Oral Microbiome Research on Oral Lichen Planus: Current Findings and Perspectives

Probiotics and prebiotics: new treatment strategies for oral potentially malignant disorders and gastrointestinal precancerous lesions

Oral potentially malignant disorders (OPMDs) and gastrointestinal precancerous lesions (GPLs) are major public health concerns because of their potential to progress to cancer. Probiotics, prebiotics, and engineered probiotics can positively influence the prevention and management of OPMDs and GPLs. This review aims to comprehensively review the application status of probiotics, prebiotics and engineered probiotics in OPMDs and GPLs, explore their potential mechanisms of action, and anticipate their future clinical use.

Alterations of oral microbiome and metabolic signatures and their interaction in oral lichen planus

Background

Oral lichen planus (OLP) is a chronic oral mucosal inflammatory disease with a risk of becoming malignant. Emerging evidence suggests that microbial imbalance plays an important role in the development of OLP. However, the association between the oral microbiota and the metabolic features in OLP is still unclear.

Methods

We conducted 16S rRNA sequencing and metabolomics profiling on 95 OLP patients and 105 healthy controls (HC).To study oral microbes and metabolic changes in OLP, we applied differential analysis, Spearman correlation analysis and four machine learning algoeithms.

Results

The alpha and beta diversity both differed between OLP and HC. After adjustment for gender and age, we found an increase in the relative abundance of Pseudomonas, Aggregatibacter, Campylobacter, and Lautropia in OLP, while 18 genera decreased in OLP. A total of 153 saliva metabolites distinguishing OLP from HC were identified. Notably, correlations were found between Oribacterium, specific lipid and amino acid metabolites, and OLP's clinical phenotype. Additionally, the combination of Pseudomonas, Rhodococcus and (±)10-HDoHE effectively distinguished OLP from HC.

Conclusions

Based on multi-omics data, this study provides comprehensive evidence of a novel interplay between oral microbiome and metabolome in OLP pathogenesis using the oral microbiota and metabolites of OLP patients.

Oral Lichen Planus: A Narrative Review Navigating Etiologies, Clinical Manifestations, Diagnostics, and Therapeutic Approaches

Background/Objectives: Oral Lichen Planus (OLP) is a common immune-mediated inflammatory disorder affecting the oral mucosa, impacting 0.5% to 2% of the global population, primarily middle-aged women. Immunological dysregulation is a key factor in OLP's pathogenesis, involving CD4+ T helper and CD8+ T cytotoxic cells. The World Health Organization (WHO) classifies OLP as a potentially malignant disorder, with a risk of oral squamous cell carcinoma (OSCC) developing in up to 2% of lesions. This narrative review aims to provide a comprehensive overview of the etiopathogenesis, clinical manifestations, diagnostic criteria, and therapeutic strategies for OLP, informing clinical practice and guiding future research. Methods: A review of the literature from the PubMed and Google Scholar databases was conducted up to December 2023, focusing on studies addressing the etiopathogenesis, diagnosis, clinical manifestations, and treatment of OLP. Results: OLP's pathogenesis is driven by immune dysregulation, with CD4+ and CD8+ cells playing crucial roles. Clinically, OLP presents as reticular, erosive, bullous, and plaque-like lesions. Diagnosis relies on clinical examination, histopathology, and direct immunofluorescence. Recent advancements in diagnostic markers and imaging techniques have improved detection and monitoring. Treatment primarily involves corticosteroids, but novel therapies such as curcumin, retinoids, and laser therapy are increasingly used for their effectiveness and reduced side effects. These treatments show promise in symptom reduction and recurrence prevention, although long-term data are needed. Conclusions: Regular screenings and biopsies are essential due to OLP's likelihood of malignant transformation. This study urges further investigation into long-term results, improved diagnostic techniques, and evidence-based treatment regimens.

Hepatitis C Virus (HCV) Infection: Pathogenesis, Oral Manifestations, and the Role of Direct-Acting Antiviral Therapy: A Narrative Review

Hepatitis C virus (HCV) infection is a global health concern with significant systemic implications, including a range of oral manifestations. This review aims to provide a comprehensive overview of the oral and dental pathologies related to HCV, the etiopathogenetic mechanisms linking such conditions to HCV and the impact of direct-acting antiviral (DAA) therapy. Common oral manifestations of HCV include oral lichen planus (OLP), periodontal disease, and xerostomia. The pathogenesis of these conditions involves both direct viral effects on oral tissues and indirect effects related to the immune response to HCV. Our literature analysis, using PubMed, Scopus, Web of Science, and Google Scholar, suggests that both the HCV infection and the immune response to HCV contribute to the increased prevalence of these oral diseases. The introduction of DAA therapy represents a significant advancement in HCV treatment, but its effects on oral manifestations, particularly OLP, are still under evaluation. Although a possible mechanism linking HCV to OSCC is yet to be determined, existing evidence encourages further investigation in this sense. Our findings highlight the need for established protocols for managing the oral health of patients with HCV, aiming to improve outcomes and quality of life.

