Influence of titanium ions on cytokine levels of murine splenocytes stimulated with periodontopathic bacterial lipopolysaccharide

PURPOSE

Titanium (Ti) is frequently used in dental implants because of its excellent corrosion resistance, mechanical properties, and biocompatibility. However, Ti ions may be slowly released as a result of corrosion, contributing to peri-implantitis, a major cause of dental implant failure. This study examined the influence of Ti ions on cytokine levels in murine splenocytes, an immunocompetent cell type, stimulated with Aggregatibacter actinomycetemcomitans lipopolysaccharide (LPS) and the influence of Ti ions on splenocyte viability.

MATERIALS AND METHODS

Splenocytes were prepared from 5- to 10-week-old male C57BL/6 mice and BALB/c mice. Cytokine levels in culture supernatants from murine splenocytes stimulated with A actinomycetemcomitans LPS were determined with enzyme-linked immunosorbent assay. A tetrazolium salt assay was carried out to evaluate the cytotoxicity of Ti ions against murine splenocytes.

RESULTS

The present study demonstrated that Ti ions influence cytokine levels in LPS-stimulated splenocytes. Significantly higher values (P < .05) were observed for interleukins 1β, 6, and 10; interferon-γ; tumor necrosis factor alpha; and granulocyte macrophage colony-stimulating factor in the culture supernatants of LPS-stimulated splenocytes of both mouse strains in the presence of Ti ions, as compared to the absence of Ti ions. Tetrazolium salt assay confirmed that the Ti ions used in this study did not affect the viability of murine splenocytes.

CONCLUSION

This study suggests that Ti ions enhanced cytokine production induced by periodontopathic bacterial LPS.

[Comparison of the effects of Ginkgo biloba extract and minocycline hydrochlovide on periodontitis]

OBJECTIVE

To compare the clinical effect of Ginkgo biloba extract gel (Ginkgo biloba extract,EGB) and minocycline hydrochloride (Periocline) on periodontitis and their inhibition on putative periodontal pathogens.

METHODS

Thirty patients with moderate-to-severe periodontitis were selected. The patients were divided into an experimental group and a positive control group (minocycline hydrochloride). Supragingival and subgingival scaling were performed on all patients. Subgingival plaque samples were collected before treatment, 1 week, 2 months and 4 months after treatment. The four major periodontal pathogens Porphyromonas gingivalis (Pg), Bacteroides forsythus (Bf), Prevotella intermedia (Pi), Treponema denticola (Td) were detected by polymerase chain reaction. Clinical indexes plaque index (PLI), bleeding index (BI) and probing depth (PD), attachment loss (AL) were examined before treatment, 3 months and 6 months after treatment. The results were statistically analyzed.

RESULTS

The detection rates of the 4 periodontal pathogens were Td (83.3%), Tf (95.0%), Pi (80.0%), Pg (81.7% ) in experimental group and Td (83.3%), Tf (95.0%), Pi (80.0%), Pg (81.7%) in control group before treatment. The detection rates in experimental group were not significantly different with those in control group after treatment, except for the detection rate of Pg 1 week after treatment (P < 0.01, the detection of Pg was 56.7% in experimental group and 53.3% in control group 1 week after treatment). The PLI and BI were not significantly different between experimental group and control group after treatment (P > 0.05). The difference was statistically significant at 6 months after treatment [(3.5 ± 0.5) mm for experimental group and (3.2 ± 0.4) mm for control group, P = 0.00]. The mean of AL decreased with time. The difference was statistically significant at 6 months after treatment [ (4.5 ± 0.4) mm for experimental group and (4.3 ± 0.4) mm for control group at 6 months, P = 0.01].

CONCLUSIONS

The inhibition effects of EGB and minocycline hydrochloride were comparable for major periodontal pathogens within short term.

Simvastatin inhibits LPS-induced alveolar bone loss during metabolic syndrome

Studies in recent years have shown a positive relationship between metabolic syndrome (MS) and periodontal disease (PD). Given that patients with MS take statins to reduce cholesterol, and statins also have anti-inflammatory effects, it is important to determine if statin intake hinders the progression of MS-associated PD. In this study, PD was induced in Zucker fat rats (ZFRs), an animal model for MS, and in control lean rats by periodontal injection of Aggregatibacter actinomycetemcomitans lipopolysaccharide (LPS), while simvastatin was given to some of the rats via gavage. After 4 wk of treatment, alveolar bone loss was determined by micro-computed tomography. To explore the underlying mechanisms, we determined the effect of simvastatin on tissue inflammation and the expression of molecules involved in osteoclastogenesis. Results showed that while bone loss was increased by LPS in both ZFRs and the control lean rats, it was significantly more in the former than the latter. Simvastatin effectively alleviated bone loss in both ZFRs and the control rats. Results also showed that LPS stimulated leukocyte tissue infiltration and expression of molecules for osteoclastogenesis, but simvastatin significantly modulated the stimulation. This study demonstrated that simvastatin inhibited LPS-induced alveolar bone loss and periodontal tissue inflammation in rats with MS.

