Pathogenesis Of Oral Lichen Planus Research Articles

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.

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.

Diagnostic profiling of salivary exosomal microRNAs in oral lichen planus patients.

Oral lichen planus is a chronic inflammatory oral mucosal disease whose exact cause is unclear and which requires efficient diagnostic and therapeutic strategies. Identification of disease-specific biomarkers in saliva is an easy, quick, and non-invasive approach for molecular diagnosis. This study was designed to examine salivary exosomal microRNAs (miRNAs) that could be candidates for diagnosing and elucidating the pathogenesis of oral lichen planus. We compared miRNA profiles of salivary exosomes of patients with oral lichen planus with those of healthy controls. Saliva samples from 16 patients with oral lichen planus and eight healthy controls were divided into two sets and examined using miRNA microarray analysis and TaqMan quantitative PCR. The three miRNAs identified (miR-4484, miR-1246, and miR-1290) were further validated. Of these, miR-4484 was significantly upregulated in the salivary exosomes of patients with oral lichen planus. This study thus identifies a potential miRNA biomarker for oral lichen planus and provides insight into the functions of miRNAs in the pathogenesis of oral inflammatory diseases.

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

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. 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. 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). 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.

Expression of E-cadherin in oral lichen planus.

Oral lichen planus (OLP) is a common lesion of the oral mucosa that can progress to cancer. E-cadherin is involved in intercellular adherence and the pathogenesis, development and metastasis of tumors, and is considered to be an important indicator of tumor progression and prognosis. The aim of this study was to investigate the expression of E-cadherin in OLP in order to elucidate its role in the pathogenesis and malignant transformation of OLP and provide evidence to support the early diagnosis and treatment of OLP with malignant potential. OLP specimens (n=52) and samples of normal oral mucosa (n=41) as the control were collected. Immunohistochemical staining was conducted to reveal the expression of E-cadherin in the OLP samples and normal oral mucosa. It was observed that 25 of the 52 OLP specimens exhibited normal positive expression of E-cadherin and 27 exhibited abnormal positive expression, corresponding to an abnormal positive rate of 51.92%. In the normal oral mucosa group, 39 of the 41 cases exhibited normal positive expression and 2 exhibited abnormal positive expression. The abnormal positive rate in the normal oral mucosa was 4.88%, which was significantly lower than that in the OLP group. The significantly elevated rate of abnormal positive expression of E-cadherin in the OLP group indicates the involvement of E-cadherin in the malignant transformation of OLP and supports the malignant potential of OLP.

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

The objective of this study was to assess local vascular architecture in atrophic-erosive oral lichen planus (OLP). 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). 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). 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 Tcell-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 positive correlation of the CCL2-CCR2 axis with the disease activity may indicate the fundamental role in the pathogenesis of oral lichen planus.

The important roles of CCL2 and its receptor CCR2 had been reported in a series of inflammatory disorders. However, few studies investigated the potential role of CCL2/CCR2 axis in oral lichen planus (OLP). Therefore, this study aimed to detect the expression of CCL2 and CCR2 in OLP lesions and compare their changes before and after treatment. CCL2 and CCR2 expression was investigated using immunohistochemical staining and real-time RT-PCR in 32 patients with OLP and eight controls. Moreover, changes in their expression after treatment with triamcinolone acetonide were assessed in lesions from three patients. CCL2+ and CCR2+ cells were few in the controls and remarkably increased in the epithelial and subepithelial layers of lesions (n = 32, all P < 0.001). However, the densities of CCL2+ and CCR2+ cells were not significantly different between reticular (n = 12) and erythematous/erosive lesions (n = 20), although they significantly decreased after treatment (627.7 ± 108.2 vs. 258.3 ± 148.3, P = 0.017; 1034.7 ± 74.6 vs. 648 ± 77.6, P = 0.003, respectively). CCL2+/CCR2+ cell numbers were positively correlated with disease activity (correlation coefficient, 0.588; P < 0.001; correlation coefficient, 0.409; P = 0.02, respectively). The results of this study indicated that the CCL2-CCR2 axis was involved in the pathogenesis of OLP and was positively correlated with disease activity.

Comparison of Serum Autoantibodies to Desmogleins I, III in Patients with Oral Lichen Planus and Healthy Controls.

