Neonicotinoid pesticides are highly persistent in the environment, with detection in periodontal blood reported. Although an association with gingival inflammation has been shown, the mechanism related to periodontal disease remains unclear. Previous study found that coxsackievirus and adenovirus receptor (CXADR) is involved in gingival tissue epithelial barrier function, thus the effects of neonicotinoids on CXADR were examined. High performance liquid chromatography of salivary samples from 16 volunteers detected acetamiprid, clothianidin, imidacloprid, and thiamethoxam. Administration of neonicotinoids (Σneonicotinoids) resulted in loss of cell-surface CXADR, which was restored by bafilomycin A1, a lysosomal inhibitor. Using a three-dimensional tissue model of human gingival epithelial cells, Σneonicotinoids were found to increase permeability to lipopolysaccharide (LPS) and peptidoglycan (PGN), which was dependent on CXADR. It is thus suggested that neonicotinoids cause mislocalization of CXADR into lysosomes, leading to gingival barrier function disruption, which allows for bacterial virulence factors to penetrate subepithelial tissues.

Cohen syndrome is an autosomal recessive genetic disease caused by mutations in the vacuolar protein sorting homolog B (VPS13B) gene that leads to a variety of complications including periodontitis. However, the molecular mechanism underlying periodontal inflammation caused by VPS13B dysfunction in human gingival epithelial cells remains unclear. A previous report noted that coxsackievirus and adenovirus receptor (CXADR) and junctional adhesion molecule 1 (JAM1) are involved in barrier functions against penetration by lipopolysaccharide (LPS) and peptidoglycan (PGN) into gingival tissues. The present study was conducted to examine the effects and significance of VPS13B on gingival barrier function. It was confirmed that loss of VPS13B resulted in decreased cell surface localization of CXADR, but not of JAM1. Additionally, abundant lysosomal localization of CXADR was detected in VPS13B-knockout cells followed treatment with bafilomycin A1, an inhibitor of lysosomal degradation. Other findings indicated that cell-surface localization of the CXADR-chimeric protein, in which C-terminus was exchanged with JAM1, was not disturbed by VPS13B knockout. Finally, VPS13B knockout led to greater permeability of gingival epithelial cell layers and tissues to LPS and PGN, which was restored by increased expression of CXADR-JAM1c-term. Together, these results show that VPS13B is involved in intracellular trafficking of CXADR as well as the barrier function of human gingival epithelial tissues, and thus indicate the molecular basis for periodontal complications in patients affected by Cohen syndrome.

AIMS/INTRODUCTION:Diabetes and periodontal disease, a bacterial infection involving the oral microbiome, have a bidirectional relationship. However, the relationship between poor glycemic control and the oral microbiome remains unclear. The aim of this study was to assess the direct effect of intensive glycemic control on the oral microbiome in patients with type 2 diabetes mellitus (T2DM). MATERIALS AND METHODS:Twenty-nine patients with T2DM and 29 controls were enrolled in this study. Patients underwent a 2-week intensive glycemic control regimen. We collected subgingival dental plaque and conducted full-length 16S ribosomal RNA gene sequencing to identify bacterial species. The focus was on the subgingival microbiome, particularly 29 species of oral bacteria related to periodontal disease, and the characteristics of the diabetic cohort. Periodontal inflammation was quantified using the periodontal inflamed surface area (PISA). RESULTS:Prior to diabetes treatment, the relative abundance of Porphyromonas gingivalis (P = 0.018), Tannerella forsythia (P < 0.001), Fusobacterium nucleatum (P = 0.041), and Prevotella intermedia (P < 0.001), known for their high pathogenicity in periodontal disease, was higher in the diabetes group than in the control group. The bacterial species whose relative abundance changed significantly before and after treatment differed between the PISA improved and non-improved groups in patients with diabetes. CONCLUSIONS:Oral bacteria changed pre- and post-diabetes treatment, correlating with improvements in PISA.

