Molecular Oral Microbiology最新文献

Introduction: The regulatory mechanisms of epithelial-mesenchymal transition (EMT) involved in periodontitis pathogenesis are poorly understood. Consequently, this study aimed to investigate the association of the long noncoding (lnc) RNAs, NEAT1 and MALAT1, with EMT in periodontitis.

Methods: Gingival tissue samples (n = 57) were obtained from periodontitis patients indicated for surgical treatment and healthy control individuals. Full mouth periodontal charting was recorded for all patients together with collection of subgingival biofilm samples to determine bacterial load for key-periodontal pathogens. Histopathological analysis was used to assess inflammatory cell infiltration, and RT-qPCR analysis was performed to quantify the expression of the key EMT biomarkers of E-cadherin, β-catenin, Snail1 and vimentin, and the lncRNAs of Neat1 and Malat1.

Results: The clinical parameters and percentage of inflammatory cell infiltration were significantly higher in the periodontitis group compared with healthy controls. In periodontitis, expressions of Malat1 and E-cadherin were significantly downregulated, whereas Neat1, Snail1 and vimentin were significantly upregulated in comparison to controls. Receiver-operating characteristic (ROC) analyses demonstrated moderate-to-good diagnostic accuracy of Neat1, Malat1, Snail1, E-cadherin and vimentin (area under the curve [AUC]: 70.3%, 67.5%, 78.7%, 89.9% and 74.3%, respectively) to discriminate periodontal health from disease.

Conclusion: Probing pocket depth, bleeding scores, expression of Neat1, red complex bacteria (Porphyromonas gingivalis and Treponema denticola) and downregulation of Malat1 and E-cadherin were strongly associated with EMT. Data also highlighted an association between Neat1 and Malat1 with the induction of the EMT phenotype in periodontitis, and these lncRNAs may therefore provide novel diagnostic biomarkers.

Objectives: Periodontal disease, a global health concern, is strongly associated with oral treponemes. However, the taxonomy of some species remains unresolved, hindering our understanding of their roles in disease. This study aims to clarify the taxonomy of three strains isolated from patients with periodontal disease using phylogenomic and comparative genomic analyses.

Materials and methods: We performed genome sequencing for OMZ 800 and conducted phylogenomic and comparative genomic analyses of multiple strains to clarify their taxonomy.

Results: Phylogenomic and in-silico genome comparisons confirmed OMZ 800 as "T. vincentii" (Average Nucleotide Identity [ANI]>95%). We designated OMZ 800^T as the type strain for T. vincentii to establish its official standing in bacterial taxonomy. OMZ 806 (2.7 Mb, 44.9% GC) clustered with phylogroup IB strain (ANI>95% vs. OMZ 305), whereas OMZ 838 (2.7 Mb, 44.6% GC) clustered with phylogroup IA strains (ANI>95% vs. OMZ 855 and OMZ 857). Both OMZ 806 and OMZ 838 strains showed ANI<95% compared to T. medium ATCC700293^T, supporting their classification as novel species. We propose Treponema plautii sp. nov. OMZ 806^T (with OMZ305 as additional strain) and Treponema sinense sp. nov. OMZ 838^T (with OMZ 855 and OMZ 857 as additional strains).

Conclusion: This study clarifies Treponema taxonomy by designating OMZ 800^T as the type strain of T. vincentii and proposing two novel species, providing a refined taxonomical framework for this important genus.

Microbial infections and lipopolysaccharide (LPS)-induced senescence in human dental pulp cells (hDPCs) play a significant role in gingivitis etiology. However, the role of Apelin-12 in oral diseases, particularly its modulation of cellular senescence, remains poorly understood. This study investigated the protective effects of Apelin-12 against LPS-induced cellular senescence in hDPCs and its underlying mechanisms using cell isolation, culture, treatment, and transduction techniques, combined with reverse transcription-polymerase chain reaction (RT-PCR), Western blotting, telomerase activity assays, senescence-associated β-galactosidase (SA-β-Gal) staining, and gene silencing. We first confirmed apelin receptor (APJ) expression in hDPCs and found that LPS significantly downregulated APJ at both mRNA and protein levels. Apelin-12 treatment restored telomerase activity and upregulated human telomerase reverse transcriptase (hTERT), while reducing senescence markers, including γH2AX and SA-β-Gal. Additionally, Apelin-12 suppressed the expression of senescence regulators p21 and acetylated p53 (ac-p53). Mechanistically, Apelin-12 restored SIRT6 (but not SIRT1) expression, and silencing SIRT6 abolished its anti-senescence effects, as evidenced by elevated p21, ac-p53, and SA-β-Gal, along with reduced hTERT and telomerase activity. These findings demonstrate that Apelin-12 attenuates LPS-induced cellular senescence in hDPCs via SIRT6-mediated pathways, suggesting its therapeutic potential for gingivitis management.

