Expression of Foxp3 and interleukin-17 in lichen planus lesions with emphasis on difference in oral and cutaneous variants

TYK2 inhibition with deucravacitinib ameliorates erosive oral lichen planus

Erosive oral lichen planus (OLP) is a challenging disease. This T cell driven disorder frequently shows a treatment unresponsive course and strongly limits patients' quality of life. The disease lacks FDA or EMA approved drugs for its treatment and the efficacy of the commonly administered treatments (i.e. topical and systemic steroids, steroid sparing agents) is often only partial. Although the etiopathogenesis of the disease still needs to be fully elucidated, recent advances helped to identify interferon-ɣ (IFN-ɣ) as a pivotal cytokine in OLP pathogenesis, thus making the interference with its signalling a therapeutic target. Janus kinase (JAK) inhibitors therefore gained relevance for their inhibitory effect on IFN-ɣ signalling. While some drugs such as abrocitinib, upadacitinib, tofacitinib directly interfere with IFN-ɣ signalling through blockade of JAK1 and/or JAK2, deucravacitinib, a selective TYK-2 inhibitor indirectly interferes on IFN-ɣ activation through interference with interleukin (IL)-12, a potent promotor for Th1/IFN-ɣ responses. This mechanism of action makes deucravacitinib a candidate drug for the treatment of OLP. Here we provide initial evidence that deucravacitinib 6 mg daily has a beneficial effect in three patients with oral OLP.

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.

Comprehensive Insight into Lichen Planus Immunopathogenesis

Lichen planus is a chronic disease affecting the skin, appendages, and mucous membranes. A cutaneous lichen planus is a rare disease occurring in less than 1% of the general population, while oral illness is up to five times more prevalent; still, both forms equally impair the patient's quality of life. The etiology of lichen planus is not entirely understood. Yet, immune-mediated mechanisms have been recognized since environmental factors such as hepatitis virus infection, mechanical trauma, psychological stress, or microbiome changes can trigger the disease in genetically susceptible individuals. According to current understanding, lichen planus immunopathogenesis is caused by cell-mediated cytotoxicity, particularly cytotoxic T lymphocytes, whose activity is further influenced by Th1 and IL-23/Th-17 axis. However, other immunocytes and inflammatory pathways complement these mechanisms. This paper presents a comprehensive insight into the actual knowledge about lichen planus, with the causal genetic and environmental factors being discussed, the immunopathogenesis described, and the principal effectors of its inflammatory circuits identified.

The Functional Mechanism of MicroRNA in Oral Lichen Planus

Non-coding RNAs (ncRNAs) are transcribed from the genomes of mammals and other complex organisms, and many of them are alternately spliced and processed into smaller products. Types of ncRNAs include microRNAs (miRNAs), circular RNAs, and long ncRNAs. miRNAs are about 21 nucleotides long and form a broad class of post-transcriptional regulators of gene expression that affect numerous developmental and physiological processes in eukaryotes. They usually act as negative regulators of mRNA expression through complementary binding sequences in the 3’-UTR of the target mRNA, leading to translation inhibition and target degradation. In recent years, the importance of ncRNA in oral lichen planus (OLP), particularly miRNA, has attracted extensive attention. However, the biological functions of miRNAs and their mechanisms in OLP are still unclear. In this review, we discuss the role and function of miRNAs in OLP, and we also describe their potential functional roles as biomarkers for the diagnosis of OLP. MiRNAs are promising new therapeutic targets, but more work is needed to understand their biological functions.

Salivary expression of lncRNA DQ786243 and IL-17 in oral lichen planus: case-control study

Background

A growing number of studies has investigated IL-17 in OLP. However, its exact role and interactions are not fully determined. In addition, the literature investigating its salivary expression is limited. The scarcity in the literature studying lncRNAs was noticed, particularly with regards to correlating them with cytokines in OLP. In the current study, the salivary expression of lncRNA DQ786243 and IL-17 was assessed among different forms of OLP.

Methods

The study included 52 participants in four equal groups: reticular OLP, erythematous OLP, ulcerative OLP, and control group. All eligible OLP patients underwent conventional oral examination, along with basic charting of their demographic data, pain intensity using a visual analogue scale, and clinical evaluation using the Thongprasom et al. scale. The salivary expression of lncRNA DQ786243 and IL-17 was evaluated for all participants using qRT-PCR. Unstimulated whole saliva samples were used. Data were analyzed for statistical significance.

