Natsumi Fujiwara

Oral Porphyromonas gingivalis translocates to the liver and regulates hepatic glycogen synthesis through the Akt/GSK-3β signaling pathway

Periodontal diseases are common chronic inflammatory disorders that result in the destruction of tissues around teeth. Many clinical studies suggest that periodontal diseases are risk factors for insulin resistance and diabetic mellitus development. However, the molecular mechanisms by which periodontal diseases regulate the progress of diabetes mellitus remain unknown. In this study, we investigated whether Porphyromonas gingivalis (P.g.), a major pathogen of periodontal diseases, present in the oral cavity, moves to the liver and affects hepatic glycogen synthesis. SNAP26b-tagged P.g. (SNAP-P.g.) was introduced into the oral cavity to induce periodontal disease in 4-week old female Balb/c mice. SNAP-P.g. was detected in the liver extracted from SNAP-P.g.-treated mice using nested PCR analysis. High blood glucose levels tended to promote SNAP-P.g. translocation from the oral cavity to the liver in mice. Periodic acid-Schiff staining suggested that hepatic glycogen synthesis decreased in SNAP-P.g.-treated mice. SNAP-P.g. was also internalized into the human hepatoma cell line HepG2, and this attenuated the phosphorylation of insulin receptor substrate (IRS)-1, Akt and glycogen synthase kinase-3β induced by insulin. Insulin-induced glycogen synthesis was suppressed by SNAP-P.g. in HepG2 cells. Our results suggest that P.g. translocation from the oral cavity to the liver may contribute to the progress of diabetes mellitus by influencing hepatic glycogenesis.

Anti‐inflammatory and protective effects of 2‐methacryloyloxyethyl phosphorylcholine polymer on oral epithelial cells

Periodontitis is a chronic inflammatory disease initiated by a microbial biofilm formed in the periodontal pocket. Gingival epithelium plays important roles as the first physical barrier to bacterial invasion and in orchestrating the innate immune reaction via toll-like receptors (TLRs), which recognize various bacterial products, and maintaining its function. Newly developed oral care products to inhibit bacterial adherence, subsequent inflammatory reaction and protect the gingival epithelium are expected. We previously reported that 2-methacryloyloxyethyl phosphorylcholine (MPC)-polymer coating decreased bacterial adhesion to human oral keratinocytes, RT-7, and mouth-rinsing with MPC-polymer inhibited the increase of oral bacteria. In this study, regarding the possibility of MPC-polymer application for preventing the adherence of periodontal pathogen, subsequent inflammatory reaction and protection of gingival epithelium, we examined the effects of MPC-polymer on the adherence of Porphyromonas gingivalis, major periodontitis-related pathogen, and TLR2 ligand to RT-7 and subsequent interleukin (IL)-8 production. MPC-polymer treatment significantly reduced P. gingivalis adherence by 44% and TLR2-mediated IL-8 production by blocking the binding of its specific-ligand in a concentration-dependent manner. Furthermore, MPC-polymer pretreatment protected RT-7 from injury by chemical irritants, cetylpyridinium chloride. These findings suggest that MPC-polymer is potentially useful for oral care to prevent oral infection and to maintain oral epithelial function.

Oral environment and cancer

Cancer is now the leading cause of death in Japan. A rapid increase in cancer mortality is expected as Japan is facing a super-aged society. Many causes of cancer are known to be closely linked to life style factors, such as smoking, drinking, and diet. The oral environment is known to be involved in the pathogenesis and development of various diseases such as bronchitis, pneumonia, diabetes, heart disease, and dementia. Because the oral cavity acts as the bodily entrance for air and food, it is constantly exposed to foreign substances, including bacteria and viruses. A large number of bacteria are endemic to the oral cavity, and indigenous oral flora act to prevent the settlement of foreign bacteria. The oral environment is influenced by local factors, including dental plaque, tartar, teeth alignment, occlusion, an incompatible prosthesis, and bad lifestyle habits, and systemic factors, including smoking, consumption of alcohol, irregular lifestyle and eating habits, obesity, stress, hormones, and heredity. It has recently been revealed that the oral environment is associated with cancer. In particular, commensal bacteria in the oral cavity are involved in the development of cancer. Moreover, Candida, human papilloma virus and Epstein-Barr virus as well as commensal bacteria have been reported to be associated with the pathogenesis of cancer. In this review, we introduce recent findings of the correlation between the oral environment and cancer.

Human odontogenic epithelial cells derived from epithelial rests of Malassez possess stem cell properties

Epithelial cell rests of Malassez (ERM) are quiescent epithelial remnants of the Hertwig’s epithelial root sheath (HERS) that are involved in the formation of tooth roots. ERM cells are unique epithelial cells that remain in periodontal tissues throughout adult life. They have a functional role in the repair/regeneration of cement or enamel. Here, we isolated odontogenic epithelial cells from ERM in the periodontal ligament, and the cells were spontaneously immortalized. Immortalized odontogenic epithelial (iOdE) cells had the ability to form spheroids and expressed stem cell-related genes. Interestingly, iOdE cells underwent osteogenic differentiation, as demonstrated by the mineralization activity in vitro in mineralization-inducing media and formation of calcification foci in iOdE cells transplanted into immunocompromised mice. These findings suggest that a cell population with features similar to stem cells exists in ERM and that this cell population has a differentiation capacity for producing calcifications in a particular microenvironment. In summary, iOdE cells will provide a convenient cell source for tissue engineering and experimental models to investigate tooth growth, differentiation, and tumorigenesis.

