面膜受体mCD14介导信号传导。方法：4种浓度的LPS在不同时间段。分别作用于体外培养的人牙龈成纤维细胞。采用ELISA检测IL-6、IL-8含量的变化，同时利用逆转录聚合酶链反应，进一步观察IL-6、IL-8，CD14在mRNA水平的表达特征。结果：ELISA和RT-PCR的反应结果证实，受LPS的刺激，细胞合成和分泌细胞因子IL-6、IL-8的能力明显增强，但未检测到细胞表面膜受体mCD14mRNA的表达。结论：LPS用于牙龈成纤维细胞合成和分泌细胞因子没有通过膜受体mCD14的介导。     

Hemoglobin and LPS act in synergy to amplify the inflammatory response

Vascular disruption and bleeding during periodontitis likely increase the levels of hemoglobin in gingival crevicular fluid. The aim of this study was to investigate the effect of hemoglobin on the inflammatory responses of human macrophages stimulated with lipopolysaccharides (LPS) isolated from periodontopathogens. The production of interleukin-1 beta (IL-1beta), IL-6, IL-8, and tumor necrosis factor alpha (TNF-alpha) by macrophages following challenges with Porphyromonas gingivalis and Fusobacterium nucleatum LPS in the presence or absence of human hemoglobin was analyzed by ELISA. The effect of hemoglobin on LPS-binding to macrophages was evaluated with (3)H-LPS. Hemoglobin and LPS from periodontopathogens acted in synergy to stimulate the production of high levels of IL-1beta, IL-6, IL-8, and TNF-alpha by macrophages. Hemoglobin also enhanced LPS-binding to macrophages. This study suggests that hemoglobin contributes to increases in the levels of pro-inflammatory mediators in periodontal sites by acting in synergy with LPS from periodontopathogens, thus favoring the progression of periodontitis.     

Induction of apoptosis in human gingival fibroblasts by a Porphyromonas gingivalis protease preparation.

Proteases produced by Porphyromonas gingivalis are believed to contribute to the pathogenesis of periodontal diseases. Here the cytotoxic effects of a purified preparation of a P. gingivalis protease with trypsin-like specificity were tested on human gingival fibroblasts in vitro. The active protease induced apoptotic cell death in the fibroblasts, as indicated by DNA fragmentation and the expression of 7A6 antigen. Thus, the production of proteases by periodontopathic bacteria could be an important factor in the induction of apoptosis of host cells in the aetiology of periodontal diseases.     

Effect of lipopolysaccharide from Porphyromonas gingivalis on prostaglandin E2 and interleukin-1β release from rat periosteal and human gingival fibroblasts in vitro

Lipopolysaccharide (LPS) was extracted from Porphyromonas gingivalis (W83) by the Westphal procedure, nuclease-digested and ultracentrifuged. Fibroblasts were obtained from human gingival tissue and rat periosteum, grown to confluence then stimulated in serum-free medium with 0.1, 1.0 and 10.0 micrograms/ml LPS. The levels of prostaglandin E2 (PGE2) and interleukin-1 beta (IL-1 beta) released were measured after 2, 4 and 6 d by specific radioimmunoassays. Unstimulated gingival fibroblasts produced low levels of PGE2 (24.5 +/- 1.5 (SD) ng/ml) and IL-1 beta (0.34 +/- 0.29 ng/ml). LPS stimulated statistically significant dose-related increases in PGE2 and IL-1 beta at the concentrations of LPS tested. At 10.0 micrograms/ml, LPS-stimulated fibroblasts produced 363.5 +/- 40.3 ng/ml PGE2 and 1.81 +/- 0.1 ng/ml IL-1 beta in 6 d. These results demonstrate that LPS from P. gingivalis is capable of stimulating PGE2 and IL-1 beta release from fibroblasts. This would appear to be an additional mechanism by which LPS can induce tissue breakdown in periodontal disease.     