Results

No statistically significant difference was observed when comparing the mean age and gender distribution of the studied groups. A statistically significant difference was detected when comparing pain and clinical scores in the three OLP forms. The highest expression of both salivary biomarkers was noticed in ulcerative OLP, followed by erythematous OLP and reticular OLP, then the controls, with a significant difference between the studied groups. Upon comparing the salivary expression of DQ786243 in ulcerative and erythematous OLP, no significant difference was detected. No significant difference was detected when comparing salivary expression of IL-17 in erythematous OLP to the other OLP forms.

Conclusions

The salivary expression of lncRNA DQ786243 and IL-17 was upregulated in OLP compared to healthy individuals. Besides, their expression increased when the severity of OLP was at its highest level in ulcerative OLP. There was a positive correlation between DQ786243 and IL-17.

Trial registration The protocol was registered at ClinicalTrials.gov (NCT04503824). The date of registration is 07/08/2020.

Probiotics as Potential Biological Immunomodulators in the Management of Oral Lichen Planus: What's New?

Oral lichen planus (OLP) is a T cell-mediated chronic inflammatory disorder with multifactorial aetiology and malignant transformation potential. Despite the treatments so far identified, new tailored and safe specific measures are needed. Recently, human microbiota imbalance has been linked to several immune-mediated diseases, opening new therapeutic perspectives for probiotics; besides their ability to directly interact with the host microbiota, they also display a strain-specific immune-modulatory effect. Thus, this non-systematic review aims to elucidate the molecular pathways underlying probiotic activity, mainly those of Lactobacilli and Bifidobacteria and their metabolites in OLP pathogenesis and malignant transformation, focusing on the most recent in vitro and in vivo research evidence. Findings related to their activity in other immune-mediated diseases are here included, suggesting a probiotic translational use in OLP. Probiotics show immune-modulatory and microbiota-balancing activities; they protect the host from pathogens, hamper an excessive effector T cell response, reduce nuclear factor-kappa B (NF-kB) signalling and basal keratinocytes abnormal apoptosis, shifting the mucosal response towards the production of anti-inflammatory cytokines, thus preventing uncontrolled damage. Therefore, probiotics could be a highly encouraging prevention and immunotherapeutic approach for a safer and more sustainable OLP management.

The role of interleukin-17 (IL-17) in the pathogenesis of discoid lupus erythematosus and lichen planopilaris: is immunohistochemistry for IL-17 a promising way to differentiate these entities?

BACKGROUND

Interleukin-17 (IL-17) is a pro-inflammatory mediator which its excess secretion by immune cells is found in many chronic autoimmune diseases. This survey is aimed to compare the amount and pattern of distribution of IL-17 positive cells in lichen planopilaris (LPP) and discoid lupus erythematosus (DLE) which are of the most frequent causes of primary cicatricial alopecia (CA).

METHODS

Biopsies of lesional scalp skin from adult LPP (n = 30), DLE patients (n = 19), and control scalp skin (n = 18) were analyzed by immunohistochemistry (IHC) method using rabbit polyclonal antibody against IL-17. Cells stained positive for IL-17 and their pattern of distribution were assessed and compared between these groups.

RESULTS

The mean of IL-17 positive cell counts per high power field (HPF) in both LPP and DLE groups was significantly higher in comparison with the control group (both p < .0001). The LPP group had higher values of IL-17 positive cell counts per HPF (47.56 ± 13.37) compared to the DLE group (22.21 ± 11.06) (p < .0001). More than 30 IL-17 positive cell counts in IHC have a sensitivity of 90% and a specificity of 78% for differentiating LPP from DLE.

CONCLUSIONS

Our findings suggest that IL-17 is effective in the pathogenesis of DLE and LPP and its role is more prominent in LPP. IL-17 positive cells in IHC can distinguish DLE from LPP with satisfactory sensitivity and specificity.

Lichen planus - a clinical guide

Lichen planus (LP) is a chronic lichenoid inflammatory disorder of the skin, mucosa and of the appendages. LP is classically characterized by the presence of a rich infiltration of inflammatory T cells, which migrate in the upper part of the dermis, arranged in a band-like pattern. Different sub types of the disease have been so far described. Albeit LP is clinically well defined, the disease still represents a therapeutic enigma. Especially with regard to mucosal or scalp affecting LP types, which often present a recalcitrant and treatment unresponsive course, efficacious therapeutic options are still lacking. Thus, LP represents a disease with a high psychosocial burden. Yet, development in the deciphering of LP pathogenesis reveals possible new druggable targets, thus paving the way for future therapeutic options. In this clinical guide, we summarize the current clinical knowledge and therapeutic standards and discuss the future perspective for the management of LP.

