Understanding the Pathobiology of Oral Lichen Planus

Single-cell immune profiling reveals immune responses in oral lichen planus

Introduction

Oral lichen planus (OLP) is a common chronic inflammatory disorder of the oral mucosa with an unclear etiology. Several types of immune cells are involved in the pathogenesis of OLP.

Methods

We used single-cell RNA sequencing and immune repertoire sequencing to characterize the mucosal immune microenvironment of OLP. The presence of tissue-resident memory CD8+ T cells are validated by multiplex immunofluorescence.

Results

We generated a transcriptome atlas from four OLP biopsy samples and their paired peripheral blood mononuclear cells (PBMCs), and compared them with two healthy tissues and three healthy PBMCs samples. Our analysis revealed activated tissue-resident memory CD8+ T cells in OLP tissues. T cell receptor repertoires displayed apperant clonal expansion and preferrential gene pairing in OLP patients. Additionally, obvious BCR clonal expansion was observed in OLP lesions. Plasmacytoid dendritic cells, a subtype that can promote dendritic cell maturation and enhance lymphocyte cytotoxicity, were identified in OLP. Conventional dendritic cells and macrophages are also found to exhibit pro-inflammatory activity in OLP. Cell-cell communication analysis reveals that fibroblasts might promote the recruitment and extravasation of immune cells into connective tissue.

Discussion

Our study provides insights into the immune ecosystem of OLP, serving as a valuable resource for precision diagnosis and therapy of OLP.

Assessing the Agreement of Light Microscopic Evaluation of Oral Lichen Planus Lesions With Associated Direct Immunofluorescence Evaluation

Aim/objective

Assess agreement between light microscopy and direct immunofluorescence (DIF) for histopathologic evaluation of oral lichen planus (OLP).

Methods

Records evaluated included 60 OLP, 16 lichenoid mucositis (LM), and 56 non-OLP/non-LM cases. Cases had both light microscopic and DIF evaluations. Histopathologic parameters of OLP included: (1) hydropic degeneration of the basal cell layer, (2) band-like lymphocytic infiltrate immediately subjacent to the epithelium, and (3) presence of Civatte bodies. Two calibrated examiners independently assessed light microscopic features. Examiners reviewed cases with discordant diagnoses to determine a consensus diagnosis. Intra-rater reliability (IRR), sensitivity, specificity, positive, and negative predictive values (PPV and NPV) were determined.

Results

Of 132 patients, 72.7% were female, average age 61.9 (SD = 13.8). Most common sites were gingiva (37.9%), buccal mucosa (37.1%), and tongue (7.6%). IRR was 0.74 (95% CI: 0.40, 1.00) for the consensus diagnosis and 0.73 (95% CI: 0.39, 1.00) and 0.34 (95% CI: -0.03, 0.72) for the 2 examiners. Comparing consensus and definitive diagnoses: sensitivity of light microscopy: 0.32 (95% CI: 0.20, 0.45); specificity: 0.88 (95% CI: 0.78, 0.94); PPV: 0.68 (95% CI: 0.48, 0.84), and NPV: 0.61 (95% CI: 0.51, 0.70).

Conclusion

Light microscopy alone is not a viable alternative to adjunctive DIF for diagnosis of OLP lesions.

Expression and Significance of TNF-α and NF-κB/p65 in Cutaneous Lichen Planus

Purpose

The purpose of this study was to explore the expression of TNF-α and NF-κB/p65 in Lichen planus skin lesions and their correlation with the pathogenesis of Lichen planus.

Patients and Methods

The case group consisted of 30 individuals diagnosed with LP based on clinical and histopathologic examination. The control group consisted of 10 individuals from an Orthopedic Department with normal skin. TNF-α and NF-κB/p65 expression in skin tissue samples was detected by immunohistochemistry.

Results

The immunohistochemical results showed that TNF-α and NF-κB/p65 expression levels were significantly higher in LP skin lesions than normal skin tissues (P ≤ 0.05). Positive TNF-α staining mainly occurred in the cytoplasm of keratinocytes of the stratum granulosum, stratum spinosum, and stratum basale in the epidermis and lymphocytes in the superficial dermis. Positive NF-κB/p65 staining mainly occurred in the nucleus and cytoplasm of keratinocytes of the stratum spinosum and stratum basale in the epidermis and lymphocytes in the superficial dermis.

