Polymicrobial interactions of Candida albicans and its role in oral carcinogenesis

The oral microbiome is composed of microorganisms residing in the oral cavity, which are critical components of health and disease. Disruption of the oral microbiome has been proven to influence the course of oral diseases, especially among immunocompromised patients. Oral microbiome is comprised of inter‐kingdom microorganisms, including yeasts such as Candida albicans, bacteria, archaea and viruses. These microorganisms can interact synergistically, mutualistically and antagonistically, wherein the sum of these interactions dictates the composition of the oral microbiome. For instance, polymicrobial interactions can improve the ability of C. albicans to form biofilm, which subsequently increases the colonisation of oral mucosa by the yeast. Polymicrobial interactions of C. albicans with other members of the oral microbiome have been reported to enhance the malignant phenotype of oral cancer cells, such as the attachment to extracellular matrix molecules (ECM) and epithelial mesenchymal transition (EMT). Polymicrobial interactions may also exacerbate an inflammatory response in oral epithelial cells, which may play a role in carcinogenesis. This review focuses on the role of polymicrobial interactions between C albicans and other oral microorganisms, including its role in promoting oral carcinogenesis

The effect of polymicrobial interaction on the adhesion of OKF6 and H357 cell lines

Introduction: Oral cancer is classified as the sixth most common cancer in the world. It has been suggested that polymicrobial infection may have a role in oral carcinogenesis. Objective: To determine the effect of mono-culture and polymicrobial biofilms effluent from C. albicans, Streptococcus mutans and Actinomyces naeslundii to the adhesion of normal and oral cancer cell lines on extra-cellular matrix (ECM) molecules coated surfaces. Methods: Initially, OKF6 cell line isolated from healthy oral cavity was incubated in serum free medium containing effluent from mono-culture or polymicrobial biofilms of C. albicans (ALC3), S. mutans (Ingbritt), A. naelundii (NCTC 10301) for 90 minutes. Following that, the suspension was added into CytoSelect 48-well Cell Adhesion Assay ECM Array kit to determine the adhesion of the cell to fibronectin, collagen I, collagen IV, laminin and fibrinogen. Fold change of adhesion of the cells incubated in biofilm effluent in comparison to that incubated in non-effluent (NE) was enumerated. Similar protocol was repeated with H357 cell line that was isolated from patient with oral squamous cell carcinoma (OSCC). Results: The majority of OKF6 cells incubated in biofilm effluent exhibited significantly decreased adhesion to ECM molecules compared to the cells incubated in NE (P<0.05). Only when incubated with S. mutans effluent, OKF6 cells exhibited significant increase in adhesion to fibronectin (P<0.05). The incubation of H357 with C. albicans effluent exhibited significant increase of adhesion to collagen IV and laminin I when compared to NE (P < 0.05). Furthermore, the adhesion of H357 cells to laminin I were also found to increase when incubated with C. albicans (15.07-fold), S. mutans (6.54-fold), A. naeslundii (1.31-fold) and polymicrobial biofilms (10.69-fold) effluents. Conclusions: The adhesion of OKF6 and H357 to ECM are biofilm effluent-dependent and that biofilm effluent enhance the malignant phenotype of H357 when grown in medium containing biofilms effluent

The effect of Candida albicans, Actinomyces naeslundii and Streptococcus mutans biofilm effluent on the expression of interleukin-6 and interleukin-8 from normal and oral cancer cell lines

