Presence of Porphyromonas gingivalis in gingival squamous cell carcinoma

Periodontal disease has been recently linked to a variety of systemic conditions such as diabetes, cardiovascular disease, preterm delivery, and oral cancer. The most common bacteria associated with periodontal disease, Porphyromonas gingivalis （P. gingivalis） has not yet been studied in the malignant gingival tissues. The objective of this study was to investigate the presence of R gingivalis in specimens from squamous cell carcinoma patients. We have performed immunohistochemical staining to investigate the presence of R gingivafis and Streptococcus gordonii （S. gordonii）, a non invasive oral bacteria, in paraffin embedded samples of gingival squamous cell carcinoma （n=10） and normal gingiva （n=5）. Staining for R gingivalis revealed the presence of the bacteria in normal gingival tissues and gingival carcinoma, with higher levels （more than 33%, P〈0.05） detected in the carcinoma samples. The staining intensity was also significantly enhanced in the malignant tissue by 2 folds （P〈0.023） compared to specimens stained for the non-invasive S. gordonii. R gingivalis is abundantly present in malignant oral epithelium suggesting a potential association of the bacteria with gingival squamous cell carcinoma.

Association between infection of different strains of Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans in subgingival plaque and clinical parameters in chronic periodontitis

Objective： The aim of this study was to investigate subgingival infection frequencies ofPorphyromonas gingivalis and Actinobacillus actinomycetemcomitans strains with genetic variation in Chinese chronic periodontitis （CP） patients and to evaluate its correlation with clinical parameters. Methods： Two multiplex polymerase chain reaction （PCR） assays were developed to detect the 16SrDNA, collagenase （prtC） and fimbria （fimA） genes of P. gingivalis and the 16SrDNA, leukotoxin （lktA） and fimbria-associated protein （fap） genes ofA. actinomycetemcomitans in 60 sulcus samples from 30 periodontal healthy subjects and in 122 subgingival plaque samples from 61 patients with CP. The PCR products were further T-A cloned and sent for nucleotide sequence analysis. Results： The 16SrDNA,prtC andfimA genes ofP. gingivalis were detected in 92.6%, 85.2% and 80.3% of the subgingival plaque samples respectively, while the 16SrDNA, lktA andfap genes ofA. actinomycetemcomitans were in 84.4%, 75.4% and 50.0% respectively. Nucleotide sequence analysis showed 98.62%-100% homology of the PCR products in these genes with the reported sequences. P. gingivalis strains with prtC＋/fimA＋ and A. actinomycetemcomitans with lktA＋ were predominant in deep pockets （〉6 mm） or in sites with attachment loss 〉5 mm than in shallow pockets （3-4 mm） or in sites with attachment loss 〈2 mm （P〈0.05）. P. gingivalis strains withprtC＋/fimA＋ also showed higher frequency in gingival index （GI）=3 than in GI=1 group （P〈0.05）. Conclusion： Infection ofP. gingivalis with prtC＋/fimA＋ and A. actinomycetemcomitans with lktA＋ correlates with periodontal destruction of CP in Chinese. Nonetheless P. gingivalis fim4, prtC genes and A. actinomycetem- comitans lktA gene are closely associated with periodontal destruction, while A. actinomycetemcomitansfap gene is not.

Analysis of differential expression of tight junction proteins in cultured oral epithelial cells altered by Porphyromonas gingivalis,Porphyromonas gingivalis lipopolysaccharide,and extracellular adenosine triphosphate

Tight junctions （TJs） are the most apical intercellular junctions of epithelial cells formed by occludin, claudins, junctional adhesion molecules （JAMs）, and zonula occludens （ZO）. Tight junction proteins can sense the presence of bacteria and regulate the transcription of target genes that encode effectors and regulators of the immune response. The aim of this study was to determine the impact of TJ proteins in response to Porphyromonas gingivalis （P. gingivalis）, P. gingivalis lipopolysaccharide （P. gingivalis LPS）, and extracellular adenosine triphosphate （ATP） in the oral epithelial cell culture model. Quantified real time- polymerase chain reaction （RT-PCR）, immunoblots, and immunostaining were performed to assess the gene and protein expression in TJs. It was found that P. gingivalis infection led to transient upregulation of the genes encoding occludin, claudin- 1, and claudin-4 but not JAM-A, claudin-15, or ZO-1, while P. gingivalis LPS increased claudin-1, claudin-15, and ZO-1 and decreased occludin, JAM-A, and claudin-4. Tight junction proteins showed significant upregulation in the above two groups when cells were pretreated with ATP for 3 h. The findings indicated that P. gingivalis induced the host defence responses at an early stage. P. gingivalis LPS exerted a more powerful stimulatory effect on the disruption of the epithelial barrier than P. gingivalis. ATP stimulation enhanced the reaction of TJ proteins to P. gingivalis invasion and LPS destruction of the epithelium.