Dental caries, a dysbiotic biofilm disease driven by polymicrobial acidogenesis, often coexists with type 2 diabetes (T2D). Previous studies suggest covarying relationships between circulating and salivary metabolites in patients with T2D. However, the role of hyperglycemia-induced saccharide migration from plasma to saliva in caries pathogenesis remains unclear. Here, we developed a novel method for untargeted metabolomics profiling of trace saliva from sublingual and submandibular glands, comparing this profile with those of plasma and whole saliva in participants with T2D (n = 31) and those with normoglycemia (n = 30). This comparison aimed to determine how circulating saccharide migration into the oral cavity and its subsequent microbial consumption are linked to dental caries. Additionally, shotgun metagenomic sequencing was combined with this analysis to investigate the cariogenic impact of circulating saccharide migration on the composition and function of supragingival biofilm using MetaPhlAn4 and HUMAnN3 pipelines. The metabolomics profiles of glandular saliva showed intermediate dissimilarity between plasma and whole saliva, reflecting cardiometabolic traits more sensitively than whole saliva. Glucose and fructose showed a decreasing positive correlation with glycemic parameters in the order of plasma, glandular saliva, and whole saliva, suggesting systemic-to-oral migration and subsequent microbial consumption. Saccharide migration was more pronounced in participants with dental caries and plaque accumulation, coinciding with shifts in supragingival microbiota, including depletion of Streptococcus sanguinis, Corynebacterium durum, and Rothia aeria, and enrichment of Streptococcus mutans, Veillonella parvula, and Actinomyces sp. oral taxon 448. Glycolytic potential increased at the community level. Improved glycemic control reduced fructose migration and mitigated dysbiosis, decreasing fructose phosphotransferase abundance and shifting the S. mutans–S. sanguinis balance. Experimental validation demonstrated that fructose promotes S. mutans dominance over S. sanguinis in dual-species biofilms. This study establishes saccharide migration as a metabolic driver of supragingival dysbiosis in T2D. The findings highlight the role of both glucose and fructose in caries pathogenesis and suggest that glycemic control could serve as an effective strategy as part of caries control.

BackgroundKostmann syndrome is an autosomal recessive disorder caused by a mutation of the hematopoietic cell-specific Lyn substrate 1 associated protein X-1 (HAX1) gene, and characterized by low number of neutrophils and increased susceptibility to infections. Additionally, Kostmann syndrome is known to be complicated by periodontitis, though the etiological molecular basis remains unclear. We previously reported findings showing that junctional adhesion molecule 1 (JAM1), a tight junction-associated protein, has an important role to maintain epithelial barrier function in gingival tissues, which prevents penetration of bacterial virulence factors, such as lipopolysaccharide (LPS) and peptidoglycan (PGN). In the present study, the effects of HAX1 on gingival barrier function were investigated.ResultsExaminations of immortalized human gingival epithelial (IHGE) cells showed HAX1 localization in mitochondria. In HAX1-knockdown IHGE cells, significantly decreased levels of JAM1 were found. Additionally, cisplatin, a chemotherapeutic agent reported to inhibit HAX1, also led to decreased expression of both HAX1 and JAM1. Furthermore, JAM1 was scarcely detected in HAX1-knockout cells, while administration of bafilomycin A1, a lysosomal inhibitor, restored JAM1 expression in those cells. Finally, using a three-dimensional multilayered gingival epithelial tissue model, HAX1 knockout along with cisplatin administration was also found to increase permeability to LPS and PGN, which was dependent on JAM1 expression.ConclusionThese results indicate that periodontal diseases complicated with Kostmann syndrome are induced by reduced JAM1 expression, caused by JAM1 being missorted into lysosomes by HAX1 dysfunction.

