Recent advances in the aetiology of recurrent aphthous stomatitis (RAS)

Emerging polymeric materials for treatment of oral diseases: design strategy towards a unique oral environment

Oral diseases are prevalent but challenging diseases owing to the highly movable and wet, microbial and inflammatory environment. Polymeric materials are regarded as one of the most promising biomaterials due to their good compatibility, facile preparation, and flexible design to obtain multifunctionality. Therefore, a variety of strategies have been employed to develop materials with improved therapeutic efficacy by overcoming physicobiological barriers in oral diseases. In this review, we summarize the design strategies of polymeric biomaterials for the treatment of oral diseases. First, we present the unique oral environment including highly movable and wet, microbial and inflammatory environment, which hinders the effective treatment of oral diseases. Second, a series of strategies for designing polymeric materials towards such a unique oral environment are highlighted. For example, multifunctional polymeric materials are armed with wet-adhesive, antimicrobial, and anti-inflammatory functions through advanced chemistry and nanotechnology to effectively treat oral diseases. These are achieved by designing wet-adhesive polymers modified with hydroxy, amine, quinone, and aldehyde groups to provide strong wet-adhesion through hydrogen and covalent bonding, and electrostatic and hydrophobic interactions, by developing antimicrobial polymers including cationic polymers, antimicrobial peptides, and antibiotic-conjugated polymers, and by synthesizing anti-inflammatory polymers with phenolic hydroxy and cysteine groups that function as immunomodulators and electron donors to reactive oxygen species to reduce inflammation. Third, various delivery systems with strong wet-adhesion and enhanced mucosa and biofilm penetration capabilities, such as nanoparticles, hydrogels, patches, and microneedles, are constructed for delivery of antibiotics, immunomodulators, and antioxidants to achieve therapeutic efficacy. Finally, we provide insights into challenges and future development of polymeric materials for oral diseases with promise for clinical translation.

Salivary microbiota and metabolic phenotype of patients with recurrent aphthous ulcers

OBJECTIVES

Recurrent aphthous ulcer (RAU) is a prevalent oral mucosal disease, affecting around 20% of the global population. It can greatly impair the quality of life for affected individuals. However, the exact etiology of RAU remains unknown.

SUBJECTS AND METHODS

16S rRNA sequencing (16S rRNA-seq) and non-targeted liquid chromatography-mass spectrometry (LC-MS) were employed to investigate the salivary microbiota and metabolic phenotype between RAU patients (N = 61) and healthy controls (HCs) (N = 105).

RESULTS

Findings from 16S rRNA -seq indicated reduced oral microbial diversity in RAU patients compared to HCs, but increased interactions. Clinical variables did not show any significant association with the overall diversity of oral microbiota in RAU patients. However, significant correlations were observed between specific microorganisms and clinical variables. LC-MS results revealed dysregulation of amino acid, lipid, nucleotide, and caffeine metabolism in RAU patients. Furthermore, correlation analysis of 16S rRNA-seq and LC-MS data revealed a significant association between salivary microbiota and metabolites in RAU patients.

CONCLUSIONS

Our study revealed notable differences in salivary microbiota and metabolic profiles between RAU patients and HCs, indicating a strong link between oral microbiota dysbiosis, metabolic disturbances, and the onset and progression of RAU.

Cardiovascular diseases, risk factors, and ulcer relapse in older adults with aphthous stomatitis

OBJECTIVES

To test the hypothesis that cardiovascular diseases and risk factors are associated with ulcer relapse in after-retirement patients with recurrent aphthous stomatitis.

SUBJECTS AND METHODS

This retrospective cohort study analyzed the data of 40 minor recurrent aphthous stomatitis patients aged 55-75 years, admitted to Oral Medicine Clinic at one university hospital in China between 2016 and 2018. The diagnosis of minor recurrent aphthous stomatitis was made based on the history and manifestation of oral ulcers. The ulcer relapse was evaluated after a 5-week anti-inflammatory treatment, and the history of systemic diseases was collected. cardiovascular disease/metabolic risk referred to the presence of any cardiovascular diseases and metabolic cardiovascular disease risks. Associations among cardiovascular diseases, risk factors, and ulcer relapse were evaluated.

RESULTS

The mean age of 40 patients with minor recurrent aphthous stomatitis was 62.4 years (SD 5.1), and 60% were women. The ulcer relapse rate was 37.5% (95% CI, 0.242-0.530). The proportion of cardiovascular disease/metabolic risk was higher in the relapse group than in the no-relapse group after 5-week anti-inflammatory treatment (Fisher's exact test, p = 0.041).

CONCLUSIONS

According to this single-center experience, older patients with cardiovascular disease/metabolic risk may be more prone to oral ulcer recurrence. Nevertheless, larger prospective studies are needed to confirm our findings.