Micromolar sodium fluoride mediates anti-osteoclastogenesis in Porphyromonas gingivalis-induced alveolar bone loss

Osteoclasts are bone-specific multinucleated cells generated by the differentiation of monocyte/macrophage lineage precursors. Regulation of osteoclast differentiation is considered an effective therapeutic approach to the treatment of bone-lytic diseases. Periodontitis is an inflammatory disease characterized by extensive bone resorption. In this study, we investigated the effects of sodium fluoride （NaF） on osteoclastogenesis induced by Porphyromonas gingivalis, an important colonizer of the oral cavity that has been implicated in periodontitis. NaF strongly inhibited the P. gingivalis-induced alveolar bone loss. That effect was accompanied by decreased levels of cathepsin K, interleukin （IL）-1β, matrix metalloproteinase 9 （MMP9）, and tartrate-resistant acid phosphatase, which were up-regulated during P. gingivalis-induced osteoclastogenesis. Consistent with the in vivo anti-osteoclastogenic effect, NaF inhibited osteoclast formation caused by the differentiation factor RANKL （receptor activator of nuclear factor KB ligand） and macrophage colony-stimulating factor （M-CSF）. The RANKL-stimulated induction of the transcription factor nuclear factor of activated T cells （NFAT） cl was also abrogated by NaF. Taken together, our data demonstrate that NaF inhibits RANKL-induced osteoclastogenesis by reducing the induction of NFATcl, ultimately leading to the suppressed expression of cathepsin K and MMP9. The in vivo effect of NaF on the inhibition of P. gingivalis-induced osteoclastogenesis strengthens the potential usefulness of NaF for treating periodontal diseases.

Characterization of Fusobacterium nucleatum ATCC 23726 adhesins involved in strain-specific attachment to Porphyromonas gingivalis

Bacterial adherence is an essential virulence factor in pathogenesis and infection. Fusobacterium nucleatum has a central role in oral biofilm architecture by acting as a bridge between early Gram-positive and late Gram-negative colonizers that do not otherwise adhere to each other. In this study, we survey a key adherence interaction of F. nucleatum with Porphyromonas gingivalis, and present evidence that multiple fusobacterial adhesins have a role in the attachment of F. nucleatum ATCC 23726 to P. gingivalis in a highly strain-dependent manner. Interaction between these species displayed varying sensitivities to arginine, galactose and lactose. Arginine was found to hamper coaggregation by at least 62% and up to 89% with several P. gingivalis strains and galactose inhibition ranged from no inhibition up to 58% with the same P. gingivalis strains. Lactose consistently inhibited F. nucleatum interaction with these P. gingivalis strains ranging from 40% to 56% decrease in coaggregation. Among the adhesins involved are the previously described Fap2 and surprisingly, RadD, which was described in an earlier study for its function in attachment of F. nucleatum to Gram-positive species. We also provide evidence for the presence of at least one additional adhesin that is sensitive to arginine but unlike Fap2 and RadD, is not a member of the autotransporter family type of fusobacterial large outer membrane proteins. The strain-specific binding profile of multiple fusobacterial adhesins to P. gingivalis highlights the heterogeneity and complexity of interspecies interactions in the oral cavity.

