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

Avenanthramide-C Shows Potential to Alleviate Gingival Inflammation and Alveolar Bone Loss in Experimental Periodontitis

Periodontal disease is a chronic inflammatory disease that leads to the gradual destruction of the supporting structures of the teeth including gums, periodontal ligaments, alveolar bone, and root cementum. Recently, interests in alleviating symptoms of periodontitis (PD) using natural compounds is increasing. Avenanthramide-C (Avn-C) is a polyphenol found only in oats. It is known to exhibit various biological properties. To date, the effect of Avn-C on PD pathogenesis has not been confirmed. Therefore, this study aimed to verify the protective effects of Avn-C on periodontal inflammation and subsequent alveolar bone erosion in vitro and in vivo. Upregulated expression of catabolic factors, such as matrix metalloproteinase 1 (MMP1), MMP3, interleukin (IL)-6, IL-8, and COX2 induced by lipopolysaccharide and proinflammatory cytokines, IL-1β, and tumor necrosis factor α (TNF-α), was dramatically decreased by Avn-C treatment in human gingival fibroblasts and periodontal ligament cells. Moreover, alveolar bone erosion in the ligature-induced PD mouse model was ameliorated by intra-gingival injection of Avn-C. Molecular mechanism studies revealed that the inhibitory effects of Avn-C on the upregulation of catabolic factors were mediated via ERK (extracellular signal-regulated kinase) and NF-κB pathway that was activated by IL-1β or p38 MAPK and JNK signaling that was activated by TNF-α, respectively. Based on this study, we recommend that Avn-C may be a new natural compound that can be applied to PD treatment.

Fibroblasts at the curtain call: from ensemble to principal dancers in immunometabolism and inflammaging

Inflammation is a necessary step in response to injuries, being vital in restoring homeostasis and facilitating tissue healing. Among the cells that play a crucial role in inflammatory responses, stromal cells, including fibroblasts, have an undeniable significance in fine-tuning the magnitude of mediators that directly affect hyper-inflammatory responses and tissue destruction. Fibroblasts, the dominant cells in the gingival connective tissue, are a very heterogeneous population of cells, and more recently they have been receiving well deserved attention as central players and often the 'principal dancers' of many pathological processes ranging from inflammation and fibrosis to altered immunity and cancer. The goal of the current investigation is to dive into the exact role of the stromal fibroblast and the responsible mechanistic factors involved in both regulation and dysregulation of the inflammatory responses. This article reviews the most recent literature on how fibroblasts, in their different activation states or subtypes, play a crucial role in contributing to inflammatory outcomes. We will focus on recent findings on inflammatory diseases. We will also provide connections regarding the stromal-immune relationship, which supports the idea of fibroblast coming out from the 'ensemble' of cell types to the protagonist role in immunometabolism and inflammaging. Additionally, we discuss the current advances in variation of fibroblast nomenclature and division into clusters with their own suggested function and particularities in gene expression. Here, we provide a perspective for the periodontal implications, discussing the fibroblast role in the infection-driven and inflammatory mediated diseases such as periodontitis.

Free titanium particles and P. gingivalis lipopolysaccharide create a potentially synergistical effect in a periimplantitis model

OBJECTIVE

Our aim was to examine the effect of titanium particles and lipopolysaccharide (LPS) from P. gingivalis on the inflammatory profile expression of human gingival fibroblasts (hGFs), cultured on rough titanium discs, in an in vitro peri-implantitis simulation.

DESIGN

Human gingival fibroblasts cultured on SLA and TCP surfaces were challenged with LPS, titanium particles or both. At 24, 48 and 72 h after treatment, MTT assay was performed to assess cell proliferation. FDA/PI staining was performed for the same time periods, in order to evaluate cell viability/apoptosis. At 5 and 7 days after the treatment, qPCR was performed to assess gene expressions of IL-6, IL-8 and COL1A1, as well as SEM on titanium discs.

RESULTS

All groups presented a significant increase of their population between the time periods of examination. Regarding the interleukin gene expression, the combination of LPS and particles significantly increased the levels of Interleukin-8. Treatment with LPS and particles also induced a significant increase of Interleukin-6 and collagen. FDA/PI microscopy has revealed several apoptotic cells in the treatment groups. SEM micrographs have shown the difficulty of hGFs to adhere on rough surfaces.

CONCLUSIONS

The combination of titanium particles and LPS significantly upregulated the expression of IL-6, IL-8 and Col-1a. It appears that particles may arouse similar reactions to the endotoxin, while synergistically intensifying it.

Novel ITGB6 variants cause hypoplastic-hypomineralized amelogenesis imperfecta and taurodontism: characterization of tooth phenotype and review of literature

OBJECTIVES

To characterize phenotype and genotype of amelogenesis imperfecta (AI) in a Thai patient, and review of literature.

MATERIALS AND METHODS

Variants were identified using trio-exome and Sanger sequencing. The ITGB6 protein level in patient's gingival cells was measured. The patient's deciduous first molar was investigated for surface roughness, mineral density, microhardness, mineral composition, and ultrastructure.

RESULTS

The patient exhibited hypoplastic-hypomineralized AI, taurodontism, and periodontal inflammation. Exome sequencing identified the novel compound heterozygous ITGB6 mutation, a nonsense c.625 G > T, p.(Gly209*) inherited from mother and a splicing c.1661-3 C > G from father, indicating AI type IH. The ITGB6 level in patient cells was significantly reduced, compared with controls. Analyses of a patient's tooth showed a significant increase in roughness while mineral density of enamel and microhardness of enamel and dentin were significantly reduced. In dentin, carbon was significantly decreased while calcium, phosphorus, and oxygen levels were significantly increased. Severely collapsed enamel rods and a gap in dentinoenamel junction were observed. Of six affected families and eight ITGB6 variants that have been reported, our patient was the only one with taurodontism.

CONCLUSION

We report the hypoplasia/hypomineralization/taurodontism AI patient with disturbed tooth characteristics associated with the novel ITGB6 variants and reduced ITGB6 expression, expanding genotype, phenotype, and understanding of autosomal recessive AI.

Local and Systemic Effects of Porphyromonas gingivalis Infection

Porphyromonas gingivalis, a gram-negative anaerobe, is a leading etiological agent in periodontitis. This infectious pathogen can induce a dysbiotic, proinflammatory state within the oral cavity by disrupting commensal interactions between the host and oral microbiota. It is advantageous for P. gingivalis to avoid complete host immunosuppression, as inflammation-induced tissue damage provides essential nutrients necessary for robust bacterial proliferation. In this context, P. gingivalis can gain access to the systemic circulation, where it can promote a prothrombotic state. P. gingivalis expresses a number of virulence factors, which aid this pathogen toward infection of a variety of host cells, evasion of detection by the host immune system, subversion of the host immune responses, and activation of several humoral and cellular hemostatic factors.

