The Germinal Origin of Salivary and Lacrimal Glands and the Contributions of Neural Crest Cell-Derived Epithelium to Tissue Regeneration.

The vertebrate body comprises four distinct cell populations: cells derived from (1) ectoderm, (2) mesoderm, (3) endoderm, and (4) neural crest cells, often referred to as the fourth germ layer. Neural crest cells arise when the neural plate edges fuse to form a neural tube, which eventually develops into the brain and spinal cord. To date, the embryonic origin of exocrine glands located in the head and neck remains under debate. In this study, transgenic TRiCK mice were used to investigate the germinal origin of the salivary and lacrimal glands. TRiCK mice express fluorescent proteins under the regulatory control of Sox1, T/Brachyury, and Sox17 gene expressions. These genes are representative marker genes for neuroectoderm (Sox1), mesoderm (T), and endoderm (Sox17). Using this approach, the cellular lineages of the salivary and lacrimal glands were examined. We demonstrate that the salivary and lacrimal glands contain cells derived from all three germ layers. Notably, a subset of Sox1-driven fluorescent cells differentiated into epithelial cells, implying their neural crest origin. Also, these Sox1-driven fluorescent cells expressed high levels of stem cell markers. These cells were particularly pronounced in duct ligation and wound damage models, suggesting the involvement of neural crest-derived epithelial cells in regenerative processes following tissue injury. This study provides compelling evidence clarifying the germinal origin of exocrine glands and the contribution of neural crest-derived cells within the glandular epithelium to the regenerative response following tissue damage.

Evaluation of oral care using MA-T gel for high-risk patients: a pilot study.

BACKGROUND: Oral care with gel is a common method for preventing aspiration in high-risk patients. An oral care gel is used to clean and moisturize the oral cavity. However, the effects of gel care on the oral bacteria remain unclear. In this pilot study, we described a matching transformation system (MA-T) for elderly high-risk patients. MA-T is an on-demand aqueous chlorine dioxide solution that provides excellent safety and has various antimicrobial activities, even in the presence of abundant organic compounds. This study investigated the effects of MA-T gel in patients requiring nursing care. MATERIALS AND METHODS: Patients who were hospitalized for nursing care were included in this study. No drugs and foods were administered orally. Oral bacteria and intraoral humidity were examined by daily care using MA-T gel. Moreover, oral membranous substances were analyzed and material from the oral cavity was cultured on selective media for identifying opportunistic organisms. RESULTS: Membranous substances were present in the oral cavities of all patients. The number of bacteria decreased, and oral moisture improved, after treatment with MA-T gel. Moreover, oral humidity was also controlled with the continued use of MA-T gel. MA-T gels should be used not only for professional care but also on a daily basis for better oral care. Furthermore, the results of bacterial cultures showed that MA-T controls the propagation of opportunistic bacterial infections. CONCLUSION: Membranous substances may be observed in the oral cavity of individuals requiring nursing care for tube feeding. The results of this pilot study suggest that MA-T, a novel disinfectant, can be used for oral care in the elderly to reduce the risk of aspiration-pneumonia.

Evaluation of the Saxon test for patients with hyposalivation without Sjögren's syndrome.

BACKGROUND: Dry mouth is associated with salivary gland hypofunction, which may result from several conditions such as Sjögren's syndrome (SS), head and neck cancers, and side effects of medications. The Saxon test is a useful diagnostic method for hyposalivation in clinical settings. However, previous reports indicate that the test has mostly been used for patients with SS. OBJECTIVE(S): In the present study, we focused on patients with dry mouth who were not diagnosed with SS (patients without SS). METHODS: For patients without SS (n = 302), we examined the factors affecting Saxon test scores using multiple regression analysis. Additionally, we performed a correlation analysis comparing the Saxon test with other diagnostic methods. RESULTS: In 57.6% patients, the Saxon test score was more than 2.00 g/2 min, which is considered negative for hyposalivation. Multiple regression analysis revealed that the age and sex of patients significantly influenced test scores. The mean Saxon test score was less than 2.00 g/2 min in older patients and women. Moreover, the test showed a significant correlation with other methods used to measure salivary flow. CONCLUSION: The Saxon test is useful not only for patients with SS but also for patients without SS.

Morphological differences between regenerating salivary glands after salivary gland duct ligation and embryonic salivary glands.

BACKGROUND: Most animals and organs have regenerative capabilities. Whether regeneration is a developmental process or a distinct phenomenon that is independent of development is debatable. METHOD: We examined the differences between developing and regenerating salivary glands using duct-ligation models. We performed morphological analyses comparing submandibular gland regeneration and development. To reveal the proliferation processes that occur during salivary gland regeneration and development, we counted the number of Ki67-positive cells over time. In addition, we examined the expression of the following markers: aquaporin 5, smooth muscle actin, cytokeratin 7, and tubulin beta 3. RESULT: The proliferation patterns seen during regeneration differed from those observed during development. Different salivary gland marker expression patterns were seen during development and regeneration. CONCLUSION: This study showed that regenerating salivary glands do not follow the same growth process as developing salivary glands.

