Significance of detection of Porphyromonas gingivalis, Bacteroides forsythus and Treponema denticola in periodontal pockets

A continuous flow PCR array microfluidic chip applied for simultaneous amplification of target genes of periodontal pathogens

The concept of time to place conversion makes using a continuous flow polymerase chain reaction (CF-PCR) microfluidic chip an ideal way to reduce the time required for amplification of target genes; however, it also brings about low throughput amplicons. Although multiplex PCR can simultaneously amplify more than one target gene in the chip, it may easily induce false positives because of cross-reactions. To circumvent this problem, we herein fabricated a microfluidic system based on a CF-PCR array microfluidic chip. By dividing the chip into three parts, we successfully amplified target genes of Porphyromonas gingivalis (P.g), Tannerella forsythia (T.f) and Treponema denticola (T.d). The results demonstrated that the minimum amplification time required for P.g, T.d and T.f was 2'07'', 2'51'' and 5'32'', respectively. The target genes of P.g, T.d and T.f can be simultaneously amplified in less than 8'05''. Such a work may provide a clue to the development of a high throughput CF-PCR microfluidic system, which is crucial for point of care testing for simultaneous detection of various pathogens.

Comparison of Periodontal Bacteria of Edo and Modern Periods Using Novel Diagnostic Approach for Periodontitis With Micro-CT

Ancient dental calculus, formed from dental plaque, is a rich source of ancient DNA and can provide information regarding the food and oral microbiology at that time. Genomic analysis of dental calculus from Neanderthals has revealed the difference in bacterial composition of oral microbiome between Neanderthals and modern humans. There are few reports investigating whether the pathogenic bacteria of periodontitis, a polymicrobial disease induced in response to the accumulation of dental plaque, were different between ancient and modern humans. This study aimed to compare the bacterial composition of the oral microbiome in ancient and modern human samples and to investigate whether lifestyle differences depending on the era have altered the bacterial composition of the oral microbiome and the causative bacteria of periodontitis. Additionally, we introduce a novel diagnostic approach for periodontitis in ancient skeletons using micro-computed tomography. Ancient 16S rDNA sequences were obtained from 12 samples at the Unko-in site (18th-19th century) of the Edo era (1603–1867), a characteristic period in Japan when immigrants were not accepted. Furthermore, modern 16S rDNA data from 53 samples were obtained from a database to compare the modern and ancient microbiome. The microbial co-occurrence network was analyzed based on 16S rDNA read abundance. Eubacterium species, Mollicutes species, and Treponema socranskii were the core species in the Edo co-occurrence network. The co-occurrence relationship between Actinomyces oricola and Eggerthella lenta appeared to have played a key role in causing periodontitis in the Edo era. However, Porphyromonas gingivalis, Fusobacterium nucleatum subsp. vincentii, and Prevotella pleuritidis were the core and highly abundant species in the co-occurrence network of modern samples. These results suggest the possibility of differences in the pathogens causing periodontitis during different eras in history.

Loop-Mediated Isothermal Amplification (LAMP): The Better Sibling of PCR?

In 1998, when the PCR technique was already popular, a Japanese company called Eiken Chemical Co., Ltd. designed a method known as the loop-mediated isothermal amplification of DNA (LAMP). The method can produce up to 109 copies of the amplified DNA within less than an hour. It is also highly specific due to the use of two to three pairs of primers (internal, external, and loop), which recognise up to eight specific locations on the DNA or RNA targets. Furthermore, the Bst DNA polymerase most used in LAMP shows a high strand displacement activity, which eliminates the DNA denaturation stage. One of the most significant advantages of LAMP is that it can be conducted at a stable temperature, for instance, in a dry block heater or an incubator. The products of LAMP can be detected much faster than in standard techniques, sometimes only requiring analysis with the naked eye. The following overview highlights the usefulness of LAMP and its effectiveness in various fields; it also considers the superiority of LAMP over PCR and presents RT-LAMP as a rapid diagnostic tool for SARS-CoV-2.

