Immunopathogenesis of oral lichen planus

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.

A comparison of proliferative capacity of reticular and erosive variants of oral lichen planus by argyrophilic nucleolar organizer regions method

Background

Oral lichen planus (OLP), an immune mediated disorder, has been recognized since 1869 and is presented as any one of the six variants. Reticular and erosive are the most frequently encountered. Its proliferative capacity can give some information regarding its progression. We adopted the argyrophilic nucleolar organizer regions (AgNORs) method because of its simplicity to use and dependable results. We evaluated AgNORs in basal, suprabasal, and squamous cell layers. We also compared these three layers within two variants, reticular, and erosive.

Materials and Methods

Thirty clinically diagnosed patients of OLP were included in the study. Reticular and erosive variants were included in our study. This was followed by hematoxylin and eosin staining and later by the AgNOR method. The mean number of AgNORs per nucleus was calculated.

Results

Thirteen males and 17 females were the gender distribution. Twenty-three (76.67%) had reticular pattern and seven (23.33%) had erosive pattern. The basal cell layer had the highest mean AgNOR compared to suprabasal and squamous layers. Even among, erosive and reticular variants, the former had higher mean AgNOR counts.

Discussion

Our results suggest that the inflammatory infiltrate close to the epithelial cells can alter the proliferation index for the pattern of protein synthesis of these cells. Moreover, the high proliferative index in OLP can be related to a specific immunologic response.

Conclusion

We conclude that AgNOR can be used as a proliferative marker in earlier lesions to detect the severity.

Histopathologic evaluation of oral lichen planus and oral lichenoid reaction: A comparative analysis based on basement membrane thickness and the distribution of mast cells

Background:

Lichen planus is a chronic mucocutaneous disease of unknown etiology with well-established clinical and microscopic features. Oral lichenoid reactions are a family of lesions triggered by contact with specific agents such as metallic restorative materials, resins and drugs. Oral lichenoid reactions share clinical and histological features of oral lichen planus (OLP) but has varied management options. Hence, the discrimination between these two lesions is a major challenge for clinicians as well as pathologists.

Aim:

Histopathologic categorization of OLP and oral lichenoid reaction by comparing the thickness of basement membrane and the distribution of mast cells using special stains.

Materials and Methods:

The test group consists of formalin-fixed paraffin-embedded blocks of OLP (n = 15), and oral lichenoid reactions (n = 15) obtained from the archives of the Department of Oral Pathology, Amrita School of Dentistry. Three serial sections of 4 μm thickness were cut from each block. The sections were stained with H & E, periodic acid-Schiff (PAS) and toluidine blue, respectively.

Results:

A significant increase in the maximum basement membrane thickness (BMT) was noticed in OLP when compared to oral lichenoid reaction. A definite increase was also noticed in the number of mast cells in OLP and oral lichenoid reaction when compared to normal oral mucosa. There was a statistically significant increase in the number of degranulated mast cells in the deeper connective tissue in oral lichenoid reaction when compared to OLP.

Conclusion:

OLP and oral lichenoid reactions are two different entities showing similar clinical and microscopic presentation. The histochemical analysis of basement membrane and mast cells in these lesions might provide a more authentic method for differentiating these two lesions and might be of utmost value in deciding the treatment options.

Study of Langerhans cells and T lymphocytes in vulvar lichen sclerosus lesions

BACKGROUND

The aetiology and pathogenesis of vulvar lichen sclerosus (LS), a chronic inflammatory disease, is not completely clear. It has been found that local cellular immune abnormalities play an important role in the immune mechanism of LS, mainly characterised by abnormal numbers of Langerhans cells in the epidermis and abnormal numbers of dermal T lymphocytes.

OBJECTIVE

To evaluate the densities of Langerhans cells and T-lymphocyte subpopulations in vulvar LS.

METHODS

The density of Langerhans cells in the epidermis, and CD3⁺ , CD4⁺ and CD8⁺ T cells in the dermis of seven early-stage and eight late-stage cases of vulvar LS were detected with direct immunofluorescence, and compared with 15 normal controls.

RESULTS

The density of Langerhans cells in the late-stage group was significantly higher than in the normal group (P = 0.001). The densities of CD3⁺ , CD4⁺ and CD8⁺ T lymphocytes in both the early- and late-stage (deeper dermis) groups were higher than in the normal group (P < 0.05). The ratio of CD4⁺ /CD8⁺ T lymphocytes in the early-stage and normal groups showed no significant difference (P = 0.151), while the late-stage (deeper dermis) groups decreased significantly compared with early-stage, late-stage (upper dermis) and normal groups (P < 0.001).

CONCLUSION

The densities of Langerhans cells, CD3⁺ , CD4⁺ and CD8⁺ T cells, and the ratio of CD4⁺ /CD8⁺ T lymphocytes were different in different stages of LS, which supports the important role of cellular immunity in mechanisms of LS.

New Viral Facets in Oral Diseases: The EBV Paradox

The oral cavity contributes to overall health, psychosocial well-being and quality of human life. Oral inflammatory diseases represent a major global health problem with significant social and economic impact. The development of effective therapies, therefore, requires deeper insights into the etiopathogenesis of oral diseases. Epstein–Barr virus (EBV) infection results in a life-long persistence of the virus in the host and has been associated with numerous oral inflammatory diseases including oral lichen planus (OLP), periodontal disease and Sjogren’s syndrome (SS). There is considerable evidence that the EBV infection is a strong risk factor for the development and progression of these conditions, but is EBV a true pathogen? This long-standing EBV paradox yet needs to be solved. This review discusses novel viral aspects of the etiopathogenesis of non-tumorigenic diseases in the oral cavity, in particular, the contribution of EBV in OLP, periodontitis and SS, the tropism of EBV infection, the major players involved in the etiopathogenic mechanisms and emerging contribution of EBV-pathogenic bacteria bidirectional interaction. It also proposes the involvement of EBV-infected plasma cells in the development and progression of oral inflammatory diseases. A new direction for preventing and treating these conditions may focus on controlling pathogenic EBV with anti-herpetic drugs.

