Mucosal microflora in head and neck cancer patients

Randomized Double-Blind Placebo-Controlled Study of Salivary Substitute with Enzymatic System for Xerostomia in Patients Irradiated in Head and Neck Region

This study aims to compare whether the use of a salivary substitute including an enzymatic system clinically reduces the intensity of xerostomia, as well as exploring the impact that this has on the quality of life, in patients who had received radiotherapy in the head and neck (HNC) region. Forty patients who had completed radiotherapy treatment within 6 months to 1 year previously were allocated into an Enzymatic Spray group (n = 21) or a Placebo arm (n = 19). It should be noted that two patients in the Placebo arm declined to participate during phase 2 of the study. All patients were randomized and used both products three times a day for 30 days. For analysis, xerostomia grade, unstimulated (UWS) and stimulated (SWS) salivary flow rate, and quality of life through the University of Washington Quality of Life Questionnaire validated in Portuguese (UW-QoL) were assessed in two phases: Phase 1 (before the use of the products) and Phase 2 (after 30 days of using the products). All clinical data were collected from medical records. Analyzing the salivary substitute with the enzymatic system, an improvement in xerostomia complaints was observed 30 days after using the product; however, this difference was not statistically significant (p > 0.05). Regarding quality of life, no significant differences were observed in relation to the UW-QoL and saliva domain between the groups in the two phases of the study (p > 0.05). The salivary substitute with the enzymatic system may be effective in reducing radio-induced xerostomia symptoms; however, further research is necessary to evaluate the efficacy of this salivary substitute on oral health.

Attempts to Understand Oral Mucositis in Head and Neck Cancer Patients through Omics Studies: A Narrative Review

Oral mucositis (OM) is a common and clinically impactful side effect of cytotoxic cancer treatment, particularly in patients with head and neck squamous cell carcinoma (HNSCC) who undergo radiotherapy with or without concomitant chemotherapy. The etiology and pathogenic mechanisms of OM are complex, multifaceted and elicit both direct and indirect damage to the mucosa. In this narrative review, we describe studies that use various omics methodologies (genomics, transcriptomics, microbiomics and metabolomics) in attempts to elucidate the biological pathways associated with the development or severity of OM. Integrating different omics into multi-omics approaches carries the potential to discover links among host factors (genomics), host responses (transcriptomics, metabolomics), and the local environment (microbiomics).

Antibacterial, antibiofilm and anticaries effect of BioXtra® mouthrinse for head and neck cancer (HNC) patients under a microcosm biofilm model

BACKGROUND AND PURPOSE

Considering the lack of studies investigating salivary substitutes to control post-radiation caries for patients with head and neck cancer (HNC), this study aimed to evaluate the antibacterial, antibiofilm, and anticaries effects of BioXtra® on the microcosm biofilm formed on different enamel types (non-irradiated and irradiated) and from distinct saliva sources (control and HNC patients).

MATERIALS AND METHODS

Non-irradiated and irradiated enamel specimens were treated with BioXtra®, phosphate-buffered-saline (PBS; negative control), or 0.12% chlorhexidine (CHX; positive control) for 1 min. Biofilm was produced from human saliva (healthy participants with normal salivary flow for the control group or irradiated HNC patients with hyposalivation for the HNC group), mixed with McBain saliva, under 0.2% sucrose exposure, daily submitted to the treatments (1 min), for 5 days. Bacterial metabolic activity, biofilm viability, CFU counting, and enamel demineralization were determined.

RESULTS

BioXtra® significantly reduced the bacterial metabolic activity for both enamel types and the inoculum sources, being more effective for the irradiated enamel or for the saliva from the control group. Similarly, BioXtra® significantly reduced the biofilm viability, the CFU for total microorganisms, mutans streptococci, and lactobacilli, and was able to significantly reduce the mineral loss and the lesion depth compared to PBS. CHX was an effective treatment to significantly reduce all parameters, performing better than BioXtra® and reinforcing its reliable efficiency as a positive control.

CONCLUSION

Regardless of the enamel type and the inoculum source, BioXtra® presented antibacterial, antibiofilm, and anticaries effects under this experimental model, which should be confirmed in further clinical studies.

Genomic sequence of the non-pathogen Neisseria sp. strain MA1-1 with antibiotic resistance and virulence factors isolated from a head and neck cancer patient

Recent research has claimed virulence factors or antimicrobial resistance in commensal or non-pathogenic Neisseria spp. This study aimed to isolate and analyze commensal microorganisms related to the genus Neisseria from the oral cavity of a patient with head and neck cancer. We successfully isolated strain MA1-1 and identified its functional gene contents. Although strain MA1-1 was related to Neisseria flava based on 16S rRNA gene sequence similarity, genomic relatedness analysis revealed that strain MA1-1 was closely related to Neisseria mucosa, reported as a commensal Neisseria species. The strain MA1-1 genome harbored genes for microaerobic respiration and the complete core metabolic pathway with few transporters for nutrients. A number of genes have been associated with virulence factors and resistance to various antibiotics. In addition, the comparative genomic analysis showed that most genes identified in the strain MA1-1 were shared with other Neisseria spp. including two well-known pathogens, Neisseria gonorrhoeae and Neisseria meningitidis. This indicates that the gene content of intra-members of the genus Neisseria has been evolutionarily conserved and is stable, with no gene recombination with other microbes in the host. Finally, this study provides more fundamental interpretations for the complete gene sequence of commensal Neisseria spp. and will contribute to advancing public health knowledge.

