Expression of T-bet and GATA-3 in peripheral blood mononuclear cells of patients with oral lichen planus

Function of unconventional T cells in oral lichen planus revealed by single-cell RNA sequencing

OBJECTIVE

We intended to map the single-cell profile of OLP, explore the molecular characteristics of unconventional T cells in OLP tissues.

METHODS

Buccal mucosa samples from OLP patients and healthy individuals were used to prepare single-cell suspension. Single-cell RNA sequencing was used to analyze the proportion of all the cells, and the molecular characteristics of unconventional T cells. Immunohistochemical staining was used to detect the expression of unconventional T cells marker genes.

RESULTS

The cell clusters from buccal mucosa were categorized into immune cells, fibroblasts, endothelial cells, and epithelial cells. Unconventional T cells with phenotype of CD247+TRDC+NCAM1+ were identified. Immunohistochemical staining revealed higher expression of unconventional T cell marker genes in OLP tissue, predominantly in the lamina propria. In OLP, unconventional T cells are in a unique stress response state, exhibited enhanced NF-κB signaling and apoptosis inhibition, enhanced heat shock protein genes expression, weakened cytotoxic function. A large number of ligand-receptor pairs were found between unconventional T cells and other cells, particularly with fibroblasts and endothelial cells.

CONCLUSIONS

This study mapped the single-cell profile of OLP, delineated the molecular characteristics of unconventional T cells in OLP, and uncovered that these unconventional T cells are in a stress response state.

MALT1 Protease Regulates T-Cell Immunity via the mTOR Pathway in Oral Lichen Planus

Oral lichen planus (OLP) is a T cell-mediated immune mucosal disease of unknown pathogenesis. Whether mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1), an intracellular signaling protein, is involved in the T-cell immune dysfunction of OLP remains elusive. MALT1 expression in local and peripheral T cells of OLP and controls was analyzed using immunohistochemistry, multiplex immunohistochemistry, and flow cytometry. The expression of MALT1 in activated Jurkat T cells incubated with either OLP plasma or interleukin (IL)-7/IL-15 was determined by flow cytometry. The effects of MALT1 and mechanistic target of rapamycin (mTOR) on T-cell immunity were investigated through western blot, CCK8 assay, and flow cytometry. The expression of MALT1 protein was elevated in local OLP T cells and mucosal-associated invariant T (MAIT) cells, while reduced in peripheral OLP T cells, MAIT cells, and follicular helper-like MAIT (MAITfh) cells. Stimulation with OLP plasma and IL-7/ IL-15 had no effect on MALT1 expression in activated Jurkat T cells. MALT1 protease-specific inhibitor (MI-2) induced mTOR phosphorylation, increased B-cell lymphoma 10 (BCL10) expression, inhibited T-cell proliferation, and promoted T-cell apoptosis. The combination of MI-2 and rapamycin increased MALT1 expression, further suppressed T-cell proliferation, and facilitated T-cell apoptosis. MALT1 expression is aberrant in both local lesions and peripheral blood of OLP. Inhibition of the mTOR pathway further enhances the suppression of T-cell proliferation and the promotion of apoptosis induced by the MALT1 inhibitor MI-2.

Upregulation of IL-37 in epithelial cells: A potential new mechanism of T cell inhibition induced by tacrolimus

Oral lichen planus (OLP) is a chronic T cell-mediated mucocutaneous disease characterized by T cell infiltration at the connective tissue-epithelium interface. Traditionally, topical corticosteroids are used as the first-line drugs to treat OLP. However, long-term use of corticosteroids may lead to drug tolerance, secondary candidiasis, and autoimmune adrenal insufficiency. Although topical tacrolimus has often been recommended for short-term use in corticosteroid-refractory OLP, the precise role of tacrolimus in epithelial cells remains elusive. This study showed that tacrolimus could directly upregulate the expression of IL-37 in human gingival epithelial cells by promoting the TGF-βRI/Smad3 pathway independently of calcineurin inhibition and MAPKs. In contrast, dexamethasone, one of the corticosteroids, did not have the same effect. Moreover, IL-37 could inhibit the proliferation of activated T cells and the secretion of effector cytokines and alleviate epithelial cell apoptosis and death caused by activated T cells ina co-culturesystem. Furthermore, compared with healthy controls, IL-37 and p-Smad3 levels significantly increased in the oral mucosa affected by OLP, especially in the epithelium. IL-37 might have mediated a negative feedback mechanism to curb excessive inflammation in OLP. However, the expression of IL-37 was not associated with the infiltration of CD8+ T cells and Tregs in OLP, implying that IL-37 might mostly affect T cell activation rather than T cell differentiation and migration. Overall, this study discovered a potential novel mechanism by which tacrolimus might indirectly inhibit T cell-mediated immune damage by upregulating IL-37 in human gingival epithelial cells.

