[Materials for Selective Inhibition of Streptococcus mutans and Progress in Relevant Research]

Dental caries is a disease in which chronic progressive destruction of the hard dental tissues occurs under the influence of multiple factors, among which, bacterial infection being the most important one. Dental plaque biofilm is a key factor in the pathogenesis of dental caries. Under normal circumstances, microorganisms within the biofilm maintain a dynamic balance through coordination, competition, and antagonism. However, when the environment changes, the balance in the biofilm will be disrupted, and the number of cariogenic bacteria, especially Streptococcus mutans ( S. mutans), will increase significantly, thereby causing the production of large amounts of organic acids on the tooth surface, tooth demineralization, and the formation of dental caries. Therefore, finding ways to restore the dynamic balance of oral microorganisms through selective inhibition of S. mutans is key to the prevention and treatment of dental caries. Herein, we reviewed the research progress of recent years in the development of materials with selective antibacterial effect, intending to provide references for the further development of drugs for the prevention and treatment of dental caries. Future studies should focus on the following aspects, mechanism, clinical efficacy, chemical modification, and safety, to supplement and make improvements on the existing relevant research, and to promote progress in research and development of drugs for the prevention and treatment of dental caries.

[Regulatory Effect of All-Trans Retinoic Acid on the Expression of IL-1β in Macrophages and the Mechanisms Involved]

Objective

To investigate the regulatory effect of all-trans retinoic acid (ATRA) on the expression interleukin-1β (IL-1β) in macrophages and the mechanisms involved.

Methods

Macrophages were treated with 1 μmol/L ATRA for 24 h before RNA-Sequence. Differentially expressed genes (DEGs) were screened out and analyzed by Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, gene ontology (GO) functional analysis, and protein-protein interaction networks (PPI) analysis. After treatment with different doses of ATRA for 24 h, the expression of IL-1β was examined with qRT-PCR and Western blot. The activation of NF-κB signaling and caspase-1 was observed by Western blot and immunofluorescence staining.

Results

Compared with the blank control group, a total of 71 DEGs of macrophages were upregulated in the ATRA treatment group. KEGG analysis showed that the up-regulated DEGs were involved in IL-17 signaling pathway, tumor necrosis factor (TNF) signaling pathway, etc. GO analysis indicated that the up-regulated DEGs were involved in the biological processes of the production of IL-1β, response to lipopolysaccharide, etc. PPI analysis revealed that inflammatory cytokines, adhesion molecules, and chemokines were the key genes that ATRA acted on. In vitro experiments showed that ATRA promoted IL-1β expression in macrophages in a concentration-dependent manner. The expression of p-NF-κB, NF-κB, and caspase-1 were significantly increased by ATRA compared with those of the control group ( P<0.05), and p-NF-κB translocated to the cell nucleus in the ATRA group.

Conclusion

ATRA may promote the expression of IL-1β by activating NF-κB signaling and caspase-1 in macrophages, this study may provide evidence for the immune regulatory function of ATRA on macrophages.

[Microbial Diversity and Community Analysis of Dental Plaques in Orthodontic Patients Wearing Invisible Appliances and Fixed Appliances]

Objective

To explore the microbial diversity and community structure of dental plaques in orthodontic patients with invisible appliances and fixed appliances and to study the differences.

Methods

Ten orthodontic patients wearing invisible appliances (I) and ten wearing fixed appliances (F) were recruited. Dental plaques were collected from both buccal (B) and lingual (L) sides. Based on 16S rDNA, 40 dental plaque samples were analyzed after Illumina sequencing.

Results

The microbial diversity, abundance and evenness of the FB group were significantly higher than those of the IB and IL groups (P<0.05), while the FL group showed substantial individual differences. The community structures were generally similar among the four groups, but significant differences in the relative abundance of some bacteria were found. The IB group showed higher abundances of Actinomycetes and Rosella (P<0.05), which were considered to be involved in dental caries and periodontal diseases. Some key communities showing significant differences were significantly enriched in the FB group, including Coprobacillus, Bifidobacterium, Enterobacterium, Lactobacillus, etc..

Conclusion

Dental plaques in patients wearing invisible appliances and fixed appliances showed significantly different microbial abundance, diversity and composition, which may be involved in orthodontic complications such as dental caries and periodontal diseases. Orthodontic patients need strengthened measures for oral hygiene maintenance, no matter what kind of appliances they wear.

[Application Progress of Dual RNA Sequencing in Microbial Research]

The human body is colonized by densely-populated and structurally complex communities of microorganisms. The microbiota interact not only with their host cells, but also with other microbiota. Dual RNA sequencing (Dual RNA-seq) can be used to conduct simultaneous analysis of the dynamic changes of gene expression of two (or more) interactive species, and to obtain thus, through the interaction model diagram, the inter-species regulatory relationship of genes of different species, and hence the interaction mechanism between species. We herein reviewed the application status and development prospects of Dual RNA-seq in the research of intestinal, respiratory, skin and oral microbes. Since the concept of Dual RNA-seq was first introduced, the technology has been applied to a range of infection models. Direct investigation into the dynamic interactions between species at the molecular level will contribute to the better understanding of the physiological changes of pathogens and hosts during the course of infection, and thus help reveal potential new targets or biomarkers. However, the Dual RNA-seq technology is still in its early stage of development, and there are some limitations in the experimental technology. For example, due to the dynamic nature of the interaction between species, there are urgent problems awaiting solutions, such as the optimal experimental conditions, the selection of sampling sites and how to achieve real-time observation. In addition, due to the large amount of bioinformatics data of Dual RNA-seq, further research is needed to explore for ways to process the interaction information quickly and flexibly.