Immunohistochemical analysis of the expression of selected cell lineage markers (CD4, CD8, CD68, c-Kit, Foxp3, CD56, CD20) in cutaneous variant of lichen planus

BACKGROUND

Lichen planus (LP) is considered to be an immune-mediated disease of a not fully understood etiology. There are scarce data on the immune cells forming the band-like infiltration in cutaneous LP (CLP). The objective of the current study was to investigate the immunohistochemical pattern of cells forming the infiltrate in CLP by assessing the immunoexpression of selected cell lineage markers.

METHODS

The immunohistochemical analysis of the expression of CD4, CD8, CD20, CD56, CD68, c-Kit, and Foxp3 was performed in formalin-fixed paraffin-embedded (FFPE) biopsy specimens from 14 cases of CLP and 11 healthy volunteers.

RESULTS

The expression of CD4 (P < 0.001), CD8 (P < 0.001), CD68 (P < 0.001), Foxp3 (P < 0.001), CD56 (v = 0.019), and CD20 (P < 0.001) was significantly higher in lesional skin in CLP compared to healthy controls. The ratio of CD4+ to CD8+ cells in the infiltrate was 1.75:1. The expression of Foxp3, CD56, and CD20 was markedly lower than the expression of CD4 and CD8. There was no statistically significant difference in c-Kit expression between CLP lesions and healthy skin (P = 0.57).

CONCLUSIONS

We found a wide variety of immune cells in the inflammatory infiltrate in CLP. The expression of CD4, CD8, CD68, Foxp3, CD56, and CD20 was significantly increased in CLP, while the expression of c-Kit was comparable in lesional skin and controls. The presence of various cell populations, including T regulatory cells, NK cells, and B cells, may indicate a complex pathogenesis of CLP.

The possible involvement of granulysin mediated cytotoxicity in keratinocytes disruption in lichen planus

Lichen planus is a chronic mucocutanous disorder histopathologically characterized with a keratinocytes apoptosis, subsequent basal cell layer liquefaction and accumulation of the inflammatory infiltrate in papillary dermis. A formation of apoptotic bodies in basal cell layer is due to a cytotoxic lymphocyte attack to the basal keratinocytes. It has been demonstrated that the cytotoxic molecules included in this attack are perforin and granzyme B. Both molecules are found upregulated in CD8+ lymphocytes that are in close contact to keratinocytes. However, their amount is lower in lichen planus than in other skin disease characterized by liquefaction and vacuolar degeneration of the basal epidermal layer. This could speculate about other cytotoxic molecule such as granulysin that could mediate keratinocyte apoptosis. Therefore, in this article we hypothesize about the crucial role of granulysin molecule in keratinocytes killing that could contribute to a lichen planus pathogenesis.

The inflammation in cutaneous lichen planus is dominated by IFN-ϒ and IL-21-A basis for therapeutic JAK1 inhibition

Cutaneous lichen planus (CLP) and psoriasis (PSO) are both common chronic inflammatory skin diseases for which development of new treatments requires the identification of key targets. While PSO is a typical Th17/IL-17-disorder, there is some evidence that Th1/IFN-ɣ dominate the inflammatory process in CLP. Nonetheless, the immunopathogenesis of CLP is not fully explained and key immunological factors still have to be recognized. In this study, we compared the immune signature of CLP lesions with the well-characterized inflammation present in PSO skin. First, we analysed the histological and immunohistological characteristics of CLP and PSO. Second, we assessed the cytokine expression (IL1A, IL1B, IL4, IL6, IL8, IL10, IL17A, IL19, IL21, IL22, IL23A, IL13, IFNG, TNF, IL12A, IL12B and IL36G) of lesional skin of CLP with PSO by qPCR. Histology revealed a similar epidermal thickness in CLP and PSO. Immunohistochemically, both diseases presented with an inflammatory infiltrate mainly composed by CD3⁺ CD4⁺ T cells rather than CD3⁺ CD8⁺ . Importantly, mRNA analysis showed a distinct cytokine signature: while levels of IL12B, IL1A, IL6 and IL23 were similar between the two groups, the characteristic PSO-associated cytokines IL8, IL17A, IL22, IL19 and IL36G were expressed at very low levels in CLP. In contrast, CLP lesional skin was dominated by the expression of IFNG, IL21, IL4, IL12A and TNF. Immunohistochemistry confirmed the dominance of IL-21, IFN-ɣ and also pSTAT1 in the dermal infiltrate of CLP, while IL-17A was more present in PSO. Collectively, this study improves our understanding of the immunological factors dominating CLP. The dominating cytokines and signalling proteins identified suggest that anti-cytokine therapeutics like JAK inhibitors may be beneficial in CLP.

