Erythematous and reticular forms of oral lichen planus and oral lichenoid reactions differ in pathological features related to disease activity

Emerging potential of phototherapy in management of symptomatic oral lichen planus: A systematic review of randomised controlled clinical trials

Phototherapy incorporating photobiomodulation therapy and antimicrobial photodynamic therapy has been utilised as antioxidants in symptomatic oral lichen planus (OLP) management; however, its role of intervention remains controversial. The aim of this systematic review of CRD42021227788 PROSPERO (an international prospective register of systematic reviews in health and social care) registration number was to oversee and determine phototherapy efficacy in patients with symptomatic OLP, identifying and bridging the literature gaps by proposing recommendations for future studies. A search strategy was developed in consistent with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Various electronic databases were exercised to search for randomised controlled clinical trials (RCTs). Several search engines were employed to analyse a total of 177 studies of which nine included. A wide range of utilised laser and light-emitted diode wavelengths between 630 and 808 nm and irradiance ranged between 10 and 13 mW/cm² were noted. 67% of studies reported a high risk of bias and a high heterogeneity obtained from numerical data for quantitative analysis, therefore meta-analysis was impossible to conduct. Despite inconsistency and diversity in phototherapy parameters, treatment protocols, photosensitiser (type, concentration and method of application) and outcome assessment tools, the majority of the studies showed positive results compared with standard care treatments. Hence, a necessity to perform well-designed RCTs with robust methodology is warranted, after acknowledging the current drawbacks and addressing the suggested recommendations highlighted in our review. Moreover, advanced knowledge in understanding further phototherapy-antioxidants molecular mechanistic in symptomatic OLP is required.

Metabolomics analysis of oral mucosa reveals profile perturbation in reticular oral lichen planus

BACKGROUND

Oral lichen planus (OLP) is a chronic inflammatory mucosal disorder and potentially oral premalignant lesion affecting the stratified squamous epithelia. In OLP, reticular type is the most common clinical form of the disease. However, little is known about it. Metabolomics analysis may help to investigate the disease pathogenesis and to improve clinical treatment.

METHODS

Liquid chromatography (LC)-mass spectrometry (MS) system, XCMS software, SIMCA software, and OSI / SMMS software were integrated to identify differentially expressed metabolites for the pathways and pathology analysis.

RESULTS

Totally, 21 modulated metabolites were identified, whose dysregulations affected 30 metabolic pathways. Through an impact-value screen (impact-value>0.1), 8 pathways were selected as the significantly dysregulated pathways. Pathological network showed that these metabolites participated in 5 pathological processes, that is, inflammatory lesion, DNA damage and repair disorder, apoptosis process, oxidative stress injury, and abnormal energy expenditure.

CONCLUSION

The study revealed the metabolic perturbation of oral mucosa in reticular OLP, which may provide an important reference for the understanding of the pathogenesis of the disease and the discovery of therapeutic targets.

Histopathological characterization of the oral lichenoid disease subtypes and the relation with the clinical data

BACKGROUND

The aim of the study was to analyze the histopathological characteristics of samples with a diagnosis of oral lichenoid disease (OLD) and their link with the location and the type of clinical lesion, and the clinicopathological subtypes.

MATERIAL AND METHODS

Retrospective study on 85 consecutive patients diagnosed with OLD (58 women and 27 men, mean age of 57.7 years). Clinical and histopathological characterization of each case (modified WHO criteria). Collection of the clinical and histopathological data of the lesions. Descriptive and comparative statistical analysis of the results.

RESULTS

The 78.8% of the cases were considered clinically typical while the 21.2% were considered compatible. Histologically, 52.9% were classified as typical and 47.1% as compatible. Biopsies from "plaque-like" lesions presented hyperkeratosis (p>0.001) and epithelial dysplasia (p=0.06) more frequently. Furthermore, acute inflammation was more evident in erosive-ulcerative lesions (p=0.001). Differences regarding the location of the biopsy were statistically non-significant. However, 42.9% of the tongue biopsies showed epithelial dysplasia.

CONCLUSIONS

The histopathological aspect of this disorder is not specific and does not allow us to differentiate between the main subtypes. Therefore, the main reasons to perform a biopsy in this disorder are to define the differential diagnosis and to rule out epithelial dysplasia or a carcinoma. The final histopathological result may be subject to the type of lesion that is biopsied.

Gene expression of miRNA-138 and cyclin D1 in oral lichen planus

OBJECTIVES

This study aimed to evaluate microRNA-138 (miR-138) gene expression and its target cyclin D1 (CCND1) gene and protein expression in oral lichen planus (OLP) mucosa in an attempt to investigate their possible roles in OLP immunopathogenesis.

