Porphyromonas gingivalis Induces Chronic Kidney Disease through Crosstalk between the NF-κB/NLRP3 Pathway and Ferroptosis in GMCs

Objective Porphyromonas gingivalis(P.gingivalis)is a gram-negative bacterium found in the human oral cavity and is a recognized pathogenic bacterium associated with chronic periodontitis and systemic diseases,including chronic kidney disease(CKD),but the roles and molecular mechanism of P.gingivalis in CKD pathogenesis are unclear.Methods In this study,an animal model of oral P.gingivalis administration and glomerular mesangial cells(GMCs)cocultured with M1-polarized macrophages and P.gingivalis supernatant were constructed.After seven weeks of P.gingivalis gavaged,peripheral blood was collected to detect the changes in renal function.By collecting the teeth and kidneys of mice,H&E staining and IHC were used to analyze the expression of periodontal inflammatory factors in mice,PAS staining was used to analyze glomerular lesions.The supernatant of macrophages was treated with 5%P.gingivalis supernatant.H&E staining,IHC,Western blot and RT-PCR were applied to analyze renal inflammatory factors,macrophage M1 polarization,NF-κB,NLRP3 and ferroptosis changes in vitro.Results We found that oral P.gingivalis administration induced CKD in mice.P.gingivalis supernatant induced macrophage polarization and inflammatory factor upregulation,which triggered the activation of the NF-κB/NLRP3 pathway and ferroptosis in GMCs.By inhibiting the NF-κB/NLRP3 pathway and ferroptosis in GMCs,cell viability and the inflammatory response were partially alleviated in vitro.Conclusion We demonstrated that P.gingivalis induced CKD in mice by triggering crosstalk between the NFκB/NLRP3 pathway and ferroptosis in GMCs.Overall,our study suggested that periodontitis can promote the pathogenesis of CKD in mice,which provides evidence of the importance of periodontitis therapy in the prevention and treatment of CKD.

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.

Porphyromonas gingivalis and digestive system cancers

Porphyromonas gingivalis(P. gingivalis) is an anaerobic gram-negative bacterium that colonizes in the epithelium and has been strongly associated with periodontal disease. Recently, various degrees of associations between P.gingivalis and digestive system cancers, including oral squamous cell carcinoma in the oral cavity, oesophageal squamous carcinoma in the digestive tract, and pancreatic cancer in pancreatic tissues, have been displayed in multiple clinical and experimental studies. Since P. gingivalis has a strong association with periodontal diseases, not only the relationships between P. gingivalis and digestive system tumours but also the effects induced by periodontal diseases on cancers are well-illustrated in this review. In addition, the prevention and possible treatments for these digestive system tumours induced by P. gingivalis infection are also included in this review. At the end, we also highlighted the possible mechanisms of cancers caused by P. gingivalis. One important carcinogenic effect of P. gingivalis is inhibiting the apoptosis of epithelial cells,which also plays an intrinsic role in protecting cancerous cells. Some signalling pathways activated by P. gingivalis are involved in cell apoptosis, tumourigenesis,immune evasion and cell invasion of tumour cells. In addition, metabolism of potentially carcinogenic substances caused by P. gingivalis is also one of the connections between this bacterium and cancers.

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.

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.

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.

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.

Debridement Effect on Periodontal Pathogen <i>Porphyromonas gingivalis</i>Cultured on Titanium by Application of Atmospheric-Pressure Plasma

The debridement treatments of dental implants are very important in long-term maintenance after implant placement in a patient. Deposition of periodontal pathogens around the implant surface has a high risk of causing periimplantitis. The aim of this study was to evaluate the extent of elimination of Porphyromonas gingivalis, known as representative periodontopathic bacteria, from titanium, which has been the main material used for dental implants. Assuming that the debridement processing of dental implants removes periodontal bacteria, one of the methods for removing bacteria deposited on titanium is considered to be plasma irradiation. Irradiation with atmospheric-pressure plasma was carried out against periodontopathic bacteria cultured and deposited on the surface of a titanium disk. After the plasma irradiation, the reduction of the number of bacteria re-cultured for 24 hours was evaluated. The number of viable bacteria on the titanium surface was estimated by an ATP-bioluminescent assay. Viable cells after the plasma irradiation were reduced to 1.5% or less compared to the untreated group. As one of the methods of debridement in general dental treatments, atmospheric-pressure plasma has proved to be an effective method to remove adverse prognostic factors in dental patients.