Differential gene expression profiles of periodontal soft tissue from rat teeth after immediate and delayed replantation: a pilot study

Purpose

In dental avulsion, delayed replantation usually has an uncertain prognosis. After tooth replantation, complex inflammatory responses promote a return to periodontal tissue homeostasis. Various types of cytokines are produced in the inflammatory microenvironment, and these cytokines determine the periodontal tissue response. This study aimed to identify the gene expression profiles of replanted teeth and evaluate the functional differences between immediate and delayed replantation.

Methods

Maxillary molars from Sprague-Dawley rats were extracted, exposed to a dry environment, and then replanted. The animals were divided into 2 groups according to the extra-oral time: immediate replantation (dry for 5 minutes) and delayed replantation (dry for 60 minutes). Either 3 or 7 days after replantation, the animals were sacrificed. Periodontal soft tissues were harvested for mRNA sequencing. Hallmark gene set enrichment analysis was performed to predict the function of gene-gene interactions. The normalized enrichment score (NES) was calculated to determine functional differences.

Results

The hallmark gene sets enriched in delayed replantation at 3 days were oxidative phosphorylation (NES=2.82, Q<0.001) and tumor necrosis factor-alpha (TNF-α) signaling via the nuclear factor kappa light chain enhancer of activated B cells (NF-κB) pathway (NES=1.52, Q=0.034). At 7 days after delayed replantation, TNF-α signaling via the NF-κB pathway (NES=–1.82, Q=0.002), angiogenesis (NES=–1.66, Q=0.01), and the transforming growth factor-beta signaling pathway (NES=–1.46, Q=0.051) were negatively highlighted.

Conclusions

Differentially expressed gene profiles were significantly different between immediate and delayed replantation. TNF-α signaling via the NF-κB pathway was marked during the healing process. However, the enrichment score of this pathway changed in a time-dependent manner between immediate and delayed replantation.

Activation of Gingival Fibroblasts by Bacterial Cyclic Dinucleotides and Lipopolysaccharide

Human gingival fibroblasts (HGFs) recognize microbe-associated molecular patterns (MAMPs) and respond with inflammatory proteins. Simultaneous impacts of bacterial cyclic di-guanosine monophosphate (c-di-GMP), cyclic di-adenosine monophosphate (c-di-AMP), and lipopolysaccharide (LPS) on gingival keratinocytes have been previously demonstrated, but the effects of these MAMPs on other periodontal cell types, such as gingival fibroblasts, remain to be clarified. The present aim was to examine the independent and combined effects of these cyclic dinucleotides and LPS on interleukin (IL) and matrix metalloproteinase (MMP) response of HGFs. The cells were incubated with c-di-GMP and c-di-AMP, either in the presence or absence of Porphyromonas gingivalis LPS, for 2 h and 24 h. The levels of IL-8, -10, and -34, and MMP-1, -2, and -3 secreted were measured by the Luminex technique. LPS alone or together with cyclic dinucleotides elevated IL-8 levels. IL-10 levels were significantly increased in the presence of c-di-GMP and LPS after 2 h but disappeared after 24 h of incubation. Concurrent treatment of c-di-AMP and LPS elevated MMP-1 levels, whereas c-di-GMP with LPS suppressed MMP-2 levels but increased MMP-3 levels. To conclude, we produce evidence that cyclic dinucleotides interact with LPS-mediated early response of gingival fibroblasts, while late cellular response is mainly regulated by LPS.

Increased levels of interleukin-32 isoforms alpha, beta, gamma, and delta in the gingival crevicular fluid and plasma of the patients with periodontitis

BACKGROUND AND OBJECTIVE

Interleukin (IL)-32, which has been recently reported to be associated with periodontitis, has been suggested to have pleiotropic effect due to its 9 different isoforms. The aim of this study was to investigate the levels of IL-32α, IL-32β, IL-32γ, IL-32δ isoforms in gingival crevicular fluid (GCF) and plasma before and after non-surgical periodontal treatment in patients with periodontitis (P).

MATERIALS AND METHODS

Twenty-seven P and 27 periodontally healthy controls (C) were recruited in this study. Non-surgical periodontal treatment was performed to periodontitis patients. GCF and plasma sampling and clinical periodontal parameters were evaluated before and 1 month after treatment. Enzyme-linked immunosorbent assay was used to analyze the levels of IL-32α, IL-32β, IL-32γ, IL-32δ isoforms in GCF and plasma samples.

RESULTS

The levels of IL-32α, IL-32β, IL-32γ, and IL-32δ in plasma and GCF were significantly higher in patients with periodontitis than healthy controls (P < .001). In P group, plasma and GCF IL-32α, IL-32β, IL-32γ, and IL-32δ levels after non-surgical periodontal treatment were lower when compared to baseline (P < .001). Moreover, there was a positive correlation between GCF and plasma IL-32α, IL-32β, IL-32γ, and IL-32δ levels in all groups at baseline and after treatment (P < .05).

CONCLUSION

The study supported that there was a relationship between elevated levels of IL-32 isoforms and periodontitis. Also, our novel findings suggest that the pro-inflammatory role of IL-32 in the periodontitis may be originated from IL-32α, IL-32β, IL-32γ, and IL-32δ isoforms.

Effect of ScLL and 15d-PGJ2 on viability and cytokine release in LPS-stimulated fibroblasts: an in vitro study

This study evaluated the effect of a cyclopentenone-type PG, 15-Deoxy-Δ12,14-PG J2 (15d-PGJ2), and lectin (ScLL) on the viability of human gingival fibroblasts (HGFs), and on IL-6 and TGFβ-1 release by these fibroblasts, stimulated with lipopolysaccharide (LPS). HGFs were stimulated with LPS 10 μg/ml and treated with 15d-PGJ2 1 and 2 μg/ml, and ScLL 2 and 5 μg/ml, for 1 and 3h, and then evaluated for viability by MTT assay. Supernatant was collected to detect IL-6 and TGFβ-1 release, by ELISA. Positive control was cells kept in Dulbecco's Modified Eagle's Medium, and negative control was those kept in LPS. Data were analyzed by ANOVA and Dunnett's test (α = 0.05). No significant difference was found in viability among experimental groups at 1h (p > 0.05). Percentage of ScLL 5 µg/ml viable cells was similar to that of positive control at evaluated periods (p > 0.05), whereas the other groups had lower levels than the positive control (p < 0.05). IL-6 release was statistically higher for ScLL 5 μg/ml and 15d-PGJ2 2 µg/ml at 1h, compared with the other treated groups and positive control (p < 0.05). No significant differences were found among the groups at 3h (p > 0.05), except for ScLL 2 µg/ml and 15d-PGJ2 1 µg/ml, which showed lower IL-6 release compared with that of negative control (p < 0.05). No significant difference was found among the groups for TGFβ-1 release (p > 0.05). Results indicated that ScLL 5 μg/ml did not interfere in viability, and ScLL 2 µg/ml and 15d-PGJ2 1 µg/ml demonstrated reduced IL-6 release. Tested substances had no effect on TGFβ-1 release.