Inhibitory activity of Myrtus communis oil on some clinically isolated oral pathogens

OBJECTIVES

To determine the antimicrobial activities of Myrtus communis oil (MCO) on some oral pathogens.

MATERIAL AND METHODS

Thirty strains of Streptococcus mutans, Aggregatibacteractinomycetemcomitans, Porphyromonas gingivalis and 20 strains of Streptococcus pyogenes and Candida albicans isolated from patients with dental caries, periodontal diseases, pharyngitis and oral lesions associated with artificial dentures were used for the antimicrobial activity of MCO. The oil was prepared by hydrodistillation procedures using a Clevenger apparatus. Agar disk diffusion and broth microdilution methods were performed on various concentrations of MCO (3.9-1,000 µg/ml) using all the pathogens isolated.

RESULTS

All isolates were sensitive to MCO at 125-1,000 µg/ml by agar disk diffusion producing inhibition zones of 8.1-41.25 mm in diameter. All of the S. pyogenes, S. mutans and C. albicans strains were sensitive to 62.5 µg/ml while 70% (21/30) of A. actinomycetemcomitans and 66.6% (20/30) of P. gingivalis were resistant to these concentrations. All S. pyogenes and S. mutans strains were sensitive to 31.25 µg/ml. All S. pyogenes strains were sensitive to 15.6 and 7.8 µg/ml of MCO. None of the clinical isolates in this study were sensitive to 3.9 µg/ml or to a lower concentration of oil. The minimum inhibitory concentrations of MCO for S. pyogenes, S. mutans, C. albicans, A.actinomycetemcomitans and P. gingivalis were 29.68 ± 4.8, 31.25 ± 0, 46.9 ± 16, 62.5 ± 0 and 62.5 ± 0 µg/ml, respectively.

CONCLUSIONS

Data obtained in this study revealed a strong antimicrobial activity of MCO on the tested oral pathogens, and MCO could therefore be useful in the prevention of the related oral infections.

[Different expression of cytokines induced by Actinobacillus actinomycetemcomitans lipopolysaccharide in monocytes/macrophages from different organs of rabbits]

OBJECTIVE

To investigate the expression of cytokines induced by Actinobacillus actinomycetemcomitans lipopolysaccharide (Aa-LPS) in monocytes/macrophages from different organs of rabbits.

METHODS

The peripheral mononuclear cells (Mo), alveolar macrophages (AM), peritoneal macrophages (PM) and Kupffer cells (KC) from five New Zealand rabbits were isolated respectively. Then the cells from different organs were stimulated with Escherichia coli (Ec)-LPS or Aa-LPS at the dose of 1 mg/L. After culture for 24 hours, the expression of tumor necrosis factor-α (TNF-α), interleukin (IL)6, IL-1β, IL-8 mRNA and protein were determined by real-time PCR and enzyme-linked immunosorbent assay respectively.

RESULTS

The monocytes/macrophages challenged by Ec-LPS or Aa-LPS expressed more cytokines both in mRNA and protein levels compared with the controls (P < 0.05). Among them, AM displayed the highest respond when encount with Aa-LPS, with the TNF-α, IL-6, IL-1β, IL-8 mRNA relative levels were (0.4719 ± 0.0171), (2.7895 ± 0.0669), (5.1527 ± 0.1190), (3.6785 ± 0.1836) and the proteins concentrations were (82.2 ± 5.4), (40.2 ± 2.0), (50 308.3 ± 445.0), (35 305.3 ± 1480.9) ng/L respectively. And the inducibility of Aa-LPS was stronger than that of Ec-LPS (P < 0.05). Meanwhile the cells from different organs showed discrepant response when exposed to Aa-LPS (P < 0.05). The results showed their abilities to secrete cytokines were in the sequence of AM > Mo > KC > PM.

CONCLUSIONS

Aa-LPS influenced the expression of cytokines in monocytes/macrophages from different organs of rabbits.

Membrane fusion proteins of type I secretion system and tripartite efflux pumps share a binding motif for TolC in gram-negative bacteria

The Hly translocator complex of Escherichia coli catalyzes type I secretion of the toxin hemolysin A (HlyA). In this complex, HlyB is an inner membrane ABC (ATP Binding Cassette)-type transporter, TolC is an outer membrane channel protein, and HlyD is a periplasmic adaptor anchored in the inner membrane that bridges HlyB to TolC. This tripartite organization is reminiscent of that of drug efflux systems such as AcrA-AcrB-TolC and MacA-MacB-TolC of E. coli. We have previously shown the crucial role of conserved residues located at the hairpin tip region of AcrA and MacA adaptors during assembly of their cognate systems. In this study, we investigated the role of the putative tip region of HlyD using HlyD mutants with single amino acid substitutions at the conserved positions. In vivo and in vitro data show that all mutations abolished HlyD binding to TolC and resulted in the absence of HlyA secretion. Together, our results suggest that, similarly to AcrA and MacA, HlyD interacts with TolC in a tip-to-tip manner. A general model in which these conserved interactions induce opening of TolC during drug efflux and type I secretion is discussed.