Periodontal ligament and gingival fibroblasts participate in the production of TGF-β, interleukin (IL)-8 and IL-10

The aim of this study was to quantify and compare the production of transforming growth factor beta (TGF-β), interleukin (IL)-8 and IL-10 by human cultured periodontal ligament and gingival fibroblasts both obtained from the same donors challenged with lipopolysaccharide (LPS) from Porphyromonas gingivalis. Fibroblasts were exposed to 0.1-10 μg/mL of LPS from P. gingivalis and after 24 h the supernatants were collected and analyzed by enzyme-linked immunosorbent assay (ELISA). TGF-β protein production was upregulated in a concentration-dependent manner, mainly in gingival fibroblasts, which was statistically significant when challenged by 10 μg/mL LPS. Additionally, at this concentration, gingival fibroblasts had almost a two-fold increase in the amount of TGF-β when compared to periodontal ligament fibroblasts. Both periodontal ligament and gingival fibroblasts showed an increase in IL-8 production when challenged with 1 μg/mL and 10 μg/mL LPS. IL-10 production remained unaffected when challenged by any of the LPS concentrations tested in either periodontal ligament or gingival fibroblasts. Our results demonstrate that periodontal ligament and gingival fibroblasts when challenged by LPS from P. gingivalis with 24 h may play a critical role in producing TGF-β and IL-8 but not IL-10.     

Benzydamine reduces prostaglandin production in human gingival fibroblasts challenged with interleukin-1 beta or tumor necrosis factor alpha

Benzydamine [1-benzyl-3-(3-dimethylamino)propoxy-1H-indazole] is a drug with analgesic, anesthetic, antimicrobial and anti-inflammatory activity. The purpose of the present study was to investigate the effect of benzydamine on prostaglandin production in human gingival fibroblasts. Benzydamine significantly reduced the basal production of both prostaglandin E2 (PGE2) and 6-keto-PGF1 alpha, the stable breakdown product of prostaglandin I2 (PGI2), in unstimulated human gingival fibroblasts. When the cells were treated simultaneously with benzydamine and the cytokines IL-1 beta or TNF alpha, the agent benzydamine reduced (P < 0.05) the stimulatory effect of IL-1 beta and TNF alpha respectively, on PGE2 and PGI2 production in human gingival fibroblasts. Furthermore, benzydamine reduced (P < 0.05) both the basal level and the cytokine-induced 3H-arachidonic acid release 3H-(AA) in gingival fibroblasts. The addition of exogenous arachidonic acid to the cells resulted in enhanced PGE2 production, which was reduced (P < 0.05) in the presence of benzydamine. The study indicates that benzydamine reduces the prostaglandin synthesis in gingival fibroblasts, partly at the level of phospholipase A2, by diminishing the liberation of arachidonic acid (AA) from phospholipids, and partly at the level of cyclooxygenase. The inhibitory effect of benzydamine on prostaglandin production may explain the anti-inflammatory effect of the drug in the management of patients with oral inflammatory conditions.     

Effects of polyhexamethylene guanidine phosphate on human gingival fibroblasts

Objective: Polyhexamethylene guanidine phosphate (PHMG-P) was compared to chlorhexidine (CHX) in order to determine potential cytotoxic and immune-modulatory effects on human gingival fibroblasts.

Materials and methods: Cytotoxic effects of PHMG-P and CHX on human gingival fibroblasts were assessed using cell viability assay at various time points and concentrations. The effects of PHMG-P and CHX on the secretion of prostaglandin (PG) E₂, interleukin (IL)-6, IL-8 and matrix metalloproteinase (MMP)-1 by non-stimulated or IL-1β stimulated fibroblasts were evaluated by enzyme-linked immunosorbent assays.