Anti-inflammatory and anti-resorptive efficacy of adrenergic blockers on late replanted rat incisors

BACKGROUND/AIM

In addition to their anti-inflammatory and anti-osteoclastogenesis properties, adrenergic blockers may also have promising anti-resorptive effects that can prevent root resorption when teeth are replanted because of avulsion. The aim of this study was to investigate the effects of phentolamine (Ph) and propranolol (Pr) in gels on the repair process of late replanted rat incisors. A further aim was to evaluate the biocompatibility of both drugs to human periodontal ligament fibroblasts (HPDLFs).

MATERIALS AND METHODS

Forty-eight maxillary right incisors were extracted from male Wistar rats, stored in paper napkins for 60 minutes, and randomly allocated to one of eight groups (n = 6). The root canal, root surface, and alveolus were treated with 0.75 µg/mL Ph gel (Ph0.75), 10 µg/mL Ph gel (Ph10), 100 µg/mL Ph gel (Ph100), 2.5 µg/mL Pr gel (Pr2.5), 10 µg/mL Pr gel (Pr10), 100 µg/mL Pr gel (Pr100), or sodium carboxymethylcellulose gel (CMC) before replantation. In the control group (CH), only the root canal was treated with calcium hydroxide paste. Thirty days following surgery, the animals were euthanized, and the right hemimaxilla was removed to perform micro-CT and histomorphometric analysis to determine osteoclastic activity. Ethanolic solutions of Ph10 and Pr10 were selected based on the in vivo study, and the viability of HPDLFs stimulated with lipopolysaccharide was determined by MTT assays.

RESULTS

The micro-CT and histomorphometric analysis revealed no significant differences among the treatments (P > .05). The presence of active osteoclasts was significantly decreased in the Ph10 and Pr10 groups (P < .05). Ph10 and Pr10 produced statistically similar cell survival rates compared to the control group (P > .05).

CONCLUSIONS

Ph10 and Pr10 significantly decreased osteoclastogenesis in delayed replanted rat teeth and were not cytotoxic toward HPDLFs.

CD73-dependent adenosine dampens interleukin-1β-induced CXCL8 production in gingival fibroblasts: Association with heme oxygenase-1 and adenosine monophosphate-activated protein kinase

BACKGROUND

During inflammation, stressed or infected cells can release adenosine triphosphate (ATP) to the extracellular medium, which can be hydrolyzed to adenosine by ectonucleotidases such as ectonucleoside triphosphate diphosphohydrolase 1 (CD39) and 5'-nucleotidase (CD73). The role of CD73 in the modulation of cytokine release by human gingival fibroblasts (HGFs) remains underexplored. Here, we investigated whether CD73-mediated hydrolysis of extracellular ATP (eATP) could affect interleukin (IL)-1β-induced CXCL8 secretion.

METHODS

The levels of mRNA expression of adenosine receptors, CD39 and CD73 of periodontitis samples were retrieved from a public database. Moreover, HGF mRNA levels were measured by quantitative reverse transcription-polymerase chain reaction (RT-qPCR) after 3, 6, or 24 hours of IL-1β stimulation. IL-1β-induced CXCL8 protein levels were measured after pretreatment with 100-µM eATP in the presence or absence of CD73 inhibitor. The effect of eATP degradation to adenosine on CXCL8 levels was investigated using agonist and antagonist of adenosine receptors.

RESULTS

Levels of CD39, CD73, and adenosine receptor mRNA were differentially modulated by IL-1β. ATP pretreatment impaired IL-1β-induced CXCL8 secretion and required activation of heme oxygenase-1 (HO-1) and phosphorylated adenosine monophosphate-activated protein kinase (pAMPK). The inhibition of CD73 or the inhibition of adenosine receptors abrogated the ATP effect on CXCL8 secretion.

CONCLUSIONS

CD73-generated adenosine dampens IL-1β-induced CXCL8 in HGFs and involves HO-1 and pAMPK signaling. These results imply that CD73 is a negative regulator of the inflammatory microenvironment, suggesting that this ectoenzyme could be involved in the generation of deficient CXCL8 gradient in chronic inflammation.

Investigation of foreign materials in gingival lesions: a clinicopathologic, energy-dispersive microanalysis of the lesions and in vitro confirmation of pro-inflammatory effects of the foreign materials

OBJECTIVES

This study aimed to evaluate the clinical and histopathologic features of gingival lesions containing foreign material (GLFMs). In parallel, the composition of the foreign material and its effects in primary human gingival fibroblasts (HGFs) were investigated.

STUDY DESIGN

Eighty-six GLFMs were retrieved from an oral pathology biopsy service. Clinical and microscopic data were analyzed, and the composition of the particles was identified by using energy-dispersive X-ray spectroscopy (EDX). Furthermore, HGFs were stimulated with silica (SiO₂) microparticles to investigate the production of collagen type 1 (COL-1), matrix metalloproteinase 2 (MMP2), and inflammatory cytokines.

RESULTS

GLFMs were most commonly found in women (60.5%) and most frequently described as white plaques. Histopathologic examination identified verrucous hyperplasia in 59% and epithelial dysplasia in 28% of the cases. EDX microanalysis revealed that Si (94%) was the most frequently detected foreign element. SiO₂ microparticles induced higher COL-1 expression; higher levels of proinflammatory cytokines, such as interleukin-6 (IL-6), IL-8, and transforming growth factor-β, and increased MMP-2 activity in HGFs.

CONCLUSIONS

There was a strong association between the presence of foreign material in the gingiva and white verrucous clinical lesions. In addition, the most common element in the foreign material was Si, and our in vitro findings demonstrate the importance of silica-mediated effects on gingival fibroblasts.

