Molecular Oral Microbiology最新文献

Over the years, humanity has accumulated knowledge about the pathogens of infectious diseases and the ability of the human body to resist external aggression. In the last century, it became clear that the normal microflora of the human body can be used as an ally to resist a whole range of diseases. However, the intestinal microflora is the main object of modern complex studies. This review focuses on the microflora of the oral cavity. It describes the main microbiological composition of the microflora, including the most important bacterial species, fungi, and viruses. The main factors influencing the emergence of balance in the system "human oral cavity-microorganisms" are considered as well as environmental features that affect the formation of the species composition. The main functions performed by the oral microflora are described. Possible mechanisms for correcting initial dysbiotic disorders are also considered, including probiotics, bacteriophages, gases and thermotherapy, photobiomodulation, and diet correction.

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.

Treponema denticola is a Gram-negative, anaerobic spirochete associated with periodontal disease. It navigates highly viscous environments using periplasmic flagella located between the inner and outer membranes. The flagellum is composed of three homologous flagellin proteins-FlaB1, FlaB2, and FlaB3-encoded by the flaB1, flaB2, and flaB3 genes, respectively, and is enwrapped by the sheath protein FlaA, encoded by the flaA gene. To investigate the roles of the three FlaB flagellins in cell morphology and motility, we constructed mutants lacking different combinations of the flaB genes, including double and triple deletions. The deletion of one or two flaB genes did not affect the transcription or protein expression of the remaining flaB gene(s). Normal flagellar filaments were observed when at least one FlaB was expressed but were absent in the complete flaB deletion mutant, which also exhibited an elongated cell shape. The flagella had no significant impact on bacterial growth. In liquid medium, most mutants exhibited rotational movement comparable to the parent strain, although some showed an increased population of cells with higher rotation rates. However, in a medium containing 0.5% agar, deletion of any two or three flaB genes significantly reduced motility. These findings suggest that the expression of at least two FlaB flagellins is required for the potent movement of T. denticola.

As first responders, neutrophils are a vital component of the host defense against oral pathogens, and their function is critical in preventing the progression of periodontal diseases. Streptococcus gordonii, a generally commensal oral bacterium, has been implicated in the pathogenesis of diseases by operating as a pathobiont with Porphyromonas gingivalis in periodontitis, and as an independent pathogen in infective endocarditis. Although the pathogenicity of S. gordonii is variable, its role in modulating, as well as responding to, host neutrophils remain, poorly understood. This study focuses on neutrophil activation, migration, and bactericidal activity towards S. gordonii. Our results found S. gordonii induced significant upregulation of surface markers CD63 and CD66 on neutrophils, a phenotypic change reminiscent of an oral neutrophil, and was enhanced by pre-activation of neutrophils by lipopolysaccharide (LPS) or the oral pathogen P. gingivalis. Co-incubations with P. gingivalis also led to a decreased ability of neutrophils to kill the normally commensal S. gordonii, though not other commensals with opportunistic pathogen potential, including Escherichia coli or Staphylococcus aureus. This increase in survival correlated with changes in phagosomal maturation, a decrease in cytoplasmic and phagosomal-associated granules, and increased IL-1β production. These results suggest oral streptococci may significantly contribute to oral neutrophil phenotypes associated with health, but introduction of oral pathogens can exacerbate a neutrophil shift and contribute to the persistence of S. gordonii, and its ability to contribute to the pathogenesis of periodontal disease.

Periodontal bacterial pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs) accelerate inflammatory osteoclastogenesis, resulting in alveolar bone loss. The core PAMP and DAMP prototype molecules are periodontal bacterium Porphyromonas gingivalis-derived virulence lipids, for example, phosphoglycerol dihydroceramide (PGDHC) and lipopolysaccharide (LPS Pg), and the host non-histone alarmin high mobility group box protein-1 (HMGB1), respectively. Although it was reported that extracellularly released HMGB1 is critical for the promotion of sepsis inflammation in response to non-periodontal bacterial LPS, our understanding of the crosstalk between HMGB1 and P. gingivalis-derived virulence lipids remains limited. Therefore, we used Hmgb1^fl/fl LysM-Cre⁺ mice with ablated HMGB1 mRNA and littermate Hmgb1^fl/fl LysM-Cre^- controls. We observed limited Hmgb1^fl/fl LysM-Cre⁺ osteoclastogenesis compared to Hmgb1^fl/fl in response to RANKL in vitro. Furthermore, recombinant HMGB1 protein restored osteoclast formation in Hmgb1^fl/fl LysM-Cre⁺ cells, indicating the pivotal role of extracellular HMGB1 in osteoclastogenesis in vitro. Using bulk RNA-sequencing, we identified the diminished osteoclastogenesis in Hmgb1^fl/fl LysM-Cre⁺ cells are linked to accelerated expression of canonical osteoclast-suppressing interferon genes. We surprisingly detected that PGDHC and LPS Pg accelerate osteoclastogenesis in Hmgb1^fl/fl LysM-Cre⁺ cells in vitro. Using bulk RNA-sequencing and real-time PCR assays, we confirmed that PGDHC diminishes the expression patterns of different interferon-inducible guanylate-binding proteins (GBP 3, 4, 5, 9). At the same time, LPS Pg accelerates the expression of osteoclast-promoting matrix metalloproteases (MMP 8 and 12) mRNAs. The results suggest that the RANKL-primed osteoclastogenesis accelerated by P. gingivalis-derived virulence lipids is mediated by different MMP or GBP signaling pathways independently from canonical HMGB1 signaling.

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.