Gingival crevicular fluid periodontal ligament-associated protein-1, sclerostin, and tumor necrosis factor-alpha levels in periodontitis.

BACKGROUND: In periodontitis, the equilibrium between bone formation and resorption skews in favor of bone loss. Periodontal ligament-associated protein-1 (PLAP-1) and sclerostin play a significant role in the suppression of bone formation. Tumor necrosis factor-alpha (TNF-α) is a central proinflammatory cytokine related to periodontal bone loss. This study aims to assess gingival crevicular fluid (GCF) PLAP-1, sclerostin, and TNF-α levels in individuals with periodontal disease. METHODS: Seventy-one individuals diagnosed with generalized stage III grade C periodontitis (n = 23), gingivitis (n = 24), and periodontal health (n = 24) were included in the study. Full-mouth clinical periodontal measurements were performed. PLAP-1, sclerostin, and TNF-α total amounts in GCF were quantified by ELISA. Nonparametric methods were used for the data analyses. RESULTS: Periodontitis group exhibited significantly higher GCF PLAP-1, sclerostin and TNF-α levels compared with gingivitis and periodontally healthy groups (p < 0.05). GCF PLAP-1 and TNF-α levels of gingivitis group were higher than healthy controls (p < 0.05) whereas GCF sclerostin levels were similar in two groups (p > 0.05). Significant positive correlations were found between GCF PLAP-1, sclerostin and TNF-α levels and all clinical parameters (p < 0.01). CONCLUSIONS: To our knowledge, this is the first study showing GCF PLAP-1 levels in periodontal health and disease. Increased GCF PLAP-1 and sclerostin levels and their correlations with TNF-α in periodontitis imply that those molecules might be involved in the pathogenesis of periodontal disease. Further studies in larger mixed cohorts are needed to enlighten the possible role of PLAP-1 and sclerostin in periodontal bone loss.

Six miRNA expressions in the saliva of smokers and non-smokers with periodontal disease.

BACKGROUND: It has been stated that microRNA (miRNA) plays an important role in development, homeostasis, and immune functions, and abnormal miRNA expression may cause faster disease progression. OBJECTIVE: The aim of this study was to determine miR-203, miR-142-3p, miR-146a, miR-146b, miR-155, and miR-29b gene expressions in the saliva of smokers and non-smokers with the periodontal disease before and after non-surgical periodontal therapy (NSPT). METHODS: A total of 90 individuals, 30 with periodontitis, 30 with gingivitis, and 30 periodontally healthy (control group), were included. These three groups were divided into subgroups as smoking and non-smoking individuals, with 15 people in each group. NSPT was applied to patients with periodontitis and gingivitis. Saliva samples and clinical parameters were obtained at baseline and repeated 6 weeks after NSPT. RESULTS: Saliva miR-203, miR-142-3p, miR-146a, miR-146b, and miR-155 gene expressions were significantly upregulated in patients with periodontal disease compared to the control group both in smokers and non-smokers, and also these miRNAs' gene expressions were significantly higher in the periodontitis group than in the gingivitis group at baseline (p < .05). A significant increase in saliva miR-142-3p expression was detected in all groups of smokers compared to non-smokers (p < .05). Although there was a decrease in salivary miRNAs gene expressions with the treatment, it was not statistically significant (p > .05). CONCLUSIONS: These results suggest that salivary miR-146a, miR-146b, miR142-3p, miR-155, and miR-203 gene expressions increased with the progression of periodontal disease, but unchanged after periodontal treatment. Moreover, smoking may contribute to an increase in the levels of salivary miR-142-3p in the periodontal health and disease.

Association of the CD14 -260C/T polymorphism with plaque-induced gingivitis depends on the presence of Porphyromonas gingivalis.

