Molecular Oral Microbiology最新文献

Introduction: COVID-19 is a transmissible respiratory and multisystem disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Viral transmission occurs mainly through the spread of salivary droplets or aerosol from an infected subject. Studies suggest that salivary viral load is correlated with disease severity and probability of transmission. Cetylpyridinium chloride mouthwash has been found to be effective in reducing salivary viral load. The aim of this systematic review of randomized controlled trials is to evaluate the efficacy of the mouthwash ingredient cetylpyridinium chloride on salivary viral load in SARS-CoV-2 infection.

Methods: Randomized controlled trials comparing cetylpyridinium chloride mouthwash with placebo and other mouthwash ingredients in SARS-CoV-2 positive individuals were identified and evaluated.

Results: Six studies with a total of 301 patients that met the inclusion criteria were included. The studies reported the efficacy of cetylpyridinium chloride mouthwashes in reduction on SARS-CoV-2 salivary viral load compared to placebo and other mouthwash ingredients.

Conclusion: Mouthwashes containing cetylpyridinium chloride are effective against salivary viral load of SARS-CoV-2 in vivo. There is also the possibility that the use of mouthwash containing cetylpyridinium chloride in SARS-CoV-2 positive subjects could reduce transmissibility and severity of COVID-19.

The onset and development of periodontitis centers around microbiota dysbiosis and disrupted host responses. Dynamic metabolic activities of the subgingival microbiota modify the polymicrobial community, shape the microenvironment, and modulate the host response. A complicated metabolic network exists in interspecies interactions between periodontal pathobionts and commensals, which can lead to the development of dysbiotic plaque. Dysbiotic subgingival microbiota undergo metabolic interactions with the host and disrupt host-microbe equilibrium. In this review, we discuss the metabolic profiles of the subgingival microbiota, the metabolic crosstalk in polymicrobial communities, including pathobionts and commensals, and the metabolic interactions between microbes and the host.

Background: Dental calculus is the result of dental plaque mineralization, originating from the tooth-associated bacterial biofilm. Recent evidence revealed that the dental calculus microbiome has a more complex composition than previously considered, including an unstructured mix of both aerobes and anaerobes bacteria. Actually, we lack information about the influence of host lifestyle factors, such as diet and health on this highly biodiverse ecosystem. Here, we provide a pilot study investigating dental calculus microbial biodiversity and its relation with the host diet.

Methods: We collected 40 dental calculus samples during routine dental inspection; deoxyribonucleic acid was extracted and analyzed through 16S amplicon sequencing, while dietary information was retrieved through a questionnaire. Associations between diet and oral bacteria taxonomy and functional pathways were statistically tested.

Results: Overall, microbiome composition was dominated by 10 phyla and 39 bacterial genera, which were differently distributed among samples. Cluster analysis revealed four main groups based on the taxonomic profile and two groups based on functional pathways. Each taxonomic cluster was dominated by different microbial biomarkers: Streptococcus, Rothia, Tannerella, Lautropia, and Fusobacterium. Bacteria genera and pathways were also associated with specific dietary elements, especially vegetable and fruit intake suggesting an overall effect of diet on dental calculus microbiome.

Conclusions: The present study demonstrates that there exists an inter-variability in the microbial composition of dental calculus among individuals of a rather homogeneous population. Furthermore, the observed biodiversity and microbial functions can find an association with specific dietary habits, such as a high-fiber diet or a protein-rich diet.

The Msp protein complex and the serine protease dentilisin are the best-characterized virulence factors in Treponema denticola, the major etiological agent of chronic periodontitis. In addition to these outer sheath factors, the cysteine protease dentipain contributes to pathogenicity, but its secretion, processing, cellular localization, and role in T. denticola virulence are not fully understood. In this study, we found that full-sized dentipain (74-kDa) and the 52-kDa truncated form of the enzyme are located, respectively, in the outer sheath derived from T. denticola dentilisin- and the Msp-deficient mutants. Furthermore, dentipain was barely detected in the wild-type strain. These results suggest that dentilisin and Msp, the major outer sheath proteins, are involved in the secretion and maturation of dentipain. Inactivation of the dentipain gene slowed the growth of T. denticola, and the effect was more profound in serum-free medium than in serum-containing medium. Several genes, including those encoding transporters and methyl-accepting chemotaxis proteins, were differentially expressed in the dentipain-deficient mutant. Furthermore, the mutant strain was more hydrophobic than the wild-type strain. Finally, the mutant showed less autoaggregation activity and adhesion to IgG in a serum-free medium than the wild-type strain. These findings suggest that dentipain contributes to the virulence of T. denticola by facilitating adhesion and acquisition of nutrients essential for colonization and proliferation in the gingival crevice under serum-rich conditions.