[Expression of tumor necrosis factor in placenta tissue of pregnant rats with chronic peridontitis]

OBJECTIVE

To examine the expression of tumor necrosis factor in placenta of pregnant rats with chronic periodontitis.

METHODS

Twenty Wistar female rats were randomly divided into two groups, control (n = 8) and experimental group (n = 12). The periodontitis model was established in the experimental group. The females and males in the two groups got together four weeks later. Nineteen days after pregnancy all rats were executed and placenta collected. The delivery time and neonatal birth weight were recorded and the pathological changes of periodontal tissue observed. Tumor necrosis factor (TNF) expression was examined in placenta by real-time quantitative polymerase chain reaction analysis.

RESULTS

The animal model of chronic periodontitis was successfully established. Experimental group delivered 30 offspring and the control group 56 offspring. The average number of pups born alive per litter in experimental group (4.1 ± 2.2) was significantly lower than that in control group (9.2 ± 2.2), P < 0.05. The birth weight of pups in experimental group [(5.01 ± 0.43) g] was significantly lower than that in the control group [(5.79 ± 0.53) g], P < 0.05. The relative quantitative expression of TNF was (1.807 ± 0.265) in experimental group the and (1.003 ± 0.021) in the control group (P = 0.001).

CONCLUSIONS

Chronic periodontitis may be related to preterm low birth weight.

[Study of putative periodontal pathogens colonies in type 2 diabetes with chronic periodontitis]

PPURPOSE: To study the permanent planting of periodontal pathogens in the subgingival plaque of periodontitis patients with type 2 diabetes, and evaluate role of periodontal pathogens in chronic periodontitis and type 2 diabetes.

METHODS

One hundred and twenty subgingival plaque samples were collected from 90 severe periodontitis and 30 healthy periodontium patients with type 2 diabetes. Porphyromonas gingivalis (Pg), Aggregatibacer actinomycetemcomitans (Aa), Fusobacterium nucleatum (Fn), Prevotella intermedia (Pi), Tannerella forsythia (Tf) and Treponema denticola (Td) were taken as aim pathogens, polymerase chain reaction (PCR) detection was used to determine the prevalence of Pg, Aa, Fn, Pi, Tf, Td in the subgingival plaque samples.The average gradation(AVG)of positive band in the agarose gel electrophoresis was analyzed to determine the proportion of Pg, Aa, Fn, Pi, Tf, Td in the subgingival plaque. Chi-square test, t test and Pearson correlation were used to analyze the relationship between the periodontal pathogens and blood glucose and blood lipid.

RESULTS

The level of triglyceridey(TC) in Tf positive subjects was significantly higher than that in Tf negative subjects, the proportion of Tf in subgingival plaque was positively correlated with the value of fasting blood glucose(FBG). The proportion of Pg was positively correlated with the level of TC. The proportion of Pi was negatively correlated with the value of FBG and TC.

CONCLUSION

Type 2 diabetes can affect the permanent planting of some putative periodontal pathogens. Supported by National"11th Five Year" Science and Technology Supporting Project (Grant No. 2007BAI18B02) and Science and Technology Research Plan of Liaoning Province(Grant No. 2007225007).

Anti-phosphorylcholine-opsonized low-density lipoprotein promotes rapid production of proinflammatory cytokines by dendritic cells and natural killer cells

BACKGROUND AND OBJECTIVE

Epidemiological and animal studies suggest that periodontal infections increase atherosclerosis risk. Periodontitis patients have elevated levels of anti-phosphorylcholine (anti-PC) reactive not only with numerous periodontal organisms but also with minimally modified low-density lipoprotein (mmLDL). Dendritic cells (DCs) reside in arterial walls and accumulate in atherosclerotic lesions. The ability of anti-PC to bind mmLDL prompted the hypothesis that opsonized mmLDL would stimulate DCs and enhance the production of proinflammatory cytokines that promote atherogenic plaque development.

MATERIAL AND METHODS

Monocyte-derived DCs (mDCs) were generated using granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-4, then stimulated with mmLDL or with anti-PC-opsonized mmLDL. The anti-PC effect was determined using flow cytometry, cofocal microscopy and cytokine assays. The production of CD83, IL-12p35 mRNA, IL-12p40 mRNA, IL-12p70 and IL-10 by DCs was monitored.