Conclusion

TNF-α and NF-κB/p65 are overexpressed in cutaneous LP. The two are positively correlated in LP, suggesting that they both play essential roles in the pathogenesis of LP.

Salivary expression of lncRNA DQ786243 and IL-17 in oral lichen planus: case-control study

Background

A growing number of studies has investigated IL-17 in OLP. However, its exact role and interactions are not fully determined. In addition, the literature investigating its salivary expression is limited. The scarcity in the literature studying lncRNAs was noticed, particularly with regards to correlating them with cytokines in OLP. In the current study, the salivary expression of lncRNA DQ786243 and IL-17 was assessed among different forms of OLP.

Methods

The study included 52 participants in four equal groups: reticular OLP, erythematous OLP, ulcerative OLP, and control group. All eligible OLP patients underwent conventional oral examination, along with basic charting of their demographic data, pain intensity using a visual analogue scale, and clinical evaluation using the Thongprasom et al. scale. The salivary expression of lncRNA DQ786243 and IL-17 was evaluated for all participants using qRT-PCR. Unstimulated whole saliva samples were used. Data were analyzed for statistical significance.

Results

No statistically significant difference was observed when comparing the mean age and gender distribution of the studied groups. A statistically significant difference was detected when comparing pain and clinical scores in the three OLP forms. The highest expression of both salivary biomarkers was noticed in ulcerative OLP, followed by erythematous OLP and reticular OLP, then the controls, with a significant difference between the studied groups. Upon comparing the salivary expression of DQ786243 in ulcerative and erythematous OLP, no significant difference was detected. No significant difference was detected when comparing salivary expression of IL-17 in erythematous OLP to the other OLP forms.

Conclusions

The salivary expression of lncRNA DQ786243 and IL-17 was upregulated in OLP compared to healthy individuals. Besides, their expression increased when the severity of OLP was at its highest level in ulcerative OLP. There was a positive correlation between DQ786243 and IL-17.

Trial registration The protocol was registered at ClinicalTrials.gov (NCT04503824). The date of registration is 07/08/2020.

Clinical variability of recurrent oral HSV-1 infection with a high level of serum IgG antibody: Three case reports

Recurrent HSV-1 infection has various clinical features. This case report addresses three differences in the oral clinical manifestation of HSV-1 with the same high level of IgG titers reaching 200 U/mL. IgG antibody level indicates the state of recurrency but does not correlate with clinical features.

Analysis of the psychopathological profile, quality of life, and cost-effectiveness of oral lichen planus patients treated with photobiomodulation

OBJECTIVES

To evaluate the effect of PBM on the psychological profile and quality of life of patients with oral lichen planus (OLP) in comparison to corticoid and to investigate the cost-effectiveness of both treatments.

MATERIALS AND METHODS

Patients were randomized into two groups: Control (clobetasol propionate 0.05%) and Photobiomodulation (660 nm, 100mW, 177 J/cm², 5 s, 0.5 J) twice a week for 30 days. The Hospital Anxiety and Depression Scale (HADS) and OHIP-14 were used in different treatment time points and at follow-up. The cost-effectiveness was calculated using the improvement in OHIP-14 after treatment.

RESULTS

OLP patients showed detected levels of anxiety, depression, and poor quality of life at baseline. No improvement in anxiety and depression was noticed after treatments. However, PBM and corticoid significantly improved the quality of life of OLP patients, considering the OHIP-14-T and the physical pain domain. The treatment with corticoid was more cost-effective than PBM.

CONCLUSIONS

Psychological distress was not improved after both treatments and PBM is as effective as corticoids in promoting a better quality of life in OLP patients, despite its higher cost.

CLINICAL RELEVANCE

This study highlights the need for additional therapeutic interventions in OLP patients, to early recognize and to manage the alterations in their psychological profile. Moreover, PBM is an effective therapy in OLP patient's quality of live and although it was a more expensive, the advantage of being a minimally invasive therapy associated with no side effects must be considered in clinical practice, especially in those patients with refractory disease.