Increased Expression of 11<i>β</i>-Hydroxysteroid Dehydrogenase Type 1 in Experimental Periodontitis Induced by Lipopolysaccharide from <i>Porphyromonas gingivalis</i>

It has been proposed that 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1), which activates glucocorticoids, plays a role in chronic inflammatory diseases including metabolic diseases, rheumatoid arthritis, and ulcerative colitis. We have recently reported that the expression of 11β-HSD1 is increased in the gingiva of patients with chronic periodontitis and in that of rats with ligature-induced periodontitis. In this study, to further demonstrate the involvement of 11β-HSD1 in chronic periodontitis, the expression of 11β-HSD1 was investigated in another rat model of experimental periodontitis induced by intragingival injection of lipopolysaccharide from Porphyromonas gingivalis (LPS-PG). Alveolar bone loss was observed two weeks after intragingival injection of LPS-PG. The level of 11β-HSD1 mRNA assessed by real-time reverse transcriptase-polymerase chain reaction was significantly elevated in LPS-PG-induced periodontitis compared with controls. The expression of 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2), which inactivates glucocorticoids, was not significantly different between control and LPS-PG-induced periodontitis. The expression of 11β-HSD1 was significantly correlated with that of TNF in LPS-PG-induced periodontitis. The increased expression of 11β-HSD1 protein in LPS-PG-induced periodontitis was confirmed by immunohistochemistry using anti-11β-HSD1 antibody. These results further suggest a role for 11β-HSD1 in the pathogenesis of chronic periodontitis.

SspB Peptide Assay Reveals Saliva-Mediated <i>Porphyromonas gingivalis</i>Attachment

Background: Porphyromonas gingivalis is a major periodontal pathogen that binds efficiently to Streptococcus gordonii, which in turn binds to salivary agglutinin (gp340). The SspB of S. gordonii appears to mediate this association. We previously reported that the strepto-coccal SspB peptide analog, designated SspB (390-T400K-402), showed high binding activity with saliva. To understand the three-way interaction among S. gordonii, P. gingivalis and salivary gp340 as a unit, we established a peptide binding assay using SspB (390-T400K-402). Methods: The binding activity of the SspB (390-T400K-402) to P. gingivalis was detected by ELISA. Ninety-six well plates were coated with whole bacterial cell (P. gingivalis strains ATCC 33277, and W83;S. gordonii DL1) in Na2CO3 coating buffer. After blocking, bacterial cells were incubated with saliva or salivary agglutinin peptide (SRCRP2). Biotinylated SspB (390-T400K-402) was applied and incubated with 1:1000 streptoavidin-conjugated alkaline phosphatase. After development, A405 was recorded. Results: P. gingivalis 33277 showed the highest binding activity of the tested bacteria, whereas P. gingivalis W83, which was deficient in Mfa1 fimbriae, exhibited poor binding activity, as did S. gordonii. The binding of SspB (390-T400K-402) peptide in saliva- or SRCRP2-treated P. gingivalis was significantly higher than that in non-treated cells. Conclusion: The SspB (390-T400K-402) peptide binding assay revealed that initial attachment of P. gingivalis to the substrata of S. gordonii may require gp340-mediated SspB-Mfa1 interactions. The assay is available to assess the relationships among SspB, Mfa1 and salivary gp340 as a unit.

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.

Porphyromonas gulae infection in canines,pet owners and veterinarians in China:an epidemiological study and risk factor analysis

Porphyromonas gulae is a clinically prevalent,anaerobic,oral bacteria in canines,that may be a causative agent of canine periodontal disease,and a potential threat to human oral health.Research on P.gulae pathogenicity in canines,their owners,and veterinarians is lacking in China.This study aimed to determine the isolation and detec-tion rates of P.gulae in gingival crevicular fluid(GCF)samples from 101 canines in Beijing,using anaerobic culture techniques and 16S rRNA gene sequencing.The main risk factors for the transmission of P.gulae from canines to humans were also analyzed through analyzing the statistical data on risk factor variables from 103 canine owners and 60 veterinarians in Beijing who tested positive for P.gulae detection in GCF samples.The isolation and detection rates of P.gulae in canines were 31.5%(29/92)and 92.1%(93/101),respectively,compared with detection rates of 24.3%(25/103)in canine owners,43.3%(26/60)in veterinarians,and 52.0%(13/25)in dentists.The degree of contact with canines(P=0.001,P<0.01)and smoking(P=0.021,P<0.05)were significant risk factors for P.gulae detection in owners.Moreover,the degree of contact during ultrasonic scaling(P=0.065,0.05<P<0.1)was the most important risk factor for the positive detection of P.gulae in veterinarians.These findings suggest that P.gulae may colonize the human oral cavity through intimate contact with canines or participation in dental ultrasonic scaling operations.

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.

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.