RESULTS

Dendritic cells stimulated with mmLDL expressed little CD83 and produced little IL-12p70. However, anti-PC-opsonized mmLDL enhanced DC maturation, as indicated by upregulated CD83 and rapid (≤ 48 h) production of IL-12p70 if a source of interferon-γ (IFN-γ) was available. In leukocyte cultures, natural killer (NK) cells rapidly produced IFN-γ (≤ 48 h) when interacting with IL-12-producing DCs activated by anti-PC-opsonized mmLDL. Moreover, IFN-γ promoted DC IL-12 responses that were further augmented when mmLDL was opsonized with anti-PC.

CONCLUSION

Minimally modified LDL-stimulated DCs and NK cells were mutually stimulatory, with DC IL-12p70 needed by NK cells and with NK cell IFN-γ needed by DCs. Moreover, production of these proinflammatory cytokines was markedly enhanced when LDL was opsonized by anti-PC. In short, the data suggest that the elevated anti-PC levels in periodontitis patients could promote a mechanism that facilitates atherosclerosis.

[Study on the counting of Streptococcus mutans, Streptococcus sanguis, Haemophilus actinomycetemcomitans by methyl thiazolyl tetrazolium colorimetric method]

OBJECTIVE

To explore the feasibility of methyl thiazolyl tetrazolium (MTT) colorimetric method and the applied condition for the normal bacteria in the mouth, as Streptococcus mutans (S. mutans), Streptococcus sanguis (S. sanguis), Haemophilus actinomycetemcomitans (H. actinomycetemcomitans).

METHODS

Colony forming units (CFU) which was the standard antitheses was used to count bacteria. This study would gain some parameters by changing wavelength, reactive time, dosage and so on. MTT colorimetric method was applied in the counting of S. mutans, S. sanguis and H. actinomycetemcomitans.

RESULTS

When counting S. mutans, the best wavelength was 510 nm, the best range was 1.5 x 10(5) - 1.0 x 10(7) CFU x mL(-1). When counting S. sanguis, the best wavelength was 545 nm, the best range was 1.5 x 10(5) - 2.0 x 10(7) CFU x mL(-1). When counting H. actinomycetemcomitans, the best wavelength was 557 nm, the best range was 1.0 x 10(6) - 5.0 x 10(7) CFU x mL(-1). MTT colorimetric method can be used for different aged S. mutans, S. sanguis and H. actinomycetemcomitans.

CONCLUSION

Oral bacteria could be counted by MTT colorimetric method, which is fast and convenient.

[The effect of B lymphocytes on immune response of periodontal bacteria and osteoclast differentiated reactor-RANKL expression]

PURPOSE

To study whether B lymphocytes involve in bone resorption in periodontal disease by evaluating RANKL expression of B lymphocytes in immune response to aggregatibacter actinomycetemcomitans (Aa).

METHODS

The expression of mRNA transcripts involved in day 1 and day 7 responses of cytokines in cultured rat splenocytes was determined by RT-PCR; The percentage of RANKL-expressing IgG positive cells by B cells in cultured rat splenocytes was measured by flow cytometry; and B lymphocytes capacity for induction of osteoclast differentiation was evaluated by TRAP staining. SPSS 10.0 software package was used for statistical analysis.

RESULTS

The expression of IL-4 and IL-10 in cultured cells was not changed in the presence of Aa on day 1, after culture for 7 days; The percentage of B lymphocytes, all RANKL mRNA transcripts and percentage of RANKL-expressing IgG positive cells were significantly increased in the presence, compared to the absence of Aa. These increases were considerably greater in cells isolated from immunized than non-immunized rats. B cells from Aa immunized rats significantly increased induction of osteoclast differentiation (P<0.01), and addition of human OPG-Fc into the culture significantly inhibited its induction (P<0.05), and was RANKL-independent.

CONCLUSION

B lymphocytes contribute to bone resorption in periodontal disease through involving in the immune response to Aa, up-regulation of RANKL expression and increasing induction of osteoclast differentiation.

[Preliminary study on the discrimination of putative periodontal pathogens with a metabonomics method]

OBJECTIVE

To evaluate the feasibility of identifying oral pathogenic bacteria by comparing the metabolic profiling of putative periodontal pathogens and try to find a convenient and rapid way to discriminate oral microorganisms.

METHODS

Suspensions of Porphyromonas gingivalis, Prevotella intermedia and Fusobacterium nucleatum with same density were prepared and cultured respectively at liquid BHI medium. Then the growth quantity was measured periodically through turbidimetry and the growth curves of the inoculated bacteria were completed. The culture solutions of stable growth phase were sampled and characterized by 1H-nuclear magnetic resonance 1H-NMR). The data of 1H-NMR spectroscope results were analyzed by principal components analysis (PCA).