Role of α-Tubulin Acetylation and Protein Kinase D2 Ser/Tyr Phosphorylation in Modulation by Ghrelin of Porphyromonas gingivalis-Induced Enhancement in Matrix Metalloproteinase-9 (MMP-9) Secretion by Salivary Gland Cells

Matrix metalloproteinas-9 (MMP-9) is a glycosylated endopeptidase, and hence its processing between the endoplasmic reticulum (ER), Golgi and trans-Golgi (TGN) network remains under a strict control of factors that affect the microtubule (MT) stabilization, and the recruitment and activation of coat and cargo proteins, including ADP-ribosylation factors (Arfs) and protein kinase D (PKD). Here, we report on the factors implicated in the regulation of MMP-9 secretion by salivary gland acinar cells in response to P. gingivalis LPS, and the effect of hormone, ghrelin. We show that the LPS-elicited induction in MMP-9 secretion is associated with the increase in α-tubulin acetylation and the enhancement in MT stabilization, while the modulatory effect of ghrelin is reflected in a decrease in α-tubulin acetylation. Further, the effect of the LPS occurs in concert with up-regulation in Arf-guanine nucleotide exchange factor (GEF)-mediated Arf1 activation and the TGN recruitment of PKD2, while ghrelin exerts the modulatory effect on Arf-GEF activation. Moreover, we reveal that the LPS-induced up-regulation in MMP-9 secretion is reflected in a marked increase in PKCδ-mediated PKD2 phosphorylation on Ser, while the modulatory effect of ghrelin is manifested by the SFK-PTKs-dependent phosphorylation of PKD2 on Tyr. The findings demonstrate that MT stabilization along with Arf-GEF-mediated Arf1/PKD2 activation play a major role in P. gingivalis LPS-induced up-regulation in salivary gland acinar cell MMP-9 secretion, and point the modulatory mode of action by ghrelin.

Intragingival injection of Porphyromonas gingivalis-derived lipopolysaccharide induces a transient increase in gingival tumour necrosis factor-a, but not interleukin-6,in anaesthetised rats

This study used in vivo microdialysis to examine the effects of intragingival application of lipopolysaccharide（LPS） derived from Porphyromonas gingivalis（Pg-LPS） on gingival tumour necrosis factor（TNF）-a and interleukin（IL）-6 levels in rats. A microdialysis probe with an injection needle attached to the surface of the dialysis membrane was implanted into the gingiva of the upper incisor. For comparison, the effects of LPS derived from Escherichia coli（Ec-LPS） on IL-6 and TNF-a levels were also analysed. Pg-LPS（1 mg/1 m L） or Ec-LPS（1 or 6 mg/1 m L） was applied by microsyringe, with gingival dialysates collected every hour. Enzyme-linked immunosorbent assay（ELISA） revealed that gingival dialysates contained approximately 389 pg？m L21 of IL-6 basally; basal TNF-a levels were lower than the detection limit of the ELISA. Pg-LPS failed to alter IL-6 levels but markedly increased TNF-a levels, which remained elevated for 2 h after treatment. Neither IL-6 nor TNF-a were affected by Ec-LPS. Reverse transcriptase-polymerase chain reaction（RT-PCR） analysis revealed that the gingiva expresses Toll-like receptor（TLR） 2 and TLR4 m RNA. Immunohistochemical examination showed that TLR2 and TLR4 are expressed by gingival epithelial cells. The present study provides in vivo evidence that locally applied Pg-LPS, but not Ec-LPS, into the gingiva transiently increases gingival TNF-a without affecting IL-6. The present results suggest that TLR2 but not TLR4 expressed on gingival epithelial cells may mediate the Pg-LPS-induced increase in gingival TNF-a in rats.

An early report: a modified porphyrin-linked metronidazole targeting intracellular Porphyromonas gingivalis in cultured oral epithelial cells

Porphyromonas gingivalis （P. gingivalis） has a strong association with the pathogenesis of periodontal disease. Recurrence of periodontal disease following therapy is attributed to numerous factors, and of growing interest is the potential problem of intracellular bacteria that are able to persist and multiply within the host cell, thereby facilitating relapse of infection. The effect of antibiotic therapy in controlling P. gingivalis is questionable. Accordingly, while metronidazole is very effective against anaerobic extracellular P. gingivalis by disrupting the DNA of anaerobic microbial cells, this antibiotic does not effectively penetrate into mammalian cells to inhibit intracellular bacteria. Therefore in the present study, a modified porphyrin-linked metronidazole adducts, developed in our laboratory, was used to kill intracellular P. gingivalis. A series of experiments were performed, including cytotoxicity assays and cellular uptake of adducts by flow cytometry coupled with live cell imaging analysis, P. gingivalis invasion and elimination assays, and the analysis of colocalization of P. gingivalis and porphyrin-linked metronidazole by confocal laser scanning microscopy. Findings indicated that P. gingivalis and porphyrin-linked metronidazole were colocalized in the cytoplasm, and this compound was able to kill P. gingivalis intracellular with a sufficient culture time. This is a novel antimicrobial approach in the elimination of P. gingivalis from the oral cavity.