Preventive Effects of Houttuynia cordata Extract for Oral Infectious Diseases

Houttuynia cordata (HC) (Saururaceae) has been used internally and externally as a traditional medicine and as an herbal tea for healthcare in Japan. Our recent survey showed that HC poultice (HCP) prepared from smothering fresh leaves of HC had been frequently used for the treatment of purulent skin diseases with high effectiveness. Our experimental study also demonstrated that ethanol extract of HCP (eHCP) has antibacterial, antibiofilm, and anti-inflammatory effects against S. aureus which caused purulent skin diseases. In this study, we focused on novel effects of HCP against oral infectious diseases, such as periodontal disease and dental caries. We determined the antimicrobial and antibiofilm effects of water solution of HCP ethanol extract (wHCP) against important oral pathogens and investigated its cytotoxicity and anti-inflammatory effects on human oral epithelial cells. wHCP had moderate antimicrobial effects against some oral microorganisms and profound antibiofilm effects against Fusobacterium nucleatum, Streptococcus mutans, and Candida albicans. In addition, wHCP had no cytotoxic effects and could inhibit interleukin-8 and CCL20 productions by Porphyromonas gingivalis lipopolysaccharide-stimulated human oral keratinocytes. Our findings suggested that wHCP may be clinically useful for preventing oral infectious diseases as a mouthwash for oral care.

Antibiofilm and Anti-Inflammatory Activities of Houttuynia cordata Decoction for Oral Care

Dental biofilms that form in the oral cavity play a critical role in the pathogenesis of several infectious oral diseases, including dental caries, periodontal disease, and oral candidiasis. Houttuynia cordata (HC, Saururaceae) is a widely used traditional medicine, for both internal and external application. A decoction of dried HC leaves (dHC) has long been consumed as a health-promoting herbal tea in Japan. We have recently reported that a water solution of HC poultice ethanol extract (wHCP) exerts antimicrobial and antibiofilm effects against several important oral pathogens. It also exhibits anti-inflammatory effects on human keratinocytes. In our current study, we examined the effects of dHC on infectious oral pathogens and inflammation. Our results demonstrated that dHC exerts moderate antimicrobial effects against methicillin-resistant Staphylococcus aureus (MRSA) and other oral microorganisms. dHC also exhibited antibiofilm effects against MRSA, Fusobacterium nucleatum (involved in dental plaque formation), and Candida albicans and inhibitory effects on interleukin-8, CCL20, IP-10, and GROα productions by human oral keratinocytes stimulated by Porphyromonas gingivalis lipopolysaccharide (a cause of periodontal disease), without cytotoxic effects. This suggests that dHC exhibits multiple activities in microorganisms and host cells. dHC can be easily prepared and may be effective in preventing infectious oral diseases.

Porphyromonas gingivalis attenuates the insulin-induced phosphorylation and translocation of forkhead box protein O1 in human hepatocytes

OBJECTIVE Porphyromonas gingivalis (P. gingivalis) is a pathogen involved in periodontal disease. Recently, periodontal disease has been demonstrated to increase the risk of developing diabetes mellitus, although the molecular mechanism is not fully understood. Forkhead box protein O1 (FoxO1) is a transcriptional factor that regulates gluconeogenesis in the liver. Gluconeogenesis is a key process in the induction of diabetes mellitus; however, little is known regarding the relationship between periodontal disease and gluconeogenesis. In this study, to investigate whether periodontal disease influences hepatic gluconeogenesis, we examined the effects of P. gingivalis on the phosphorylation and translocation of FoxO1 in insulin-induced human hepatocytes. DESIGN The human hepatocyte HepG2 was treated with insulin and Akt and FoxO1 phosphorylation was detected by western blot analysis. The localization of phosphorylated FoxO1 was detected by immunocytochemistry and western blot analysis. HepG2 cells were treated with SNAP26b-tagged P. gingivalis (SNAP-P.g.) before insulin stimulation, and then the changes in Akt and FoxO1 were determined by western blot analysis and immunocytochemistry. RESULTS Insulin (100nM) induced FoxO1 phosphorylation 60min after treatment in HepG2 cells. Phosphorylated FoxO1 translocated to the cytoplasm. SNAP-P.g. internalized into HepG2 cells and decreased Akt and FoxO1 phosphorylation induced by insulin. The effect of insulin on FoxO1 translocation was also attenuated by SNAP-P.g. CONCLUSIONS Our study shows that P. gingivalis decreases the phosphorylation and translocation of FoxO induced by insulin in HepG2 cells. Our results suggest that periodontal disease may increase hepatic gluconeogenesis by reducing the effects of insulin on FoxO1.

Preventive effects of mouthguard use while sleeping on recurrent aphthous stomatitis: Preliminary interventional study

Recurrent aphthous stomatitis (RAS) is the most common inflammatory ulceration in the oral mucosa of otherwise healthy individuals and is often accompanied by severe pain. However, the etiology of RAS is not completely understood, and currently, no therapy can completely prevent RAS recurrence. In our clinical experience, we noticed that patients using a night guard, which is often used for bruxism treatment, did not develop RAS. Therefore, the aim of this study was to determine whether mouthguard use can suppress RAS development. The cohort of this interventional, prospective, single‐center, and self‐controlled study included 20 subjects who developed RAS at least once a month. The oral health of all the subjects was recorded for 60 days before and after intervention with a mouthguard. The average number of RAS incidences decreased from 5.5 to 1.0, the average days until healing decreased from 7.3 to 5.6, and the period with RAS decreased from 31.5 to 5.0 with mouthguard use. Mouthguard use may be beneficial for preventing RAS development.