Assessment of PD-1 and PD-L1 tissue expression levels in lichen planus patients: a case-control study.

Programmed cell death protein-1 (PD-1) is an immune checkpoint protein, PD-1 interaction with PD ligand-1 (PD-L1) is essential for maintaining immunological tolerance. The study aimed to study and compare the levels of PD-1 and PD-L1 in lesional and nonlesional skin of lichen planus (LP) patients and compare these levels to normal healthy controls to assess their role in the pathogenesis of LP. This case-control study involved 30 patients with LP and 30 healthy age-and sex-matched controls. After clinical assessment of the severity by LP severity index score (LPSI), skin biopsies were taken from lesional and nonlesional skin of LP patients and from normal skin in healthy controls for assessment of the tissue levels of PD-1 and PD-L1 by ELISA. The tissue levels of both PD-1 and PD-L1 were significantly higher in healthy controls than in both lesional and nonlesional skin of LP patients (P < 0.001). Also, significantly higher PD-l and PD-L1 levels in nonlesional skin than in lesional skin of LP patients were reported (P < 0.001). No significant correlations were found between lesional and nonlesional PD-1, PD-L1 levels, or LPSI score. Based on the fact that PD-1/PD-L1 interaction is important to maintain tolerance and protection against autoimmune diseases, in addition to our study results that revealed lower levels of PD-1/PD-L1 in LP skin than in healthy skin, we can conclude that PD-1/PDL-1 may be incriminated in the pathogenesis of LP. ClinicalTrials.govID: NCT04892381.

YAP1 Expression in Lichen Planus and Squamous Cell Carcinoma: Role in Disease Pathogenesis and Potential Therapeutic Target.

BACKGROUND: Lichen planus (LP), especially oral type, reported a potential risk of malignant transformation to squamous cell carcinoma (SCC). Yes-Associated Protein (YAP1), a key component of the Hippo pathway, acts as a transcription cofactor regulating expression of genes involved in cell proliferation, apoptosis, and migration. Therefore, it has been implicated in carcinogenesis of a wide variety of human cancers. OBJECTIVES: To study YAP1 expression in LP and SCC in comparison to normal control (NC) specimens. PATIENTS AND METHODS: This study was conducted on 50 NC specimens, 50 LP specimens, and 50 SCC specimens. They were categorized into 2 main groups; cutaneous (25 NC, 25 LP, 25 SCC), and oral (25 NC, 25 LP, 25 SCC). All specimens were examined for YAP1 antibody expression by immunohistochemistry and YAP1 mRNA expression by reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: In both cutaneous and oral groups; significant upregulation of YAP1 expressions was observed in SCC specimens followed by LP and then NC specimens in the same sequence. Its expression in SCC was found to be significantly higher in poorly and moderately differentiated types than well differentiated types. CONCLUSION: YAP1 may have a potential role in the pathogenesis of LP and oncogenesis and progression of SCC. Moreover, it could be considered as a novel therapeutic target for such cases.

Evaluation of correlation between transcription factors and IL-17 in oral and cutaneous lichen planus lesions and Leukocytes.

BACKGROUND: Lichen planus (LP) is a chronic autoimmune disease with different clinical subtypes including cutaneous LP (CLP) and oral LP (OLP). We aimed to compare mRNA expression of RORγt and IL-17 in paraffin-embedded blocks of OLP and CLP lesions with normal oral mucosa (NOM), and also its correlation with hematologic parameters. MATERIALS & METHODS: This study included 89 paraffin-embedded blocks contain OLP (44 cases), CLP (45 cases) and NOM from the archive of Mashhad University of Medical Sciences, Mashhad, Iran. The expression of RORγt and IL-17 was evaluated by Real-time RT-PCR method. The result was compared to Leukocyte counts and the other hematological parameters of studied patients. RESULTS: The results of our study showed IL-17 and RORγt expression in OLP lesions were significantly higher than CLP and NOM groups (P = 0.001). Although we found high expression of RORγt and IL-17 in erosive OLP in compared to classic OLP lesion, but this increment was not significant for IL-17 (P = 0.26) and RORγt (P = 0.14). Further, Leukocyte and monocyte counts were substantially high in OLP group in compared to the CLP and NOM groups (P < 0.05). CONCLUSIONS: We concluded that increased expression of RORγt and IL-17 in LP lesions could play role in the pathogenesis of LP. As well, higher expression of RORγt and IL-17 in oral LP more than cutaneous LP might be associated with difference in clinical behavior of the two types of disease and role of these factors in premalignant behavior of OLP lesions.