Anterior cleft palate due to Cbfb deficiency and its rescue by folic acid.

Core binding factor ß (Cbfb) is a cofactor of the Runx family of transcription factors. Among these transcription factors, Runx1 is a prerequisite for anterior-specific palatal fusion. It was previously unclear, however, whether Cbfb served as a modulator or as an obligatory factor in the Runx signaling process that regulates palatogenesis. Here, we report that Cbfb is essential and indispensable in mouse anterior palatogenesis. Palatal fusion in Cbfb mutants is disrupted owing to failed disintegration of the fusing epithelium specifically at the anterior portion, as observed in Runx1 mutants. In these mutants, expression of TGFB3 is disrupted in the area of failed palatal fusion, in which phosphorylation of Stat3 is also affected. TGFB3 protein has been shown to rescue palatal fusion in vitro TGFB3 also activated Stat3 phosphorylation. Strikingly, the anterior cleft palate in Cbfb mutants is further rescued by pharmaceutical application of folic acid, which activates suppressed Stat3 phosphorylation and Tgfb3 expression in vitro With these findings, we provide the first evidence that Cbfb is a prerequisite for anterior palatogenesis and acts as an obligatory cofactor in the Runx1/Cbfb-Stat3-Tgfb3 signaling axis. Furthermore, the rescue of the mutant cleft palate using folic acid might highlight potential therapeutic targets aimed at Stat3 modification for the prevention and pharmaceutical intervention of cleft palate.

Role of the mTOR signalling pathway in salivary gland development.

Development of the salivary gland is characterized by extensive branching morphogenesis. Although various molecules have been implicated in salivary gland development, the role of the mammalian target of rapamycin (mTOR) signalling pathway, including both mTOR complexes 1 and 2 (mTORC1 and 2), in salivary gland development is unknown. Here, we examined protein expression levels related to the mTOR signalling pathway using an ex vivo submandibular salivary gland (SMG) organ culture. We showed that branching buds in the salivary glands were substantially decreased and phosphorylation of mTORC1 signalling pathway related proteins (mTOR, p70 ribosomal protein S6 kinase 1 and eukaryotic initiation factor 4E-binding protein 1) was inhibited by rapamycin (an mTOR inhibitor). In addition, AKT, which is an upstream protein kinase of mTORC1 and is downstream of mTORC2, is inhibited by LY294002 (a phosphatidylinositol 3-kinase inhibitor), but not by rapamycin. Moreover, rapamycin-treated ICR neonatal mice exhibited a reduction in both body weight and salivary glands compared with vehicle-treated neonatal mice. The present data indicate that the mTOR signalling pathway, including both mTORC1 and mTORC2, plays a critical role in salivary gland development both in ex vivo SMG organ culture and ICR neonatal mice in vivo.

The efficacy of nasal airway stent (Nastent) on obstructive sleep apnoea and prediction of treatment outcomes.

BACKGROUND: Obstructive sleep apnoea (OSA) is characterised by recurrent episodes of partial or complete upper airway collapse during sleep and is highly prevalent in the general population. The nasopharyngeal airway stent (Nastent) is a specifically designed, preformed silicone tube that intends to maintain the upper airway patency during sleep and reduce snoring and sleep apnoea. OBJECTIVE(S): The purpose of this study was to determine the efficacy of Nastent treatment and examine predictors for Nastent treatment outcomes in patients with OSA. METHODS: Consecutive thirty patients were enrolled in this study. Cephalometric radiographs were obtained to analyse the pharyngeal and craniofacial morphology. Before and after Nastent treatment, we evaluated OSA using a portable sleep study. RESULTS: Twenty-nine subjects completed this study. There were significant decreases in the respiratory event index (REI) (22.4 ± 14.1 to 15.7 ± 10.4, P < 0.01) and a significant increase in the lowest SpO2 (81.9 ± 7.5 to 86.6 ± 4.8, P < 0.01) by Nastent treatment. Subjects were divided into responders and non-responders based on reduction in REI of >50% compared with baseline REI. We evaluated the ratio of inferior airway width and middle airway width (IAW/MAW) on cephalograms as the index of the narrowest airway site. The IAW/MAW was significantly higher in responders than in non-responders (1.4 ± 0.9 vs 0.9 ± 0.4, P < 0.01) and predicted treatment responders with high accuracy (sensitivity: 90.9%, specificity: 88.9%, when IAW/MAW was set at 1.10). CONCLUSIONS: The Nastent device improved OSA, and a narrower velopharynx than hypopharynx predicted treatment response with a good sensitivity and specificity.

Runx1-Stat3-Tgfb3 signaling network regulating the anterior palatal development.