Socransky's complexes have identified a range of bacteria as key contributors to the onset and progression of periodontal disease. However, advancements in microbiological detection methods have allowed for exploration of the microbiome in periodontal health/disease in greater detail. In recent years, Filifactor alocis has emerged as a potential periodontal pathogen. Therefore, the aim of this review was to investigate whether this bacterium could be included in Socransky's model by summarizing the available evidence. A comprehensive literature search performed using PubMed, ScienceDirect, and Scopus databases was undertaken. The retrieved articles were filtered according to defined eligibility criteria, which yielded 24 studies. Data were extracted from these observational and clinical studies to synthesize findings. Findings regarding the host immune response were derived from in vitro and experimental animal models and narratively summarized. Observational studies and clinical trials showed heterogeneity and a lack of standardized outcomes. However, the general trend indicated a higher prevalence of F. alocis at diseased sites than at healthy sites. In addition, periodontal treatment was found to significantly reduce F. alocis levels and was associated with improvements in clinical periodontal parameters. Experimental models and in vitro studies showed that F. alocis exhibits a range of virulence attributes and pathogenic behavior similar to that of putative pathogenic periodontal bacteria. The evidence is not sufficient to include F. alocis as a new member of Socransky's model. However, this review suggests that this bacterium has the potential to be included in Socransky's complexes in the future after further research which would require to be highly standardized to enhance comparability and generalizability of findings.

Selenomonas sputigena is an understudied oral pathobiont associated with periodontitis and dental caries. We recently demonstrated that S. sputigena binds to gingival epithelial cells (GECs), where afterwards the bacterium causes robust in vitro pro-inflammatory cytokine production and migration of monocytes and neutrophils. Here, we report that extracellular adherent S. sputigena are subsequently internalized by GECs. Fluorescently labeled intracellular S. sputigena were observed in two gingival keratinocyte cell lines and primary cells. Oxygen-killed S. sputigena was found within GECs at a similar rate to living bacteria, suggesting active protein synthesis is not required for internalization. Host-cell actin polymerization was essential for the internalization of S. sputigena. Electron microscopy revealed that intracellular S. sputigena is located within a single membrane vesicle tightly wrapped around the bacterium which is decorated with LAMP1, indicating that S. sputigena is ultimately trafficked to a lysosome-like vesicle. Although S. sputigena mRNA was detectable within GECs, it rapidly decreased by 24 h post-inoculation. This differed from bacterial morphology, which remained intact up to 48 h. Induction of CXCL8 expression was concurrent with intracellular S. sputigena morphological integrity, suggesting that, while the bacteria are likely dead, bacterial macromolecules perpetuate inflammation in GECs. Collectively, this study demonstrates S. sputigena can be taken into gingival keratinocytes, where the bacterium induces inflammatory responses, but S. sputigena is ultimately processed by lysosomal machinery and is cleared from the intracellular niche in GECs.

Oral infectious diseases, particularly inflammatory periodontal lesions, exert a substantial impact on healthcare systems and economies, as acknowledged by the World Health Organization. The prevailing consensus attributes the onset of oral infectious diseases to dysbiosis within the intricate oral microbiome. In this context, Fretibacterium-a strictly anaerobic genus whose representative species, Fretibacterium fastidiosum, was classified in 2013 as the third human oral species within the Synergistetes phylum-has garnered attention for its progressive enrichment in periodontitis and distinct abundance profiles in health versus disease. This review synthesizes current knowledge on Fretibacterium's role in periodontal disease, dental caries, endodontic infections, and peri-implantitis, with emphasis on its virulence mechanisms. Then further explore its clinical associations with systemic conditions (e.g., diabetes) and evaluate conventional and emerging therapeutic strategies. By providing evidence-based insights, this work aims to guide clinical management and future research directions.

