Correlation of Redondovirus and Entamoeba gingivalis Detections in the Human Oral Cavity Suggests That This Amoeba Is Possibly the Redondovirus Host.

The virome of the human oral cavity and the relationships between viruses and diseases such as periodontitis are scarcely deciphered. Redondoviruses were reported in the human oral cavity in 2019, including in periodontitis patients. Here, we aimed at detecting redondoviruses and at searching for a potential viral host in human saliva. Non-stimulated saliva was collected between December 2020 and June 2021. These samples were tested using real-time PCR regarding the presence of redondovirus and Entamoeba gingivalis DNA. Similarity searches were performed using BLAST against eukaryotic and prokaryotic sequences from GenBank. The redondovirus DNA was detected in 46% of the 28 human saliva samples. In addition, short fragments of redondovirus genomes were detected in silico within Entamoeba sequences. Finally, Entamoeba gingivalis DNA was detected in 46% of the 28 saliva samples, with a strong correlation between redondovirus DNA and E. gingivalis DNA detections, in 93% of the cases. Regarded together, these findings and previous ones strongly support the presence of redondoviruses in the human oral cavity and their association to E. gingivalis as their likely host.

Prognostic Role of Porphyromonas gingivalis Gingipain Rgp and Matrix Metalloproteinase 9 in Oropharyngeal Squamous Cell Carcinoma.

BACKGROUND/AIM: The oral bacteria involved in the development of periodontitis alter the tissue conditions and modify immune responses in a way that may also influence tumor development. We investigated the prevalence of R gingipain (Rgp), a key virulence factor of the oral pathobiont Porphyromonas gingivalis, and the tissue-destructive enzymes matrix metalloproteinase 8 (MMP-8) and 9 (MMP-9) in 202 unselected consecutive oropharyngeal squamous cell carcinoma (OPSCC) samples. We further investigated the relationships between these factors and human papillomavirus (HPV) status, Treponema denticola chymotrypsin-like proteinase (Td-CTLP) immunoexpression, clinical parameters, and patient outcome. PATIENTS AND METHODS: Clinicopathological data were derived from university hospital records. Rgp, MMP-8, and MMP-9 immunoexpression was evaluated by immunohistochemistry; the immunohistochemistry of Td-CTLP and HPV has been described earlier for this patient series. Cox regression analysis including death by causes other than OPSCC as a competing risk served to assess sub distribution hazard ratios. RESULTS: In multivariable survival analysis, positive tumoral MMP-9 immunoexpression predicted poor prognosis among all patients [sub distribution hazard ratio (SHR)=2.4; confidence interval (CI)=1.2-4.4, p=0.008], and especially among those with HPV-negative OPSCC (SHR=3.5; CI=1.7-7.3, p=0.001). Positive immunoexpression of Rgp in inflammatory cells was associated with favorable outcome among all patients (SHR=0.5, CI=0.2-0.9, p=0.021) and among those with HPV-negative disease (SHR=0.4, CI=0.2-0.9, p=0.022). CONCLUSION: Our results suggest that tumoral MMP-9 may be related to poor outcome in OPSCC, especially in HPV-negative disease, while Rgp immunoexpression in inflammatory cells is associated here with better disease-specific survival (DSS).

Volatile sulfide compounds and oral microorganisms on the inner surface of masks in individuals with halitosis during COVID-19 pandemic.