The role of autophagy-related gene 9B in lichen planus.

BACKGROUND: Lichen planus (LP) is an idiopathic, chronic, relapsing, inflammatory, autoimmune dermatological disease. The etiopathogenesis of LP is still unclear. Autophagy is a strictly regulated lysosomal degradation pathway that is crucial for maintaining intracellular homeostasis and normal development. The dysregulation of autophagy-associated genes was recognized to increase the susceptibility to multiple diseases, including inflammation, autoimmune disorders and cancer. AIMS: Our study aimed to detect the expression of autophagy-related gene 9 b (ATG9B) in LP patients compared to normal control persons to investigate the possible role of autophagy in pathogenesis of this disease. METHODS: This case-control study included 30 LP patients and 30 age-, gender-matched healthy controls. Four millimeters punch skin biopsies were obtained from LP lesions and from the controls and they were kept in lysis solution for the stability of the studied parameters and were kept frozen at -80°C till analysis of ATG9B using real-time polymerase chain reaction. RESULTS: The level of ATG9B in lesional skin of LP was significantly decreased compared to normal control persons (P < 0.01); also, there was a non-significant relation between ATG9B level and age, sex, duration and family history among LP patients. LIMITATIONS: Limited number of patients included in our study (30 patients). CONCLUSION: Autophagy may play a role in the pathogenesis of cutaneous LP.

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.

IL-17-positive mast cell infiltration in the lesional skin of lichen planopilaris: Possible role of mast cells in inducing inflammation and dermal fibrosis in cicatricial alopecia.

Lichen planopilaris (LPP) is a primary cicatricial alopecia characterized by the infiltration of lymphocytes in the upper portion of hair follicles. Inflammation around the bulge region of hair follicles induces destruction of hair follicle stem cells and tissue fibrosis, resulting in permanent hair loss. Treatment is still challenging, and the precise pathophysiology of this disorder is unknown. To clarify the pathogenesis of LPP, we performed histological and immunohistochemical analysis on specimens obtained from LPP patients. Formalin-fixed and paraffin-embedded samples were evaluated by staining with haematoxylin and eosin (HE), toluidine blue stain, immunohistochemistry and immunofluorescence. The immunohistochemical analysis demonstrated that CD4-positive T cells preferentially infiltrated into the follicular infundibulum in the LPP lesions. Toluidine blue stain detected a large number of mast cells in the inflammatory lesions of LPP. Interestingly, immunohistochemical analysis demonstrated that the mast cells harboured IL-17A- and IL-23-producing activity and expressed the IL-23 receptor. The number of IL-17A-positive mast cells was significantly higher in the LPP lesions than in normal scalp. Moreover, the IL-17 receptor was expressed exclusively in the follicular epithelial cells in the LPP lesions. These results suggested that mast cells infiltrating hair follicles might play a role in the pathogenesis of LPP via the IL-23/IL-17 axis.

"Normal-appearing" scalp areas are also affected in lichen planopilaris and frontal fibrosing alopecia: An observational histopathologic study of 40 patients.

Lichen planopilaris (LPP) and frontal fibrosing alopecia (FFA) are lymphocyte-mediated scarring alopecias which clinically affect primarily the anterior and mid-scalp. However, unaffected scalp areas have not yet been investigated in a systemic manner. In this study, we assessed histopathologic changes in affected and unaffected scalp in both diseases and healthy control subjects and compared these findings with clinical signs and scalp symptoms. We have demonstrated that "normal-appearing" scalp that is devoid of clinical lesions of LPP and FFA showed lymphocytic perifollicular inflammation around the isthmus/infundibulum areas in 65% of biopsy specimens, perifollicular fibrosis in 15% and mucin deposits in 7.5% of the cases. None of these findings were found in control samples. No direct correlation was found between the degree of histopathological inflammation, scalp symptoms and clinical lesions in the corresponding affected scalp areas. This preliminary study suggests that both diseases may be more generalized processes which affect the scalp and therefore need systemic or total scalp therapy.