ASCT2-mediated glutamine uptake promotes Th1 differentiation via ROS-EGR1-PAC1 pathway in oral lichen planus

Oral lichen planus (OLP) is a T cell-mediated autoimmune disease of oral mucosa concerning with the redox imbalance. Although glutamine uptake mediated by alanine-serine-cysteine transporter 2 (ASCT2) is critical to T cell differentiation, the exact mechanism remains ambiguous. Here, we elucidate a novel regulatory mechanism of ASCT2-mediated uptake in the differentiation and proliferation of T cells through maintaining redox balance in OLP. The results of immunohistochemistry (IHC) showed that both ASCT2 and glutaminase (GLS) were obviously upregulated compared to controls in OLP. Moreover, correlation analyses indicated that ASCT2 expression was significantly related to GLS level. Interestingly, the upregulation of glutamine metabolism in epithelial layer was consistent with that in lamina propria. Functional assays in vitro revealed the positive association between glutamine metabolism and lymphocytes infiltration. Additionally, multiplex immunohistochemistry (mIHC) uncovered a stronger colocalization among ASCT2 and CD4 and IFN-γ, which was further demonstrated by human Th1 differentiation assay in vitro. Mechanistically, targeting glutamine uptake through interference with ASCT2 using L-γ-Glutamyl-p-nitroanilide (GPNA) decreased the glutamine uptake of T cells and leaded to the accumulation of intracellular reactive oxygen species (ROS), which promoted dual specificity phosphatase 2 (DUSP2/PAC1) expression through activation of early growth response 1 (EGR1) to induce dephosphorylation of signal transducer and activator of transcription 3 (STAT3) and inhibit Th1 differentiation in turn. These results demonstrated that glutamine uptake mediated by ASCT2 induced Th1 differentiation by ROS-EGR1-PAC1 pathway, and restoring the redox dynamic balance through targeting ASCT2 may be a potential treatment for T cell-mediated autoimmune diseases.

Predicting the Activity of Oral Lichen Planus with Glycolysis-related Molecules: A Scikit-learn-based Function

OBJECTIVE

Oral lichen planus (OLP) is one of the most common oral mucosa diseases, and is mainly mediated by T lymphocytes. The metabolic reprogramming of activated T cells has been shown to transform from oxidative phosphorylation to aerobic glycolysis. The present study investigated the serum levels of glycolysis-related molecules (lactate dehydrogenase, LDH; pyruvic acid, PA; lactic acid, LAC) in OLP, and the correlation with OLP activity was assessed using the reticular, atrophic and erosive lesion (RAE) scoring system.

METHODS

Univariate and multivariate linear regression functions based on scikit-learn were designed to predict the RAE scores in OLP patients, and the performance of these two machine learning functions was compared.

RESULTS

The results revealed that the serum levels of PA and LAC were upregulated in erosive OLP (EOLP) patients, when compared to healthy volunteers. Furthermore, the LDH and LAC levels were significantly higher in the EOLP group than in the nonerosive OLP (NEOLP) group. All glycolysis-related molecules were positively correlated to the RAE scores. Among these, LAC had a strong correlation. The univariate function that involved the LAC level and the multivariate function that involved all glycolysis-related molecules presented comparable prediction accuracy and stability, but the latter was more time-consuming.

CONCLUSION

It can be concluded that the serum LAC level can be a user-friendly biomarker to monitor the OLP activity, based on the univariate function developed in the present study. The intervention of the glycolytic pathway may provide a potential therapeutic strategy.

Autophagy-related 9 homolog B regulates T-cell-mediated immune responses in oral lichen planus

OBJECTIVES

This study aimed to explore the impacts of autophagy-related 9 homolog B (ATG9B)-mediated autophagy on T-cell immune responses in oral lichen planus.

DESIGN

ATG9B expression was detected in lesions and local T cells by immunohistochemical analysis and immunofluorescence assay. The effects of ATG9B-mediated autophagy on T-cell immune responses were explored after ATG9B-overexpression or ATG9B-knockdown lentivirus transfection. A coculture system of activated T cells and lipopolysaccharide-induced keratinocytes was used to simulate the main cell crosstalk in oral lichen planus.

RESULTS

The expression of ATG9B upregulated in lesions and local T cells of oral lichen planus, especially in non-erosive oral lichen planus, suggesting that ATG9B may be a diagnostic factor for oral lichen planus. Notably, ATG9B-knockdown T cells of oral lichen planus demonstrated autophagy suppression, enhanced proliferation, and attenuated apoptosis, whereas overexpression of ATG9B showed opposite effects on T cells. In the coculture system of T cells and keratinocytes, ATG9B-knockdown T cells of oral lichen planus, but not ATG9B-overexpression T cells, promoted the proliferation and apoptosis of their cocultured keratinocytes. Additionally, exogenous insulin-like growth factor 1 (IGF1) significantly reversed the apoptosis rates of keratinocytes cocultured with T cells expressing abnormal ATG9B. Furthermore, ATG9B-overexpression T cells showed decreased secretion of interferon-γ and tumor necrosis factor-α in the coculture system.

CONCLUSIONS

This study revealed the regulatory roles of ATG9B-mediated T-cell autophagy on T-cell immune responses and crosstalk between T cells and keratinocytes in of oral lichen planus.

MAIT cells and their implication in human oral diseases

OBJECTIVE

Mucosal-associated invariant T (MAIT) cells are unique innate-like T cells that are abundant in humans, accounting for 1-10% of circulating T cells and about 2% of total T cells in human oral cavity. MAIT cells can mount a strong immune response quickly without exogenous antigens and undergo a phenotypic transformation in the development of diseases. They produce cytokines involved in the Th1 and Th17 immune response and cytotoxic proteins, promote the dysfunction of autoreactive B cell and inhibit the function of NK cells. MAIT cells have been widely explored in autoimmune diseases, inflammatory diseases and tumors, and these mechanisms may also be involved in the pathogenesis of some oral diseases, while MAIT cells have not been systematically discussed in oral diseases.