BACKGROUND: Plaque-induced gingivitis is the most prevalent periodontal disease associated with pathogenic biofilms. The host immune system responds to pathogens through pattern recognition receptors (PRRs), such as Toll-like receptors (TLRs) and their co-receptor cluster of differentiation 14 (CD14). AIM: This study investigated the association between the functional polymorphism in the CD14 gene and the dental plaque microbiota in children with gingivitis. DESIGN: A total of 590 unrelated children (307 with plaque-induced gingivitis and 283 controls, aged 13-15 years) were enrolled in this case-control study. Dental plaque was processed using a ParoCheck® 20 detection kit. The CD14 -260C/T (rs2569190) polymorphism was determined with the PCR-RFLP method. RESULTS: Gingivitis was detected in 64.2% of boys and 35.8% of girls (P < .001). Children with gingivitis had a significantly higher occurrence of dental caries (P < .001). No significant differences in the CD14 -260C/T allele and genotype distribution among individuals with or without gingivitis in the whole cohort were found. Children with gingivitis and P gingivalis, however, were significantly more frequent carriers of the CT and TT genotypes than children with gingivitis without P gingivalis or healthy controls (P < .05). CONCLUSIONS: The CD14 -260C/T polymorphism acts in cooperation with P gingivalis to trigger plaque-induced gingivitis in Czech children.

Identification of Streptococcus sanguinis genes producing biofilm from gingivitis.

Streptococcus sanguinis is a teeth commensal frontier colonizer and among the most common species in the oral biofilm. Dental plaque, caries, and gingivitis/periodontitis are caused by dysbiosis of oral flora. A biofilm assay was developed to investigate biofilm formation in S. sanguinis using the microtiter plate, tube, and Congo red agar methods in order to identify causing bacteria and determine responsible genes. Three genes, including pur B, thr B, and pyre E, were suspected of playing a role in forming in vivo biofilms in S. sanguinis. The present study shows these genes to be responsible for increased biofilm formation in gingivitis patients.

Association between Epstein-Barr virus and periodontitis: A meta-analysis.

PURPOSE: Previous studies have found that Epstein-Barr virus (EBV) is associated with periodontitis, though some controversy remains. This meta-analysis aimed to clarify and update the relationship between EBV and periodontitis as well as clinical parameters. METHODS: A comprehensive search was conducted in the PubMed and Scopus databases in December 2020. Original data were extracted according to defined inclusion and exclusion criteria. Outcomes were analyzed, including overall odds ratios (ORs) and 95% confidence intervals (CIs). A random-effects model was used, and publication bias was assessed by Egger's and Begg's tests. Sensitivity analysis was used to evaluate the stability of the outcome. RESULTS: Twenty-six studies were included in the present meta-analysis, involving 1354 periodontitis patients and 819 healthy controls. The included studies mostly showed high quality. The overall quantitative synthesis for the association between EBV and periodontitis was an increased odds ratio when subgingival EBV was detected OR = 7.069, 95% CI = 4.197-11.905, P<0.001). The results of subgroup analysis suggested that the association of EBV with periodontitis was significant in Asian, European, and American populations (P<0.001; P = 0.04; P = 0.003, respectively) but not in African populations (P = 0.29). Subgroup analysis by sample type showed that subgingival plaque (SgP), tissue and gingival crevicular fluid GCF were useful for EBV detection (P<0.001). EBV detection amplification methods included nested PCR, multiplex PCR and PCR (P<0.001; P = 0.05, P<0.001, respectively), but EBV detection by real-time PCR and loop-mediated isothermal amplification presented no significant result (P = 0.06; P = 0.3, respectively). For the clinical parameters of periodontitis, pocket depth (PD) and bleeding of probing (BOP) percentages were higher in the EBV-positive sites than in the EBV-negative sites (MD 0.47 [0.08, 0.85], P = 0.02; MD 19.45 [4.47, 34.43], P = 0.01). CONCLUSIONS: A high frequency of EBV detection is associated with an increased risk of periodontitis. The EBV association was particularly significant in all populations except in African populations. Subgigival plaque (SgP), tissue and GCF were not significantly different useful material for detecting EBV in periodontitis. Nested PCR and multiplex PCR are reliable methods for this purpose. In the presence of EBV, PD and BOP are reliable clinical parameters for gingival inflammation. However, some caution in such interpretation is justified due to heterogeneity among studies. A suggested extension could assess the parallel influence of other human herpesviruses.

Differential DNA methylation and mRNA transcription in gingival tissues in periodontal health and disease.