Characterization of a novel potential peptide import system in Treponema denticola

Treponema denticola is a major etiologic agent of chronic periodontitis. On the outer sheath of T. denticola, several proteins, such as the major outer sheath protein and dentilisin were detected, and among them, a 95 kDa protein which has not yet been characterized. The aim of this study was to characterize the function of this 95 kDa protein containing gene cluster. A gene encoding this 95 kDa protein (TDE_1072) of T. denticola was inactivated by homologous recombination. We compared growth curves between the TDE_1072 mutant and wild-type strains as well as differences in gene expression by DNA microarray analysis. Differential expression of genes identified by microarray analysis was confirmed by quantitative reverse transcription-polymerase chain reaction. The proteins encoded by TDE_1072, TDE_1073, TDE_1074, TDE_1075, and TDE_1076 shared respective similarities to the substrate-binding domain (DppA) of an ABC-type dipeptide/oligopeptide/nickel transport system, and to the permease components (DppB and DppC) and ATPase components (DppD and DppF) of an ABC-type dipeptide/oligopeptide/nickel transport system. Inactivation of dppA attenuated the growth of T. denticola and dppA-dppF were co-transcribed. In contrast, expression of oppB-oppF was up-regulated in the mutant. Our findings indicate that TDE_1072 may be a potential periplasmic solute binding protein encoded by dppA that is involved in the organization of a peptide uptake system with dppB-dppF.

Periimplant bacteria associated with different transmucosal designs or smoking habits

PURPOSE

This study is to compare periimplant microbiota associated with implant transmucosal designs or smoking habits.

METHODS

Submucosal samples from healthy 52 implants were collected for analysis of bacteria associated with bone-level (n = 37) or tissue-level (n = 15) implants or smoking habits, using quantitative polymerase chain reaction. Profiles of periimplant bacteria of smokers (n = 5) were investigated using PhyloChip Array version G3 and compared with nonsmokers (n = 5).

RESULTS

The number of bone-level implants positive for at least 1 pathogen was higher than that of tissue level; however, differences in each bacterium were insignificant. The prevalence and abundance of Treponema denticola in smokers were significantly higher than that in nonsmokers (P < 0.05). Smokers and nonsmokers exhibited similar periimplant microbiota based on the PhyloChip Array, but they could be distinguished by limiting observations to only 18 operational taxonomic units. Streptococcus macedonicus within Firmicutes and Prevotella within Bacteroidetes were more abundant in smokers compared with nonsmokers.

CONCLUSION

Prevalence of putative pathogens with bone-level implants was higher than tissue-level implants in nonsmokers. Firmicutes and Bacteroidetes were significantly higher in smokers. Smoking therefore strongly influenced peri-implant bacterial composition of bone-level implant.

Microbiological basis for periodontal therapy

The search for the etiologic agents of periodontal diseases started in the Golden Era of medical bacteriology, when the etiologic agents of many bacterial infections were isolated and characterized. After the initial enthusiasm in establishing the infectious nature and the true agents of periodontal diseases, this concept was virtually ignored for the next four decades. Until the early 1970s treatment regimens based on the non-specific plaque hypothesis were directed towards a non-specific reduction in plaque amount. Later, the specific plaque hypothesis established the role of some microorganisms such as A. actinomycetemcomitans, P. gingivalis, T. forsythensis, T. denticola, P. intermedia and F. nucleatum in different forms of periodontal diseases. It was recently suggested that these suspected periodontal pathogens seem to not act alone and interactions between species, especially the balance between pathogenic and beneficial species affect both progression of disease and response of tissues to periodontal therapy. Nowadays it is well established that one of the goals of therapy is to control such periodontal pathogens. Among the most commonly used therapies to treat periodontal infections are scaling and root planing (SRP), supragingival plaque control and periodontal surgeries. Many studies confirmed the reduction of "red complex" species by SRP, and apically repositioned flap can lead to an additional beneficial effect in the subgingival microbiota by decreasing levels of "red" and "orange complexes" species. Furthermore, the level of plaque control maintained by the patients has been considered a crucial step in preventing recurrence of destructive periodontitis.

