The role of NLRP3 in regulating gingival epithelial cell responses evoked by Aggregatibacter actinomycetemcomitans.

Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) has myriads of virulence factors among which leukotoxin provides A. actinomycetemcomitans with the advantage to thrive in the surrounding hostile environment and evade host immune defences. The NLRP3 inflammasome has been associated with periodontal disease development. However, our understanding of the involvement of caspase-1, caspase-4, and NLRP3 in the release of IL-1ß and other inflammatory mediators from gingival epithelial cells during a A. actinomycetemcomitans infection is limited. The aim of this study was to investigate how the inflammasome-associated proteins caspase-1, caspase-4 and NLRP3 regulate the immune response of gingival epithelial cells during a A. actinomycetemcomitans infection. Human gingival epithelial cells (Ca9-22) deficient in NLRP3, caspase-1 or caspase-4 were created using CRISPR/Cas9. Gingival epithelial cells were stimulated with the A. actinomycetemcomitans low-leukotoxic strain NCTC9710 or the highly leukotoxic JP2 strain HK 165 for 6, 12 and 24 h. The results showed that the JP2 strain HK1651 induced higher IL-1ß and IL-1RA release and mediated more epithelial cell death compared to the NCTC9710 strain. These findings were found to be capsase-1, caspase-4 and NLRP3-dependant. A targeted protein analysis of inflammation-related proteins showed that the expression of 37 proteins were identified as being significantly altered after HK1651 infection compared to unstimulated Cas9 and NLRP3-deficient cells. Of the 37 proteins, 23 of these inflammation-related proteins released by NLRP3-deficient cells differed significantly compared to Cas9 cells after infection. This suggests that NLRP3 has a broad effect on the inflammatory response in gingival epithelial cells.

Advanced Dental Cleaning is Associated with Reduced Risk of COPD Exacerbations - A Randomized Controlled Trial.

PURPOSE: Infections from the oral microbiome may lead to exacerbations of chronic obstructive pulmonary disease (COPD). We investigated whether advanced dental cleaning could reduce exacerbation frequency. Secondary outcomes were disease-specific health status, lung function, and whether the bacterial load and composition of plaque microbiome at baseline were associated with a difference in outcomes. PATIENTS AND METHODS: One-hundred-one primary and secondary care patients with COPD were randomized to intervention with advanced dental cleaning or to dental examination only, repeated after six months. At baseline and at 12 months, data of exacerbations, lung function, COPD Assessment Test (CAT) score, and periodontal status were collected from questionnaires, record review, and periodontal examination. Student's t-test and Mann-Whitney-U (MWU) test compared changes in outcomes. The primary outcome variable was also assessed using multivariable linear regression with adjustment for potential confounders. Microbiome analyses of plaque samples taken at baseline were performed using Wilcoxon signed ranks tests for calculation of alpha diversity, per mutational multivariate analysis of variance for beta diversity, and receiver operating characteristic curves for prediction of outcomes based on machine learning models. RESULTS: In the MWU test, the annual exacerbation frequency was significantly reduced in patients previously experiencing frequent exacerbations (p = 0.020) and in those with repeated advanced dental cleaning (p = 0.039) compared with the non-treated control group, but not in the total population including both patients with a single and repeated visits (p = 0.207). The result was confirmed in multivariable linear regression, where the risk of new exacerbations was significantly lower in patients both in the intention to treat analysis (regression coefficient 0.36 (95% CI 0.25-0.52), p < 0.0001) and in the population with repeated dental cleaning (0.16 (0.10-0.27), p < 0.0001). The composition of microbiome at baseline was moderately predictive of an increased risk of worsened health status at 12 months (AUC = 0.723). CONCLUSION: Advanced dental cleaning is associated with a reduced frequency of COPD exacerbations. Regular periodontal examination and dental cleaning may be of clinical importance to prevent COPD exacerbations.