Actinobacillus actinomycetemcomitans lipopolysaccharide regulates matrix metalloproteinase, tissue inhibitors of matrix metalloproteinase, and plasminogen activator production by human gingival fibroblasts: A potential role in connective tissue destructio

Regulation of adhesin synthesis in Aggregatibacter actinomycetemcomitans

Aggregatibacter actinomycetemcomitans is a gram-negative bacterium associated with periodontal disease and a variety of disseminated extra-oral infections. Tissue colonization is mediated by fimbriae and non-fimbriae adhesins resulting in the formation of a sessile bacterial community or biofilm, which confers enhanced resistance to antibiotics and mechanical removal. The environmental changes experienced by A. actinomycetemcomitans during infection are detected and processed by undefined signaling pathways that alter gene expression. In this study, we have characterized the promoter region of the extracellular matrix protein adhesin A (EmaA), which is an important surface adhesin in biofilm biogenesis and disease initiation using a series of deletion constructs consisting of the emaA intergenic region and a promotor-less lacZ sequence. Two regions of the promoter sequence were found to regulate gene transcription and in silico analysis indicated the presence of multiple transcriptional regulatory binding sequences. Analysis of four regulatory elements, CpxR, ArcA, OxyR, and DeoR, was undertaken in this study. Inactivation of arcA, the regulator moiety of the ArcAB two-component signaling pathway involved in redox homeostasis, resulted in a decrease in EmaA synthesis and biofilm formation. Analysis of the promoter sequences of other adhesins identified binding sequences for the same regulatory proteins, which suggests that these proteins are involved in the coordinate regulation of adhesins required for colonization and pathogenesis.

The virulence factor GroEL promotes gelatinase secretion from cells in the osteoblast lineage: Implication for direct crosstalk between bacteria and adult cells

OBJECTIVE

The aim of this study was to demonstrate the influence of the virulence factor GroEL on osteoblast behavior by characterizing the changes of secreted gelatinases.

DESIGN

ELISA was performed to detect GroEL from samples from patients with or without apical periodontitis. An apical periodontitis model was established in rats and the expression of MMP-2, MMP-9 and NF-κB was evaluated by immunofluorescence staining. The primary osteoblasts and osteoblast-like MC3T3 cells were stimulated with recombinant GroEL, and gelatin zymography was used to determine the activity and expression of MMP-2 and MMP-9. Western blot was used to screen signaling pathways, and immunofluorescence staining was performed to confirm the activated signaling.

RESULTS

First, we found expression of GroEL to be higher in oral saliva, gingival crevicular fluid and periradicular granulation tissue of patients with apical periodontitis than it was in healthy control patients. We next found that recombinant GroEL could increase the activity of the gelatinases, MMP-2 and MMP-9, which were secreted by both primary osteoblasts and MC3T3 cells. In a rat apical periodontitis model, strong expression of gelatinases was confirmed. Then, we found that GroEL-enhanced gelatinase activity was mediated through activation of NF-κB signaling. Acetylated NF-κB accumulated in the cell nucleus and bound to the promoter of MMP-2 and MMP-9 genes, thus initiating their high expression.

CONCLUSION

This study reveals a direct interaction between oral bacteria and adult cells by demonstrating that gelatinase secretion is induced by GroEL, which partially explains bone resorption through gelatinase activation.

Th2 cell regulatory and effector molecules single nucleotide polymorphisms and periodontitis

To investigate the association between T helper 2 (Th2) cell regulatory and effector molecules' genetic polymorphisms and periodontitis. Single nucleotide polymorphisms (SNPs) of 11 Th2 cell regulatory or effector molecules genes (CD28, CTLA4, IL4, IL5, IL6, IL9, IL10, IL13, IL4R, GATA3, STAT6, and rs1537415; total 130 SNPs) were studied in Chinese nonsmokers (163 periodontitis-free controls, 141 periodontitis patients) using Sequenom iPlex assays. SNPs potentially associated with periodontitis (adjusted allelic P < 0.1) in this cross-sectional study were further investigated via meta-analysis. Allele G of rs4553808 in promoter of CTLA4 was more frequently detected in periodontitis than controls (P < 0.005), but did not remain significant after age and gender adjustment. Haplotype (GTT) in a block of three CTLA4 SNPs (rs4553808, rs16840252, rs5742909) was significantly associated with periodontitis. Meta-analysis of SNPs identified indicated allele T of CTLA4 rs5742909 (3 studies; 461 control, 369 periodontitis) and allele G of IL6 rs1800796 (18 studies; 2760 control, 2442 periodontitis) were significantly associated with periodontitis (OR = 1.44 and OR = 1.30, respectively). Within limitations of this study, a haplotype of CTLA4 concerning Th2 cell regulation, may be associated with periodontitis in Chinese nonsmokers followed. Meta-analysis indicated rs5742909 of CTLA4 and rs1800796 of IL6 appeared significantly associated with periodontitis.