Results: PHMG-P concentration 0.00009% led to the total loss of fibroblast viability within 24?h, whereas inhibition of fibroblast viability by CHX occurred at significantly higher concentrations of 0.0009% (p?p?2, IL-6, IL-8 and MMP-1. Treatment of IL-1β stimulated fibroblasts in combination with PHMG-P or CHX at concentrations of 0.000045 or 0.0.00009% resulted in significantly decreased PGE₂, IL-6, IL-8 and MMP-1 levels. PHMG-P or CHX alone did not affect the baseline secretion of PGE₂, IL-6, IL-8 or MMP-1 by gingival fibroblasts.

Conclusions: Cytotoxic effects on gingival fibroblasts were triggered by both PHMG-P and CHX at concentrations below those used in clinical practice. The tested antiseptics did not cause inflammation and reduced IL-1β-induced secretion of inflammatory mediators and collagenase by gingival fibroblasts, which suggests anti-inflammatory properties.     

Interleukin-1alpha stimulation in monocytes by periodontal bacteria: antagonistic effects of Porphyromonas gingivalis

Periodontal pathogenic bacteria are associated with elevated levels of interleukin-1alpha (IL-1alpha) but it is unclear if all species can induce cytokine production equally. Porphyromonas gingivalis may be able antagonize IL-1alpha induced by other species through the activity of its proteases or lipopolysaccharide (LPS). Monomac-6 cells and primary human monocytes were treated with culture supernatants from Porphyromonas gingivalis, Fusobacterium nucleatum, Campylobacter rectus, Actinobacillus actinomycetemcomitans, Prevotella intermedius, Veillonella atypical and Prevotella nigrescens. IL-1alpha protein levels were measured after 6 h of incubation. In addition, monocytes were co-stimulated with supernatants from P. gingivalis and other bacteria. The role of P. gingivalis proteases was tested using Arg-X and Lys-X mutant strains. The role of LPS was investigated using purified P. gingivalis LPS and polymixin depletion. All species tested induced significant IL-1alpha production, but P. gingivalis was the weakest. Co-stimulation of monocytes with P. gingivalis antagonized the ability of other bacterial species to induce IL-1alpha production. This effect was at its greatest with C. rectus (resulting in a 70% reduction). Gingipain mutant strains and chemical inhibition of protease activity did not reduce antagonistic activity. However, 100 ng/ml of P. gingivalis LPS can reproduce the antagonistic activity of P. gingivalis culture supernatants. Periodontitis-associated bacterial species stimulate IL-1alpha production by monocytes. P. gingivalis can antagonize this effect, and its LPS appears to be the crucial component. This study highlights the importance of mixed infections in the pathogenesis of periodontal disease because reduction of pro-inflammatory cytokine levels may impair the ability of the host to tackle infection.     

Cyclosporin A regulates interleukin-1beta and interleukin-6 expression in gingiva: implications for gingival overgrowth

BACKGROUND: Gingival overgrowth is a common side effect following the administration of cyclosporin A (CsA); however, the cellular mechanisms remain poorly understood. CsA's immunosuppressant properties involve the regulation of synthesis and cellular response to cytokines. A CsA-induced alteration in the cytokine profile within gingival tissue could provide a mechanism for gingival hyperplasia. The aim of this study was to investigate the effects of CsA on the production of 2 cytokines - interleukin-1beta (IL-1beta) and interleukin-6 (IL-6) - by both gingival fibroblasts and peripheral blood mononuclear cells (PBMC). METHODS: Cells were stimulated for 24 hours in the presence of CsA over a concentration range of 100 to 2,000 ng/ml and the resultant cytokine production determined by ELISA. In addition, levels of both cytokines within normal, inflamed, and overgrown gingival tissue were determined. RESULTS: CsA inhibited IL-6 production by gingival fibroblasts in a dose-dependent manner. In contrast, at a concentration of 2,000 ng/ml, CsA stimulated IL-6 production by PBMC (P <0.05). Fibroblasts derived from overgrown gingiva produced significantly higher levels of IL-6 than their normal counterparts (P <0.05). CsA inhibited IL-1beta production by PBMC over the whole concentration range (P <0.05). IL-1beta was not found in measurable quantities in any of the fibroblast cultures. Levels of IL-6 extracted from overgrown gingival tissue were significantly higher than in inflamed or normal tissue. In contrast IL-1beta levels in overgrown tissue were not statistically significantly greater than those in inflamed tissue. CONCLUSIONS: These results show that CsA does regulate cytokine expression in gingival tissue. This effect may play an important role in the pathogenesis of CsA-induced gingival overgrowth.     