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.

Severity of oral lichen planus and oral lichenoid lesions is associated with anxiety

OBJECTIVES

Oral lichen planus (OLP) and oral lichenoid lesions (OLL) are chronic inflammatory diseases whose symptoms can impair patient's quality of life (QoL). Psychological factors seem to play an important role in these diseases. This study aimed to determine the impact of oral health and anxiety levels on the QoL of patients with OLP and OLL.

PATIENTS AND METHODS

This was a cross-sectional study composed of OLP and OLL patients and a control group matched by age and sex with no autoimmune/inflammatory or malignant oral lesions. Anxiety levels and oral health impact on QoL were assessed using the Hamilton Anxiety Scale (HAM-A) and the Oral Health Impact Profile-14 (OHIP-14), respectively. The instruments were filled through personal interview before starting the treatment for oral lesions.

RESULTS

A total of 87 patients diagnosed with OLP (n = 45) and OLL (n = 42), and 87 controls were included in the study. Statistical differences were observed for the psychic and somatic anxiety dimensions between severities of diseases. Patients with OLP or OLL had higher scores for the OHIP-14 dimensions physiological discomfort and social limitation compared with controls. In addition, higher scores for physical pain, physical disability, social disability, and handicap were detected among patients with greater severity.

CONCLUSION

Greater severity of OLP and OLL seems to be associated with increased levels of anxiety, higher scores of oral health impact profile, and decreased QoL.

CLINICAL RELEVANCE

Patients with severe OLP/OLL may benefit from additional therapeutic treatments, such as psychological and/or psychiatric management, concomitant to treatment specific to oral lesions.

Aberrant histone modification and inflammatory cytokine production of peripheral CD4+ T cells in patients with oral lichen planus

Backgrounds

To investigate alterations in histone modification and histone deacetylases (HDACs) in patients with oral lichen planus (OLP), and to evaluate correlations with inflammatory cytokine production.

Methods

Global histone H3/H4 acetylation and HDAC activity in CD4+ T cells from 23 patients with OLP and 10 healthy control subjects were examined using spectrophotometry. The mRNA levels of eight members of four classes of HDAC genes were measured by real‐time quantitative polymerase chain reaction. Forty cytokines involved in inflammation were examined with a cytokine array. The correlation between histone modification and cytokine production was analyzed.

Results

Global histone H3 hypo‐acetylation was observed in OLP patients. Patients with OLP had significantly higher HDACs activity,and higher HDAC6 and HDAC7 mRNA level compared with the controls. Of the 40 cytokines in the cytokine array, eight were significantly increased in OLP patients: interleukin (IL)‐4, IL‐8, IL‐1ra, tumor necrosis factor receptor II (TNFR II), macrophage inflammatory protein 1b (MIP‐1b), fibrosis‐associated tissue inhibitors of metalloproteinase 1 (TIMP)‐1, monocyte chemotactic protein 1 (MCP‐1), and eotaxin‐2. In the OLP group, the acetylation level of histone H3 was negatively correlated with IL‐4 and MCP‐1 production, and the expression of HDAC6 mRNA was positively correlated with MCP‐1 production. In the non‐erosive subgroup, acetylation of histone H3 was negatively correlated with IL‐4, IL‐16, and TIMP‐2 production. In the erosive OLP subgroup, the expression of HDAC7 mRNA was positively correlated with MIP‐1a production.

Conclusion

Aberrant histone modification of CD4+ T cells in peripheral blood could occur in OLP patients, and possibly affects inflammatory cytokine production.

MicroRNA Microarray-Based Identification of Involvement of miR-155 and miR-19a in Development of Oral Lichen Planus (OLP) by Modulating Th1/Th2 Balance via Targeting eNOS and Toll-Like Receptor 2 (TLR2)

Background

A wide range of microRNAs (miRNAs) have been shown to play a significant role in disease regulation. The objective of this study was to explore the role of miR-155 and miR-19a in the regulation of oral lichen planus (OLP).

Material/Methods

Microarray assay, real-time PCR, Western blot assay, computational analysis, luciferase assay, ELISA, and immunohistochemistry analysis were carried out to investigate the role of miR-155 and miR-19a in OLP.

Results

According to microarray assay and real-time PCR results, the expression of miR-155 was most significantly decreased among the 16 candidate miRNAs in the OLP group, whereas the expression of miR-19a was most significantly increased. MiR-155 and miR-19a directly targeted endothelial nitric oxide synthase (eNOS) and TLR2, respectively, since only the cells co-transfected with miR-155/wild-type eNOS 3′UTR or cells co-transfected with miR-19a/wild-type TLR2 3′UTR exhibited decreased luciferase activity. In addition, the expression of TLR2 was highly upregulated in OLP, whereas the expression of eNOS was significantly downregulated. A negative correlation was found between miR-19a and TLR2 mRNA, with a coefficient value of −0.40. Similarly, a negative correlation was found between miR-155 and eNOS mRNA, with a coefficient value of −0.54. A lower level of NO, IL-4, IL-5, and IL-10 was observed in OLP, which was also accompanied by a higher level of TNF-α and IFN-γ. Finally, the upregulation in miR-155 directly decreased the expression of eNOS and further inhibited the production of NO. Downregulation of miR-19a directly increased the expression of TLR2. The inhibition of NO production and the enhancement in TLR2 expression synergistically increased the production of TNF-α and IFN-γ, while decreasing the levels of IL-4, IL-5, and IL-10.

Conclusions

In this study, the peripheral blood mononuclear cells (PBMCs) from subjects with or without OLP were collected and their gene expression profiles were compared. It was found that OLP changed the expression profile of miR-155 and miR-19a, which in turn directly affected the production of eNOS and TLR2, respectively. In addition, by synergistically inducing an imbalance between Th1 and Th2, the simultaneous deregulation of miR-155/eNOS and miR-19a/TLR2 was responsible for an elevated risk of OLP.