METHODS

Sixty oral biopsy specimens were harvested from 30 healthy subjects and 30 OLP patients, subdivided into reticular, atrophic, and erosive groups (n = 10 each). Samples were subjected to quantitative real-time polymerase chain reaction analysis for quantification of miR-138 and CCND1 relative gene expression and immunohistochemical analysis to determine CCND1 protein expression.

RESULTS

Samples from OLP patients had a significant underexpression of miR-138 gene and overexpression of CCND1 at both gene and protein levels compared to normal mucosa samples. The lowest levels of miR-138 expression were observed in atrophic and erosive OLP compared to reticular OLP, and the highest levels of CCND1 gene and protein expression were in atrophic OLP. An inverse correlation was demonstrated between the miR-138 expression and both CCND1 gene and protein expression in OLP patients. A significant positive correlation between CCND1 gene and protein expression was also observed.

CONCLUSION

Downregulation of miR-138 increases the gene and protein expression of its potential target CCND1 in OLP mucosa which might have a pivotal role in the disease pathogenesis.

CLINICAL RELEVANCE

This research implied that miR-138 may have a role in identification of symptomatic OLP lesions. MiR-138 might be considered as a potential tool in future OLP molecular therapy.

Using the BITOLA system to identify candidate molecules in the interaction between oral lichen planus and depression

Exacerbations of oral lichen planus (OLP) have been linked to the periods of psychological stress, anxiety and depression. The specific mechanism of the interaction is unclear. The aim of this study was to explore the candidate genes or molecules that play important roles in the interaction between OLP and depression. The BITOLA system was used to search all intermediate concepts relevant to the "Gene or Gene Product" for OLP and depression, and the gene expression data and tissue-specific gene data along with manual checking were then employed to filter the intermediate concepts. Finally, two genes (NCAM1, neural cell adhesion molecule 1; CD4, CD4 molecule) passed the follow-up inspection. By using the text mining can formulate a new hypothesis: NCAM1 and CD4 were identified as involved or potentially involved in the interaction between OLP and depression. These results offer a new clue for the experimenters and hold promise for developing innovative therapeutic strategies for these two diseases.

Phenotypically non-suppressive cells predominate among FoxP3-positive cells in oral lichen planus

BACKGROUND

Oral lichen planus (OLP) is a common T-cell-dominated oral chronic inflammatory disease occurring in periods of remission, quiescence, activity with pronounced inflammation, and acute ulceration. Cell infiltrates in OLP contain varying numbers of CD4⁺ T cells expressing the transcription factor FoxP3. FoxP3⁺ CD4⁺ T cells are, however, a heterogeneous cell population containing suppressive and non-suppressive cells, and their distribution in infiltrates from OLP is unknown.

METHODS

Biopsies were taken from normal oral mucosa (n = 8) and OLP lesions (n = 19), and a set of in situ methods for the determination of the functional phenotype of FoxP3⁺ CD4⁺ T cells was applied.

RESULTS

Numbers of FoxP3⁺ CD4⁺ T cells were highest in the atrophic form of the disease, yet low in the ulcerative form. The main FoxP3⁺ CD4⁺ T-cell population observed was FoxP3⁺ CD45RA^- CD25⁺ CD45RO⁺ and CD15s^- , a phenotype delineating a non-suppressive subset. Numbers of cells with an actively suppressing phenotype (FoxP3⁺ CD45RA^- CD25⁺ CD45RO⁺ and CD15s⁺ ) were, however, about twice as high in reticular lesions as compared with the atrophic form. Many FoxP3⁺ CD4⁺ T cells expressed T-bet, the hallmark transcription factor for IFN-γ-producing T cells, indicating that they may enhance immune and inflammatory responses rather than suppress them.

CONCLUSIONS

The absence of actively suppressing FoxP3⁺ CD4⁺ T cells may in part explain why OLP is a remarkably persisting condition, in spite of the presence of substantially high numbers of FoxP3⁺ CD4⁺ T cells. The findings emphasize that it is crucial to examine not only numbers but also functional phenotype of FoxP3⁺ CD4⁺ T cells in human tissues.

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.

ALK1 expression in oral lichen planus: a possible relation to microvessel density

OBJECTIVE

To assess the expression of activin receptor-like kinase 1 (ALK1) and investigate its possible relationship with microvessel density (MVD) in different forms of oral lichen planus (OLP) compared to controls' biopsies.