Dental Pulp Fibroblasts Response after Stimulation with HEMA and Adhesive System

This study evaluated in vitro cell viability and metabolism, nitric oxide release and production of chemokines by cultured human dental pulp fibroblasts (DPF) under contact with HEMA and Single Bond. Cultures of DPF were established by means of an explant technique. Once plated, cells were kept under contact with increasing concentrations of HEMA (10, 100 and 1000 nM) or Single Bond (SB) [10-fold serially diluted in culture medium (10-4, 10-3 and 10-2 v/v)] and also with polymerized SB components. Cytotoxicity was assessed by Trypan Blue exclusion method and MTT [3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. Nitric oxide release on cell supernatant was detected by Griess Method whereas chemokines (CXCL12 and CXCL8) were detected by ELISA. RT-qPCR was employed for chemokines gene expression analysis. Cytotoxic tests showed significant differences for SB 10-2. None of the tested materials significantly altered NO levels. Protein levels of CXCL12 were significantly decreased only by HEMA. On the other hand, while CXCL12 mRNA remained unaltered, gene expression of CXCL8 had significant decrease with all materials, except for polymerized SB. In conclusion, Single Bond and HEMA at various concentrations, decreased expression and production of molecules involved in inflammatory processes and, therefore, the use of adhesive systems such as pulp capping materials must be viewed with caution due to its large cytotoxic effect when in close contact with the pulp.

Litsea japonica Leaf Extract Suppresses Proinflammatory Cytokine Production in Periodontal Ligament Fibroblasts Stimulated with Oral Pathogenic Bacteria or Interleukin-1β

Periodontal disease, a chronic disease caused by bacterial infection, eventually progresses to severe inflammation and bone loss. Regulating excessive inflammation of inflamed periodontal tissues is critical in treating periodontal diseases. The periodontal ligament (PDL) is primarily a connective tissue attachment between the root and alveolar bone. PDL fibroblasts (PDLFs) produce pro-inflammatory cytokines in response to bacterial infection, which could further adversely affect the tissue and cause bone loss. In this study, we determined the ability of Litsea japonica leaf extract (LJLE) to inhibit pro-inflammatory cytokine production in PDLFs in response to various stimulants. First, we found that LJLE treatment reduced lipopolysaccharide (LPS)-induced pro-inflammatory cytokine (interleukin-6 and interleukin-8) mRNA and protein expression in PDLFs without cytotoxicity. Next, we observed the anti-inflammatory effect of LJLE in PDLFs after infection with various oral bacteria, including Fusobacterium nucleatum, Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia. These anti-inflammatory effects of LJLE were dose-dependent, and the extract was effective following both pretreatment and posttreatment. Moreover, we found that LJLE suppressed the effect of interleukin-1 beta-induced pro-inflammatory cytokine production in PDLFs. Taken together, these results indicate that LJLE has anti-inflammatory activity that could be exploited to prevent and treat human periodontitis by controlling inflammation.

Dual action of bacteriocin PLNC8 αβ through inhibition of Porphyromonas gingivalis infection and promotion of cell proliferation

Periodontitis is a chronic inflammatory disease that is characterised by accumulation of pathogenic bacteria, including Porphyromonas gingivalis, in periodontal pockets. The lack of effective treatments has emphasised in an intense search for alternative methods to prevent bacterial colonisation and disease progression. Bacteriocins are bacterially produced antimicrobial peptides gaining increased consideration as alternatives to traditional antibiotics. We show rapid permeabilisation and aggregation of P. gingivalis by the two-peptide bacteriocin PLNC8 αβ. In a cell culture model, P. gingivalis was cytotoxic against gingival fibroblasts. The proteome profile of fibroblasts is severely affected by P. gingivalis, including induction of the ubiquitin-proteasome pathway. PLNC8 αβ enhanced the expression of growth factors and promoted cell proliferation, and suppressed proteins associated with apoptosis. PLNC8 αβ efficiently counteracted P. gingivalis-mediated cytotoxicity, increased expression of a large number of proteins and restored the levels of inflammatory mediators. In conclusion, we show that bacteriocin PLNC8 αβ displays dual effects by acting as a potent antimicrobial agent killing P. gingivalis and as a stimulatory factor promoting cell proliferation. We suggest preventive and therapeutical applications of PLNC8 αβ in periodontitis to supplement the host immune defence against P. gingivalis infection and support wound healing processes.

Antibacterial and Anti-inflammatory Potential of Morus alba Stem Extract

Background:

Periodontitis, a chronic inflammatory disease, is the leading cause of tooth loss in adults. Evidence for the anti inflammatory activity of M. alba Stem Extract (MSE) in periodontal disease is limited.

Objective:

The study aimed to investigate the inhibitory effect of MSE on the growth of periodontopathic bacteria and expression of interleukin (IL)-6 and IL-8 in Porphyromonas gingivalis Lipopolysaccharide (LPS)-stimulated human Periodontal Ligament (hPDL) fibroblasts.

Methods:

The antimicrobial activities of MSE were tested against P. gingivalis and Aggregatibacter actinomycetemcomitans by the disk diffusion, the minimum inhibitory concentration and the minimal bactericidal concentration methods. Cytotoxicity of P. gingivalis LPS and MSE on hPDL fibroblasts was determined by MTS assay. The expression of cytokines (IL-6 and IL-8) mRNA and proteins in hPDL fibroblasts was measured using the reverse transcription-qPCR and enzyme-linked immunosorbent assay, respectively.

Results:

MSE exhibited antibacterial activities against P. gingivalis and A. actinomycetemcomitans with the zones of inhibition of 10.00 ± 0.33 mm and 17.33 ± 0.58 mm, respectively. MIC and MBC values for MSE against P. gingivalis were 62.5 μg/ml. The MIC and MBC values against A. actinomycetemcomitans were 250 μg/mL and 500 μg/ml, respectively. P. gingivalis LPS was shown to mediate the expression of pro-inflammatory cytokines in hPDL fibroblasts. However, treatment with MSE concentrations of 2.5 and 5.0 μg/ml significantly suppressed P. gingivalis LPS-induced IL-6 and IL-8 mRNA and protein expression (p< 0.05).

Conclusion:

The present study demonstrates that MSE has antibacterial activity against two putative periodontal pathogens. MSE suppressed IL-6 and IL-8 expression in P. gingivalis LPS-stimulated hPDL fibroblasts, indicating a possible anti-inflammatory effect. Thus, it is a potential adjunctive agent for the treatment of periodontitis.

Effects of grape seed extract on periodontal disease: an experimental study in rats

Objective

This study aimed to demonstrate the effect of grape seed extract (GSE) on periodontitis.

Material and Methods

Ligature induced periodontitis was created in 40 rats and they were assigned to four equal groups. One group was fed laboratory diet (group A) while three groups received GSE additionally. Silk ligatures were placed around the cervical area of the mandibular first molars for four weeks to induce periodontitis. The GSE groups were reallocated regarding GSE consumption as: for two weeks before ligation (group B; totally eight weeks), from ligation to two weeks after removal of the ligature (group C; totally six weeks), and for two weeks from ligature removal (group D; totally two weeks). Sections were assessed histologically and immunohistochemically. Inflammatory cell number (ICN), connective tissue attachment level (CAL), osteoclast density (OD), IL-10 and TGF-β stainings in gingival epithelium (GE), connective tissue (GC), and periodontal ligament (PL) were used as the study parameters.

