Interactions between host and oral commensal microorganisms are key events in health and disease status

Cytotoxic effects of different detergent containing children's toothpastes on human gingival epithelial cells

Background

This study aimed to evaluate possible cytotoxic effects to gingival epithelial cells exposed to children toothpastes containing different detergent.

Methods

Tissues required for the isolation of human gingival epithelial cells were obtained by biopsy during the extraction of the impacted third molar tooth. Toothpaste solutions of different concentrations were prepared from five different children’s toothpastes with different detergent contents. Isolated gingival epithelial cells were stimulated with experimental groups consisting of toothpaste solutions (Colgate, Sensodyne, Splat, Nenedent, Perlodent) at different concentrations and a control group consisting of complete Dulbecco’s modified eagle medium. After the experiments, cell viability was evaluated using flow cytometry. 2 Way ANOVA was used to see the interaction effect of the main effects of toothpaste solution and concentration factors. Pairwise comparisons were made by Tukey post hoc tests. In the study, the significance level was taken as 0.05.

Results

As a result of the analysis, it was seen that the toothpaste solution and concentration factors and the interactions of these 2 factors were effective on the viable, early apoptotic, late apoptotic and necrotic cell rates. The statistically highest live cell ratios were detected in Splat’s toothpaste solutions (90.14% at 0.4% concentration) after the control group (90.82%) and the group with the lowest viability values was determined in Colgate group (75.74% at 0.4% concentration) (p < 0.05).

Conclusions

According to the results of the study, it was observed that toothpastes containing SLS affected the viability of cells more negatively than toothpastes with other detergent contents.

Three-Dimensional In Vitro Oral Mucosa Models of Fungal and Bacterial Infections

Oral mucosa is the target tissue for many microorganisms involved in periodontitis and other infectious diseases affecting the oral cavity. Three-dimensional (3D) in vitro and ex vivo oral mucosa equivalents have been used for oral disease modeling and investigation of the mechanisms of oral bacterial and fungal infections. This review was conducted to analyze different studies using 3D oral mucosa models for the evaluation of the interactions of different microorganisms with oral mucosa. In this study, based on our inclusion criteria, 43 articles were selected and analyzed. Different types of 3D oral mucosa models of bacterial and fungal infections were discussed in terms of the biological system used, culture conditions, method of infection, and the biological endpoints assessed in each study. The critical analysis revealed some contradictory reports in this field of research in the literature. Challenges in recovering bacteria from oral mucosa models were further discussed, suggesting possible future directions in microbiomics, including the use of oral mucosa-on-a-chip. The potential use of these 3D tissue models for the evaluation of the effects of antiseptic agents on bacteria and oral mucosa was also addressed. This review concluded that there were many aspects that would require optimization and standardization with regard to using oral mucosal models for infection by microorganisms. Using new technologies-such as microfluidics and bioreactors-could help to reproduce some of the physiologically relevant conditions and further simulate the clinical situation. Impact statement Tissue-engineered or commercial models of the oral mucosa are very useful for the study of diseases that involve the interaction of microorganisms and oral epithelium. In this review, challenges in recovering bacteria from oral mucosa models, the potential use of these three-dimensional tissue models for the evaluation of the effects of antiseptic agents, and future directions in microbiomics are discussed.

A narrative review of the effects of sugar-sweetened beverages on human health: A key global health issue

The provision of healthy and safe food is vital for human health, and the addition of unnecessary sugars in foodstuffs is an important global issue, leading to multiple long- and short-term health issues and spiraling costs for individuals and governments alike. The negative effect of excess sugar consumption contributes to adverse health conditions, including obesity, type 2 diabetes, and poor oral health in both high and low resource settings. A key plank of governmental and health promotion bodies' nutritional guidance is to raise public awareness of "hidden" sugars, salt, and fats, such as found in processed foods and sugar-sweetened beverages (SSBs), and guide individuals to reduce their consumption. This rapid narrative review brings together some of the key issues identified in the literature around the consumption of SSBs, including patterns of consumption, the general impact on human health and nutrition, specific effects on oral health and the oral microbiome, and strategies to address over-consumption. The range of long-term adverse effects on health is often misunderstood or unknown by the public. However, some strategies have succeeded in reducing the consumption of SSBs, including public health strategies and interventions and the imposition of taxes or levies, and this article makes recommendations for action.