Modulatory effect of curcumin analogs on the activation of metalloproteinases in human periodontal stem cells

Periodontitis progresses due to increased levels of active metalloproteinases (MMPs) and the imbalance between MMPs and their tissue inhibitors (TIMPs). Natural curcumin limits the lytic activity of MMPs but has low cellular uptake. Use of synthetic curcumin analogs could be a means of overcoming this limitation of treatment efficiency. Human periodontal stem cells were isolated from gingival tissue, gingival ligament fibers, periodontal ligament, and alveolar bone. The effect of five synthetic curcumin analogs was compared with that of natural curcumin by assessing cytotoxicity [by 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide (MTT) assay], the cellular uptake (by fluorometry), the proteolytic activities of MMP-2 and -9 (by zymography), and the levels of TIMP-1 (by ELISA). Our results indicated increased cytotoxicity of synthetic curcumins for doses between 100 and 250 μM. At a concentration of 10 μM, cellular uptake of synthetic curcumins varied depending on their chemical structure. The curcumin compounds modulated pro-MMP-2 levels and increased TIMP-1 production. There was no detectable synthesis of pro-MMP-9 and no activation of MMPs 2 and 9. Gingival tissue and gingival ligament fiber stem cells were most responsive to treatment, showing inverse correlations between pro-MMP-2 and TIMP-1 levels. In conclusion, synthetic curcumins influenced the balance between pro-MMP-2 and TIMP-1 in human periodontal stem cells in vitro, and this could open perspectives for their application as adjuvants in periodontal therapy.

Effects of Monolaurin on Oral Microbe-Host Transcriptome and Metabolome

The aim of this in vitro study was to evaluate the effects of monolaurin against Aggregatibacter actinomycetemcomitans (Aa) and determine their effects on the host transcriptome and metabolome, using an oral cell/bacteria co-culture dual-chamber model to mimic the human periodontium. For this, the Aa, was applied to cross the monolayer of epithelial keratinocytes (OBA-9) to reach the fibroblasts layer (HGF-1) in the basal chamber. The Monolaurin treatments (25 or 50 μM) were added immediately after the inoculation of the dual-chamber with Aa. After 24 h, the transcriptional factors and metabolites produced were quantified in the remaining cell layers (insert and basal chamber) and in supernatant released from the cells. The genes IL-1α, IL-6, IL-18, and TNF analyzed in HGF-1 concentrations showed a decreased expression when treated with both concentration of Monolaurin. In keratinocytes, the genes IL-6, IL-18, and TNF presented a higher expression and the expression of IL-1α decreased when treated with the two cited concentrations. The production of glycerol and pyruvic acid increased, and the 2-deoxytetronic acid NIST, 4-aminobutyric acid, pinitol and glyceric acid, presented lower concentrations because of the treatment with 25 and/or 50 μM of Monolaurin. Use of monolaurin modulated the immune response and metabolite production when administered for 24 h in a dual-chamber model inoculated with A. actinomycetemcomitans. In summary, this study indicates that monolaurin had antimicrobial activity and modulated the host immune response and metabolite production when administered for 24 h in a dual-chamber model inoculated with A. actinomycetemcomitans.

Oral microbe-host interactions: influence of β-glucans on gene expression of inflammatory cytokines and metabolome profile

Background

The aim of this study was to evaluate the effects of β-glucan on the expression of inflammatory mediators and metabolomic profile of oral cells [keratinocytes (OBA-9) and fibroblasts (HGF-1) in a dual-chamber model] infected by Aggregatibacter actinomycetemcomitans. The periodontopathogen was applied and allowed to cross the top layer of cells (OBA-9) to reach the bottom layer of cells (HGF-1) and induce the synthesis of immune factors and cytokines in the host cells. β-glucan (10 μg/mL or 20 μg/mL) were added, and the transcriptional factors and metabolites produced were quantified in the remaining cell layers and supernatant.

Results

The relative expression of interleukin (IL)-1-α and IL-18 genes in HGF-1 decreased with 10 μg/mL or 20 μg/mL of β-glucan, where as the expression of PTGS-2 decreased only with 10 μg/mL. The expression of IL-1-α increased with 20 μg/mL and that of IL-18 increased with 10 μg/mL in OBA-9; the expression of BCL 2, EP 300, and PTGS-2 decreased with the higher dose of β-glucan. The production of the metabolite 4-aminobutyric acid presented lower concentrations under 20 μg/mL, whereas the concentrations of 2-deoxytetronic acid NIST and oxalic acid decreased at both concentrations used. Acetophenone, benzoic acid, and pinitol presented reduced concentrations only when treated with 10 μg/mL of β-glucan.

Conclusions

Treatment with β-glucans positively modulated the immune response and production of metabolites.