Results

Lower ICN, higher CAL, and lower OD were observed in the GSE groups (p<0.05). IL-10 was more intensive in the GSE groups and in the GEs (p<0.05). Group B showed the highest IL-10 for PL (p<0.05). TGF-ß was higher in the GEs of all groups (p<0.017).

Conclusions

The results suggest anti-inflammatory activities of GSE, but further investigations are needed for clarification of these activities.

Effects of IL-10 and glucose on expression of OPG and RANKL in human periodontal ligament fibroblasts

The effects of interleukin-10 (IL-10) and glucose on mRNA and protein expression of osteoprotegerin (OPG), and its ligand, receptor activator of nuclear factor-κB ligand (RANKL), were investigated in human periodontal ligament fibroblasts (HPDLFs). Primary HPDLFs were treated with different concentrations of IL-10 (0, 1, 10, 25, 50, and 100 ng/mL) or glucose (0, 5.5, 10, 20, 30, and 40 mmol/L). Changes in mRNA and protein expression were examined using the reverse-transcription polymerase chain reaction (RT-PCR) and Western blot analysis, respectively. After IL-10 treatment, mRNA and protein levels of OPG were increased, while mRNA and protein levels of RANKL were decreased (P<0.05), both in a concentration-dependent manner. Glucose stimulation had the opposite concentration-dependent effect to that of IL-10 on OPG and RANKL expression. IL-10 upregulated OPG expression and downregulated RANKL expression, whereas high glucose upregulated RANKL and downregulated OPG in HDPLFs. Abnormal levels of IL-10 and glucose may contribute to the pathogenesis of periodontal disease.

Cytokines during periodontal wound healing: potential application for new therapeutic approach

Regeneration of periodontal tissues is one of the main goals of periodontal therapy. However, current treatment, including surgical approach, use of membrane to allow maturation of all periodontal tissues, or use of enamel matrix derivatives, presents limitations in their indications and outcomes leading to the development of new tissue engineering strategies. Several cytokines are considered as key molecules during periodontal destruction process. However, their role during each phase of periodontal wound healing remains unclear. Control and modulation of the inflammatory response and especially, release of cytokines or activation/inhibition in a time- and spatial-controlled manner may be a potential perspective for periodontal tissue engineering. The aim of this review was to summarize the specific role of several cytokines during periodontal wound healing and the potential therapeutic interest of inflammatory modulation for periodontal regeneration especially related to the expression sequence of cytokines.

Periodontal Disease-Induced Atherosclerosis and Oxidative Stress

Periodontal disease is a highly prevalent disorder affecting up to 80% of the global population. Recent epidemiological studies have shown an association between periodontal disease and cardiovascular disease, as oxidative stress plays an important role in chronic inflammatory diseases such as periodontal disease and cardiovascular disease. In this review, we focus on the mechanisms by which periodontopathic bacteria cause chronic inflammation through the enhancement of oxidative stress and accelerate cardiovascular disease. Furthermore, we comment on the antioxidative activity of catechin in atherosclerosis accelerated by periodontitis.

Effect of glycated albumin and cranberry components on interleukin-6 and matrix metalloproteinase-3 production by human gingival fibroblasts

BACKGROUND AND OBJECTIVE

Gingival fibroblasts have the potential to participate in periodontal inflammation and breakdown, producing interleukin (IL)-6 and matrix metalloproteinase (MMP)-3. Advanced glycation end products (AGEs), formed during diabetic hyperglycemia, might aggravate periodontal inflammation. The cranberry contains anti-inflammatory polyphenols, which inhibit proinflammatory activities of lipopolysaccharide (LPS)- and IL-1β-stimulated human cells. Little is known of its effects on gingival fibroblast IL-6 or MMP-3 production stimulated by AGEs. The objectives were to determine cranberry effects on IL-6 and MMP-3 production by gingival fibroblasts exposed to the representative AGE, glycated human serum albumin (G-HSA), or LPS ± G-HSA.

MATERIAL AND METHODS

Cranberry high molecular weight non-dialyzable material (NDM), was derived from cranberry juice. Normal human gingival fibroblasts were incubated with G-HSA or normal HSA or Porphyromonas gingivalis LPS (1 μg/mL) ± G-HSA, in the presence or absence of preincubation with NDM. IL-6 and MMP-3 were measured by enzyme-linked immunosorbent assay. Data were analyzed using one-way analysis of variance and Scheffe's F procedure.

RESULTS

IL-6 production was stimulated by G-HSA or LPS (p < 0.01), which was inhibited in both cases by NDM (p < 0.002). [G-HSA+LPS] synergistically stimulated IL-6 production (p < 0.0001), which was inhibited by NDM. MMP-3 levels were not stimulated by G-HSA but were decreased by LPS (p < 0.02). [G-HSA+LPS] increased MMP-3 production significantly, vs. LPS (p = 0.0005). NDM inhibited MMP-3 levels in the presence of G-HSA or LPS, and in the presence of [G-HSA+LPS] (p < 0.0001).

CONCLUSIONS

G-HSA ± LPS may have differential effects on IL-6 and MMP-3 production by human gingival fibroblasts, but both are inhibited by NDM. The study suggests that cranberry phenols may be useful in regulating the host response and perhaps treating periodontitis in patients with poorly controlled diabetes.

A Biofilm Pocket Model to Evaluate Different Non-Surgical Periodontal Treatment Modalities in Terms of Biofilm Removal and Reformation, Surface Alterations and Attachment of Periodontal Ligament Fibroblasts

BACKGROUND AND AIM

There is a lack of suitable in vitro models to evaluate various treatment modalities intending to remove subgingival bacterial biofilm. Consequently, the aims of this in vitro-study were: a) to establish a pocket model enabling mechanical removal of biofilm and b) to evaluate repeated non-surgical periodontal treatment with respect to biofilm removal and reformation, surface alterations, tooth hard-substance-loss, and attachment of periodontal ligament (PDL) fibroblasts.

MATERIAL AND METHODS

Standardized human dentin specimens were colonized by multi-species biofilms for 3.5 days and subsequently placed into artificially created pockets. Non-surgical periodontal treatment was performed as follows: a) hand-instrumentation with curettes (CUR), b) ultrasonication (US), c) subgingival air-polishing using erythritol (EAP) and d) subgingival air-polishing using erythritol combined with chlorhexidine digluconate (EAP-CHX). The reduction and recolonization of bacterial counts, surface roughness (Ra and Rz), the caused tooth substance-loss (thickness) as well as the attachment of PDL fibroblasts were evaluated and statistically analyzed by means of ANOVA with Post-Hoc LSD.