RESULTS

The PCA showed the obvious clustering phenomena and the points of three groups differentially centralized to three clusters. Therefore, the NMR-based metabonomics profiles could discriminate the three different kinds of bacteria.

CONCLUSION

The metabonomics is a potential classable method to identify the oral pathogenic bacteria.

Chemokines gene expression of RAW 264.7 cells by Actinobacillus actinomycetemcomitans lipopolysaccharide using microarray and RT-PCR analysis

Actinobacillus actinoinycetemcomitans (A. actinomycetem-comitans) is an important pathogen casuing aggressive periodontitis. The present study was designed to investigate the chemokines expression regulated by A. actinomycetemcomitans lipopolysaccharide (LPS). Chemokines genes expression profiling was performed in Raw 264.7 cells by analyses of microarray and reverse transcription-polymerase chain reaction (RT-PCR). Microarray results showed that the induction of monocyte chemoattractant protein-1alpha (MCP-1alpha) and macrophage inflammatory protein-1alpha (MIP-1alpha), MIP-1beta, MIP-1gamma, regulated upon activation, normal T-cell expressed and secreted (RANTES), macrophage inflammatory protein-2 (MIP-2), and interferon-gamma inducible protein 10 (IP 10) by A. actinomycetemcomitans LPS was increased to 12.5, 1.53, 9.09, 17.3, 2.82, 16.1, and 18.1 folds at 18 h, respectively. To check these chemokines expression by A. actinomycetemcomitans LPS, we examined gene expressions by RT-PCR, and found that the expression of MIP-1beta, MIP-1gamma, RANTES, MIP-2, and IP 10 was increased 107.1, 93.6, 106.8, 86.5, and 162.0 folds at 18 h, respectively. These results indicate that A. actinomycetemcomitans LPS stimulates the several chemokines expressions (MIP-1alpha, MIP-1beta, MIP-1gamma, RANTES, MIP-2, and IP 10) in Raw 264.7 cells.

[Study of adherence of periodontal pathogens to collagen-treated hydroxyapatite]

OBJECTIVE

The ability of oral bacteria to adhere to tooth surface is associated with their pathogenicity. The objective of this study was to compare the ability of 4 strains of periodontal pathogens attaching to collagen-treated hydroxyapatite (C-HA) beads in order to evaluate the ability of the main periodontal pathogens to form the biofilm on root surface.

METHODS

The binding amount and binding percentage of 4 strains to C-HA were measured and compared by 3H-labeled binding assay. 4 strains of periodontal pathogens were Fusobacterium nucleatum (F. nucleatum) ATCC 10953, Porphyrin gingivalis (P. gingivalis) ATCC 33277, Prevotella intermedia (P. intermedia) ATCC 25611 and Hemophilic actinomycetemcomitans (H. actinomycetemcomitans) ATCC 29523.

RESULTS

The differences of the percentage of relative adherence between F. nucleatum ATCC 10953 and P. gingivalis ATCC 33277, as well as between H. actinomycetemcomitans ATCC 29523 and P. intermedia ATCC 25611 could not be observed. However, the percentage of relative adherence of F. nucleatum ATCC 10953 and P. gingivalis ATCC 33277 was higher than that of P. intermedia ATCC 25611 and H. actinomycetemcomitans ATCC 29523 (P<0.001), no matter cultured 24 h or 48 h. No significant difference of the percentage of the relative adherence of each stain between 24 h and 48 h cultured time could be found.

CONCLUSION

F. nucleatum and P. gingivalis exhibited strong binding ability to C-HA. Their adherence to root surface may play an important role in their local aggregation, biofilm formation during the development and recurrence of the periodontitis.

A dominant function of p38 mitogen-activated protein kinase signaling in receptor activator of nuclear factor-kappaB ligand expression and osteoclastogenesis induction by Aggregatibacter actinomycetemcomitans and Escherichia coli lipopolysaccharide

BACKGROUND AND OBJECTIVE

Lipopolysaccharide from gram-negative bacteria is one of the microbial-associated molecular patterns that initiate the immune/inflammatory response, leading to the tissue destruction observed in periodontitis. The aim of this study was to evaluate the role of the p38 mitogen-activated protein kinase (MAPK) signaling pathway in lipopolysaccharide-induced receptor activator of nuclear factor-kappaB ligand (RANKL) expression by murine periodontal ligament cells.

MATERIAL AND METHODS

Expression of RANKL and osteoprotegerin mRNA was studied by reverse transcription-polymerase chain reaction upon stimulation with lipopolysaccharide from Escherichia coli and Aggregatibacter actinomycetemcomitans. The biochemical inhibitor SB203580 was used to evaluate the contribution of the p38 MAPK signaling pathway to lipopolysaccharide-induced RANKL and osteoprotegerin expression. Stable cell lines expressing dominant-negative forms of MAPK kinase (MKK)-3 and MKK6 were generated to confirm the role of the p38 MAPK pathway. An osteoclastogenesis assay using a coculture model of the murine monocytic cell line RAW 264.7 was used to determine if osteoclast differentiation induced by lipopolysaccharide-stimulated periodontal ligament was correlated with RANKL expression.