Localization and expression pattern of amelotin, odontogenic ameloblast-associated protein and follicular dendritic cell-secreted protein in the junctional epithelium of inflamed gingiva

The purpose of this study is to elucidate the localization of amelotin (AMTN), odontogenic ameloblast-associated protein (ODAM) and follicular dendritic cell-secreted protein (FDC-SP) at the junctional epithelium (JE) in Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans infected mice and inflamed and non-inflamed human gingiva. We performed immunostaining to determine the localization and expression pattern of AMTN, ODAM and FDC-SP. AMTN, ODAM and FDC-SP in A. actinomycetemcomitans infected mice did not change dramatically compared with non-infected mice. AMTN and FDC-SP expressions were observed stronger in P. gingivalis infected mice at early stage. However, at the following stage, the coronal part of the AMTN expression disappeared from the JE, and FDC-SP expression decreased due to severe inflammation by P. gingivalis. ODAM expressed internal and external basal lamina, and the expression increased not only at early stage but also at the following stage in the inflammatory JE induced by P. gingivalis. In the human gingival tissues, AMTN was detected at the surface of the sulcular epithelium and JE in the non-inflamed and inflamed gingiva, and the localization did not change the process of inflammation. ODAM and FDC-SP were more widely detected at the sulcular epithelium and JE in the non-inflamed gingiva. In the inflamed gingiva, localization of ODAM and FDC-SP was spread into the gingival epithelium, compared to AMTN. These studies demonstrated that the expression pattern of AMTN, ODAM and FDC-SP at the JE were changed during inflammation process and these three proteins might play an important role in the resistance to inflammation.

Leptin and Pro-Inflammatory Stimuli Synergistically Upregulate MMP-1 and MMP-3 Secretion in Human Gingival Fibroblasts

INTRODUCTION

Gingival fibroblast-mediated extracellular matrix remodelling is implicated in the pathogenesis of periodontitis, yet the stimuli that regulate this response are not fully understood. The immunoregulatory adipokine leptin is detectable in the gingiva, human gingival fibroblasts express functional leptin receptor mRNA and leptin is known to regulate extracellular matrix remodelling responses in cardiac fibroblasts. We therefore hypothesised that leptin would enhance matrix metalloproteinase secretion in human gingival fibroblasts.

METHODS AND RESULTS

We used in vitro cell culture to investigate leptin signalling and the effect of leptin on mRNA and protein expression in human gingival fibroblasts. We confirmed human gingival fibroblasts expressed cell surface leptin receptor, found leptin increased matrix metalloproteinase-1, -3, -8 and -14 expression in human gingival fibroblasts compared to unstimulated cells, and observed that leptin stimulation activated MAPK, STAT1/3 and Akt signalling in human gingival fibroblasts. Furthermore, leptin synergised with IL-1 or the TLR2 agonist pam2CSK4 to markedly enhance matrix metalloproteinase-1 and -3 production by human gingival fibroblasts. Signalling pathway inhibition demonstrated ERK was required for leptin-stimulated matrix metalloproteinase-1 expression in human gingival fibroblasts; whilst ERK, JNK, p38 and STAT3 were required for leptin+IL-1- and leptin+pam2CSK4-induced matrix metalloproteinase-1 expression. A genome-wide expression array and gene ontology analysis confirmed genes differentially expressed in leptin+IL-1-stimulated human gingival fibroblasts (compared to unstimulated cells) were enriched for extracellular matrix organisation and disassembly, and revealed that matrix metalloproteinase-8 and -12 were also synergistically upregulated by leptin+IL-1 in human gingival fibroblasts.

CONCLUSIONS

We conclude that leptin selectively enhances the expression and secretion of certain matrix metalloproteinases in human gingival fibroblasts, and suggest that gingival fibroblasts may have an ECM-degrading phenotype during conditions of hyperleptinaemia (e.g., obesity, type 2 diabetes mellitus, exogenous leptin therapy).

Inner-membrane protein MorC is involved in fimbriae production and biofilm formation in Aggregatibacter actinomycetemcomitans

Fimbrial subunit synthesis, secretion and assembly on the surface of the periodontal pathogen Aggregatibacter actinomycetemcomitans are essential for biofilm formation. A recent quantitative proteomics study employing an afimbriated strain and a developed mutant isogenic for the inner-membrane protein morphogenesis protein C (MorC) revealed that the abundance of the proteins of the fimbrial secretion apparatus in the membrane is dependent on MorC. To investigate further the relationship between MorC and fimbriation, we identified and complemented the defect in fimbriae production in the afimbriated laboratory strain. The transformed strain expressing a plasmid containing genes encoding the WT fimbrial subunit and the prepilin peptidase displayed all of the hallmarks of a fimbriated bacterium including the distinct star-like colony morphology, robust biofilm formation, biofilm architecture composed of discrete microcolonies and the presence of fimbriae. When the identical plasmid was transformed into a morC mutant strain, the bacterium did not display any of the phenotypes of fimbriated strains. Extension of these studies to a naturally fimbriated clinical strain showed that the resulting morC mutant maintained the characteristic colony morphology of fimbriated strains. There was, however, a reduction in the secretion of fimbrial subunits, and fewer fimbriae were observed on the surface of the mutant strain. Furthermore, the morC mutant of the fimbriated strain displayed a significantly altered biofilm microcolony architecture, while maintaining a similar biofilm mass to the parent strain. These results suggest that MorC influences fimbrial secretion and microcolony formation in A. actinomycetemcomitans.

Anti-Inflammation of N-Benzyl-4-Bromobenzamide in Lipopolysaccharide-Induced Human Gingival Fibroblasts

OBJECTIVE

To evaluate the effect of N-benzyl-4-bromobenzamide (NBBA) on lipopolysaccharide (LPS)-induced IL-6 and prostaglandin E2 (PGE2) production in human gingival fibroblasts (HGFs).

