Inflammatory cells of immunosuppressive phenotypes in oral lichen planus have a proinflammatory pattern of expression and are associated with clinical parameters

Salivary metabolomics in patients with oral lichen planus: a preliminary study based on NMR spectroscopy

OBJECTIVES

The present preliminary study aimed to investigate the salivary metabolic profile in patients with asymptomatic oral lichen planus (OLP) using nuclear magnetic resonance (NMR) spectroscopy.

MATERIAL AND METHODS

Stimulated whole mouth saliva (SWMS) samples were collected from 15 reticular OLP female patients and 15 from age- and sex-matched controls (HCs). A total of 23 metabolites were identified and quantified. Mann-Whitney's U test was used to compare the determined concentration salivary metabolite concentrations between OLP patients and the healthy controls.

RESULTS

The concentration of acetate, methylamine, and pyruvate was elevated, whereas the concentration of tyrosine was decreased in the saliva of OLP patients compared with HCs. To identify a combination of metabolites, multivariate discrimination function analysis (DFA) was conducted. DFA analysis have shown that the most powerful discrimination between the groups was achieved when methylamine and tyrosine were considered as combined biomarkers.

CONCLUSIONS

Salivary tyrosine was of particular interest and a promising finding for the screening of OLP and its progression. Further longitudinal studies are required to establish it as a reliable salivary biomarker in OLP.

CLINICAL RELEVANCE

The salivary metabolic profiling can describe the pathologic characteristics of OLP on non-invasive saliva samples and NMR analysis. Salivary metabolites provide details to considered early detectors and to impact oral health of OLP patients.

The potential roles of Th17 cells in the pathogenesis of oral lichen planus

BACKGROUND

Oral lichen planus (OLP) is a T cell-mediated chronic autoimmune disease, whose pathogenesis and etiology are not entirely understood. OLP is characterized by subepithelial lymphocyte infiltration and elevated intra-epithelial lymphocytes. The majority of lamina propria lymphocytes are CD4⁺ T cells. CD4⁺ helper T (Th) cells play a crucial role in activating CD8⁺ cytotoxic T cells (CTLs) through interactions and cytokine production. Th1 and Th2 cells are well-accepted to be associated with OLP pathogenesis. However, OLP treatment is challenging yet, the more information we have about the pathology of OLP, the easier it will be treated. With the discovery of Th17 cells in recent years and the demonstration of their role in autoimmune disease, many researchers started to investigate the role of Th17 in the pathogenesis of OLP.

METHODS

To make up this review, studies covering the role of TH17 in different types of lichen planus were selected from major databases.

RESULTS

As we review in this article, Th17 cells and their signature cytokines play an important role in OLP pathogenesis. As well, utilizing some anti-IL-17 antibodies showed promising results in improving the disease; however, more studies are still needed to better understand and treat OLP.

Lymphocyte and CD62E expression in lichen planus and lichenoid reaction

Background

It is difficult to distinguish the clinical and histopathological aspects of oral lichen planus lesions from those of oral lichenoid reaction. Some criteria were proposed to distinguish them, mainly because they have different biological behaviors. The aim of the present study was to compare the lymphocyte population and the expression of E-selectin between these lesions.

Methods

Participants with a clinical diagnosis of oral lichen planus (GOLP) and oral lichenoid reaction (GOLR) who needed to perform a biopsy were selected. The tissue was frozen and immunostaining was performed for CD3/CD4, CD3/CD8, CD4/CLA, CD8/CLA, and CD62E. The analysis of each immunostaining was accomplished using the ImageJ program.

Results

In total, 25 participants with oral lichen planus and 11 with oral lichenoid reaction were seen. In the evaluation of CD3 + CD4+/CD3 + and CD3 + CD8+/CD3 + proportions, there was a higher percentage of these cells in the oral lichen planus group when compared with the oral lichenoid reaction group (p = 0.027 and p = 0.038 respectively). The average number of CLA + lymphocytes for CD4+/CLA + and CD8+/CLA + in both groups was not statistically significant (p = 0.840; d = 0.363). In GOLP, the number of CD4 + CLA+/E-selectin and CD8 + CLA+/E-selectin was not statistically significant (p = 0.951 and p = 0.454 respectively); neither in GOLR (p = 0.454 and p = 0.989 respectively).