METHODS

We searched PubMed/MEDLINE, EMBASE and Microsoft Bing databases to review and analyze relevant literatures on the impact of MAIT cells in the pathogenesis of human oral diseases.

CONCLUSION

Collected evidence elucidated the characteristics of MAIT cells and emphasized the potential roles of MAIT cells in oral lichen planus (OLP), chronic graft-versus-host disease (cGVHD), oral squamous cell carcinoma (OSCC), apical periodontitis (AP) and primary Sjogren's syndrome (pSS).

The Tipped Balance of ILC1/ILC2 in Peripheral Blood of Oral Lichen Planus Is Related to Inflammatory Cytokines

Oral lichen planus (OLP) is an immune-inflammatory disease mediated by T cells. Innate lymphoid cells (ILCs) constitute a novel family of immune cells that initially originate from common innate lymphoid progenitors. Termed “T cells counterparts,” ILCs play a prominent role in inflammatory-immune diseases. However, the characterization of ILCs and their related induced factors were unclear in OLP. In the present study, the phenotypic characteristics of ILCs and their correlation with inflammatory cytokines were explored in the peripheral blood of OLP patients and healthy controls. We found that the proportion of total ILCs was expanded in OLP and was positively correlated with disease severity. The highly skewed distribution of ILC subpopulations was notable in OLP. Specifically, the frequency of ILC1s was significantly increased, while that of ILC2s was significantly reduced in total ILCs of OLP, resulting in the markedly elevated ILC1/ILC2 ratio in OLP. Correspondingly, ILCs in OLP displayed high expression of T-bet but low expression of GATA3. In addition, the IFN-γ expression level was elevated in ILC1s, whereas the IL-4 expression level was decreased in ILC2s. Moreover, ILC-associated activators IL-12, IL-18, and IL-1β were upregulated in OLP plasma, with IL-12 and IL-1β both positively correlated with the ILC1/ILC2 ratio. Further in vitro stimulation tests indicated that OLP plasma remarkedly increased the ILC1/ILC2 ratio, especially that IL-12 and IL-1β tipped the balance between ILC1s and ILC2s toward ILC1s in total ILCs. Overall, elevated levels of IL-12 and IL-1β might act as environmental cues in tipping the balance of ILC1/ILC2 in the peripheral blood of OLP, contributing to the immune dysregulation in OLP.

Immune mechanisms in oral lichen planus

Oral lichen planus (OLP) is a T-cell-mediated inflammatory disease of the oral mucosa that has been extensively researched over many years but as yet the mechanisms of pathogenesis are still not fully understood. Whilst the specific etiologic factors driving OLP remain ambiguous, evidence points to the development of a chronic, dysregulated immune response to OLP-mediating antigens presented by innate immune cells and oral keratinocytes leading to increased cytokine, chemokine and adhesion molecule expression. These molecules recruit T-cells and mast cells to the diseased site and orchestrate a complex interplay between cells that culminates in keratinocyte cell death, mucosal basement membrane destruction and long-term chronicity of the disease. The main lymphocytes involved are thought to be CD8+ cytotoxic and CD4+ Th1 polarised T-cells although recent evidence indicates the involvement of other Th subsets such as Th9, Th17 and Tregs, suggesting that a more complex immune cell relationship exists during the disease process. This review provides an overview of the immune mechanisms at play in OLP pathogenesis with particular emphasis on the role of the different Th subsets and how these recent discoveries may guide research toward identifying potential therapeutic targets.

2-Deoxy-D-glucose impedes T cell-induced apoptosis of keratinocytes in oral lichen planus

Oral lichen planus (OLP) is a T cell–mediated immunoinflammatory disease. Glycolysis plays an essential role in T‐cell immune responses. Blocking glycolytic pathway in activated T cells represents a therapeutic strategy for restraint of immunologic process in autoimmune disorders. 2‐Deoxy‐D‐glucose (2‐DG) has been widely used to probe into glycolysis in immune cells. This study was aimed to explore the role of glycolysis inhibition by 2‐DG on regulating immune responses of OLP‐derived T cells. We observed that lactic dehydrogenase A (LDHA) expression was elevated in OLP lesions and local T cells. 2‐DG inhibited the expression of LDHA, p‐mTOR, Hif1α and PLD2 in T cells; meanwhile, it decreased proliferation and increased apoptosis of T cells. T cells treated by 2‐DG showed lower LDHA expression and elevated apoptosis, resulting in a reduced apoptotic population of keratinocytes that were co‐cultured with them, which was related to the decreased levels of IFN‐γ in co‐culture system. Rapamycin enhanced the effects of 2‐DG on immune responses between T cells and keratinocytes. Thus, these findings indicated that OLP‐derived T cells might be highly dependent upon high glycolysis for proliferation, and 2‐DG treatment combined with rapamycin might be an option to alleviate T‐cell responses, contributing to reducing apoptosis of keratinocytes.