MATERIAL AND METHODS

The benzamide compound was synthesized. The condition for IL-6 production of HGFs after induction with LPS was optimized. The HGFs were incubated with NBBA (10 µg/ml) for 30 min before LPS (1 μg/ml) was added. After 24 h of incubation time, the culture media were harvested and their IL-6 and PGE2 contents were determined using an enzyme-linked immunosorbent assay. Prednisolone (PDS) and NS-398 were used as positive controls. Statistical analysis of the IL-6 and PGE2 contents was performed using the ANOVA test followed by the Tukey multiple-comparisons test to compare replicate means. p < 0.001 was considered statistically significant.

RESULTS

The maximum IL-6 production was achieved when HGFs were exposed to 1 μg/ml of LPS for 24 h, which was inhibited by the IL-6 immunosuppressant PDS. The benzamide compound, NBBA, exhibited a potent anti-IL-6 activity with inhibition of 35.6 ± 0.5%, significantly different from in the LPS-induced HGFs (p < 0.001). In addition, it inhibited 75.6 ± 0.52% PGE2 production. Cell viability was not significantly affected by treatment with NBBA at a concentration <10 µg/ml (p < 0.001).

CONCLUSIONS

NBBA exhibited an inhibitory effect on the production of IL-6 and PGE2 in LPS-induced HGFs. It could serve as a compound with inhibiting inflammatory activity in periodontal disease.

uPA Attenuated LPS-induced Inflammatory Osteoclastogenesis through the Plasmin/PAR-1/Ca(2+)/CaMKK/AMPK Axis

Chronic inflammatory diseases, such as rheumatoid arthritis and periodontitis-caused bone destruction, results from an increase of bone-resorbing osteoclasts (OCs) induced by inflammation. However, the detailed mechanisms underlying this disorder remain unclear. We herein investigated that the effect of urokinase-type plasminogen activator (uPA) on inflammatory osteoclastogenesis induced by lipopolysaccharide (LPS), which is a potent stimulator of bone resorption in inflammatory diseases. We found that the uPA deficiency promoted inflammatory osteoclastogenesis and bone loss induced by LPS. We also showed that LPS induced the expression of uPA, and the uPA treatment attenuated the LPS-induced inflammatory osteoclastogenesis of RAW264.7 mouse monocyte/macrophage lineage cells. Additionally, we showed that the uPA-attenuated inflammatory osteoclastgenesis is associated with the activation of plasmin/protease-activated receptor (PAR)-1 axis by uPA. Moreover, we examined the mechanism underlying the effect of uPA on inflammatory osteoclastogenesis, and found that uPA/plasmin/PAR-1 activated the adenosine monophosphate-activated protein kinase (AMPK) pathway through Ca2+/calmodulin dependent protein kinase kinase (CaMKK) activation, and attenuated inflammatory osteoclastogenesis by inactivation of NF-κB in RAW264.7 cells. These data suggest that uPA attenuated inflammatory osteoclastogenesis through the plasmin/PAR-1/Ca2+/CaMKK/AMPK axis. Our findings may provide a novel therapeutic approach to bone loss caused by inflammatory diseases.

Theaflavins inhibit pathogenic properties of P. gingivalis and MMPs production in P. gingivalis-stimulated human gingival fibroblasts

OBJECTIVES

Theaflavins, the main polyphenols in black tea, possesses a wide range of beneficial pharmacological properties. Porphyromonas gingivalis (P. gingivalis) is a major aetiological agent associated with periodontitis, a chronic inflammatory disease affecting tooth-supporting tissues. The aim of the present study is to investigate the effect of theaflavins on pathogenic properties of P. gingivalis and on periodontitis by inhibiting matrix metalloproteinases (MMPs) production induced by this oral pathogen.

METHODS

Microplate dilution assays were performed to determine the effect of theaflavins against planktonic culture and biofilm of P. gingivalis. The effect of theaflavins on gingipain and collagenase activities of P. gingivalis was evaluated using synthetic chromogenic peptides and fluorogenic substrate. Human gingival fibroblasts (HGFs) were stimulated with P. gingivalis in the presence or absence of theaflavins, and then MMP-1, -2 secretion and their mRNA expression were assessed using an enzyme-linked immunosorbent assay (ELISA) and real-time PCR analysis, respectively.

RESULTS

Theaflavins exhibited the antimicrobial effects against both planktonic culture and biofilm of P. gingivalis. Theaflavins also markedly inhibited the proteinase activities of P. gingivalis collagenase and gingipains in a dose-dependent manner. Lastly, theaflavins significantly inhibited the secretion and mRNA expression of MMP-1 and MMP-2 by HGFs stimulated with P. gingivalis.

CONCLUSION

Theaflavins can affect the virulent properties of P. gingivalis and attenuate the MMP-mediated inflammatory response induced by this pathogen, which suggests that theaflavins may be potentially valuable supplementary therapeutic agent for prevention and treatment of P. gingivalis-associated periodontal diseases.

