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Periodontitis is a multifactorial chronic inflammatory disease that destroy periodontium. Apart from microbial infection and host immune responses, emerging evidence shows aging and endoplasmic reticulum stress (ER stress) play a key role in periodontitis pathogenesis. The aim of this study is to identify aging-related genes (ARGs) and endoplasmic reticulum stress-related genes (ERGs) in periodontitis. Data were obtained from the Gene Expression Omnibus (GEO), Human Ageing Genomic Resources (HAGR) and GeneCards databases to identify differentially expressed mRNAs/miRNAs/lncRNAs (DEmRNAs/DEmiRNAs/DElncRNAs), ARGs and ERGs, respectively. We used the MultiMiR database for the reverse prediction of miRNAs and predicted miRNA-lncRNA interactions using the STARBase database. Afterwards, we constructed a mRNA-miRNA-lncRNA ceRNA network. A total of 10 hub genes, namely LCK, LYN, CXCL8, IL6, HCK, IL1B, BTK, CXCL12, GNAI1 and FCER1G, and 5 DEmRNAs-ARGs-ERGs were then discovered. Further, weighted gene co-expression network analysis (WGCNA) and single sample gene set enrichment analysis (ssGSEA) were performed to explore co-expression modules and immune infiltration respectively. Finally, we used transmission electron microscope (TEM), inverted fluorescence microscopy, quantitative real-time polymerase chain reaction (qRT-PCR) and Western Blot to verify the bioinformatic results in periodontal ligament stem cells (PDLSCs) infected with Porphyromonas gingivalis (P. gingivalis). The experimental results broadly confirmed the accuracy of bioinformatic analysis. The present study established an aging- and ER stress-related ceRNA network in periodontitis, contributing to a deeper understanding of the pathogenesis of periodontitis.

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OBJECTIVE: To investigate whether visceral adipose tissue-derived serine protease inhibitor (vaspin) can alleviate the inhibitory effect of high-glucose (HG) culture on the proliferation and osteogenic differentiation of human periodontal ligament stem cells (PDLSCs) and to preliminarily explore the underlying mechanisms. BACKGROUND: High glucose produces damage to the regeneration of periodontal tissue of PDLSCs. The expression level of vaspin in periodontal tissue is high in periodontitis patients and effectively reduced after initial therapy of periodontal diseases. However, the effect of vaspin on PDLSCs remains unknown. MATERIALS AND METHODS: PDLSCs were cultured in media augmented with 5.5 or 25.0 mM concentrations of glucose to elucidate the impact and mechanism of vaspin on PDLSCs under high glucose in vitro. Proliferation was measured by Cell Counting Kit-8 (CCK8) assay. Osteogenesis of PDLSCs was assessed by alkaline phosphatase (ALP) staining, ALP activity, and Alizarin Red staining. Quantitative real-time polymerase chain reaction (qRT-PCR) and western blot (WB) were used to investigate the osteo-specific markers. Then, the molecular impact of vaspin in the presence/absence of HG on PDLSCs physiology was determined with TGF-ß1/Smad signaling pathway as the main focus. RESULTS: It was revealed that the proliferation and osteogenic differentiation (OD) of PDLSCs under HG was reduced, and by adding vaspin the anti-osteogenic impact of HG was relieved. Moreover, vaspin enhanced TGF-ß1/Smad signaling pathway activity. Pretreatment with TGF-ß1 inhibitor blocked vaspin-triggered TGF-ß1/Smad signal activation and minimized the vaspin-induced protective effect against HG-inhibited growth and OD. CONCLUSIONS: In summary, vaspin observably reduces HG-mediated inhibition of PDLSCs OD by modulating the TGF-ß1/Smad signaling pathway. Vaspin may be a potential therapeutic for periodontal tissue regeneration in diabetic patients.