Serum Vitamin Profile in Oral Lichen Planus Patients in Southwest of Iran

Introduction

Oral lichen planus (OLP) is a chronic mucocutaneous disease. It is mainly an immune system-related disorder. Vitamins can modulate immune system functions, and thus, vitamin deficiency might have roles in exacerbating OLP. We aim to determine the serum levels of vitamins A, B12, C, D3, and E in OLP patients.

Methods and Materials

34 OLP patients referred to Shiraz Dental School entered the study. Blood samples were collected and levels of A, B12, C, D3, and E vitamins were measured in serum. 43 healthy people were also included as the control group. Serum levels of vitamins were measured by HPLC (A, B12, D3, and E) and Kiazist analyzing kit (vitamin C).

Results

Most of the patients were female (62.3%), and the mean age of patients was 48.03 ± 11.57. Serum levels of vitamins A, C, and E were lower in OLP patients in comparison with the healthy group; however, the difference was not significant. Vitamins B12 and D3 were higher in the OLP group but the difference was not significant.

Conclusion

Serum levels of vitamins A, B12, C, D3, and E do not have a significant difference in OLP patients and healthy groups. These vitamins may not have a considerable role in OLP pathogenesis in the southwest of Iran.

Interferon-γ activated T-cell IRGM-autophagy axis in oral lichen planus

Oral lichen planus (OLP) is an inflammatory immune disease featured by dense T-cell infiltrate and basal keratinocytes degeneration. Immunity related GTPase M (IRGM) is vital for the induction of autophagy. Our previous studies have demonstrated aberrant autophagy in OLP, however, the involvement of IRGM-autophagy axis in OLP has not yet been revealed. The expression of IRGM and autophagy activity were evaluated in oral mucosal tissues and peripheral T cells of OLP patients and healthy controls, respectively. We found significant upregulation of IRGM and LC3B in lesions of patients with OLP as compared with healthy donors. IRGM, LC3B and NOD2 levels were also elevated in the peripheral T cells of OLP. Then, knockdown of IRGM after electrotransfection with siRNA resulted in attenuated autophagy, growth inhibition, and apoptosis of T cells. In addition, preincubation with IFN-γ promoted the expression of IRGM mRNA and induced autophagy in T cells. Furthermore, IFN-γ decreased the proliferation and apoptosis of T cells, whereas facilitated the viability of keratinocytes in a co-culture system of activated T cells and keratinocytes. Taken together, activated IRGM-autophagy axis under IFN-γ regulation in T cells might participate in the immunoregulatory mechanism of OLP.

Omega-3 polyunsaturated fatty acids: a promising approach for the management of oral lichen planus

BACKGROUND

Oral lichen planus (OLP) is a T-cell-mediated inflammatory disease with a risk of malignant transformation. Although the etiology of OLP is still uncertain, growing evidence suggests that oral microbiota, antigen-specific, and non-specific mechanisms are involved in the pathogenesis of OLP. Antigen-specific mechanisms include antigen presentation, T-cell activation, nuclear factor-kappa B signaling pathway, and cytokine secretion, while non-specific mechanisms consist of matrix metalloproteinases (MMP)-9 upregulation, psychological pressure, oxidative damage, aberrant expression of microRNAs (miRNAs), and autophagy. Till now, there is no cure for OLP, and the main purpose of OLP therapy is symptomatic control.

FINDING

Seafood and its derivative omega-3 polyunsaturated fatty acids (n-3 PUFAs) can suppress antigen presentation, T-cell activation, and nuclear factor-kappa B signaling pathway, modulate the overexpressed inflammatory cytokines, inhibit the expression of MMP-9, as well as regulate the expression of miRNAs and autophagy. And they are possible agents for ameliorating psychological disorder and oxidative damage. Moreover, n-3 PUFAs supplementation has a beneficial effect on preventing tumorigenesis.

CONCLUSION

n-3 PUFAs consumption may provide a non-toxic, inexpensive administration for OLP.

HIF1α/PLD2 axis linked to glycolysis induces T-cell immunity in oral lichen planus

BACKGROUND

Oral lichen planus (OLP) is a common T-cell-mediated immunological disease. Hypoxia-inducible factor 1 alpha (HIF1α) plays an integral role in the glycolytic metabolism that facilitates immune functions from boosting cellular proliferative capacity to driving T-cell differentiation. In general, phospholipase D2 (PLD2) is required for HIF1α regulation. However, the involvement of HIF1α and PLD2 in dysfunctional T-cell immunity of OLP remains elusive.

METHODS

HIF1α and PLD2 expression in OLP lesions were determined by qRT-PCR, immunohistochemistry and immunofluorescence staining, and correlation analysis was carried out between their expressions. HIF1α or PLD2 silencing in T cells was performed to investigate the glycolytic alteration. Then their involvement in T-cell immunobiology was evaluated by detecting cell proliferation, cell cycle, apoptosis, and effector subsets differentiation. Additionally, the modulation of HIF1α on PLD2 expression and the engagement of mTOR in this process were explored.

RESULTS

HIF1α and PLD2 protein were highly expressed in OLP lesions and they were both observed in large numbers of local CD3⁺ T cells in OLP. Besides, HIF1α expression was positively correlated with PLD2 expression in OLP. Both HIF1α and PLD2 promoted T-cell proliferation and pro-inflammatory phenotype differentiation, which was associated with the upregulation of glycolysis mediated by HIF1α or PLD2. Moreover, HIF1α induced PLD2 expression in an mTOR-independent way.