RESULTS

Inhibiting p38 MAPK prior to lipopolysaccharide stimulation resulted in a significant decrease of RANKL mRNA expression. Osteoprotegerin mRNA expression was not affected by lipopolysaccharide or p38 MAPK. Lipopolysaccharide-stimulated periodontal ligament cells increased osteoclast differentiation, an effect that was completely blocked by osteoprotegerin and significantly decreased by inhibition of MKK3 and MKK6, upstream activators of p38 MAPK. Conditioned medium from murine periodontal ligament cultures did not increase osteoclast differentiation, indicating that periodontal ligament cells produced membrane-bound RANKL.

CONCLUSION

Lipopolysaccharide resulted in a significant increase of RANKL in periodontal ligament cells. The p38 MAPK pathway is required for lipopolysaccharide-induced membrane-bound RANKL expression in these cells.

Hyper-reactive PMNs in FcγRIIa 131 H/H genotype periodontitis patients

BACKGROUND

Receptors for the Fc part of IgG (FcgammaRIIa) on polymorphonuclear leukocytes (PMN) mediate phagocytosis and cell activation. Previous results show that one of the genetic variants of the FcgammaRIIa, the 131 H/H, is associated with more periodontal breakdown than the R/R. This may be due to hyper-reactivity of the H/H-PMNs upon interaction with bacteria.

AIM

To study whether the FcgammaRIIa genotype modifies the PMN reactivity in periodontitis patients.

MATERIAL AND METHODS

A cohort of 98 periodontitis patients was genotyped. From these, 10 H/H and 10 R/R consented to participate. PMNs were incubated with immune serum-opsonized Actinobacillus actinomycetemcomitans (A.a.). Phagocytosis, degranulation (CD63 and CD66b expression), respiratory burst and elastase release were assessed.

RESULTS

Patients of the H/H genotype showed more bone loss than those with the H/R or R/R genotype (p=0.038). H/H-PMNs phagocytosed more opsonized A.a. than did R/R-PMNs (p=0.019). The H/H-PMNs also expressed more CD63 and CD66b than did the R/R-PMNs (p=0.004 and 0.002, respectively) and released more elastase (p=0.001).

CONCLUSIONS

The genotyping results confirm previous reports that more periodontal destruction occurs in the H/H genotype than in the H/R or R/R genotype. The functional studies indicate a hyper-reactivity of the H/H-PMN in response to bacteria, which may be one of several pathways leading to more periodontal breakdown.

[Distribution of five periodontal pathogens in subgingival plaque in chronic periodontitis]

OBJECTIVE

To investigate the distribution of H. actinomycetemcomitans, P. gingivalis, P. intermedia, T. forsythensis and T. denticola in the subgingival plaque in the patients with chronic periodontitis.

METHODS

27 patients with chronic periodontitis were included. Two of the deepest pockets of each patient were selected as the study sites. Semi-quantification of subgingival microorganism samples was analyzed by multiplex polymerase chain reaction and reverse hybridization assay.

RESULTS

P. gingivalis, P. intermedia, T. forsythensis and T. denticola were detected in a high proportion of examined sites(corresponding values were 98.15%, 92.59%, 100% and 98.15%), however, the proportion of H. actinomycetemcomitans was low (20.37%). The levels of P. gingivalis and T. forsythensis were higher than the other three microorganisms with statistical significance.

CONCLUSION

The simultaneous infection of P. gingivalis, T. forsythensis, P. intermedia and T. denticola is found in the patients with chronic periodontitis, in which the levels of P. gingivalis and T. forsythensis are higher than the other two microorganisms.

Effects of Lipopolysaccharide on Newly Established Rat Dental Pulp–derived Cell Line with Odontoblastic Properties

To clarify mechanisms of pulp wound healing and regeneration, it is important to establish continuous odontoblast-lineage cell lines. In this study, we established the proliferating pulp progenitor cell lines from dental papilla cells of rat incisor. These cell lines showed high levels of alkaline phosphatase (ALP) activity, expression of Runx2 and dentin sialophosphoprotein (DSPP), and extracellular formation of mineralized nodules. By using the cell line with high expression level of DSPP and the prominent mineral deposition, we examined whether bacterial lipopolysaccharide (LPS) had effects on its odontoblastic properties and found that ALP activity, expression of DSPP and Runx2, and the formation of mineralized nodules were suppressed in LPS dose-dependent manner. These results indicate that our established pulp progenitor cell line exhibits odontoblastic properties, which were suppressed by LPS, suggesting that gram-negative bacterial infection might downregulate the odontoblast function.

