World Workshop on Oral Medicine VIII: Barriers to research in oral medicine: results from a global survey.

OBJECTIVES: To explore factors influencing research interest and productivity and perceived barriers to conducting research in Oral Medicine (OM). METHODS: Invitations to participate in an online survey were e-mailed to a network of international OM practitioners and related professional organizations. Questions captured respondents' demographic/professional variables and gauged research interest, productivity, and perceived barriers to conducting research specifically in OM. Statistical analysis was conducted via descriptive, logistic regression, and multivariate modeling. RESULTS: Five hundred and ninety-three OM practitioners from 55 countries completed the survey, with 54%, 25%, and 21% practicing in high, upper-middle, and lower-middle-income countries, respectively. Eighty-six percent of respondents were interested in conducting research. Age (less interest with an increase in age), working in academia, and practicing in a lower-middle vs high-income country were significant predictors of research interest. Self-reported research productivity was significantly greater among males, those working in academia, and those who graduated from programs that mandated research presentation/publication. Obtaining research funding was a significant barrier among respondents from lower and upper-middle-income countries, whereas finding time for research was a reported barrier by respondents from high-income countries. CONCLUSION: The results of this survey identified perceived barriers to conducting research in OM and highlighted solutions to address such barriers.

Topical clobetasol treatment for oral lichen planus can cause adrenal insufficiency.

OBJECTIVE: Glucocorticoids suppress the hypothalamic-pituitary-adrenal axis, which may lead to glucocorticoid-induced adrenal insufficiency. The study aimed to investigate the prevalence of this state in patients with oral lichen planus treated with topical clobetasol propionate. METHODS: In this cross-sectional study, 30 patients with oral lichen planus receiving long-term (>6 weeks) clobetasol propionate gel 0.025% were invited to participate. Adrenal function was assessed by measuring morning plasma cortisol after a 48-h withdrawal of clobetasol treatment. In patients with plasma cortisol <280 nmol/L, a cosyntropin stimulation test was performed. RESULTS: Twenty-seven patients were included. Twenty-one (78%) patients presented with plasma cortisol ≥280 nmol/L (range 280-570 nmol/L), and six (22%) <280 nmol/L (range 13-260 nmol/L). Five of these six patients underwent cosyntropin stimulation that revealed severe adrenal insufficiency in two patients (cortisol peak 150 nmol/L and 210 nmol/L) and mild adrenal insufficiency in three patients (cortisol peak 350-388 nmol/L). CONCLUSION: In this study, approximately 20% of patients receiving intermittent topical glucocorticoid treatment for oral lichen planus had glucocorticoid-induced adrenal insufficiency. It is essential for clinicians to be aware of this risk and to inform patients about the potential need for glucocorticoid stress doses during intercurrent illness.

Metataxonomic and metaproteomic profiling of the oral microbiome in oral lichen planus - a pilot study.

Background: A growing body of evidence demonstrates a different bacterial composition in the oral cavity of patients with oral lichen planus (OLP). Patients and methods: Buccal swab samples were collected from affected and non-affected sites of six patients with reticular OLP and the healthy oral mucosa of six control subjects. 16S rRNA gene MiSeq sequencing and mass spectrometry-based proteomics were utilised to identify the metataxonomic and metaproteomic profiles of the oral microbiome in both groups. Results: From the metataxonomic analysis, the most abundant species in the three subgroups were Streptococcus oralis and Pseudomonas aeruginosa, accounting for up to 70% of the total population. Principal Coordinates Analysis showed differential clustering of samples from the healthy and OLP groups. ANCOM-BC compositional analysis revealed multiple species (including P. aeruginosa and several species of Veillonella, Prevotella, Streptococcus and Neisseria) significantly over-represented in the control group and several (including Granulicatella elegans, Gemella haemolysans and G. parahaemolysans) in patients with OLP. The metaproteomic data were generally congruent and revealed that several Gemella haemolysans-belonging peptidases and other proteins with inflammatory and virulence potential were present in OLP lesions. Conclusion: Our data suggest that several bacterial species are associated with OLP. Future studies with larger cohorts should be conducted to determine their role in the aetiology of OLP and evaluate their potential as disease biomarkers.

A family-based genome-wide association study of recurrent aphthous stomatitis.

OBJECTIVES: The aetiology of recurrent aphthous stomatitis (RAS) remains unknown. Individuals may share features of genetic susceptibility, and there may also be a hereditary component. The aim was to identify patterns of association and segregation for genetic variants and to identify the genes and signalling pathways that determine the risk of developing RAS, through a family-based genome-wide association study (GWAS). SUBJECTS AND METHODS: DNA was extracted from buccal swabs of 91 individuals in 16 families and analysed in an Illumina core exome single nucleotide polymorphism (SNP) array. A family-based association test (dFAM) was used to derive SNP association values across all chromosomes. RESULTS: None of the final 288,452 SNPs reached the genome-wide significant threshold of 5 × 10-8 . The most significant pathways were the Ras and PI3K-Akt signalling pathways, pathways in cancer, circadian entrainment and the Rap 1 signalling pathway. CONCLUSIONS: This confirms that RAS is not monogenic but results as a consequence of interactions between multiple host genes and possibly also environmental factors. The present approach provides novel insights into the mechanisms underlying RAS and raises the possibility of identifying individuals at risk of acquiring this condition.

Lingual microbiota profiles of patients with geographic tongue.