CONCLUSIONS

HIF1α/PLD2 axis was supposed to be critical regulatory signaling involved in the T-cell immunity of OLP.

The mTOR-glycolytic pathway promotes T-cell immunobiology in oral lichen planus

Oral lichen planus (OLP) is a T-cell-mediated inflammatory mucosal disease. T cells require rapid metabolic reprogramming for their effector functions after activation by immunologic stimuli. The mammalian target of rapamycin (mTOR) is a central player in the metabolic reprogramming and immune responses of T cells. The present study investigated the role of mTOR in the immunometabolism of OLP. mTOR and its direct target eukaryotic initiation factor 4E binding protein 1 (4E-BP1) were highly phosphorylated in peripheral T cells of OLP patients. Rapamycin-mediated blockage of mTOR activation restrained both T-cell proliferation and DNA synthesis, promoted apoptosis, and decreased Th1/Th2 and Th17/Treg ratios. Dual blockage of mTOR and phosphatidylinositol 3-kinase (PI3K) exerted stronger inhibition on T-cell immunobiology than selective repression of PI3K alone. Rapamycin also blocked the glycolytic pathway in T cells. Moreover, glucose-induced activation of mTOR-glycolytic pathway increased T-cell proliferation, DNA synthesis, and the Th17/Treg ratio, and decreased T-cell apoptosis. In contrast, inhibition of glycolysis by 2-Deoxy-d-glucose (2-DG) yielded the opposite effects on T-cell immunobiology by blocking the mTOR pathway. In conclusion, enhanced activation of the mTOR-glycolytic pathway promoted T-cell immunobiology, suggesting that dysregulation of immunometabolism might be associated with T-cell dysfunction in OLP.

Insulin-like growth factor 1 exhibits the pro-autophagic and anti-apoptotic activity on T cells of oral lichen planus

BACKGROUND

Oral lichen planus (OLP) is an autoimmune mucocutaneous disease characterized by T cell infiltrating in microenvironment. T cell-mediated immune dysfunctions are of importance in the pathogenesis of OLP. Insulin-like growth factor 1 (IGF1) has profound effects on maintenance of immune functions; however, its specific mechanism in OLP remains unknown. This study aims to explore how IGF1 regulates T-cell immune functions in OLP.

METHODS

IGF1 in OLP lesions was stained by immunohistochemistry and immunofluorescence. Additionally, proliferation, apoptosis and autophagy of T cells were examined after stimulation with IGF1 for 24 h, respectively. Z-VAD-FMK, a pan-caspase inhibitor, was used to explore IGF1-mediated crosstalk between apoptosis and autophagy. The modulation of IGF1 on ERK and PI3K/mTOR pathway was also analyzed.

RESULTS

IGF1 was increased in OLP lesions and was remarkably co-located with T cells. IGF1 significantly enhanced T-cell proliferation, suppressed apoptosis and induced autophagic flux. Moreover, autophagy was induced by apoptosis inhibitor, Z-VAD-FMK, thereby reducing death of T cells. IGF1 could facilitate Z-VAD-FMK-induced autophagy and then decrease proportion of apoptotic T cells. IGF1-treated T cells also showed elevated phosphorylation of ERK, PI3K and mTOR.

CONCLUSIONS

IGF1 inhibited apoptosis and promoted autophagy in T cells, potentially contributing to the pathogenesis of OLP.

Black pepper and its bioactive constituent piperine: promising therapeutic strategies for oral lichen planus

Oral lichen planus (OLP) is a common T cell-mediated chronic inflammatory disease with malignant potential and unclear etiology. The present study suggests that antigen-specific mechanisms in which dentritic cells, T lymphocytes and NF-κB signaling pathway play critical roles, are involved in the pathogenesis of OLP. Additionally, it has been indicated that altered expression of cyclooxygenase 2 (COX-2) and imbalanced oxidant-antioxidant status as well as psychological issue may act as promoters to the development of OLP. Therapies for OLP are primarily aimed to control symptoms and a specific cure is not yet available. Black pepper and its principle bioactive compound piperine have been reported to possess remarkable pharmacological activities. Not only has piperine been evidenced to exhibit repressive effects on the maturation of dentritic cells, the proliferation, activation and function of T lymphocytes as well as the NF-κB signaling pathway, but also to suppress the overproduction of COX-2 and weaken the oxidative stress. Furthermore, piperine might be a possible agent for alleviating psychological disorders and preventing carcinogenesis. Given all these into consideration, piperine may be a novel and effective therapeutic strategy for OLP.

Mixed and inhomogeneous expression profile of Th1/Th2 related cytokines detected by cytometric bead array in the saliva of patients with oral lichen planus

OBJECTIVE

The aim of this study was to measure T helper (Th) 1/Th2-related cytokine expression in saliva from patients with oral lichen planus (OLP), compared with healthy controls (HC group) and controls with recurrent aphthous ulcers (RAU group).

STUDY DESIGN

Saliva was collected from 41 patients with OLP, 14 HCs, and 14 controls with RAU for Th1/Th2-related cytokines analysis with cytometric bead array. Disease activity in OLP was recorded by reticulation/keratosis, erythema, and ulceration scores.