Stimulatory response of neutrophils from periodontitis patients with periodontal pathogens

OBJECTIVE

Neutrophils play a crucial role in the defense of invading bacteria by releasing biologically active molecules. The response of peripheral blood neutrophils was studied in periodontitis-affected patients and in healthy controls towards stimulation to Porphyromonas gingivalis (Pg) and Actinobacillus actinomycetemcomitans (Aa) extracts.

MATERIALS AND METHODS

Peripheral venous blood was drawn from 23 adult patients with moderate to advanced chronic periodontitis (probing depth >or=5 mm, attachment loss >or=3 mm), and 30 healthy volunteers. Neutrophil response followed by metalloproteinase-9 (MMP-9) and interleukin-8 (IL-8) secretion was assayed by zymography and enzyme-linked immunosorbent assay, respectively, on both whole blood and purified neutrophils. In addition to periodontal pathogen extracts, known stimulating agents were tested, such as Escherichia coli-lipopolysaccharide (LPS), phytohemagglutinin, and zymosan A.

RESULTS

Neutrophil response, expressed as a secretion ratio under stimulated and non-stimulated conditions, measured in whole blood, showed no differences between periodontitis and healthy controls. Instead, in purified neutrophils from patients, MMP-9 exhibited a significantly higher secretion ratio with LPS and Pg (1.5- to 2-fold), whereas IL-8 showed a larger increase in secretion ratio (3- to 7-fold) in the presence of Pg, Aa, LPS, and zymosan A.

CONCLUSION

Peripheral neutrophils of periodontitis-affected patients are more reactive as suggested by their significantly higher response toward periodontal pathogen extracts and other stimulating agents.

Gingival Epithelial Cell Expression of Macrophage Inflammatory Protein-1α Induced by Interleukin-1β and Lipopolysaccharide

BACKGROUND

Elevated levels of the macrophage inflammatory protein-1alpha (MIP-1alpha) are reported in inflammatory bone diseases including periodontitis. We evaluated the ability of interleukin-1beta (IL-1beta) and bacterial lipopolysaccharides (LPSs) to modulate MIP-1alpha expression in epithelial cells, fibroblasts, and polymorphonuclear leukocytes (PMNs). We also evaluated the effect of MIP-1alpha as an osteoclast activating factor.

METHODS

Human gingival epithelial cells and fibroblasts were obtained by primary cell culture. PMNs were isolated from healthy controls. Human MG63 osteosarcoma cells were used as osteoblastic cells. After incubation of each cell type with IL-1beta, Porphyromonas gingivalis LPS, and Actinobacillus actinomycetemcomitans LPS, MIP-1alpha mRNA and secreted protein levels were quantified by reverse transcription-polymerase chain reaction, enzyme-linked immunosorbent assay, and immunohistochemistry. The ability of recombinant MIP-1alpha to induce osteoclast formation was determined by tartrate resistant acid phosphatase assay.

RESULTS

MIP-1alpha expression in PMNs and gingival epithelial cells was induced by IL-1beta and LPS, but neither induced MIP-1alpha expression in gingival fibroblasts or osteoblastic cells. MIP-1alpha was highly expressed in the basal epithelial layer of inflamed gingiva but not in healthy gingiva. MIP-1alpha induced osteoclast formation at an optimal concentration of 0.05 to 2 ng/ml.

CONCLUSIONS

MIP-1alpha expression by gingival epithelial cells may be important in initiating inflammation by facilitating accumulation and activation of leukocytes. The ability of MIP-1alpha to facilitate formation of multinuclear bone cells indicates a possible role in periodontitis-associated bone destruction. These findings indicate MIP-1alpha may play an important role in early and later stages of inflammatory-related periodontitis.

Clinical and microbiological effects of a combined mechanic-antibiotic therapy in subjects with Actinobacillus actinomycetemcomitans-associated periodontitis

PURPOSE

To evaluate the clinical and microbiological effects of a combined mechanic-antibiotic periodontal therapy in subjects that were tested positive for subgingival Actinobacillus actinomycetemcomitans (A.a.).

METHODS

The postoperative follow-up ranged from 12-115 months (average 39.2 months). This follow-up study analyzed the data of 53 subjects (37 females) aged from 16-59 years, who underwent systemic periodontal therapy with adjunctive systemic antibiotics between 1992-2001 and had their last re-examination including microbiological analysis done in 2003. The antibiotic regime was either amoxicillin/metronidazole or ciprofloxacine/metronidazole. During this study, A.a. was detected with two gene probe tests (IAI PadoTest 4.5 and DMDx/PathoTek) and cultivation on TSBV agar plates. The clinical situation was characterized with the help of pocket probing depths and subsequent categorization into three different groups (< or = 4 mm, 5-6 mm and > or = 7 mm).