High-throughput proteomics using antibody microarrays: an update

Antibody-based microarrays are a rapidly emerging technology that has advanced from the first proof-of-concept studies to demanding serum protein profiling applications during recent years, displaying great promise within disease proteomics. Miniaturized micro- and nanoarrays can be fabricated with an almost infinite number of antibodies carrying the desired specificities. While consuming only minute amounts of reagents, multiplexed and ultrasensitive assays can be performed targeting high- as well as low-abundance analytes in complex nonfractionated proteomes. The microarray images generated can then be converted into protein expression profiles or protein atlases, revealing a detailed composition of the sample. The technology will provide unique opportunities for fields such as disease diagnostics, biomarker discovery, patient stratification, predicting disease recurrence and drug target discovery. This review describes an update of high-throughput proteomics, using antibody-based microarrays, focusing on key technological advances and novel applications that have emerged over the last 3 years.

Inhibitory effect of Zingiber cassumunar extracts on lipopolysaccharide-induced cyclooxygenase-2 and matrix metalloproteinase expression in human gingival fibroblasts

BACKGROUND AND OBJECTIVE

Lipopolysaccharides (LPS) induce the production of proinflammatory mediators such as prostaglandins and matrix metalloproteinases (MMPs) in human gingival fibroblasts (HGFs). Zingiber cassumunar is a medicinal plant that possesses anti-inflammatory properties. The aim of this study was to determine the effects of the Z. cassumunar extract on the expression of cyclooxygenase (COX)-1, COX-2 and MMP-2 in HGFs challenged with LPS.

MATERIAL AND METHODS

HGFs were treated with LPS in the presence or absence of Z. cassumunar extracts. The levels of expression of COX-1, COX-2 and MMP-2 mRNAs and of COX-1, COX-2 and MMP-2 proteins were detected by reverse transcription-polymerase chain reaction and western blotting, respectively. MMP-2 activities in cell-culture supernatants were determined using gelatin zymography. MAPK activation was evaluated by western blotting.

RESULTS

LPS treatment of HGFs resulted in the activation of ERK1/2, p38 and JNK. Z. cassumunar extracts significantly inhibited the phosphorylation of ERK1/2 and JNK in HGFs stimulated with LPS. A lesser inhibitory effect was observed for the phosphorylation of p38. RT-PCR and western blot analyses showed that Z. cassumunar extracts inhibited the LPS-induced expression of COX-2 mRNA and COX-2 protein, respectively, but not of COX-1 mRNA or COX-1 protein. Pretreatment of HGFs with Z. cassumunar also attenuated the induction of MMP-2 with LPS.

CONCLUSION

Our results indicate that Z. cassumunar extracts inhibit COX-2 and MMP-2 production by LPS-activated human gingival fibroblasts through blocking the proinflammatory signaling pathway involving ERK1/2, JNK and p38.

Effects of cranberry components on human aggressive periodontitis gingival fibroblasts

BACKGROUND AND OBJECTIVE

Aggressive periodontitis (AgP) causes rapid periodontal breakdown involving AgP gingival fibroblast production of cytokines [i.e. interleukin (IL)-6, a bone metabolism regulator], and matrix metalloproteinase (MMP)-3. Lipopolysaccharide upregulates fibroblast IL-6 and MMP-3, via transcription factors (i.e. NF-κB). Cranberry (Vaccinium macrocarpon) inhibits lipopolysaccharide-stimulated macrophage and normal gingival fibroblast activities, but little is known of its effects on AgP fibroblasts. Objectives of this study are to use AgP fibroblasts, to determine cytotoxicity of cranberry components or periodontopathogen (Fusobacterium nucleatum, Porphyromonas gingivalis) lipopolysaccharide ± cranberry components, and effects of cranberry components on lipopolysaccharide-stimulated NF-κB activation and IL-6 and MMP-3 production.

MATERIAL AND METHODS

AgP fibroblasts were incubated ≤ 6 d with high molecular weight non-dialyzable material (NDM) (derived from cranberry juice (1-500 μg/mL) or lipopolysaccharide (1 μg/mL) ± NDM. Membrane damage and viability were assessed by enzyme activity released into cell supernatants and activity of a mitochondrial enzyme, respectively. Secreted IL-6 and MMP-3 were measured by ELISA. NF-κB p65 was measured via binding to an oligonucleotide containing the NF-κB consensus site. Data were analyzed using analysis of variance and Scheffe's F procedure for post hoc comparisons.

RESULTS

Short-term exposure to NDM, or lipopolysaccharide ± NDM caused no membrane damage. NDM (≤ 100 μg/mL) or lipopolysaccharide ± NDM had no effect on viability ≤ 7 d exposure. NDM (50 μg/mL) inhibited lipopolysaccharide-stimulated p65 (P ≤ 0.003) and constitutive or lipopolysaccharide-stimulated MMP-3 (P ≤ 0.02). NDM increased AgP fibroblast constitutive or lipopolysaccharide-stimulated IL-6 (P ≤ 0.0001), but inhibited normal human gingival fibroblast IL-6 (P ≤ 0.01).

CONCLUSION

Lack of toxicity of low NDM concentrations, and its inhibition of NF-κB and MMP-3, suggest that cranberry components may regulate AgP fibroblast inflammatory responses. Distinct effects of NDM on AgP and gingival fibroblast production of IL-6 (which can have both positive and negative effects on bone metabolism) may reflect phenotypic differences in IL-6 regulation in the two cell types.

