Tokyo Dental College

Animal studies suggest that periodontopathic bacteria induce gut dysbiosis and related pathology, possibly connecting periodontitis to non-oral diseases. However, the effects on the gut ecosystem in periodontitis patients are not fully understood.

We conducted a comprehensive analysis of the salivary and gut microbiota using 16S rRNA sequencing in periodontitis patients before and after treatment, comparing them to healthy participants. Serum metabolites were also analyzed.

Periodontitis patients showed high alpha diversity in both salivary and gut microbiota with a strong correlation. Significant differences were also observed in the gut microbiota composition between patients before treatment and healthy participants, irrespective of the ectopic colonization of periodontitis-associated bacteria in the gut. Co-abundance group analysis demonstrated that the gut microbiota of healthy participants was enriched with short-chain fatty acid producers. Changes in the gut microbiota coincided with alterations in the serum metabolite profile. While periodontal therapy improved salivary microbiota, it did not significantly affect gut microbiota.

Gut dysbiosis of periodontitis patients may impact systemic metabolite profiles. Given that periodontal therapy alone did not substantially improve the gut microbiota, adjunctive strategies targeting the gut microbiome may be effective in reducing the risk of periodontitis-associated diseases.

Macrophages and interdigitating dendritic cells (DCs) are key professional antigen-presenting cells. However, DCs appear to be absent in healthy nasal mucosa, despite the extensive ciliated respiratory epithelium being highly exposed to various antigens.

Using histological specimens from 20 elderly cadavers, we examined the distribution of immunoreactive cells in the nasal vestibular skin, mucocutaneous junction, and ciliated mucosa. CD1a, CD83 and DC-SIGN were used as DC markers, with the latter two being typically employed in lymphatic tissue studies.

Macrophages and CD8-positive lymphocytes were widely distributed throughout the subcutaneous and submucosal tissues at all epithelial depths. These cells were occasionally found embedded within both the mucocutaneous junction epithelium and basal layer of the mucosal epithelium. In contrast, CD4-positive lymphocytes were scarce across all examined sites. CD169-positive macrophages, considered the first-line gatekeepers in lymphatic tissues, were localized along deep vessels and glands. CD1a-positive DCs (Langerhans cells) were absent from both the cytokeratin 14-negative squamous epithelium and ciliary epithelium but were abundant in the basal layer of the cytokeratin 14-positive stratified squamous epithelium. CD1a-positive cells, which exhibit either a dendritic or round morphology, were occasionally scattered through the elastic fiber-rich subcutaneous tissue. A few DC-SIGN- or CD83-positive DCs were seen in glands and along deep vessels in subcutaneous and submucosal tissues CONCLUSION: Hair follicles at the nasal vestibule were likely accompanied by a cluster of CD1a-positive cells and CD8-positive lymphocytes. Macrophages, rather than DCs, were likely the primary antigen-presenting cells for CD8-positive lymphocytes in aged nasal respiratory mucosa.