Abstract: Oral cancer is the sixth most common cancer worldwide. It is suggested that polymicrobial infection may involve in oral carcinogenesis. This study aimed to determine the effect of mono-culture and polymicrobial biofilms effluent from C. albicans, Streptococcus mutans and Actinomyces naeslundii to the expression of Interleukin-6 (IL-6) and Interleukin-8 (IL-8) from normal and oral squamous cell carcinoma (OSCC) cell lines, with the hypothesis that biofilm effluent promote oral carcinogenesis. OKF6 cell line isolated from healthy oral cavity was grown to 80% confluent in 12-well plate and incubated with 80% (v/v) serum free medium (SFM) containing biofilm effluent from mono-culture of C. albicans (ALC3), S. mutans (SM), A. naelundii (AN) or polymicrobial (TRI) for 2 h and 24 h. Incubation of the cell line with 100% SFM (NE) was conducted to represent the negative control. To quantify the amount of IL-6 and IL-8 secreted by epithelial cells in response to biofilm effluent, the conditioned medium was collected and analysed using Bio-Plex protein array system and Bio-Rad cytokine multi-plex panel. Similar protocol was repeated with H357 cell line that was isolated from patient with OSCC. The results showed that OKF6 cell line that was incubated with ALC3 had significant decrease IL-8 expression while incubation with SM exhibited significantly increase IL-6 expression when compared to NE after 2 h incubation (P<0.05). In addition, significant increase of IL-6 and IL-8 expression were observed after 24 h incubation of OKF6 cell line with TRI effluent when compared to NE (P<0.05). The incubation of H357 with AN, SM and TRI effluent exhibited significant increase of IL-6 and IL-8 expression after 2 h incubation, whereas significant increase of the similar cytokines were observed when incubated with all effluent after 24 h in comparison to NE (P<0.05). In conclusion, biofilm effluent promotes malignant phenotype of OSCC cell line

Coaggregation of Candida albicans, Actinomyces naeslundii and Streptococcus mutans is Candida albicans strain dependent

Microbial interactions are necessarily associated with the development of polymicrobial oral bio lms. The objective of this study was to determine the coaggregation of eight strains of Candida albicans with Actinomyces naeslundii and Streptococcus mutans. In autoaggregation assays, C. albicans strains were grown in RPMI-1640 and arti cial saliva medium (ASM) whereas bacteria were grown in heart infusion broth. C. albicans, A. naeslundii and S. mutans were suspended to give 106, 107 and 108 cells mL−1 respectively, in coaggregation buffer followed by a 1 h incubation. The absorbance difference at 620 nm ( Abs) between 0 h and 1 h was recorded. To study coaggregation, the same protocol was used, except combinations of microorganisms were incubated together. The mean Abs% of autoaggregation of the majority of RPMI-1640-grown C. albicans was higher than in ASM grown. Coaggregation of C. albicans with A. naeslundii and/or S. mutans was variable among C. albicans strains. Scanning electron microscopy images showed that A. naeslundii and S. mutans coaggregated with C. albicans in dual- and triculture. In conclusion, the coaggregation of C. albicans, A. naeslundii and S. mutans is C. albicans strain dependent

Trends in social inequalities in early childhood caries using population-based clinical data

OBJECTIVE: To assess the longitudinal trends in social inequalities in early childhood caries (ECC) using collected population-based data. METHODS: Clinical data on children were routinely collected from 2008 to 2019 in Victoria, Australia. ECC prevalence and severity (dmft) were quantified according to Indigenous status, culturally and linguistically diverse (CALD) status, concession cardholder status, geographic remoteness and area deprivation. The inverse probability weighting was used to quantify social inequalities in ECC. The weighted prevalence differences, and the ratio between the weighted prevalence of ECC and mean dmft and their 95% confidence interval, were then plotted. RESULTS: Absolute inequalities in ECC prevalence increased for children by 7% for CALD status and cardholder status between 2008 and 2019. Likewise, absolute inequalities in ECC severity in this time period increased by 0.6 for CALD status and by 0.4 for cardholder status. Relative inequalities in ECC increased by CALD (ratio: 1.3 to 2.0), cardholder status (1.3 to 2.0) and area deprivation (1.1 to 1.3). Relative inequalities in severity increased by CALD (1.5 to 2.8), cardholder (1.4 to 2.5) or area deprivation (1.3 to 1.5). Although children with Indigenous status experienced inequalities in ECC prevalence and severity, these did not increase on the absolute (ECC: 0.1-0.1 Severity: 1.0-0.1) or relative scale (ECC ratio: 1.3-1.3 Severity ratio: 1.6-1.1). CONCLUSIONS: Trends in inequalities in ECC were different according to sociodemographic measures. Oral health policies and interventions must be evaluated on the basis of reducing the prevalence of oral diseases and oral health inequalities between population sub-groups

