Osamu Uehara

Objective and Background Heated tobacco products have recently become commercially available. These products, as well as combustible cigarettes, produce aerosols; the risk of various diseases associated with heated tobacco products may be the same or higher than that with combustible cigarettes. In this study, we examined the effect of Ploom TECH + extract on gingival epithelial cells. Methods Tobacco leaves from Ploom TECH + tobacco capsules and water were mixed and heated; the supernatant subsequently collected was the heated tobacco product (HTP; control: HTP not added). Normal human gingival epithelial progenitors were cultured alternately with or without HTP for a total of 1 month. Subsequently, RNA, DNA, and proteins were isolated from these samples and comprehensively analyzed using RNA sequencing (RNA‐seq), reduced representation bisulfite sequencing (RRBS), and western blotting, respectively. Results RNA‐seq revealed that 284 genes showed a twofold increase and 145 genes showed a twofold decrease in gene expression. A heat map showed genetic differences between the control and HTP groups. A principal component analysis plot showed a clear genetic distribution between the control and HTP. Gene Ontology (GO) analysis showed that genes related to seven GO terms, including cornification and keratinization, were induced by long‐term HTP stimulation. By contrast, GO pathways with a significant decrease in component expression were not detected. RRBS revealed that CpG island methylation increased more than twofold in 158 genes and decreased to less than twofold in 171 genes. Methylation of these CpG islands was not correlated with changes in gene expression levels. HTP treatment increased S100A7 expression. Conclusion Long‐term HTP stimulation affected epithelial differentiation and keratinization of gingival epithelial cells. Thus, habitual use of Ploom TECH + may be a risk factor for tobacco‐related oral mucosal diseases.

Background and Objective The translocation of oral bacteria, including Porphyromonas gingivalis , to the gut has been shown to alter gut microbiome. However, the effect of P. gingivalis on gut microbiome in relation to aging has not been demonstrated. We hypothesize that P. gingivalis has more detrimental effect on gut environment with increased age. The objective of this study is to investigate the effect of P. gingivalis on gut environment using aged mice. Materials and Methods C57BL/6J mice aged 4 weeks (young) or 76 weeks (old) were divided into four groups: control‐young, control‐old, P. gingivalis ‐administered young, and P. gingivalis ‐administered old. P. gingivalis was orally administered thrice weekly for 5 weeks. At 30 days after the last P. gingivalis administration, 16S rRNA sequencing was performed to study the gut microbiome. The mRNA and protein expression of intestinal junctional barrier molecules and the levels of the inflammatory cytokines IL‐1β and TNF‐α in the serum were evaluated. Results Significant differences in the gut microbiomes between the groups, in terms of taxonomic abundance, bacterial diversity, and predicted metagenome function, were observed. A significant reduction in the alpha diversity and in the abundance of beneficial bacteria, such as Akkermansia and Clostridiaceae, in the P. gingivalis ‐administered old mice was observed. The mRNA and protein levels of Claudin‐1 and Claudin‐2 in the intestine were significantly elevated, while E‐cadherin was significantly downregulated in the P. gingivalis ‐administered old mice, as were the serum levels of IL‐1β and TNF‐α. Conclusion The effect of P. gingivalis on the gut environment is more pronounced in old mice than in young mice.