AIM: We investigated differential DNA methylation in gingival tissues in periodontal health, gingivitis, and periodontitis, and its association with differential mRNA expression. MATERIALS AND METHODS: Gingival tissues were harvested from individuals and sites with clinically healthy and intact periodontium, gingivitis, and periodontitis. Samples were processed for differential DNA methylation and mRNA expression using the IlluminaEPIC (850 K) and the IlluminaHiSeq2000 platforms, respectively. Across the three phenotypes, we identified differentially methylated CpG sites and regions, differentially expressed genes (DEGs), and genes with concomitant differential methylation at their promoters and expression were identified. The findings were validated using our earlier databases using HG-U133Plus2.0Affymetrix microarrays and Illumina (450 K) methylation arrays. RESULTS: We observed 43,631 differentially methylated positions (DMPs) between periodontitis and health, and 536 DMPs between gingivitis and health (FDR < 0.05). On the mRNA level, statistically significant DEGs were observed only between periodontitis and health (n = 126). Twelve DEGs between periodontitis and health (DCC, KCNA3, KCNA2, RIMS2, HOXB7, PNOC, IRX1, JSRP1, TBX1, OPCML, CECR1, SCN4B) were also differentially methylated between the two phenotypes. Spearman correlations between methylation and expression in the EPIC/mRNAseq dataset were largely replicated in the 450 K/Affymetrix datasets. CONCLUSIONS: Concomitant study of DNA methylation and gene expression patterns may identify genes whose expression is epigenetically regulated in periodontitis.

Tumour necrosis factor-alpha polymorphism -308 G/a and its protein in subjects with gingivitis.

OBJECTIVE: This study examined the association between tumour necrosis factor-alpha (TNF- α) (-308 G/A) polymorphism and gingivitis, and serum and salivary TNF- α levels, in a Mexican population. MATERIAL AND METHODS: This study enrolled 171 subjects, divided into two groups: healthy subjects and gingivitis patients. TNF- α (-308 G/A) gene polymorphism was analyzed by PCR-RFLP assay. Salivary and serum samples were used to measure cytokine levels through the ELISA technique. RESULTS: TNF- α (-308 G/A) polymorphism was shown to have a protective effect in carriers of the A/A genotype and allele A. The G/A genotype is associated with an increase in high-density lipoprotein cholesterol (HDL-C) levels in the gingivitis group. Healthy individuals had higher levels of salivary TNF- α and HDL-C, and increased salivary flow. Triglycerides, low-density lipoprotein cholesterol, and very low-density lipoprotein cholesterol levels were increased in the gingivitis group. No statistical differences were found in serum TNF- α levels. CONCLUSION: Our data demonstrate that the TNF- α -308 A/A genotype exerts a protective effect against gingivitis. Moreover, oral conditions are associated with some biochemical parameters.

Genetic polymorphisms in interleukin-6 and interleukin-1-beta were associated with dental caries and gingivitis.

OBJECTIVE: Evaluate the association between single nucleotide polymorphisms (SNPs) in Interleukin-6 (IL-6) gene (rs1800795) and in Interleukin-1-beta (IL-1ß) gene (rs1143627 and rs1143629) with dental caries and gingivitis in Brazilian children. MATERIAL AND METHODS: Three hundred and fifty-three children aged 8-11 years were included. Visible biofilm and gingival bleeding were evaluated by Community Periodontal Index. The International System for Detection and Assessment of Carious Lesions (ICDAS) was used to investigate dental caries. Real-time PCR evaluated SNPs in the DNA. Chi-square test, haplotype analysis and logistic regression were applied (alpha of 5%). RESULTS: The GG genotype in rs1800795 (IL-6) decreases the risk of gingivitis in a co-dominant model (p = .05; OR = 0.64). The GG genotype in rs1143627 (IL-1ß) reduces the risk of dental caries (Co-dominant model: ICDAS0 versus ICDAS1-6: p = .05; OR = 0.55. ICDAS0-2 versus ICDAS3-6: p = .02; OR = 0.49. Recessive model: ICDAS0 versus ICDAS1-6: p = .005; OR = 0.48. ICDAS0-2 versus ICDAS3-6: p = .004; OR = 0.45. Logistic regression: ICDAS0-2 versus ICDAS3-6: p = .05; OR = 0.24; CI 95%= 0.05-1.00). The GG genotype in rs1143629 was more frequent in ICDAS0 (p = .05; OR: 0.60). In the haplotype analysis, IL-1ß was associated with gingivitis. CONCLUSION: The rs1800795 in IL-6 gene was associated with gingivitis. The rs1143627 and rs1143629 in IL-1ß were associated with dental caries and gingivitis.