RESULTS

Interleukin (IL)-6, IL-10, interferon-γ (IFN-γ), and IFN-γ/IL-4 in saliva were significantly higher in the OLP group than in the HC group. A positive and significant correlation among IL-6, IL-10, and reticulation/keratosis, erythema, and ulceration scores in the OLP group was revealed. Significantly increased IL-4, IL-5, IL-6, IL-10, tumor necrosis factor-α and IFN-γ/IL-4 were found in the RAU group.

CONCLUSIONS

Salivary cytokine profiles analyzed by cytometric bead array may provide a convenient research approach to OLP. Data indicated complicated Th1/Th2-related cytokine profile changes, rather than simple dominance model, in OLP. IL-10 and especially IL-6 may provide a surrogate endpoint for monitoring OLP.

Experimental study on 1,25(OH)2 D3 amelioration of oral lichen planus through regulating NF-κB signaling pathway

OBJECTIVE

To explore the protective function of vitamin D (VD)/vitamin D receptor (VDR) on the development of oral lichen planus (OLP) and elaborate the underling mechanism of it.

METHODS

H&E staining, myeloid peroxidase (MPO) assays, quantitative PCR (qPCR), Western blotting, and Elisa were used to test the human biopsies and serum. QPCR, Western blotting, Elisa, and siRNA transfection were also performed in LPS-induced keratinocytes to observe the functions of vitamin D and VDR.

RESULTS

The lack of VDR in the diseased biopsies from OLP patients was associated with activated helper T-cell type 1 (Th1)-driven inflammatory response. Importantly, the status of serum 25-hydroxyvitamin D of OLP patients was reduced consistently. In a cultured cell model, 1,25(OH)₂ D₃ could downregulate excessive production of pro-inflammatory factors induced by lipopolysaccharide (LPS) in keratinocyte HaCat cells. Mechanistically, even though LPS-induced cytokines in keratinocytes were inhibited both by nuclear factor-κB (NF-κB) inhibitor and by activator protein 1 (AP-1) inhibitor, VDR-dependent 1,25(OH)₂ D₃ blocked the activation of phosphorylated-NF-κB p65 rather than c-Jun/c-Fos in the presence of LPS stimulation.

CONCLUSION

These results suggest that 1,25(OH)₂ D₃ plays an anti-inflammatory role in OLP by mediating NF-κB signaling pathway but not AP-1 signaling pathway with a VDR-dependent manner, predicting vitamin D supplement may be a potential strategy for the OLP management.

Intracellular Ca2+ and related proteins in patients with oral lichen planus

Oral lichen planus (OLP) is suggested to be a T cell-mediated chronic inflammatory oral mucosal disease. Gene expressed in the oligodendrocyte lineage-myelin basic proteins (Golli-MBP) and stromal interaction molecule 1 (STIM1) are important in the activation and function of T lymphocytes. This study aimed to analyze and compare the expression of Golli-MBP and STIM1 between OLP patients and healthy controls and to analyze the level of intracellular Ca(2+), which is involved in lymphocyte activation. The Ca(2+) fluorescent probe, Fluo-3/AM, was used to test the level of intracellular Ca(2+) in patients with OLP and healthy controls peripheral blood lymphocytes. Golli-MBP and STIM1 mRNA and protein levels were analyzed using quantitative real-time PCR and Western blot, respectively. Following lymphocyte activation, the intracellular Ca(2+) in OLP patients was markedly lower than that in the control group (P < 0.001). In OLP patients, the expression of Golli-MBP mRNA and protein was significantly upregulated compared to those of the control group (P < 0.001). Similarly, OLP patients showed markedly upregulated levels of STIM1 mRNA expression (P < 0.01) and protein compared to healthy controls. The intracellular Ca(2+) of OLP patients was markedly lower than that of healthy controls. This evidence may indicate that Ca(2+) signaling pathways in OLP patients are abnormal. The overexpression of Golli-MBP and STIM1 may play a role in the pathogenesis of OLP.

Immunoexpression of Th17-related cytokines in oral lichen planus

A recently described lineage of lymphocytes, Th17 cells, has been associated with inflammatory and autoimmune diseases. The aim of this article was to assess the immunoexpression of cytokines related to this lineage, interleukin-17 (IL-17) and IL-23 and in reticular and erosive oral lichen planus (OLP). The sample included 41 cases of OLP (23 reticular and 18 erosive) and 10 cases of inflammatory fibrous hyperplasia (IFH). Lymphocytes exhibiting cytoplasmic immunostaining were counted. Epithelial immunostaining was also evaluated. There was no statistical differences in the number of IL-17 and IL-23 lymphocytes between the OLP (55.40 and 48.40, respectively) and IFH (39.30 and 44.40, respectively). A significantly higher number of IL-23 lymphocytes was found in erosive OLP group (63.80) when compared with reticular (41.40) and IFH lesions (44.40) (P=0.019). Furthermore, epithelial immunopositivity for IL-17 and IL-23 was higher in OLP lesions than in IFH (P=0.012 and P=0.011, respectively). A significantly higher number of IL-23 lymphocytes in erosive OLP and the strong epithelial immunopositivity for IL-23 and IL-17 in OLP group could suggest an important participation of TCD4 Th17 response in this disorder.