Possible Relation between Vitamin D and Interleukin-17 in the Pathogenesis of Lichen Planus

BACKGROUND

Lichen planus (LP) is a chronic autoimmune inflammatory mucocutaneous disease. Interleukin (IL)-17 is the signature cytokine of T-helper 17 cells, involved in the aetiology of many autoimmune and inflammatory disorders. Vitamin D has an immune-regulatory role and suppresses IL-17 production via direct transcriptional inhibition of IL-17 gene expression.

OBJECTIVE

To explore the relationship of IL-17 and vitamin D levels with LP, and the possible inter-relationship between IL-17 and vitamin D.

METHODS

The study enrolled 30 patients with LP and 30 healthy controls. Blood samples and skin biopsies were taken from all participants for evaluation of serum vitamin D, and serum and tissue IL-17 levels using enzyme-linked immunosorbent assay (ELISA).

RESULTS

Patients had significantly higher serum and tissue IL-17 (p < 0.001 for both), as well as significantly lower serum vitamin D levels and more deficient patterns of vitamin D status than controls (p < 0.001 for both). In the patient group, there was a statistically significant positive correlation between extent of the disease and serum IL-17. There was no direct statistical correlation between IL-17 levels and serum vitamin D in either patients or controls.

CONCLUSION

This study confirms a previously suggested role of IL-17 in the pathogenesis of LP and suggests its relation to the extent and severity of the disease. We also found an association between vitamin D deficiency and LP. However, a direct relationship between IL-17 and vitamin D deficiency could not be clarified.

Increased Serum Level and High Tissue Immunoexpression of Interleukin 17 in Cutaneous Lichen Planus: A Novel Therapeutic Target for Recalcitrant Cases?

Background

Interleukin-17 is supposed to play an important role in the pathogenesis of oral lichen planus (OLP). However, there is scarce data in the literature on its significance in the cutaneous variant of the disease.

Objectives

To determine the serum level and tissue immunoexpression of IL-17 in cutaneous lichen planus (CLP).

Methods

Fifty-two adult patients with CLP, without any significant autoimmune or inflammatory conditions, were included in the first part of the study. The control group consisted of 27 age- and sex-matched healthy volunteers. Serum concentration of IL-17 was quantified using enzyme-linked immunosorbent assay (ELISA) kit. In the second part of the study, the tissue expression of IL-17 was assessed in archival paraffin-embedded biopsy specimens from CLP (n = 14) against normal control tissues (n = 11) using immunohistochemical assays. The expression was evaluated using Zeiss Axio Imager A2 light microscope. Positively stained cells were counted in 10 fields of view for biopsy specimen at 200x magnification, and the mean value was calculated.

Results

The serum level of IL-17 was significantly elevated in patients with CLP, compared with healthy volunteers (0.218 ± 0.221 ng/ml versus 0.126 ± 0.058 ng/ml, respectively; p = 0.025). No correlation was found between the serum concentration of IL-17 and patient age, gender, disease duration, extent of skin involvement, the presence or intensity of pruritus, and coexistence of mucosal lesions. In tissue samples from CLP lesions, significantly higher numbers of cells expressing IL-17 were found when compared to a healthy skin (p < 0.001).

Conclusion

Elevated serum concentration of IL-17 and high expression in a lesional skin support the hypothesis that IL-17 is implicated in the immunopathogenesis of CLP. These findings may constitute a premise for the future use of anti-IL-17 monoclonal antibodies in the treatment of severe and recalcitrant forms of CLP.

Recalcitrant lichen planopilaris and frontal fibrosing alopecia responding to tildrakizumab

Lichen planopilaris (LPP) and frontal fibrosing alopecia (FFA) are lymphocytic, cicatricial alopecias. Clinically, LPP presents with multifocal patchy alopecia, while FFA, considered a variant of LPP, results in hairline recession. Frontal recession in FFA may progress as far as the mid-scalp and infrequently beyond. Treatment to arrest the inflammatory process can be challenging and response variable. We report a case of recalcitrant lichen planopilaris and frontal fibrosing alopecia demonstrating significant clinical improvement after four doses of the interleukin-23 monoclonal antibody tildrakizumab.