Incorporation of the microencapsulated antimicrobial agent phytoncide into denture base resin

Background This study aimed to fabricate a denture base resin (DBR) containing phytoncide microcapsules (PTMCs) and determine the mechanical properties of the resin and antifungal activity. Methods Fifty‐four heat cured rectangular DBR specimens (64 x 10 x 3.3 ± 0.2 mm) containing nine concentrations of PTMC between 0 ‐ 5% (wt/wt) were fabricated and subjected to a three‐point bending test. A phytoncide release bioassay was developed using DBR containing 0% and 2.5% PTMCs (wt/wt) in a 24 well‐plate assay with incubation of Porphyromonas gingivalis at 37°C for 74 h. The antifungal activity of PTMCs against Candida albicans, in a pH 5.5 acidic environment was determined in a plate assay. Results Flexural strength decreased with increasing PTMC concentration from 97.58 ± 4.79 MPa for the DBR alone to 53.66 ± 2.46 MPa for DBR containing 5.0% PTMC. No release of phytoncide from the PTMCs in the DBR was detected at pH 7.4. The PTMCs had a minimal inhibitory concentration of 2.6% (wt/vol) against C. albicans at pH 5.5. Conclusions PTMCs can be added to DBR 2.5% (wt/wt) without adversely affecting flexural strength. PTMCs released the antimicrobial agent at pH 5.5 at concentrations sufficient to inhibit the growth of the C. albicans

Monospecies and polymicrobial biofilms differentially regulate the phenotype of genotype-specific oral cancer cells

Microbial infection has been shown to involve in oral carcinogenesis; however, the underlying mechanisms remain poorly understood. The present study aimed to characterize the growth of oral microorganisms as both monospecies and polymicrobial biofilms and determine the effects of their products on oral keratinocytes. Candida albicans (ALC3), Actinomyces naeslundii (AN) and Streptococcus mutans (SM) biofilms or a combination of these (TRI) were grown in flow-cell system for 24 h. The biofilms were subjected to fluorescent in situ hybridization using species-specific probes and analysed using confocal laser scanning microscopy. The effluent derived from each biofilm was collected and incubated with malignant (H357) and normal (OKF6) oral keratinocytes to assess extracellular matrix adhesion, epithelial–mesenchymal transition (EMT) and cytokines expression. Incubation of OKF6 with ALC3 and TRI effluent significantly decreased adhesion of the oral keratinocyte to collagen I, whereas incubation of H357 with similar effluent increased adhesion of the oral keratinocyte to laminin I, significantly when compared with incubation with artificial saliva containing serum-free medium (NE; P < 0.05). In OKF6, changes in E-cadherin and vimentin expression were not consistent with EMT although there was evidence of a mesenchymal to epithelial transition in malignant oral keratinocytes incubated with AN and SM effluent. A significant increase of pro-inflammatory cytokines expression, particularly interleukin (IL)-6 and IL-8, was observed when H357 was incubated with all biofilm effluents after 2- and 24-h incubation when compared with NE (P < 0.05). In conclusion, C.albicans, A.naeslundii and S.mutans form polymicrobial biofilms which differentially modulate malignant phenotype of oral keratinocytes

Nutrition and oral health in early childhood: associations with formal and informal childcare

