Porphyromonas gingivalis-Induced NLRP3 Inflammasome Activation and Its Downstream Interleukin-1ß Release Depend on Caspase-4.

Background: Oral commensals contribute to microbe-host symbiosis in periodontal homeostasis, and Porphyromonas gingivalis (P. gingivalis) as the keystone pathogen critically accounts for the shift of symbiosis to dysbiosis and periodontal destruction. Nucleotide-binding oligomerization domain (NOD)-like receptor (NLR) family pyrin domain containing 3 (NLRP3) inflammasome-mediated interleukin-1ß (IL-1ß) is significantly involved in periodontal diseases, and notably P. gingivalis enables to modulate the induction and expression of NLRP3. Whereas, the exact mechanism by which NLRP3 inflammasome is regulated in response to commensal and pathogenic bacteria remains unclear. Methods: To examine the expression of IL-1ß and NLRPs inflammasome in tissues with severe chronic periodontitis, and further investigate how Caspase-4-dependent non-canonical NLRP3 inflammasome pathways functioned during the interactions of Streptococcus mitis (S. mitis) and P. gingivalis with human THP-1 cells. Results: IL-1ß and NLRP3, NLRP6, NLRP12, and absent in melanoma 2 (AIM2) inflammasomes are highly expressed in gingival tissues with severe chronic periodontitis. In human THP-1 cells, P. gingivalis activates the synthesis and secretion of IL-1ß to higher levels than S. mitis. Importantly, NLRP3-, Caspase-1-, and Caspase-4-siRNA knockdown THP-1 cells treated with P. gingivalis exhibited a lower expression level of IL-1ß as compared to the control cells. In addition, silencing of either CASP4 or CASP1 can lead to a concurrent or reciprocal decrease in the expression of the other. Of note, the IL-1ß induction is not affected in the S. mitis-treated THP-1 cells with the silence of NLRP3, Caspase-1, and Caspase-4 genes. Conclusion: NLRP3/Caspase-4 and NLRP3/Caspase-1 dependent IL-1ß production may crucially contribute to the dysregulated immuno-inflammatory response in periodontal pathogenesis.

Periodontal Commensals and Pathogens Differentially Modulate Immuno-Inflammatory Response in Human Oral Keratinocytes.

OBJECTIVE: To investigate the immunoinflammatory response in the crosstalk of human oral keratinocytes (HOKs) with selected periodontal commensals and pathogens. METHODS: Four representative viable oral bacteria, including periodontal commensals (Streptococcus mutans, Sm; and Actinomyces israelii, Ai) and pathogens (Aggregatibacter actinomycetemcomitans, Aa; and Porphyromonas gingivalis, Pg), were selected. A viable bacteria-HOKs interactive model was tested under various conditions of oxygen, antibiotics, duration and multiplicity of infection (MOI). The expression of IL-6 and IL-8 in HOKs was assessed by real-time qPCR and ELISA. RESULTS: An MOI of 1 was determined to be the appropriate ratio of bacteria and HOKs with substantial amounts of viable bacterial cells and HOKs in an antibiotic-free medium under aerobic conditions for 2 h. Sm and Pg significantly upregulated the expression of IL-6 and IL-8 (P < 0.05), while Ai and Aa could not induce significant levels of these cytokines with reference to the control. CONCLUSION: Within the limitations of this study, the current findings suggest that periodontal commensals and pathogens may differentially modulate immunoinflammatory response in human oral keratinocytes.

Salivary microbiome in non-oral disease: A summary of evidence and commentary.

OBJECTIVE: The advent of high-throughput sequencing and 'omic' technologies is facilitating an 'open-ended' understanding of the human microbial community and its interplay with health. This commentary aims to present key perspectives and summarize current evidence from metagenomic studies of salivary microbiota in relation to general health and systemic diseases. DESIGN: A narrative review of studies that described salivary microbiome composition in relation to various general health conditions was conducted and the main results were summarized. RESULTS: Currently available evidence shows salivary microbial patterns and fingerprints as related to a range of metabolic, autoimmune and immunodeficiency associated conditions, similar to albeit at a far lower scale than similar studies in the gut microbiome. CONCLUSIONS: Considering the relative ease of collection, emerging evidence of association with non-oral diseases may imply that saliva microbiome research may have potential diagnostic or prognostic value.

Teeth under High Occlusal Force may Reflect Occlusal Trauma-associated Periodontal Conditions in Subjects with Untreated Chronic Periodontitis.