The relationship between levels of salivary and serum interleukin-6 and oral lichen planus: A systematic review and meta-analysis

BACKGROUND

The relationship between levels of salivary and serum interleukin (IL)-6 and oral lichen planus (OLP) is not understood fully. The authors conducted a systematic review and meta-analysis to compare levels of salivary and serum IL-6 among people with OLP and healthy control participants.

METHODS

The authors searched the literature for studies whose investigators had evaluated the relationships between IL-6 and OLP before treatment. The authors used meta-analysis to compare the standardized mean differences (SMD) of the levels of salivary and serum IL-6 between people who had OLP and people who did not have OLP and between patients with erosive OLP and patients with nonerosive OLP.

RESULTS

The results of separate meta-analyses, which included 5 studies each, indicated that the levels of salivary and serum IL-6 were significantly higher among patients with OLP than among healthy control participants (SMD, 2.35; 95% confidence interval [CI], 0.50 to 4.19; P = .01; and SMD, 2.03; 95% CI, 0.74 to 3.33; P = .002; respectively). The results of a meta-analysis of 4 studies indicated that the levels of IL-6 were not significantly different between patients with erosive OLP and patients with nonerosive OLP (SMD, 1.37; 95% CI, -0.26 to 3.00; P = .10). There was significant heterogeneity among the studies (P < .00001).

CONCLUSIONS

Through the results of this meta-analysis, the authors found significant differences in the levels of IL-6 in saliva and serum between patients with OLP and healthy control participants. The authors found no differences in the levels of serum IL-6 between patients with erosive OLP and patients with nonerosive OLP. These results should be considered with caution because there was a high degree of heterogeneity among studies.

PRACTICAL IMPLICATIONS

Levels of IL-6 in saliva and serum may be potential biomarkers for OLP. However, additional research is needed to confirm findings of this meta-analysis.

Overexpression and varied clinical significance of Th9 versus Th17 cells in distinct subtypes of oral lichen planus

OBJECTIVE

Oral lichen planus (OLP) presents with large numbers of T lymphocytes accumulating beneath the epithelium of the oral mucosa; however, its aetiology remains obscure. A potential role for an emerging novel T cell subset, Th9, in OLP has recently been suggested but remains to be clarified. The current aim was to investigate the expression and potential clinical significance of Th9 cells in distinct subtypes of OLP.

MATERIALS AND METHODS

Peripheral blood samples were collected from 41 OLP patients and 18 healthy controls (HCs). Flow cytometric analysis was used to detect the CD4+ T helper subset Th9 (IL-9⁺IL-17^-CD4⁺ Th cells) and Th17 (IL-9^-IL-17⁺CD4⁺ Th cells) expression levels.

RESULTS

Flow cytometry results showed significantly elevated levels of Th9 cells in reticular and erosive OLP compared to HCs. Th9 expression in erosive OLP was less than in reticular OLP, indicating that Th9 but not Th17 cells may play a predominant role in reticular disease. However, in erosive OLP patients, we found much higher levels of Th17 cells compared to reticular OLP patients and HCs, indicating that Th17 dominates in erosive OLP. Statistical analysis showed positive correlations of Th9 cells and Th17 cells in patients with reticular or erosive OLP but none in HCs.

CONCLUSIONS

Th9 and Th17 cells may take the predominant roles in reticular and erosive OLP respectively, and their numbers were positively correlated in reticular and erosive OLP patients. Elevated circulating Th9 cells may help maintain immune balance in OLP immunopathogenesis, which requires further investigation.

Antimicrobial agent triclosan is a proton ionophore uncoupler of mitochondria in living rat and human mast cells and in primary human keratinocytes

Triclosan (TCS) is an antimicrobial used widely in hospitals and personal care products, at ~10 mm. Human skin efficiently absorbs TCS. Mast cells are ubiquitous key players both in physiological processes and in disease, including asthma, cancer and autism. We previously showed that non-cytotoxic levels of TCS inhibit degranulation, the release of histamine and other mediators, from rat basophilic leukemia mast cells (RBL-2H3), and in this study, we replicate this finding in human mast cells (HMC-1.2). Our investigation into the molecular mechanisms underlying this effect led to the discovery that TCS disrupts adenosine triphosphate (ATP) production in RBL-2H3 cells in glucose-free, galactose-containing media (95% confidence interval EC50 = 7.5-9.7 µm), without causing cytotoxicity. Using these same glucose-free conditions, 15 µm TCS dampens RBL-2H3 degranulation by 40%. The same ATP disruption was found with human HMC-1.2 cells (EC50 4.2-13.7 µm), NIH-3 T3 mouse fibroblasts (EC50 4.8-7.4 µm) and primary human keratinocytes (EC50 3.0-4.1 µm) all with no cytotoxicity. TCS increases oxygen consumption rate in RBL-2H3 cells. Known mitochondrial uncouplers (e.g., carbonyl cyanide 3-chlorophenylhydrazone) previously were found to inhibit mast cell function. TCS-methyl, which has a methyl group in place of the TCS ionizable proton, affects neither degranulation nor ATP production at non-cytotoxic doses. Thus, the effects of TCS on mast cell function are due to its proton ionophore structure. In addition, 5 µm TCS inhibits thapsigargin-stimulated degranulation of RBL-2H3 cells: further evidence that TCS disrupts mast cell signaling. Our data indicate that TCS is a mitochondrial uncoupler, and TCS may affect numerous cell types and functions via this mechanism. Copyright © 2015 John Wiley & Sons, Ltd.

Molecular markers in oral lichen planus: A systematic review

Oral lichen planus (OLP) is a chronic inflammatory mucosal disease that is usually detected in 0.5–2.2% of the human population. Among these, only 0.5–2.9% of the lesions progress to carcinoma. However, there are no prognostic markers available presently to recognize the increased risk in malignant transformation of the lesions. Selected markers for cell proliferation, adhesion, apoptosis and lymphocytic infiltration were analyzed by immunohistochemistry in addition to static cytometry for DNA content. The concept linking OLP and oral squamous cell carcinoma states that chronic inflammation results in crucial DNA damage, which further progresses to development of carcinoma. Even though in the past decade, enormous information has been accumulated on malignant potential of OLP, its transformation still remains unclear. Hence, the purpose of this article was to review cellular and molecular markers to understand the pathogenesis of OLP and its progression toward malignancy.