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AIM: Blood-brain barrier (BBB) disorder is one of the early findings in cognitive impairments. We have recently found that Porphyromonas gingivalis bacteraemia can cause cognitive impairment and increased BBB permeability. This study aimed to find out the possible key virulence factors of P. gingivalis contributing to the pathological process. MATERIALS AND METHODS: C57/BL6 mice were infected with P. gingivalis or gingipains or P. gingivalis lipopolysaccharide (P. gingivalis LPS group) by tail vein injection for 8 weeks. The cognitive behaviour changes in mice, the histopathological changes in the hippocampus and cerebral cortex, the alternations of BBB permeability, and the changes in Mfsd2a and Cav-1 levels were measured. The mechanisms of Ddx3x-induced regulation on Mfsd2a by arginine-specific gingipain A (RgpA) in BMECs were explored. RESULTS: P. gingivalis and gingipains significantly promoted mice cognitive impairment, pathological changes in the hippocampus and cerebral cortex, increased BBB permeability, inhibited Mfsd2a expression and up-regulated Cav-1 expression. After RgpA stimulation, the permeability of the BBB model in vitro increased, and the Ddx3x/Mfsd2a/Cav-1 regulatory axis was activated. CONCLUSIONS: Gingipains may be one of the key virulence factors of P. gingivalis to impair cognition and enhance BBB permeability by the Ddx3x/Mfsd2a/Cav-1 axis.

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This study aimed to investigate the effects of salivary histatin 5 (Hst5) on Porphyromonas gingivalis (P. gingivalis) biofilms in vitro and in vivo and the possible mechanisms. In in vitro experiments, P. gingivalis biomass was determined by crystal violet staining. Polymerase chain reaction, scanning electron microscopy, and confocal laser scanning microscopy were used to determine the Hst5 concentration. A search for potential targets was performed using transcriptomic and proteomic analyses. In vivo experimental periodontitis was established in rats to evaluate the effects of Hst5 on periodontal tissues. Experimental results showed that 25 µg/mL Hst5 effectively inhibited biofilm formation, and increased concentrations of Hst5 increased the inhibitive effect. Hst5 might bind to the outer membrane protein RagAB. A combination of transcriptomic and proteomic analyses revealed that Hst5 could regulate membrane function and metabolic processes in P. gingivalis, in which RpoD and FeoB proteins were involved. In the rat periodontitis model, alveolar bone resorption and inflammation levels in periodontal tissues were reduced by 100 µg/mL Hst5. This study showed that 25 µg/mL Hst5 inhibited P. gingivalis biofilm formation in vitro by changing membrane function and metabolic process, and RpoD and FeoB proteins might play important roles in this process. Moreover, 100 µg/mL Hst5 inhibited periodontal inflammation and alveolar bone loss in rat periodontitis via its antibacterial and anti-inflammatory effects. KEY POINTS: • Anti-biofilm activity of histatin 5 on Porphyromonas gingivalis was investigated. • Histatin 5 inhibited Porphyromonas gingivalis biofilm formation. • Histatin 5 showed inhibitory effects on the occurrence of rat periodontitis.

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OBJECTIVES: This paper aims to study the effect of the active form of vitamin D (calcitriol) on the internalized Porphyromonas gingivalis in macrophages and to assess the role of autophagy during this process. MATERIALS AND METHODS: Quantitative RT-PCR and bacteria culture were used to quantify live P. gingivalis internalized into U937-derived macrophages. Western blot assays were performed to detect the effect of P. gingivalis and calcitriol on autophagy in macrophages. Transmission electron microscope was used to observe the effect of calcitriol on the status of internalized P. gingivalis. Colocalization of P. gingivalis with the autophagosome and lysosome markers was observed by confocal laser scanning microscopy. RESULTS: Calcitriol caused a dose-dependent decrease in live P. gingivalis numbers and promoted both the endogenous and P. gingivalis-induced autophagy in macrophages. Calcitriol significantly promoted the destruction of P. gingivalis and the colocalization of P. gingivalis with autophagosome and lysosome markers. Conversely, with 3-MA, live P. gingivalis numbers in macrophages increased significantly and inhibition effect of calcitriol on the number of live P. gingivalis was attenuated. CONCLUSION: In U937-derived macrophages, calcitriol may promote colocalization of P. gingivalis with autophagosomes and lysosomes, namely autophagy process, to degrade live P. gingivalis.