OBJECTIVE: To determine the association of high occlusal force (HOF) with the signs of occlusal trauma and periodontal conditions in periodontitis patients, and elaborate the relevant clinical implications. METHODS: Periodontal parameters and signs of occlusal trauma were recorded for 807 teeth in 30 subjects with untreated chronic periodontitis. The T-scan II occlusal analysis system determined the HOF during maximum intercuspation, lateral excursion and protrusive excursion. The correlation of HOF with periodontal parameters and signs of occlusal trauma was analysed. RESULTS: Overall, the teeth with HOF existed mainly in molars and presented with deeper probing depth (PD) and higher frequency of bleeding on probing (BOP) than those without HOF. The fixed-effect analysis showed that HOF was positively correlated with PD and BOP (P < 0.05) in posterior teeth; widened periodontal ligament space on radiographs in upper (r = 0.179, P < 0.01) and lower posterior teeth (r = 0.205; P < 0.05); as well as functional mobility in upper posterior teeth (r = 0.168; P < 0.05). CONCLUSION: This study suggests that the posterior teeth with HOF in subjects with chronic periodontitis may reflect occlusal trauma-associated periodontal conditions that could probably increase the risk of further periodontal destruction. These findings may improve the clinical assessment of occlusal trauma and related periodontal conditions for better patient management and treatment outcomes.

Detection of survivin, carcinoembryonic antigen and ErbB2 level in oral squamous cell carcinoma patients.

INTRODUCTION: The aim of this study was to detect the survivin, carcinoembryonic antigen (CEA) and ErbB2 in the saliva, serum and local tumor-exfoliated cells of oral squamous cell carcinoma (OSCC) patients, for providing reliable tumor markers for the early detection of oral malignant cancer. MATERIALS AND METHODS: The saliva, serum, and local tumor-exfoliated cell samples of 26 OSCC patients without chemotherapy and 10 non-cancer patients were collected in Department of Oral and Maxillofacial Surgery, School of Stomatology, Peking University. The contents of survivin, CEA and ErbB2 using were detected usingenzyme-linked immunosorbent assay. RESULTS: The survivin and CEA levels in saliva and local tumor-exfoliated cells of OSCC patients were significantly higher than those in the non-cancer patients (P < 0.05), but there was no significant difference in the content of the above factors in the serum sample between two groups. There was no significant difference in the ErbB2 content in the saliva, serum or local tumor-exfoliated cells between two groups. CONCLUSION: Survivin and CEA levels are significantly increased in the saliva and local tumor-exfoliated cells in OSCC patients, and they can be used as reliable markers for the early detection of oral malignant cancer.

Clonality of bacterial consortia in root canals and subjacent gingival crevices.

AIM: No oral niche can be considered to be segregated from the subjacent milieu because of the complex community behavior and nature of the oral biofilms. The aim of this study was to address the paucity of information on how these species are clonally related to the subjacent gingival crevice bacteria. METHODS: We utilized a metagenomic approach of amplifying 16S rDNA from genomic DNA, cloning, sequencing and analysis using LIBSHUFF software to assess the genetic homogeneity of the bacterial species from two infected root canals and subjacent gingival crevices. RESULTS: The four niches studied yielded 186 clones representing 54 phylotypes. Clone library comparisons using LIBSHUFF software indicated that each niche was inhabited by a unique flora. Further, 42% of the clones were of hitherto unknown phylotypes indicating the extent of bacterial diversity, especially in infected root canals and subjacent gingival crevices. CONCLUSIONS: We believe data generated through this novel analytical tool shed new light on understanding oral microbial ecosystems.

Effect of glycine powder air-polishing as an adjunct in the treatment of peri-implant mucositis: a pilot clinical trial.

BACKGROUND: Glycine powder air-polishing (GPAP) has the potential to effectively erase biofilms and may improve the treatment efficacy of peri-implant mucositis. This pilot clinical trial evaluated the effect of GPAP as an adjunct in treating peri-implant mucositis. MATERIALS AND METHODS: Twenty-four subjects having at least one implant with peri-implant mucositis were randomly assigned to test (12 subjects with 17 implants) and control (12 subjects with 16 implants) groups. Following baseline assessment, all subjects received oral hygiene instruction and non-surgical debridement. In the test group, the sites with probing depth (PD) ≥4 mm were additionally treated by GPAP for 5 sec. Clinical parameters were measured at 1-week, 1-month, and 3-month recall visits. RESULTS: At the 3-month visit, the mean reductions in PD at site level were 0.93 ± 0.93 mm and 0.91 ± 0.98 mm in the test and control groups, respectively (P < 0.05), and no significant difference existed between two groups. Mean bleeding score was also significantly reduced in both groups after the intervention. No complications or discomfort were reported during the study. CONCLUSIONS: This pilot clinical trial suggests that non-surgical mechanical debridement may effectively control peri-implant mucositis, and adjunctive GPAP treatment seems to have a limited beneficial effect as compared with mechanical debridement alone. However, further clinical trials with a large sample size are needed to confirm this preliminary observation.

Secretory products of Escherichia coli biofilm modulate Candida biofilm formation and hyphal development.