Commensal and pathogenic biofilms differently modulate peri-implant oral mucosa in an organotypic model

The impact of oral commensal and pathogenic bacteria on peri-implant mucosa is not well understood, despite the high prevalence of peri-implant infections. Hence, we investigated responses of the peri-implant mucosa to Streptococcus oralis or Aggregatibacter actinomycetemcomitans biofilms using a novel in vitro peri-implant mucosa-biofilm model. Our 3D model combined three components, organotypic oral mucosa, implant material, and oral biofilm, with structural assembly close to native situation. S. oralis induced a protective stress response in the peri-implant mucosa through upregulation of heat shock protein (HSP70) genes. Attenuated inflammatory response was indicated by reduced cytokine levels of interleukin-6 (IL-6), interleukin-8 (CXCL8), and monocyte chemoattractant protein-1 (CCL2). The inflammatory balance was preserved through increased levels of tumor necrosis factor-alpha (TNF-α). A. actinomycetemcomitans induced downregulation of genes important for cell survival and host inflammatory response. The reduced cytokine levels of chemokine ligand 1 (CXCL1), CXCL8, and CCL2 also indicated a diminished inflammatory response. The induced immune balance by S. oralis may support oral health, whereas the reduced inflammatory response to A. actinomycetemcomitans may provide colonisation advantage and facilitate later tissue invasion. The comprehensive characterisation of peri-implant mucosa-biofilm interactions using our 3D model can provide new knowledge to improve strategies for prevention and therapy of peri-implant disease.

Restoring balance: biofilms and wound dressings

Biofilms are responsible for stimulating and maintaining wound inflammation, increasing infection risk and delaying wound closure. Appropriate biofilm management is required to fight against local and systemic infection and to restore balance to the wound environment. The most effective way to remove biofilms involves the use of mechanical techniques, with the wound dressing representing an important component of this strategy. Wound dressing fibres, such as polyacrylate fibres, have been shown to be effective in affecting biofilm architecture by disrupting the biofilm matrix. This helps enhance the efficacy of antimicrobials, such as silver. Focusing an antibiofilm strategy on active agents alone does not constitute a sustainable approach to biofilm management. Furthermore, adding too many active chemicals into a wound can be highly detrimental to the wound bed, and potentially may have both short- and long-term biological concerns. Particular attention on the characteristics and key features of wound dressings is discussed in this paper. The aim of the paper is to review the ideal characteristics of wound dressings, in conjunction with antimicrobials, that are considered a fundamental part of an antibiofilm strategy and growing requirement for enhanced wound healing.

Diversity and functional analysis of salivary microflora of Indian Antarctic expeditionaries

Introduction: The human oral microbiota continues to change phenotype by many factors (environment, diet, genetics, stress, etc.), throughout life with a major impact on human physiology, psychology, metabolism and immune system. Amongst one such factor with unique and extreme environmental conditions is Antarctica. The sea voyage to Antarctica has many risks than at station for expedition members. In this study, we investigated the influence of Antarctic sea voyage and stay at the Indian Antarctic station Maitri, on the health of Indian expedition members by using a metagenomic approach to explore oral biodiversity. Methods: Saliva samples were collected from 12 expedition members, at 3 different time points viz. before the start of the ship voyage, after the completion of the voyage and at the end of the stay at Antarctica. Samples were analyzed for whole genome and 16S rRNA sequencing. Result: The oral microbial diversity of the expedition members was significantly changed, during the days of sailing and after the stay at Antarctica. The oral microbiota comprised mainly of the phyla Firmicutes (46%, 29% & 36%); Proteobacteria (40%, 48%, & 44%), Bacteroidetes (10%, 22%, &14%), Fusobacterium and Actinobacteria (5%-1%) and Unclassified (17%, 25% & 23%), at three time points, respectively. Further, the differential analysis of microbes across all the phyla revealed 89, 157 and 157 OTUs genera. The altered microbiota indicated changes in amino acid, lipid and carbohydrate metabolism. Conclusion: Study suggests that understanding the compositional and functional differences in the oral microbiota of Antarctic expedition members, can lay the foundation to relate these differences to their health status. It will further demonstrate the need for providing improved management during ship voyage and stay in Antarctica.