The oral microbiome and oral and upper gastrointestinal diseases

Background

Microbiomes are essential components of the human body, and their populations are substantial. Under normal circumstances, microbiomes coexist harmoniously with the human body, but disturbances in this equilibrium can lead to various diseases. The oral microbiome is involved in the occurrence and development of many oral and gastrointestinal diseases. This review focuses on the relationship between oral microbiomes and oral and upper gastrointestinal diseases, and therapeutic strategies aiming to provide valuable insights for clinical prevention and treatment.

Methods

To identify relevant studies, we conducted searches in PubMed, Google Scholar, and Web of Science using keywords such as "oral microbiome," "oral flora, " "gastrointestinal disease, " without any date restrictions. Subsequently, the retrieved publications were subject to a narrative review.

Results

In this review, we found that oral microbiomes are closely related to oral and gastrointestinal diseases such as periodontitis, dental caries, reflux esophagitis, gastritis, and upper gastrointestinal tumors (mainly the malignant ones). Oral samples like saliva and buccal mucosa are not only easy to collect, but also display superior sample stability compared to gastrointestinal tissues. Consequently, analysis of the oral microbiome could potentially serve as an efficient preliminary screening method for high-risk groups before undergoing endoscopic examination. Besides, treatments based on the oral microbiomes could aid early diagnosis and treatment of these diseases.

Conclusions

Oral microbiomes are essential to oral and gastrointestinal diseases. Therapies centered on the oral microbiomes could facilitate the early detection and management of these conditions.

Microbial Profiles in Oral Lichen Planus: Comparisons with Healthy Controls and Erosive vs. Non-Erosive Subtypes

Recent studies have begun exploring the potential involvement of microbiota in the pathogenesis of oral lichen planus (OLP), yet comprehensive investigations remain limited. Hence, this study aimed to compare the microbial profiles in saliva samples obtained from patients with OLP against those from healthy controls (HC), along with a comparison between erosive (E) and non-erosive (NE) OLP patients. Saliva samples were collected from 60 OLP patients (E: n = 25, NE: n = 35) and 30 HC individuals. Analysis revealed no significant differences in alpha diversity, as assessed by the Chao1 and Shannon index, across the three groups. However, Bray-Curtis distance analysis indicated a significant disparity in microbiome composition distribution between HC and E-OLP, as well as HC and NE-OLP groups. The six most abundant phyla observed across the groups were Firmicutes, Bacteroidetes, Proteobacteria, Actinobacteria, Fusobacteria, and Saccharibacteria (TM7). Notably, OLP groups exhibited a higher prevalence of Bacteroidetes. Prevotella emerged as the predominant genus in the OLP groups, while Capnocytophaga showed a relatively higher prevalence in E-OLP compared to NE-OLP. This study's findings indicate a notable difference in microbiota composition between HC and patients with OLP. Additionally, differences in the microbiome were identified between the E-OLP and NE-OLP groups. The increase in the proportion of certain bacterial species in the oral microbiome suggests that they may exacerbate the inflammatory response and act as antigens for OLP.

Efficacy and safety of gut microbiota-based therapies in autoimmune and rheumatic diseases: a systematic review and meta-analysis of 80 randomized controlled trials

BACKGROUND

Previous randomized controlled trials (RCTs) suggested that gut microbiota-based therapies may be effective in treating autoimmune diseases, but a systematic summary is lacking.

METHODS

Pubmed, EMbase, Sinomed, and other databases were searched for RCTs related to the treatment of autoimmune diseases with probiotics from inception to June 2022. RevMan 5.4 software was used for meta-analysis after 2 investigators independently screened literature, extracted data, and assessed the risk of bias of included studies.