AimTo assess the direct effect of intensive glycaemic control on periodontal tissues in patients with diabetes mellitus.Materials and MethodsTwenty-nine patients with type 2 diabetes were enrolled and hospitalized to receive a 2-week intensive glycaemic control regimen. We observed and analysed the systemic and oral disease indicators before and after treatment and clarified the indicators related to periodontal inflammation.ResultsA significant reduction in glycaemic and periodontal parameters, including glycated albumin levels and periodontal inflamed surface area (PISA), was observed after treatment. The changes in PISA per tooth, indicative of periodontal healing, exhibited a bimodal distribution; the patients were divided into two groups on this basis. Correlations were observed between the changes in PISA per tooth and fasting plasma glucose, acetoacetic acid, and beta-hydroxybutyrate levels in the PISA-improved group. Significantly lower levels of C-peptide, coefficient of variation of R-R interval, and ankle-brachial pressure index were observed before treatment in the PISA non-improved group.ConclusionsGlycaemic control treatment can effectively improve periodontitis in patients with type 2 diabetes, even in the absence of specific periodontal treatments. However, the periodontal responsiveness to glycaemic control treatment depends on the systemic condition of the patient.

Purpose: Missing teeth is one of the most important indicators of oral health behavior and the result of dental caries, periodontal disease, and injuries. This study examined a trend in the incidence of severe partial edentulism (SPE) using the Korean National Health Insurance Service (KNHIS) data. Materials and Methods: Data of adults aged >= 20 years were obtained from the KNHIS for the 2014-2018 period. SPE was defined in dental information within a population with a treatment history of dental scaling as having 1 to 8 natural teeth. Crude incidence rates (CIRs) and age -standardized incidence rates (AIRs) with 95% confidence interval were calculated per 100000 persons. The Cochran Armitage trend (CAT) test and average annual percentage change were used to analyze SPE trends. Results: The CIRs among Korean adults were from 346.29 to 391.11 in 2014-2016 and from 391.11 to 354.09 in 2016-2018. The AIRs trend statistically increased by 4.31% from 346.29 to 376.80 and decreased by 4.72% from 376.80 to 342.10. The AIRs in men increased by 4.00% and decreased by 3.01%. The AIRs in women decreased by 2.18% and increased by 2.11% (CAT; p<0.01). The AIRs by region and income also showed trends of increase and decrease. Conclusion: The study showed that the incidence trend of SPE increased and decreased from 2014 to 2018. This result would be able to aid in the planning of public oral health, and may also serve as fundamental data for verifying the impact of the public oral health policies implemented.

Background: Curcumin is a multi-functional polyphenol with anti-bacterial and anti-inflammatory effects and may have potential for treatment of periodontal diseases. The present study was conducted to examine the molecular basis of the anti-bacterial effect of curcumin against Porphyromonas gingivalis using metabolome analysis. Materials and Methods: P. gingivalis were incubated with 10 mu g/mL curcumin, and then metabolites were analyzed with CE-TOF/MS. Expression levels of sigma factors were also evaluated using RT-PCR assays. The activities of dipeptidyl peptidases (DPPs) were assessed by examining the degradation reactions of MCA-labeled peptides. Results: The relative amounts of various glycogenic amino acids were significantly decreased when P. gingivalis was incubated with curcumin. Furthermore, the metabolites on the amino acid degradation pathway, including high-energy compounds such as ATP, various intermediate metabolites of RNA/DNA synthesis, nucleoside sugars and amino sugars were also decreased. Additionally, the expression levels of sigma-54 and sigma-70 were significantly decreased, and the same results as noted following nutrient starvation. Curcumin also significantly suppressed the activities of some DPPs, while the human DPP-4 inhibitors markedly inhibited the growth of P. gingivalis and activities of the DPPs. Conclusions: Curcumin suppresses the growth of P. gingivalis by inhibiting DPPs and also interferes with nucleic acid synthesis and central metabolic pathways, beginning with amino acid metabolism.

