Mechanistic Effects of E-Liquids on Biofilm Formation and Growth of Oral Commensal Streptococcal Communities: Effect of Flavoring Agents

Tobacco-enhanced biofilm formation by Porphyromonas gingivalis and other oral microbes

Microbial biofilms promote pathogenesis by disguising antigens, facilitating immune evasion, providing protection against antibiotics and other antimicrobials and, generally, fostering survival and persistence. Environmental fluxes are known to influence biofilm formation and composition, with recent data suggesting that tobacco and tobacco-derived stimuli are particularly important mediators of biofilm initiation and development in vitro and determinants of polymicrobial communities in vivo. The evidence for tobacco-augmented biofilm formation by oral bacteria, tobacco-induced oral dysbiosis, tobacco-resistance strategies, and bacterial physiology is summarized herein. A general overview is provided alongside specific insights gained through studies of the model and archetypal, anaerobic, Gram-negative oral pathobiont, Porphyromonas gingivalis.

Effects of E-Liquids and Their Aerosols on Biofilm Formation and Growth of Oral Commensal Streptococcal Communities: Effect of Cinnamon and Menthol Flavors

(1) Background: The rise in electronic cigarette (E-cigarette) popularity, especially among adolescents, has prompted research to investigate potential effects on health. Although much research has been carried out on the effect on lung health, the first site exposed to vaping-the oral cavity-has received relatively little attention. The aims of this study were twofold: to examine the effects of E-liquids on the viability and hydrophobicity of oral commensal streptococci, and the effects of E-cigarette-generated aerosols on the biomass and viability of oral commensal streptococci. (2) Methods: Quantitative and confocal biofilm analysis, live-dead staining, and hydrophobicity assays were used to determine the effect on oral commensal streptococci after exposure to E-liquids and/or E-cigarette-generated aerosols. (3) Results: E-liquids and flavors have a bactericidal effect on multispecies oral commensal biofilms and increase the hydrophobicity of oral commensal streptococci. Flavorless and some flavored E-liquid aerosols have a bactericidal effect on oral commensal biofilms while having no effect on overall biomass. (4) Conclusions: These results indicate that E-liquids/E-cigarette-generated aerosols alter the chemical interactions and viability of oral commensal streptococci. Consequently, the use of E-cigarettes has the potential to alter the status of disease and health in the oral cavity and, by extension, affect systemic health.

The transcriptomic response to cannabidiol of Treponema denticola, a phytocannabinoid-resistant periodontal pathogen

AIM

The use of cannabis, which contains multiple antimicrobials, may be a risk factor for periodontitis. We hypothesized that multiple oral spirochetes would be phytocannabinoid-resistant and that cannabidiol (CBD) would act as an environmental stressor to which Treponema denticola would respond transcriptionally, thereby providing first insights into spirochetal survival strategies.

MATERIALS AND METHODS

Oral spirochete growth was monitored spectrophotometrically in the presence and absence of physiologically relevant phytocannabinoid doses, the transcriptional response to phytocannabinoid exposure determined by RNAseq, specific gene activity fluxes verified using qRT-PCR and orthologues among fully sequenced oral spirochetes identified.

RESULTS

Multiple strains of oral treponemes were resistant to CBD (0.1-10 μg/mL), while T. denticola ATCC 35405 was resistant to all phytocannabinoids tested (CBD, cannabinol [CBN], tetrahydrocannabinol [THC]). A total of 392 T. denticola ATCC 35405 genes were found to be CBD-responsive by RNAseq. A selected subset of these genes was independently verified by qRT-PCR. Genes found to be differentially activated by both methods included several involved in transcriptional regulation and toxin control. Suppressed genes included several involved in chemotaxis and proteolysis.

CONCLUSIONS

Oral spirochetes, unlike some other periodontal bacteria, are resistant to physiological doses of phytocannabinoids. Investigation of CBD-induced transcriptomic changes provided insight into the resistance mechanisms of this important periodontal pathogen. These findings should be considered in the context of the reported enhanced susceptibility to periodontitis in cannabis users.

The Role of Electronic Cigarettes in Dental Caries: A Scoping Review

Dental caries, a predominant childhood and adolescence affliction, has numerous factors implicated in its pathogenesis. Electronic cigarettes (ECs) have recently gained popularity among the younger population. Various factors, such as the EC liquid composition and aerosols, are associated with the development of dental caries. This review explains numerous EC-related factors which may lead to dental caries. An electronic search was conducted in Medline (Pubmed), Scopus, and Embase databases to evaluate the original research investigating the role of ECs in developing dental caries. About 12 included studies in the review indicated that factors such as the composition of e-liquids and aerosols are significant in the progression of dental caries. Specifically, cariogenic sugars such as sucrose, fructose, glucose, aldehydes, and flavors such as menthol, cinnamon, and strawberry in the e-liquids contribute to dental caries. They are toxic to oral commensals such as Streptococcus gordonii, Streptococcus mitis, Streptococcus intermedius, and Streptococcus oralis and promote the proliferation of cariogenic pathogens such as Streptococcus mutans (S. mutans) which causes dental caries. However, further validation of the effects of ECs on the development of dental caries is warranted through clinical trials.