RESULTS

A total of 80 RCTs and 14 types of autoimmune disease [celiac sprue, SLE, and lupus nephritis (LN), RA, juvenile idiopathic arthritis (JIA), spondyloarthritis, psoriasis, fibromyalgia syndrome, MS, systemic sclerosis, type 1 diabetes mellitus (T1DM), oral lichen planus (OLP), Crohn's disease, ulcerative colitis] were included. The results showed that gut microbiota-based therapies may improve the symptoms and/or inflammatory factor of celiac sprue, SLE and LN, JIA, psoriasis, PSS, MS, systemic sclerosis, Crohn's disease, and ulcerative colitis. However, gut microbiota-based therapies may not improve the symptoms and/or inflammatory factor of spondyloarthritis and RA. Gut microbiota-based therapies may relieve the pain of fibromyalgia syndrome, but the effect on fibromyalgia impact questionnaire score is not significant. Gut microbiota-based therapies may improve HbA1c in T1DM, but its effect on total insulin requirement does not seem to be significant. These RCTs showed that probiotics did not increase the incidence of adverse events.

CONCLUSIONS

Gut microbiota-based therapies may improve several autoimmune diseases (celiac sprue, SLE and LN, JIA, psoriasis, fibromyalgia syndrome, PSS, MS, T1DM, Crohn's disease, and ulcerative colitis).

What can we learn from treatments of oral lichen planus?

Oral lichen planus (OLP), a T-lymphocyte-mediated disease of the oral mucosa, has a complex pathogenesis that involves a number of factors. The disease is characterized by recurrent episodes and requires continuous follow up, and there is no curative treatment available. Erosive lichen planus, among others, has a risk of malignant transformation and requires standardized treatment to control its progression. Different clinical subtypes of oral lichen planus require appropriate treatment. Pharmacological treatments are the most widely available and have the greatest variety of options and a number of novel pharmacological treatments are presented as highlights, including JAK enzyme inhibitors. The second is photodynamic therapy, which is the leading physiological treatment. In addition, periodontal treatment and psychological treatment should not be neglected. In this review, we briefly discuss the most recent developments in therapies for oral lichen planus after summarizing the most widely used clinical treatments, aiming to provide different proposals for future clinical treatment.

The Oral Microbiome across Oral Sites in Cats with Chronic Gingivostomatitis, Periodontal Disease, and Tooth Resorption Compared with Healthy Cats

Feline chronic gingivostomatitis (FCGS) is a chronic mucosal and gingival inflammatory disease in which pathogenesis remains unclear. Interactions between the host inflammatory process, the host immune response, and the oral microbiome are implicated in this pathogenesis. To begin to understand this disease and the impact of the microbiome to host inflammatory disease states, we collected sterile noninvasive plaque biofilm samples from ten distinct sites within the oral cavity in cats with stomatitis (n = 12), healthy cats (n = 9), and cats with tooth resorption or periodontitis (n = 11). Analysis of full-length 16S rRNA gene sequences indicated that the microbiomes of cats with FCGS presented marked dysbiosis at multiple oral sites. Additionally, microbiome beta diversity varied with oral condition, indicating that stomatitis, periodontitis, and/or tooth resorption influence the microbiome differently. Lastly, we found that the microbiomes of swabs taken from the oral cavity were comparable to those taken from plaque using endodontic paper points, validating this as another sampling method. Collectively, our work furthers our understanding of the dysbiosis and composition of bacteria in the oral microbiome in FCGS, with hopes of contributing to the prevention, diagnosis, and treatment of this challenging condition in felines.

Non-Coding RNAs as Potential Targets for Diagnosis and Treatment of Oral Lichen Planus: A Narrative Review

Oral lichen planus (OLP) is a chronic inflammatory disease that is characterized by the infiltration of T cells into the oral mucosa, causing the apoptosis of basal keratinocytes. OLP is a multifactorial disease of unknown etiology and is not solely caused by the malfunction of a single key gene but rather by various intracellular and extracellular factors. Non-coding RNAs play a critical role in immunological homeostasis and inflammatory response and are found in all cell types and bodily fluids, and their expression is closely regulated to preserve normal physiologies. The dysregulation of non-coding RNAs may be highly implicated in the onset and progression of diverse inflammatory disorders, including OLP. This narrative review summarizes the role of non-coding RNAs in molecular and cellular changes in the oral epithelium during OLP pathogenesis.

Effects of long-term metal exposure on the structure and co-occurrence patterns of the oral microbiota of residents around a mining area

Objectives

The aim of our study was to investigate the impact of long-term exposure to heavy metals on the microbiome of the buccal mucosa, to unveil the link between environmental contamination and the oral microbial ecosystem, and to comprehend its potential health implications.

Methods

Subjects were divided into two groups: the exposure group and the control group. We collected samples of buccal mucosa, soil, and blood, and conducted microbial diversity analysis on both groups of oral samples using 16S rRNA gene sequencing. The concentrations of heavy metals in blood and soil samples were also determined. Additionally, microbial networks were constructed for the purpose of topological analysis.