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Porphyromonas gingivalis (P. gingivalis), one of the most important pathogens of periodontitis, is closely associated with the aggravation and recurrence of periodontitis and systemic diseases. Antibacterial peptide LL-37, transcribed from the cathelicidin antimicrobial peptide (CAMP) gene, exhibits a broad spectrum of antibacterial activity and regulates the immune system. In this study, we demonstrated that LL-37 reduced the number of live P. gingivalis (ATCC 33277) in HaCaT cells in a dose-dependent manner via an antibiotic-protection assay. LL-37 promoted autophagy of HaCaT cells internalized with P. gingivalis. Inhibition of autophagy with 3-methyladenine (3-MA) weakened the inhibitory effect of LL-37 on the number of intracellular P. gingivalis. A cluster of orthologous groups (COGs) and a gene ontology (GO) functional analysis were used to individually assign 65 (10%) differentially expressed genes (DEGs) to an "Intracellular trafficking, secretion, and vesicular transport" cluster and 306 (47.08%) DEGs to metabolic processes including autophagy. Autophagy-related genes, a tripartite motif-containing 22 (TRIM22), and lysosomal-associated membrane protein 3 (LAMP3) were identified as potentially involved in LL-37-induced autophagy. Finally, bioinformatics software was utilized to construct and predict the protein-protein interaction (PPI) network of CAMP-TRIM22/LAMP3-Autophagy. The findings indicated that LL-37 can reduce the quantity of live P. gingivalis internalized in HaCaT cells by promoting autophagy in these cells. The transcriptome sequencing and analysis also revealed the potential molecular pathway of LL-37-induced autophagy.

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OBJECTIVE: Epidemiological studies have shown a correlation between periodontal disease (PD) and age-related macular degeneration (AMD). However, the results have been inconsistent, and no relevant meta-analysis has been performed on this topic. Hence, we performed a meta-analysis to evaluate whether the two diseases are related. Material and Methods. The PubMed, Embase, Cochrane Library, and Web of Science databases were searched up to April 20, 2020, for related articles. Two authors independently conducted literature screening and data extraction and then used the Stata 15.1 software to calculate the relative risk (RRs) and 95% confidence intervals (CIs) to assess the association between PD and AMD. RESULTS: A total of 5 observational studies involving 112,240 participants and 5,005 AMD patients were included. The results of meta-analysis using the random-effects model showed that the incidence of AMD in PD patients was 1.35 times that of non-PD patients; the difference was statistically significant (RR = 1.35, 95%CI = 1.07-1.70, P = 0.011). Sensitivity analysis showed that the results were stable. CONCLUSIONS: PD patients have a higher risk of AMD, but the causal relationship between PD and AMD has not been confirmed. Further research should be carried out to verify the exact relationship between the two.

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OBJECTIVE: To ascertain the role of inducible nitric oxide synthase (iNOS) in the periodontitis response during diabetes. METHODS: Twenty-four male SD rats were randomly divided into four groups: control group (Control), diabetes mellitus group (D), diabetes mellitus plus periodontitis group (DP), and periodontitis group (P). Periodontitis and diabetes were established separately. Then the gingival tissue and alveolar bone were collected. A stereomicroscope was used to evaluate bone loss. The expression of iNOS, TNF-α, and NF-κB in the gingiva was detected by immunohistochemical staining, real-time PCR, and western blot analysis. RESULTS: Significant bone loss was observed in the DP and P groups and more extensive bone resorption was discovered in the DP group than in the P group (P < 0.05). The immunohistochemical staining analysis revealed enhanced expression of iNOS located in the gingiva of the three disease groups compared with the control group (P < 0.05). In particular, the level of iNOS was significantly higher in the DP group than in the P group (P < 0.05). This elevated trend of iNOS was further demonstrated by quantitative PCR and western blot analysis. Similarly, the mRNA and protein expression levels of NF-κB in the D, DP, and P groups were significantly higher than those of the control group, as was the level of TNF-α protein (P < 0.05). CONCLUSIONS: Our results proved diabetes exacerbated alveolar bone resorption in a periodontitis rat model. iNOS may be the inflammatory mediator in the course of periodontal injury promoted by diabetes.