Mask-wearing is still recommended owing to the continuing impact of the COVID-19 pandemic. Within the closed chamber created by the mask, people are increasingly self-aware of their oral malodor. In this prospective and cross-sectional study, we aimed to measure volatile sulfide compound (VSC) levels in patients with halitosis and investigate the oral microbiome profile on the inner surface of their KF94 masks. We also investigated which oral microbiota increases VSC levels and whether the oral microbiomes of oral saliva and mask are correlated. A total of 50 subjects (41 women, average age 38.12 ± 12.58 years old) were included in the study, 25 healthy subjects and 25 patients with halitosis who wore masks for more than 3 h. The dominant bacterial species, bacterial profile, and Shannon diversity index of whole unstimulated saliva and the inner surface of the mask were investigated. The bacterial 16S ribosomal RNA genes of the major oral bacterial species were analyzed using real-time PCR. Gas chromatography was used to measure hydrogen sulfide (H2S) and methyl mercaptan (CH3SH), which are representative VSCs. The total bacterial DNA copy number was significantly higher in the saliva sample than in the mask sample (p < 0.001), and the average value was 276 times greater. Shannon diversity index was also significantly higher in saliva than in the inner surface of the mask (2.62 ± 0.81 vs. 1.15 ± 1.52, p < 0.001). The most common Gram-negative and Gram-positive species in the masks were Porphyromonas gingivalis (Pg) and Lactobacillus casei (Lc), respectively. The bacterial species with significant positive correlations between saliva and mask samples were Prevotella intermedia (Pi) (r = 0.324, p = 0.022), Eikenella corrodens (r = 0.309, p = 0.029), Lc (r = 0.293, p = 0.039), and Parvimonas micra (Pm) (r = 0.366, p = 0.009). The mean value of CH3SH was significantly higher in the halitosis group than in the non-halitosis group (17.84 ± 29.00 vs. 3.84 ± 10.57 ppb, p = 0.031). In the halitosis group, the DNA copy numbers and VSC levels showed highly positive correlation coefficients in the order Pg, Treponema denticola (Td), Tannerella forsythia (Tf), Pi, and Prevotella nigrescens (Pn) (all p < 0.05). Regarding bacterial profiles of the mask, Td was strongly correlated with CH3SH (r = 0.414, p = 0.040) and total VSCs (r = 0.374, p = 0.033) only in halitosis group. Mask-wearing time was strongly correlated with total VSCs, H2S, and CH3SH (all r > 0.8, p < 0.001). Oral bacteria, whose association with halitosis has been identified, increased VSC levels in mask-wearing subjects during the COVID-19 pandemic, particularly the number of Gram-negative anaerobes such as Pg and Td. Mask-wearing time was a major factor in increasing VSC levels. The study results suggest that people with halitosis could control these Gram-negative bacteria by improving oral hygiene and regularly changing masks.

Porphyromonas gingivalis Components/Secretions Synergistically Enhance Pneumonia Caused by Streptococcus pneumoniae in Mice.

Streptococcus pneumoniae is an important causative organism of respiratory tract infections. Although periodontal bacteria have been shown to influence respiratory infections such as aspiration pneumonia, the synergistic effect of S. pneumoniae and Porphyromonas gingivalis, a periodontopathic bacterium, on pneumococcal infections is unclear. To investigate whether P. gingivalis accelerates pneumococcal infections, we tested the effects of inoculating P. gingivalis culture supernatant (PgSup) into S. pneumoniae-infected mice. Mice were intratracheally injected with S. pneumoniae and PgSup to induce pneumonia, and lung histopathological sections and the absolute number and frequency of neutrophils and macrophages in the lung were analyzed. Proinflammatory cytokine/chemokine expression was examined by qPCR and ELISA. Inflammatory cell infiltration was observed in S. pneumoniae-infected mice and S. pnemoniae and PgSup mixed-infected mice, and mixed-infected mice showed more pronounced inflammation in lung. The ratios of monocytes/macrophages and neutrophils were not significantly different between the lungs of S. pneumoniae-infected mice and those of mixed-infected mice. PgSup synergistically increased TNF-α expression/production and IL-17 production compared with S. pneumoniae infection alone. We demonstrated that PgSup enhanced inflammation in pneumonia caused by S. pneumoniae, suggesting that virulence factors produced by P. gingivalis are involved in the exacerbation of respiratory tract infections such as aspiration pneumonia.

Altered expression of SARS-CoV-2 entry and processing genes by Porphyromonas gingivalis-derived lipopolysaccharide, inflammatory cytokines and prostaglandin E2 in human gingival fibroblasts.

OBJECTIVE: The aim of this in vitro study was to investigate the expression of SARS-CoV-2 entry and processing genes in human gingival fibroblasts (HGnF) following treatment with Porphyromonas gingivalis-derived lipopolysaccharide (PgLPS) or inflammatory cytokines/mediators. DESIGN: We assessed the expression of SARS-CoV-2 entry and processing genes; angiotensin-converting enzyme 2 (ACE2), cellular serine proteases transmembrane serine protease 2 (TMPRSS2), Furin, and basigin (BSG) in HGnF by real-time PCR. To further asses the contribution of PgLPS and inflammatory cytokines/mediators to proliferation and SARS-CoV-2 entry and processing gene expression, HGnF were treated with PgLPS, IL1ß, TNFα, and PGE2. RESULTS: The expression for ACE2 in HGnF was significantly elevated after PgLPS or IL1ß, TNFα, PGE2 treatment. The expression of TMPRSS2 was increased by PgLPS, IL1ß, or PGE2 while BSG was elevated by PgLPS and IL1ß. The expression of BSG and FURIN decreased after TNFα treatment. CONCLUSION: SARS-CoV-2 entry and processing genes are expressed in human gingival fibroblasts and their expressions are altered by PgLPS, IL1ß, TNFα and PGE2 treatment.