Runx1 deficiency results in an anteriorly specific cleft palate at the boundary between the primary and secondary palates and in the first rugae area of the secondary palate in mice. However, the cellular and molecular pathogenesis underlying such regional specificity remain unknown. In this study, Runx1 epithelial-specific deletion led to the failed disintegration of the contacting palatal epithelium and markedly downregulated Tgfb3 expression in the primary palate and nasal septum. In culture, TGFB3 protein rescued the clefting of the mutant. Furthermore, Stat3 phosphorylation was disturbed in the corresponding cleft regions in Runx1 mutants. The Stat3 function was manifested by palatal fusion defects in culture following Stat3 inhibitor treatment with significant downregulation of Tgfb3. Tgfb3 is therefore a critical target of Runx1 signaling, and this signaling axis could be mediated by Stat3 activation. Interestingly, the expression of Socs3, an inhibitor of Stat3, was specific in the primary palate and upregulated by Runx1 deficiency. Thus, the involvement of Socs3 in Runx1-Tgfb3 signaling might explain, at least in part, the anteriorly specific downregulation of Tgfb3 expression and Stat3 activity in Runx1 mutants. This is the first study to show that the novel Runx1-Stat3-Tgfb3 axis is essential in anterior palatogenesis.

Runx1-Stat3 signaling regulates the epithelial stem cells in continuously growing incisors.

Rodent incisors grow permanently and the homeostasis of enamel production is maintained by a continuous supply of epithelial progenitors from putative stem cells in the cervical loop. We herein report that Runx1 regulates the Lgr5-expressing epithelial stem cells and their subsequent continuous differentiation into ameloblasts. Mice deficient in epithelial Runx1 demonstrate remarkable shortening of the incisors with underdevelopment of the cervical loop and enamel defects. In this mutant cervical loop, the proliferation of the dental epithelium was significantly disturbed and the expression of Lgr5 and enamel matrix proteins was remarkably downregulated. Interestingly, the expression of Socs3, an inhibitor of Stat3 signaling, was upregulated and Stat3 phosphorylation was suppressed specifically in the mutant cervical loop. The expression of Lgr5 and the enamel matrix protein in the wild-type incisor germs is disturbed by pharmaceutical Stat3 inhibition in vitro., of. Conversely, pharmaceutical activation of Stat3 rescues the defective phenotypes of the Runx1 mutant with upregulated Lgr5 and enamel matrix protein genes. The present results provide the first evidence of the role of Runx1 regulates the Lgr5-expressing epithelial stem cells and differentiation of ameloblast progenitors in the developing incisors. Our study also demonstrates that Stat3 modulates the Runx1-Lgr5 axis in the cervical loop.

Dental and skeletal changes associated with long-term oral appliance use for obstructive sleep apnea: A systematic review and meta-analysis.

An oral appliance (OA) is an effective treatment option for patients with obstructive sleep apnea (OSA), but dental and skeletal changes have been detected by many studies after long-term OA use. Better understanding of the long-term side effects may decrease discontinuation of OA use and assist clinicians to make informed decisions. Accordingly, a systematic review and meta-analysis were performed to evaluate the dental and skeletal changes associated with OAs designed to advance the mandible. The quality of the studies was determined by using the risk of bias assessment tool for non-randomized studies (RoBANS), and 12 studies were included in the meta-analysis. OA use was associated with a significant decrease of overjet (OJ) and overbite (OB), and it was suggested that both parameters decreased along with the duration of treatment. Meta-analysis also demonstrated a significant increase of L1-MP. However, there were no significant changes of skeletal modifications or mandibular rotation. Changes of incisor inclination were suggested to make a contribution to reduction of OJ and OB. In conclusion, long-term OA use was associated with dental changes. The results of this study provide information for clinicians about the long-term effects of OAs.

Runx1 mediates the development of the granular convoluted tubules in the submandibular glands.

The mouse granular convoluted tubules (GCTs), which are only located in the submandibular gland (SMG) are known to develop and maintain their structure in an androgen-dependent manner. We previously demonstrated that the GCTs are involuted by the epithelial deletion of core binding factor ß (CBFß), a transcription factor that physically interacts with any of the Runt-related transcription factor (RUNX) proteins (RUNX1, 2 and 3). This result clearly demonstrates that the Runx /Cbfb signaling pathway is indispensable in the development of the GCTs. However, it is not clear which of the RUNX proteins plays useful role in the development of the GCTs by activating the Runx /Cbfb signaling pathway. Past studies have revealed that the Runx /Cbfb signaling pathway plays important roles in various aspects of development and homeostatic events. Moreover, the Runx genes have different temporospatial requirements depending on the biological situation. In the present study, the GCTs of the SMG showed a remarkable phenotype of, which phenocopied the epithelial deletion of Cbfb, in epithelial-specific Runx1 conditional knock-out (cKO) mice. The results indicate that Runx1 works as a partner of Cbfb during the development of the GCTs. We also discovered that the depletion of Runx1 resulted in the reduced secretion of saliva in male mice. Consistent with this finding, one of the water channels, Aquaporin-5 (AQP5) was mislocalized in the cytoplasm of the Runx1 mutants, suggesting a novel role of Runx1 in the membrane trafficking of AQP5. In summary, the present findings demonstrated that RUNX1 is essential for the development of the GCTs. Furthermore, RUNX1 could also be involved in the membrane trafficking of the AQP5 protein of the acinar cells in the SMG in order to allow for the proper secretion of saliva.