Role of distinct CD4(+) T helper subset in pathogenesis of oral lichen planus

Oral lichen planus (OLP) is one of the most common chronic inflammatory oral mucosal diseases with T-cell-mediated immune pathogenesis. In subepithelial and lamina propria of OLP local lesions, the presence of CD4(+) T helper (CD4(+) Th) cells appeared as the major lymphocytes. These CD4(+) T lymphocytes can differentiate into distinct Th cell types such as Th1, Th2, Treg, Th17, Th22, Th9, and Tfh within the context of certain cytokines environment. Growing evidence indicated that Th1/Th2 imbalance may greatly participate into the cytokine network of OLP immunopathology. In addition, Th1/Th2 imbalance can be regulated by the Treg subset and also greatly influenced by the emerging novel CD4(+) Th subset Th17. Furthermore, the presence of novel subsets Th22, Th9 and Tfh in OLP patients is yet to be clarified. All these Th subsets and their specific cytokines may play a critical role in determining the character, extent and duration of immune responses in OLP pathogenesis. Therefore, we review the roles of distinct CD4(+) Th subsets and their signature cytokines in determining disease severity and susceptibility of OLP and also reveal the novel therapeutic strategies based on T lymphocytes subsets in OLP treatment.

Salivary Interferon Gamma and Interleukin-4 Levels in Patients Suffering from Oral Lichen Planus

Objective

Oral lichen planus (OLP) is a chronic inflammatory disease. Immunological factor may act as etiological factor. The cellular immune cells such as T cells are impor- tant in pathogenesis. Interferon gamma (IFN-γ) and interleukin 4 (IL-4) are secreted by T-helper 1 (Th1) and Th2, respectively. The aim of this study was to investigate the cor- relation between salivary levels of IFN-γ and IL-4 with OLP.

Materials and Methods

This case control study included sixty three Iranian OLP patients who were selected from the Department of Oral Medicine of Ahvaz Jundishapur University of Medical Sciences from January to July 2013. An equal number of healthy volunteers were also selected as a control group. The OLP patients were then divided into two follow- ing sub-groups: reticular (n=30) and erythematous/ulcerative (n=33). All patients had no systemic disease and received no medication. IFN-γ and IL-4 levels in whole unstimulated saliva (WUS) were measured using the enzyme-linked immunosorbent assay (ELISA) test. Data analysis was done using t test, ANOVA, least significant difference (LSD) test, and the Kruskal-Wallis test.

Results

Reticular OLP patients showed higher salivary IFN-γ (7.74 ± 0.09 pg/ml ) and IL-4 (3.876 ± 0.05 pg/ml) levels compared with the control group, indicating that difference was significant. Salivary IFN-γ/IL-4 ratio significantly increased compared with control group (P=0.042). Salivary IFN-γ and IL-4 levels between sub-groups (re- ticular and erythematous/ulcerative) were not significantly different (2.6 ± 0.06 and 2.3 ± 0.05, respectively, P<0.05).

Conclusion

Salivary IFN-γ and IL-4 levels were increased in OLP patients. An increase of salivary IFN-γ/IL-4 ratio in OLP patients showed that Th1 might have a dominant role in the OLP pathogenesis.

Fractal analysis of mucosal microvascular patterns in oral lichen planus: a preliminary study

OBJECTIVES

The objective of this study was to assess local vascular architecture in atrophic-erosive oral lichen planus (OLP).

MATERIALS AND METHODS

We investigated the capillary structure of the oral mucosa in 31 patients with OLP and 32 healthy controls. Capillaries images were captured in vivo through a capillaroscope. We applied fractal analysis to quantify the microvasculature morphometric changes in the oral mucosa of atrophic-erosive OLP patients in terms of their fractal dimension (D).

RESULTS

The oral vascular networks of atrophic-erosive OLP lesions had a significantly higher D, both in buccal mucosae (D=1.167, P=.019) and in tongue (D=1.196, P=.038), compared with the control population (1.123 for both locations, respectively).

CONCLUSIONS

The present study confirms previous literature data on a close relationship between abnormal vascular architecture and atrophic-erosive OLP. Fractal analysis provided a quantitative descriptor of the complexity of the vascular patterns, which increases in the OLP samples. These data may provide new information on the OLP pathogenesis, as well as serve as morphologic quantifiers for monitoring treatment strategies.

Oral lichen planus: an update on its pathogenesis

Oral lichen planus (OLP) is a common T cell-mediated mucocutaneous disease of unknown etiology. A great number of factors have been suggested as relevant to the etiology of this disease. In this article, the authors assemble recent knowledge about the pathogenesis of OLP, discuss some proposed hypotheses, and compare OLP with oral lichenoid lesions.

The master switch: Comparative study of mast cell in oral epithelial dysplasia, oral submucous fibrosis and oral squamous cells carcinoma and their association with inflammation and angiogenesis

Background:

Dental and medical practitioners encounter wide spectrum of oral lesions in their day-to-day practice. Many of the lesions such as leukoplakia, oral submucous fibrosis (OSF), etc., are associated with tobacco and betel nut chewing. Oral leukoplakia, OSF, oral lichen planus and oral squamous cell carcinoma (OSCC) are the most commonly occurring oral diseases associated with characteristic clinical and histological features and are associated with chronic inflammation at some stage of the disease process.

Aims:

To study and compare the number, morphology and topographical distribution of mast cells in oral epithelial dysplasia (OED), OSF and OSCC and to correlate different types of mast cells with the inflammatory infiltrate and vascularity of the lesions.

Materials and Methods:

Total number of subjects was 120 and equally divided into four groups of 30 as controls, OED, OSF and OSCC cases. Two sections of from each tissue embedded in paraffin wax block were made which were stained with hematoxylin and eosin and toluidine blue stain. Mast cells were counted in five different zones.