Most living organisms require zinc for survival; however, excessive amounts of this trace element can be toxic. Therefore, the frequent fluctuations of salivary zinc, caused by the low physiological level and the frequent introduction of exogenous zinc ions, present a serious challenge for bacteria colonizing the oral cavity. Streptococcus mutans is considered one of the main bacterial pathobiont in dental caries. Here, we verified the role of a P-type ATPase ZccE as the main zinc-exporting transporter in S. mutans and delineated the effects of zinc toxification caused by zccE deletion in the physiology of this bacterium. The deletion of the gene zccE severely impaired the ability of S. mutans to grow under high zinc stress conditions. Intracellular metal quantification using inductively coupled plasma optical emission spectrometer revealed that the zccE mutant exhibited approximately two times higher zinc accumulation than the wild type when grown in the presence of a subinhibitory zinc concentration. Biofilm formation analysis revealed less single-strain biofilm formation and competitive weakness in the dual-species biofilm formed with Streptococcus sanguinis for zccE mutant under high zinc stress. The quantitive reverse transcription polymerase chain reaction test revealed decreased expressions of gtfB, gtfC, and nlmC in the mutant strain under excessive zinc treatment. Collectively, these findings suggest that ZccE plays an important role in the zinc detoxification of S. mutans and that zinc is a growth-limiting factor for S. mutans within the dental biofilm.

Objectives: The objective of this study was to explore the effect of periodontitis on Th-cell subsets in local and systemic environments.

Methods: A total of 32 male Sprague-Dawley rats were randomly divided into periodontitis and control groups. Silk ligatures were applied to the mandibular first (M1) molars in the periodontitis group. Inflammation and alveolar bone loss around the M1 molars were analyzed by histological staining and microcomputed tomography. The mRNA expression of interferon-γ (IFN-γ), interleukin 4 (IL-4), IL-17, and IL-10 in the gingiva was measured by qRT-PCR. The proportions of Th1, Th2, Th17, and Treg cells in the submandibular lymph nodes, peripheral blood, and jaw bone marrow were tested using flow cytometry.

Results: More inflammatory cells and alveolar bone resorption were found in the periodontitis group, with upregulated mRNA expression of IFN-γ, IL-17, and IL-10. The proportion of Th1 and Th17 cells was significantly elevated in submandibular lymph nodes, and the proportion of Th1, Th2, and Th17 cells was significantly elevated in peripheral blood, while the proportion of Th1, Th17, and Treg cells was significantly elevated in jaw bone marrow in the periodontitis group.

Conclusion: This study suggests that periodontitis affects the differentiation of Th-cell subsets in both local and systemic environments, resulting in an increased proportion of proinflammatory cells.

Aim: The aim of this study was to evaluate the effects of Bdellovibrio bacteriovorus HD100 on experimental periodontitis (EP) in rats.

Methods: Thirty-two rats were divided into four groups: control, C-HD100 (B. bacteriovorus), EP, and EP-HD100. On day 0, EP was induced by the placement of cotton ligatures around the mandibular first molars (MFMs) in the EP and EP-HD100 groups. In the C-HD100 and EP-HD100 groups, suspensions containing 1 × 10⁹  PUF/ml of B. bacteriovorus HD100 were topically administered to the subgingival region of MFMs on days 0, 3, and 7. Animals were euthanized on day 14. Morphometrics analyses were performed in hemimandibles. The levels of tumor necrosis factor alpha (TNF-α), interleukin (IL)-6, monocyte chemoattractant protein (MCP)-1, IL-10, IL-1β, transforming growth factor beta (TGF-β), macrophage colony-stimulating factor (M-CSF) and regulated on activation and normal T cell expressed and secreted (RANTES) were determined by enzymatic immunoassays in gingival tissues. Beta defensin (BD)-1, BD-2, and BD-3, Toll-like receptors (TLR)-2 and TLR-4, and a cluster of differentiation (CD)-4, CD-8 and CD-57 were analyzed by immunohistochemistry in hemimandibles. Data were statistically analyzed.

Results: The EP group showed greater alveolar bone loss than EP-HD100 (p < .05). The EP-HD100 group showed higher levels of MCP-1, RANTES, IL-10, and TGF-β, lower levels of TNF-α than the EP group (p < .05). No differences were observed in IL-1β, IL-6, and M-CSF levels between EP and EP-HD100 groups. The C-HD100 group had higher IL-6, TNF-α, RANTES, and MCP-1 levels than the control group (p < .05). Regarding BD, the EP-HD100 group showed a larger immunolabeling pattern for BD-1, BD-2, and BD-3 than the EP group (p < .05). No significant differences in the immunolabeling pattern were observed for TLR-2, TLR-4, CD-4, CD-8, and CD-57 between EP and EP-HD100 groups.