TRIAL REGISTRATION

This study is registered at ClinicalTrials.gov; the registration number is NCT03320460, registered in 17/10/2017.

The possible involvement of granulysin mediated cytotoxicity in keratinocytes disruption in lichen planus

Lichen planus is a chronic mucocutanous disorder histopathologically characterized with a keratinocytes apoptosis, subsequent basal cell layer liquefaction and accumulation of the inflammatory infiltrate in papillary dermis. A formation of apoptotic bodies in basal cell layer is due to a cytotoxic lymphocyte attack to the basal keratinocytes. It has been demonstrated that the cytotoxic molecules included in this attack are perforin and granzyme B. Both molecules are found upregulated in CD8+ lymphocytes that are in close contact to keratinocytes. However, their amount is lower in lichen planus than in other skin disease characterized by liquefaction and vacuolar degeneration of the basal epidermal layer. This could speculate about other cytotoxic molecule such as granulysin that could mediate keratinocyte apoptosis. Therefore, in this article we hypothesize about the crucial role of granulysin molecule in keratinocytes killing that could contribute to a lichen planus pathogenesis.

Roles of the matricellular protein Tenascin-C in T-lymphocyte trafficking and etiopathogenesis of Oral Lichen Planus

OBJECTIVE

This study was aimed at examining the role of Tenascin-C in T cell trafficking in Oral Lichen Planus (OLP).

DESIGN

For the in vivo immunohistochemical analyses, 115 OLP samples were collected from patients and immunostaining was performed. The intensity and distribution of TN-C expression were quantified and correlated with histological analyses of basement membrane integrity and presence of inflammatory infiltrate. For the in vitro study, TN-C and collagen were coated on culture plates and migration of T lymphocytes was assessed.

RESULTS

TN-C immunoexpression was increased in terms of both distribution and intensity along the basement membrane zone. These changes were significantly associated with basement membrane duplication (distribution p < 0.002 and intensity p < 0.001) and bands of inflammation (distribution p < 0.002 and intensity p < 0.001) assessed by Chi-square test. T lymphocytes demonstrated significant migration towards TN-C as compared to collagen (n = 3, p < 0.05).

CONCLUSIONS

These findings indicate TN-C may have a key role in promoting T cell migration at the epithelial-mesenchymal junction in OLP. These observations suggest TN-C could be a good target for therapeutic intervention, either in itself or synergistically with anti-inflammatory directed strategies in this chronic disease management.

Immunohistochemical Localization of RNase 7 in Normal and Inflamed Oral Epithelia and Salivary Glands

RNase 7 is a skin-derived antimicrobial peptide expressed in various epithelial tissues. It is upregulated by stimulation with microbes and pro-inflammatory cytokines. Herein, we examined the expression levels of RNase 7 in tissues from normal and inflamed oral epithelia and salivary glands via immunohistochemistry. RNase 7 was expressed mainly in the surface layers of the parakeratinized and orthokeratinized oral epithelium. In addition, it was strongly and weakly expressed in oral lichen planus and radicular cysts, respectively. RNase 7 was constitutively expressed in salivary glands, particularly in the serous and duct cells. In the case of Sjogren’s syndrome, RNase 7 was strongly expressed in serous, ductal, and mucous cells in areas with lymphocytic infiltration. The localization patterns of RNase 7 were similar to those of other epithelial antimicrobial peptides, including beta-defensins. Thus, epithelial antimicrobial peptides may act against microbial infections in a coordinated manner in oral epithelia and salivary glands.

Interferon gamma and interleukin 8 gene polymorphisms in patients with hepatitis C virus related oral lichen planus

OBJECTIVES

This study aimed to determine the association of rs2430561 and rs4073 polymorphisms in the Interferon gamma (IFN-ɤ) and Interleukin 8 (IL-8) genes, respectively, with hepatitis C virus-related oral lichen planus and disease severity.

DESIGN

This is a case-control study. 60 subjects were equally divided into patients with and without oral lichen planus. They were further subdivided into hepatitis C virus seropositive and seronegative patients. All patients were genotyped for IFN-γ rs2430561 thymine to adenine (T > A) and IL-8 rs4073 adenine to thymine (A > T) polymorphisms. All patients with oral lichen planus had their lesions measured and documented using the Escudier scoring system.