Results:

In the present study, increased numbers of mast cells were seen in all lesions. The cases with mild, moderate and severe inflammation showed increased number of typical (TMCs), atypical (AMCs) and granular mast cells (GMCs), respectively.

Conclusion:

The result of the present study concludes that the mast cells play a key role in mediating the cross links between external angiogenic agent and local immunologic factors.

Levels of salivary antioxidant vitamins and lipid peroxidation in patients with oral lichen planus and healthy individuals

Oral lichen planus (OLP) is a chronic inflammatory mucosal disease of unknown etiology. Many studies have implicated the protective role of antioxidants in such diseases. The aim of this study was to compare salivary total antioxidant capacity (TAC and malondialdehyde (MDA) and antioxidant vitamin (vitamin s A, C and E) levels in patients with erosive OLP and healthy individuals. Thirty six patients with OLP (14 males, 22 females) and 36 control subjects (15 males, 21 females), matched for age and sex were enrolled in this case control study. The salivary levels of MDA, TAC, and antioxidant vitamin levels were measured in both case and control groups. The salivary level of MDA was significantly higher (p<0.001) in patients than in controls. In patients with OLP, the TAC of saliva was significantly lower than that in healthy subjects (p<0.001). Compared with controls, the levels of salivary antioxidant vitamins were significantly decreased in patients with OLP (p<0.001). In addition, a positive correlation was found between the decrease in the salivary amount of vitamin C and that in vitamin E in patients and controls. In addition to the lower salivary levels of antioxidant vitamins and the lower TAC, the higher level of MDA in patients with OLP suggests that free radicals and the resulting oxidative damage may be important in the pathogenesis of OLP lesions.

Association of cytokine gene polymorphisms with oral lichen planus in Malayalam-speaking ethnicity from South India (Kerala)

Oral lichen planus (OLP) is a chronic mucocutaneous condition that affects the oral mucous membrane as well as skin. It is a chronic cell-mediated autoimmune condition where the T-cell-mediated immune response plays an important part in the pathogenesis by causing damage to basal keratinocytes in oral mucosa. Cytokine gene polymorphisms have an unquestionable role in the orchestration of the immune response, leading to different functional scenarios, which in turn influence the outcome of the disease establishment and evolution. The purpose of this study was to understand the role of these cytokine gene polymorphisms in the tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β), and IL-6 genes with OLP in 101 individuals of Malayalam-speaking ethnicity from South India (Kerala). We further investigated the role of these polymorphisms in patients suffering from OLP with other comorbid factors. Genotyping was carried out by polymerase chain reaction-restriction fragment length polymorphism. The results demonstrate that the A allele in the TNF-α -308 polymorphism could play an important role in the susceptibility to OLP. IL-1β +3954 in OLP was associated with other comorbid factors in both allelic and genotypic combinations. However, when patients suffering from OLP were stratified to understand the involvement of other comorbid factors, we observed that the T and C alleles were independent risk factors for chronic periodontitits and diabetes mellitus. On the other hand, IL-6 -597 did not show any disease association with OLP in the study population. This study indicates that proinflammatory cytokines are an important factor in understanding the disease burden of OLP and their comorbid factors.

Oral lichen planus: focus on etiopathogenesis

Lichen planus is a chronic mucocutaneous inflammatory disease, which frequently affects the oral mucosa of white females over 40 years old. Its aetiology remains uncertain and the pathogenesis is still the object of much speculation. The present paper presents the most well known antigens, and describes the action of different cells and proteins associated with the development of that disease, as well as the possible agents involved with its malignant transformation. Different external agents, especially virus, and internal agents, like stress, and the heat shock protein antigen expression, associated or not, can alter the basal keratinocytes of the oral mucosa making them susceptible to apoptosis by CD8(+) cytotoxic T cell as well as activate matrix metalloproteinase and mast cell degranulation, which produce a great range of inflammatory mediators and cytokines determining the clinical onset of the disease. Regarding carcinogenesis, since it is a complex process and presents multifactorial origin, it is believed that there may be a synergism between intrinsic, such as inflammation mediators, and extrinsic agents (tobacco, alcohol, viral infections) for the OLP malignant transformation to occur. However, further studies are needed to better understand the origin, pathogenesis and process of malignant transformation of OLP.

Role of mast cells in pathogenesis of oral lichen planus

Recent attention has been directed toward the role of mast cells in the pathogenesis of oral lichen planus. Mast cells are responsible for trafficking inflammatory cells into the connective tissue that in turn helps in progression and maintenance of chronicity of oral lichen planus (OLP). OLP is a T-cell-mediated chronic inflammatory oral mucosal disease of unknown etiology, and lesions contain few B-cells or plasma cells and minimal deposits of immunoglobulin or complement. Hence, OLP is ideally positioned for the study of human T-cell-mediated inflammation and autoimmunity. This study was done to evaluate the mast cell count using toluidine blue stain in OLP and compares it with oral lichenoid reaction (OLR), and to propose the possible role of mast cells in the pathogenesis of OLP and OLR. Ten cases each of OLP and OLR and five cases of normal buccal mucosa were taken from the archives of Department of Oral Pathology. The samples were stained with toluidine blue using standard toluidine blue method by Wolman 1971. An increase in mast cell count was observed in OLP and OLR in comparison to normal oral mucosa. However, no significant differences in mast cell count were noted between OLP and OLR.

Degranulated mast cells and TNF-α in oral lichen planus and oral lichenoid reactions diseases

Background:

The objective of this study was to assess mast cells and TNF-α in oral lichen planus (OLP) and oral lichenoid reactions (OLR) patients as diagnostic marker to the differential diagnosis of OLP and OLR diseases.

Materials and Methods:

In this cross-sectional study, samples were obtained from 30 OLP and 30 OLR patients, between June 2010 and March 2011 in Dental clinic of the University of Isfahan, Iran. Mast cells in the reticular layer of the lamina propria for samples were evaluated using toluidine blue method and immunohistochemical technique. The clinical relevant data taken into account were: demographical data, total number and degranulated mast cells, ratio of degranulated mast cells and TNF-α positive degranulated mast cells.