METHODS

Biopsies from 20 reticular/papular OLP (R/PLP), 20 atrophic/erosive OLP (A/ELP) patients, and 20 healthy subjects were immunohistochemically analyzed and statistically compared and correlated for ALK1 expression and MVD as assessed by CD34 expression.

RESULTS

All OLP specimens revealed the presence of positive cytoplasmic CD34 immunostaining in endothelial cells, with statistically high significant MVD in each of R/PLP (Median; M = 4.40) and A/ELP (M = 7.69) compared to controls (M = 1.16) (P < 0.001). Statistically significant MVD was found in A/ELP compared to R/PLP (P < 0.001). All control specimens revealed negative ALK1 immunostaining of the few inflammatory cells found, while 85% of A/ELP cases and 70% of R/PLP cases showed positively immunostained sections for ALK-1, with statistically significant higher ALK1 expression In A/ELP (M = 1.95) compared to R/PLP (M = 0.86) (P = 0.005). No significant correlation between CD34 and ALK1 was detected in R/PLP (r = 0.081), while a barely moderate positive correlation was found in A/ELP (r = 0.396).

CONCLUSIONS

ALK1 expression and MVD are increased in OLP, particularly in A/ELP type.

Oral lichenoid lesion: A review of the literature

The oral lichenoid lesion (OLL) is response that occurs on the oral mucosa. The OLL include allergic response to the dental materials, drugs, and on graft-vs-host disease (GVHD). OLL to dental material happen when restorative materials, most commonly amalgam, are in direct contact with the mucosa in sensitized individuals. Medications that produce OLL are oral hypoglycemic agents, angiotensin-converting enzyme inhibitors, and nonsteroidal anti-inflammatory agents. GVHD is a complication in bone marrow transplantation and OLL is a common lesion observed in this disease especially in chronic GVHD. The clinical and histological aspects of OLL are similar to oral lichen planus and turn it difficult to make a differential diagnosis. The purpose of this paper is review about OLL related to the dental materials, drug use and GVHD.

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.

A comparative study of apoptosis in reticular and erosive oral lichen planus

The oral lichen planus (OLP) is a chronic inflammatory disease, probably autoimmune, with different clinical forms. The most common types are the reticular and the erosive ones. Apoptosis participates in the destruction of basal keratinocytes, but its role in the perpetuation of the subepithelial lymphocytic infiltrates was not yet investigated. To evaluate the involvement of apoptosis in the epithelium and in subepithelial lymphocytic infiltrates, 15 samples of reticular and erosive OLP and 10 samples of healthy oral mucosa were collected and processed histologically. Apoptosis was quantified in the epithelium and in inflammatory cell infiltrates. TUNEL reaction was used to measure apoptosis in the infiltrates. Erosive OLP showed more intense epithelial apoptosis than reticular OLP and controls. In contrast, apoptosis in the inflammatory cell infiltrates was more frequent in reticular than in erosive OLP. Lymphocytes were the predominant cells within the inflammatory cell infiltrates and were more frequent in erosive OLP than in reticular type. These results suggest that different apoptotic levels are involved in the erosive/reticular switch in OLP, determining different clinical presentations. In conclusion, decreased apoptosis in inflammatory infiltrates may contribute to the persistence of T lymphocytes, worsening the attack to the epithelium in erosive 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.

FoxP3(+) T regulatory cells in oral lichen planus and its correlation with the distinct clinical appearance of the lesions

The aim of this study was to evaluate the presence of FoxP3(+) cells in oral lichen planus (OLP) and to correlate the findings with clinical and histopathological features of these lesions. The sample consisted of 32 cases of OLP (17 reticular and 15 erosive cases) and 10 cases of inflammatory fibrous hyperplasia (IFH). Clinical examination, histopathological and histomorphometric analysis, and immunohistochemistry (anti-FoxP3 antibody) were performed. Cells were counted in juxtaepithelial and intraepithelial regions of the lesions, and the results are expressed as the mean and range. Most erosive lesions were keratinized and exhibited epithelial atrophy, whereas most reticular lesions were hyperkeratinized. Mean epithelial thickness and mean density of the inflammatory infiltrate were higher in reticular lesions than in erosive OLP. Juxtaepithelial FoxP3(+) cells were slightly more frequent in erosive lesions (mean: 1.7 and range: 0-9.4) than in reticular lesions (mean: 1.5 and range: 0-8.3). There was a significant difference in the frequency of these cells between OLP (mean: 1.6 and range: 0-9.4) and IFH (mean: 0.5 and range: 0-1.4) (P < 0.05). The number of intraepithelial FoxP3(+) cells was higher in reticular OLP and IFH when compared with erosive lesions. The larger number of juxtaepithelial FoxP3(+) cells in OLP compared to IFH might be related to the distinct etiopathogenesis of these lesions. High disease activity or action of the oral microbiota may explain the slightly higher frequency of FoxP3(+) cells in erosive lesions.