Detection of Salivary Small Extracellular Vesicles Associated Inflammatory Cytokines Gene Methylation in Gingivitis.

Salivary small extracellular vesicles (sEV) are emerging as a potential liquid biopsy for oral diseases. However, technical difficulties for salivary sEV isolation remain a challenge. Twelve participants (five periodontally healthy, seven gingivitis patients) were recruited and salivary sEV were isolated by ultracentrifuge (UC-sEV) and size exclusion chromatography (SEC-sEV). The effect of UC and SEC on sEV yield, DNA methylation of five cytokine gene promoters (interleukin (IL)-6, tumor necrosis factor (TNF)-α, IL-1ß, IL-8, and IL-10), and functional uptake by human primary gingival fibroblasts (hGFs) was investigated. The results demonstrated that SEC-sEV had a higher yield of particles and particle/protein ratios compared to UC-sEV, with a minimal effect on the detection of DNA methylation of five cytokine genes and functional uptake in hGFs (n = 3). Comparing salivary sEV characteristics between gingivitis and healthy patients, gingivitis-UC-sEV were increased compared to the healthy group; while no differences were found in sEV size, oral bacterial gDNA, and DNA methylation for five cytokine gene promoters, for both UC-sEV and SEC-sEV. Overall, the data indicate that SEC results in a higher yield of salivary sEV, with no significant differences in sEV DNA epigenetics, compared to UC.

Salivary Small Extracellular Vesicles Associated miRNAs in Periodontal Status-A Pilot Study.

This pilot study aims to investigate whether salivary small extracellular vesicle (sEV)-associated microRNAs could act as potential biomarkers for periodontal disease status. Twenty-nine participants (10 who were healthy, nine with gingivitis, 10 with stage III/IV periodontitis) were recruited and unstimulated whole saliva samples were collected. Salivary sEVs were isolated using the size-exclusion chromatography (SEC) method and characterised by morphology, EV-protein and size distribution using transmission electron microscopy (TEM), Western Blot and Nanoparticle Tracking Analysis (NTA), respectively. Ten mature microRNAs (miRNAs) in salivary sEVs and saliva were evaluated using RT-qPCR. The discriminatory power of miRNAs as biomarkers in gingivitis and periodontitis versus healthy controls was evaluated by Receiver Operating Characteristics (ROC) curves. Salivary sEVs were comparable to sEVs morphology, mode, size distribution and particle concentration in healthy, gingivitis and periodontitis patients. Compared to miRNAs in whole saliva, three significantly increased miRNAs (hsa-miR-140-5p, hsa-miR-146a-5p and hsa-miR-628-5p) were only detected in sEVs in periodontitis when compared to that of healthy controls, with a good discriminatory power (area under the curve (AUC) = 0.96) for periodontitis diagnosis. Our study demonstrated that salivary sEVs are a non-invasive source of miRNAs for periodontitis diagnosis. Three miRNAs that are selectively enriched in sEVs, but not whole saliva, could be potential biomarkers for periodontal disease status.

Tracking the functional meaning of the human oral-microbiome protein-protein interactions.

The interactome - the network of protein-protein interactions (PPIs) within a cell or organism - is technically difficult to assess. Bioinformatic tools can, not only, identify potential PPIs that can be later experimentally validated, but also be used to assign functional meaning to PPIs. Saliva's potential as a non-invasive diagnostic fluid is currently being explored by several research groups. But, in order to fully attain its potential, it is necessary to achieve the full characterization of the mechanisms that take place within this ecosystem. The onset of omics technologies, and specifically of proteomics, delivered a huge set of data that is largely underexplored. Quantitative information relative to proteins within a given context (for example a given disease) can be used by computational algorithms to generate information regarding PPIs. These PPIs can be further analyzed concerning their functional meaning and used to identify potential biomarkers, therapeutic targets, defense and pathogenicity mechanisms. We describe a computational pipeline that can be used to identify and analyze PPIs between human and microbial proteins. The pipeline was tested within the scenario of human PPIs of systemic (Zika Virus infection) and of oral conditions (Periodontal disease) and also in the context of microbial interactions (Candida-Streptococcus) and showed to successfully predict functionally relevant PPIs. The pipeline can be applied to different scientific areas, such as pharmacological research, since a functional meaningful PPI network can provide insights on potential drug targets, and even new uses for existing drugs on the market.