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BACKGROUND: The present study aimed to explore the effects of the active form of vitamin D (calcitriol, 1α,25-dihydroxyvitamin D3 , 1α,25 (OH)2 D3 , 1,25D) on live Porphyromonas gingivalis internalized into KB cells and U937 cells. METHODS: Quantitative real-time polymerase chain reaction method was used to evaluate the number of surviving P. gingivalis internalized into KB cells and U937 cells. Transmission electron microscopy was used to detect P. gingivalis in cells. A western blot analysis was performed to observe LC3 expressions. RESULTS: 1) Treatment with 1,25D decreased the number of live P. gingivalis in KB cells and U937 cells in a dose-dependent manner. 2) Dividing P. gingivalis were found only in KB cells but not in U937 cells. The cell walls of most P. gingivalis in KB cells were intact, while those in U937 cells were disrupted. Treatment with 1,25D promoted the encapsulation of P. gingivalis in autophagosomes in both KB and U937 cells. 3) Both 1,25D treatment and P. gingivalis infection increased the LC3 II/I ratio. Furthermore, 1,25D treatment increased the P. gingivalis-upregulated LC3 II/I ratio. 4) Treatment with 3-methyladenine (3-MA) decreased the number of P. gingivalis by 11.41% in KB cells, while increased that by 121.51% in U937 cells. Under 1,25D treatment conditions, 3-MA treatment increased the number of P. gingivalis by 88.71% in KB cells and by 284.70% in U937 cells. CONCLUSIONS: Autophagy may facilitate P. gingivalis survival in KB cells and eliminate P. gingivalis in U937 cells. Treatment with 1,25D may help decrease the number of live P. gingivalis in KB cells and U937 cells by promoting functional autophagy.

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Recent epidemiological studies have revealed that Porphyromonas gingivalis, a major pathogen in periodontal disease, is associated with the development of oral squamous cell carcinoma (OSCC). However, the underlying mechanisms induced by P. gingivalis have not been well-defined. We aimed to determine the role of P. gingivalis in OSCC proliferation and the relevant molecular mechanisms. A cellular proliferation model of OSCC Tca8113 cells infected by P. gingivalis at a multiplicity of infection (MOI) of 50 was established. Cell proliferation was drastically increased in the infected cells compared with the control cells, while the proportion of cells in S phase was increased and the proportion of cells in G1 phase was decreased in the infected cells compared with the control cells. Additionally, the levels of activator protein 1 (AP-1; c-Jun and c-Fos) and its target gene cyclin D1 were increased in P. gingivalis-infected Tca8113 cells compared with control cells. miR-21 expression was elevated when programmed cell death 4 (PDCD4) expression was downregulated. Cyclin D1 expression was regulated by miR-21, PDCD4, and AP-1. The disruption of the pathway by silencing c-Jun, blocking miR-21 expression, or overexpressing PDCD4 led to decreased cyclin D1 expression and inhibited cell proliferation. P. gingivalis DNA levels were positively correlated with miR-21 and c-Jun expression and negatively correlated with PDCD4 expression in clinical OSCC samples. Our findings indicated that P. gingivalis might promote OSCC proliferation by regulating cyclin D1 expression via the miR-21/PDCD4/AP-1 negative feedback signaling pathway.