Results:

In OLP and OLR, the total mast cells were 21.2 ± 7.9 and 20.3 ± 6.8, degranulated mast cells were 15.5 ± 6.9 and 19.2 ± 6.9, ratio of degranulated mast cells to total mast cells were 0.716 ± 0.067 and 0.946 ± 0.081, and TNF-α positive degranulated mast cells were 13.6 ± 6.3 and 17.1 ± 6.04, respectively. There was no significant difference for the total mast cells. But degranulated mast cells, ratio of degranulated mast cells and TNF-α positive degranulated mast cells in OLR were significantly higher than OLP patients.

Conclusions:

Our results showed that the degranulated mast cells, ratio of degranulated mast cells and TNF-α in OLR was significantly more than OLP patients and these may be able to be used as diagnostic markers to the differential diagnosis of OLP and OLR.

Prevalence of hepatitis C and hepatitis B virus infection(s) in patients with oral lichen planus

AIM

The aim of this study was to determine the prevalence of hepatitis B virus and hepatitis C virus (HCV) infections in patients with oral lichen planus (OLP) and to compare it with that of general population.

MATERIALS AND METHODS

A total of 60 patients were included in the study. Patients were selected from the outpatient department of Rama Dental College Research Centre, Kanpur, Uttar Pradesh. Thirty patients with OLP were included in Group 1. Thirty age- and sex-matched healthy patients with no history of oral or skin lesions were included in Group 2. Detailed case history, biopsy (the most representative site of the lesion is chosen for specimen), detection of hepatitis B surface antigen (HBsAg), and detection of anti-HCV antibody were carried out.

RESULTS

The serum of the entire study sample (Group 1 and Group 2) was tested for both hepatitis C antibodies and HBsAgs with the enzyme-linked immunosorbent assay (ELISA) test (using the third generation kit). It was found negative for both HBsAgs and hepatitis C antibodies.

CONCLUSION

In the present study, all the samples including OLP patients and healthy patients were seronegative for both hepatitis B (HBsAg) and hepatitis C (HCV antibody).

Pathogenesis of oral lichen planus--a review

Oral lichen planus (OLP) is a T-cell-mediated chronic inflammatory oral mucosal disease of unknown etiology. OLP presents as white striations, white papules, white plaques, erythema, erosions, or blisters affecting predominantly the buccal mucosa, tongue and gingiva. Both antigen-specific and non-specific mechanisms are hypothesized to be involved in the pathogenesis of oral lichen planus (OLP). Antigen-specific mechanisms in OLP include antigen presentation by basal keratinocytes and antigen-specific keratinocyte killing by CD8(+) cytotoxic T cells. Non-specific mechanisms include mast cell degranulation and matrix metalloproteinase activation in OLP lesions. These mechanisms may combine to cause T cell accumulation in the superficial lamina propria, basement membrane disruption, intra-epithelial T cell migration and keratinocyte apoptosis in OLP. The various hypotheses proposed for pathogenesis of oral lichen planus are discussed in this review.

Heat-shock protein expression and topical treatment with tacrolimus in oral lichen planus: an immunohistochemical study

Oral lichen planus (OLP) is a chronic inflammatory mucosal disease of unknown etiology. Usually asymptomatic, the disorder is occasionally complicated by extensive painful erosions. Topical corticosteroids are the mainstay of treatment, but a new topical therapy with tacrolimus has been described previously. The aim of the current study was to examine the expression of heat-shock protein 70 (HSP70) in biopsy specimens from 11 OLP lesions before and after topical treatment with tacrolimus. Immunostaining was performed with anti-HSP70 antibody as the primary layer. Clinically, there was a rapid improvement with topical tacrolimus treatment in 10 out of the 11 patients. The moderate increase in HSP70 expression after treatment with tacrolimus was not significant. It was concluded that topical tacrolimus has no effect on the expression of HSP70 in OLP.

Histochemical analysis of pathological alterations in oral lichen planus and oral lichenoid lesions

Lichen planus is a dermatologic disease of unknown etiology characterized by keratotic plaques on the skin. Many patients also harbor white lesions of the oral mucosa. The literature contains numerous reports of lichen planus-like lesions evolving in conjunction with the administration of a variety of pharmacologic agents. It is difficult, if not impossible, to distinguish such lesions from one another. The present study evaluated the epithelial and basement membrane thickness, mast cells (intact cells and degranulated cells subepithelially) and the presence or absence of blood vessels in oral lichen planus and oral lichenoid lesions. The evaluation was done using the periodic acid-schiff (PAS) and toluidine blue staining techniques on 20 cases each of oral lichen planus and oral lichenoid lesions and 5 control specimens of normal buccal mucosa. The results showed an increased number of degranulated mast cells in areas of basement membrane degeneration, increased vascularity and increased PAS-positive basement membrane thickness in oral lichen planus as compared with oral lichenoid lesions. Reduced epithelial thickness was found in oral lichen planus. The present study emphasizes the importance of these parameters in differentiating oral lichen planus from oral lichenoid lesions using special staining techniques.

Investigation of functional gene polymorphisms interleukin-1β, interleukin-6, interleukin-10 and tumor necrosis factor in individuals with oral lichen planus

Oral lichen planus (OLP) is a chronic inflammatory oral mucosal disease. There are some studies in the literature demonstrating association between cytokines genes polymorphisms and susceptibility to develop some immune-mediate conditions. The purpose of this study was to investigate cytokine gene polymorphisms in a sample of Brazilian patients with OLP. Fifty-three patients with OLP (mean age = 43.1 years; range 20-68 years) and 53 healthy volunteers (mean age = 42.9 years; range 21-67) were genotyped for IL-1beta +3954 (C/T), IL-6-174 (G/C), IL-10-1082 (G/A) and TNFA-308 (G/A) gene polymorphisms. Statistical analysis was based on the use of logistic regression (P-values below 0.05 were considered as significant). IL-6 and TNFA homozygous genotypes were significantly more often detected in OLP patients. These genotypes were associated with an increased risk of OLP development (OR 6.89 and 13.04, respectively). IL-1beta and IL-10 gene polymorphisms were not related to OLP development. Our findings clearly demonstrate an association between inheritance of IL-6 and TNFA gene polymorphisms and OLP occurrence, thus giving additional support for genetic basis of this disease.