Inhibitory effect of Lactobacillus reuteri on periodontopathic and cariogenic bacteria

The interaction between Lactobacillus reuteri, a probiotic bacterium, and oral pathogenic bacteria have not been studied adequately. This study examined the effects of L. reuteri on the proliferation of periodontopathic bacteria including Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum, Porphyromonas gingivalis, and Tannerella forsythia, and on the formation of Streptococcus mutans biofilms. Human-derived L. reuteri strains (KCTC 3594 and KCTC 3678) and rat-derived L. reuteri KCTC 3679 were used. All strains exhibited significant inhibitory effects on the growth of periodontopathic bacteria and the formation of S. mutans biofilms. These antibacterial activities of L. reuteri were attributed to the production of organic acids, hydrogen peroxide, and a bacteriocin-like compound. Reuterin, an antimicrobial factor, was produced only by L. reuteri KCTC 3594. In addition, L. reuteri inhibited the production of methyl mercaptan by F. nucleatum and P. gingivalis. Overall, these results suggest that L. reuteri may be useful as a probiotic agent for improving oral health.

Inhibition of host- and bacteria-derived proteinases by natural anthocyanins

BACKGROUND AND OBJECTIVES

Host- and bacteria-derived proteinases are considered to play critical roles in periodontitis progression. This study investigated the ability of a blackcurrant extract and its major anthocyanins (cyanidin-3-O-glucoside, cyanidin-3-O-rutinoside and delphinidin-3-O-rutinoside) to inhibit the activity of matrix metalloproteinases (MMPs), neutrophil elastase and periodontopathogen (Porphyromonas gingivalis, Tannerella forsythia and Treponema denticola) proteinases.

MATERIAL AND METHODS

Enzyme inhibition was detected using fluorometric and colorimetric assays after incubating blackcurrant extract and its major anthocyanins (at concentrations of 6.25, 12.5, 25 and 50 μg/mL) with MMPs, elastase or bacterial proteinases, along with their specific substrates. Substrate degradation was recorded every hour for up to 4 h.

RESULTS

The blackcurrant extract (50 μg/mL) inhibited all proteinases tested. MMP-1 and MMP-9 were significantly inhibited by pure anthocyanins at concentrations ranging from 6.25 to 50 μg/mL. Elastase activity was inhibited by cyanidin-3-O-glucoside and cyanidin-3-O-rutinoside in the range of 6.25-50 μg/mL and by delphinidin-3-O-rutinoside at 50 μg/mL. P. gingivalis, T. forsythia and T. denticola proteinases were also significantly inhibited by pure anthocyanins. In all cases, enzyme inhibition was time-dependent.

CONCLUSION

Our study showed that a blackcurrant extract and its major anthocyanins were able to inhibit the activity of host- and bacteria-derived proteinases. This suggests that such natural compounds may represent promising agents for use in adjunctive treatments for periodontitis.

Synergistic effects of lipopolysaccharides from periodontopathic bacteria on pro-inflammatory cytokine production in an ex vivo whole blood model

Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia have been strongly associated with chronic periodontitis. This disease is characterized by an accumulation of inflammatory cells in periodontal tissue and subgingival sites. The secretion of high levels of inflammatory cytokines by those cells is believed to contribute to periodontal tissue destruction. The aim of this study was to investigate the inflammatory response of whole blood from periodontitis patients following challenges with whole cells of P. gingivalis, T. denticola, and T. forsythia or their lipopolysaccharides (LPS), individually and in combination. Whole blood collected from seven periodontitis patients was stimulated with whole cells or LPS and the production of interleukin (IL)-1beta, IL-6, IL-8, and tumor necrosis factor alpha (TNF-alpha) were quantified by enzyme-linked immunosorbent assays. The mono and mixed challenges with whole bacterial cells or LPS induced the secretion of high amounts of IL-1beta, IL-6, IL-8, and TNF-alpha by the mixed leukocyte population from periodontitis patients. In addition, P. gingivalis LPS, T. denticola LPS, and T. forsythia LPS acted in synergy to induce high levels of IL-1beta and TNF-alpha. This study suggests that P. gingivalis, T. denticola, and T. forsythia may contribute to the immunodestructive host response characteristic of periodontitis through synergistic effects of their LPS on the inflammatory response induced by a mixed population of leukocytes.