RESULTS

Disease activity was significantly higher in the "oral lichen planus/hepatitis C virus-positive" patients than in the "oral lichen planus/hepatitis C virus-negative" patients (P = 0.003). IFN-γ rs2430561 T > A and IL-8 rs4073 A > T genotypes and allele frequencies were not associated with the oral lichen planus group or the normal group. Stratification of the two groups into HCV and non-HCV-infected patients or into erosive and non-erosive types revealed no significant associations. The "A-allele-containing" genotypes of IL-8 rs4073 A > T were significantly more prevalent in the patients with oral lichen planus than in those without.

CONCLUSION

Hepatitis C virus infection is associated with the development of erosive oral lichen planus. The A-allele of IL-8 rs4073 A > T may have a role in the development and progression of oral lichen planus.

Association between TNFα - 308 G/A polymorphism and oral lichen planus (OLP): a meta-analysis

OBJECTIVES

To determine whether Tumor Necrosis Factor alpha (TNFα) -308 G/A polymorphism is associated with oral lichen planus (OLP).

MATERIAL AND METHODS

A systematic electronic search of the literature was conducted to identify all published studies on the association between TNFα -308 G/A polymorphism and OLP. All case-control studies evaluating the TNFα -308 G/A polymorphisms in OLP were selected. A meta-analysis of the studies that fulfilled the inclusion criteria was performed. Odds ratios (OR) with 95% confidence intervals (CI) were also calculated.

RESULTS

Seven studies comprising 450 OLP cases and 867 controls were included in the meta-analysis. In the pooled analysis, TNFα -308 G/A polymorphism was associated with OLP with random effects and OR of 2.33 (95%CI=1.07-5.11; p=0.03), assuming a dominant mode of inheritance (AA+GA vs. GG). In the subgroup analysis by ethnicity, TNFα -308 G/A was associated with a significantly increased odds ratio of OLP in mixed ethnicity (OR=5.22; 95%CI=1.93-14.15; p=0.001), but not in Asians (OR=1.57; 95%CI=0.54-4.54; p=0.41) or Caucasians (OR=1.45; 95%CI=0.19-11.22; p=0.72). For subgroup analysis based on HCV (hepatitis C virus) infection status, significant increased risk of OLP was found among patients with mixed HCV infection status (OR=3.77; 95%CI=1.07-13.2; p=0.038), but not in patients without HCV infection (OR=2.09; 95%CI=0.63-6.91; p=0.22) and patients with HCV infection (OR=0.48; 95%CI=0.13-1.69; p=0.25).

CONCLUSION

Our results suggest that -308 G/A polymorphism in TNFα is a potential genetic marker for OLP.

New evidence of connections between increased O-GlcNAcylation and inflammasome in the oral mucosa of patients with oral lichen planus

Oral lichen planus (OLP) is considered a chronic inflammatory immune-mediated disease of the oral mucosa. Immunopathogenesis of OLP is thought to be associated with cell-mediated immune dysregulation. O-GlcNAcylation is a form of reversible glycosylation. It has been demonstrated that O-GlcNAcylation promoted nuclear factor kappa B (NF-κB) signalling. Activation of NF-кB can induce expression of nucleotide-binding domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasome, which is a large intracellular multi-protein complex involving an immune response. Dysregulated expression of the NLRP3 inflammasome was reported to be associated with autoinflammatory diseases. No integrative studies between O-GlcNAcylation and NLRP3 inflammasome in OLP patients have been reported. The present study aimed to determine the immunohistochemical expression of O-GlcNAcylation, NF-κB signalling molecules and NLRP3 inflammasome in oral mucosae of OLP patients. Oral tissue samples were collected from 30 OLP patients and 30 healthy individuals. Immunohistochemical staining and analyses of immunostaining scores were performed to evaluate expression of O-GlcNAcylation, NF-κB signalling molecules and NLRP3 inflammasome. According to observations in this study, significantly higher levels of O-GlcNAcylation, NF-κB signalling molecules and NLRP3 inflammasome were demonstrated in OLP patients compared with control subjects (P < 0·001). Positive correlations among O-GlcNAcylation, NF-κB signalling molecules and NLRP3 inflammasome were also observed in OLP samples (P < 0·01). In conclusion, the present study provides supportive evidence that increased O-GlcNAcylation is associated with increased expression of NLRP3 inflammasome via the NF-κB signalling pathway. These findings provide a new perspective on immunopathogenesis of OLP in relation to autoinflammation.