Tyrosine phosphorylation/dephosphorylation post-translational modification (PTM) of proteins in bacteria can control their function and location. PTM of transcriptional regulators and DNA-binding proteins, as well as components of their signaling pathways, can impact gene expression. However, little is known regarding the global impact of tyrosine phosphatases on the bacterial transcriptome. In this study, we performed RNA-Seq of Porphyromonas gingivalis wild type (WT) along with strains Δltp1 and Δphp1 with mutations in the genes encoding the two major tyrosine phosphatases, Ltp1 and Php1, respectively. Moreover, these strains were tested in vitro and in vivo (mouse abscess) conditions. Both the Δltp1 and the Δphp1 mutants exhibited little transcriptional difference to the parental strain when cultured in vitro. In vivo, comparison of the Δphp1 mutant to the WT showed a number of differentially regulated genes (DEGs) associated with transporter systems. In vivo DEGs in Δltp1 included one of the efflux ABC transporter systems also regulated in the Δphp1 mutant; however, the primary biological process populated by DEGs in Δltp1 involved genome stability. Comparison of the WT strain between the in vitro and in vivo condition indicated that DNA metabolic processes, including recombination and transposition, were significantly upregulated in vivo. Hence, a major role of Ltp1 phosphatase activity at the transcriptional level may be control of adaptation to in vivo conditions. Additionally, both Ltp1 and Php1 have common functions in the control of the expression of genes encoding transporter systems.

The collagen-binding adhesin Cnm is a known virulence factor of Streptococcus mutans. It is present in specific serotypes (mostly e, f, and k strains) of S. mutans and belongs to the LPXTG family of cell wall-anchored surface adhesins. Here, we report the crystal structure of the collagen-binding N₂ domain of S. mutans Cnm. Using the Staphylococcus aureus collagen-binding protein Cna, which shares high sequence and structural homology with Cnm, we modeled collagen binding to S. mutans Cnm. The comparative analysis identified three conserved collagen-binding residues (Y176, F192, N194) and four equivalent residues that are different in their composition (D224, T226, S232, M276). This study also discovered the multifunctional attributes of this protein, where Cnm-FL, Cnm-N_12, and the individual domains of Cnm-N₁ and Cnm-N₂ adhere with high affinity to the scavenger receptor cysteine-rich (SRCR) domains of glycoprotein 340 (Gp340). Protein-protein docking of Cnm-N₂ and SRCR₁ showed the possibility of a shared binding site at the collagen-binding interface of Cnm-N₂. Furthermore, competition experiments using collagen and SRCR₁₂₃ with Cnm-N₂, Cnm-N_12, and Cnm-FL constructs confirmed that collagen and SRCR₁ share a binding site. Subsequent alanine substitution mutagenesis of the predicted collagen-binding residues validated our modeling results, confirming that Y176 and F192 are important residues for collagen and SRCR/Gp340 binding.

Lysine succinylation (Ksuc) is a novel post-translational modification (PTM), which regulates biological functions in bacteria. Streptococcus mutans has been identified as a predominant cariogenic pathogen responsible for the initiation and progression of dental caries. However, lysine succinylation in S. mutans has not yet been investigated. In this study, a global lysine succinylome was analyzed to examine Ksuc in S. mutans. Overall, 2250 succinylated sites in 580 proteins were identified. Quantitative analysis demonstrated that Ksuc substrates were substantially altered in the biofilm growth state compared with the planktonic growth state. These differentially succinylated proteins were distributed across various cellular components and involved in crucial biological pathways, including translation, ribosomal structure, and biogenesis. Furthermore, lysine acetylation and succinylation extensively overlapped in S. mutans, and these bimodified proteins were associated with biofilm formation, glycolysis, and pyruvate metabolism. These results provided a foundation to further investigate the role of Ksuc in S. mutans pathogenicity and expand our understanding of Ksuc functions in bacterial physiology and virulence.

Streptococcus mutans is considered the main pathogen causing dental caries and has a strong ability to establish biofilms and respond to environmental stimuli, which are essential for its survival and cariogenicity. Fourteen two-component signal transduction systems (TCSs) in S. mutans have been reported to regulate a broad range of physiological processes such as bacterial biofilm formation, acid resistance, competence development, and toxic oxygen metabolite resistance. These systems collectively contribute to the cariogenicity of S. mutans by coordinating adaptive responses to environmental challenges. Among them, the VicRK system has been one of the most extensively studied, with epidemiological evidence linking vicK mutations to increased caries risk in children. Other TCSs, such as ComDE, LiaRS, CiaRH, and the orphan response regulator GcrR, also contribute to cariogenicity regulation. The present review summarizes the regulatory roles of TCSs in virulence traits of S. mutans, with an emphasis on those involved in biofilm formation, which highlights their potential as therapeutic targets to prevent dental caries through biofilm inhibition.