Interplay Between the Host, the Human Microbiome, and Drug Metabolism.

The human microbiome is composed of four major areas including intestinal, skin, vaginal, and oral microbiomes, with each area containing unique species and unique functionalities. The human microbiome may be modulated with prebiotics, probiotics, and postbiotics to potentially aid in the treatment of diseases like irritable bowel syndrome, bacterial vaginosis, atopic dermatitis, gingivitis, obesity, or cancer. There is also potential for many of the inhabitants of the human microbiome to directly modulate host gene expression and modulate host detoxifying enzyme activity like cytochrome P450s (CYPs), dehydrogenases, and carboxylesterases. Therefore, the microbiome may be important to consider during drug discovery, risk assessment, and dosing regimens for various diseases given that the human microbiome has been shown to impact host detoxification processes.

What Is the Heritability of Periodontitis? A Systematic Review.

The aim of this study was to systematically appraise the existing literature on the yet-unclear heritability of gingivitis and periodontitis. This review was conducted following the PRISMA guidelines. A search was conducted through the electronic databases Medline, Embase, LILACS, Cochrane Library, Open Grey, Google Scholar, and Research Gate, as complemented by a hand search, for human studies reporting measures of heritability of gingivitis and periodontitis. A total of 9,037 papers were initially identified from combined databases and 10,810 on Google Scholar. After full-text reading, 28 articles met the inclusion criteria and were carried forward to data abstraction. The reviewed data included information from >50,000 human subjects. Meta-analyses were performed by grouping studies based on design and outcome. Heritability ( H2) of periodontitis was estimated at 0.38 (95% CI, 0.34 to 0.43; I2 = 12.9%) in twin studies, 0.15 (95% CI, 0.06 to 0.24; I2 = 0%) in other family studies, and 0.29 (95% CI, 0.21 to 0.38; I2 = 61.2%) when twin and other family studies were combined. Genome-wide association studies detected a lower heritability estimate of 0.07 (95% CI, -0.02 to 0.15) for combined definitions of periodontitis, increasing with disease severity and when the interaction with smoking was included. Furthermore, heritability tended to be lower among older age groups. Heritability for the self-reported gingivitis trait was estimated at 0.29 (95% CI, 0.22 to 0.36; I2 = 37.6%), while it was not statistically significant for clinically measured gingivitis. This systematic review brings forward summary evidence to confirm that up to a third of the periodontitis variance in the population is due to genetic factors. This seems consistent across the different studied populations and increases with disease severity. In summary, up to a third of the variance of periodontitis in the population is due to genetic factors, with higher heritability for more severe disease.

ANALYSIS OF LOCAL IMMUNITY INDICATORS OF THE ORAL CAVITY AND DEGREE OF GINGIVITIS DEPENDING ON MUTATION OF CFTR GENE IN CHILDREN WITH CYSTIC FIBROSIS.

The aim of the work was to establish the relationship between the genotype of the cystic fibrosis transmembrane conductance regulator (CFTR), the level of local immune reactivity and the degree of chronic gingivitis in children with cystic fibrosis. The study has shown significant differences in the local immunity indices of the oral mucosa and the condition of periodontal tissues in children with cystic fibrosis in comparison with the control group. The features of the course of dental pathology among sick children, depending on the type of CFTR gene mutation are determined. Disturbance of mucosal immunity of the oral cavity in children with cystic fibrosis is manifested by a decrease in lysozyme activity in mixed saliva by 1.5 times and level of secretory immunoglobulins IgA by 1.4 times. A consequence of this is an increase of the degree of dysbiosis of the oral cavity by 3.7 times. At the same time, a lesser imbalance in the microflora and lysozyme activity observed in the homozygote group of the F508del mutation, and heterozygotes of the F508del mutation have the most severe manifestations of chronic gingivitis.

Keratinocyte-specific ablation of protease-activated receptor 2 prevents gingival inflammation and bone loss in a mouse model of periodontal disease.

