Yohei Kamata

Induction of β-Defensin Expression by Porphyromonas gingivalis-Infected Human Gingival Graft Transplanted in nu/nu Mouse Subdermis

It is important to understand the onset of periodontal disease in terms of bacterial infection and host factors. Host-bacteria interactions can be elicited in human cultured cells and animal models, but these models provide only limited biological information about human host reactions against bacterial attacks. Development of an in vivo model using human gingival tissue is needed. We established an in vivo model using nu/nu mice and evaluated host defense following bacterial infection in human gingiva. Human gingival samples were collected from periodontitis patients and transplanted in nu/nu mouse subdermis. After 2 weeks, human characteristics were confirmed by positive immunohistochemical reactions for human-specific markers. We used this model to investigate human β-defensin-2 (hBD-2), an antimicrobial peptide that contributes to initial defense against bacterial invasion. Using real-time polymerase chain reaction, in situ hybridization, and immunohistochemistry, we investigated whether hBD-2 expression was induced in human gingiva as a response to Porphyromonas gingivalis as a periodontal pathogen. Two hours after infection with bacteria, we detected increased expression of hBD-2 mRNA, which was localized in the epithelium of human gingiva. Using our in vivo model, we concluded that increased hBD-2 may play an important role in early defense from bacterial infection in human gingival epithelium.

The Salivary IgA Flow Rate Is Increased by High Concentrations of Short-Chain Fatty Acids in the Cecum of Rats Ingesting Fructooligosaccharides

Salivary immunoglobulin A (IgA) serves as a major effector in mucosal immunity by preventing submucosal invasion of pathogens. However, the mechanism by which consumption of fermentable fibers increases IgA in saliva was not fully elucidated. This study investigated the effects of fructooligosaccharides (FOS) intake and time after feeding on IgA levels in the saliva and cecal digesta and on the concentration of short-chain fatty acids (SCFA) in the cecum in rats. Five-week-old rats were fed a fiber-free diet or a diet with 50 g/kg FOS for zero, one, four, and eight weeks. Ingestion of FOS at one and eight weeks led to a higher IgA flow rate of saliva per weight of submandibular gland tissue (p < 0.05), which positively correlated with the concentration of SCFA in the cecal digesta (rs = 0.86, p = 0.0006, n = 12), but showed no correlation with the concentration of IgA in the cecal digesta (rs = 0.15, p = 0.3, n = 48). These results suggested that ingestion of FOS increased salivary IgA secretion through high levels of SCFA in the large intestine, which was produced by fermentation of FOS. Thus, continuously ingesting FOS for more than one week could increase secretion of salivary IgA.

Salivary lactoferrin is transferred into the brain via the sublingual route

Lactoferrin (LF) is produced by exocrine glands including salivary gland, and has various functions including infection defense. However, the transfer of LF from peripheral organs into the brain remains unclear. To clarify the kinetics of salivary LF (sLF), we investigated the consequences of sialoadenectomy and bovine LF (bLF) sublingual administration in rats. The salivary glands were removed from male Wistar rats, and we measured rat LF levels in the blood and brain at 1 week post-surgery. We also examined the transfer of LF into the organs of the rats after sublingual administration of bLF. Rat LF levels in the blood and brain were significantly reduced by sialoadenectomy. Sublingual bLF administration significantly increased bLF levels in the brain, which then decreased over time. These results indicate that LF is transferred from the sublingual mucosa to the brain, in which favorable effects of sLF on brain will be expected via the sublingual mucosa. Graphical abstract LF levels in the brain significantly decreased by sialoadenectomy (A). LF was also transferred from the sublingual mucosa to the brain (B).

Continuous combined intake of polydextrose and lactitol stimulates cecal fermentation and salivary IgA secretion in rats

Immunoglobulin A (IgA), which plays an important role in infection defense, is upregulated in the large intestine and oral cavity through dietary fiber intake. However, the mechanism underlying salivary IgA increase through dietary fiber intake remains unknown. This study investigated time-dependent effects of non-absorbable polydextrose (PDX) and lactitol intake on salivary IgA secretion and cecal fermentation. Five-week-old rats were fed a fiber-free diet with or without 25 g/kg PDX and 25 g/kg lactitol for 1, 4, and 8 weeks. Compared to control, those who ingested PDX and lactitol had higher salivary IgA flow rates per weight of submandibular gland tissue at 4 and 8 weeks (P < 0.05), greater cecal weight and digesta at 1, 4, and 8 weeks (P < 0.05), and lower concentrations of short chain fatty acids (SCFAs) in cecal digesta (P = 0.0003). These findings suggest that the consumption of PDX and lactitol may upregulate salivary IgA secretion possibly by stimulating absorption of SCFAs produced by cecal fermentation. Thus, continuous ingestion of PDX and lactitol for up to 4 weeks could increase salivary IgA and promote immune defense against pathogen invasion through the oral route.

Features of occlusal state in female Japanese patients with migraine: a case-controlled study

Objectives: The prevalence rate of migraines is 8.4%; it is mostly diagnosed in women at 20s to 40s, and is known to cause major physical and mental disruption to daily life. This study was conducted on women aged between their 20s and 40s, in order to investigate the possible differences in the features of the occlusal state between a migraine and a non-migraine (control) group. Methods: Age-matched female patients with migraine (n = 60) diagnosed by headache specialists and healthy controls (n = 57) were enrolled. Dental casts were used to evaluate some features. Results: The maxillary and mandibular dentition casts from the migraine group showed significantly characteristic findings in their Angle’s classification, overjet, and deviation in the anterior tooth midline, compared to the control group. Discussion: The results relating occlusal state to both tension-related headaches and migraines, which have different pathogeneses, suggest the possibility of dental intervention to improve the symptoms of primary headaches.

Grinding patterns in migraine patients with sleep bruxism: a case-controlled study

Objectives: Details on grinding patterns and types of contact during sleep bruxism in association with migraine headache have not yet been elucidated. This study compared the characteristics of sleep bruxism between patients with migraine and controls. Methods: The study included 80 female patients who had been diagnosed with migraine and 52 women with no history of migraine. Grinding patterns were measured using the BruxChecker® (Scheu Dental, Iserlohn, Germany). Results: There was a significant difference between the two groups in the distribution of grinding patterns at the laterotrusive side (p < 0.001). When the anterior teeth and premolar and molar regions in the two groups were compared, the proportion of the grinding area at all sites was significantly larger in the migraine group than in the control group (p < 0.001). Discussion: The BruxChecker® showed that there was substantial grinding over a large area among migraine patients, particularly in the molar region.