Effect of experimental and commercial artificial saliva formulations on the activity and viability of microcosm biofilm and on enamel demineralization for irradiated patients with head and neck cancer (HNC)

The effect of different artificial saliva formulations on biofilm activity and viability, and on enamel demineralization for head and neck cancer (HNC) patients was evaluated. Irradiated enamel samples were treated (1 min) with BioXtra® or with experimental formulations containing carboxymethylcellulose plus inorganic constituents alone (AS) or containing 0.1 mg mL^-1 CaneCPI-5 (AS + Cane), 1.0 mg mL^-1 hemoglobin (AS + Hb) or combination of both (AS + Cane + Hb). Phosphate-buffered-saline and chlorhexidine (0.12%) were negative and positive control, respectively. Biofilm was produced from the saliva of five male HNC patients, under 0.2% sucrose exposure for 5 days, and daily treated with the formulations (1 min). No significant effects were observed for the different experimental treatments. BioXtra^® significantly reduced lactobacilli, demonstrating antibacterial potential for this group. Chlorhexidine was an effective treatment to significantly reduce all parameters, being an important antimicrobial and anticaries agent. Future in vitro studies must be performed using a new approach for the design of the experimental formulations.

Oral Cavity and Candida albicans: Colonisation to the Development of Infection

Candida colonisation of the oral cavity increases in immunocompromised individuals which leads to the development of oral candidiasis. In addition, host factors such as xerostomia, smoking, oral prostheses, dental caries, diabetes and cancer treatment accelerate the disease process. Candida albicans is the primary causative agent of this infection, owing to its ability to form biofilm and hyphae and to produce hydrolytic enzymes and candialysin. Although mucosal immunity is activated, from the time hyphae-associated toxin is formed by the colonising C. albicans cells, an increased number and virulence of this pathogenic organism collectively leads to infection. Prevention of the development of infection can be achieved by addressing the host physiological factors and habits. For maintenance of oral health, conventional oral hygiene products containing antimicrobial compounds, essential oils and phytochemicals can be considered, these products can maintain the low number of Candida in the oral cavity and reduce their virulence. Vulnerable patients should be educated in order to increase compliance.

Stimulated saliva composition in patients with cancer of the head and neck region

BACKGROUND

To analyse over time changes in stimulated whole saliva regarding total protein, Immunoglobulin A (IgA), and mucin type O-glycans (mostly MUC5B and MUC7) in head and neck cancer patients.

METHODS

29 dentate patients (20 men and 9 women, 59 ± 8 years) treated with curative radiation therapy and chemotherapy for cancer of the head and neck region were included. The stimulated whole salivary secretion rate was determined and saliva collected at four time-points: at pretreatment, and at 6 months, 1 and 2 years post treatment. The total protein concentration was determined spectrophotometrically by using Bicinchoninic Acid assay and Immunoglobulin A (IgA) by using ELISA technique. Glycosylation pattern of salivary mucins was determined in samples collected pre- and post treatment by using LC/MS electrospray and mucin content quantified using SDS-AgPAGE gels and PAS staining.

RESULTS

Compared with pretreatment, the total protein concentration was increased already at 6 months post treatment (p < 0.01), and continued to increase up to 2 years post treatment (p < 0.001). During that period no significant changes in IgA concentration was detected. At pretreatment, the output/min of both total protein and IgA was significantly higher than at all time-points post treatment. Saliva from the cancer patients showed a low abundance/no detectable MUC7, while the MUC5B level remained, compared to saliva from a healthy control. The glycomic analysis showed that the percentage of core 2 O-glycans was increased as core 1, 3 and 4 O-glycans were decreased. The level of sialylation was higher at 6 months post treatment, while sulfation was lower.

CONCLUSION

A decreased output per minute of proteins at decreased salivary secretion rate, as well as reduced sulfation of MUC5B at 6 months post treatment tended to correlate with the patients' experience of sticky saliva and oral dryness. At 2 years post treatment, the decreased amount of IgA combined with a lowered salivary secretion rate indicate a reduced oral defense with increased risk of oral infections.