Cyclosporine-A inhibits MMP-2 and -9 activities in the presence of Porphyromonas gingivalis lipopolysaccharide: an experiment in human gingival fibroblast and U937 macrophage co-culture

BACKGROUND AND OBJECTIVE

Studies have shown that bacterial plaque and the associated gingival inflammation increase the severity of gingival overgrowth induced by cyclosporine-A (CsA). This in vitro study aimed to evaluate the effect of CsA on the activities of MMPs from the co-culture of human gingival fibroblasts and U937 macrophages in the presence or absence of Porphyromonas gingivalis lipopolysaccharide (LPS).

MATERIAL AND METHODS

Activities of pro-MMP-2, MMP-2 and pro-MMP-9 in the supernatants of independent cultures and co-cultures were examined by zymography. RT-PCR was selected to evaluate the expression of mRNA for membrane type-1 (MT1) MMP in the co-cultures.

RESULTS

Activities of MMPs in the co-cultures were significantly greater when compared with any of the independent cultures. Lipopolysaccharide significantly increased the MMP activities in a dose-dependent manner in the co-cultures, whereas CsA inhibited these activities. In the presence of both CsA and LPS, the MMP activities inhibited by CsA could still be observed in the co-cultures. In the individual cultures, in contrast, the CsA-inhibited MMP activities, in the presence of LPS, were minimally detected. The mRNA expression of MT1-MMP was significantly enhanced after LPS treatment; however, this enhancement was inhibited by CsA.

CONCLUSION

This study demonstrated that, in co-cultures of human gingival fibroblasts and U937 macrophages, CsA could inhibit MMP activities in the presence of P. gingivalis LPS. It might be part of the underlying reason for the persistent overgrowth of gingiva seen when bacterial plaque and local inflammation are present during CsA therapy.

Matrix metalloproteinase-1 of gingival fibroblasts influenced by advanced glycation end products (AGEs) and their association with receptor for AGEs and nuclear factor-κB in gingival connective tissue

BACKGROUND

The effect of advanced glycation end products (AGEs) on gingival inflammation has not been fully elucidated. This study aims to investigate the hypothesis that AGEs may enhance the expression of matrix metalloproteinase-1 (MMP-1) of human gingival fibroblasts (HGFs) and to explore whether the signal pathway receptor for AGE (RAGE)/nuclear factor-κB (NF-κB) are involved in the expression of MMP-1 in HGFs.

METHODS

Cultured HGFs from 12 healthy gingival human tissue samples were coincubated with AGEs for the detection of MMP-1 protein and mRNA. Thirty-six gingival samples were collected and treated for the determination of RAGE, NF-κB, and MMP-1 mRNA level in gingival connective tissues from the participants with chronic periodontitis, diabetes-associated periodontitis, and healthy controls. Enzyme-linked immunosorbent assay and real-time fluorescence reverse transcription-polymerase chain reaction were used for the measurement of protein and mRNA level, respectively. In addition, clinical periodontal parameters were also checked.

RESULTS

AGEs strongly induced MMP-1 mRNA and protein expression in HGFs and in a time- and concentration-dependent manner (P <0.05). In gingival connective tissue, the level of both RAGE mRNA and NF-κB mRNA were higher in patients with periodontitis than in healthy controls (P <0.05). There was significant correlation between the level of RAGE mRNA and NF-κB mRNA (R(2) = 0.90, P <0.05).

CONCLUSIONS

Accumulation of AGEs may upregulate the expression of MMP-1 by HGFs, which may play a role in the development of diabetes-associated periodontitis, and RAGE/NF-κB pathway may be involved in metabolism of MMP-1 in HGFs.

[Pathogenesis of parodontitis in rheumatic diseases]

Inflammatory periodontal disease (PD) is a common disease worldwide that has a primarily bacterial aetiology and is characterized by dysregulation of the host inflammatory response. The degree of inflammation varies among individuals with PD independently of the degree of bacterial infection, suggesting that alteration of the immune function may substantially contribute to its extent. Factors such as smoking, education, and body mass index (BMI) are discussed as potential risk factors for PD. Most PD patients respond to bacterial invaders by mobilizing their defensive cells and releasing cytokines such as interleukin (IL)-1beta, tumour necrosis factor (TNF)-alpha, and IL-6, which ultimately causes tissue destruction by stimulating the production of collagenolytic enzymes, such matrix metalloproteinases. Recently, there has been growing evidence suggesting an association between PD and the increased risk of systemic diseases, such ateriosclerosis, diabetes mellitus, stroke, and rheumatoid arthritis (RA). PD and rheumatologic diseases such as RA share many pathological aspects and immunological findings.