Objective: To examine associations between childcare type and nutrition and oral health indicators. Design: Cross-sectional data extracted from a longitudinal birth cohort. Parent-completed FFQ and questions regarding oral health and childcare use. The associations between childcare type, classified into four groups: parent care only (PCO), formal childcare only (FCO), informal childcare only (ICO) or combination of care (F&I), and nutrition and oral health indicators were examined. Setting: Home and childcare. Participants: Families with children aged 3 years (n 273) and 4 years (n 249) in Victoria, Australia. Results: No associations were observed between childcare type and core food/beverage consumption or oral health indicators. For discretionary beverages, compared with children receiving PCO at age 3 years, children in FCO or F&I were less likely to frequently consume fruit juice/drinks (FCO: adjusted OR (AOR) 0·41, 95 % CI 0·17, 0·96, P = 0·04; F&I: AOR 0·32, 95 % CI 0·14, 0·74, P = 0·008). At age 4 years, children receiving FCO or ICO were less likely to consume sweet beverages frequently compared with children receiving PCO: fruit juice/drink (ICO: AOR 0·42, 95 % CI 0·19, 0·94, P = 0·03; FCO: AOR 0·35, 95 % CI 0·14, 0·88, P = 0·03) and soft drink (ICO: AOR 0·23, 95 % CI 0·07, 0·74, P = 0·01; FCO: AOR 0·14, 95 % CI 0·03, 0·76, P = 0·02). Conclusions: Associations between childcare type and discretionary beverage intake were observed. Investigation into knowledge, attitudes and activities in formal and informal childcare settings is required to explore different health promotion practices that may influence nutrition and oral health

Comparative transcriptomic analysis of Porphyromonas gingivalis biofilm and planktonic cells

<p>Abstract</p> <p>Background</p> <p><it>Porphyromonas gingivalis </it>in subgingival dental plaque, as part of a mature biofilm, has been strongly implicated in the onset and progression of chronic periodontitis. In this study using DNA microarray we compared the global gene expression of a <it>P. gingivalis </it>biofilm with that of its planktonic counterpart grown in the same continuous culture.</p> <p>Results</p> <p>Approximately 18% (377 genes, at 1.5 fold or more, <it>P</it>-value < 0.01) of the <it>P. gingivalis </it>genome was differentially expressed when the bacterium was grown as a biofilm. Genes that were down-regulated in biofilm cells, relative to planktonic cells, included those involved in cell envelope biogenesis, DNA replication, energy production and biosynthesis of cofactors, prosthetic groups and carriers. A number of genes encoding transport and binding proteins were up-regulated in <it>P. gingivalis </it>biofilm cells. Several genes predicted to encode proteins involved in signal transduction and transcriptional regulation were differentially regulated and may be important in the regulation of biofilm growth.</p> <p>Conclusion</p> <p>This study analyzing global gene expression provides insight into the adaptive response of <it>P. gingivalis </it>to biofilm growth, in particular showing a down regulation of genes involved in growth and metabolic activity.</p

The role of Candida albicans candidalysin ECE1 gene in oral carcinogenesis

Oral squamous cell carcinoma is associated with many known risk factors including tobacco smoking, chronic alcoholism, poor oral hygiene, unhealthy dietary habits and microbial infection. Previous studies have highlighted Candida albicans host tissue infection as a risk factor in the initiation and progression of oral cancer. C. albicans invasion induces several cancerous hallmarks, such as activation of proto-oncogenes, induction of DNA damage and overexpression of inflammatory signalling pathways. However, the molecular mechanisms behind these responses remain unclear. A recently discovered fungal toxin peptide, candidalysin, has been reported as an essential molecule in epithelial damage and host recognition of C albicans infection. Candidalysin has a clear role in inflammasome activation and induction of cell damage. Several inflammatory molecules such as IL-6, IL-17, NLRP3 and GM-CSF have been linked to carcinogenesis. Candidalysin is encoded by the ECE1 gene, which has been linked to virulence factors of C albicans such as adhesion, biofilm formation and filamentation properties. This review discusses the recent epidemiological burden of oral cancer and highlights the significance of the ECE1 gene and the ECE1 protein breakdown product, candidalysin in oral malignancy. The immunological and molecular mechanisms behind oral malignancy induced by inflammation and the role of the toxic fungal peptide candidalysin in oral carcinogenesis are explored. With increasing evidence associating C albicans with oral carcinoma, identifying the possible fungal pathogenicity factors including the role of candidalysin can assist in efforts to understand the link between C albicans infection and carcinogenesis, and pave the way for research into therapeutic potentials