RESULTS

After 5 treatments, bacterial reduction in biofilms was highest when applying EAP-CHX (4 log10). The lowest reduction was found after CUR (2 log10). Additionally, substance-loss was the highest when using CUR (128±40 µm) in comparison with US (14±12 µm), EAP (6±7 µm) and EAP-CHX (11±10) µm). Surface was roughened when using CUR and US. Surfaces exposed to US and to EAP attracted the highest numbers of PDL fibroblasts.

CONCLUSION

The established biofilm model simulating a periodontal pocket combined with interchangeable placements of test specimens with multi-species biofilms enables the evaluation of different non-surgical treatment modalities on biofilm removal and surface alterations. Compared to hand instrumentation the application of ultrasonication and of air-polishing with erythritol prevents from substance-loss and results in a smooth surface with nearly no residual biofilm that promotes the reattachment of PDL fibroblasts.

Secreted gingipains from Porphyromonas gingivalis colonies exert potent immunomodulatory effects on human gingival fibroblasts

Periodontal pathogens, including Porphyromonas gingivalis, can form biofilms in dental pockets and cause inflammation, which is one of the underlying mechanisms involved in the development of periodontal disease, ultimately leading to tooth loss. Although P. gingivalis is protected in the biofilm, it can still cause damage and modulate inflammatory responses from the host, through secretion of microvesicles containing proteinases. The aim of this study was to evaluate the role of cysteine proteinases in P. gingivalis colony growth and development, and subsequent immunomodulatory effects on human gingival fibroblast. By comparing the wild type W50 with its gingipain deficient strains we show that cysteine proteinases are required by P. gingivalis to form morphologically normal colonies. The lysine-specific proteinase (Kgp), but not arginine-specific proteinases (Rgps), was associated with immunomodulation. P. gingivalis with Kgp affected the viability of gingival fibroblasts and modulated host inflammatory responses, including induction of TGF-β1 and suppression of CXCL8 and IL-6 accumulation. These results suggest that secreted products from P. gingivalis, including proteinases, are able to cause damage and significantly modulate the levels of inflammatory mediators, independent of a physical host-bacterial interaction. This study provides new insight of the pathogenesis of P. gingivalis and suggests gingipains as targets for diagnosis and treatment of periodontitis.

Palatal mucosa derived fibroblasts present an adaptive behavior regarding cytokine secretion when grafted onto the gingival margin

Background

Considering that grafted gingival tissue might have to be adapted to the receptor area and that fibroblasts have the ability to respond to bacterial stimuli through the release of various cytokines, this study investigated whether fibroblasts from the palatal mucosa behave differently when grafted onto the gingival margin regarding cytokine secretion.

Methods

Biopsies from the palatal mucosa were collected at the time of free gingival graft surgery, and after four months re-collection was performed upon surgery for root coverage. Fibroblasts were isolated by the explant technique, cultured and stimulated with Porphyromonas gingivalis (Pg) and Escherichia coli (Ec) LPS for 24 or 48 h for comparative evaluation of the secretion of cytokines and chemokines, such as IL-6, IL-8/CXCL8, MIP-1α/CCL3, TGF-β, VEGF and CXCL16. Unstimulated cells were used as the control group. Cells were tested for viability through MTT assay, and secretion of cytokines and chemokines was evaluated in the cell supernatants by Enzyme-Linked Immunosorbent Assay (ELISA).

Results

Fibroblasts from the palatal mucosa maintained the same secretion pattern of IL-6 when grafted onto the gingival margin. On the contrary, fibroblasts from the marginal gingival graft showed increased secretion of IL-8/CXCL8 even in the absence of stimulation. Interestingly, MIP-1α/CCL3 secretion by fibroblasts from the marginal gingival graft was significantly increased after 48 hours of stimulation with Pg LPS and after 24 h with Ec LPS. Only fibroblasts from the marginal gingival graft showed secretion of TGF-β. VEGF and CXCL16 secretion were not detected by both subsets of fibroblasts.

Conclusion

Fibroblasts from the palatal mucosa seem to be adapted to local conditions of the site microenvironment when grafted onto the gingival marginal area. This evidence supports the effective participation of fibroblasts in the homeostasis of the marginal periodontium through secretion modulation of important inflammatory mediators.

Evaluation of peri-implant mucosa: clinical, histopathological and immunological aspects

OBJECTIVE

The aim was to compare the inflammatory response in peri-implant mucosa between patients with peri-implantitis (PP-group) and patients with healthy peri-implant tissues (HP-group).

MATERIALS AND METHODS

Two fragments of peri-implant mucosa of 18 patients were collected and serial sections were performed for histological and immunohistochemical analysis.

RESULTS

When compared with HP-group, PP-group showed higher immunostained cell density for TGF-β, IL-17 and CD31, beyond greater density of red cells, leukocytes, mast cells chymase (MCC) and mast cell tryptase (MCT). HP-group patients showed higher IL-13 expression and increased amount of collagen fibres when compared with PP-group. In PP-group there was significant positive correlation between MCT density and density of blood vessels immunostained, and between MCC density and density of blood vessels immunostained. There was significant negative correlation between the IL-17 density and collagen percentage.

CONCLUSIONS

This study demonstrated that in patients with peri-implantitis there was higher of TGF-β and IL-17, indicating that these cytokines are directly involved in the inflammatory process. Thus, understanding the influence of cytokines in the peri-implantitis installation, new therapies could be developed in order to inhibit the synthesis of IL-17 and induce synthesis of IL-13 in peri-implant tissue, contributing to increase the longevity of the implant.

CCL3 and CXCL12 production in vitro by dental pulp fibroblasts from permanent and deciduous teeth stimulated by Porphyromonas gingivalis LPS

OBJECTIVE

The aim of this study was to compare the production of the chemokines CCL3 and CXCL12 by cultured dental pulp fibroblasts from permanent (PDPF) and deciduous (DDPF) teeth under stimulation by Porphyromonas gingivalis LPS (PgLPS).

MATERIAL AND METHODS

Primary culture of fibroblasts from permanent (n=3) and deciduous (n=2) teeth were established using an explant technique. After the fourth passage, fibroblasts were stimulated by increasing concentrations of PgLPS (0-10 µg/mL) at 1, 6 and 24 h. The cells were tested for viability through MTT assay, and production of the chemokines CCL3 and CXCL12 was determined through ELISA. Comparisons among samples were performed using One-way ANOVA for MTT assay and Two-way ANOVA for ELISA results.