Biofilms and bacterial imbalances in chronic wounds: anti-Koch

Microbial imbalances and synergistic relationships between bacteria in medically important biofilms are poorly researched. Consequently, little is known about how synergy between bacteria may increase the net pathogenic effect of a biofilm in many diseases and infections, including chronic wounds. Microbial synergy in chronic wounds may increase virulence and pathogenicity, leading to enhanced tissue degradation, malodour and in some cases, an impairment of the host immune response. Microbial synergy and growth within a biofilm provide a competitive advantage to the microorganisms cohabiting in a wound, thereby promoting their survival and tolerance and resistance to antimicrobial agents. The aim of this article was to provide greater insight into microbial imbalances found within wound biofilms and the significance they may have on non healing and infected wounds. We also present two possible hypotheses which could explain the role microorganisms play in non healing chronic wounds and offer possible strategies for combating harmful and detrimental biofilms.

Periodontic-Endodontic Interrelationship – A Review

Pulpal and periodontal problems are responsible for more than 50% of tooth mortality today. There is general agreement today that the vast majority of pulpal and periodontal lesions are a result of bacterial infection. Under which conditions and especially in which direction spread of the disease occurs in the pulpo-periodontal continuum remains a matter of controversy. Diagnosis is complicated by the fact that these diseases are too frequently viewed as independent entities when recognition of their interrelationship is critical to successful resolution & treatment of these lesions often requires combined periodontic & endodontic therapy

Porphyromonas gingivalis with either Tannerella forsythia or Treponema denticola induces synergistic IL-6 production by murine macrophage-like J774.1 cells

BACKGROUND

Chronic periodontitis is caused by mixed bacterial infection. Porphyromonas gingivalis, Tannerella forsythia and Treponema denticola are frequently detected in deep periodontal pockets. We demonstrate that these bacteria induce proinflammatory cytokine production by the mouse macrophage-like cell line J774.1.

MATERIALS AND METHODS

J774.1 cells were incubated with and without bacteria for 24h in 96-well flat-bottomed plates. The culture supernatants were analyzed by enzyme-linked immunosorbent assay for secreted mouse interleukin (IL)-6, monocyte chemoattractant protein-1, IL-23, IL-1 beta and tumor necrosis factor-alpha. The cytokine concentrations were determined using a standard curve prepared for each assay.

RESULTS

Mixed infection with P. gingivalis and either T. forsythia or T. denticola at 10(5)CFU/ml acted synergistically to increase IL-6 production, but not monocyte chemoattractant protein-1, IL-23, IL-1 beta or tumor necrosis factor-alpha production. Gingipain inhibitors KYT-1 and KYT-36 inhibited IL-6 production by J774.1 cells incubated with 10(5)CFU/ml of mixed bacteria.

CONCLUSION

These results suggest that P. gingivalis with either T. forsythia or T. denticola directly induces synergistic IL-6 protein production and that gingipains play a role in this synergistic effect.

Rapid detection of Actinobacillus actinomycetemcomitans using a loop-mediated isothermal amplification method

INTRODUCTION

Actinobacillus actinomycetemcomitans has been implicated in the etiology of aggressive periodontitis. In this study, we applied a novel nucleic acid amplification method, called loop-mediated isothermal amplification (LAMP), which amplifies DNA with high specificity, efficiency and rapidity under isothermal conditions, allowing the rapid detection of A. actinomycetemcomitans.

METHODS

We designed the primers for detecting A. actinomycetemcomitans and evaluated the specificity and sensitivity of the assay.

