TLR2, TLR4 and CD86 gene polymorphisms in recurrent aphthous stomatitis

The Role of the Innate Immune Response in Oral Mucositis Pathogenesis

Oral mucositis (OM) is a significant complication of cancer therapy with limited management strategies. Whilst inflammation is a central feature of destructive and ultimately ulcerative pathology, to date, attempts to mitigate damage via this mechanism have proven limited. A relatively underexamined aspect of OM development is the contribution of elements of the innate immune system. In particular, the role played by barriers, pattern recognition systems, and microbial composition in early damage signaling requires further investigation. As such, this review highlights the innate immune response as a potential focus for research to better understand OM pathogenesis and development of interventions for patients treated with radiotherapy and chemotherapy. Future areas of evaluation include manipulation of microbial-mucosal interactions to alter cytotoxic sensitivity, use of germ-free models, and translation of innate immune-targeted agents interrogated for mucosal injury in other regions of the alimentary canal into OM-based clinical trials.

Roles of Toll-Like Receptors in Radiotherapy- and Chemotherapy-Induced Oral Mucositis: A Concise Review

Radiotherapy and/or chemotherapy-induced oral mucositis (RIOM/CIOM) is a common complication in cancer patients, leading to negative clinical manifestations, reduced quality of life, and impacting compliance with anticancer treatment. The composition and metabolic function of the oral microbiome, as well as the innate immune response of the oral mucosa are severely altered during chemotherapy or radiotherapy, promoting the expression of inflammatory mediators by direct and indirect mechanisms. Commensal oral bacteria-mediated innate immune signaling via Toll-like receptors (TLRs) ambiguously shapes radiotherapy- and/or chemotherapy-induced oral damage. To date, there has been no comprehensive overview of the role of TLRs in RIOM/CIOM. This review aims to provide a narrative of the involvement of TLRs, including TLR2, TLR4, TLR5, and TLR9, in RIOM/CIOM, mainly by mediating the interaction between the host and microorganisms. As such, we suggest that these TLR signaling pathways are a novel mechanism of RIOM/CIOM with considerable potential for use in therapeutic interventions. More studies are needed in the future to investigate the role of different TLRs in RIOM/CIOM to provide a reference for the precise control of RIOM/CIOM.

Occurrence of Recurrent Aphthous Stomatitis (RAS) as a Rare Oral Manifestation in a Patient with Gilbert's Syndrome

Recurrent aphthous stomatitis is an ulcerative disease of the oral cavity and can occur in isolation or as a manifestation of many systemic diseases. It is a quite common entity and may hence often be overlooked as an isolated lesion. Gilbert's syndrome is a genetic disorder where a deficiency of an enzyme associated with the conjugation of bilirubin results in unconjugated hyperbilirubinemia. The disease is generally asymptomatic and is aggravated by certain trigger factors. No associated oral manifestations are known. In this case report, we discuss the concomitant presence of recurrent aphthous stomatitis in a patient of Gilbert's syndrome. The presence of such recurrent stomatitis may represent as an oral manifestation of Gilbert's syndrome. Early identification of these entities may improve the overall quality of life of the patient.

Analysis of Interleukin-1 Receptor Antagonist Variable Number Tandem Repeat Variant in Recurrent Aphthous Stomatitis

BACKGROUND/AIMS

Recurrent aphthous stomatitis (RAS) is one of the common oral inflammatory diseases. As immunological and genetic factors have been held responsible for the pathogenesis of RAS, the objective of this study was to determine whether the interleukin-1 receptor antagonist (IL-1Ra) gene variable number tandem repeat (VNTR) variant is a risk factor for the development of RAS in Turkish patients and to define its contribution to the increased risk.

METHODS

The IL-1Ra VNTR variant was evaluated in 169 RAS patients and 171 healthy controls by the polymerase chain reaction (PCR) method.

RESULTS

No statistically significant difference was found in the genotype distributions and allele frequencies of IL-1Ra VNTR variant between RAS patients and healthy controls.

CONCLUSION

Lack of association between IL-1Ra VNTR variant and RAS could indicate that IL-1Ra has no significant role in the pathophysiology of RAS. However, it still appears to be very worthwhile to continue to search for cytokine gene variants in order to predict the development of such disease.

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.

Comparison of microbiomes in ulcerative and normal mucosa of recurrent aphthous stomatitis (RAS)-affected patients

BACKGROUND

Recurrent aphthous stomatitis (RAS) is the most common form of oral ulcerative disease, whose cause is still unknown. Researchers have found the association of many factors with the occurrence of RAS, and proposed oral bacterial infection could be a cause for this disease.

METHODS

To investigate whether the occurrence of RAS is associated with oral bacterial infection, we performed high throughput sequencing analysis of bacterial samples collected from the normal oral mucosa and aphthous ulcers of 24 patients.

RESULTS

Firmicutes, Proteobacteria and Bacteriodetes were the most abundant phyla in the microbiomes analysed. The alpha diversities of the oral mucosa and aphthous ulcer microbiomes were similar, suggesting a similar richness and diversity. The NMDS analysis showed the oral mucosa and aphthous ulcer microbiomes are significantly different. This suggestion is further supported by Anosim, MRPP, and Adonis analyses. More detailed comparison of the two groups of microbiomes suggested that the occurrence of RAS is significantly associated with the increase of Escherichia coli and Alloprevotella, as well as the decrease of Streptococcus.