The evaluation of the transport medium for extracted premolars prior to cryopreservation: an in vitro study

Autotransplantation is a versatile technique for the replacement of a missing tooth and cryopreservation can expand its scope. The aim of this in vitro study is to compare the antimicrobial effect of different transport protocols on procured teeth prior to cryopreservation. Streptococcus oralis biofilms were grown on ten sterile premolars, incubated for 48 h and subjected to the following transport procedures: an untreated (contaminated) control group, a group rinsed with phosphate buffered saline (PBS), a group transported in PBS, a group transported in Dulbecco's Modified Eagle's medium (DMEM) supplemented with fetal calf serum (FCS), and a group transported in DMEM supplemented with FCS and antibiotics (AB). The effect of cryopreservation as such, as well as the combination with a transport medium (DMEM + FCS + AB) on the contamination was also tested. The surviving bacteria were harvested, and determined by plate counting. There was no significant reduction in contamination after rinsing the tooth, after transport in PBS or after transport in DMEM with FCS. Significant reductions were observed for transport in DMEM with AB when compared to the control group (p = 0.003). Cryopreservation as such reduced the biofilm significantly (p < 0.001). No cumulative effect could be found when transport in DMEM + FCS + AB was followed by cryopreservation. Within the limitations of this laboratory set-up, DMEM + FCS + AB was the most effective transport medium in S. oralis biofilm elimination. It could not be concluded that rinsing of the tooth gives an additional reduction. Cryopreservation as such decontaminated the teeth more effectively than any tested transport procedure.

The evaluation of the transport medium for extracted premolars prior to cryopreservation: a systematic literature review

Prior to cryopreservation, a tooth is transported from a contaminated oral environment to the tooth bank. Our objective was to identify all studies reporting or investigating a transport protocol prior to the cryopreservation of teeth, in terms of decontamination of the subjects. The systematic literature search (1970-2017) was based on MEDLINE via PubMed, Web of Science and the Cochrane Library. The reference lists of the included studies and the Science Citation Index were used for hand searching (snowballing). Only studies reporting the transport conditions of the transplant were included. Language restrictions for English, Dutch or French were applied. The search led to 14 eligible studies. Almost all studies were laboratory studies, so the methodological quality of evidence was low. The majority of the included studies was performed by only five different research groups and the number of subjects varied between 1 and 120 teeth. In general, the teeth were stored in a tissue culture medium supplemented with fetal calf serum and/or different combinations of antibiotics and/or antimycotics. The teeth were transported cooled (4 °C) or at room temperature, for a period of time not exceeding 24 h. Only three studies reported the irrigation of the teeth with phosphate buffered saline prior to the transport. The optimisation of the decontamination during transport was investigated in three studies (from 1971, 1980 and 1982). It was concluded that the literature on this topic is scarce, and the decontamination protocol for teeth, prior to cryopreservation has not been validated recently.

Metagenomic sequencing reveals altered metabolic pathways in the oral microbiota of sailors during a long sea voyage

Seafaring is a difficult occupation, and sailors face higher health risks than individuals on land. Commensal microbiota participates in the host immune system and metabolism, reflecting the host's health condition. However, the interaction mechanisms between the microbiota and the host's health condition remain unclear. This study reports the influence of long sea voyages on human health by utilising a metagenomic analysis of variation in the microbiota of the buccal mucosa. Paired samples collected before and after a sea-voyage were analysed. After more than 120 days of ocean sailing, the oral microbial diversity of sailors was reduced by approximately 5 fold, and the levels of several pathogens (e.g., Streptococcus pneumonia) increased. Moreover, 69.46% of the identified microbial sequences were unclassified microbiota. Notably, several metabolic pathways were dramatically decreased, including folate biosynthesis, carbohydrate, lipid and amino acid pathways. Clinical examination of the hosts confirmed the identified metabolic changes, as demonstrated by decreased serum levels of haemoglobin and folic acid, a decreased neutrophil-to-lymphocyte ratio, and increased levels of triglycerides, cholesterol and homocysteine, which are consistent with the observed microbial variation. Our study suggests that oral mucosal bacteria may reflect host health conditions and could provide approaches for improving the health of sailors.