Etiology and pathogenesis of oral lichen planus: an overview

Oral lichen planus is a noninfectious, chronic inflammatory condition that involves the oral mucosal stratified squamous epithelium and the underlying lamina propria and may be accompanied by skin lesions. This overview describes the current understanding of the immunopathologic mechanisms implicated in oral lichen planus.

Altered Autophagy-Associated Genes Expression in T Cells of Oral Lichen Planus Correlated with Clinical Features

Oral lichen planus (OLP) is a T cell-mediated inflammatory autoimmune disease. Autophagy has emerged as a fundamental trafficking event in mediating T cell response, which plays crucial roles in innate and adaptive immunity. The present study mainly investigated the mRNA expression of autophagy-associated genes in peripheral blood T cells of OLP patients and evaluated correlations between their expression and the clinical features of OLP. Five differentially expressed autophagy-associated genes were identified by autophagy array. Quantitative real-time RT-PCR results confirmed that IGF1 expression in the peripheral blood T cells of OLP patients was significantly higher than that in controls, especially in female and middle-aged (30-50 years old) OLP patients. In addition, ATG9B mRNA levels were significantly lower in nonerosive OLP patients. However, no significant differences were found in the expression of HGS, ESR1, and SNCA between OLP patients and controls. Taken together, dysregulation of T cell autophagy may be involved in immune response of OLP and may be correlated with clinical patterns.

MicroRNA-155-IFN-γ Feedback Loop in CD4(+)T Cells of Erosive type Oral Lichen Planus

Oral lichen planus (OLP) is a T cell-mediated immune disorder, and we have indicated a Th1-dominated immune response in OLP. MicroRNA-155 (miR-155) could promote Th1 cells polarization. The present study aims to determine the role of miR-155 in immune response of OLP. The expression of miR-155 and the target mRNA was tested by Real-Time PCR. The serum levels of IL-2, 4, 10 and IFN-γ were examined with ELISA. Furthermore, in vitro study was built to observe the function of miR-155 in erosive-type OLP (EOLP). Finally, we determined the expression and correlation of miR-155 and SOCS1 in EOLP CD4⁺ T cells. The results showed miR-155 was high related with the disease severities. Besides, serum IFN-γ was specifically increased in EOLP group, while IL-4 was decreased. In vitro studies showed miR-155 could reinforce IFN-γ signal transducer, and the induction of IFN-γ could also promote miR-155 expression in EOLP CD4⁺ T cells. In addition, miR-155 levels were negatively related with SOCS1 mRNA expression in EOLP CD4⁺ T cells. Our study revealed a positive miR-155- IFN-γ feedback loop in EOLP CD4⁺ T cell, which might contribute to the Th1-dominated immune response. Furthermore, miR-155 could be used for the evaluation and treatment of OLP.

Foxp3 gene expression in oral lichen planus: a clinicopathological study

CD4+CD25+ Forkhead‑box protein 3 (Foxp3+) regulatory T cells are important in oral lichen planus (OLP). The present study aimed to investigate Foxp3 expression in CD4+CD25+ T cells of peripheral blood mononuclear cells and oral lesions in patients diagnosed with OLP, who were grouped as OLP subtype, duration and relapse. Using quantitative polymerase chain reaction (qPCR), western blotting and immunohistochemistry, Foxp3 expression levels in explants of oral lesions and CD4+CD25+ T cells from 32 patients with OLP were measured and compared, with 10 healthy subjects as the control group. Foxp3 mRNA expression levels in the explants of oral lesions and circulating CD4+CD25+ T cells in patients with OLP were significantly higher than those in the control group (P<0.05). In patients with clinically erosive lesions, Foxp3 mRNA expression was significantly lower in circulating CD4+CD25+ T cells and tissue explants compared to patients with reticular lesions (P<0.01 and P<0.05, respectively), and lowest in patients with a history of OLP of >1 year or with a history of relapse (P<0.05 and P<0.01, respectively). Foxp3 protein levels in reticular OLP were significantly higher than those in erosive OLP and the control group. The incidence of Foxp3 protein expression in OLP tissues was 36.24±18.92 and 10.44±6.51% in normal oral mucosa (P=0.019). Atrophic/erosive OLP lesions showed a higher proportion of Foxp3‑expressing cells than that of reticular OLP lesions (P<0.05). This study indicated that Foxp3 expression in patients with OLP is associated with the severity and duration of the disorder, suggesting altered immune suppression in the development, clinical course and responsiveness to treatment.

Hydroxychloroquine decreases the upregulated frequencies of Tregs in patients with oral lichen planus

OBJECTIVE

Regulatory T cells (Tregs) have emerged as important mediators in inflammatory and autoimmune diseases. We investigated the possible involvement of Tregs in oral lichen planus (OLP) and the influence of clinical therapy (hydroxychloroquine and prednisone) on the frequencies of Tregs in OLP patients.

MATERIALS AND METHODS

One hundred fifty patients diagnosed with OLP were the study cohort. Levels of Tregs in blood and tissues were detected using flow cytometry and immunostaining, respectively. Cytokine production was assessed using a proteome profiler array and determined by enzyme-linked immunosorbent assay. mRNA expression of transcription factors was detected by real-time quantitative PCR. Hydroxychloroquine or prednisone was used to treat patients randomly. The frequency of Tregs was detected before treatment and 2 weeks after treatment.