The major oral odor compound methyl mercaptan (CH3SH) is strongly associated with halitosis and periodontitis. CH3SH production stems from the metabolism of polymicrobial communities in periodontal pockets and on the tongue dorsum. However, understanding of CH3SH-producing oral bacteria and their interactions is limited. This study aimed to investigate CH3SH production by major oral bacteria and the impact of interspecies interactions on its generation. Using a newly constructed large-volume anaerobic noncontact coculture system, Fusobacterium nucleatum was found to be a potent producer of CH3SH, with that production stimulated by metabolic interactions with Streptococcus gordonii, an early dental plaque colonizer. Furthermore, analysis of extracellular amino acids using an S. gordonii arginine-ornithine antiporter (ArcD) mutant demonstrated that ornithine excreted from S. gordonii is a key contributor to increased CH3SH production by F. nucleatum. Further study with 13C, 15N-methionine, as well as gene expression analysis, revealed that ornithine secreted by S. gordonii increased the demand for methionine through accelerated polyamine synthesis by F. nucleatum, leading to elevated methionine pathway activity and CH3SH production. Collectively, these findings suggest that interaction between S. gordonii and F. nucleatum plays a key role in CH3SH production, providing a new insight into the mechanism of CH3SH generation in oral microbial communities. A better understanding of the underlying interactions among oral bacteria involved in CH3SH generation can lead to the development of more appropriate prophylactic approaches to treat halitosis and periodontitis. An intervention approach like selectively disrupting this interspecies network could also offer a powerful therapeutic strategy.IMPORTANCEHalitosis can have a significant impact on the social life of affected individuals. Among oral odor compounds, CH3SH has a low olfactory threshold and halitosis is a result of its production. Recently, there has been a growing interest in the collective properties of oral polymicrobial communities, regarded as important for the development of oral diseases, which are shaped by physical and metabolic interactions among community participants. However, it has yet to be investigated whether interspecies interactions have an impact on the production of volatile compounds, leading to the development of halitosis. The present findings provide mechanistic insights indicating that ornithine, a metabolite excreted by Streptococcus gordonii, promotes polyamine synthesis by Fusobacterium nucleatum, resulting in a compensatory increase in demand for methionine, which results in elevated methionine pathway activity and CH3SH production. Elucidation of the mechanisms related to CH3SH production is expected to lead to the development of new strategies for managing halitosis.

OBJECTIVE:Dental implants are a considerable financial burden for elderly people and their caregivers. This study aimed to calculate the estimated economic costs of dental implants on the Korean older population. MATERIALS AND METHODS:The economic costs of dental implants for adults aged 75 years and older were estimated from a societal perspective, considering both direct and indirect expenditures. We used data from the Korean National Health Insurance Service for the period 2015-2018 to estimate the medical costs. Noninsured medical costs were estimated from research on medical expenses by the National Health Insurance Review and Assessment Service. Indirect costs related to transportation fees and time loss were obtained. The Cochran Armitage trend test was performed to examine the trend of the economic burden of dental implants. RESULTS:The estimated economic costs showed from 2015 to 2018 (total costs: $26.54-55.66 million, total costs after discount: $17.11-39.56 million). Direct costs, including insured and noninsured medical costs, represented from $25.81 to $47.03 million. Indirect costs, including transportation and time costs, ranged from $0.73 to $1.63 million. The impact of the total dental implant costs was 0.0018%-0.0034% of the Korean annual gross domestic product and 1.03%-1.59% of the annual total costs of dental care benefits. CONCLUSIONS:The estimated economic burden of dental implants significantly increased from 2015 to 2018 in older South Korean adults. These results will provide a foundation and guidance for further health economic studies on the burden of dental implants in the elderly population.