BET protein inhibitor apabetalone represses Porphyromonas gingivalis LPS-induced macrophage M1 polarization via regulating miR-130a/STAT3 axis

Periodontitis is a frequent chronic inflammatory disorder destroying periodontium.Recent studies have revealed the role of bromodomain and extraterminal domain inhibitor(BETi)and microRNA(miR)-130a in regulating macrophage polarization and pro-inflammatory response.However,little is known about whether apabetalone(a novel BETi)and miR-130a are correlated with chronic inflammatory state in periodontitis by regulating macrophage polarization.Here murine RAW264.7 macrophages were applied as an in vitro inflammatory model.After treatment with Porphyromonas gingivalis-derived lipopolysaccharide(Pg LPS)and apabetalone,the expression of macrophage M1 polarization markers and inflammatory cytokines was assessed using real-time PCR,western blot,and enzyme-linked immuno sorbent assay(ELISA).MiR-130a level was assessed using real-time PCR,and the target gene was identified using dual luciferase reporter assay.We demonstrated that apabetalone repressed Pg LPS-induced macrophage M1 polarization in a dose-dependent manner,as evidenced by decreased expression of inducible nitric oxide synthase(iNOS),CD86,and pro-inflammatory cytokines,and increased expression of Arg-1 and CD206.Mechanistically,Pg LPS increased miR-130a expression in macrophages,whereas apabetalone treatment repressed the effect.Functionally,forced expression of miR-130a promoted macrophage M1 polarization,and signal transducer and activator of transcription(STAT)-3 was the direct target gene of miR-130a in the process.Taken together,apabetalone decreases Pg LPS-induced macrophage M1 polarization via regulating miR-130a-3p/STAT3 axis,and may be a promising target for the clinical management of periodontitis.

Study on the mechanism of Porphyromonas gingivalis pili mediated ather osclerosis

Chronic periodontitis is the most common infectious periodontal disease caused by plaque biofilm.Pili is an important bacterial component of Porphyromonas gingivalis.Epidemiological studies have shown that chronic periodontitis can increase the risk of cardiovascular disease,and atherosclerosis is the pathological basis of cardiovascular disease.This article will summarize the mechanism of Porphyromonas gingivalis pili protein mediated chronic periodontitis and atherosclerosis,in order to expand new ideas of disease prevention and treatment.

Comparative Analysis in Vitro of the Application of blue m Oral Gel versus Chlorhexidine on Porphyromonas gingivalis:A Pilot Study

Oxygen is an essential nutrient for cellular metabolism, especially energy production. The substance is involved in multiple processes including oxidative killing of bacteria, reepithelialization, angiogenesis, and collagen synthesis. In order to test and compare the effects of the oxygen gel blue?m in vitro on Porphyromonas gingivalis, four groups were evaluated: 100% oxygen gel (B1), 75% oxygen gel (B2), 50% oxygen gel (B3), and 100% 0.12% chlorhexidine digluconate solution (C1). For this purpose, evaluations of the proportion of bacterial growth were performed, using the Agar diffusion test. The results demonstrated that blue?m at a dose of 100% and 75% is similar to chlorhexidine (p > 0.05);however blue?m at a concentration of 50% showed a lower inhibition halo when compared to chlorhexidine (p = 0.024). blue?m at higher concentrations provided inhibitory halo of Porphyromonas gingivalis similar to chlorhexidine digluconate, while blue?m at lower concentration had a lower bacterial inhibition halo compared to chlorhexidine.