Conclusion

Our results indicate that CD3 + CD4+, CD3 + CD8+, CD4 + CLA+, CD8 + CLA + lymphocytes and E-selectin are present in both lesions. However, the proportion of CD3 + CD4+/CD3 + and CD3 + CD8/CD3 + cells is higher in the oral lichen planus group when compared with the oral lichenoid reaction group, suggesting that these cells may be important for the etiopathogenic mechanism of these lesions.

Does oral lichen planus aggravate the state of periodontal disease? A systematic review and meta-analysis

BACKGROUND

The objective of this systematic review and meta-analysis (SRM) was to assess the evidence between the association of oral lichen planus and periodontal disease, evaluating the periodontal clinical parameters and biomarkers levels.

METHODS

This systematic review and meta-analysis followed PRISMA and was registered in PROSPERO (CRD42020181513). Searches were accomplished in databases for articles published until June 2021. The meta-analysis was performed with the variables: plaque index (PI), gingival index (GI), probing depth (PD), and clinical attachment loss (CAL). The mean difference was applied with a 95% confidence interval.

RESULTS

Six articles were included. Qualitative analysis showed the levels of biomarkers (matrix metalloproteinases, interleukins, and periodontal microbiological profile) are increased in subjects with periodontal disease and oral lichen planus. In the meta-analysis, these subjects also presented increases in all periodontal clinical parameters evaluated: GI-gingivitis 0.22 [0.14, 0.31] p < 0.0001 and periodontitis 0.12 [0.06, 0.19] p = 0.0003; PI-gingivitis 0.22 [0.12, 0.31] p < 0.0001 and periodontitis 0.15 [0.08, 0.23] p < 0.0001; PD-gingivitis 0.27 [0.06; 0.48] p = 0.0107 and periodontitis 0.11 [0.01; 0.21] p = 0.0299; and CA-periodontitis 0.06 [0.01, 0.12] p = 0.0176.

CONCLUSIONS

Evidence suggests a significant relationship between the severity of periodontal disease and the presence of oral lichen planus. Although the association is biologically plausible, further studies are needed using populations and well-defined biochemical and clinical outcomes with consideration of potential confounding factors.

CLINICAL RELEVANCE

This SRM provides information on the interaction between OLP and periodontal disease and guides clinicians to make evidence-based decisions and suggests recommendations for further high-quality studies.

The presence of Prevotella melaninogenica within tissue and preliminary study on its role in the pathogenesis of oral lichen planus

OBJECTIVE

Oral lichen planus (OLP) is a chronic inflammatory disease that occurs in the oral mucosa with characteristic white striations lesions, recurrent erosions, and pains. The etiology and pathogenesis of OLP are still unclear.

MATERIALS AND METHODS

We analyzed the bacterial community structure of buccal mucosa in patients with OLP and normal controls by high-throughput sequencing. Fluorescence in situ hybridization (FISH) was used to detect Prevotella melaninogenica (P. melaninogenica) in 13 OLP samples and 10 controls. The amounts of P. melaninogenica in OLP buccal mucosa and the expression of inflammatory cytokines in co-culture of mouse-derived macrophages with P. melaninogenica were detected by RT-qPCR.

RESULTS

The P. melaninogenica was more abundant in OLP than in healthy controls, and the differences were significant at the level of the phylum, family, genus, and species (p < .05). FISH showed that P. melaninogenica can invade the epithelium and even the lamina propria of OLP, while no invasion was found in the normal mucosa. Prevotella melaninogenica can adhere to and invade macrophages and then activate the transcription of IL-1β, IL-6, and TNF-α in NF-κB signaling pathway.