Expression profile of chemokines and chemokine receptors in epithelial cell layers of oral lichen planus

BACKGROUND

To understand the immunopathological features of oral lichen planus (OLP), we analyzed the expression of chemokines in the epithelial cell layers.

METHODS

Epithelia from OLP or healthy gingiva were collected by laser microdissection. The chemokine and chemokine receptor expressions in the epithelia were analyzed by DNA microarray.

RESULTS

High levels of MIP-3alpha/LARC/CCL20 and its receptor CCR6 were expressed in the lesional epithelia. Furthermore, DC-CK1/CCL18, ELC/CCL19, SDF-1/CXCL12 and CXCR4 expressions were also increased. Immunohistologial analysis showed that high numbers of Langerhans cells (LCs) were present in the epithelia of OLP. Lesional epithelia also expressed high levels of the ligands specific for CXCR3 (e.g. MIG/CXCL9, IP-10/CXCL10 and I-TAC/CXCL11) and CCR5 (e.g. RANTES/CCL5).

CONCLUSIONS

Infiltration of LCs is orchestrated by CCR6. Further, LCs residing in the lesional epithelia may be a mature phenotype. Moreover, infiltration of T cells in OLP could be mediated by signaling pathways through CXCR3 and CCR5.

Expression of TNF-alpha in oral lichen planus treated with fluocinolone acetonide 0.1%

BACKGROUND

Oral lichen planus (OLP) is a common chronic inflammatory disease involving T cells-mediated immunity. Tumor necrosis factor (TNF)-alpha has been reported to be involved in the disease process. The purpose of this study was to investigate the effect of fluocinolone acetonide in orabase (FAO) 0.1% on the expression of TNF-alpha in patients with OLP.

METHODS

Eighteen Thai patients with atrophic or erosive OLP were recruited. Biopsy specimens were taken before and 1 month after treatment with FAO 0.1% and sent for histopathologic examination where they were immunohistochemically stained with antibody to TNF-alpha. Twenty normal mucosa specimens were identically processed. Oral squamous cell carcinoma tissue was used as a positive control for TNF-alpha expression, whereas OLP sections without primary antibody were served as negative control.

RESULTS

Sixteen of 18 cases (88.89%) of OLP exhibited positive staining for TNF-alpha. Most of the TNF-alpha was observed in the mononuclear cells. Ten cases (55.56%) of OLP demonstrated TNF-alpha expression in keratinocytes. The number of mononuclear cells positive for TNF-alpha before the treatment with FAO 0.1% in orabase was statistically higher than that after the treatment (P=0.000) and in the normal mucosa (P=0.000). Moreover, the number of mononuclear cells after treatment with FAO 0.1% in orabase was statistically lower than before the treatment (P=0.000).

CONCLUSION

Our study exhibited that TNF-alpha may be associated with the immunopathogenesis of OLP in Thai patients and FAO 0.1% had an effect on the reduction of TNF-alpha expression.

The ‐308 Promoter Polymorphism in the Tumour Necrosis Factor Gene in Patients with Lichen Planus

The close chromosomal proximity of major histocompatibility complex and tumour necrosis factor genes may suggest the involvement of the latter in the pathogenesis of immunological diseases associated with HLA antigenes. The major histocompatibility complex antigens may play a certain role in the pathogenesis of lichen planus. Therefore we examined the -308 promoter polymorphism of tumour necrosis factor gene in patients with lichen planus. Sixty-six patients and 66 age- and sex-matched controls participated in the study. Genomic DNA from patients and controls was typed for tumour necrosis factor (-308) polymorphism using an allele-specific polymerase chain reaction. We did not find any correlation between genotype distribution, allele frequency and lichen planus. In our study we failed to observe any association between a genotype and mean level of tumour necrosis factor in plasma of our patients.

Current controversies in oral lichen planus: Report of an international consensus meeting. Part 1. Viral infections and etiopathogenesis

Despite recent advances in understanding the immunopathogenesis of oral lichen planus (LP), the initial triggers of lesion formation and the essential pathogenic pathways are unknown. It is therefore not surprising that the clinical management of oral LP poses considerable difficulties to the dermatologist and the oral physician. A consensus meeting was held in France in March 2003 to discuss the most controversial aspects of oral LP. Part 1 of the meeting report focuses on (1) the relationship between oral LP and viral infection with special emphasis on hepatitis C virus (HCV), and (2) oral LP pathogenesis, in particular the immune mechanisms resulting in lymphocyte infiltration and keratinocyte apoptosis. Part 2 focuses on patient management and therapeutic approaches and includes discussion on malignant transformation of oral LP.

Quantification of mast cells in different stages of human periodontal disease

OBJECTIVE AND METHODS

Among the cells involved in immune and inflammatory responses in periodontal disease, mast cells have been shown to be capable of generating a large number of biologically active substances. The present study was undertaken to identify and quantify the presence of mast cells in different stages of human periodontal disease using histochemical (toluidine blue) and immunohistochemical (tryptase-positive mast cells) techniques.

RESULTS

Mast cell densities (cells per mm(2)) were significantly increased in chronic periodontitis/gingivitis lesions compared with clinically healthy gingival tissues (Health) uniquely by immunohistochemical technique. Interestingly, mast cells were distributed specially in close apposition to mononuclear cells.

CONCLUSIONS

In human periodontal disease there is an increase in the number of mast cells that may be participating either in the destructive events or in the defense mechanism of periodontal disease via secretion of cytokines, including perpetuation of the Th2 response, and cellular migration and healing processes.