Elevated serum fibrinogen levels in Chinese patients with minor recurrent aphthous stomatitis: An observational study

Fibrinogen is a protein that reflects systemic inflammation and regulates the immune response to disease. However, there is a scarcity of data on fibrinogen in recurrent aphthous stomatitis (RAS). We aimed to test the hypothesis that fibrinogen is involved in the aetiology of RAS. Between November 2016 and November 2018, we included 109 minor RAS patients and 29 age- and sex-matched controls in a single-center, observational study. Their clinical history and ulcer manifestations led to the diagnosis of minor RAS. The ulcer severity score (USS) was used to assess disease severity, and fibrinogen was also collected. We conducted three analyses: Analysis 1 (comparison of fibrinogen levels between patients and controls), Analysis 2 (comparison of fibrinogen levels between high and low USS patients) and Analysis 3 (comparison of fibrinogen levels between before and after anti-inflammatory treatment in patients). The fibrinogen levels in the 109 minor RAS patients were statistically higher than in the 29 controls (mean [SD], 2.6 [0.5] vs. 2.3 [0.3]; Student's t-test, p < 0.001). However, there were no significant differences in fibrinogen levels among the 43 patients with high USS and the 39 patients with low USS (mean [SD], 2.7 [0.5] vs. 2.6 [0.4]; Student's t-test, p = 0.278). Furthermore, fibrinogen levels were significantly higher before anti-inflammatory treatment in comparison to those after anti-inflammatory treatment in the 35 paired patients (mean [SD], 2.6 [0.4] vs. 2.5 [0.4]; Student's t-test, p = 0.026). Interestingly, fibrinogen levels were significantly higher in the 35 paired patients after anti-inflammatory treatment compared to the 29 control subjects (mean [SD], 2.5 [0.4] vs. 2.3 [0.3]; Student's t-test, p = 0.026]. Fibrinogen may play a role in the aetiology of RAS and may be a drug target for RAS treatment. Clinicians should be alert that high serum fibrinogen levels might be associated with the risk of RAS.

Determinants and inequality of recurrent aphthous stomatitis in an Indonesian population: a cross sectional study

INTRODUCTION

Recurrent Aphthous Stomatitis (RAS) is the most common type of ulceration in the oral cavity which can occur due to several factors.

AIMS

To determine the factors related to the incidence of RAS and examine the social class inequality in RAS among the Indonesian population using data from the fifth wave of the Indonesian Family Life Survey (IFLS5) in 2014.

METHODS

This study is a descriptive study with a cross-sectional design using secondary data from IFLS5 data in 2014 (n = 28,410). Socio-economic position (SEP) was calculated by Adult Equivalent Scale and categorized into 4 classes. Outcome is RAS. Mediating factors were psychosocial (stress), eating behavioral (food consumption), and systemic diseases. Descriptive analysis, chi-square and a series of logistic regressions were performed to analyze the data. Odds ratio (OR) and 95% confidence interval (CI) were used to report the results.

RESULTS

Only 18.39% of IFLS5 respondents experienced the incidence of recurrent aphthous stomatitis in 2014. The bivariate (chi-square) results showed that there was a relationship between the incidence of RAS and the related independent variables. Logistic regression showed the highest possibility of RAS in respondents aged 18-34 years, female, unmarried, high school education level, living in the city, having frequent stress levels, having food habits that frequently drinking soda, sweet foods, chili sauce, fried food and has systemic diseases such as, asthma, cancer, rheumatism, and digestion. The lowest SEP group had the highest probability of occurrence of RAS over the other groups among the different models.

CONCLUSIONS

There are several factors that determine the incidence of RAS. There was a monotonic gradient of inequality in RAS according to SEP group. This study might be useful to provide information regarding the relationship of determinants factors with the incidence of RAS to prevent it and promote oral health in the future.

[Recurrent aphthous stomatitis]

Recurrent aphthous stomatitis (RAS) is the most common clinical disease of the oral mucosa. Its prevalence in the general population varies between 5 and 25%, with its peak appearance in the second decade of life. So far, the etiopathogenesis is not clear. In genetically predisposed patients, the effect of certain triggering factors would initiate the proinflammatory cytokine cascade directed against certain regions of the oral mucosa. Ulcers are round or oval with well-defined erythematous margins and a shallow ulcerated center covered with a gray or yellowish fibrinous pseudomembrane. The ulcers may reappear at intervals of a few days and months. Given the appearance of periodic thrush in the oral mucosa, the first thing to do is to make a correct differential diagnosis, rule out associated systemic diseases and assess treatable causes before reaching the diagnosis of RAS. At present, there is no curative treatment.