Cytological approach for diagnosis of non-healing oroantral fistula associated with candidiasis

Oroantral fistula (OAF) and oral candidiasis are common to come across as separate individual lesions. However when candida organisms infect maxillary sinus through OAF then diagnosis should not be limited to clinical diagnosis only. In such situation role of cytological examination can prove to be fruitful. A female with chronic long standing OAF, not responding to conventional treatment approach is reported. On incisional biopsy, the case was diagnosed as chronic maxillary sinusitis with OAF. However patient did not respond to any treatment approach and later presented with a more progressive lesion involving maxillary sinus. A cytosmear stained with periodic acid Schiff stain, revealed the presence of numerous candidal hyphae. Finally, case was diagnosed as OAF with a superadded candidal infection. Patient responded well to antifungal treatment followed by reclosure of OAF. We should not neglect a simple cytological examination which may prevent wrong diagnosis and wrong treatment.

Inhibitory effects of ameloblastin on epithelial cell proliferation

OBJECTIVE

Ameloblastin is an enamel matrix protein expressed in several tissues. Many potential mechanisms have been identified by which ameloblastin functions as an extracellular matrix protein. However, the biological effects of ameloblastin on gingival epithelial cells remain unclear. In the present study, we established a novel system to purify recombinant human ameloblastin and clarified its biological functions in epithelial cells in vitro.

DESIGN

Recombinant human ameloblastin was isolated from COS-7 cells overexpressing HaloTag-fused human ameloblastin by the HaloTag system and then purified further by reverse-phase high-performance liquid chromatography. SCC-25 cells, derived from human oral squamous cell carcinoma, were treated with recombinant ameloblastin and then cell survival was assessed by a WST-1 assay. Cell cycle analysis was performed by flow cytometry.

RESULTS

The novel purification system allowed effective recovery of the recombinant ameloblastin proteins at a high purity. Recombinant ameloblastin protein was found to suppress the proliferation of SCC-25 cells. Flow cytometric analysis showed that ameloblastin treatment induced cell cycle arrest G1 phase.

CONCLUSIONS

We developed a procedure for production of highly purified recombinant human ameloblastin. Biological analyses suggest that ameloblastin induces cell cycle arrest in epithelial cells and regulates the progression of periodontitis.

Whole cigarette smoke promotes human gingival epithelial cell apoptosis and inhibits cell repair processes

BACKGROUND AND OBJECTIVE

Smoking cigarettes increases the risk of developing various types of human diseases, including cancers and periodontitis. As gingival epithelial cells are known to play an active role in innate immunity via the secretion of a wide variety of mediators, and as these cells are the first ones exposed to environmental stimuli such as cigarette smoke, we sought to investigate the effects of whole cigarette smoke on normal human gingival epithelial cells and tissue.

MATERIAL AND METHODS

Human gingival epithelial cells were extracted from healthy nonsmokers and used either as a monolayer or as an engineered human oral mucosa to investigate the effect of whole cigarette smoke on cell growth, apoptosis and wound repair/migration.

RESULTS

Our findings show that when gingival epithelial cells were exposed once to whole cigarette smoke, this resulted in a significant inhibition of cell growth through an apoptotic pathway, as confirmed by an increase of Bax and a decrease of Bcl-xL and caspase-3 activity. Cigarette smoke also inhibited epithelial cell migration. These effects may explain the disorganization of the engineered human oral mucosa tissue when exposed to whole cigarette smoke.

CONCLUSION

Exposure to whole cigarette smoke markedly inhibits epithelial cell growth through an apoptosis/necrosis pathway that involves Bax and Bcl-xL proteins and caspase-3 activity. Cigarette smoke also disrupts epithelial cell migration, which may negatively affect periodontal wound healing.