Apoptosis and cell cycle arrest in oral lichen planus Hypothesis on their possible influence on its malignant transformation

The quantitative importance of cell cycle arrest and apoptosis mechanisms in oral lichen planus (OLP) was analysed in order to assess the cell response to T lymphocyte aggression and establish a hypothesis on the influence of these phenomena in the malignant transformation process. The TUNEL assay and immunohistochemical methods were used to detect caspase-3, bax, and p21 in 32 tissue samples of oral mucosa with OLP and in 20 samples of normal oral mucosa. Positivity for TUNEL, caspase-3 and p21 was significantly more frequent in cases than in controls (p<0.001). Both TUNEL and caspase-3 positivity was significantly greater in the basal versus suprabasal layer (p=0.004 and 0.052, respectively). The basal and suprabasal expression of p21 was significantly higher in cases with a more intense liquefaction degeneration (p<0.01). There was no significant difference in basal expression of bax between cases and controls. The quantitative importance of apoptosis was small in OLP. Epithelial cells attacked in OLP have a very low response to apoptosis and cell cycle arrest mechanisms, which may produce an epithelial substrate that favours malignant transformation.

The role of perforin-mediated apoptosis in lichen planus lesions

Lichen planus is recognized as a T-cell-mediated disease. Histologically, it is characterized by the formation of colloid bodies representing apoptotic keratinocytes. The apoptotic process mediated by CD8(+) cytotoxic T lymphocytes (CTLs) and NK cells mainly involves two distinct pathways: the perforin/granzyme pathway and the Fas/FasL pathway. So far, little is known regarding the role of perforin-mediated apoptosis in lichen planus. In the present study, the expression and distribution of perforin, T and NK cell subsets in the epidermis and dermis of lesional and nonlesional lichen planus skin were studied. Skin biopsy specimens from lesional and nonlesional skin of ten patients with lichen planus and eight healthy persons were analysed by immunohistochemistry. Significant accumulation of T cells, particularly of CD4(+) and CD8(+) subsets, was found in both epidermis and dermis of lichen planus lesions compared with nonlesional and healthy skin. There were no significant differences in the incidence of NK cells (CD16(+) and CD56(+)) between lesional, nonlesional and healthy skin. Perforin expression was significantly upregulated in the epidermis of lichen planus lesions. In conclusion, accumulation of perforin(+) cells in the epidermis of lichen planus lesions suggest a potential role of perforin in the apoptosis of basal keratinocytes.

A new delivery system of clobetasol-17-propionate (lipid-loaded microspheres 0.025%) compared with a conventional formulation (lipophilic ointment in a hydrophilic phase 0.025%) in topical treatment of atrophic/erosive oral lichen planus. A Phase IV, randomized, observer-blinded, parallel group clinical trial

BACKGROUND

Topical application of clobetasol-17-propionate has been diffusely reported as an efficacious therapy in atrophic/erosive oral lichen planus (OLP), without exposing the patient to systemic side-effects. However, prolonged contact and respective topical effects on the oral mucosa should be avoided.

OBJECTIVES

The aim of the present study was to evaluate efficacy and compliance of new lipid microspheres loaded with 0.025% of clobetasol propionate (formulation A) compared with a commonly used formulation (a sort of dispersion of a lipophilic ointment in a hydrophilic phase) with the same amount of drug (formulation B) in the topical treatment of OLP.

PATIENTS AND METHODS

Fifty patients with symptomatic OLP were enrolled in a controlled single-blind phase IV clinical trial. After a dropout of five patients, a total of 45 patients [12 males and 33 females; mean age 61.1 years (+/- 12.3 SD; range 25-82)] were treated (17 with formulation A and 28 with formulation B, matched for gender and age; P > 0.2) with the same dosage regimen. At times T0, T1 and T2 we evaluated the following parameters: (i) pain score (by linear visual analogue scale; 0-100); (ii) clinical score; (iii) clinical resolution; and (iv) patient compliance. Statistical analysis was calculated using S-Plus 4.0 and SPSS 9.0 (Student's t-test, chi(2), Kolmogorov-Smirnow, Friedman, Student-Newman-Keuls, Mann-Whitney U-test and Spearman tests).

RESULTS

Both formulations were found to be similar for parameters ii, iii and iv, although with a better general trend for formulation A; a significant difference was registered for formulation A in terms of a reduction in painful symptoms (parameter i) at time T2 (P = 0.02).

CONCLUSIONS

Our results suggest that the new topical drug delivery system (formulation A) may enhance, at least in terms of symptom remission and compliance, the effectiveness of clobetasol propionate at a dose of 0.025% in OLP therapy.

Mast cells and oral inflammation

Mast cells are mobile granule-containing secretory cells that are distributed preferentially about the microvascular endothelium in oral mucosa and dental pulp. The enzyme profile of mast cells in oral tissues resembles that of skin, with most mast cells expressing the serine proteases tryptase and chymase. Mast cells in oral tissues contain the pro-inflammatory cytokine tumour necrosis factor-alpha in their granules, and release of this promotes leukocyte infiltration during evolving inflammation in several conditions, including lichen planus, gingivitis, pulpitis, and periapical inflammation, through induction of endothelial-leukocyte adhesion molecules. Mast cell synthesis and release of other mediators exerts potent immunoregulatory effects on other cell types, while several T-lymphocyte-derived cytokines influence mast cell migration and mediator release. Mast cell proteases may contribute to alterations in basement membranes in inflammation in the oral cavity, such as the disruptions that allow cytotoxic lymphocytes to enter the epithelium in oral lichen planus. A close relationship exists among mast cells, neural elements, and laminin, and this explains the preferential distribution of mast cells in tissues. Mast cells are responsive to neuropeptides and, through their interaction with neural elements, form a neural immune network with Langerhans cells in mucosal tissues. This facilitates mast cell degranulation in response to a range of immunological and non-immunological stimuli. Because mast cells play a pivotal role in inflammation, therapies that target mast cell functions could have value in the treatment of chronic inflammatory disorders in the oral cavity.