Lichen planus is a mucocutaneous disease which is relatively common and in 30-70% of patients, mucosal lesions can be seen and known as a precancerous lesion but its etiology is not completely understood. Desmogleins I and III are the main desmosomal transmembrane proteins. These proteins have been identified as the autoantigen of the autoimmune disease. The aim of this study was evaluation of serum autoantibodies against desmogleins Ι, ΙΙΙ in oral lichen planus . We attempted to determine the etiology of this disease with evaluation of these serum factors. Thirty-five patients with oral lichen planus and 35 healthy controls were recruited and tested for serum autoantibodies against desmogleins Ι, ΙΙΙ and indirect immunofluorescence also performed. Data were analyzed by statistical-analytical methods (Independent sample t -test) with using the SPSS.15 software. Serum autoantibody against desmoglein Ι had no significant difference in the two groups ( P =0.31 ) but significant increase in serum autoantibody to desmoglein ΙΙΙ was found in patients with oral lichen planus ( P =0.00) . It seems that autoantibody against desmoglein III has a significant role in the pathogenesis of oral lichen planus.

A Study of Association Between Oral Lichen Planus and Immune Balance of Th1/Th2 Cells.

The aims of this study are to investigate the key role of Th1 and Th2 in the pathogenesis of oral lichen planus (OLP) and to explore the possible association between OLP and immune balance of Th1/Th2 cells. We selected 35 patients diagnosed with OLP and 35 age- and sex-matched controls as subjects. The expressed level of interferon-gamma (IFN-γ) and interleukin-4 (IL-4) and the characteristic cytokines of Th1 and Th2 were assayed in the serum of peripheral blood of the patients. The lesional tissue of the two groups was investigated with the methods of double immunofluorescence. The ratio of Th1/Th2 was evaluated, and the difference of the results between serum and lesional tissue was compared. Both IFN-γ and IL-4 levels increased in the serum and lesional tissue compared with those of the controls (P < 0.001, P = 0.030, P < 0.001, and P < 0.001) and IFN-γ/IL-4 ratio of OLP patients, which increased significantly (P = 0.001 and P = 0.003). The difference between serum and lesional tissue was obviously insignificant (P = 0.982). Th1 cytokine predominance was proven in this research on Chinese subjects. Th1 cells may play leading roles on Th1/Th2 immune balance to pathogenesis of OLP.

The Activation of NF-κB in Infiltrated Mononuclear Cells Negatively Correlates with Treg Cell Frequency in Oral Lichen Planus.

Oral lichen planus (OLP) is a T cell-mediated chronic inflammatory mucosal disease with persistent accumulation of T cells in the lamina propria. Nuclear factor-kappa B (NF-κB) is a major regulator of immune responses, and NF-κB-dependent cytokines and pro-inflammatory mediators can be detected in higher levels in the saliva and serum from patients with OLP. CD4(+)CD25(+)Foxp3(+) regulatory T (Treg) cells play an important role in the prevention of autoimmune pathology by regulating the immune response. To explore the correlation between NF-κB p65 activation and accumulation of Treg cells in patients with OLP, 40 ethnic Chinese patients with OLP and 10 healthy volunteers were recruited. The nuclear expression of NF-κB p65 in infiltrated mononuclear cells and Treg cells in the OLP lesion and the normal oral mucosa (NOM) was analyzed by immunohistochemistry assay. Our results showed that both the nuclear expression of NF-κB p65 and the number of Foxp3(+) Treg were higher in the OLP lesions. Furthermore, the frequency of Treg cells was negatively correlated with NF-κB nuclear expression in subepithelial lymphocytic infiltrate of the OLP lesion. This finding provides a new insight into the pathogenesis of OLP and may contribute to novel therapeutic strategies for the treatment of OLP by modulating the immune system.

Role of human papilloma virus-16 in the pathogenesis of oral lichen planus – an immunohistochemical study

Oral lichen planus (OLP) is a common chronic inflammatory immune-mediated disease with an aetiopathogenesis associated with cell-mediated immunological dysfunction. It is possible that oral mucosal viral infections, including human papilloma virus-16 (HPV-16) infection, may have a causative role in OLP pathogenesis. To assess the prevalence of HPV-16 in histopathologically diagnosed specimens of OLP and to evaluate whether any clinical features (such as the localisation of specimens) or the age or gender of patients, are correlated with the presence of this virus. This study was conducted on 30 specimens with a histopathological diagnosis of OLP, using the immunohistochemical marker HPV-16. Thirty normal oral mucosa specimens were also included as controls. Brown nuclear staining was accepted as positive for the HPV-16 antibody. The results were analysed using Fisher's exact test. P values<0.05 were considered to be significant. Significant correlation (P=0.0001) was observed between HPV-16 infection and samples with OLP. No statistical conclusions could be drawn regarding age, gender, localisation and HPV-16 positivity. Our study showed that HPV-16 may play a role in the pathogenesis of OLP. Taking into account the oncogenic potential of HPV-16, patients with OLP should be screened for the presence of this virus.