RESULTS

Cell viability was not affected by the antigen after 24 h of stimulation. PgLPS induced the production of CCL3 by dental pulp fibroblasts at similar levels for both permanent and deciduous pulp fibroblasts. Production of CXCL12, however, was significantly higher for PDPF than DDPF at 1 and 6 h. PgLPS, in turn, downregulated the production of CXCL12 by PDPF but not by DDPF.

CONCLUSION

These data suggest that dental pulp fibroblasts from permanent and deciduous teeth may present a differential behavior under PgLPS stimulation.

In vitro regulation of CCL3 and CXCL12 by bacterial by-products is dependent on site of origin of human oral fibroblasts

INTRODUCTION

Production of chemokines by tissue resident cells is one of the main mechanisms involved in the inflammatory infiltrate formation during inflammation. The specific ability of fibroblasts from different oral tissues such as gingiva, periodontal ligament, and dental pulp from permanent and deciduous teeth in producing the chemokines CCL3 and CXCL12 under stimulation by bacterial products commonly found in endodontic infections was investigated.

METHODS

Cultures of fibroblasts from gingiva and periodontal ligament as well as from dental pulp from permanent and deciduous teeth were established by using an explant technique and stimulated with increasing concentrations of Escherichia coli lipopolysaccharide (EcLPS) and Enterococcus faecalis lipoteichoic acid (EfLTA) for 1, 6, and 24 hours. Supernatants were tested for CCL3 and CXCL12 by enzyme-linked immunosorbent assay.

RESULTS

In general, CCL3 production was induced by EcLPS in the 4 fibroblast subtypes and by EfLTA in fibroblasts from gingiva and periodontal ligament. Constitutive CXCL12 synthesis decreased in all fibroblast subtypes especially under stimulation with EcLPS. Fibroblast from permanent deciduous teeth was the cell type presenting the most expressive reduction in CXCL12 release by both stimuli. On the basis of computational matching of CXCL12 mRNA with the microRNAs miR-141 and miR-200a, their expression was also investigated. Although detected in the fibroblasts, these molecules remained unaltered by bacterial by-product stimulation.

CONCLUSIONS

EcLPS and EfLTA induced the production of CCL3 and unbalanced the synthesis of CXCL12 in a manner dependent on the specific tissue origin of fibroblasts.

Gingival fibroblasts from periodontitis patients exhibit inflammatory characteristics in vitro

OBJECTIVE

Gingival fibroblasts (GFs) are an important regulatory cell type in the progression of periodontitis. This study aimed to compare the expression levels of genes associated with inflammation, extracellular matrix degradation and bone destruction in GFs isolated from healthy and periodontitis subjects in the absence and presence of Porphyromonas gingivalis.

DESIGNS

Primary GFs from healthy (n=10) and periodontitis subjects (n=10) were stimulated in vitro with viable P. gingivalis ATCC 49417 and 3 clinical isolates of P. gingivalis with type II fimbriae from one healthy subject (KUMC-H1) and two periodontitis patients (KUMC-P1, -P2). The mRNA expression of proinflammatory cytokines (interleukin (IL)-6, IL-8, IL-1B), anti-inflammatory cytokines (IL-4, IL-10), matrix metalloproteinase (MMP)-1 and 2, tissue inhibitor matrix metalloproteinase (TIMP)-3 and osteoprotegerin (OPG) were assessed using real-time PCR. The levels of IL-6, IL-1β and TIMP-3 protein were measured by an enzyme-linked immunosorbent assay.

RESULTS

The mRNA expression of IL-6, IL-1B and TIMP-3 was higher in the periodontitis group compared with the healthy group, whereas IL-4 expression was higher in the healthy group both in the absence and presence of the P. gingivalis strains. The expression levels of IL-6, IL-1β and TIMP-3 protein were also higher in the periodontitis group in the absence and/or presence of the P. gingivalis strains. There was inter-strain variability among P. gingivalis strains in the ability to induce expression of the proinflammatory cytokines, MMPs and OPG and in the ability to degrade IL-6 protein.

CONCLUSION

High expression of proinflammatory cytokines and TIMP-3 and low expression of IL-4 can be a signature of GFs associated with periodontitis.

Porphyromonas gingivalis downregulates the immune response of fibroblasts

Background

Porphyromonas gingivalis is a key pathogen in periodontitis, an inflammatory disease leading to destruction of bone and tooth-supporting tissue. P. gingivalis possesses a number of pathogenic properties to enhance growth and survival, including proteolytic gingipains. Accumulating data shows that gingipains are involved in the regulation of host inflammatory responses. The aim of this study was to determine if P. gingivalis infection modulates the inflammatory response of fibroblasts, including the release of chemokines and cytokines. Human gingival fibroblasts or primary dermal fibroblasts were pre-stimulated with tumor-necrosis factor-α (TNF- α) and cocultured with P. gingivalis. Gingipain inhibitors were used to explore the effect of gingipains. CXCL8 levels were determined with ELISA and the relative levels of various inflammatory mediators were determined by a cytokine assay.

Results

TNF-α-triggered CXCL8 levels were completely abolished by viable P. gingivalis, whereas heat-killed P. gingivalis did not suppress CXCL8. Accumulation of CXCL8 was partially restored by an arginine-gingipain inhibitor. Furthermore, fibroblasts produced several inflammatory mediators, notably chemokines, all of which were suppressed by viable P. gingivalis.

Conclusion

These findings provide evidence that fibroblast-derived inflammatory signals are modulated by heat-instable gingipains, whereby the bacteria can escape killing by the host immune system and promote its own growth and establishment. In addition, we show that fibroblasts are important mediators of inflammation in response to infection and thereby play a crucial role in determining the nature and magnitude of the invasion of immune cells.

The concentrations of IL-8 and IL-6 in gingival crevicular fluid during nickel-chromium alloy porcelain crown restoration

We explored gum irritation and cytotoxicity caused by nickel-chromium (Ni-Cr) alloy porcelain by interleukin-8 (IL-8), interleukin-6 (IL-6) and gingival crevicular fluid (GCF) volumes at different time points peri-crown restoration. This prospective study was conducted in 60 young adults. The total amount and concentrations of IL-8 and IL-6 per site, GCF volumes, and blood neutrophil counts were performed prior to and at 1 week, 3 months, and 6 months after Ni-Cr alloy-porcelain crown restoration. Thirty male and 30 female subjects, aged 20-35 years old were enrolled. The total amount and concentrations of IL-8 and IL-6 per site, GCF volumes increased after nickel-chromium (Ni-Cr) alloy-porcelain crown restoration, and reached its peak at the third month as the GCF volume increased by 52.20 %, the total amount and concentrations of IL-8 increased by 112.11 and 22.75 %; the total amount and concentrations of IL-6 increased by 77.66 and 17.17 % when compared to baseline. In particular, the increase of IL-8 concentration was found in female patients at 3 months after restoration; while the neutrophil count of the peripheral blood did not change significantly. The increase in the total amount and the concentrations of IL-8 and IL-6 and GCF volume may be related to the cytotoxicity induced by Ni-Cr alloy. The significant increase of IL-8 concentration in females indicates that more attention should be given to women during Ni-Cr alloy porcelain crown restoration.