The interplay of the oral microbiome and alcohol consumption in oral squamous cell carcinomas

Oral cancer (OC) is among the top twenty occurring cancers in the world, with a mortality rate of 50%. A shift to a functionally inflammatory or a 'disease state' oral microbiome composition has been observed amongst patients with premalignant disorders and OC, with evidence suggesting alcohol could be exacerbating the inflammatory influence of the oral microorganisms. Alcohol dehydrogenase (ADH, EC 1.1.1.1) converts alcohol into a known carcinogenic metabolite, acetaldehyde and while ADH levels in oral mucosa are low, several oral commensal species possess ADH and could produce genotoxic levels of acetaldehyde. With a direct association between oral microbiome status, alcohol and poor oral health status combining to induce chronic inflammation with increased acetaldehyde levels - this leads to a tumour promoting environment. This new disease state increases the production of reactive oxygen species (ROS), while impairing anti-oxidant systems thus activating the redox signalling required for the promotion and survival of tumours. This review aims to highlight the evidence linking these processes in the progression of oral cancer.

Randomised, double-blind, placebo-controlled trial of oral probiotic Streptococcus salivarius M18 on head and neck cancer patients post-radiotherapy: a pilot study

Xerostomia detrimentally affects the oral health of many head and neck cancer patients who undergo radiotherapy. Its sequelae become an ongoing burden for patients that often manifest as periodontal disease and dental decay. Bacteria play a major role in the pathogenesis of these conditions and here we explore the use of an oral probiotic to beneficially modulate the oral bacterial community post-radiotherapy. In this pilot study, a four-week intervention with oral probiotic lozenges containing Streptococcus salivarius M18 was trialled in seven patients. Post-intervention changes in oral health and in the composition of the plaque and saliva bacterial communities were compared with six patients in a placebo group. An improvement in periodontal screening and plaque index scores was observed in both groups after the intervention period. The oral probiotic lozenges did not significantly impact bacterial community composition or diversity, nor did the probiotic lozenges increase the relative sequence abundance of ZOTU_1 (the probiotic-associated sequence assigned to S. salivarius) detected in the samples. Network analyses suggest negative interactions occurred between ZOTU_1 and species from the periopathogenic genera Campylobacter, Fretibacterium, Selenomonas and Treponema but further investigation is required to more fully understand the beneficial properties of this oral probiotic.

Oral microbial influences on oral mucositis during radiotherapy treatment of head and neck cancer

PURPOSE

Oral mucositis (OM) remains a significant complication developed by many patients undergoing radiotherapy (RT) to the head and neck region. Emerging data suggest oral microbes may contribute to the onset and severity of this acute side effect.

METHODS

In this study, saliva and oral swabs from head and neck cancer patients undergoing RT were collected. We employed molecular microbiological techniques to study the bacterial communities present in saliva, and both the bacterial and fungal communities present on the buccal mucosa and lateral tongue. Changes in microbiota composition with increasing radiation dose and the presence of mucositis were examined.

RESULTS

The data suggest that the salivary microbiota remain stable during RT and are consistently dominated by Streptococcus, Prevotella, Fusobacterium and Granulicatella. Obligate and facultative anaerobic Gram-negative bacilli (GNB) Bacteroidales G2, Capnocytophaga, Eikenella, Mycoplasma and Sneathia, as well as anaerobic GNB in the periopathogenic genera Porphyromonas and Tannerella, were all positively correlated with ≥ grade 2 OM. Significant increases in the relative abundances of Bacteroidales G2, Fusobacterium and Sneathia were identified in buccal mucosa swabs at sites of ≥ grade 2 OM (p < 0.05). Furthermore, the abundance of several GNB (Fusobacterium, Haemophilus, Tannerella, Porphyromonas and Eikenella) on the buccal mucosa may influence patient susceptibility to developing OM. Candida was widely detected in buccal mucosa swabs, regardless of mucositis status.

CONCLUSIONS

Our findings support previously hypothesized associations between oral health and the pathogenesis of OM, highlighting the importance of oral health interventions for head and neck cancer patients.

Staphylococcus aureus induces COX-2-dependent proliferation and malignant transformation in oral keratinocytes

The COX-2/PGE₂ axis can play roles in mediating the progression of tumor. COX-2 induction was observed in oral cancer. In our previous study, we found Staphylococcus aureus, a pathogen prevalent in oral cancer, can activate the COX-2/PGE₂ pathway in human oral keratinocyte (HOK) cells. Here, we investigated the proliferation of HOK cells affected by COX-2 induction and the role of COX-2 induction in the malignant transformation of HOK cells. We found S. aureus was able to facilitate HOK cell proliferation through upregulating COX-2 expression. With the induction of COX-2, expression of oral cancer-associated genes cyclin D1 was upregulated and p16 was downregulated. Transcriptome analysis showed that the “NF−kappa B signaling pathway” and “TNF signaling pathway” had the highest enrichment of differentially expressed genes (DEGs) with COX-2 over-expression. Seven upregulated genes (jun, tlr4, cxcl1, lif, cxcl3, tnfrsf1β, and il1β) in these two pathways were critical for the increased proliferation of HOK cells and might be associated with COX-2. Malignant transformation of cells was evaluated by soft agar colony formation assay and S. aureus infection promoted HOK cell colony formation. These results suggest the potential of S. aureus to induce the infection-associated malignant transformation of oral epitheliums through COX-2 activation.