RESULTS

The LAMP primers used in this study successfully amplified serotypes a-e of A. actinomycetemcomitans, while other oral bacteria were not amplified. By measuring the precipitation of magnesium pyrophosphate, we could quantify the chromosomal DNA of A. actinomycetemcomitans. The detection limits using the real-time turbidimetry analysis were 5.8 x 10(2)-5.8 x 10(7) copies of A. actinomycetemcomitans template DNA per reaction tube. In addition, the LAMP assay was used for the rapid detection of A. actinomycetemcomitans in clinical specimens from eight individuals. The results with the LAMP method were similar to those using conventional polymerase chain reaction.

CONCLUSION

Our results suggest that the LAMP-based assay is very useful for the rapid detection of A. actinomycetemcomitans.

Effect of Porphyromonas gingivalis PrtC on cytokine expression in ECV304 endothelial cells and its level in subgingival plaques from patients with chronic periodontitis

AIM

To investigate the effect of the collagenase gene (prtC) product of Porphyromonas gingivalis on inducing host cells to secrete inflammatory cytokines, and to discuss the correlation between the PrtC level in subgingival plaque samples and clinical parameters.

METHODS

A prokaryotic expression system pET32a-prtC-Escheria coli BL21DE3 was constructed. Antigenicity and immunoreactivity of the recombinant PrtC protein (rPrtC) was identified by Western blotting. ELISA was applied to detect interleukin (IL)-1alpha, IL-8, and TNF-alpha levels in supernatants from rPrtC-induced human umbilical vein endothelial cells (HUVEC) originated ECV304 cells. Clinical parameters recorded at baseline and after treatment included bleeding on probing (BOP), probing depth (PD), and attachment loss (AL). ELISA was established to measure the PrtC level in 196 subgingival plaque samples from 49 patients with chronic periodontitis.

RESULTS

After coincubation with 1 microg/mL rPrtC for 24 h and with 5 or 10 microg/mL rPrtC for 12 h, the levels of IL-1 alpha, IL-8, and TNF-alpha secreted by the ECV304 cells increased significantly (P<0.05). The PrtC level in the BOP-positive or the > or =5 mm AL or > or = 6 mm PD sites was higher than that in the BOP-negative or the < or =2 mm AL or < or =6 mm PD sites (P<0.05), respectively. Compared with baseline, the PrtC levels in different AL sites or in the < or =6 mm PD pockets decreased remarkably after treatment (P<0.01), but in the BOP-positive or in the > 6 mm PD sites, the PrtC levels changed insignificantly (P>0.05).

CONCLUSION

rPrtC is able to directly induce host cells to synthesize and secrete IL-1 alpha, IL-8, and TNF-alpha. The PrtC level in subgingival samples is correlated with BOP, AL, and PD.

Potentiel pathogénique de Porphyromonas gingivalis, Treponema denticola et Tannerella forsythia, le complexe bactérien rouge associé à la parodontite

Periodontitis are mixed bacterial infections leading to destruction of tooth-supporting tissues, including periodontal ligament and alveolar bone. Among over 500 bacterial species living in the oral cavity, a bacterial complex named "red complex" and made of Porphyromonas gingivalis, Treponema denticola and Tannerella forsythia has been strongly related to advanced periodontal lesions. While periodontopathogenic bacteria are the primary etiologic factor of periodontitis, tissue destruction essentially results from the host immune response to the bacterial challenge. Members of the red complex are Gram negative anaerobic bacteria expressing numerous virulence factors allowing bacteria to colonize the subgingival sites, to disturb the host defense system, to invade and destroy periodontal tissue as well as to promote the immunodestructive host response. This article reviews current knowledge of the pathogenic mechanisms of bacteria of the red complex leading to tissue and alveolar bone destruction observed during periodontitis.

Inhibition of periodontopathogen-derived proteolytic enzymes by a high-molecular-weight fraction isolated from cranberry

BACKGROUND

Porphyromonas gingivalis, Tannerella forsythia and Treponema denticola are three major aetiological agents of chronic periodontitis. The strong proteolytic activities of these bacteria are critical to their survival since their energy source is obtained from peptides and amino acids derived from proteins. In addition, proteases are important factors contributing to periodontal tissue destruction by a variety of mechanisms, including direct tissue degradation and modulation of host inflammatory responses.