Results

Due to long-term exposure to heavy metals, the relative abundance of Rhodococcus, Delftia, Fusobacterium, and Peptostreptococcus increased, while the abundance of Streptococcus, Gemella, Prevotella, Granulicatella, and Porphyromonas decreased. The concentrations of heavy metals in the blood (Pb, Cd, Hg, and Mo) were associated with the growth of Rhodococcus, Delftia, Porphyromonas, and Gemella. In addition, the relative abundances of some pathogenic bacteria, such as Streptococcus anginosus, S. gordonii, and S. mutans, were found to be enriched in the exposure group. Compared to the exposure group network, the control group network had a greater number of nodes, modules, interactive species, and keystone taxa. Module hubs and connectors in the control group converted into peripherals in the exposure group, indicating that keystone taxa changed. Metals in the blood (Pb, Cd, Hg, and Mo) were drivers of the microbial network of the buccal mucosa, which can have adverse effects on the network, thus providing conditions for the occurrence of certain diseases.

Conclusion

Long-term exposure to multiple metals perturbs normal bacterial communities in the buccal mucosa of residents in contaminated areas. This exposure reduces the complexity and stability of the microbial network and increases the risk of developing various diseases.

Correlations between gut microbiota and lichen planus: a two-sample Mendelian randomization study

Purpose

Several existing studies have revealed that the occurrence of lichen planus (LP) is relevant to the gut microbiota, and the causal relationship between gut microbiota and LP was analyzed using the Mendelian randomization (MR) method.

Methods

Through the two-sample MR method, single nucleotide polymorphisms (SNPs) relevant to gut microbiota were selected as instrument variables (IVs) to evaluate the causal association between gut microbiota and the risk of LP.

Results

According to the selection criteria of inverse-variance weighted (IVW), six bacterial genera were found to be significantly linked to the initiation of LP; The IVW results suggested that Oxalobacteraceae, Victivallaceae, and Actinobacteria could restrain the initiation of LP, showing protective effects against LP. Desulfovibrio, Veillonella, and Ruminococcus gauvreauii groups were demonstrated to have casual correlations with the onset of LP.

Conclusion

The relationship between gut microbiota and LP was not a single positive or inverse relationship. Investigation of the causal relationship of these gut microbiota with LP could further provide evidence for the intestine-skin axis theory. However, the specific mechanism of microorganisms affecting the skin remains to be clarified. In this paper, the protective effects and mechanisms of Oxalobacteraceae, Victivallaceae, and Actinobacteria on LP require further exploration.

Immunological Aspects of EBV and Oral Mucosa Interactions in Oral Lichen Planus

Oral lichen planus (OLP) is considered a T cell-mediated chronic inflammatory process activated by an unknown antigen, making basal keratinocytes vulnerable to a cytotoxic cell mediated immune response. The aim of this review is to summarize information on the role and pathways of Epstein–Barr virus (EBV) and immune cells in inducing OLP as an autoimmune lesion. The pathogenesis of OLP is analyzed from immunological aspects of interactions between EBV and oral mucosa. The results of the available studies allow us to assume that EBV can act both as an exogenous and an endogenous antigen in the pathogenesis of OLP. We emphasized the role of antigen-presenting cells (APC), such as dendritic cells (Langerhans cells, LC), in detecting and capturing antigens and modulating the adaptive immune response. Although EBV shows tropism for B cells and epithelial cells, under certain conditions it can infect monocytes, LCs, NK, and T lymphocytes. It means that under some circumstances of the chronic inflammatory process, EBV particles can react as endogenous agents. During the development of the autoimmune process, a decisive role is played by the loss of immune tolerance. Factors like the activity of cytokines, chemokines, and autoantibodies secreted by EBV-positive plasma cells, autoantigens formed due to virus protein mimicry of human proteins, new self-peptides released from damaged tissues, self-reactive B and T cells, dysregulation of LC function, the anti-apoptotic effect of EBV early lytic antigens, and an imbalance between inflammatory and anti-inflammatory immune cells facilitate the development of an autoimmune process.