Geographic tongue (GT) is an oral mucosal lesion that affects the tongue. The association between GT and the bacterial colonization profiles of the tongue is not clear. Lingual swabs were collected from lesion sites and healthy sites of 35 patients with GT (19 males and 16 females; Mage = 54.3 ± 16.1 years) and 22 controls (12 males and 10 females; Mage = 56.3 ± 15.8 years). Bacterial DNA was extracted and sequenced by next-generation sequencing. At the phylum level, Fusobacteria were significantly less abundant, while Spirochaetes were significantly more abundant in GT patients compared to controls. At the operational taxonomic units level, multivariate analysis revealed distinct clusters for the three groups based on the lingual microbiota composition. Acinetobacter and Delftia were significantly associated with GT lesion and healthy sites. However, Microbacterium, Leptospira, Methylotenera, and Lactococcus were significantly associated with GT lesion sites. Additionally, Mogibacterium and Simonsiella were significantly associated with GT healthy sites and controls. The changes in the lingual microbiota profiles of patients with GT imply a shift in the lingual bacterial ecology. However, it remains unknown if this shift is a consequence of the lesions or of factors associated with the initiation and progression of the disease.

The engagement of oral-associated lymphoid tissues during oral versus gastric antigen administration.

The role of oral-associated lymphoid tissues during induction of oral tolerance still remains elusive. Therefore, the aim was to compare T-cell activation and induction of tolerance to ovalbumin (OVA) presented through either of two routes; deposited into the oral cavity, or the stomach, thereby bypassing the oral cavity. OVA was administered by the oral or gastric route to BALB/c mice that had received OVA-specific DO11.10+ CD4(+) T cells, stained with CellTrace(™) Violet dye, through intravenous injection. Proliferating OVA-specific T cells were detected in the nose-associated lymphoid tissues (NALT) and the cervical, mesenteric and peripheral lymph nodes at different time-points following OVA exposure. OVA-specific T-cell proliferation was initially observed in the NALT 1 hr after oral, but not gastric, administration. However, at day 1, proliferation at this site was also detected after gastric administration and profound proliferation was observed at all sites by day 4. For the oral route the degree of proliferation observed was lower in the peripheral lymph nodes by day 4 compared with the other sites. These results demonstrate a similar activation pattern achieved by the two routes. However, the NALT distinguishes itself as a site of rapid T-cell activation towards fed antigens irrespective of feeding regimen. To evaluate induction of tolerance a semi-effective OVA dose was used, to detect differences in the degree of tolerance achieved. This was performed in a model of OVA-induced airway hypersensitivity. No differences in tolerance induction were observed between the two administration routes.

Salivary mucin MUC7 oligosaccharides in patients with recurrent aphthous stomatitis.

OBJECTIVES: The aetiology of recurrent aphthous stomatitis remains unknown. In this study, we investigate the composition of oligosaccharides from mucin MUC7 in recurrent aphthous stomatitis as these heavily O-glycosylated mucins confer many of saliva's protective properties such as defence against mucosal pathogens. MATERIALS AND METHODS: Unstimulated whole saliva samples were collected from six individuals, three with recurrent aphthous stomatitis and three corresponding sibling, without this condition. Oligosaccharides from salivary MUC7 were isolated and analysed by liquid chromatography-tandem mass spectrometry. RESULTS: The types of oligosaccharides identified in the patients and control subjects were similar; however, statistical evaluation indicated semi-quantitative differences between specific oligosaccharide classes. These changes focused on a reduction in terminal glycan residues including fucosylation, sialylation and sulfation on galactose. CONCLUSIONS: This study was able to show differential MUC7 glycosylation in the patients suggesting functional changes to salivary mucins in this condition. The terminal glycans altered in disease have been shown to be important for a range of immunological and bacterial binding roles. Further investigation of these epitopes in a larger study may provide critical insights into the pathology of recurrent aphthous stomatitis. CLINICAL RELEVANCE: MUC7 glycosylation is altered in recurrent aphthous stomatitis. This may change the protective properties of this mucin against mucosal pathogens, which may effect this condition.

The oral microbiota of patients with recurrent aphthous stomatitis.

BACKGROUND: Specific pathogenic bacteria have been implicated in recurrent aphthous stomatitis (RAS), a chronic inflammatory condition characterised by ulcerations in the oral mucosa. However, the aetiology behind this condition still remains unclear. OBJECTIVE: The buccal microbiota of patients with RAS was compared to that of control subjects to investigate its potential role for this condition. DESIGN: Buccal swabs were obtained from non-ulcerative areas of 60 patients, of whom 42 patients had lesions at the time of sampling, and 60 healthy age- and gender-matched controls. Bacterial DNA was extracted and analysed by Terminal-Restriction Fragment Length Polymorphism, using enzymatic digestion of the polymerase chain reaction-amplified 16S rRNA gene, yielding a series of peaks, each representing a bacterial taxon. RESULTS: Two peaks, 60 and 489, were more prevalent in patients with RAS than controls. Conversely, peaks 58 and 490 were less common in patients than controls. When the patients were divided into subgroups, we found that the observed differences in peak-pattern were related to the presence of lesions during sampling. CONCLUSIONS: The microbiota of the non-inflamed buccal mucosa differed between patients and controls. The differences were most pronounced in patients who presented with lesions during sampling, suggesting that a disturbance in the normal buccal microbiota triggers the presence of lesions or that presence of lesions alters the microbiota.