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BACKGROUND: The aim of this study was to evaluate the relationship among clinical periodontal, microbiologic parameters and lung function in participants with chronic obstructive pulmonary disease (COPD). METHODS: A total of 160 participants were recruited, including 80 participants with COPD (COPD group) and 80 participants without COPD (control group). All participants completed questionnaires and underwent clinical periodontal and lung function examinations. Subgingival plaques were obtained to determine the prevalence of selected oral and respiratory bacterial species. RESULTS: 1) Significant relationships were noted in the participants among oral hygiene index-simplified (OHI-S), clinical attachment level (CAL) and forced expiratory volume in one second (FEV1%). 2) Porphyromonas gingivalis (Pg), Klebsiella pneumonia (Kp), Pseudomonas aeruginosa (Pa) and Streptococcus pneumonia (Sp) prevalence was increased in participants with COPD compared with control participants. 3) A significant negative association was noted between the relative content of Pg and FEV1% in participants with COPD. CONCLUSION: The results of this study confirm that periodontal destruction and oral pathogens are associated with lung function.

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OBJECTIVES: Lots of bioactive materials have been additionally applied for the treatment of periodontal intrabony defect. However, there is dearth of studies to systematically evaluate the supplementary role of them in periodontal regeneration. The goal of this meta-analysis is to evaluate the adjunctive effects of bioactive materials such as platelet-rich plasma (PRP), platelet-rich fibrin (PRF), enamel matrix derivative (EMD), and amnion membrane (AM) on the outcomes of bone grafting treatment for periodontal intrabony defects. METHODS: Articles published before December 2017 were searched electronically in three databases (PubMed, Embase, and Cochrane Central), with no date or language limits. Randomized controlled trials (RCTs) on the assessment of effectiveness of the four biomaterials in conjunction with demineralized freeze-dried bone allografts (DFDBA) in the treatment of periodontal intrabony defects were enrolled in this meta-analysis. Data were analyzed with STATA 12. RESULTS: Nine studies were included. PRF and PRP significantly improved pocket depth (PD) reduction and clinical attachment loss (CAL) gain. Only PRF exhibited a positive result in recession reduction (RecRed). Only PRP showed a statistically significant increase in bone fill. AM merely gained more CAL. EMD did not improve any clinical outcome. CONCLUSION: Our data suggest that PRF/PRP could be taken as a preferred adjunct to facilitate periodontal regeneration of intrabony defects.

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BACKGROUND: Porphyromonas gingivalis is strongly associated with the development, progression, severity and recurrence of periodontitis. Periodontal ligament stem cells (PDLSCs) play an important role in the maintenance of periodontal tissue self-renewal and repair. The purpose of this study was to investigate the ability of P. gingivalis to infect PDLSCs using an in vitro monolayer model. METHODS: We separated and cultured primary PDLSCs using the tissue block with limiting dilution method. The efficiency of P. gingivalis (ATCC 33277) infection of PDLSCs was measured using agar plate culture and quantitative polymerase chain reaction (q-PCR) methods. PDLSCs infected with P. gingivalis were also observed by transmission electron microscopy. RESULTS: We assessed stem cell properties including cell morphology, clone formation, growth activity, cell surface antigens and multiple differentiation capacity. The infection rates of P. gingivalis in PDLSC at MOIs of 50, 100, 200, and 500 were 5.83%, 8.12%, 7.77% and 7.53% according to the agar plate culture method. By q-PCR, the efficiencies of P. gingivalis infection of PDLSCs at MOIs of 50, 100, 200, and 500 were 6.74%, 10.56%, 10.36% and 9.78%, respectively. Overall, the infection efficiency based on q-PCR was higher than that according to agar plate culture. Using transmission electron microscopy, we verified that P. gingivalis (ATCC 33277) could infect and invade PDLSCs after 2 h of incubation, and endocytic vacuoles were not found surrounding the internalized bacteria. CONCLUSIONS: In conclusion, our data demonstrate that P. gingivalis can invade PDLSCs.