Photodynamic therapy in oral lichen planus: A prospective case-controlled pilot study

Oral lichen planus (OLP) is a common, chronic relapsing inflammatory disorder of the mucous membranes, which causes major discomfort. Current treatment includes topical/systemic glucocorticoids, immune modulators and systemic immunosuppressants, which may lead to considerable side-effects. The aim of this study was to determine the clinical and immunological efficacy of photodynamic therapy (PDT) in OLP as an alternative, easy-to-use, safe and non-invasive treatment. Twenty patients with OLP were treated with PDT in a prospective case-controlled pilot-study. PDT was performed on the most extensive oral lesion in 4 sessions (day 1, 3, 7, 14). Peripheral blood and lesional T cells were analysed before (day 1) and after PDT treatment (day 28). PDT led to a statistically significant reduction of clinical parameters (lesion size, ABSIS, Thongprasom-score) and improvement of all evaluated quality-of-life (QOL) items. The clinical improvement was accompanied by a significant decrease of the relative number of CD4+ and CD8+ T cells in mucosal OLP-lesions. Furthermore, CXCL10 plasma levels were decreased and the number of activated peripheral CD4 + CD137+ and CD8 + CD137+ T cells and IL-17-secreting T cells was diminished. PDT treatment in OLP leads to lesion reduction and improvement of QOL, and induces local and systemic anti-inflammatory effects. The study identifies PDT as a novel therapeutic option in OLP.

Cytokines Levels and Salivary Microbiome Play A Potential Role in Oral Lichen Planus Diagnosis

Oral lichen planus (OLP) is a chronic Th1-mediated inflammatory mucocutaneous disease of the skin and oral mucosa that can have various clinical presentations. Lesions are usually bilateral and often painful. While cutaneous Lichen Planus (LP) lesions are self-limiting, the oral lesions are chronic and rarely remissive. The diagnosis of oral lichen planus (OLP) is often challenging, and confirmation by histopathological criterion is generally advised. The aim of our study was to identify the cytokines present in OLP-suggestive lesions and in non-specific inflammatory lesions (NSIL) used as controls. Moreover, assess cytokines protein levels and oral microbiota composition in whole saliva samples. Histopathological analysis, immunohistochemistry and gene expression were used as techniques to analyze the oral mucosal tissue samples. ELISA was conducted to analyze salivary cytokine levels and 16S rRNA sequencing was used to determine the salivary microbiome. As a result we observed larger number of infiltrated lymphocytes (p = 0.025), as well, more T CD4 lymphocytes in the epithelial tissue (p = 0.006) in OLP samples compared to NSIL. In addition, the OLP samples displayed more apoptotic cells compared to NSIL (p = 0.047). Regarding the cytokine analysis, IFN-γ and IL-33 were more expressed in OLP lesions than in NSIL samples (p < 0.001; p = 0.026). Furthermore, our results demonstrated higher levels of IFN-γ protein expression in the saliva of OLP group compared to controls (p = 0.0156). We also observed noted differences in the oral microbiota composition between OLP and NSIL saliva samples. In conclusion, OLP lesions presented larger numbers of apoptotic and inflammatory cells, higher levels of IFN-γ and IL-33 compared to NSIL, and these lesions also differ regarding oral microbiota composition. These results are consistent with the Th-1-mediated chronic inflammation nature of oral lichen planus investigated lesions and displayed unique features that could be used as a diagnostic tool.

Significant reduction in the expression of interleukins-17A, 22 and 23A, forkhead box p3 and interferon gamma delineates lichen planus pigmentosus from lichen planus

