Direct and Indirect Effects of IL-17A on RANKL-Induced Osteoclastogenesis

Synthesis of Theaflavins and Their Functions

Numerous epidemiological and interventional clinical studies have consistently reported that black tea is good for human health. The polyphenolic compound, theaflavin, and its galloyl esters (theaflavins) are the primary red pigments in black tea that possess several health benefits, including fat-reducing and glucose-lowering capabilities and lifestyle-related disease prevention related to anti-obesity, anticancer, anti-atherosclerotic, anti-inflammatory, antiviral, antibacterial, anti-osteoporotic, and anti-dental caries properties. These compounds are produced by key enzymes, such as polyphenol oxidase and peroxidase, from parent green tea catechins present in fresh green tea leaves during the production of black tea leaves or the fermentation of green tea. However, theaflavins are only present in low concentrations in black tea; thus, their extraction from black tea leaves at sufficient levels for use in medical studies has been difficult. To circumvent this issue, different procedures for the synthesis of theaflavins using chemical oxidizing reagents or enzymes have been studied; however, low yields have limited their utility. Recently, however, several biosynthetic methods have been developed for the mass production of theaflavins. Using these methods, the physiological functions of theaflavins in lifestyle-related diseases in mice and humans have also been studied. In this review, we present the synthesis of theaflavins and their health benefits.

Association Between the Duration of Periodontitis and Increased Cardiometabolic Risk Factors: A 9-Year Cohort Study

BACKGROUND

Epidemiological studies have reported that periodontitis and cardiometabolic disease such as cardiovascular disease and type 2 diabetes are associated; however, there have been very few prospective cohort studies on this topic. Therefore, we conducted a 9-year follow-up study to examine the relationship between the duration of periodontitis and cardiometabolic risk factors, including hypertension, hyperglycemia, dyslipidemia, and obesity.

METHODS

The study participants comprised 572 adult industrial workers (417 men and 155 women; mean age, 37.4 years) who had undergone annual medical and dental health examinations from 2003 to 2012; the evaluation of the four cardiometabolic risk factors in 2003 revealed normal values in all the participants. We investigated the relationship between the cumulative duration of the presence of periodontal pockets, which is a major symptom of periodontitis, and the presence of cardiometabolic risk factors after 9 years using multiple logistic regression analysis.

RESULTS

The odds ratio (OR) for the presence of ≥1 cardiometabolic risk factor in participants with a cumulative duration of periodontal pockets for ≥6 years was significantly higher than that in participants without pockets. The ORs for the onset of obesity, hypertension, dyslipidemia, and hyperglycemia were higher in participants with a cumulative duration of periodontal pockets for ≥6 years than those in participants without pockets or in participants with a cumulative duration of periodontal pockets for ≤5 years, and all the differences, except dyslipidemia, were significant.

CONCLUSIONS

Chronic periodontitis was significantly associated with having cardiometabolic risk factors during the 9-year observation period, suggesting that the risk of cardiometabolic disease might increase in people who have untreated periodontitis.

Tension force-induced ATP promotes osteogenesis through P2X7 receptor in osteoblasts

Orthodontic tooth movement induces alveolar bone resorption and formation by mechanical stimuli. Force exerted on the traction side promotes bone formation. Adenosine triphosphate (ATP) is one of the key mediators that respond to bone cells by mechanical stimuli. However, the effect of tension force (TF)-induced ATP on osteogenesis is inadequately understood. Accordingly, we investigated the effect of TF on ATP production and osteogenesis in MC3T3-E1 cells. Cells were incubated in the presence or absence of P2X7 receptor antagonist A438079, and then stimulated with or without cyclic TF (6% or 18%) for a maximum of 24 h using Flexercell Strain Unit 3000. TF significantly increased extracellular ATP release compared to control. Six percent TF had maximum effect on ATP release compared to 18% TF and control. Six percent TF induced the expression of Runx2 and Osterix. Six percent TF also increased the expression of extracellular matrix proteins (ECMPs), ALP activity, and the calcium content in ECM. A438079 blocked the stimulatory effect of 6% TF on the expression of Runx2, Osterix and ECMPs, ALP activity, and calcium content in ECM. This study indicated that TF-induced extracellular ATP is released in osteoblasts, suggesting that TF-induced ATP promotes osteogenesis by autocrine action through P2X7 receptor in osteoblasts. J. Cell. Biochem. 116: 12–21, 2015. © 2014 The Authors. Journal of Cellular Biochemistry published by Wiley Periodicals, Inc.