CONCLUSIONS

Considering E. coli is a very common intestinal bacterium, we propose that E. coli colonization could be a cause for RAS, and controlling E. coli colonization could help curing RAS.

Recurrent oral ulceration: Etiology, classification, management, and diagnostic algorithm

Recurrent oral ulcerations are manifestations of a heterogeneous set of both general and more-or-less specific oral diseases due to numerous potential etiologies, including, but not limited to, infections, medications, autoimmune disease, and other systemic disease. This review discusses the pathogenesis, clinical presentation, diagnosis, and management of the common causes of recurrent oral ulceration. The following types/etiologies of recurrent oral ulceration are covered: traumatic ulceration, chemical ulceration, recurrent aphthous stomatitis, medication-related ulceration, infectious ulceration, mucocutaneous disease, and autoimmune/systemic disease. A diagnostic algorithm for recurrent oral ulceration is also presented.

Essentials of recurrent aphthous stomatitis

Recurrent aphthous stomatitis (RAS), also known as canker sores, is the most common disease of the oral mucosa. Unlike caries and periodontal disease, patients with RAS are unable to prevent it. The clinical picture of RAS is characterized by recurrent episodes of solitary or multiple painful ulcerations without association with systemic diseases. The objective of this review is to present the essential characteristics of RAS, including its definition, pathogenesis, clinical and microscopic characteristics, proposed experimental models and recommended pharmacological management. This understanding can serve as a theoretical framework for research proposals.

Interleukin-4 and Interleukin-4 Receptor Alpha Gene Polymorphisms in Recurrent Aphthous Stomatitis

BACKGROUND

Recurrent aphthous stomatitis (RAS) is a common oral condition with a major impact on the quality of life. The condition is thought to be due to the overexpression of T helper-1(Th1)-related cytokines. Since interleukin-4 (IL-4) and its receptor (IL-4Rα) are antagonistic to Th-1 pathways, polymorphisms in their genes may also be involved in the pathogenesis of aphthous stomatitis.

METHODS

Sixty-four patients diagnosed with minor RAS and 141 (age- and sex-matched) healthy controls were assessed for 3 single-nucleotide polymorphisms (SNPs) within the promoter region of the IL-4 gene (-1098G/T, -590C/T, and -33C/T), and 1 SNP in IL-4Rα gene (+1902 A/G).

RESULTS

No significant differences were detected between the patient and the control group regarding IL-4 allele frequencies. However, the patient group demonstrated a higher frequency of IL-4 -590 CC genotype and a lower rate of IL-4 -590 TC genotype. The TCT, GTT, GCT, and GTC haplotypes of the IL-4 gene (-1098, -590, -33) were significantly more frequent in the patients and the GCC, and TTT haplotypes were more common in healthy controls. No significant differences were found in IL-4Rα gene polymorphism between the 2 groups.

CONCLUSIONS

Certain polymorphisms of IL4 gene could predispose individuals to RAS.

Recurrent aphthous ulceration: a review of potential causes and novel treatments

Purpose of article: This review examines studies published between May 2012 and 2017 with a specific interest in potential recurrent aphthous ulceration (RAU) etiologies and treatment modalities/efficacy, including topical treatments, systemic regimens, vitamin repletion, and laser therapy, among others.

MATERIALS AND METHODS

PubMed MEDLINE and Cochrane Database of Systematic Reviews were searched using various combinations of: 'aphthous', 'ulcer', and 'treatment'. The titles and abstracts from the initial literature search were appraised to identify articles for full review and reference sections from each article were searched manually for relevant publications. Both randomized controlled trials and observational reports were included in this review, as some treatment types have not been formally examined in randomized trials. Relevant studies were reviewed, compared, and summarized.

RESULTS

RAU can result from systemic disease and trauma, but recent studies have shown a variety of potential etiologies, ranging from vitamin deficiencies, oral microbiota derangements, hematological considerations, stress, genetic polymorphisms to oxidant-antioxidant imbalances, among others. Many modalities of therapy are available and have proven efficacious.

CONCLUSIONS

As the exact etiology of RAU is still unknown, therapy is based on symptomatic relief.

Oral mucosal injury caused by mammalian target of rapamycin inhibitors: emerging perspectives on pathobiology and impact on clinical practice

In recent years oral mucosal injury has been increasingly recognized as an important toxicity associated with mammalian target of rapamycin (mTOR) inhibitors, including in patients with breast cancer who are receiving everolimus. This review addresses the state-of-the-science regarding mTOR inhibitor-associated stomatitis (mIAS), and delineates its clinical characteristics and management. Given the clinically impactful pain associated with mIAS, this review also specifically highlights new research focusing on the study of the molecular basis of pain. The incidence of mIAS varies widely (2-78%). As reported across multiple mTOR inhibitor clinical trials, grade 3/4 toxicity occurs in up to 9% of patients. Managing mTOR-associated oral lesions with topical oral, intralesional, and/or systemic steroids can be beneficial, in contrast to the lack of evidence supporting steroid treatment of oral mucositis caused by high-dose chemotherapy or radiation. However, steroid management is not uniformly efficacious in all patients receiving mTOR inhibitors. Furthermore, technology does not presently exist to permit clinicians to predict a priori which of their patients will develop these lesions. There thus remains a strategic need to define the pathobiology of mIAS, the molecular basis of pain, and risk prediction relative to development of the clinical lesion. This knowledge could lead to novel future interventions designed to more effectively prevent mIAS and improve pain management if clinically significant mIAS lesions develop.