Prostaglandin E2 secretion from gingival fibroblasts treated with interleukin-1β: effects of lipid extracts from Porphyromonas gingivalis or calculus

Complex lipids of Porphyromonas gingivalis have been identified in lipid extracts from calculus-contaminated root surfaces and in diseased gingival tissues. However, little is known about the biological effects of these complex lipids on host cells. The purpose of this study was to evaluate the effects of P. gingivalis or calculus lipids on prostaglandin secretion from gingival fibroblasts. Lipids were extracted from paired subgingival plaque and teeth samples, and calculus-contaminated root surfaces before and after scaling and root planing, in order to determine the relevant levels of lipid extracts for the treatment of gingival fibroblasts in culture. Primary cultures of gingival fibroblasts were exposed to lipid extracts from either P. gingivalis or calculus/teeth for a period of 7 days. Control and lipid-treated cultures were exposed to human recombinant interleukin-1β for 48 h and prostaglandin secretion from interleukin-1β-treated fibroblasts was compared with control and lipid-treated fibroblasts without interleukin-1β treatment. These experiments demonstrated that P. gingivalis lipids or calculus-tooth lipids potentiate interleukin-1β-mediated prostaglandin secretory responses from gingival fibroblasts. Additionally, P. gingivalis or calculus-tooth lipid extracts were readily taken up by gingival fibroblasts as measured by bacterial fatty acid recovery in lipid extracts of cultured fibroblasts. These results indicate that bacterial lipid penetration into gingival tissues in combination with a chronic inflammatory response may substantially potentiate prostaglandin secretion from gingival fibroblasts, thereby promoting tissue destructive processes associated with adult periodontitis.     

Interferon-γ stimulates CD14, TLR2 and TLR4 mRNA expression in gingival fibroblasts increasing responsiveness to bacterial challenge

ObjectiveTo investigate the potential effects of IFN-03A5 on the responsiveness of human gingival fibroblasts to bacterial challenge.DesignmRNA and protein expression of CD14, TLR2 and TLR4 in human gingival fibroblasts was detected by quantitative polymerase chain reaction (Q-PCR) and flow cytometry. The effect of preincubation with IFN-03A5 on subsequent bacterial LPS-induced expression of IL-6 and IL-8 by gingival fibroblasts was determined by ELISA. Bacterial LPS-induced IκBα degradation in human gingival fibroblasts was investigated by western blot.ResultsHuman gingival fibroblasts express CD14, TLR2 and TLR4 mRNAs. IFN-03A5, but not IL-103B2, induced mRNA expression of all three receptors and the expression of membrane bound CD14 protein. Pre-incubation of fibroblasts with IFN-03A5 and subsequent stimulation with Escherichia coli LPS or Porphyromonas gingivalis LPS led to increased production of IL-6 and IL-8. LPS-induced pro-inflammatory cytokine production was abrogated by a blocking antibody to CD14. Both E. coli LPS and P. gingivalis LPS induced IκBα degradation in human gingival fibroblasts.ConclusionOur data indicate that IFN-03A5 primes human gingival fibroblasts, through the upregulation of CD14 expression, which results in increased responsiveness to bacterial LPS challenge, as determined by pro-inflammatory cytokine production.     