Intragingival injection of Porphyromonas gingivalis-derived lipopolysaccharide induces a transient increase in gingival tumour necrosis factor-α, but not interleukin-6, in anaesthetised rats

This study used in vivo microdialysis to examine the effects of intragingival application of lipopolysaccharide (LPS) derived from Porphyromonas gingivalis (Pg-LPS) on gingival tumour necrosis factor (TNF)-α and interleukin (IL)-6 levels in rats. A microdialysis probe with an injection needle attached to the surface of the dialysis membrane was implanted into the gingiva of the upper incisor. For comparison, the effects of LPS derived from Escherichia coli (Ec-LPS) on IL-6 and TNF-α levels were also analysed. Pg-LPS (1 μg/1 μL) or Ec-LPS (1 or 6 μg/1 μL) was applied by microsyringe, with gingival dialysates collected every hour. Enzyme-linked immunosorbent assay (ELISA) revealed that gingival dialysates contained approximately 389 pg·mL⁻¹ of IL-6 basally; basal TNF-α levels were lower than the detection limit of the ELISA. Pg-LPS failed to alter IL-6 levels but markedly increased TNF-α levels, which remained elevated for 2 h after treatment. Neither IL-6 nor TNF-α were affected by Ec-LPS. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis revealed that the gingiva expresses Toll-like receptor (TLR) 2 and TLR4 mRNA. Immunohistochemical examination showed that TLR2 and TLR4 are expressed by gingival epithelial cells. The present study provides in vivo evidence that locally applied Pg-LPS, but not Ec-LPS, into the gingiva transiently increases gingival TNF-α without affecting IL-6. The present results suggest that TLR2 but not TLR4 expressed on gingival epithelial cells may mediate the Pg-LPS-induced increase in gingival TNF-α in rats.

Serum γ-glutamyltransferase level is associated with periodontal disease independent of drinking habits in Japanese adults

Background Non-alcoholic fatty liver disease is considered a hepatic manifestation of metabolic syndrome. Periodontal disease is a mild chronic inflammatory disease with systemic effects, and many studies have indicated an association between metabolic syndrome and periodontitis. In the present study, we investigated the relationship between periodontitis and liver biochemical parameters according to alcohol drinking habits through a cross-sectional study based on data from Japanese people in occupational settings. Material and Methods The subjects were 1510 employees (1218 males, 292 females, mean age 50.4 years) who underwent dental and medical checkups in 2012. Associations between the presence of periodontal pockets and serum levels of liver biochemical parameters were assessed. Results Alanine aminotransferase (ALT) and γ-glutamyltransferase (GGT) levels were higher in subjects with than without periodontal pockets. Multiple logistic regression analysis (adjusting for age, gender, cigarette smoking, and alcohol drinking habits, and components of metabolic syndrome) with GGT or ALT as the dependent variable revealed that there was a significant association between periodontal pockets and GGT (odds ratio, OR=1.48), but not ALT. Similar associations were observed when an analysis was performed according to the presence or absence of alcohol drinking habits; the OR was higher in subjects without (OR=1.84) than with drinking habits (OR=1.41). Conclusions The presence of periodontal pockets was associated with serum levels of GGT, a liver biochemical parameter, in Japanese adults with no drinking habit, suggesting that periodontal disease is associated with liver function, independent of alcohol ingestion.