Research progress of single-cell transcriptome sequencing in autoimmune diseases and autoinflammatory disease: A review

Autoimmunity refers to the phenomenon that the body's immune system produces antibodies or sensitized lymphocytes to its own tissues to cause an immune response. Immune disorders caused by autoimmunity can mediate autoimmune diseases. Autoimmune diseases have complicated pathogenesis due to the many types of cells involved, and the mechanism is still unclear. The emergence of single-cell research technology can solve the problem that ordinary transcriptome technology cannot be accurate to cell type. It provides unbiased results through independent analysis of cells in tissues and provides more mRNA information for identifying cell subpopulations, which provides a novel approach to study disruption of immune tolerance and disturbance of pro-inflammatory pathways on a cellular basis. It may fundamentally change the understanding of molecular pathways in the pathogenesis of autoimmune diseases and develop targeted drugs. Single-cell transcriptome sequencing (scRNA-seq) has been widely applied in autoimmune diseases, which provides a powerful tool for demonstrating the cellular heterogeneity of tissues involved in various immune inflammations, identifying pathogenic cell populations, and revealing the mechanism of disease occurrence and development. This review describes the principles of scRNA-seq, introduces common sequencing platforms and practical procedures, and focuses on the progress of scRNA-seq in 41 autoimmune diseases, which include 9 systemic autoimmune diseases and autoinflammatory diseases (rheumatoid arthritis, systemic lupus erythematosus, etc.) and 32 organ-specific autoimmune diseases (5 Skin diseases, 3 Nervous system diseases, 4 Eye diseases, 2 Respiratory system diseases, 2 Circulatory system diseases, 6 Liver, Gallbladder and Pancreas diseases, 2 Gastrointestinal system diseases, 3 Muscle, Bones and joint diseases, 3 Urinary system diseases, 2 Reproductive system diseases). This review also prospects the molecular mechanism targets of autoimmune diseases from the multi-molecular level and multi-dimensional analysis combined with single-cell multi-omics sequencing technology (such as scRNA-seq, Single cell ATAC-seq and single cell immune group library sequencing), which provides a reference for further exploring the pathogenesis and marker screening of autoimmune diseases and autoimmune inflammatory diseases in the future.

Antioxidant therapy for patients with oral lichen planus: A systematic review and meta-analysis

Aims: This study aimed to systematically review the efficacy and safety of antioxidants for patients with Oral lichen planus (OLP). Methods: Databases, including PubMed, Web of Science, Cochrane Library, Embase, and Google Scholar, were searched up to 30 April 2022, for randomized controlled trials on the antioxidant therapy of OLP. The following endpoints were analyzed: pain score, clinical score, pain resolution rate, clinical resolution rate, and adverse effects. Results: A total of 19 studies met the inclusion criteria, and 17 studies with 704 patients were included in the meta-analysis. The findings showed that antioxidant therapy could significantly reduce the pain score [standardized mean difference -0.72 (-1.36, -0.07), P = 0.03, I2 = 87%, PI2 < 0.00001] and clinical score [SMD -2.06 (-3.06, -1.06), P < 0.0001, I2 = 94%, PI2 < 0.00001] of patients with OLP and improve the pain resolution rate [risk ratio (RR) 1.15 (1.01, 1.31), P = 0.04, I2 = 45%, PI2 = 0.09] and clinical resolution rate [RR 1.40 (1.10, 1.78), P = 0.006, I2 = 72%, PI2 = 0.002]. Conclusion: The study demonstrated that antioxidant therapy was beneficial for patients with OLP, and antioxidants might be used to treat OLP. Systematic Review Registration: https://clinicaltrials.gov/, identifier CRD4202233715.

Microbiome landscape of lesions and adjacent normal mucosal areas in oral lichen planus patient

The pathogenesis of oral lichen planus (OLP) remains unclear, and microbial dysbiosis has been proposed to play a role in the pathogenesis of OLP. Oral mucosal swabs from 77 OLP patients and 76 healthy subjects were collected. The bacterial community among the OLP lesion, the adjacent normal mucosal, and the oral mucosal surface in healthy people were analyzed by 16S sequencing. The factor of gender and age that may affect the flora distribution of OLP patients were explored. Results indicate no significant difference in microbiota between OLP and the adjacent group. Compared with the healthy group, Neisseria, Haemophilus, Fusobacterium, Porphyromonas, Rothia, Actinomyces, and Capnocytophaga significantly increased in the OLP group. Actinomyces increased in male OLP patients, and the other six bacteria increased in female OLP patients. In female OLP patients, Lautropia and Dialister were positively correlated with age. While in male OLP patients, Moraxella, Porphyromonas, and Fusobacterium were positively correlated with age. Functional enrichment analysis suggested that abnormal energy metabolism related to ATP synthases, abnormal transport and metabolism of glycans, amino acids, and vitamins, and disorders of the local immune microenvironment might exist in OLP lesion.