OBJECTIVES

The aim of this study was to investigate the effect of non-dialysable material (NDM) prepared from cranberry juice concentrate on the proteolytic activities of P. gingivalis, T. forsythia and T. denticola.

METHODS

The effect of NDM on gingipain and dipeptidyl peptidase IV (DPP IV) activities of P. gingivalis, trypsin-like activity of T. forsythia and chymotrypsin-like activity of T. denticola was evaluated using synthetic chromogenic peptides. In addition, the capacity of P. gingivalis to degrade fluorescein-labelled type I collagen and fluorescein-labelled transferrin in the presence of NDM was evaluated by fluorometry.

RESULTS

NDM dose-dependently inhibited the proteinases of P. gingivalis, T. forsythia and T. denticola as well as type I collagen and transferrin degradation by P. gingivalis.

CONCLUSIONS

These results suggest that NDM has the potential to reduce either the proliferation of P. gingivalis, T. forsythia and T. denticola in periodontal pockets or their proteinase-mediated destructive process occurring in periodontitis.

Inflammatory responses of a macrophage/epithelial cell co-culture model to mono and mixed infections with Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia

Accumulated evidence points to Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia as three major etiologic agents of chronic periodontitis. Epithelial cells and macrophages play a major role in the host response to periodontopathogens, and the secretion of inflammatory mediators and matrix metalloproteinases (MMPs) by these host cells is believed to contribute to periodontal tissue destruction. The aim of this study was to investigate the inflammatory response of a macrophage/epithelial cell co-culture model following mono or mixed infections with the above three periodontopathogens. An in vitro co-culture model composed of epithelial-like transformed cells (HeLa cell line) and macrophage-like cells (phorbol myristic acid-differentiated U937 monocytic cell line) was challenged with whole cells or lipopolysaccharides (LPS) of P. gingivalis, T. denticola, and T. forsythia, individually and in combination. Following stimulation, the production of interleukin-1 beta (IL-1beta), IL-6, IL-8, tumor necrosis factor alpha (TNF-alpha), regulated on activation normal T cell expressed and secreted (RANTES), prostaglandin E2 (PGE2), and MMP-9 were quantified by enzyme-linked immunoassays. We observed that mono or mixed infections of the co-culture model induced the secretion of IL-1beta, IL-6, IL-8, PGE2, and MMP-9. P. gingivalis and T. forsythia induced an increase in RANTES secretion, whereas T. denticola alone or in combination resulted in a significant decrease in RANTES levels. All LPS challenges induced an increase in chemokine, MMP-9, and PGE2 production. No synergistic effect on the production of cytokines, chemokines, PGE2, and MMP-9 was observed for any of the bacterial or LPS mixtures tested. This study supports the view that P. gingivalis, T. denticola, and T. forsythia may induce high levels of pro-inflammatory mediators and MMP-9 in periodontal lesions, thus contributing to the progression of periodontitis.

Synergistic biofilm formation byTreponema denticolaandPorphyromonas gingivalis

Biofilm formation is an important step in the etiology of periodontal diseases. In this study, in vitro biofilm formation by Treponema denticola and Porphyromonas gingivalis 381 displayed synergistic effects. Confocal microscopy demonstrated that P. gingivalis attaches to the substratum first as a primary colonizer followed by coaggregation with T. denticola to form a mixed biofilm. The T. denticola flagella mutant as well as the cytoplasmic filament mutant were shown to be essential for biofilm formation as well as coaggregation with P. gingivalis. The major fimbriae and Arg-gingipain B of P. gingivalis also play important roles in biofilm formation with T. denticola.