Association between coinfection of Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans and Treponema denticola and periodontal tissue destruction in chronic periodontitis

Background The association between the infection of Porphyromonas gingivalis, Actinobacillus actinomy-cetemcomitans and Treponema denticola in chronic periodontitis (CP) and the severity of periodontal disease remains to be elucidated. The aim of this study was to investigate the subgingival infection frequencies of three periodontopathic bacteria in Chinese CP patients and to evaluate the correlations between infection by these bacteria and periodontal destruction.Methods A multiple PCR assay using primers derived from 16SrDNA genes of P. gingivalis, A. actinomy-cetemitans and T. denticola was established to measure simultaneously the presence of the three microbes in 162 subgingival samples from 81 Chinese CP patients. Results The positive rates of P. gingivalis, A. actinomycetemitans and T. denticola in the subgingival samples were 84.6%, 83.3% and 88.3%, respectively. Of the subgingival samples, 68% revealed the coinfection of all the three microbes. The infection rates with P. gingivalis, A. actinomycetemitans or T. denticola alone was 5.9% (1/17), 17.6% (3/17) and 76.5% (13/17), respectively. A close association was present between the A. actinomycetemitans infection and gingival index (GI) (P<0.01), but not between P. gingivalis or T. denticola infection and GI (P>0.05). P. gingivalis and A. actinomycetemitans were more frequently detectable in middle and deep pockets than in shallow ones (P<0.01), while T. denticola was found remarkably often in deep pockets (P<0.05). The coinfection rate of the three microbes was significantly higher in sites with severe periodontitis than in those with mild periodontitis (P<0.01). Conclusions The multiple PCR established in this study can be used as a sensitive and specific method to simultaneously detect all three microbes in subgingival samples. A. actinomycetemitans infection may be associated with CP and play an important role in the periodontal tissue destruction. The coinfection of P. gingivalis, A. actinomycetemitans and T. denticola can cause more serious periodontal destruction than infection of any one or two of the three microbes.

Suppression of inflammatory gene expression in T cells by Porphyromonas gingivalis is mediated by targeting MAPK signaling

There is increasing awareness of the effects of Porphyromonas gingivalis on host immune responses. Degradation of cytokines and chemokines by cysteine proteinases has previously been reported. However, the precise mechanisms by which P. gingivalis is able to alter intracellular signaling, and thus proliferation and inflammation, have not been descri bed. We have previously reported s u ppression of activator protei n-1 （AP-1） and degradation of I L-2 by protei nases from P. gingivalis. In the present study, we have analyzed the effects of P. gingivalis on Jurkat T-cell signal transduction and subsequent IL-2 and CXCL8 expression. We found that CXCL8, but not IL-2, gene expression levels were significantly suppressed by viable P. gingivalis. Analysis of intracellular signaling revealed an inhibitory effect of P. gingivalis on c-Jun and c-Fos, but not NFκB（p50and p65）, NFATor STAT5expression. This inhibitory effect was not due to suppression of mitogen-activated protein kinase （MAPK） （p38, erkand JNK） gene expression, but was rather due to prevention of protein kinase C （PKC） and p38 phosphorylation, as demonstrated by western blot analysis. Furthermore, SOCS1 and SOCS3 expression levels decreased following treatment of Jurkat T cells with viable P. gingivalis. The results indicate that P. gingivalis is able to suppress inflammatory gene expression by targeting the activity of MAPK pathways in T cells, which was confirmed by using specific inhibitors of NF-κB, PKC, ERK, p38 and JNK.

Inhibition and attenuation of pathogenicity of Porphyromonas gingivalis by leupeptin： A review

BACKGROUND： Porphyromonas gingivalis is a periodontal pathogen, which is considered to be a keystone pathogen for periodontitis. A diverse conglomerate of P. gingivalis virulence factors including lipopolysaccharide, fimbriae, capsular polysaccharide, haemagglutinin and cysteine proteases （Arg-gingipains and Lys-gingipain） are considered to be involved in the pathogenesis ofperiodontitis. Leupeptin is a cysteine protease inhibitor which is specific for Arg gingipains. The present review focuses on action of leupeptin on Arg gingipains. METHOD： A search was carried out systematically from the start till September, 2016. The search was made in Medline database via PubMed. The keywords enlisted were ＂leupeptin＂; ＂gingipains＂; ＂periodontitis＂ using Boolean operator ＂and.＂ RESULTS： The result was selection of 58 articles which linked leupeptin to periodontitis and gingipains; pathogenesis of periodontitis, pathogenicity of gingipains and role of leupeptin. CONCLUSION： It was concluded that leupeptin inhibits and attenuates a number of destructive activities of Arg gingipains including inhibition ofplatelet aggregation; inhibit degradation of LL-37, which is an antimicrobial peptide; blocking inhibition ofmonocyte chemoattractant protein; restoring level ofinterleukin-2; inhibiting degradation of collagen type I and IV to name a few.