Regulation of immune cells in oral lichen planus.

Oral lichen planus (OLP) is an immunological disease and while it is understood that the T cell subsets, FoxP3(+) Tregs and IL17(+) Th17 cells are involved in immune regulation, little is known about their presence in OLP. The aims of this study were to compare the number of cells expressing FoxP3 or IL-17 in OLP with non-specifically inflamed oral mucosa and to determine which cell types expressed FoxP3 and/or IL-17 and their distribution. Immunohistochemistry was used to investigate the presence of FoxP3(+) or IL-17(+) cells in 12 control cases and 17 cases of OLP. These results were analysed quantitatively and qualitatively. Double-labelling immunofluorescence (IF) was used to determine the type of cell expressing FoxP3/IL-17 and these results were analysed qualitatively. OLP displayed significantly more FoxP3(+) cells (mean 79.3 vs. 20.6 cells/defined area, p < 0.0001) and fewer IL-17(+) cells (mean 1.05 vs. 3.30 cells/defined area, p = 0.0003) than non-specific inflammatory cases. The majority of FoxP3(+) cells were in the sub-epithelial infiltrate, while IL-17(+) cells were deeper in the stromal tissues. IF showed that FoxP3(+) cells co-localised with T cells, while the IL-17(+) cells did not. These results show that the balance between Tregs and IL-17(+) cells is altered in OLP, thus supporting the proposition that disturbance in local immune regulation is important in the pathogenesis of OLP. The observation that the IL-17(+) cells were mast cells has not previously been reported in OLP and again raises questions about the role of mast cells in this condition.

Peripheral and Local Human Papillomavirus 16–Specific CD8+ T-Cell Expansions Characterize Erosive Oral Lichen Planus

Erosive oral lichen planus (OLP) is a chronic, disabling mucocutaneous dysimmune rare disease characterized by mucosal inflammatory erosive lesions with pathological evidence for a marked CD8+ cytotoxic T-lymphocyte (CTL) infiltration. However, the specificity of lesional CTL in OLP has never been analyzed. To investigate the molecular mechanisms underlying dysregulation of T-cell immune responses in patients with OLP, we studied the diversity and antigen specificity of the TCR expressed by CD8+ T cells using dextramer staining, spectratyping, and TCR sequencing in 10 OLP patients undergoing extracorporeal photochemotherapy. Expansions of TCRVβ3-bearing CD8+ T cells were found in peripheral blood and in lesional tissues of OLP patients. Spectratyping and sequencing studies identified specific clonotypes in each patient. These expansions were enriched with human papillomavirus 16 (HPV16)-specific CD8+ T cells in HLA-A*0201+ patients as shown by their immune recognition of the E711-20 immunodominant epitope. Under treatment with extracorporeal photochemotherapy, clonotypic CD8+ T-cell expansions decreased in parallel with clinical remission. Altogether, these data establish a link between HPV infection and OLP pathogenesis by identifying a massive clonal expansion of CD8+ T cells with increased frequency of HPV 16-specific CD8+ T cells in OLP patients.

The TF-miRNA Coregulation Network in Oral Lichen Planus.

Oral lichen planus (OLP) is a chronic inflammatory disease that affects oral mucosa, some of which may finally develop into oral squamous cell carcinoma. Therefore, pinpointing the molecular mechanisms underlying the pathogenesis of OLP is important to develop efficient treatments for OLP. Recently, the accumulation of the large amount of omics data, especially transcriptome data, provides opportunities to investigate OLPs from a systematic perspective. In this paper, assuming that the OLP associated genes have functional relationships, we present a new approach to identify OLP related gene modules from gene regulatory networks. In particular, we find that the gene modules regulated by both transcription factors (TFs) and microRNAs (miRNAs) play important roles in the pathogenesis of OLP and many genes in the modules have been reported to be related to OLP in the literature.