Recent studies have noticed significant role of interleukin (IL)-17, 22, 23, Foxp3, interferon-gamma (IFN-γ) and Wnt5a in oral and cutaneous lichen planus (LP). This study was undertaken to assess whether similar expression exists in lichen planus pigmentosus (LPP). We recruited 30 patients of treatment-naïve 'LPP' (in absence of cutaneous/mucosal LP elsewhere, group 1), 10 patients having active treatment-naïve cutaneous 'LP' (group 2), 10 patients having 'post-LP' hyperpigmentation (in absence of active LP and off treatment for at least past 3 months, group 3), and 10 controls. Quantitative real-time polymerase chain reaction (qRT-PCR, peripheral blood mononuclear cells [PBMCs] and skin) and immunohistochemistry (IHC, skin) was performed. mRNA expression (in PBMCs) of IL-17A, IL-22, IL-23A, IFN-γ and Foxp3 was significantly decreased in group 1 and 3 as compared to group 2 (p < 0.05). Wnt5a expression was maximal in controls; and while there was no difference between group 1 and 2; whereas expression in group 3 was significantly lesser than group 1 and 2 (p < 0.05). qRT-PCR (skin) and IHC (skin) revealed similar results; and mRNA expression and mean fluorescence intensity of IL-17A, IL-22, IL-23A/R was significantly increased in group 2 and 3 compared to group 1 (p < 0.05). Mean fluorescence intensity and mRNA expression of IFN-γ, Foxp3 and Wnt5a were significantly increased in group 2 compared to group 1 (p < 0.05); whereas the difference between group 1 and 3 was not significant. Mean fluorescence intensity and mRNA expression of IL-17A, 1L-22 and IFN-γ showed no difference between group 2 and 3; whereas that of IL-23A/R, foxp3 and wnt5a were significantly higher in group 2 than group 3 (p < 0.05). Overall, maximal expression of IL-17A, IL-22, IL-23A, IFN-γ and Foxp3 (mRNA PBMCs) was observed in LP. Minimal expression of IL-17A, IL-22, IL-23A/R, IFN-γ and Foxp3 (mRNA skin and IHC skin) was seen in LPP patients. In contrast to LP, LPP lacks the expression of IFN-γ, Foxp3 and the cytokines representing Th17 pathway, and thus seems to have a distinct pathogenesis.

Frequently Increased but Functionally Impaired CD4+CD25+ Regulatory T Cells in Patients with Oral Lichen Planus

Oral lichen planus (OLP) is a T cell-mediated chronic inflammatory mucosal disease, and CD4(+)CD25(+) regulatory T cells (Tregs) are considered involved in the pathogenesis of OLP. In this study, to investigate whether there are intrinsic factors that might cause functional changes in Tregs in this disease, we evaluated the frequency of Tregs in peripheral blood and oral lesions and the expression levels of function-related transcription factors, forkhead/winged-helix transcription factor box P3 (FOXP3), transforming growth factor β (TGF-β), interleukin 10 (IL-10), and TGF-β receptors (TβRI and TβRII) mRNAs in Tregs of patients with oral lichen planus (OLP). We also investigated the frequency of pro-inflammatory cytokines (IFN-γ and IL-17A) producing Foxp3(+) regulatory cells. Increased proportions of Tregs were found in OLP patients. The expression of FOXP3 on mRNA and protein level was elevated in the Tregs of OLP. The expression of TGF-β was lower both on the mRNA and serum level, whereas the expression of IL-10 showed no significant difference between the OLP patients and normal controls. The percentages of CD4(+)FOXP3(+)IL-17(+) T cells were significantly higher than that of normal controls, whereas the percentages of CD4(+)FOXP3(+)IFN-γ(+) T cells did not differ significantly. Furthermore, impaired suppressive function of CD4(+)CD25(+) T cells was demonstrated in OLP patients by in vitro proliferation assay. These data indicate that Tregs in OLP are frequently expanded but functionally deficient. This could explain, at least in part, why the increased Tregs in OLP fail to control the pathogenesis and development of this autoimmune disease.

Clinical and Histopathologic Characterization of Canine Chronic Ulcerative Stomatitis

Canine chronic ulcerative stomatitis, also known as chronic ulcerative paradental stomatitis, is a painful condition of the oral cavity. The purpose of this study was to determine if there are commonalities in clinical and radiographic features among patients, whether the histopathologic evaluation might inform the pathogenesis, and whether the condition appears similar to human oral mucosal diseases. To do this, we prospectively collected clinical, radiographic, and histopathologic data from 20 dogs diagnosed with the disease. Clinical data were based on a clinical disease activity index, oral and periodontal examination parameters, and full-mouth dental radiographs. The histopathological and immunohistochemical data were based on oral mucosal samples obtained from erosive or ulcerated areas. Our findings revealed that canine chronic stomatitis is clinically characterized by painful oral mucosal ulcers of varying size, pattern, appearance, and distribution, most often associated with teeth with early periodontitis. Histologic examination revealed a subepithelial lichenoid band (interface mucositis) where B cells, T cells, and Forkhead-box protein 3 (FoxP3)- and interleukin-17-expressing cells were present. These cells might play a role in the underlying immune response and an immune-mediated pathogenesis is suspected. The clinical and histopathologic features of this chronic inflammatory mucosal disease in dogs resemble those of oral lichen planus in humans.

Altered expression of interleukin-17A and its targeting microRNAs in oral lichen planus: a pilot study

OBJECTIVE

To investigate the potential role of interleukin (IL)-17A and its targeting microRNAs (miRNAs) in oral lichen planus (OLP).