Vaginal and oral microbes, host genotype and preterm birth

Preterm birth (PTB) is a leading cause of infant mortality and morbidity in the US and across the globe. Infection and associated inflammation are important initiators for PTB pathways; an estimated 40% of PTBs are attributed to amniochorionic-decidual or systemic inflammation. Historically, intrauterine infections have been implicated in PTB; recent evidence suggests that infections remote from the fetal site may also be causative. There is strong epidemiological evidence that bacterial vaginosis and periodontitis--two syndromes characterized by perturbations in the normal vaginal and oral bacterial microflora, respectively--are linked to infection-associated PTB. Oral and vaginal environments are similar in their bacterial microbiology; identical bacterial species have been independently isolated in periodontitis and bacterial vaginosis. Periodontitis and bacterial vaginosis also share many behavioral and sociodemographic risk factors suggesting a possible common pathophysiology. Genetic polymorphisms in host inflammatory responses to infection are shared between bacterial vaginosis, periodontitis and PTB, suggesting common mechanisms through which host genotype modify the effect of abnormal bacterial colonization on preterm birth. We review the state of knowledge regarding the risk of PTB attributable to perturbations in bacterial flora in oral and vaginal sites and the role of host genetics in modifying the risk of infection-related PTB. We posit that bacterial species that are common in perturbed vaginal and oral sites are associated with PTB through their interaction with the host immune system.

Advanced glycation end products inhibit the expression of collagens type I and III by human gingival fibroblasts

BACKGROUND

It is evident that diabetes and periodontal disease are closely interrelated. Accumulation of advanced glycation end products (AGEs), coupled with exaggerated host responses to bacterial infection, may account for the increased periodontal destruction observed in patients with uncontrolled diabetes. The present study investigated the effects of AGEs on the viability of human gingival fibroblasts (HGFs) and the expression of types I and III collagen in HGFs.

METHODS

The cell viability of HGFs was examined by methylthiazolet-etrazolium assay, whereas the expression of types I and III collagen message and protein was detected by real-time quantitative reverse transcription-polymerase chain reaction and sandwich enzyme-linked immunosorbent assay, respectively.

RESULTS

AGEs significantly suppressed the cell viability of HGFs from 24 to 72 hours (P <0.01). A high concentration of glucose (25 mmol/l) in the culture media exaggerated the inhibition of the survival rate of HGFs (P <0.01). The expression of collagen types I and III messages and proteins was significantly downregulated at 72 hours by AGEs in a concentration-dependent manner (P <0.05). Moreover, the synthesis of intracellular types I and III collagen protein was markedly inhibited by AGEs (P <0.05).

CONCLUSIONS

AGEs may suppress the cell viability of HGFs and downregulate the expression of types I and III collagen by the cells. Further investigations are warranted to clarify the molecular mechanisms of AGEs in the regulation of cell function and collagen metabolism in patients with diabetes and periodontitis.

Tetracyclines and chemically modified tetracycline-3 (CMT-3) modulate cytokine secretion by lipopolysaccharide-stimulated whole blood

In addition to their bacteriostatic effect, tetracyclines, which are often used in the treatment of periodontitis, also present anti-inflammatory properties. In the present study, we investigated the effects of tetracycline (TC), doxycycline (doxy), and chemically modified tetracycline-3 (CMT-3) on the production of pro-inflammatory mediators and matrix metalloproteinases (MMPs) in an ex vivo human whole blood (WB) model stimulated with Porphyromonas gingivalis lipopolysaccharide (LPS). WB samples obtained from three periodontitis patients and six healthy subjects were stimulated with P. gingivalis LPS in the absence and presence of TC, doxy, or CMT-3. The secretion of interleukin-1beta (IL-1beta), interleukin-6 (IL-6), interleukin-8 (IL-8), MMP-8, and MMP-9 by the WB samples was determined using enzyme-linked immunosorbent assays. P. gingivalis LPS significantly increased the secretion of all cytokines and MMPs tested. While we observed inter-patient variations, TC, doxy, and CMT-3 caused reductions of LPS-induced cytokine secretion to various degrees. TC, doxy, and CMT-3 had no significant effect on MMP-8 and MMP-9 secretion by LPS-stimulated WB samples. In conclusion, we used a human WB model that takes into consideration relevant in vivo immune cell interactions in the presence of plasma proteins to show that TC, doxy, and CMT-3 can reduce the production of pro-inflammatory mediators. This property may contribute to the clinically proven benefits of these molecules in the treatment of periodontitis and other chronic inflammatory diseases.

Antibody-based microarrays

Antibody-based microarrays are a new powerful proteomic technology that can be used to generate rapid and detailed expression profiles of defined sets of protein analytes in complex samples as well as high-resolution portraits of entire proteomes. Miniaturized micro- and nanoarrays can be printed with numerous antibodies carrying the desired specificities. Multiplexed and ultra-sensitive assays, specifically targeting several analytes in a single experiment, can be performed, while consuming only minute amounts of the sample. The array images generated can then be converted into protein expression profiles, or maps, revealing the detailed composition of the sample. This promising proteomic research tool will thus provide unique opportunities for e.g. disease proteomics, biomarker discovery, disease diagnostics, and patient stratification. This review describes the antibody-based microarray technology and applications thereof.

Actinobacillus actinomycetemcomitans lipopolysaccharide stimulates collagen phagocytosis by human gingival fibroblasts

INTRODUCTION

Collagen phagocytosis by fibroblasts is involved in the intracellular pathway related to collagen breakdown in soft connective tissues. The possible role of lipopolysaccharide (LPS) in regulating this fibroblast function has not been elucidated so we investigated the effect of LPS from Actinobacillus actinomycetemcomitans, a periodontopathic bacterium, on collagen phagocytic activity in human gingival fibroblasts and associated regulatory mechanisms.