Expression of miRNA-155 and miRNA-146a in peripheral blood mononuclear cells and plasma of oral lichen planus patients

To investigate the expression and clinical significance of miRNA-155 and miRNA-146a in peripheral blood mononuclear cells (PBMC) and plasma of oral lichen planus (OLP) patients. Twenty-five female and seven male OLP patients (OLP group) aged 25 to 54 years were selected from January 2012 to May 2013. The diagnosis was confirmed by pathology and the lesions were divided into two non-erosive OLP group (18 cases) and erosive OLP group (14 cases). Twenty healthy sex and age matched volunteers served as control. miRNA-155 and miRNA-146a expressions in PBMC and plasma were examined by real-time PCR. The difference between OLP group and control group was statistically analyzed. The expressions of PBMC and plasma miRNA-155 were higher in OLP patients than those in the healthy control (median, 0.07 vs 0.03, P < 0.05; 5.84 vs 1.32, P < 0.01). The median expression level of miRNA-146a in PBMC and plasma of OLP patients and healthy controls were (1.26 vs 0.58, P < 0.05) and (412.60 vs 238.42, P < 0.01). The plasma miRNA-155 and miRNA-146a expressions were significantly higher in erosive OLP group than those in non-erosive OLP group. There were no significant differences in the expression of PBMC miRNA-155 and miRNA-146a between the two groups. The expressions of PBMC and plasma miRNA-155 and miRNA-146a are higher in OLP patients. The expressions of plasma miRNA-155 and miRNA-146a are associated with OLP severity. The over expression of miRNA-155 and miRNA-146a in OLP may play a role in the pathogenesis of OLP.

A Comparative Immunohistochemical Analysis of Langerhans Cells in Oral Mucosa, Oral Lichen Planus and Oral Squamous Cell Carcinoma.

Langerhans cells (LCs) are immunocompetent cells resident within oral mucosa which, together with intraepithelial lymphocytes, play a role in mucosal defence. LCs play a role in the pathogenesis of Oral lichen planus (OLP), a chronic mucocutaneous disorder thought to result from cell-mediated immune damage. In oral squamous cell carcinoma (OSCC), LCs are thought to present tumour antigens to the lymphocytes. To assess and compare LCs immuno-histochemically in normal mucosa, oral lichen planus and oral squamous cell carcinoma using anti S100 antibody and to know whether LCs play any role in local immune response to these diseases. The study was carried out in 65 cases (study group), 30 oral lichen planus and 35 oral squamous cell carcinoma (15 well differentiated, 14 moderately differentiated and 6 poorly differentiated), that were randomly selected from the archives of department of oral pathology and along with control group consisting of 30 normal healthy mucosa. The tissue sections were stained immunohisto-chemically by using anti S100 antibody in each group for detection of LCs. There was significant change in mean value of number of LCs in the study groups i.e. OLP and OSCC when compared to that of control group. The results of our study also revealed that there was decrease in the mean value of langerhans cells as the tumour progressed from well differentiated squamous cell carcinoma to poorly differentiated LCs carcinoma. A better understanding and clarity of LCs is pivotal for designing novel or improved therapeutic approaches that will allow proper functioning of LC's in patients with OLP and OSCC, thus significantly reducing the morbidity of OLP and OSCC patients.

Salivary humoral changes in oral bullous lichen planus

Background: To investigate the salivary humoral mechanisms in patients with bullous lichen planus, in the phases of exacerbation and remission. Material and Method: Nineteen patients with bullous oral lichen planus were followed. Saliva was collected in the morning without stimulation in the amount from 5-10 cm2. The determination of immunoglobulins, C3 and C4 in the saliva was performed using the micro-ELISA technique. The circulating immune complexes in the serum and saliva were determined by the PEG method. The results were compared with a control group and within the group in the phases of exacerbation and remission. The results were statistically processed by Student's t - test . Results: Salivary IgA showed a significant decrease, whereas IgG and IgM significantly increased. The values of immunoglobulin A, G and M in the phase of remission were significantly increased compared with the control group. By comparing salivary immunoglobulins in the phases of exacerbation and remission, identical amounts of IgG in both stages of the disease were observed. However, considerably elevated values of IgA and slightly significant increase in the values of IgM were noted. CIC values in the control group and in patients ' group in the phases of exacerbation and remission were increased. Data suggest a highly significant depression of C3 component in the exacerbation phase, while in remission a slightly significant decrease was evident. Complement component C4 in the remission phase compared with a control group was declined. Conclusion: There is an evident involvement of certain saliva components in the pathogenesis of oral lichen planus, but the final predominance of humoral mechanisms in the pathogenesis of bullous lichen planus does not exist yet.