RESULTS

Compared with healthy volunteers, OLP patients had a higher proportion of Tregs in serum and tissues before treatment (P < 0.001). Serum concentrations of interleukin (IL)-8, transforming growth factor (TGF)-β1, and IL-10 were significantly higher in patients than those in healthy controls. mRNA expression of Treg-related genes, including TGF-β, IL-10, signal transducer and activator of transcription 6, and GATA binding protein 3, were upregulated significantly in OLP patients. The frequency of Tregs was downregulated after hydroxychloroquine treatment.

CONCLUSIONS

These results suggest that Tregs may contribute to the immunopathogenesis of OLP and may provide a new therapeutic target for OLP treatment.

CLINICAL RELEVANCE

T cell-mediated immune dysfunction may have a crucial role in OLP development. However, T helper 1 (Th1)/Th2 imbalance does not appear to be sufficient to understand the pathogenesis of OLP. This is the first study to show that Tregs are involved in the immunopathogenesis of OLP.

Interferon-γ and interleukin-4 detected in serum and saliva from patients with oral lichen planus

Our previous salivary study had demonstrated an apparent T helper 2 (Th2)-predominance in saliva of oral lichen planus (OLP) patients and suggested a potential of salivary interleukin-4 (IL-4) as a biomarker for monitoring disease severity. To further determine the consistency of Th1/Th2 bias of OLP, this study investigated the expression profile of interferon-γ (IFN-γ) and IL-4 in serum and the relationship of the serum levels of these cytokines with their saliva partners. Sixty ethnic Chinese patients with OLP (40 of the erythematous/ulcerative form and 20 of the reticular form) were recruited for this study, with 40 age–sex-matched healthy volunteers as control group. IFN-γ and IL-4 levels in serum and paired saliva samples were screened by enzyme-linked immunosorbent assay. OLP patient showed a low-level IFN-γ but high-level IL-4 expression profile in both serum and saliva, with a lower IFN-γ/IL-4 ratio. Serum IL-4 level in the erythematous/ulcerative group was significantly higher than that in the reticular group. Serum levels of IFN-γ and IL-4 were significantly and positively correlated with their saliva partners. These results provided more evidence for Th2 cytokine-predominant immune imbalance in OLP, as well as the potential of IL-4 as the biomarker for monitoring severity of OLP.

Increasing CCL5/CCR5 on CD4+ T cells in peripheral blood of oral lichen planus

Oral lichen planus (OLP) is a T cell-mediated autoimmune disease of oral mucosa, in which T helper 1 (Th1) cells are greatly involved. Chemokine CCL5 is required for T cells infiltration and activation. CCR5, one of its receptors, specifically expressed on Th1 cells among CD4(+) T cells, can be up-regulated by Th1 cytokines like interleukin2 (IL-2) and interferon-gamma (IFN-γ), and down-regulated by Th2 cytokines like IL-4. The present study aimed to determine whether CCL5 and CCR5 had effects on the immune response of OLP. We analyzed the proportion of CCR5(+)CD4(+) T cells in CD4(+) T cells using flow cytometry and the serum levels of CCL5, IL-2, IFN-γ, and IL-4 with ELISA. MicroRNA-125a (miR-125a), a blocker of CCL5, was examined with RT-PCR. The results showed both the serum CCL5 and the percentage of CCR5(+)CD4(+) T cells elevated in OLP patients. Serum IL-2 and IFN-γ increased in OLP patients, but IL-4 decreased. MiR-125a was down-regulated in OLP patients, and there was a negative correlation between miR-125a content and the OLP severity which was measured with a RAE (reticular, atrophic and erosive lesion) scoring system. In conclusion, increasing CCl5/CCR5 might participate in the immune response of OLP. Th1-type cytokines environment presented in OLP probably performed as a magnifier for the CCR5. Moreover, miR-125a might be a candidate biomarker to estimate the severity of OLP.

Proliferation and apoptosis of peripheral blood mononuclear cells in patients with oral lichen planus

Oral lichen planus (OLP) is generally accepted to be a T cell-mediated chronic inflammatory disease with an unclear pathogenesis. There have been numerous studies on the proliferation and apoptosis of T cells in situ. In contrast, research on the proliferation and apoptosis of peripheral blood mononuclear cells (PBMCs) in patients with OLP is rare. The aim of the present study was to investigate the proliferation and apoptosis of PBMCs in patients with OLP. PBMCs were isolated from 20 patients with reticular OLP, 20 patients with atrophic-erosive OLP, and 20 healthy volunteers. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl-2,5-tetrazolium bromide assays were performed to investigate the proliferation of PBMCs, and caspase-3 colorimetric assays were performed to investigate the apoptosis of PBMCs. The proliferation rate of PBMCs in atrophic-erosive OLP subjects was significantly higher than that in both healthy (P < 0.05) and reticular OLP (P < 0.05) subjects. In contrast, the proliferation rate of PBMCs in reticular OLP subjects was significantly lower than that in healthy subjects (P < 0.05). The apoptosis rates of PBMCs in OLP subjects (P < 0.05) and atrophic-erosive OLP subjects (P < 0.05) were significantly lower than the apoptosis rate in the healthy group. Our findings reinforce the view that T cell-mediated immune responses play a critical role in the pathogenesis of OLP. It can reasonably be concluded that these abnormalities are linked to the presence of inflammatory infiltrates.