The host cytokine response to Porphyromonas gingivalis is modified by gingipains

Background/aims:  Clinical studies indicate that primary proinflammatory cytokines, such as interleukin-1β (IL-1β) are elevated in the gingival crevice around teeth with periodontitis but the secondary cytokines and chemokines, IL-6 and IL-8, are not. The human gingival epithelial cells (HGECs) lining the gingival sulcus respond to perturbation by microbes of dental plaque by releasing a wide range of cytokines. Porphyromonas gingivalis , a putative periodontal pathogen, possesses numerous virulence factors some of which directly impact on the host response. In the present study, we sought to determine how P. gingivalis influences the inflammatory cytokine responses.
Methods:  HGECs were challenged with P. gingivalis and other putative periodontal pathogens, and the resultant production of IL-1β, IL-6, and IL-8 was assayed by enzyme-linked immunosorbent assay (ELISA). Culture supernatants and recombinant human cytokines were challenged with live P. gingivalis wild-type and gingipain-deficient strains and the resultant cytokine profile was assessed by ELISA and Western blot.
Results:  We show here that primary HGECs challenged with live P. gingivalis result in high levels of IL-1β but not the related secondary cytokines IL-6 and IL-8. We further demonstrate that cytokine response differences are the result of the action of P. gingivalis proteases, with lysine gingipain being the most effective.
Conclusion:  We conclude that P. gingivalis , through lysine gingipain, can subvert the protective host proinflammatory response by direct cytokine degradation. Changes in the crevicular cytokine profile have consequences in periodontal disease pathogenesis that should be considered in the development of diagnostic and therapeutic modalities.     

Retinoic acid-inducible gene-I is induced in gingival fibroblasts by lipopolysaccharide or poly IC: possible roles in interleukin-1beta, -6 and -8 expression

Retinoic acid-inducible gene-I (RIG-I) is a member of the DExH family of proteins, and little is known of its biological function in the oral region. We previously reported that interleukin 1beta (IL-1beta) induced RIG-I expression in gingival fibroblasts. In this study, we studied the mechanism of RIG-I expression induced by lipopolysaccharide (LPS) or double-stranded RNA (dsRNA) in gingival fibroblasts. We also addressed the role of RIG-I in the expression of IL-1beta, IL-6 and IL-8 in gingival fibroblasts stimulated with LPS or dsRNA. We stimulated cultured human gingival fibroblasts with LPS or dsRNA, and examined the expression of RIG-I mRNA and protein. The effect of cycloheximide, a protein synthesis inhibitor, on RIG-I induction by these stimuli was examined. The expression of IL-1beta, IL-6 and IL-8 in gingival fibroblasts transfected with RIG-I cDNA stimulated with LPS or dsRNA was examined. LPS or dsRNA induced the expression of mRNA and protein for RIG-I in concentration- and time-dependent manners. We also examined the localization of RIG-I, and found that it was expressed in cytoplasm. Cycloheximide did not suppress the LPS or dsRNA-induced RIG-I expression. Introduction of RIG-I cDNA into gingival fibroblasts resulted in enhanced expression of IL-1beta, IL-6 and IL-8; moreover, overexpression of RIG-I stimulated with LPS or dsRNA synergistically increased expression of IL-1beta, IL-6 and IL-8. RIG-I may have important roles in the innate immune response in the regulation of IL-1beta, IL-6 and IL-8 expression in gingival fibroblasts in response to LPS and dsRNA.     

Production of inflammatory cytokines by human gingival fibroblasts stimulated by cell‐surface preparations of Porphyromonas gingivalis