Expression of matrix metalloproteinase 9 in patients with oral lichen planus

INTRODUCTION

Oral Lichen planus (OLP) is chronic inflammatory oral mucosal disease of unknown etiology. Basement membrane damage and T-cell migration in OLP may be mediated by matrix metalloproteinases (MMPs). We examined the expression of matrix metalloproteinase 9 to support this hypothesis.

MATERIALS AND METHODS

The study population consisted of 71 patients with OLP and 10 control patients with oral fibromas. Indirect immunohistochemistry was used for detection of MMP 9 expression (polyclonal rabbit anti-human MMP antibody).

RESULTS

In all cases of OLP, the MMP-9 expression was seen mainly in the area oflymphocytic inflammatory infiltrate in the lamina propria including lymphocytes within the overlying epithelium. In addition, it was observed in the epithelial keratinocytes, particularly in the stratum basale and stratum spinosum with occasional positivity in the superficial layer. Fibroblasts and endothelium of small vessels in the lamina propria showed MMP9 expression as well. In all cases of oral mucosal fibromas, the MMP-9 expression was seen only in fibroblasts and in endothelium of small vessels with occasional positivity within the overlying epithelium. It remains unclear, whether MMP-9 is directly connected to OLP pathogenesis.

Analysis of Plasma Fibronectin Levels in Patients Affected by Oral Lichen Planus

Previous studies have demonstrated that patients affected by Oral Lichen Plauns (OLP) show lower levels of salivary fibronectin when compared with normal controls. Similarly, tissutal fibronectin expression is lost in epidermal basal layer and papillary dermis of OLP patients. To date, no data exist on the potential role of Plasma Fibronectin(PFn) in OLP pathogenesis, diagnosis and treatment. The objectives of the present study are: a) to determine the PFn levels in OLP patients; b) to evaluate a possible association between OLP clinical form and PFn levels; and c) to determine the PFn levels in relation to OLP signs and symptoms treatment. Twenty consecutive patients affected by OLP were enrolled. All patients were treated for eight weeks with topical clobetasol 0.05%. OLP signs and symptoms were scored before and after treatment. PFn level was determined by a nephelometric system. OLP signs and symptoms significantly improved after treatment. The mean levels of PFn were 31.84mg/dL at the beginning and 26.76mg/dL at the end of the study. The difference was not statistically significant (p=0.60). PFn in OLP patients remains in normal value range. OLP clinical form does not influence the PFn levels. Amelioration of symptoms and signs of atrophic-erosive and reticular OLP are induced by clobetasol treatment and the PFn seems not to interfere in the healing processes induced by topical corticosteroid. In contrast to what is observed in traumatic or diabetic wound healing, levels of PFn do not promote OLP lesion healing. PFn is not to be considered as a marker of OLP disease activity and its role in OLP pathogenesis still remains unclear.

Increased expression of Smad proteins, and in particular Smad3, in oral lichen planus compared to normal oral mucosa

BACKGROUND

Oral lichen planus (OLP) is a chronic inflammatory disease of the oral mucosa which the World Health Organisation (WHO) considers a premalignant condition. One step in malignant development is so called epithelial mesenchymal transition (EMT), a process whereby epithelial cells acquire mesenchymal characteristics. EMT occurs during embryogenesis and wound healing but also in some human diseases such as cancer and fibrosis. A factor known to induce EMT is transforming growth factor-β (TGF-β), which uses the Smad proteins as mediators for its signalling. TGF-β is also often over-expressed in squamous cell carcinoma of the head and neck (SCCHN).

METHODS

In the present study we mapped expression of Smad proteins in OLP lesions by immunohistochemistry, and compared to expression in normal and sensitive oral mucosa. The latter group of patients had developed SCCHN after shorter or longer periods of diffuse oral symptoms. The aim was to see if there were any signs of EMT related changes in the OLP lesions, as judged by changes in the TGF-β pathway.

CONCLUSION

Changes in the TGF-β pathway related to EMT are seen in the very earliest stages of oral malignancy and become more severe as lesions progress.