CONCLUSION

Prevotella melaninogenica may be involved in the pathogenic process of OLP, and its specific mechanism deserves further study.

The role of CD68+ and CD163+ macrophages in immunopathogenesis of oral lichen planus and oral lichenoid lesions

Macrophages are phagocytic cells with essential participation in immunological events of the oral cavity. However, the role of these cells in oral lichen planus (OLP) and oral lichenoid lesions (OLL) remains unclear. The present study aimed to evaluate the density of macrophages in OLP and OLL, and to compare it with that of oral inflammatory fibrous hyperplasia (OIFH) (control group). 14 cases of OLP, 14 cases of OLL and 14 cases of OIFH were selected for immunohistochemical analysis of CD68⁺ (M1) and CD163⁺ (M2) macrophage expression. CD68⁺ and CD163⁺ macrophages densities were measured in the intraepithelial and subepithelial areas. The statistical tests used were multivariate analysis of variance, as well as a correlation and linear regression. OLP has more CD68+ macrophages when comparing with OLL (p = 0.001) and OIFH (p = 0.045). There is a very strong relationship between the macrophages types (p < 0.0001) in OLP and OLL. The linear regression showed that to OLL development (p < 0.0001/R^2' = 0.9584), the presence of different types of macrophages are more essential than to OLP (p < 0.0001/R^2' = 0.8983). However, in the OLP these dependencies are also largely. CD68⁺ macrophages may be associated with immunopathogenesis of OLP, indicating a pro-inflammatory activity and regulatory role in the type of T-cell response. Besides, CD68⁺ macrophages can cooperate in the diagnosis of OLP. These results are essential to future studies that seek a therapeutic target for OLP and OLL.

Comparative Evaluation of Mitochondrial Antioxidants in Oral Potentially Malignant Disorders

Various endogenous mitochondria-associated antioxidants protect mitochondria from oxidative stresses such as Superoxide Dismutase 2 (SOD2), Catalase, Glutaredoxin 2 (GLRX2), educed Glutathione (GSH), Glutathione Peroxidase (GPx), and Thioredoxin 2 (TXN2). They protect mitochondria from Reactive Oxygen Species (ROS). Excess ROS causes mitochondrial DNA damage and respiratory chain dysfunction leading to carcinogenesis. In an earlier study we found complex alterations of mitochondrial antioxidants in different stages of oral squamous cell carcinoma. Here, we profiled mitochondrial antioxidants in different oral potentially malignant disorders such as oral leukoplakia (OL), oral lichen planus (OLP), and oral submucous fibrosis (OSMF). Mitochondria was prepared from oral tissues from OL, OLP, and OSMF patients. Biochemical assays and immunoblotting were performed to investigate expression of various mitochondrial antioxidants. Catalase was expressed as Control> OL > OSMF > OLP. GLRX 2 was expressed as OLP> OL >Control >OSMF. GPX1 and GPX4 were expressed as Control >OSMF> OLP > OL. GSH increased in OL and OSMP, but decreased in OLP. SOD2 was expressed as Control >OSMF> OLP > OL. PRX3 was expressed as OL > OLP > OSMF > Control. TXN2 expression was nearly the same in all groups except OL, which showed elevated expression. We conclude that endogenous mitochondria-associated antioxidants show different levels of expressions in various oral potentially malignant disorders.

Chronic atrophic gastritis aggravate chronic periodontitis with Helicobacter pylori infection and CD4+Th cytokines infiltration

OBJECTIVE

To investigate the potential effect of chronic atrophic gastritis on chronic periodontitis and further explore the possible mechanism.

METHODS

Local periodontal lesions were collected from periodontitis tissues of 30 CAG patients and 35 control adults without CAG (non-CAG). Clinical periodontal parameters were recorded, and the expression levels of distinct CD4+ Th specific cytokines at local periodontitis lesions were evaluated by real time PCR (RT-PCR). Helicobacter pylori (H. pylori) detection was carried out in both gastric and periodontitis lesions of CAG and non CAG patients.