RESULTS

After therapy, A.a. was detected with IAI PadoTest 4.5 in a magnitude between 3.0 x 10(3) up to 2.06 x 10(5) counts per specimen in 9 out of 53 subjects. Only two subjects tested positive for A.a. with the DMDx/PathoTek-assays and the agar cultivation. The clinical situation improved significantly in all subjects after systemic periodontal therapy. The treatment results remained stable during the course of the postoperative follow-up. Concerning the clinical data, no differences were found between the subjects that were tested positive and negative for A.a in the postoperative period.

Inhibition of host extracellular matrix destructive enzyme production and activity by a high-molecular-weight cranberry fraction

BACKGROUND AND OBJECTIVE

Periodontal diseases are a group of inflammatory disorders that are initiated by specific gram-negative bacteria and lead to connective tissue destruction. Proteolytic enzymes, including matrix metalloproteinases (MMPs) and elastase, produced by resident and inflammatory cells in response to periodontopathogens and their products, play a major role in gingival tissue destruction. The aim of this study was to investigate the effect of a high-molecular-weight fraction prepared from cranberry juice concentrate on MMP-3, MMP-9 and elastase activities, as well as on MMP production by human cells stimulated with lipopolysaccharide of Actinobacillus actinomycetemcomitans.

MATERIAL AND METHODS

MMP-3 and MMP-9 production by gingival fibroblasts and macrophages treated with the cranberry fraction and then stimulated with lipopolysaccharide was measured by enzyme-linked immunosorbent assay. MMP-3, MMP-9 and elastase activities in the presence of the cranberry fraction were evaluated using colorimetric or fluorogenic substrates. The changes in expression and phosphorylation state of fibroblast intracellular signaling proteins induced by A. actinomycetemcomitans lipopolysaccharide and the cranberry fraction were characterized by antibody microarrays.

RESULTS

The lipopolysaccharide-induced MMP-3 and MMP-9 responses of fibroblasts and macrophages were inhibited in a dose-dependent manner by the cranberry fraction. This fraction was found to inhibit fibroblast intracellular signaling proteins, a phenomenon that may lead to a down-regulation of activating protein-1 activity. MMP-3, MMP-9 and elastase activities were also efficiently inhibited by the cranberry fraction, even when it was used at low concentrations.

CONCLUSION

These results suggest that cranberry compounds offer promising perspectives for the development of novel host-modulating strategies for an adjunctive treatment of periodontitis.

Actinobacillus actinomycetemcomitans isolated from a case of cutaneous botryomycosis

Cutaneous botryomycosis is an uncommon chronic suppurative bacterial skin infection that can mimic a fungal infection both clinically and histopathologically. Causative bacteria, most commonly Staphylococcus aureus, aggregate to form characteristic granules. We report the case of a 52-year-old black man who developed cutaneous botryomycosis of the hand following trauma. Routine bacterial cultures grew S aureus and Actinobacillus actinomycetemcomitans, a fastidious gram-negative bacillus known to cause periodontal disease, endocarditis, and actinomycosislike soft tissue infections. Despite culture-proven eradication of S aureus with long-term appropriate antibiotic therapy, the lesion, resolved only after fluoroquinolone treatment directed against A. actinomycetemcomitans, suggesting that A. actinomycetemcomitans was of etiologic significance.

[Distribution of Haemopuilus actinomycetemcomitans in chronic periodontitis patients and periodontally healthy subjects]

OBJECTIVE

To investigate the prevalence of H. actinomycetemcomitans in Chinese chronic periodontitis (CP) patients and periodontally healthy adults.

METHODS

116 chronic periodontitis patients and 111 periodontally healthy adults were included. In each CP patient, subgingival plaque samples were collected from two sites of different molars with the greatest probing depth (PD) and one periodontally healthy site (PD < or =3 mm). The samples of periodontally healthy adults were obtained from the mesio-buccal site of one first upper molar. Bacteria DNA were extracted for detection of H. actinomycetemcomitans by 16S rRNA PCR.

RESULTS

The prevalence for H. actinomycetemcomitans of diseased sites (33.62%) was significantly higher than that of healthy sites from CP patients (0.86%) and the periodontally sites (0.90%) (P < 0.01). No significant difference was observed between male and female CP patients (P > 0.05). A decreasing trend of H. actinomycetemcomitans was observed as the age increased. And the pocket depth and clinical attachment losswas associated with the occurrence of H. actinomycetemcomitans in a positive mode. And H. actinomycetemcomitans was more often detected in the bleeding sites on probing.

CONCLUSION

H. actinomycetemcomitans was more frequently detected in periodontitis sites than periodontally healthy sites. For CP patients, a higher prevalence was associated with the seriously involved sites than those moderate and mild implicated sites. H. actinomycetemcomitans is considered to be the one of the periopathogens involved in the etiology of chronic periodontitis.