AIM: To investigate the time- and concentration-dependent effects of Escherichia coli biofilm supernatant on Candida biofilm development, and to assess the effect of E. coli supernatant on Candida albicans hypha-specific genes (HSGs) expression. METHODS: The effect of E. coli biofilm supernatant on six Candida spp. was assessed by tetrazolium salt (XTT) reduction assay, scanning electron microscopy (SEM), and confocal laser scanning microscopy (CLSM). The effect of biofilm supernatant on the expression of C. albicans HSGs (ECE1, HWP1, HYR1, RBT1, RBT4, ALS3, and ALS8) and transcription factors (CPH1, CPH2, EFG1, TEC1, RAS1, TUP1, NRG1 and RFG1) was evaluated with real-time polymerase chain reaction (PCR). RESULTS: Escherichia coli biofilm secretory products significantly inhibited C. albicans, C. glabrata, C. tropicalis and C. krusei biofilms at 24 h and all Candida spp. at 48 h (P < 0.05), and SEM and CLSM confirmed these data. HSGs RBT1 and RBT4 were mostly up-regulated and ECE1, HWP1 and HYR1 were mostly down-regulated. ALS3 was totally suppressed. All HSGs were down-regulated at 48 h (P < 0.05). NRG1, RFG1 and EFG1, CPH1 and TEC1, and TUP1 and CPH2 showed similar expression trends and all were down-regulated at 48 h (P < 0.05). CONCLUSIONS: Escherichia coli secretory elements significantly impair Candida biofilm development possibly by modulating HSGs and its transcriptional regulation.

Self-reporting of periodontal diseases and clinical assessment outcome in a Swedish urban population of smokers and non-smokers.

The aim of this study was to determine whether there is an association between self-reporting of periodontal diseases and outcome in a clinical examination, and whether any difference is present in awareness of periodontal status between smokers and non-smokers. Participants comprised 1676 adults (838 M and 838 F aged between 31 and 40 years), 564 of whom reported being smokers. Subjects were asked via questionnaire whether they thought they had periodontal disease and why. A total of 1655 subjects answered the questionnaire and were subsequently divided into those who suspected having periodontal disease (Yes-group) and those who did not (No-group). A full-mouth clinical examination was carried out in all subjects. Female smokers in the Yes-group had a significantly higher number of teeth with pockets > or = 5 mm (P < 0.001) and a higher calculus index (CI-S, P < 0.01) than female smokers in the No-group. Male smokers in the Yes-group had significantly less remaining teeth (P < 0.01), more teeth with pockets > or = 5 mm (P < 0.001), and a higher CI-S (P < 0.05) than their counterparts in the No-group. For smokers, multivariate logistic regression analysis yielded an odds ratio (OR 3.21 [95% CI 1.73 5.74]) of self-reported periodontal disease to periodontitis outcome which was significant (P < 0.001). This association remained significant (P < 0.01) after adjustment for confounding factors. Subjects who reported having periodontal disease, especially those who also reported having movable teeth, were confirmed to have the disease. Smokers were more aware of their periodontal status than non-smokers.

[Effects of baicalin on the expression of pro-MMP-1 and MMP-3 in human gingival fibroblasts and periodontal ligament cells].

OBJECTIVE: To investigate the influence of baicalin on the IL-1beta induced pro-MMP-1 in HGF and the effects of baicalin on MMP-3 expression in periodontal ligament cells (PDLCs). METHODS: The amount of secreted pro-MMP-1 and MMP-3 expression was detected by ELISA and cell immunochemistry. RESULTS: (1) The amount of secreted pro-MMP-1 (3.333 +/- 0.123) microg/L increased significantly following 1 microg/L of IL-1beta, compared with control group (1.960 +/- 0.180) microg/L. Addition of baicalin to cell culture medium for 1 hour following IL-1beta decreased pro-MMP-1 secretion in a dose-dependent manner in the range of 10 approximately 1,000 microg/L. (2) 1 microg/L IL-1beta could significantly stimulate the synthesis and secretion of MMP-3 in PDLCs. (3) The baicalin could not interfere the synthesis of MMP-3, but could inhibit the release of MMP-3 from PDLCs. CONCLUSIONS: Baicalin could inhibit the secretion of pro-MMP-1 and MMP-3 expression in IL-1beta induced HGF and PDLCs, which suggests that baicalin may play an important role in preventing and treating periodontal disease.

[Observations of the non-surgical treatment response on diabetic patients with chronic periodontitis].

PURPOSE: To observe the non-surgical treatment response on diabetic patients with chronic periodontitis. METHODS: Moderate to advanced chronic periodontitis was studied in 36 Diabetes Mellitus (DM) patients classified as 20 cases with high and fluctuating blood glucose level (DM-H) and 16 cases with relatively low and stable blood glucose level (DM-L). 28 non-DM patients with chronic periodontitis served as control (Non-DM). Plaque Index (PlI), Gingival Index (GI), Bleeding on Probing (BOP), Probing Depth (PD) and Clinical Attachment Loss (AL) of all patients were recorded at 6 sites on each tooth at the baseline and in the first, the third, the sixth month after oral hygiene instrument (OHI), scaling and root planing. RESULTS: It was found that the short-term effect of non-surgical periodontal procedure had resulted in significant resolution of gingival inflammation and pronounced reduction in pocket depth and gain of attachment loss in all patients. The treatment response was similar in both DM and Non-DM patients with chronic periodontitis. CONCLUSIONS: Non-surgical periodontal treatment allowed for favorable treatment responses in a group of diabetic patients with chronic periodontitis and that their various profiles of blood glucose did not influence the short-term healing response to the treatment.