Conclusion: The topical use of B. bacteriovorus HD100 reduces alveolar bone loss, increases expression of BD, and modulates the cytokines levels on periodontal tissues in rats with EP.

Rhesus monkeys (n = 36) exhibiting a healthy periodontium at baseline were used to induce progressing periodontitis through ligature placement around premolar/molar teeth. Bacterial samples were collected at baseline, 0.5, 1, and 3 months of disease and at 5 months for disease resolution. The animals were distributed into two groups (18/group): 3-7 years (young) and 12-23 years (adult) and stratified based upon matriline susceptibility to periodontitis (PDS, susceptible; PDR, resistant). A total of 444 operational taxonomic units (OTUs) with 100 microbes representing a core microbiome present in ≥75% of the samples were identified. Only 48% of the major phylotypes overlapped in the PDS and PDR samples. Different OTU abundance patterns were seen in young animals from the PDS and PDR matrilines, with qualitative similarities during disease and the relative abundance of phylotypes becoming less diverse. In adults, 23 OTUs were increased during disease in PDS samples and 24 in PDR samples; however, only five were common between these groups. Greater diversity of OTU relative abundance at baseline was observed with adult compared to young oral samples from both the PDS and PDR groups. With disease initiation (2 weeks), less diversity of relative abundance and some distinctive increases in specific OTUs were noted. By 1 month, there was considerable qualitative homogeneity in the major OTUs in both groups; however, by 3 months, there was an exacerbation of both qualitative and quantitative differences in the dominant OTUs between the PDS and PDR samples. These results support that some differences in disease expression related to matriline (familial) periodontitis risk may be explained by microbiome features.

The recently identified bacterium Tannerella serpentiformis is the closest phylogenetic relative of Tannerella forsythia, whose presence in oral biofilms is associated with periodontitis. Conversely, T. serpentiformis is considered health-associated. This discrepancy was investigated in a comparative study of the two Tannerella species. The biofilm behavior was analyzed upon their addition and of Porphyromonas gingivalis-each bacterium separately or in combinations-to an in vitro five-species oral model biofilm. Biofilm composition and architecture was analyzed quantitatively using real-time PCR and qualitatively by fluorescence in situ hybridization/confocal laser scanning microscopy, and by scanning electron microscopy. The presence of T. serpentiformis led to a decrease of the total cell number of biofilm bacteria, while P. gingivalis was growth-promoting. This effect was mitigated by T. serpentiformis when added to the biofilm together with P. gingivalis. Notably, T. serpentiformis outcompeted T. forsythia numbers when the two species were simultaneously added to the biofilm compared to biofilms containing T. forsythia alone. Tannerella serpentiformis appeared evenly distributed throughout the multispecies biofilm, while T. forsythia was surface-located. Adhesion and invasion assays revealed that T. serpentiformis was significantly less effective in invading human gingival epithelial cells than T. forsythia. Furthermore, compared to T. forsythia, a higher immunostimulatory potential of human gingival fibroblasts and macrophages was revealed for T. serpentiformis, based on mRNA expression levels of the inflammatory mediators interleukin 6 (IL-6), IL-8, monocyte chemoattractant protein-1 and tumor necrosis factor α, and production of the corresponding proteins. Collectively, these data support the potential of T. serpentiformis to interfere with biological processes relevant to the establishment of periodontitis.

Lactic acid bacteria have been widely used as probiotics for improving gut health. However, studies on oral probiotics were very limited. In this study, 67 lactic acid bacteria (LAB) were isolated from fermented food and screened for antagonistic activity against Streptococcus mutans, the causative pathogen of dental caries. Leuconostoc mesenteroides MJM60376 showed the highest antagonistic activity against S. mutans KCTC3065. L. mesenteroides MJM60376 also showed oral probiotic characteristics including weak acid production, lysozyme tolerance, adhesion to oral epithelial cell (YD-38), antibiotic susceptibility, and good coaggregation ability with S. mutans. Furthermore, the biofilm formation of S. mutans was significantly reduced when cocultured with L. mesenteroides. Scanning electron microscopy analysis showed that amounts of attached bacteria of S. mutans and network-like structures were significantly reduced by L. mesenteroides MJM60376. Cell-free supernatant (CFS) of L. mesenteroides MJM60376 also greatly inhibited biofilm formation of S. mutans from the adherent stage, the activity remained even after it was treated with catalase, trypsin, or pH neutralized. Expression levels of biofilm formation-related genes were significantly reduced in S. mutans when it was treated with the CFS of L. mesenteroides MJM60376. Therefore, L. mesenteroides MJM60376 has great potential to be used as a multifunctional ingredient.