Solute carrier family 37 member 4 (SLC37A4) is known to regulate glucose-6-phosphate transport from cytoplasm to the lumen of the endoplasmic reticulum, which serves to maintain glucose homeostasis. Glycogen storage disease type 1b (GSD1b) is caused by a mutation of SLC37A4, leading to a glycogenolysis defect. Although GSD1b cases are known to be complicated by periodontitis, the etiological molecular basis remains unclear. The present study investigated the effects of SLC37A4 on gingival barrier function. Examinations of immortalized human gingival epithelial (IHGE) cells showed SLC37A4 localized in the endoplasmic reticulum. SLC37A4 knockout decreased expression of JAM1, a tight junction-related protein, in IHGE cells. Using in silico analysis to investigate potential transcription factor binding sites, H6 family homeobox 3 (HMX3) was shown to be related to JAM1 expression. In HMX3-knockdown IHGE cells, JAM1 expression was markedly suppressed. Furthermore, HMX3 was scarcely detected in SLC37A4-knockout cells, while HMX3 overexpression restored JAM1 expression in those cells. Finally, using a three-dimensional multilayered gingival epithelial tissue model, knockout of SLC37A4 was also found to increase permeability to lipopolysaccharide and peptidoglycan, which was dependent on JAM1 expression. Specific downregulation of HMX3 by SLC37A4 and the consequent decrease in JAM1 expression provides findings indicating a molecular basis for the reduction in barrier function of gingival epithelial tissues in GSD1b cases.

We previously showed that junctional adhesion molecule 1 (JAM1) and coxsackievirus and adenovirus receptor (CXADR), tight junction-associated proteins, have important roles to maintain epithelial barrier function in gingival tissues. Smoking is considered to be a significant risk factor for periodontal disease. The present study was conducted to examine the effects of cigarette smoke extract (CSE) on JAM1 and CXADR in human gingival epithelial cells. CSE was found to cause translocation of JAM1 from the cellular surface to EGFR-positive endosomes, whereas CXADR did not. Using a three-dimensional multilayered gingival epithelial tissue model, CSE administration was found to increase permeability to lipopolysaccharide and peptidoglycan, whereas overexpression of JAM1 in the tissue model prevented penetration by those substrates. Furthermore, vitamin C increased JAM1 expression, and inhibited penetration of LPS and PGN induced by CSE. These findings strongly suggest that CSE disrupts gingival barrier function via dislocation of JAM1, thus allowing bacterial virulence factors to penetrate into subepithelial tissues. Furthermore, they indicate that vitamin C increases JAM1 expression and prevents disruption of gingival barrier function by CSE.

This study explored the epidemiological role of central adiposity and body mass index (BMI) in terms of clinical attachment loss (CAL)/pocket depth (PD) and metabolic syndrome components. This study included data from the National Health and Nutrition Examination Survey III of America on 12,254 adults aged 20 years of age or older with a blood sample, anthropometric measurements, and a periodontal examination. Clinical periodontitis measurements, including CAL and PD, were classified into quintiles or quartiles and compared. CAL was positively associated with central adiposity, hypertension, and hyperglycemia; the relationship between CAL and diabetes was stronger when central adiposity was absent (odds ratio [OR] and 95% confidence interval: 6.33, 2.14–18.72 vs. 3.14, 1.78–5.56). The relationship between CAL and impaired fasting glucose (IFG) differed slightly with BMI. The IFG ORs for normal, overweight, and obese patients were 1.63 (1.08–2.45), 1.76 (1.05–2.97), and 1.43 (0.88–2.30), respectively. CAL was positively correlated with all metabolic syndrome components except hypertriglyceridemia. Associations between CAL, diabetes, and IFG significantly varied with BMI. Periodontitis in individuals without central obesity or with normal bodyweight may independently indicate diabetes and IFG. Therefore, preventive measures against periodontitis without obesity are necessary to improve general and oral health.