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OBJECTIVE: This study used con-beam computed tomography (CBCT) to investigate the prevalence and severity of alveolar bone loss in middle-aged (40-59 years) Chinese with chronic periodontitis. MATERIALS AND METHODS: The study group comprised 145 dentate individuals aged 40 to 59 years residing in China who suffered from chronic periodontitis. CBCT and the application of NNT software were used to examine the level and location of alveolar bone loss. RESULTS: The study revealed that 40-59 year old patients with chronic periodontitis had severe bone loss. At 5,286 sites (34.7%), alveolar bone loss was mild; severe alveolar bone loss was found at 5,978 sites (39.2%). A comparison of bone loss in different jaws revealed that the area with the highest degree of bone loss was on the lingual side of the maxillary molar (56.3 ± 7.2%), and that the area with the lowest degree was primarily on the lingual side of the mandibular canine (27.5 ± 6.3%). There was a lower degree of alveolar bone loss in males than females. Differences were observed when comparing the incidence of bone loss between males and females (P < 0.05). Menopause in females and smoking in both genders may affect the level of bone loss. Male smokers experienced a greater degree of bone loss (41.67 ± 5.76%) than male non-smokers (32.95 ± 4.31%). A 42.23 ± 6.34% bone loss was found in menopausal females versus 31.35 ± 3.62% in non-menopausal females. CONCLUSIONS: The study revealed that different sites and teeth exhibited a diverse degree of bone loss. In middle-aged patients with chronic periodontitis, the highest degrees of bone loss in the incisors, premolars, and molars were on the lingual side, mesial side and lingual side, respectively. Menopause in females and smoking may affect the level of bone loss.

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OBJECTIVE: The infection of Porphyromonas gingivalis (P. gingivalis) modulates host immune-inflammatory responses and destructs homeostasis of normal cell cycle, thereby leading to periodontal tissue destruction. Human periodontal ligament fibroblasts (PDLFs) are key players in the host immune responses and periodontal tissue regeneration. The aim of the present study was to discover the effects of P. gingivalis infection on the cell cycle and inflammatory cytokine production in PDLFs. DESIGN: P. gingivalis infection model into PDLFs was established. The effect of P. gingivalis on the cell proliferation and cell cycle were detected by MTT and flow cytometry. The p21, cyclin D1 and cyclin E mRNA expression, p21 protein expression, as well as IL-6 and IL-8 protein levels were analyzed by RT-qPCR, Western blot and ELISA, respectively. RESULTS: P. gingivalis promoted proliferation and G1 phase of PDLFs. G1 phase promotion was associated with the decreased level of p21 and the up-regulation of cyclin D1 at 6h, and with the increased level of cyclin E at 12h. Simultaneously, the immune-inflammatory response of PDLFs was initiated by P. gingivalis during the initial stage of infection, including the increased expressions of IL-6 and IL-8. CONCLUSION: We confirmed that the infection of P. gingivalis could modulate the expression of PDLF genes, which control cell cycle and inflammatory cytokine production. Thus, P. gingivalis may contribute to the proliferation and inflammation of periodontal tissue.

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BACKGROUND: The development of chronic periodontitis was due to not only periodontal pathogens, but also the interaction between periodontal pathogens and host. The aim of this study is to investigate the alterations in gene expression in Porphyromonas gingivalis (P.gingivalis) W83 after inoculation in rat oral cavity. RESULTS: P.gingivalis W83 inoculation in rat oral cavity caused inflammatory responses in gingival tissues and destroyed host alveolar bone. Microarray analysis revealed that 42 genes were upregulated, and 22 genes were downregulated in the detected 1786 genes in the inoculated P.gingivalis W83. Real-time quantitative PCR detection confirmed the expression alterations in some selected genes. Products of these upregulated and downregulated genes are mainly related to transposon functions, cell transmembrane transportation, protein and nucleic acid metabolism, energy metabolism, cell division and bacterial pathogenicity. CONCLUSIONS: P.gingivalis W83 has a pathogenic effect on host oral cavity. Meanwhile, inflammatory oral environment alters P.gingivalis W83 gene expression profile. These changes in gene expression may limit the proliferation and weaken the pathogenicity of P.gingivalis W83, and favor themselves to adapt local environment for survival.