Role of serum interleukin-6 in deciding therapy for multidrug resistant oral lichen planus.

Background Oral lichen planus (OLP) is a T cell mediated immune response. T cells locally present in the involved tissues release cytokines like interleukin-6 (IL-6), which contributes to pathogenesis of OLP. Also IL-6 has been associated with multidrug resistance protein (MRP) expression by keratinocytes. Correspondingly, upregulation of MRP was found in OLP. We conducted this study to evaluate the effects of various drugs on serum IL-6 in OLP; and correlation of these effects with the nature of clinical response and resistance pattern seen in OLP lesions with various therapeutic modalities. Thus we evaluated the role of serum IL-6 in deciding therapy for multidrug resistant OLP. Material and Methods Serum IL-6 was evaluated in 42 erosive OLP (EOLP) patients and 10 normal mucosa and 10 oral squamous cell carcinoma cases using ELISA technique. OLP patients were randomly divided into 3 groups of 14 patients each and were subjected to Pimecrolimus local application, oral Mycophenolate Mofetil (MMF) and Methotrexate (MTX) alongwith Pimecrolimus local application. IL-6 levels were evaluated before and after treatment. Results Serum IL-6 levels were raised above 3pg/ml in 26.19% erosive OLP (EOLP) cases (mean- 3.72±8.14). EOLP (5%) cases with IL-6 levels above 5pg/ml were resistant in MTX group. However significant decrease in serum IL-6 corresponding with the clinical resolution was seen in MMF group. Conclusions Significantly raised IL-6 levels in EOLP reflect the chronic inflammatory nature of the disease. As serum IL-6 levels significantly decreased in MMF group, correspondingly no resistance to treatment was noted. However with MTX there was no significant decrease in IL-6 and resistance to treatment was noted in some, especially plaque type lesions. Thus IL-6 can be a possible biomarker in deciding the best possible therapy for treatment resistant OLP. Key words:Lichen planus, biological markers, cytokines, enzyme-linked immunosorbent assay, immunosuppressive agents.

Thickness of the epithelium and the inflammatory cell infiltrate in oral lichen planus. A morphometric study

Abstract Background Oral lichen planus is a chronic mucocutaneous disease of uncertain etiology. Inflammatory cell infiltrate plays an important role in pathogenesis of oral lichen planus. It is said that hyperplastic epithelium is seen where the inflammatory cell infiltrate is mild while beneath atrophic epithelium dense inflammatory cell infiltrate is evident. Studies have shown negative correlation between thickness of the epithelium and thickness of inflammatory cell infiltrate. Morphometric studies in oral lichen planus are very scanty and have been performed using stage micrometer and eye piece graticule. Using Image Analysis Software can avoid inter-observer variations which has not been done till date. Aim and Objectives The present study aimed at evaluating thickness of epithelium and thickness of inflammatory cell infiltrate and to determine any existing relation between the same using Image Analysis Software. Other histopathologic features were also evaluated. Materials and method 58 confirmed cases of oral lichen planus from buccal mucosa were retrieved from department archives. 6μ thick sections were stained with Hematoxylin and Eosin. Six non-overlapping fields were selected randomly from each section and photomicrographs were captured under 4x objective using Trinocular Research Microscope. Morphometry was done using Image Analysis Software and data was stored in Microsoft excel for statistical analysis. Results In present study the mean of epithelium thickness was 281.2059 and inflammatory cell infiltrate thickness was 330.2540. An inverse correlation was observed. As the thickness of inflammatory cell infiltrate increased there was a decrease in thickness of epithelium (Coefficient -0.156). Conclusion Thickness of the epithelium may vary according to the site, however in this study all cases were from buccal mucosa. Inflammatory cell infiltrate influences overlying thickness of epithelium and determines its nature. How to cite this article Ramya VV, Nandini DB, Praveen SB, Madhushankari GS. Thickness of the epithelium and the inflammatory cell infiltrate in oral lichen planus. A morphometric study. CODS J Dent 2014;6;78-82