Chronic periodontitis is characterised by gingival inflammation and alveolar bone loss. A major aetiological agent is Porphyromonas gingivalis, which secretes proteases that activate protease-activated receptor 2 (PAR2 ). PAR2 expressed on oral keratinocytes is activated by proteases released by P. gingivalis, inducing secretion of interleukin 6 (IL-6), and global knockout of PAR2 prevents bone loss and inflammation in a periodontal disease model in mice. To test the hypothesis that PAR2 expressed on gingival keratinocytes is required for periodontal disease pathology, keratinocyte-specific PAR2 -null mice were generated using K14-Cre targeted deletion of the PAR2 gene (F2rl1). These mice were subjected to a model of periodontitis involving placement of a ligature around a tooth, combined with P. gingivalis infection ("Lig + Inf"). The intervention caused a significant 44% decrease in alveolar bone volume (assessed by microcomputed tomography) in wildtype (K14-Cre:F2rl1wt/wt ), but not littermate keratinocyte-specific PAR2 -null (K14-Cre:F2rl1fl/fl ) mice. Keratinocyte-specific ablation of PAR2 prevented the significant Lig + Inf-induced increase (2.8-fold) in the number of osteoclasts in alveolar bone and the significant up-regulation (2.4-4-fold) of the inflammatory markers IL-6, IL-1ß, interferon-γ, myeloperoxidase, and CD11b in gingival tissue. These data suggest that PAR2 expressed on oral epithelial cells is a critical regulator of periodontitis-induced bone loss and will help in designing novel therapies with which to treat the disease.

An Analytical Method for Assessing Optimal Storage Conditions of Gingival Crevicular Fluid and Disclosing a Peptide Biomarker Signature of Gingivitis by MALDI-TOF MS.

PURPOSE: Gingival crevicular fluid (GCF) is an important diagnostic source of biomarkers for both periodontitis and gingivitis. However, GCF peptide signature may change depending on factors such as handling and storage. Here we propose a standardized methodology for GCF analysis by MALDI-TOF/TOF-MS in order to distinguish a characteristic peptide signature of gingivitis. EXPERIMENTAL DESIGN: The best storage/handling conditions which may ensure the stability of the endogenous peptidome in GCF is determined and then MALDI-TOF MS comparative analysis is performed. Reproducible GCF MALDI-TOF signatures between two groups of gingivitis (n = 10) and healthy (n = 10) subjects are compared. RESULTS: A pattern of five peptides resulted differentially expressed between gingivitis and healthy groups. Interestingly, among these biomarkers the C-terminal fragment of alpha-1-antitrypsin (AAT) namely C-36 peptide and two different PTMs of the full-length S100A9 protein are found. CONCLUSIONS AND CLINICAL RELEVANCE: The method described provides a rapid comparative analysis of GCF signatures between periodontally healthy and gingivitis subjects. A pattern based on the expression of endogenous peptides and their PTMs is identified in GCF as putative biomarkers of gingivitis. These findings improve the knowledge of the inflammatory, immune, and structural substrates which might have a key role in the pathogenesis of gingivitis.

Prevalence of Periodontal Destruction and Putative Periodontal Pathogens in the Same Lebanese Family.

AIM: Periodontal diseases are associated with microorganisms rich in Gram-negative species. Several studies have indicated the presence of few a periodontopathic microorganisms in the same family. A parent with severe adult periodontitis, who is infected with bacteria associated with periodontal disease, may function as a source of infection. Their children may be at a greater risk to become colonized with bacteria. The purpose of this investigation was (1) to explore the presence of three bacteria, such as Porphyromonas gingivalis (PG), Prevotella intermedia (PI), and Aggregatibacter actinomycetemcomitans (AA) in the same Lebanese family and (2) to study the clinical destruction in the same family and their relations as members of this family due to the presence of PG. MATERIALS AND METHODS: A total of 10 families were screened; only 5 (13 females and 5 males) were selected for this study, and at least one member of the family had untreated periodontal disease, chronic or aggressive. Every participant signed an informed consent form. A total of 18 available deoxyribonucleic acid (DNA) samples were taken to analyze the presence of three periodontal bacteria. STATISTICS: Multiple logistic regression was used for the exact methods. RESULTS: All 18 patients showed a positive result for PI. Also, PG. was recognized in 15 patients while AA was not detected in any of the subjects. All couples suffered from periodontitis, chronic or aggressive forms, five children suffered from gingivitis, three children had no clinical manifestation, and only one suffered from localized aggressive periodontitis. The statistical analysis showed with each 1 year of increase in age, the odds of having periodontal disease multiply by 1.39, i.e., age as a risk factor for periodontal disease due to the presence of PG and sharing the same plate. CONCLUSION: This investigation demonstrates a high prevalence of periodontal microorganisms in children and young adults of Lebanese periodontitis parents and a microbiological similarity between the children and their mothers. All these factors could be a high risk of developing periodontal disease in the future. CLINICAL SIGNIFICANCE: This article shows that vertical transmission of microorganisms is a possible risk factor for developing periodontal disease in the offspring.