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Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) is a Gram-negative bacterium which is implicated in the pathogenesis of human periodontal disease and in particular aggressive periodontitis. Virulence factors from A. actinomycetemcomitans have been shown to induce apoptosis of osteoblasts, however, the underlying mechanisms of the induction of apoptosis are poorly understood. In the present study, the infection of A. actinomycetemcomitans in human osteoblastic MG63 cells was established. Accordingly, A. actinomycetemcomitans infection enhanced significant apoptosis of MG63 cells. We found that both expression levels of NLRP3 and ASC were increased dramatically after MG63 cell cultures exposed to A. actinomycetemcomitans. Moreover, the secretion of mature interleukin-1ß (IL-1ß) and IL-18 were extensively induced in A. actinomycetemcomitans-infected cells as compared with non-invasion group of MG63 cell cultures, indicating the activation of the NLRP3 inflammasome during infection. Finally, we found that the knockdown expression of NLRP3 by specific small interfering RNA (siRNA) attenuated apoptosis of A. actinomycetemcomitans-infected MG63 cells. Our data suggest that A. actinomycetemcomitans promotes apoptosis of human osteoblasts at least partially through the NLRP3 inflammasome.

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Pseudomonas aeruginosa is an important opportunistic bacterial pathogen, causing infections of respiratory and other organ systems in immunocompromised hosts that may invade and proliferate in mucosal epithelial cells to induce apoptosis. Previous studies suggest that oral bacteria, especially gram-negative periodontal pathogens, may enhance P. aeruginosa invasion into respiratory epithelial cells to augment tissue destruction. In this study, we investigated the effect of the periodontopathogen Porphyromonas gingivalis on P. aeruginosa-induced epithelial cell apoptosis. P. gingivalis invasion transiently inhibited P. aeruginosa-induced apoptosis in respiratory epithelial cells via the signal transducer and activator of transcription 3 (STAT3) signaling pathway. The activated STAT3 up-regulated the downstream anti-apoptotic moleculars survivin and B-cell leukemia-2 (bcl-2). This process was accompanied by down-regulation of pro-apoptosis molecular Bcl-2-associated death promoter (bad) and caspase-3 activity inhibition. In addition, the activation of the STAT3 pathway was affected by P. gingivalis in a dose-dependent manner. Finally, co-invasion of P. aeruginosa and P. gingivalis led to greater cell death compared with P. aeruginosa challenge alone. These results suggest that regulation of P. aeruginosa-induced apoptosis by P. gingivalis contributes to the pathogenesis of respiratory disease. Interference with this process may provide a potential therapeutic strategy for the treatment and prevention of respiratory disease.

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OBJECTIVE: To detect Porphyromonas gingivalis (P. gingivalis) in buccal epithelial cells and subgingival plaque from periodontally healthy subjects and patients with chronic periodontitis. METHODS: 40 subjects were included in the healthy group and 39 subjects were included in the diseased group in this study. Cells and subgingival plaque samples were collected. The extracted DNA was amplified with universal primers and P. gingivalis species-specific primer. RESULTS: P. gingivalis was detected in 37.5% of subgingival plaque samples and 32.5% of buccal mucosa samples in the healthy subjects, but 69.23% of subgingival plaque samples and 46.15% of buccal mucosa samples in the periodontitis group. Highly statistically significant differences were observed between healthy and periodontitis groups in the detections of P. gingivalis of subgingival plaque samples. CONCLUSION: P. gingivalis may be one of oral flora because it can be detected in the healthy population and not lead to destruction of supporting structures of the teeth.

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