STUDY DESIGN

We compared the IL-17A expression levels in biopsies from patients with OLP (n = 50) against normal controls (n = 19) by using reverse transcription quantitative polymerase chain reaction (RT-qPCR) and Western blot analyses, identified the targeting miRNAs of IL-17A, and examined the miRNA expression levels in OLP.

RESULTS

IL-17A expression was significantly increased in patients with OLP compared with controls. The dual-luciferase reporter assay system demonstrated that miR-635 and miR-578 were the target miRNAs of IL-17A in human embryonic kidney 293 cells, which was consistent with predictions from bioinformatics software analyses. In contrast with IL-17A, the expression levels of miR-635 and miR-578 in OLP were significantly decreased compared with controls.

CONCLUSIONS

This pilot study found that low levels of miR-635 and miR-578 expression were associated with high expression of IL-17A, suggesting that IL-17A and its targeting miRNAs contribute to the pathogenesis of OLP.

Distinct interferon-gamma and interleukin-9 expression in cutaneous and oral lichen planus

BACKGROUND

Cutaneous (CLP) and oral lichen planus (OLP) as the main subtypes of lichen planus (LP) present with different clinical manifestation and disease course, although their histopathologic features such as the band-like lymphocyte infiltrate and keratinocyte apoptosis are similar. So far, the underlying cellular and molecular mechanisms remain poorly understood.

OBJECTIVE

The aim of this study was to characterize and compare the in situ cellular infiltrates, cytokine expression profiles and apoptosis markers in CLP and OLP.

METHODS

Using immunofluorescence staining and laser scanning microscopy, we evaluated the cellular infiltrate (CD1a, CD3, CD4, CD8, CD21, CD57, CD123), cytokine expression (interleukin (IL)-1, IL-6, IL-9, IL-10, IL-17, IL-22, IL-23, tumour necrosis factor-α, transforming growth factor-β, interferon (IFN)-γ), and apoptosis markers (Fas, Fas ligand, cleaved caspase-3, TUNEL) of 21 anonymized biopsy specimens of LP (11 CLP, 10 OLP).

RESULTS

Among infiltrating cells mainly T cells and natural killer (NK) cells as well as plasmacytoid dendritic cells (DC) were observed. A predominance of CD8+ T cells was noted in OLP. In both CLP and OLP, T helper (Th)1, Th9, Th17, and Th22-type cytokines were expressed. The expression of IL-9, IFN-γ and IL-22 was higher in CLP compared to that of OLP (P = 0.0165; P = 0.0016; P = 0.052 respectively). Expression of Fas and Fas ligand as well as cleaved caspase-3-positive cells was observed in the epithelium of all LP samples.

CONCLUSIONS

The cell and cytokine patterns of CLP and OLP were partially distinct and generally resembled those reported for autoimmune diseases. The presence of CD8+ and NK cells as well as Fas/Fas ligand expression suggested that various pathways involved in keratinocyte apoptosis are relevant for LP. These results might help to establish targeted therapies for LP.

The many faces of interleukin-17 in inflammatory skin diseases

Interleukin (IL)-17 is an emerging target for inflammatory skin disorders. Given the remarkable success of its therapeutic inhibition in psoriasis, the pathogenic role of this cytokine is being explored in other immune-mediated diseases. Interestingly, IL-17 is linked to particular skin conditions where its activation coincides with disease flares. The leading hypothesis for its contribution to proinflammatory signalling cascades is driving inflammasome activation. However, IL-17 stimulation also releases a range of noninflammasome-related cytokines from human skin. Furthermore, a role in cytotoxic responses and an important interplay with the microbiome is hypothesized. While treatment failure would be surprising in neutrophilic dermatoses, the picture might be more complex in lymphocyte-mediated conditions. Nonetheless, increasing insights into the pathogenesis suggest that beneficial responses are also probable in the latter conditions. Study of this pathway in the skin reveals some intriguing aspects of the IL-17-related immunological network.

Value of Foxp3 expressing T-regulatory cells in renal tissue in lupus nephritis; an immunohistochemical study

BACKGROUND

Forkhead box P3 (Foxp3) functions as a master regulator in the development and function of T-regulatory (Treg) cells. Recent studies have shown that autoimmune diseases including systemic lupus erythematosus (SLE) are associated with an imbalance with the Treg cells and T helper (Th) subtypes.

OBJECTIVES

To evaluate immunohistochemical expression of Foxp3 positive Treg cells in lupus nephritis (LN) and analyze its association with clinicopathologic parameters.