METHODS

LPS pretreatment stimulated binding of collagen-coated beads to cells and, subsequently, their internalization.

RESULTS

The LPS-activated collagen phagocytic process was enhanced in the presence of the soluble form of CD14 (sCD14) or LPS-binding protein (LBP), while the LPS/LBP treatment activated Akt and induced actin reorganization. Furthermore, these LPS/LBP-induced effects were partially suppressed by adding phosphatidyl-inositol-3 kinase (PI3K) inhibitors.

CONCLUSION

These results suggest that A. actinomycetemcomitans LPS disturbs the homeostasis of collagen metabolism within gingival tissue by facilitating collagen phagocytosis by gingival fibroblasts, and serum sCD14 and LBP positively regulate the action of LPS. In addition, the PI3K/Akt signaling is thought to partially mediate the LPS/LBP-stimulated collagen phagocytic pathway, which may be dependent on actin cytoskeletal rearrangement.

Beyond good and evil in the oral cavity: insights into host-microbe relationships derived from transcriptional profiling of gingival cells

In many instances, the encounter between host and microbial cells, through a long-standing evolutionary association, can be a balanced interaction whereby both cell types co-exist and inflict a minimal degree of harm on each other. In the oral cavity, despite the presence of large numbers of diverse organisms, health is the most frequent status. Disease will ensue only when the host-microbe balance is disrupted on a cellular and molecular level. With the advent of microarrays, it is now possible to monitor the responses of host cells to bacterial challenge on a global scale. However, microarray data are known to be inherently noisy, which is caused in part by their great sensitivity. Hence, we will address several important general considerations required to maximize the significance of microarray analysis in depicting relevant host-microbe interactions faithfully. Several advantages and limitations of microarray analysis that may have a direct impact on the significance of array data are highlighted and discussed. Further, this review revisits and contextualizes recent transcriptional profiles that were originally generated for the specific study of intricate cellular interactions between gingival cells and 4 important plaque micro-organisms. To our knowledge, this is the first report that systematically investigates the cellular responses of a cell line to challenge by 4 different micro-organisms. Of particular relevance to the oral cavity, the model bacteria span the entire spectrum of documented pathogenic potential, from commensal to opportunistic to overtly pathogenic. These studies provide a molecular basis for the complex and dynamic interaction between the oral microflora and its host, which may lead, ultimately, to the development of novel, rational, and practical therapeutic, prophylactic, and diagnostic applications.

Influence of aging on biological properties of periodontal ligament cells

The majority of patients eligible for periodontal regenerative therapies are aged subjects. Since periodontal ligament cells (PDLC) are essential for periodontal regeneration, the aim of the present study was to determine the effect of cellular aging on PDLC, including genes associated with extracellular matrix metabolism and growth-associated factors. PDLC cultures were obtained from subjects aged 15 to 20 years and subjects aged more than 60 years. Proliferation, cell viability, mineralization assays, and mRNA levels were assessed for type I and III collagen, platelet-derived growth factor (PDGF)-1, basic fibroblast growth factor (bFGF), metalloproteinase (MMP)-2 and-8, and tissue inhibitor of metalloproteinases (TIMP)-1 and-2. Data analysis demonstrated that aging negatively influenced cell proliferation and mineral nodule formation (p < 0.05). Gene expression analysis further showed that mRNA levels for bFGF, PDGF-1, and TIMP-2 were not affected by aging (p > 0.05). In addition, mRNA levels for type I and III collagen were significantly lower in aged cells (p < 0.05), whereas MMP-2 and-8 and TIMP-1 mRNA levels were higher (p < 0.05). Within the limits of the present study, data analysis suggests that aging modulates important biological properties of periodontal ligament cells, diminishes the potential for mineral nodule formation, and favors extracellular matrix degradation.

N-acetylcysteine prevents LPS-induced pro-inflammatory cytokines and MMP2 production in gingival fibroblasts

Periodontitis is an inflammatory process that ultimately results in tooth loss. Although the primary etiologic agent for periodontitis is bacteria, the majority of periodontal tissue destruction is thought to be caused by an inappropriate host response. Reactive oxygen species (ROS) have been known to be involved in periodontal tissue destruction. We treated human gingival fibroblasts with lipopolysaccharide (LPS) obtained from E. coli and the periodontopathogens Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis, and examined their inflammatory responses in the presence and absence of the antioxidant N-acetylcysteine (NAC). LPS enhanced ROS production, as well as, expression of pro-inflammatory cytokines such as interleukin-1beta, interleukin-6, interleukin-8 and tumor necrosis factor-alpha, and the production and activation of MMP2. NAC suppressed all LPS-induced inflammatory responses examined, suggesting that LPS-induced ROS may play a major regulatory role in these responses in gingival fibroblasts. In addition, NAC prevented LPS-induced activation of p38 MAPK and JNK but not phosphorylation and subsequent degradation of IkB. These results indicate that NAC exerts anti-inflammatory effects in LPS-stimulated gingival fibroblasts, functioning at least in part via down-regulation of JNK and p38 MAPK activation. Furthermore, this work suggests that antioxidants may be useful in adjunctive therapies that complement conventional periodontal treatments.