Quantitative analysis of epithelial papillae in patients with oral lichen planus

BACKGROUND

The oral mucosa is relatively vulnerable to pathological processes, and is often affected by autoimmune and malignant diseases. The oral epithelium is normally non-homogeneous, and joins to the connective tissue through interlocking of its downward projections in the form of papillae.

OBJECTIVE

This study aims to conduct a histomorphometric study of the epithelial papillae in patients with oral lichen planus (OLP).

MATERIAL AND METHOD

This study was based on 100 cheek mucosa biopsies from patients with OLP (66 white reticular and 34 atrophic-erosive) (13 males and 87 females, with a mean age of 54.95 +/- 13.64 years). A histological and morphometric evaluation was made, based on imaging analysis with MIP software 4.5 for studying the papillary structure in the patients with OLP.

RESULTS

The mean epithelial thickness was 227.5 +/- 78.5 microm. The different papillary measures--BLS (distance from basal layer to epithelial surface), DPS (distance from dermal papilla top to epithelial surface), DPW (dermal papilla width), and DPD (interdermal papilla distance between two papillae)--yielded no statistically significant differences with respect to age, sex, smoking and clinical form. However, a significant correlation was observed in relation to papilla width and inflammatory infiltrate (P = 0.031).

CONCLUSIONS

The application of this imaging system is useful for measuring variations in epithelial papillary architecture.

Oral lichen planus: clinical and histopathological considerations

Oral lichen planus is one of the most common dermatological diseases presenting in the oral cavity; the prevalence in the general population is 1% to 2%. Although relatively frequent, oral lichen planus is the target of much controversy, especially in relation to its potential for malignancy.

AIM

This study aimed to make clinical and histopathological considerations regarding oral lichen planus to increase the level of knowledge about this condition among health professionals, underlining the importance of long-term follow-up of these patients.

CONCLUSION

The possibility of this lesion to turn malignant justifies the importance of long term follow up for patients with such disease.

Role of apoptosis in erosive and reticular oral lichen planus exhibiting variable epithelial thickness

Oral lichen planus (OLP) is a chronic inflammatory disease with different clinical types. Reticular and erosive forms are the most common. Although the cause of OLP remains speculative, many findings suggest auto-immune involvement, mediated by T lymphocytes against the basal keratinocytes. Inflammation, mechanical trauma or toxic agents can affect the epithelial homeostasia. Increased apoptosis may cause a decrease in epithelial thickness reflecting in the activity of the lesion. The objective of this study was to evaluate the occurrence of apoptosis and epithelial thickness in reticular and erosive forms of OLP. 15 samples of OLP each type (reticular and erosive) plus 10 of healthy mucosa were collected and processed. After morphometry, the apoptotic index and epitelial thickness were obtained. TUNEL and M30 CytoDEATH immunohistochemical assay were used to validate the morphologic criteria used. Apoptosis in the erosive OLP was significantly more intense than in the reticular type and both forms of OLP presented more apoptosis than the healthy oral mucosa. Healthy oral mucosa was thicker than both OLP forms and thicker in OLP reticular form than in the erosive one. The clinical differences between reticular and erosive forms of OLP are related to variations in epithelial thickness and in intensity of apoptosis.

Significance of liquefaction degeneration in oral lichen planus: a study of its relationship with apoptosis and cell cycle arrest markers

OBJECTIVE

To assess the utility of liquefaction degeneration as a marker of apoptosis in oral lichen planus (OLP).

METHODS

TdT-mediated dUTP-biotin nick-end labelling (TUNEL) assay and immunohistochemical methods were used to detect p21 proteins and the active form of caspase 3 in 32 tissue samples of oral mucosa with OLP and 20 samples of normal oral mucosa.

RESULTS

Liquefaction degeneration was moderate or intense in 27.5% (n=8) and slight in 72.4% (n=21) of OLP samples. There was low expression of apoptosis markers (TUNEL, active caspase 3 form), which was not significantly associated with liquefaction degeneration of the basal cell layer. Basal and suprabasal expression of p21 was significantly more frequent in samples with more intense liquefaction degeneration of basal cells (P<0.01).

CONCLUSIONS

Our results demonstrate that liquefaction degeneration, as a morphological expression of T lymphocyte attack, does not unequivocally indicate apoptosis. Attacked basal cells more frequently respond with cell-cycle arrest or senescence than with apoptosis.

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.