Association of genetic polymorphisms in interferon-γ, interleukin-6 and transforming growth factor-β1 gene with oral lichen planus susceptibility

BACKGROUND

Oral lichen planus (OLP) is a premalignant mucocutaneous disease in which genetic factors and immune responses play a major role. Cytokines play an important role in the pathogenesis and disease progression of OLP. The aim of this study was to investigate the impact of gene polymorphisms of T helper cell subtype Th1 and Th2 cytokines, interferon-gamma (IFN-γ), interleukin-6 (IL-6) and transforming growth factor (TGF)-β1 on OLP susceptibility in a Saudi cohort.

METHODS

Forty two unrelated patients with OLP and 195 healthy controls were genotyped for IFN-γ (874A/T), IL-6 (174G/C) and TGF-β1 (509C/T) polymorphisms.

RESULTS

The frequency of genotype AT of IFN-γ (874A/T) was significantly higher while genotype AA was lower in OLP patients as compared to controls (P < 0.05). The frequency of T containing genotypes (AT + TT) was also higher in OLP patients as compared to that in controls (P = 0.003). The frequencies of allele T was higher while that of allele A lower in patients than the controls however the difference was not statistically significant (P = 0.07). There was no significant difference in the frequencies of alleles and genotypes of IL-6 (174G/C) and TGF-β1 (509C/T) polymorphisms between patient and control groups. These results indicated that genotype AT of IFN-γ (874A/T) polymorphism is associated with OLP risk and genotype AA is protective to OLP. On the other hand the polymorphisms IL-6 (174G/C) and TGF-β1 (509C/T) may not be associated with OLP risk in our population.

CONCLUSION

It is concluded that IFN-γ (874A/T) polymorphism is associated with the susceptibility of OLP, however further studies with large sample size involving different ethnic populations should be conducted to strengthen our results.

TNF-α, TNF-β and IL-10 gene polymorphism and association with oral lichen planus risk in Saudi patients

Objectives

Oral lichen planus (OLP) is a chronic inflammatory oral mucosal disease. Cytokines play an important role in the pathogenesis and disease progression of OLP. Various reports have implicated cytokine gene polymorphisms in susceptibility to develop some immune mediated conditions including OLP. The purpose of this study was to investigate the association of tumor necrosis factor (TNF)-α, TNF-β and interleukin (IL)-10 gene polymorphisms with the OLP risk.

Material and Methods

Forty two unrelated patients with OLP and 211 healthy volunteers were genotyped for TNF-α (-308 G/A), TNF-β (+252A/G), IL-10 (-1082G/A), IL-10 (-819C/T), and IL-10 (-592C/A) polymorphisms.

Results

The frequencies of allele A and genotype GA of TNF-α (-308G/A) were significantly higher while allele G and GG genotypes were lower in OLP patients as compared to the controls (P<0.001). The frequency of GA genotype of TNF-β (+252A/G) was significantly higher in patients than in controls while the AA genotype was completely absent in OLP patients. These results indicated that allele A and genotype GA of TNF-α (-308G/A) as well as the GA genotype of TNF-β (+252A/G) polymorphisms are associated with OLP risk. The frequencies of alleles and genotypes of -1082G/A, -819C/T and -592C/A polymorphisms in IL-10 gene did not differ significantly between OLP patients and controls (P>0.05). However, haplotype ATA extracted from 1082G/A, -819C/T, -592C/A polymorphisms of IL-10 were more prevalent in OLP patients when compared to controls indicating its possible association with OLP susceptibility.

Conclusion

It is concluded that TNF-α (-308G/A), TNF-β (+252A/G) and IL-10 (-1082G/A, -819C/T and -592C/A) polymorphisms are associated with the susceptibility of OLP, thus giving additional support for the genetic basis of this disease.