OBJECTIVES Population aging is rapidly accelerating worldwide. Oral diseases related to aging are also on the rise. This study examined trends in the incidence of edentulism among the older Korean population using data from the Korean National Health Insurance Service (KNHIS). METHODS Data on older adults, aged ≥75 years of age, were obtained from the KNHIS for the period 2013-2018. Edentulism was defined as a treatment history of complete dentures in the KNHIS database. The exclusion criteria consisted of both disease codes and treatment codes related to conservative dental treatment, including periodontal and extraction treatment afterward. Crude incidence rates (CIRs) and age-standardized incidence rates (AIRs) with 95% confidence intervals were calculated and reported per 100,000 person-years by the direct method. Trends were tested by Cochrane Armitage models. RESULTS Statistically significant increasing trends in both CIRs and AIRs were found among the older Korean population registered in the KNHIS (CIRs, 707.92 to 895.92; AIRs, 705.11 to 889.68; p<0.01). The incidence tended to increase in both genders (p<0.01). Both CIRs and AIRs in specific regions also showed slight but significant annual increases except for Jeju Island (p<0.01 or <0.05). The incidence showed increasing trends (p<0.01) in all income quintiles apart from the highest quintile. The edentulism incidence was highest in the lowest income group (the first quintile). CONCLUSIONS Our data showed that the incidence of edentulism among the elderly showed an increasing trend from 2013 to 2018. This result provides a basis for future epidemiological studies on the incidence of edentulism in the older Korean population.

OBJECTIVE:Chronic periodontitis is caused by multiple risk factors. To predict chronic periodontitis in older people, we evaluated the association between a combination of major periodontal pathogens and salivary biomarkers and the presence of periodontitis.METHODS:Stimulated saliva samples were collected to analyze the prevalence of Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia, and Prevotella intermedia, as well as four biomarkers: interleukin (IL)-1β, IL-6, tumor necrosis factor-α (TNF-α), and prostaglandin E2 (PGE2). A total of 201 Japanese patients were recruited. Oral examinations ware performed to determine chronic periodontitis as measured by Community Periodontal Index. The sociodemographic and behavioral characteristics were also obtained, and the parameters were adjusted as potential confounders to employ statistical models.RESULTS:The odds ratio (OR) for the presence of P. gingivalis and the third tertile level of IL-1β as compared with the absence of P. gingivalis and the lowest tertile of IL-1β was highest in individuals with periodontitis (OR = 13.98; 95% confidence interval [CI] 3.87-50.52) with the best level (0.79) of area under the curve (AUC) based on the receiver operating characteristic curve. The OR for the presence of P. gingivalis and the third tertile of PGE2 was 7.76 (CI 1.89-31.91) with an AUC of 0.78. The coexistence of more than two periodontal bacteria and the third tertile of PGE2 was also strongly associated with chronic periodontitis (OR = 9.23, 95% CI 2.38-35.79) with an AUC of 0.76.CONCLUSIONS:The combined information of the presence of P. gingivalis in stimulated saliva, and higher levels of salivary IL-1β may play a vital role in the detection and prediction of chronic periodontitis in older adults.

Halitosis is formed mainly by the volatile compounds produced by periodontal bacteria. Three volatile sulfur compounds (VSCs), hydrogen sulfide, methanethiol, and dimethyl sulfide, have attracted attention as major components of halitosis. However, these compounds cannot account for all odors. In this study, we profiled volatile compounds from the culture supernatants of periodontal bacteria using gas chromatography/mass spectrometry/olfactometry analysis with a monolithic silica gel adsorption device to investigate the potential odorous compounds. Periodontal bacteria have been found to produce volatile compounds belonging to various classes, such as alcohols, ketones, fatty acids, and aromatic compounds, in addition to VSCs. In addition, VSCs different from hydrogen sulfide and methanethiol, which are considered important causative compounds, may also influence to halitosis.