RESULTS

Clinical parameters analysis showed that the level of clinical attachment loss in periodontitis lesions of CAG group was significantly higher than non-CAG group. It was observed that the infection rate of H. pylori in the CAG group was higher than non-CAG group. Further cytokine analysis showed that Th17 associated cytokines IL-17, IL-21 and IL-23 were increased in periodontal lesions of CAG patients when compared with non-CAG patients. However, Th1, Th2, Th9 and Treg cells specific cytokines were not significantly increased in CAG group when compared with non-CAG group.

CONCLUSIONS

Patients with CAG demonstrated that significant elevated attachment loss in periodontitis lesions, while elevated Th17 cytokines IL-17, IL-21 and IL-23 participate in immunopathogenesis of both diseases.

Oxidative Stress and Oral Mucosal Diseases: An Overview

BACKGROUND

Reactive oxygen species (ROS) and free radicals are physiologically produced during cellular metabolism. When their balance is disrupted in favor of ROS, a condition called oxidative stress occurs. Oxidative stress represents a widespread phenomenon involved in several pathological conditions. The aim of the present review was to report current knowledge on oxidative stress related to oral mucosal diseases.

MATERIALS AND METHODS

Articles from 2000 to 2018 were selected for relevance, validity and quality, from results obtained in PubMed, MEDLINE and Google Scholar using the following search terms: oxidative stress and oral lichen, oral pemphigus, aphthous stomatitis, oral leukoplakia, oral cancer, oral squamous cell carcinoma and oral carcinoma. All articles were independently screened for eligibility by the authors.

RESULTS

This narrative review integrates extensive information from all relevant published studies focusing on oxidative stress in oral mucosal diseases. We outline the pathogenetic function of oxidative stress in the most frequent inflammatory, potentially malignant and malignant diseases of the oral mucosa and provide detailed findings from human research.

CONCLUSION

Although variability in findings between individual studies exists, it justifies the conclusion that oxidative stress is a significant process in the oral mucosal diseases pathogenesis.

Oral lichen-planus-associated fibroblasts acquire myofibroblast characteristics and secrete pro-inflammatory cytokines in response to Porphyromonas gingivalis lipopolysaccharide stimulation

Background

Oral lichen planus (OLP) is a chronic inflammatory oral mucosal disease in which comprehensive inflammation-related cytokines are involved. These cytokines are commonly produced by immune cells and specific nonimmune cells including keratinocytes, endothelial cells and fibroblasts. This raises the question of whether fibroblasts in OLP lesions contribute to the inflammatory process upon inflammatory simulation.

Methods

Primary cultured Oral lichen-planus-associated fibroblasts (OLP AFs, n = 5) and normal buccal mucosal fibroblasts (NFs, n = 5) were examined by immunohistochemistry, Western blotting and reverse transcription-polymerase chain reactions (RT-PCR). Various inflammatory mediators were evaluated with a multiplex assay. Differences among groups were assessed using a Student’s test or repeated measures one-way ANOVA, as appropriate.

Results

OLP AFs express significantly higher levels of α-smooth muscle actin (α-SMA) than NFs, indicating the presence of myofibroblasts. Myofibroblasts secrete Interleukin (IL)-6, IL-8, and tumor necrosis factor-α (TNF-α) in response to Porphyromonas gingivalis lipopolysaccharide (pg. LPS).

Conclusion

OLP AFs demonstrated α-SMA expression and secreted pro-inflammatory cytokines in response to pg. LPS stimulation.

Electronic supplementary material

The online version of this article (10.1186/s12903-018-0656-6) contains supplementary material, which is available to authorized users.

Evaluating the role of tissue microRNA-27b as a diagnostic marker for oral lichen planus and possible correlation with CD8

BACKGROUND

MicroRNA-27b (miR27b) is a small, non-coding RNA that is involved in physiological keratinocyte differentiation and regulating inflammatory processes. We performed this study to investigate the value of miR27b as a diagnostic marker for oral lichen planus (OLP) and the correlation between CD8 (cytotoxic T-cell marker) and miR27b tissue expression in OLP patients.