Efficacy and safety of total glucosides of paeony in the treatment of recurrent aphthous ulcers: a single-center, double-blind, randomized, placebo-controlled clinical trial

Introduction: There has been a lack of treatments available to lower the frequency of recurrent aphthous ulcers (RAUs) until now. Total glucosides of paeony (TGP) is a botanical drug extracted from the dried roots of Paeonia lactiflora Pall. [Ranunculaceae; Paeoniae Radix Alba]. This study aims to evaluate the efficacy and safety of TGP in the treatment of RAU. Methods: This study was registered with the Chinese Clinical Trial Registry (ChiCTR1900025623). Patients were randomly assigned to the TGP or placebo group and treated with 1.8 g/day for 24 weeks. Participants were observed for a total of 36 weeks and were asked to record ulcer severity, medication, and adverse reactions in the form of diaries or apps every day. The primary outcome was the monthly ulcer-free interval. Results: A total of 79 individuals were enrolled, with 40 assigned to the TGP group and 39 to the placebo group. The dropout rate was 18.18%. In the TGP group, the monthly ulcer-free interval was significantly longer than baseline (median, 9.6 days) since weeks 13-24 (median, 18.5 days) (p < 0.05), and after discontinuation, it was further prolonged (median, 24.7 days) than in weeks 13-24 (p < 0.05). In addition, the monthly ulcer-free interval was longer in the TGP group than in the placebo group (median, 15.9 days) at weeks 25-36 (p < 0.001). There were better improvements in the monthly number of ulcers and monthly area of ulcers, and visual analog scoring in the TGP group at weeks 25-36 (p < 0.001). Conclusion: TGP had a good long-term therapeutic effect on RAU with frequent occurrence. Systematic Review Registration: www.chictr.org.cn, identifier ChiCTR1900025623.

Expression of Salivary Ceramide Synthase 1 (CERS1) in Recurrent Aphthous Stomatitis (RAS): A Cross-Sectional Institutional Study

Background The increased rate of apoptosis is one of the major causes of ulcer formation. A variety of factors can influence the rate of apoptosis. Ceramide (CER) is one such factor that has been proposed to play a role in signaling apoptosis induced by extracellular agents. Recurrent aphthous stomatitis (RAS) is a common condition that initially presents in children or adolescents. Multiple recurrent small, round, or ovoid ulcers with erythematous haloes and circumscribed margins are its characteristic features. Its pathogenesis is still a mystery. Ceramide synthase 1 (CERS1) aids in the production of C18 CER. Although the role of CERS1 in aphthous is well understood, its possible intricate role in pathogenesis remains unknown. Aim To evaluate the expression of salivary CERS1 in patients with RAS and healthy individuals. Materials and methods 30 patients were included in the present study. Ethical clearance for this study was obtained, and there were no gender or age limits for enrollment. After obtaining informed consent, 30 salivary samples were collected from patients with RAS (n=15) and from healthy individuals (n=15). Enzyme-linked immunosorbent assay (ELISA) was performed using the CERS1 kit by MyBioSource Inc (San Diego, USA) and the results were recorded. The Chi-square test and Independent t-test were used for statistical analysis with SPSS v23.0 (IBM, Chicago, USA) with a significant p-value of <0.05. Results CERS1 expression was identified in the saliva of all participants. There was a decrease in the salivary CERS1 level in RAS patients (7.6 +/- 2.0 pg/ml) when compared to healthy individuals (8.3 +/- 1.8 pg/ml) but it did not achieve statistical significance. Conclusion We found that salivary CERS1 levels decreased in RAS patients. More research is required to understand CERS1's pathogenetic role.

Soluble epoxide hydrolase inhibitor promotes the healing of oral ulcers

OBJECTIVE

Oral ulcers are a lesion in the oral mucosa that impacts chewing or drinking. Epoxyeicosatrienoic Acids (EETs) have enhanced angiogenic, regenerative, anti-inflammatory, and analgesic effects. The present study aims to evaluate the effects of 1-Trifluoromethoxyphenyl-3-(1-Propionylpiperidin-4-yl) Urea (TPPU), a soluble epoxide hydrolase inhibitor for increasing EETs level, on the healing of oral ulcers.

METHODS

The chemically-induced oral ulcers were established in Sprague Dawley rats. The ulcer area was treated with TPPU to evaluate the healing time and pain threshold of ulcers. The expression of angiogenesis and cell proliferation-related protein in the ulcer area was detected using immunohistochemical staining. The effects of TPPU on migration and angiogenesis capability were measured with scratch assay and tube formation.

RESULTS

Compared with the control group, TPPU promoted wound healing of oral ulcers with a shorter healing time, and raised pain thresholds. Immunohistochemical staining showed that TPPU increased the expression of angiogenesis and cell proliferation-related protein with reduced inflammatory cell infiltration in the ulcer area. TPPU enhanced cell migration and tube-forming potential in vitro.

CONCLUSIONS

The present results support the potential of TPPU with multiple biological effects for the treatment of oral ulcers by targeting soluble epoxide hydrolase.