Detection of periodontopathic bacteria and an oxidative stress marker in saliva from periodontitis patients

We assessed the salivary levels of periodontopathic bacteria and 8-hydroxydeoxyguanosine (8-OHdG) in patients with periodontitis. The salivary levels of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Tannerella forsythia (formerly Bacteroides forsythus) were assessed using real-time polymerase chain reaction. The 8-OHdG levels were determined using an enzyme-linked immunosorbent assay. The salivary levels of 8-OHdG, P. gingivalis, and T. forsythia in the periodontitis patients were significantly higher than those in healthy subjects. By contrast, the A. actinomycetemcomitans level in healthy subjects was higher than that in periodontitis patients. 8-OHdG was significantly correlated with P. gingivalis. Statistically significant decreases in the levels of P. gingivalis, probing depth, bleeding on probing, and 8-OHdG were observed after initial periodontal treatment. These results suggest that the 8-OHdG levels in saliva reflect the load of periodontal pathogens. 8-OHdG could be a useful biomarker for assessing periodontal status accurately, and for evaluating the efficacy of periodontal treatment.

Loop-mediated isothermal amplification method for rapid detection of the periodontopathic bacteria Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola

Loop-mediated isothermal amplification (LAMP), a novel nucleic acid amplification method, was developed for the rapid detection of the major periodontal pathogens Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola. The LAMP method amplifies DNA with high specificity, efficiency, and rapidity under isothermal conditions using a set of four specially designed primers and a DNA polymerase with strand displacement activity. In this study, we initially designed the primers for LAMP assays to detect these bacteria and evaluated the specificity and sensitivity of these assays. The specificities of the primers for these bacteria were examined using various oral bacteria and various reaction times. The lower detection limits of the 60-min LAMP reaction without loop primers were 1 microg/tube for P. gingivalis, 10 fg/tube for T. forsythia, and 1 ng/tube for T. denticola. Addition of the loop primers for each bacterium improved the detection specificities and sensitivities by several magnitudes. Furthermore, LAMP assays were applied to the rapid detection of these periodontal pathogens in clinical specimens, and the results were compared with those of conventional PCR detection. The results of the LAMP assays corresponded to those of conventional PCR assays. These results indicate that the LAMP assay is an extremely rapid, highly sensitive, specific method. This method is very useful for the rapid detection of periodontopathic bacteria and the diagnosis of periodontal disease.

Microbiological diagnostic testing in the treatment of periodontal diseases

A variety of microbiological diagnostic tests are available for clinicians to use for evaluation of patients with periodontal disease. Each one has its own unique set of advantages and disadvantages, and probably the most useful information for the clinician can be obtained using a combination of the various analytic methods. The tests appear to have their greatest utility when used on patients with chronic or aggressive periodontitis who do not respond favorable to conventional mechanical therapy. The major limitation of all microbiological tests is that the information obtained is relevant to the site sampled, and may not be representative of the microflora of the entire dentition. However, since it is often only specific sites that do not respond to initial therapy, knowing the constituents of the microflora that populate these sites is clinically relevant.

ANTI-PHAGOCYTIC ROLE OF SURFACE FIBROUS STRUCTURE OF AN INVASIVE PORPHYROMONAS GINGIVALIS STRAIN

Recent studies have shown that invasive and non-invasive strains of Porphyromonas gingivalis can both be isolated from patients with periodontitis. We examined the interaction between an invasive 16-1 P. gingivalis strain and phagocytes obtained from human peripheral blood and guinea pig peritoneal cavity. Phagocytes from human peripheral blood, mainly polymorphonuclear leukocytes (PMNs) isolated by centrifugation in Ficoll Hypaque, and macrophages collected from the peritoneal cavity of guinea pigs, were exposed to P. gingivalis cells. After this exposure, greater numbers of the non-invasive P. gingivalis ATCC 33277 were observed in human PMNs and guinea pig macrophages compared with the invasive P. gingivalis 16-1. Electron microscopic observations showed that invasive 16-1 within phagosomes in human PMNs and guinea pig macrophages retained their surface fibrous structures as well as their outer membranes. Electron microscopic examination showed that destruction and damage to the cell membranes and inner structures were clear in human PMNs and guinea pig macrophages after exposure to invasive 16-1 for 6 and 24 hours; this was a clear difference from exposure to the non-invasive ATCC 33277. Release of lactate dehydrogenase (LDH) activities into the culture supernatant of PMNs after exposure to the invasive 16-1 for 4 and 6 hours was significantly greater than that after exposure to the non-invasive ATCC 33277 (p<0.05). On the other hand, the LDH activity after exposure for 21 hours to the invasive 16-1 was significantly lower than that of untreated cells and cells after exposure to the non-invasive ATCC 33277 strain (p<0.05). The PMN viabilities after exposure to cells of the invasive 16-1 for 3, 4, and 6 hours as evaluated by trypan blue staining were similar to those after exposure to cells of the non-invasive ATCC 33277, but that after exposure to the invasive 16-1 strain for 21 hours was significantly lower than that after exposure to cells of the non-invasive ATCC 33277 strain.