Fusobacterium nucleatum is a common constituent of the oral microbiota in both periodontal health and disease. Previously, we discovered ornithine cross-feeding between F. nucleatum and Streptococcus gordonii, where S. gordonii secretes ornithine via an arginine-ornithine antiporter (ArcD), which in turn supports the growth and biofilm development of F. nucleatum; however, broader metabolic aspects of F. nucleatum within polymicrobial communities and their impact on periodontal pathogenesis have not been addressed. Here, we show that when cocultured with S. gordonii, F. nucleatum increased amino acid availability to enhance the production of butyrate and putrescine, a polyamine produced by ornithine decarboxylation. Coculture with Veillonella parvula, another common inhabitant of the oral microbiota, also increased lysine availability, promoting cadaverine production by F. nucleatum. We confirmed that ArcD-dependent S. gordonii-excreted ornithine induces synergistic putrescine production, and mass spectrometry imaging revealed that this metabolic capability creates a putrescine-rich microenvironment on the surface of F. nucleatum biofilms. We further demonstrated that polyamines caused significant changes in the biofilm phenotype of a periodontal pathogen, Porphyromonas gingivalis, with putrescine accelerating the biofilm life cycle of maturation and dispersal. This phenomenon was also observed with putrescine derived from S. gordonii-F. nucleatum coculture. Lastly, analysis of plaque samples revealed cooccurrence of P. gingivalis with genetic modules for putrescine production by S. gordonii and F. nucleatum. Overall, our results highlight the ability of F. nucleatum to induce synergistic polyamine production within multispecies consortia and provide insight into how the trophic web in oral biofilm ecosystems can eventually shape disease-associated communities. IMPORTANCE Periodontitis is caused by a pathogenic shift in subgingival biofilm ecosystems, which is accompanied by alterations in microbiome composition and function, including changes in the metabolic activity of the biofilm, which comprises multiple commensals and pathogens. While Fusobacterium nucleatum is a common constituent of the supra- and subgingival biofilms, its metabolic integration within polymicrobial communities and the impact on periodontal pathogenesis are poorly understood. Here, we report that amino acids supplied by other commensal bacteria induce polyamine production by F. nucleatum, creating polyamine-rich microenvironments. Polyamines reportedly have diverse functions in bacterial physiology and possible involvement in periodontal pathogenesis. We show that the F. nucleatum-integrated trophic network yielding putrescine from arginine through ornithine accelerates the biofilm life cycle of Porphyromonas gingivalis, a periodontal pathogen, from the planktonic state through biofilm formation to dispersal. This work provides insight into how cooperative metabolism within oral biofilms can tip the balance toward periodontitis.

Surface pre-reacted glass-ionomer (S-PRG) filler, produced by PRG technology for use with various dental materials, is bioactive and known to release ions from a glass-ionomer phase. We previously reported that coxsackievirus and adenovirus receptor (CXADR), a tight junction associated protein, was located in the epithelial barrier of gingival epithelium. In the present study, the tissue protective effects of an S-PRG eluate prepared with S-PRG filler were investigated using a three-dimensional human gingival epithelial tissue model. The results showed that the S-PRG eluate specifically induced CXADR expression at the transcriptional level of messenger RNA as well as the protein level, and also nuclear translocation of transcription factor EB (TFEB) in gingival epithelial cells. Furthermore, shigyakusan, a TFEB inhibitor, canceled induction of the CXADR protein by the S-PRG eluate. Additionally, gingival epithelial permeation by 40-kDa dextran, lipopolysaccharide, and peptidoglycan in the 3D-tissue models was prevented by the eluate, with those effects abrogated by knockdown of CXADR. These findings suggest that S-PRG eluate increases CXADR expression via the TFEB pathway, thus inhibiting penetration of bacterial virulence factors into subepithelial tissues.

Periodontal diseases initiate on epithelial surfaces of the subgingival compartment, while the gingival epithelium functions as an epithelial barrier against microbial infection and orchestrates immune responses. Porphyromonas gingivalis is a major pathogen of periodontal diseases and has an ability to penetrate the epithelial barrier. To assess the molecular basis of gingival epithelial barrier dysfunction associated with P. gingivalis, we newly developed a three-dimensional multilayered tissue model of gingival epithelium with gene manipulation. Using this novel approach, P. gingivalis gingipains including Arg- or Lys-specific cysteine proteases were found to specifically degrade junctional adhesion molecule 1 and coxsackievirus and adenovirus receptor in the tissue model, leading to increased permeability for lipopolysaccharide, peptidoglycan, and gingipains. This review summarizes the strategy used by P. gingivalis to disable the epithelial barrier by disrupting specific junctional adhesion molecules.