MATERIALS AND METHODS

Renal biopsy specimens of 50 patients with LN were studied. Specimens were divided into; group A; 25 LN cases without proliferative activity (Class II and V) and group B: 25 cases with proliferative activity (Class III and IV). Immunohistochemical staining for anti-human Foxp3 antibody and grading from grade 0 to grade 3 was done.

RESULTS

Foxp3 expression in group A was (grade 0 in 14 [56.0%], grade +1 in 11 [44.0 %]) in comparison to group B (grade +1 in 6 [24.0%], grade +2 in 11 [44.0%] and grade +3 in 8 [32.0%]) (P < 0.001). Foxp3 expression was significantly correlated to National Institutes of Health (NIH) activity and chronicity indices (P < 0.05), as well as serum creatinine (P < 0.01) in both groups A and B and there was a highly significant correlation with proteinuria (P < 0.01) in group B with proliferative LN.

CONCLUSIONS

Immunohistochemical Foxp3 expression in renal tissue was higher in proliferative versus non-proliferative LN and is associated with activity and severity of LN. Further studies are needed to determine its prognostic value in LN.

Activation of myeloid dendritic cells, effector cells and regulatory T cells in lichen planus

Background

Lichen planus (LP) is a chronic mucocutaneous inflammatory disease. Evaluating the balance between regulatory T cells and effector T cells could be useful for monitoring the proinflammatory profile of LP. Therefore, this study aimed to assess populations of dendritic cells (DCs) and regulatory and effector T cells in peripheral blood samples collected from patients with LP to evaluate the polyfunctionality of T cells upon toll-like receptor (TLR) activation.

Methods

Peripheral blood mononuclear cells collected from 18 patients with LP and 22 healthy control subjects were stimulated with agonists of TLR4, TLR7, TLR7/TLR8 or TLR9. Frequencies of circulating IFN-α⁺ plasmacytoid DCs (pDCs); TNF-α⁺ myeloid DCs (mDCs); regulatory T cells (Tregs); and IL-17-, IL-10-, IL-22-, TNF-, and IFN-γ-secreting T cells were assessed via flow cytometry.

Results

The frequencies of regulatory CD4⁺ and CD8⁺CD25⁺Foxp3⁺CD127^low/− T cells and TNF-α⁺ mDCs were induced following activation with TLR4, TLR7 and TLR8 agonists in the LP group. Moreover, increased baseline frequencies of CD4⁺IL-10⁺ T cells and CD8⁺IL-22⁺ or IFN-γ⁺T cells were found. In the LP group, TLR4 activation induced an increased frequency of CD4⁺IFN-γ⁺ T cells, while TLR7/8 and staphylococcal enterotoxin B (SEB) activation induced an increased frequency of CD8⁺ IL-22⁺ T cells. An increased frequency of polyfunctional CD4⁺ T cells that simultaneously secreted 3 of the evaluated cytokines (not including IL-10) was verified upon TLR7/8/9 activation, while polyfunctional CD8⁺ T cells were already detectable at baseline.

Conclusions

TLR-mediated activation of the innate immune response induced the production of proinflammatory mDCs, Tregs and polyfunctional T cells in patients with LP. Therefore, TLR activation has an adjuvant role in inducing both innate and adaptive immune responses.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-0938-1) contains supplementary material, which is available to authorized users.

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.

Oral lichen planus: an update on its pathogenesis

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

Wnt5a is involved in the pathogenesis of cutaneous lichen planus

BACKGROUND

Cutaneous lichen planus (CLP) is a chronic inflammatory and immune-mediated disease. Wnt5a is one of the most extensively studied Wnt proteins, and has important functions in stimulating inflammation, cell proliferation, cell fate determination and cell differentiation. Wnt5a expression in CLP has not been comprehensively studied to date.

AIM

To determine the expression and distribution of Wnt5a in CLP.

METHODS

Skin samples were obtained from patients with CLP and healthy controls (HCs). The WNT5A gene was detected by real-time quantitative PCR, and Wnt5a protein by immunohistochemical analysis and western blotting.

RESULTS

WNT5A mRNA was upregulated in CLP samples compared with the HC skin samples (P < 0.001). Wnt5a protein was overexpressed in all layers of the epidermis and dermis in CLP lesions compared with HC skin (all P < 0.001). These results were confirmed by western blotting.

CONCLUSIONS

The data presented in this study suggest that Wnt5a pathway may play an important role in the pathogenesis of CLP.