Porphyromonas gingivalis is a gram‐negative rod associated with the progression of human periodontal disease. Inflammatory cytokines are believed to be the major pathological mediators in periodontal diseases. We therefore investigated the productions of interleukin‐1β (IL‐1β), interleukin‐6 (IL‐6), interleukin‐8 (IL‐8), and tumor necrosis factor‐α (TNF‐α) in human gingival fibroblasts treated with lipopolysaccharide, polysaccharide and outer‐membrane proteins from P. gingivalis ATCC 53977. Outer‐membrane protein from P. gingivalis enhanced the production of IL‐6 and IL‐8 from the cells of periodontium in vitro as well as lipopolysaccharide did. The IL‐8 production activity of polysaccharide from P. gingivalis was higher than that of other cell‐surface components. The levels of IL‐6 and IL‐8 released from the P. gingivalis lipopolysaccharide‐treated human gingival fibroblasts were lower than those of the same cells treated with lipopolysaccharides from Actinobacillus actinomycetemcomitans or Escherichia coli. Rabbit antisera against either outer‐membrane protein or lipopolysaccharide inhibited the IL‐6 and IL‐8 production derived from human gingival fibroblasts stimulated sonicated supernatants from P. gingivalis. The present study suggests that, in addition to lipopolysaccharide, outer‐membrane protein and polysaccharide of P. gingivalis are also pathological mediators in periodontal diseases.     

High IL-6 synthesis in cultured fibroblasts isolated from radicular cysts

OBJECTIVE: Inflammatory cytokines have been reported to be related with inflammation and expansion of jaw cysts. In this study, to examine the relationship between radicular cysts and inflammatory cytokines, it was found that there was notable unique evidence on cytokine synthesis from fibroblasts isolated from radicular cysts. METHODS: The expression of such cytokines, namely, interleukin-1beta, IL-1beta, IL-6, IL-8, IL-10, tumour necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), transforming growth factor-beta1 (TGF-beta1), and granulocyte-macrophage colony-stimulating (GM-CSF) mRNA, in nine radicular cysts was examined and compared with that detected in six specimens of healthy gingival mucosa. Furthermore, separating all fibroblasts from their respective radicular cysts, healthy gingival mucosa, and healthy periodontal ligaments, these fibroblast groups were cultured without stimulators and a supernatant for each was obtained to analyse IL-1beta, IL-6, IL-8, TNF-alpha, and IFN-gamma by ELISA. RESULTS: Differences between radicular cysts and healthy gingival mucosa were not clearly shown by the expression of cytokine mRNA. Analysing inflammatory cytokine synthesis in fibroblast groups from these three kinds of tissues, surprisingly, the levels of IL-6 mRNA and protein were recognised to be higher in fibroblasts of radicular cysts than in those of control tissues by ELISA and a real-time RT-PCR. Significant differences in the cultured supernatants of these fibroblast groups were not recognised in the release of IL-1beta, IL-8, TNF-alpha, and IFN-gamma by ELISA. CONCLUSIONS: From these results, it was suggested that fibroblasts inducing IL-6 production might play important roles in the expansion of radicular cysts. It is considered that fibroblasts around radicular cysts may lead to high IL-6 synthesis over time in chronic inflammation.     

Epithelial cell pro-inflammatory cytokine response differs across dental plaque bacterial species

Aim: The dental plaque is comprised of numerous bacterial species, which may or may not be pathogenic. Human gingival epithelial cells (HGECs) respond to perturbation by various bacteria of the dental plaque by production of different levels of inflammatory cytokines, which is a putative reflection of their virulence. The aim of the current study was to determine responses in terms of interleukin (IL)-1 β , IL-6, IL-8 and IL-10 secretion induced by Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum and Streptococcus gordonii in order to gauge their virulence potential.
Materials and Methods: HGECs were challenged with the four bacterial species, live or heat killed, at various multiplicity of infections and the elicited IL-1 β , IL-6, IL-8 and IL-10 responses were assayed by enzyme-linked immunosorbent assay.
Results: Primary HGECs challenged with live P. gingivalis produced high levels of IL-1 β , while challenge with live A. actinomycetemcomitans gave high levels of IL-8. The opportunistic pathogen F. nucleatum induces the highest levels of pro-inflammatory cytokines, while the commensal S. gordonii is the least stimulatory.
Conclusion: We conclude that various dental plaque biofilm bacteria induce different cytokine response profiles in primary HGECs that may reflect their individual virulence or commensal status.