EFFECTS OF A MIXED INFECTION WITH Porphyromonas gingivalis AND Treponema denticola ON ABSCESS FORMATION AND IMMUNE RESPONSES IN MICE

Porphyromonas gingivalis and Treponema denticola have been found together in lesions of human periodontitis. We examined the ability of a mixed infection by both bacteria to synergistically form abscesses and disturb immune responses in mice. Absorbance of an invasive P. gingivalis 16-1 strain grown in tryptic soy broth and T. denticola ATCC 33520 strain grown in TYGVS medium were adjusted. BALB/c mice were injected with 200 microliters of the cell suspension at a site on the lateral dorsal area. The sizes of the subsequent subcutaneous abscesses were measured with a caliper gauge, and the area was expressed in square mm. Mixed infections by P. gingivalis and T.denticola produced larger abscesses than those formed after mono-infections by either P. gingivalis or T.denticola. The abscesses caused by mixed infection reached their maxima on the 6th day and maintained that size for the subsequent 5 days. The delayed type hypersensitivities against extracted antigens of P.gingivalis in mixed infection mice were significantly lower than those in the mono-infected mice. However, the IgG response to sonicated antigen of P.gingivalis did not differ between the two groups. The sizes of the abscesses caused by mixed infections in mice immunized with whole cells of P.gingivalis 16-1 were compared to those caused in sham-immunized mice. The average size of the abscess caused by mixed infection in immunized mice did not differ from that in sham-immunized mice, but many of the abscesses in immunized mice ruptured on the 4th or 5th day, followed by recovery in two weeks. These results suggest that mixed infection with P.gingivalis and T.denticola attenuates protective immune responses.

Role for recombinant gamma-glutamyltransferase from Treponema denticola in glutathione metabolism

Volatile sulfur compounds, including hydrogen sulfide (H(2)S), have been implicated in the development of periodontal disease. Glutathione is an important thiol source for H(2)S production in periodontal pockets. Our recent studies have delineated a pathway of glutathione metabolism in Treponema denticola that releases H(2)S. In this pathway, gamma-glutamyltransferase (GGT) has been proposed to catalyze the first step of glutathione degradation. We have cloned the gene of GGT from T. denticola, which contains an open reading frame of 726 bp encoding a protein of 241 amino acids. Transformation of this gene into Escherichia coli led to the expression of a recombinant protein. After purification by chromatography, the recombinant protein showed enzymatic activity typical of GGT, catalyzing the degradation of Na-gamma-glutamyl-4-nitroaniline (GNA) and the hydrolysis of glutathione, releasing glutamic acid or glutamine and cysteinylglycine. L-Cysteine is not a substrate of GGT. Importantly, GNA, when added to T. denticola, was able to compete with glutathione and inhibit the production of H(2)S, ammonia, and pyruvate. This was accompanied by the suppression of hemoxidative and hemolytic activities of the bacteria. Purified GGT was inactivated by TLCK (Nalpha-p-tosyl-L-lysine chloromethyl ketone) and proteinase K treatment. However, higher enzymatic activity was demonstrated in the presence of 2-mercaptoethanol and dithiothreitol. Our further experiments showed that the addition of recombinant GGT to Porphyromonas gingivalis, a bacterium without significant glutathione-metabolizing capacity, drastically increased the utilization of glutathione by the bacterium, producing H(2)S, ammonia, and pyruvate. This was again accompanied by enhanced bacterial hemoxidative and hemolytic activities. Together, the results suggest an important role for GGT in glutathione metabolism in oral bacteria.