Oral lichen planus treated with 13-cis-retinoic acid (isotretinoin): effects on the apoptotic process

The aim of the present study is to verify the efficacy of isotretinoin in oral lichen planus (OLP). In a double-blind study, ten patients with biopsy-proven OLP were treated for 4 months with 0.1% isotretinoin gel and another ten patients with placebo. At the end of the first period of observation, the patients who had been given the placebo were given isotretinoin for a further 4 months. A complete response was defined as the disappearance of the lesions as assessed by inspection, whereas a partial response was defined as a 50% or more reduction in the size of the lesions. All patients treated with isotretinoin showed a significant improvement of the oral lesions, whereas in the patients who were given the placebo, the size of the lesions remained the same. The patients who were given isotretinoin after the placebo showed a reduction in lesions. In total, there were ten complete and ten partial responses. Lesions were analysed histologically and immunohistochemically with antibodies against bcl-2 and Ki-67. Ki-67 and bcl-2 have statistical significant increased values from before to after treatment, whereas apoptotic bodies decreased one. All these facts could have contributed to the partial or complete regression of OLP lesions. The increase in Ki-67 positive cells show that the epithelium requires for enhanced proliferation and healing. The present results revealed a disturbed cell death programme in OLP that could underline an abnormal epithelial differentiation. The results of this pilot study show that the topical use of isotretinoin is effective in treating OLP.

Survival signalling in keratinocytes of erythematous oral lichen planus

BACKGROUND

Keratinocytes in oral lichen (OL) planus have been shown to be exposed to potentially cell death-inducing factors such as tumour necrosis factor-alpha (TNF-alpha) and FasL, produced by the cells of the inflammatory infiltrate and by the keratinocytes themselves. Mostly, however, the lesions do not show ulceration, the clinical manifestation of substantial keratinocyte death. The aim of this study was to find support for the contention that there is activation of protecting anti-apoptotic mechanisms in keratinocytes in a form of chronic OL (erythematous OL; ERY OL), simultaneously with the pathological cell death signals.

METHODS

Biopsies from patients with normal oral mucosa (NOM) or with ERY OL were compared by immunohistological staining.

RESULTS

In ERY OL keratinocytes, both the pro-apoptotic FADD and the anti-apoptotic molecules p-IKK, NF-kappaB/p50, FLIP(L), cIAP-1 and cIAP-2 were strongly upregulated when compared with NOM. There were no significant differences in the staining patterns for active caspase-3 and caspase-8 with only few positive cells for both enzymes.

CONCLUSIONS

The presently observed marked increase in expression of anti-apoptotic molecules in ERY OL epithelium may counteract the pro-apoptotic assault and rescue the epithelium from rampant cell death and thereby clinical ulceration.

Matrix metalloproteinase gene expression in oral lichen planus: erosive vs. reticular forms

BACKGROUND

Oral lichen planus (OLP) is an autoimmune disease of unknown aetiology. The pathogenesis is characterized by apoptosis of basal keratinocytes, triggered by contact between CD8+ -activated lymphocytes and an unknown antigen expressed on the surface of the basal cells. Basement membrane (BM) degradation, which allows lymphocytes to migrate, involves proteolytic enzymes known as matrix metalloproteinases (MMPs).

OBJECTIVES

This study aimed to evaluate the expression of a series of MMPs in biopsies from OLP patients, to reveal correlations with different clinical forms of OLP.

METHODS

Twenty-six patients diagnosed with OLP (14 reticular and 12 erosive) were studied, together with seven healthy patients as negative controls.

RESULTS

Reverse transcriptase polymerase chain reaction (RT-PCR) showed that the overall levels of expression of MMP mRNAs were higher in erosive lichen planus (E-OLP) than in the reticular forms (R-OLP). Moreover, MMP-1 and MMP-3 may be principally associated with erosion development. The expression of specific tissue inhibitors of metalloproteinases (TIMPs) was also evaluated.

CONCLUSIONS

The different clinical appearances of OLP are associated with significant differences in MMP mRNA levels.

Cell cycle regulating mechanisms in oral lichen planus: Molecular bases in epithelium predisposed to malignant transformation

OBJECTIVE

Expression of p53, p21, ki-67, Bcl-2 and caspase-3 proteins in oral lichen planus (OLP) was studied to investigate cell cycle regulation mechanisms in this disease.

MATERIAL AND METHODS

Oral biopsies were obtained from 51 patients with OLP and 26 controls for immunohistochemical analysis (peroxidase antiperoxidase) to quantify expression of the proteins under study (-: 0%, +: <10%, ++: 10-25%, +++: 26-50%, ++++: >50% positive cells).