Structural insights unravel the zymogenic mechanism of the virulence factor gingipain K from Porphyromonas gingivalis, a causative agent of gum disease from the human oral microbiome.

Skewing of the human oral microbiome causes dysbiosis and preponderance of bacteria such as Porphyromonas gingivalis, the main etiological agent of periodontitis. P. gingivalis secretes proteolytic gingipains (Kgp and RgpA/B) as zymogens inhibited by a pro-domain that is removed during extracellular activation. Unraveling the molecular mechanism of Kgp zymogenicity is essential to design inhibitors blocking its activity. Here, we found that the isolated 209-residue Kgp pro-domain is a boomerang-shaped all-ß protein similar to the RgpB pro-domain. Using composite structural information of Kgp and RgpB, we derived a plausible homology model and mechanism of Kgp-regulating zymogenicity. Accordingly, the pro-domain would laterally attach to the catalytic moiety in Kgp and block the active site through an exposed inhibitory loop. This loop features a lysine (Lys129) likely occupying the S1 specificity pocket and exerting latency. Lys129 mutation to glutamate or arginine led to misfolded protein that was degraded in vivo Mutation to alanine gave milder effects but still strongly diminished proteolytic activity, without affecting the subcellular location of the enzyme. Accordingly, the interactions of Lys129 within the S1 pocket are also essential for correct folding. Uniquely for gingipains, the isolated Kgp pro-domain dimerized through an interface, which partially overlapped with that between the catalytic moiety and the pro-domain within the zymogen, i.e. both complexes are mutually exclusive. Thus, pro-domain dimerization, together with partial rearrangement of the active site upon activation, explains the lack of inhibition of the pro-domain in trans. Our results reveal that the specific latency mechanism of Kgp differs from those of Rgps.

Vitamin D Receptor TaqI Gene Polymorphism and Dental Caries in Czech Children.

AIM: We analyzed the VDR TaqI (rs731236) gene polymorphism in children with and those without dental caries. METHODS: A total of 388 subjects, 153 caries-free (with decayed/missing/filled teeth [DMFT] = 0) and 235 children with dental caries (DMFT ≥1), were genotyped by the TaqMan method. RESULTS: Although no significant differences in VDR TaqI allele and genotype frequencies between caries-free and caries-affected children were detected, a significant association between this polymorphism and gingivitis was found (p < 0.05). CONCLUSIONS: In contrast to previous studies from China and Turkey, the VDR TaqI gene variant cannot be used as a marker for identification of Czech children with increased dental caries risk.

Unfolded protein response-related gene regulation in inflamed periodontal tissues with and without Russell bodies.

OBJECTIVE: To examine the expression of unfolded protein response (UPR) genes, a set of genes that are activated to assist in protein trafficking and cellular homeostasis when endoplasmic reticulum (ER) stress occurs, in inflamed and uninflamed periodontal tissues, with or without Russell bodies (RB). RB are a histologically apparent extension of the ER that represents an accumulation of abnormal proteins that cannot be secreted or degraded and may serve as a marker of ER stress. DESIGN: Periodontal tissue specimens were collected and categorised histologically based on the presence of inflammation and the quantity of RB. The differential regulation of 84 UPR-related genes was examined by qRT(2)-PCR. RESULTS: UPR genes related to the inositol-requiring ER-to-nucleus signal kinase (IRE)-1 pathway, molecular chaperones and ER quality control were up-regulated in RB(+) tissues compared with RB(-) tissues, irrespective of inflammation. Inflamed periodontal tissues showed a marked down-regulation of heat shock protein (HSP)-70 family members. CONCLUSION: The presence of RB in inflamed periodontal tissues correlated with the expression of a unique set of ER stress-related genes and therefore may serve as a marker of UPR response in periodontal inflammation. Inflamed periodontal tissues showed a marked down-regulation of UPR genes, in particular HSP70. This may be contributory to disease progression in periodontal disease.