Effect of 5-aminolevulinic acid-mediated photodynamic therapy against Fusobacterium nucleatum in periodontitis prevention.

Periodontitis, a chronic infectious disease leading to gingival atrophy and potential tooth loss through alveolar bone resorption, is closely linked to the oral microbiome. Fusobacterium nucleatum, known to facilitate late-stage bacterial colonization in the oral microbiome, plays a crucial role in the onset of periodontitis. Controlling F. nucleatum abundance is vital for preventing and treating periodontal disease. Photodynamic therapy combined with 5-aminolevulinic acid (ALA-PDT) has been reported to be bactericidal against Pseudomonas aeruginosa and Staphylococcus aureus. We aimed to investigate the bactericidal potential of ALA-PDT against F. nucleatum, which was evaluated by examining the impact of varying 5-ALA concentrations, culture time, and light intensity. After ALA-PDT treatment, DNA was extracted from interdental plaque samples collected from 10 volunteers and sequenced using the Illumina MiSeq platform. To further elucidate the bactericidal mechanism of ALA-PDT, porphyrins were extracted from F. nucleatum following cultivation with 5-ALA and subsequently analyzed using fluorescence spectra. ALA-PDT showed a significant bactericidal effect against F. nucleatum. Its bactericidal activity demonstrated a positive correlation with culture time and light intensity. Microbiota analysis revealed no significant alteration in α-diversity within the ALA-PDT group, although there was a noteworthy reduction in the proportion of the genus Fusobacterium. Furthermore, fluorescence spectral analysis indicated that F. nucleatum produced an excitable photosensitive substance following the addition of 5-ALA. Overall, if further studies confirm these results, this combined therapy could be an effective strategy for reducing the prevalence of periodontitis.

TLR2-dependent and independent pyroptosis in dTHP-1 cells induced by Actinomyces oris MG-1.

In the immune system, the detection of pathogens through various mechanisms triggers immune responses. Several types of specific programmed cell deaths play a role in the inflammatory reaction. This study emphasizes the inflammatory response induced by Actinomycetes. Actinomyces spp. are resident bacteria in human oral plaque and often serve as a bridge for pathogenic bacteria, which lack affinity to the tooth surface, aiding their colonization of the plaque. We aim to investigate the potential role of Actinomyces oris in the early stages of oral diseases from a new perspective. Actinomyces oris MG-1 (A. oris) was chosen for this research. Differentiated THP-1 (dTHP-1) cells were transiently treated with A. oris to model the inflammatory reaction. Cell viability, as well as relative gene and protein expression levels of dTHP-1 cells, were assessed using CCK-8, quantitative real-time polymerase chain reaction (RT-qPCR), enzyme-linked immunosorbent assay (ELISA), and Western blot assay. The treatment decreased cell viability and increased the expression of inflammatory genes such as IL-1R1 and NLRP3. It was also observed to significantly enhance the release of IL-1ß/IL-18 into the supernatant. Immunoblot analysis revealed a notable increase in the expression of N-gasdermin D persisting up to 24 h. Conversely, in models pre-treated with TLR2 inhibitors, N-gasdermin D was detectable only 12 h post-treatment and absent at 24 h. These results suggest that Actinomyces oris MG-1 induces pyroptosis in dTHP-1 cells via TLR2, but the process is not solely dependent on TLR2.

Resveratrol is an inhibitory polyphenol of epithelial-mesenchymal transition induced by Fusobacterium nucleatum.

OBJECTIVE: Resveratrol is a natural phytoalexin that has anti-inflammatory properties, reverses doxorubicin resistance, and inhibits epithelial-mesenchymal transition (EMT) in many types of cancer cells. Fusobacterium nucleatum is reportedly enriched in oral squamous cell carcinoma (OSCC) tissues compared to adjacent normal tissues, sparking interest in the relationship between F. nucleatum and OSCC. Recently, F. nucleatum was shown to be associated with EMT in OSCC. In the present study, we aimed to investigate the effects of the natural plant compound resveratrol on F. nucleatum-induced EMT in OSCC. DESIGN: F. nucleatum was co-cultured with OSCC cells, with a multiplicity of infection (MOI) of 300:1. Resveratrol was used at a concentration of 10 µM. Cell Counting Kit-8 and wound healing assays were performed to examine the viability and migratory ability of OSCC cells. Subsequently, real-time RT-PCR was performed to investigate the gene expression of EMT-related markers. Western blotting and immunofluorescence analyses were used to further analyze the expression of the epithelial marker E-cadherin and the EMT transcription factor SNAI1. RESULTS: Co-cultivation with F. nucleatum did not significantly enhance cell viability. The co-cultured cells displayed similarities to the positive control of EMT, exhibiting enhanced migration and expression changes in EMT-related markers. SNAI1 was significantly upregulated, whereas E-cadherin, was significantly downregulated. Notably, resveratrol inhibited F. nucleatum-induced cell migration, decreasing the expression of SNAI1. CONCLUSIONS: Resveratrol inhibited F. nucleatum-induced EMT by downregulating SNAI1, which may provide a target for OSCC treatment.

Complete Genome Sequence of Actinomyces oris Strain K20, Isolated from an Oral Apical Lesion.

Actinomyces oris strain K20 was isolated from oral apical lesions. Here, we report the complete circular genome sequence of this strain, obtained by means of hybrid assembly using two next-generation sequencing datasets. The strain has a 3.1-Mb genome with 2,636 coding sequences.