RESULTS

Basal expression of caspase-3 was negative in 22 cases (46.8%) and positive in <10% of basal cells in 22 cases (46.8%); caspase-3 expression in inflammatory infiltrate was negative in 22 cases (46.8%) and positive in <10% of lymphocytes in 20 cases (42.5%). Basal expression of Bcl-2 was negative in 35 cases (74.5%); Bcl-2 was expressed in inflammatory infiltrate in 34 cases (72.3%) and was positive in <25% of lymphocytes in 14 of these (29.7%). Basal expression of p53 and p21 was positive in 32 (67.9%) and 23 (48.8%) cases, respectively. Basal expression of ki-67 was positive in 45 cases (95.7%), of which 20 (42.5%) showed positivity in >25% of cells; ki-67 was expressed in inflammatory infiltrate in 23 cases (48.9%). Significant associations were found between basal expressions of p53 and ki-67 (p<0.001) and between Bcl-2 expression in infiltrate and basal expression of ki-67 (p<0.001). No association was observed between basal expressions of p53 and caspase-3 (p=0.08). Bcl-2 expression in infiltrate and basal expression of ki-67 were independently associated with presence of OLP.

CONCLUSIONS

Epithelial cells in OLP do not preferentially develop apoptosis but rather cycle arrest or an increased proliferation rate, which may create a suitable substrate for malignant transformation.

Assessment of local angiogenesis and vascular endothelial growth factor in the patients with atrophic-erosive and reticular oral lichen planus

OBJECTIVES

The objective of this study was to assess local angiogenesis and expression of VEGF in atrophic-erosive and reticular oral lichen planus (OLP).

STUDY DESIGN

Microvessel density (MVD) and VEGF level in 30 OLP subjects and 7 matched controls were detected by immunohistochemistry and ELISA.

RESULTS

MVD and VEGF levels in whole OLP group were significantly elevated (P = .033, P < .0001, respectively), and there was a positive correlation between MVD and VEGF (correlation coefficient = 0.84, P < .0001). MVD in atrophic-erosive OLP was significantly higher than that in controls (P = .001) and reticular OLP (P = .042), and the expression of VEGF in both subgroups was significantly higher (P < .0001, P = .008, respectively) compared to control group.

CONCLUSION

These results indicated that angiogenesis and VEGF expression were closely correlated to the different clinical forms of OLP lesions, which may give new insights into the mechanisms and treatment strategy of OLP.

Short-term clinical evaluation of intralesional triamcinolone acetonide injection for ulcerative oral lichen planus

BACKGROUND

Efforts are made in a continued searching for novel therapies for symptomatic oral lichen planus (OLP). This study aimed to evaluate the efficacy and safety of intralesional triamcinolone acetonide (TA) injection for ulcerative OLP.

METHODS

Forty-five patients with clinical and histologically confirmed ulcerative OLP on bilateral buccal mucosa, one for treatment and the other for control, were studied. All participants received 0.5 ml TA (40 mg/ml) on experimental sites. Visual analogue scale score and lesion areas were recorded at the time of injection and 1-week interval. After 2 weeks, if the treated ulceration reduced < 81% in size, a second injection was given.

RESULTS

The treated group gave rapid relief of signs and symptoms, while the control group showed minimal decrease. 38 (84.4%) patients demonstrated complete response in ulceration size. No complications were noted with TA injections.

CONCLUSIONS

Intralesional TA injection in ulcerative OLP is effective and safe in achieving lesion and pain regression.

Number V Oral lichen planus: clinical features and management

Oral lichen planus (OLP) is a relatively common chronic inflammatory disorder affecting stratified squamous epithelia. Whereas in the majority of instances, cutaneous lesions of lichen planus (LP) are self-limiting and cause itching, oral lesions in OLP are chronic, rarely undergo spontaneous remission, are potentially premalignant and are often a source of morbidity. Current data suggest that OLP is a T cell-mediated autoimmune disease in which auto-cytotoxic CD8+ T cells trigger apoptosis of oral epithelial cells. The characteristic clinical aspects of OLP may be sufficient to make a correct diagnosis if there are classic skin lesions present. An oral biopsy with histopathologic study is recommended to confirm the clinical diagnosis and mainly to exclude dysplasia and malignancy. The most commonly employed and useful agents for the treatment of lichen planus (LP) are topical corticosteroids but other newer agents are available.

Higher expressions of p53 and proliferating cell nuclear antigen (PCNA) in atrophic oral lichen planus and patients with areca quid chewing

OBJECTIVE

The aim of the study was to examine the expressions of p53 and proliferating cell nuclear antigen (PCNA) in oral lichen planus (OLP) in relation to its clinical behavior and the patients' oral habits.