METHODS

Forty participants (including 20 OLP patients and 20 controls) underwent oral biopsy. The obtained specimens were examined by immunostaining and quantitative RT-PCR for CD8 and miR27b tissue expression, respectively. We used the Spearman rank correlation test to evaluate the correlation between both variables.

RESULTS

Our analysis showed that in comparison with healthy tissues, OLP tissue samples exhibited significantly higher CD8 levels (P < 0.01), as well as a significant downregulation of miR27b expression (P < 0.0001). Upon comparing different OLP subgroups, no significant difference was detected in terms of miR27b expression; however, the tissue levels of CD8 varied significantly (highest in the erosive subgroup and lowest in the papular/plaque/reticular subgroup). The Spearman rank analysis showed a negative correlation between tissue expression of miR27b and CD8; however, this was not statistically significant (P > 0.05). Further, the receiver operating characteristic curve of tissue miR27b as an OLP biomarker revealed 100% sensitivity and 65% specificity at cutoff value of 4.4.

CONCLUSION

This study demonstrated increased CD8 levels and downregulation of miR27b in OLP tissues, compared to healthy tissues. Moreover, it revealed the potential of miR27b as an OLP disease biomarker. The possible negative correlation between CD8 and miR27b tissue expression requires further investigation in larger studies.

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.

Immunoexpression of Th17-related cytokines in oral lichen planus

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

Etiology and pathogenesis of oral lichen planus: an overview

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

CLA and CD62E expression in oral lichen planus lesions

OBJECTIVE

There are few reports on the migration of CLA+ T cells through E-selectin in cutaneous lichen planus, with only one study on oral lichen planus (OLP). This study aimed to analyze CLA expression and assess whether there is a correlation with E-selectin (CD62E) in OLP lesions.

MATERIAL AND METHODS

Biopsies were performed on 11 patients including two areas: one without clinical and histopathological features of OLP [perilesional group (PLG)] and the other with clinical and histopathological features of OLP [OLP group (OLPG)]. The specimens obtained were divided into two: One was fixed in formalin for routine analysis (H&E), and the other was frozen for CD3, CD4, CD8, CLA, and CD62E immunofluorescence markers.

RESULTS

More CD4+ (median 1409, range 860-2519), CD8+ (median 1568, range 654-3258), and CLA+ T cells (median 958, range 453-2198) and higher CD62E expression (median 37, range 27-85) were identified in OLPG (P = 0.003; P = 0.003; P = 0.004; P = 0.003, respectively) than those in PLG. The median prevalence analysis was also significantly higher for CLA+CD8+ T cells in OLPG (OLPG = 39.4%, range 18.4-64.2; PLG = 29.4%, range 12.1-47.1) (P = 0.026). None of the correlations between CD3+ or CLA+ T cells and CD62E in OLPG and in PLG were significant.

CONCLUSION

The significant presence of CLA+ T cells and E-selectin expressions in the OLPG suggests their involvement in the etiopathogenesis of OLP; however, only a weak correlation between CLA+ T cells and E-selectin was observed.

Myeloid derived suppressor cells in physiological and pathological conditions: the good, the bad, and the ugly

Myeloid derived suppressor cells (MDSCs), a heterogeneous population of myeloid progenitors, are recognized as a key element in tumor escape and progression. The importance of MDSCs in human malignancies has been demonstrated in recent years, and new approaches targeting their suppressive/tolerogenic action are currently being tested in both preclinical model and clinical trials. However, emerging evidence suggests that MDSCs may play a prominent role as regulator of the physiologic, the chronic, and the pathologic immune responses. This review will focus on the biology of MDSC in light of these new findings and the possible role of this myeloid population not only in the progression of the tumor but also in its initiation.