Unraveling brain aging through the lens of oral microbiota

The oral cavity is a complex physiological community encompassing a wide range of microorganisms.Dysbiosis of oral microbiota can lead to various oral infectious diseases,such as periodontitis and tooth decay,and even affect systemic health,including brain aging and neurodegenerative diseases.Recent studies have highlighted how oral microbes might be involved in brain aging and neurodegeneration,indicating potential avenues for intervention strategies.In this review,we summarize clinical evidence demonstrating a link between oral microbes/oral infectious diseases and brain aging/neurodegenerative diseases,and dissect potential mechanisms by which oral microbes contribute to brain aging and neurodegeneration.We also highlight advances in therapeutic development grounded in the realm of oral microbes,with the goal of advancing brain health and promoting healthy aging.

Periodontopathogen profile of healthy and oral lichen planus patients with gingivitis or periodontitis

Oral lichen planus （OLP） is a chronic inflammatory disease that is frequently detected in oral tissues. The aim of our study was to identify the prevalence of the detection of periodontopathogenic microorganisms （Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia and Treponema denticola in OLP patients and to compare with this prevalence of periodontopathogenic microorganisms in healthy non-OLP patients. Our study included 27 （18 chronic periodontitis （OLPP） and 9 gingivitis （OLPG）） patients diagnosed with OLP along with 26 （13 chronic periodontitis （HP） and 13 gingivitis （HG）） healthy non-OLP patients. The multiplex polymerase chain reaction （PCR）with subsequent reverse hybridization method （micro-IDent） was used for identifying periodontopathogenic microorganisms present in subgingival plaque samples. The percentages of detection for A. actinomycetemcomitans, P. gingivalis, P. intermedia, T. forsythia and T. denticola in subgingival plaque samples taken from OLP patients （OLPG and OLPP） were 18.5%, 85.1%, 81.4%, 88.8% and 74%, respectively. Meanwhile, in the non-OLP patients （HG and HP）, these values were 7.6%, 50%, 46.1%, 73% and 57.7%, respectively. Thus, comparing the non-OLP groups with the OLP groups, the periodontopathogens＇ percentages of detection in the OLP groups were higher than those in the non-OLP groups. According to our study results, OLP patients have higher levels of infection with A. actinomycetemcomitans, P. gingivalis, P. intermedia, T. forsythia and T. denticola than non-OLP patients. We argue that the high percentages in patients with OLP may help identify the importance of periodontopathoRenic microorganisms in the progress of periodontal diseases of OLP.

Bacterial-killing Effect of Atmospheric Pressure Non-equilibrium Plasma Jet and Oral Mucosa Response

Recently, plasma sterilization has attracted increasing attention in dental community ibr the atmospheric pressure non-equilibrium plasma jet （APNPs）, which is driven by a kilohertz pulsed DC power, may be applied to the dental and oral diseases. However, it is still in doubt whether APNPs can effectively kill pathogenic bacteria in the oral cavity and produce no harmful effects on normal oral tissues, especially on normal mucosa. The aim of this study was to evaluate the bacterial-killing effect of APNPs in the biofilms containing a single breed of bacteria （Porphyromonas gingivalis, Pg.）, and the pathological changes of the oral mucosa after treatment by APNPs. P.g. was incubated to form the biofilms in vitro, and the samples were divided into three groups randomly： group A （blank control）; group B in which the biofilms were treated by APNPs （the setting of the equipment： 10 kHz, 1600 ns and 8 kV）; group C in which the biofilms were exposed only to a gas jet without ignition of the plasma. Each group had three samples and each sample was processed for up to 5 min. The biofilms were then fluorescently stained, observed and photographed under a laser scanning confocal microscope. In the animal experiment, six male Japanese white rabbits were divided into two groups randomly （n=3 in each group） in terms of the different post-treatment time （1-day group and 5-day group）. The buccal mucosa of the left side and the mucosa of the ventral surface of the tongue were treated by APNPs for 10 min in the same way as the bacterial biofilm experiment in each rabbit, and the corresponding mucosa of the other sides served as normal control. The clinical manifestations of the oral mucosa were observed and recorded every day. The rabbits were sacrificed one or five day（s） after APNPs treatment. The oral mucosa were harvested and prepared to haematoxylin and eosin-stained sections. Clinical observation and histopathological scores were used to assess mucosal changes. The results showed the obvious P.g. biofilms were formed at 10 days, and most of the bacteria in groups A and C were alive under a laser scanning confocal microscope, but the bacteria in the group B were almost all dead. In animal experiment, no ulcers, anabrosis and oral mucositis were found in both the 1-day and 5-day groups. The aver- age mucous membrane irritation index was -0.83 and -0.67 in the 1-day and 5-day groups, respectively, suggesting that no intense mucosal membrane irritation responses occurred. It was concluded that APNPs could effectively kill Pg. in the biofilms and did not cause any pathological changes in the normal mucosa, suggesting that the plasma jet （APNPs） may be applied to oral diseases as a novel sterilization device in the future.