STUDY DESIGN

Immunohistochemical study was carried out to investigate the expressions of p53 and PCNA in 56 OLP specimens. The results were correlated with the clinical behavior of the disease and the patients' oral habits. The expression rates were further compared with those of normal oral mucosa (NOM), epithelial hyperkeratosis (EH), epithelial dysplasia (ED), and squamous cell carcinoma (SCC).

RESULTS

The staining rate of p53 (28.6%) and PCNA labeling index (LI) (27.6 +/- 8.8%) in OLP were similar to those in EH ( P = .868, .074, respectively), but higher than those of NOM and lower than those of ED and SCC (all P < .05). In OLP, no significant correlations were found between p53 or PCNA expression and the patients' age, gender, lesion duration, location, size, number of site, presence of pain, presence of local irritant, and the habits of alcohol drinking and cigarette smoking (all P > .05). In addition, the mean PCNA LI of p53+ cases was close to that of p53- cases (P = .38). However, the staining rate of p53 in OLP was higher in areca quid (AQ) chewers compared to abstainers (P = .001), and the mean PCNA LI in atrophic cases was higher than that in hypertrophic cases (P = .029). Interestingly, the staining rate of p53 and mean PCNA LI were significantly increased in AQ chewers with atrophic OLP (100%, 36.7% +/- 9.0%, respectively), which were similar to those in ED and SCC (all P > .05).

CONCLUSIONS

Although this study could not confirm the precancerous nature of OLP by the relatively low p53 and PCNA expression, the results do suggest that atrophic form OLP and patients with AQ chewing habit may have a higher disease activity in view of higher expression rates of p53 and PCNA in the lesions.

Inhibition of the Transforming Growth Factor-β/Smad Signaling Pathway in the Epithelium of Oral Lichen

The basal cells in epithelium of the erythematous form of oral lichen display hyperproliferation compared with normal oral mucosa. In this study we examined whether this is associated with disrupted production, activation, or signal transduction of the epithelial growth inhibitor transforming growth factor (TGF) beta1. In situ immunostaining showed that most epithelial cells in normal oral mucosa had nuclear and cytoplasmic Smad4 and phosphorylated Smad2/3, but expressed little or no Smad7. Expression of latency-associated peptide TGF-beta1, latent TGF-beta binding protein 1, TGF-beta type I receptor, and TGF-beta type II receptor was readily seen, but only very little TGF-beta1 was activated. In erythematous oral lichen, basal and lower spinous epithelial layers showed staining for latency-associated peptide TGF-beta1, TGF-beta type I receptor, and TGF-beta type II receptor. A band with scanty staining for these molecules, but with marked staining for active TGF-beta1, was seen in the upper spinous and granular layers. Numbers of epithelial cell nuclei with Smad4 and phosphorylated Smad2/3 staining were significantly reduced in erythematous oral lichen compared with normal oral mucosa. Basal and suprabasal cell layers in erythematous oral lichen showed strong cytoplasmic Smad7 protein staining, but in spinous and granular layers Smad7 was localized to the cell membrane. In situ hybridization showed strong Smad7 mRNA expression in almost all basal keratinocytes in erythematous oral lichen; by contrast, no or occasionally very weak Smad7 mRNA expression was seen in these cells in normal oral mucosa. The observations indicate that inhibition of the TGF-beta/Smad pathway may account for the hyperproliferation of keratinocytes in erythematous oral lichen.

[Oral precancerous conditions--an overview]

Precancerous conditions are defined as a generalized state associated with a significantly increased risk of cancer. For the oral and perioral region, sideropenic dysphagia, oral lichen planus (OLP), oral submucous fibrosis (OSF), syphilis, discoid lupus erythematosus, xeroderma pigmentosum as well as epidermolysis bullosa play a role as precancerous conditions. The number of published cases of oral or perioral malignant transformation for some of these diseases is small. In addition, carcinomas of the tongue and the oral cavity associated with syphilis are of historical interest, although publications in the 1990s still reported positive serology of syphilis and carcinomas of the tongue. OLP is still controversially discussed as to its premalignant nature. Transformation rates have been reported between 0% and 5.6%. Recent prospective studies have revealed that possibly oral lichenoid reactions (OLR) are more likely to form the basis of malignant transformation as compared to the classic OLP. The differentiation between OLP and OLR is difficult both from clinical and histopathological aspects. The second most important precancerous condition is oral submucous fibrosis, which is caused by betel quid chewing. OSF is most prevalent in South and Southeast Asia. The transformation rate is as high as 7.6% making OSF one of the most important precancerous conditions of the oral region.