Inflammation-related cytokines in oral lichen planus: an overview

Cytokines are powerful mediators which play a central role in both innate and adapted immune responses. Aberrant productions of cytokines may lead to the onset of immune deficiency, allergy or autoimmunity, which are involved in the mechanisms of various immune-mediated inflammatory diseases. Oral lichen planus (OLP) is a chronic inflammation disease affecting the oral mucosa with unknown aetiology. Previous studies have described the abnormal expression patterns of various inflammation-related cytokines, such as IL-1, 2, 4, 5, 6, 8, 10, 12, 17, 18, TGF-β, IFN-γ and TNF-α, in lesions, saliva, serum and peripheral blood mononuclear cells from patients with OLP, which may reflect the immune dysregulation status and emerge as central players in the immunopathogenesis of OLP. Besides, the gene polymorphisms of several cytokines such as IFN-γ, TNF-α, IL-4, IL-10 have been found to be involved in the susceptibility of OLP. In this review, we gave a brief introduction of the characteristics and biological functions of these inflammation-related cytokines and summarized for the first time the current knowledge on the involvement of inflammation-related cytokines in OLP. Further research on the exact roles of these cytokines will aid the understanding of the pathogenesis and the identification of novel therapeutic approaches of OLP.

Oral lichen planus may enhance the expression of Th17-associated cytokines in local lesions of chronic periodontitis

OBJECTIVES

This study aims to compare the expression levels of interleukin (IL)-17 and IL-23 in local periodontal tissues from patients with both chronic periodontitis and oral lichen planus (CP-OLP), patients with chronic periodontitis (CP) only, patients with oral lichen planus (OLP) only, and healthy controls (HC).

MATERIALS AND METHODS

The periodontal tissues were collected from 15 CP-OLP patients, 15 CP patients, 15 OLP patients, and 10 healthy controls. Immunohistochemistry (IHC) and real-time quantitative PCR (qPCR) was performed to investigate the protein and mRNA expression level of IL-17 and IL-23 in periodontal lesions from these four groups.

RESULTS

IHC statistical analysis showed that the expression level of IL-17- and IL-23p19-positive cells significantly increased in CP-OLP group compared with that in CP (P < 0.01) and OLP groups (P < 0.05), showing intense staining reaction in local lamina propria lesions. Meanwhile, qPCR result showed higher IL-17 mRNA level in CP-OLP compared with that in CP and OLP groups and demonstrated a significant increase than OLP group (P < 0.05). Moreover, it was found that IL-17 mRNA expression level in erosive CP-OLP patients was significantly correlated with probing depth and attachment loss (P < 0.05).

CONCLUSIONS

This study indicated that there was an increased expression level of IL-17 and IL-23 in periodontal tissues from periodontitis patients with oral lichen planus, which might aggravate the inflammatory response in local lesions.

CLINICAL RELEVANCE

Oral lichen planus and chronic periodontitis may have interaction in disease pathogenesis, while IL-17 detection in local lesions may be helpful in identifying the disease severity in periodontitis patients with oral lichen planus.

Transient liver hypoxia after liver hilus dearterialization

Lichen planus (LP) is a chronic inflammatory disorder that most often affects middle-aged adults. LP can involve the skin or mucous membranes including the oral, vulvovaginal, esophageal, laryngeal, and conjunctival mucosa. It has different variants based on the morphology of the lesions and the site of involvement. The literature suggests that certain presentations of the disease such as esophageal or ophthalmological involvement are underdiagnosed. The burden of the disease is higher in some variants including hypertrophic LP and erosive oral LP, which may have a more chronic pattern. LP can significantly affect the quality of life of patients as well. Drugs or contact allergens can cause lichenoid reactions as the main differential diagnosis of LP. LP is a T-cell mediated immunologic disease but the responsible antigen remains unidentified. In this paper, we review the history, epidemiology, and clinical subtypes of LP. We also review the histopathologic aspects of the disease, differential diagnoses, immunopathogenesis, and the clinical and genetic correlations.