MyD88 or TRAM knockdown regulates interleukin (IL)-6, IL-8, and CXCL12 mRNA expression in human gingival and periodontal ligament fibroblasts

BACKGROUND

In a previous report, it was shown that Toll-like receptor (TLR) 2 knockdown modulates interleukin (IL)-6 and IL-8 but not the chemokine CXCL12, an important mediator with inflammatory and proangiogenic effects, in human gingival fibroblasts (HGF) and human periodontal ligament fibroblasts (HPDLF). This study investigates whether knocking down two important TLR adaptor molecules, such as myeloid differentiation protein 88 (MyD88) and TRIF-related adaptor molecule (TRAM), could affect mRNA expression of IL-6, IL-8, and CXCL12 in HGF and HPDLF.

METHODS

After small interfering (si) RNA-mediated silencing of MyD88 or TRAM, HGF and HPDLF were stimulated with Porphyromonas gingivalis (Pg) lipopolysaccharide (LPS) or two synthetic ligands of TLR2 (Pam2CSK4 and Pam3CSK4) for 6 hours. IL-6, IL-8, and CXCL12 mRNAs were evaluated by quantitative polymerase chain reaction.

RESULTS

Knockdown of MyD88 or TRAM partially impaired the IL-8 mRNA upregulation in both fibroblast subpopulations. Similarly, IL-6 upregulation was partially prevented by siMyD88 or siTRAM in HGF stimulated with Pg LPS, as well as in both fibroblast subtypes challenged with Pam2CSK4. Conversely, constitutive CXCL12 mRNA levels were upregulated by MyD88 or TRAM knockdown in non-stimulated cells.

CONCLUSIONS

These results suggest that TLR adaptor molecules knockdown, such as MyD88 or TRAM, can decrease IL-6 and IL-8 mRNA and increase CXCL12 mRNA expression in HGF and HPDLF. This can be an important step for better understanding the mechanisms that control the inflammatory cytokine and chemokine expression, which in turn contributes to periodontal pathogenesis.

Toll-like receptor 2 knockdown modulates interleukin (IL)-6 and IL-8 but not stromal derived factor-1 (SDF-1/CXCL12) in human periodontal ligament and gingival fibroblasts

BACKGROUND

Fibroblasts are now seen as active components of the immune response because these cells express Toll-like receptors (TLRs), recognize pathogen-associated molecular patterns, and mediate the production of cytokines and chemokines during inflammation. The innate host response to lipopolysaccharide (LPS) from Porphyromonas gingivalis is unusual inasmuch as different studies have reported that it can be an agonist for Toll-like receptor 2 (TLR2) and an antagonist or agonist for Toll-like receptor 4 (TLR4). This study investigates and compares whether signaling through TLR2 or TLR4 could affect the secretion of interleukin (IL)-6, IL-8, and stromal derived factor-1 (SDF-1/CXCL12) in both human gingival fibroblasts (HGF) and human periodontal ligament fibroblasts (HPDLF).

METHODS

After small interfering RNA-mediated silencing of TLR2 and TLR4, HGF and HPDLF from the same donors were stimulated with P. gingivalis LPS or with two synthetic ligands of TLR2, Pam2CSK4 and Pam3CSK4, for 6 hours. IL-6, IL-8, and CXCL12 mRNA expression and protein secretion were evaluated by quantitative polymerase chain reaction and enzyme-linked immunosorbent assay, respectively.

RESULTS

TLR2 mRNA expression was upregulated in HGF but not in HPDLF by all the stimuli applied. Knockdown of TLR2 decreased IL-6 and IL-8 in response to P. gingivalis LPS, or Pam2CSK4 and Pam3CSK4, in a similar manner in both fibroblasts subpopulations. Conversely, CXCL12 remained unchanged by TLR2 or TLR4 silencing.

CONCLUSION

These results suggest that signaling through TLR2 by gingival and periodontal ligament fibroblasts can control the secretion of IL-6 and IL-8, which contribute to periodontal pathogenesis, but do not interfere with CXCL12 levels, an important chemokine in the repair process.

Expression levels of novel cytokine IL-32 in periodontitis and its role in the suppression of IL-8 production by human gingival fibroblasts stimulated with Porphyromonas gingivalis

Background

IL-32 was recently found to be elevated in the tissue of rheumatoid arthritis and inflammatory bowel disease. Periodontitis is a chronic inflammatory disease caused by polymicrobial infections that result in soft tissue destruction and alveolar bone loss. Although IL-32 is also thought to be associated with periodontal disease, its expression and possible role in periodontal tissue remain unclear. Therefore, this study investigated the expression patterns of IL-32 in healthy and periodontally diseased gingival tissue. The expression of IL-32 in cultured human gingival fibroblasts (HGF) as well as effects of autocrine IL-32 on IL-8 production from HGF were also examined.

Methods

Periodontal tissue was collected from both healthy volunteers and periodontitis patients, and immunofluorescent staining was performed in order to determine the production of IL-32. Using real-time PCR and ELISA, mRNA expression and protein production of IL-32 in HGF, stimulated by Porphyromonas gingivalis (Pg), were also investigated.

Results

Contrary to our expectation, the production of IL-32 in the periodontitis patients was significantly lower than in the healthy volunteers. According to immunofluorescent microscopy, positive staining for IL-32 was detected in prickle and basal cell layers in the epithelium as well as fibroblastic cells in connective tissue. Addition of fixed Pgin vitro was found to suppress the otherwise constitutive expression of IL-32 mRNA and protein in HGF. However, recombinant IL-32 in vitro inhibited the expression of IL-8 mRNA by HGF stimulated with Pg. Interestingly, anti-IL-32 neutralizing antibody upregulated the IL-8 mRNA expression in non-stimulated HGF, indicating that constitutive expression of IL-32 in HGF suppressed IL-8 mRNA expression in the absence of bacterial stimulation.

Conclusion

These results indicate that IL-32 is constitutively produced by HGF which can be suppressed by Pg and may play a role in the downregulation of inflammatory responses, such as IL-8 production, in periodontal tissue.