Tyrosine phosphorylation and bacterial virulence

Protein phosphorylation on tyrosine has emerged as a key device in the control of numerous cellular functions in bacteria.In this article,we review the structure and function of bacterial tyrosine kinases and phosphatases.Phosphorylation is catalyzed by autophosphorylating adenosine triphosphate-dependent enzymes（bacterial tyrosine（BY） kinases） that are characterized by the presence of Walker motifs.The reverse reaction is catalyzed by three classes of enzymes：the eukaryotic-like phosphatases（PTPs） and dual-specific phosphatases;the low molecular weight protein-tyrosine phosphatases（LMW-PTPs）;and the polymerase-histidinol phosphatases（PHP）.Many BY kinases and tyrosine phosphatases can utilize host cell proteins as substrates,thereby contributing to bacterial pathogenicity.Bacterial tyrosine phosphorylation/dephosphorylation is also involved in biofilm formation and community development.The Porphyromonas gingivalis tyrosine phosphatase Ltp1 is involved in a restraint pathway that regulates heterotypic community development with Streptococcus gordonii.Ltp1 is upregulated by contact with S.gordonii and Ltp1 activity controls adhesin expression and levels of the interspecies signal AI-2.

Antimicrobial Activity of Traditional Chinese Medicines on Common Oral Bacteria

Objective: To evaluate twenty Traditional Chinese Medicines (TCM) against four oral bacteria. Methods: Twenty TCM were tested for sensitivity against Streptococcus mitis, Streptococcus sanguis, Streptococcus mutans and Porphyromonas gingivalis. Aliquots of suspension of each bacterial species were inoculated on a horse blood agar (HBA) plate, 6 mm diameter paper disks was soaked in different drug suspensions were placed concentrically on a HBA plate. Disks soaked in 0.2% w/v chlorhexidine were used as positive controls. These HBA plates were incubated for 48 hours anaerobically and the diameters of growth inhibition of three different areas were measured using a calibrated computer software and the mean diameter obtained for each bacteria. Broth microdilution assay was used to determine minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The experiment was repeated on three separate occasions. Results: The TCMs that consistently against Porphyromonas gingivalis, included Folium artemisiae argyi, Fructus crataegi, Rhizoma dryopteris crassirhizomae, Flos magnoliae, Rhizoma polygoni cuspidati, Radix scrophulariae ningpoensis, Galla chinensis, Radix scutellariae baicalensis and Rhizoma coptidis;against Streptococcus mutans included Fructus crataegi, Galla chinensis and Rhizoma copitidis;against Streptococcus mitis and Streptococcus sanguis included Galla chinensis and Rhizoma copitidis. Conclusion: Rhizoma copitidis and Galla chinensis had inhibitory effects on Streptococcus mitis, Streptococcus sanguis, Streptococcus mutans and Porphyromonas gingivalis in vitro.

食管癌与微生态的研究进展

食管癌(esophagus cancer, EC)主要包括食管腺癌和食管鳞状细胞癌(esophageal squamous cell carcinoma, ESCC)2种病理类型,是消化道常见恶性肿瘤之一,位居全球肿瘤发病率的第9位,死亡率第5位[1]。我国EC的发病率约占全球一半,ESCC比例超过90%。农村发病率较城市高,高发区与周边相对低发区形成鲜明对比,是我国EC典型的流行病学特征。EC早期通常无症状或症状轻微。