Farnesol inhibits development of caries by augmenting oxygen sensitivity and suppressing virulence-associated gene expression inStreptococcus mutans

Inhibiting roles of farnesol and HOG in morphological switching of Candida albicans

Candida albicans is a major opportunistic fungal pathogen of humans, especially in the oral cavity it involves in precancerous lesions. Numerous transcriptional regulators and hypha-specific genes involved in the morphogenesis mechanisms have been identified. Its virulence is predominantly attributed to the potentiality of morphological switching from yeast and pseudohyphae to hyphal growth. Giving attention in farnesol for prevention or intervention of its virulence sense and possible etiologic role in some uncovered premalignant diseases, in addition, to be a quorum-sensing signal molecule and relationship with HOG pathway, although its morphological switching inhibiting function has attracted high attention and got great progress in being elucidated, their exact mode of action is not completely understood. This report provides a review of characteristic aspects of farnesol signaling and HOG pathway during hyphal development. It also includes other associated pathways, molecules, and novel drug development based on the latest researches over the last decade. Furthermore, farnesol as immunomodulatory to host is an important inferring.

Effects of Rhein-8-O-β-D-glucopyranoside on the Biofilm Formation of Streptococcus mutans

Dental caries is the most frequent biofilm-related human infectious disease in the oral cavity. Streptococcus mutans is one of the primary etiological agents of dental caries. The aim of our study was to investigate the effects of rhein-8-O-β-D-glucopyranoside (Rg) on the development of S. mutans biofilms. Growth curves were generated, and biofilm oxygen sensitivity was detected after Rg treatment. The expression levels of luxS, brpA, ffh, recA, nth, and smx were analyzed by real-time PCR. The trypan blue exclusion assay was used to measure the effect of Rg on monocyte viability. The results showed that Rg could significantly inhibit the growth of S. mutans and suppress the biofilm formation of S. mutans in a concentration-dependent manner. In Rg-treated biofilms, the expression levels of luxS, brpA, ffh, recA, nth, and smx were all decreased. Our results further showed that Rg was nontoxic, as Rg did not affect monocyte viability or lactate dehydrogenase activity in the exposed cells. These results suggested that Rg inhibited the biofilm formation of S. mutans, and the decrease in luxS, brpA, ffh, recA, nth, and smx expression might contribute to the antibacterial effects of Rg.

Probiotic Effects of Lactobacillus paracasei 28.4 to Inhibit Streptococcus mutans in a Gellan-Based Formulation

Streptococcus mutans is considered to be a major bacterium involved in dental caries, and the control of virulence mechanisms is fundamental to prevent disease. Probiotics present a promising preventive method; however, the use of probiotics requires its incorporation into delivery materials to facilitate oral colonization. Thus, we performed a comprehensive study examining preventive effects of Lactobacillus paracasei 28.4-enriched gellan hydrogel materials to inhibit S. mutans in planktonic and biofilm states, addressing its influence in the production of extracellular polysaccharides (EPS) and altered gene expression of several cariogenic virulence factors. L. paracasei 28.4, a strain isolated from the oral cavity of a caries-free individual, was incorporated in three gellan hydrogels (0.5%, 0.75%, and 1% w/v). The pretreatment with probiotic-gellan formulations provided a release of L. paracasei cells over 24 h that was sufficient to inhibit the planktonic growth of S. mutans, independent of the gellan concentrations and pH variations. This pretreatment also had inhibitory activity against S. mutans biofilms, exhibiting a reduction of 0.57 to 1.54 log₁₀ in CFU/mL (p < 0.0001) and a decrease of 68.8 to 71.3% in total biomass (p < 0.0001) compared with the control group. These inhibitory effects were associated with the decreased production of EPS by 80% (p < 0.0001) and the downregulation of luxS, brpA, gbpB, and gtfB genes. The gellan formulation containing L. paracasei 28.4 exhibited probiotic effects for preventing S. mutans growth, biofilm formation, and production of cariogenic factors to suggest possible use in tooth decay prevention.

A universal adhesive incorporating antimicrobial peptide nisin: effects on Streptococcus mutans and saliva-derived multispecies biofilms

For purpose of enhancing the antibacterial activity of a universal adhesive, the antimicrobial peptide nisin was incorporated into Single Bond Universal and its antibacterial effect on Streptococcus mutans monospecific biofilms and saliva-derived multispecies biofilms was studied. Nisin was incorporated into Single Bond Universal and the antibacterial activity was examined by confocal laser scanning microscopy (CLSM), reverse transcription-quantitative polymerase chain reaction (qRT-PCR), phenol-sulfuric acid method and lactate dehydrogenase enzymatic method. The bonding properties were tested by microtensile bond strength (μTBS) and degree of conversion (DC). Data were analyzed by one-way analysis of variance (ANOVA) and least significant difference multiple comparison tests (P < 0.05). The Single Bond Universal incorporated with 3% (w/v) nisin could significantly inhibit the growth of the S. mutans monospecific biofilms (P< 0.01) and decrease the expression of genes related to extracellular polysaccharide (EPS) synthesis (gtfB, gtfC, gtfD and spaP) and acidogenicity (ldh) (P < 0.05). 3% (w/v) nisin-incorporated Single Bond Universal could also inhibit the growth of saliva-derived multispecies biofilms and decrease the excretion of EPS and lactic acid ( P< 0.05). μTBS and DC of 3% (w/v) nisin-incorporated Single Bond Universal did not deteriorate obviously (P > 0.05). In conclusion, 3% (w/v) nisin-incorporated Single Bond Universal substantially inhibited the growth of both S. mutans monospecific and saliva-derived multispecies biofilms without compromising the bonding properties.

Trans,trans-farnesol, an antimicrobial natural compound, improves glass ionomer cement properties

A series of experiments were conducted to characterize a novel restorative material. We explored the effect on biological, physical and chemical properties of glass ionomer cement (GIC) adding-the naturally occurring tt-farnesol (900 mM). Two groups were accomplished for all assays: GIC+tt-farnesol and GIC (control). Biological assays: 1) agar diffusion against some cariogenic bacteria; 2) S. mutans biofilm formation and confocal laser scanning microscopy-CLSM. 3) gtfB, gtfC, gtfD, gbpB, vicR, and covR expression; 4) MTT and microscopic morphology. Physical properties assays: 1) roughness; 2) hardness; 3) compressive strength and 4) diametral tensile strength. Chemical assay: Raman spectroscopy. The adding of tt-farnesol to GIC led to larger zones of inhibition (p<0.05), biofilms with a short-term reduction in bacterial viability but similar biomass (p>0.05). Polysaccharides levels increased over time, similarly over groups (p>0.05). Viable and non-viable S. mutans were seen on the specimens’ surface by CLSM but their virulence was not modulated by tt-farnesol. The tt-farnesol increased the HaCaT cell viability without impact on compressive and diametral tensile strength and roughness although the hardness was positively affected (p<0.05). Raman confirmed the presence of tt-farnesol. The incorporation of tt-farnesol into GIC inhibited the growth of cariogenic bacteria but had a little effect on the composition, structure and physiology of the biofilm matrices. Also, the tt-farnesol increased the hardness and the biocompatibility of the GIC, not influencing negatively other physical properties of the restorative material.