A proposed mechanism for central centrifugal cicatricial alopecia.

Central centrifugal cicatricial alopecia (CCCA) has an unknown mechanism. Analyzing other scarring diseases (lichen planopilaris, fibrotic kidney disease and scleroderma) may help to clarify the mechanism of scarring in CCCA. These diseases were chosen for comparison due to either their location of disease (skin or scalp specifically), or prominence in patients of African descent. Genetics, possible triggers, an autoimmune lymphocytic response, and epithelial to mesenchymal transition are potentially involved. Possible common pathways in scarring diseases and a better understanding of the CCCA mechanism will lead to further research into the pathogenesis and potential treatments of CCCA.

PPAR-γ signalling as a key mediator of human hair follicle physiology and pathology.

Peroxisome proliferator-activated receptors (PPARs) are abundantly expressed in human skin, with PPAR-γ being the most intensively investigated isoform. In various ex vivo and in vivo models, PPAR-γ-mediated signalling has recently surfaced as an essential element of hair follicle (HF) development, growth and stem cell biology. Moreover, the availability of novel, topically applicable PPAR-γ modulators with a favourable toxicological profile has extended the range of potential applications in clinical dermatology. In this review, we synthesize where this field currently stands and sketch promising future research avenues, focussing on the role of PPAR-γ-mediated signalling in the biology and pathology of human scalp HFs, with special emphasis on scarring alopecias such as lichen planopilaris and frontal fibrosing alopecia as model human epithelial stem cell diseases. In particular, we discuss whether and how pharmacological modulation of PPAR-γ signalling may be employed for the management of hair growth disorders, for example, in scarring alopecia (by reducing HF inflammation as well as by promoting the survival and suppressing pathological epithelial-mesenchymal transition of keratin 15 + epithelial stem cells in the bulge) and in hirsutism/hypertrichosis (by promoting catagen development). Moreover, we explore the potential role of PPAR-γ in androgenetic alopecia, HF energy metabolism and HF ageing, and consider clinical perspectives that emanate from the limited data available on this so far. As this field of translational human hair research is still in its infancy, many open questions exist, for which we briefly delineate selected experimental approaches that promise to generate instructive answers in the near future.

Possible treatment for cutaneous lichen planus: An in vitro anti-inflammatory role of Angelica polysaccharide in human keratinocytes HaCaT.

Cutaneous lichen planus (CLP) is an autoimmune disease. Angelica polysaccharide (AP) has been found to exert immunomodulation activity. In this study, we explored the roles of AP in lipopolysaccharide (LPS)-induced inflammatory injury of human keratinocytes (HaCaT cells), as well as the underlying mechanisms. LPS-induced cell injury was evaluated by alterations of cell viability, apoptosis, and expressions of proteins associated with apoptosis and inflammatory cytokines. Then, the protective effects of AP on LPS-induced cell injury were assessed. The protein expressions of sirtuin 1 (SIRT1) and key kinases in the Nrf2/HO-1 and nuclear factor κB (NF-κB) pathways were measured using western blotting. SIRT1 knockdown and overexpression were used to analyze whether AP affected HaCaT cells through regulating SIRT1. Finally, the possible inhibitory effects of AP on cell injury after LPS treatment were also evaluated. We found that LPS reduced HaCaT cell viability, enhanced apoptosis, and induced release of inflammatory cytokines. AP alleviated LPS-induced HaCaT cell inflammatory injury. The expression of SIRT1 was enhanced after AP treatment. AP activated Nrf2/HO-1 pathway while inhibited NF-κB pathway in HaCaT cells. The protective effects of AP on LPS-induced HaCaT cell injury were reversed by SIRT1 knockdown. Dysregulation of SIRT1 altered the activation of Nrf2/HO-1 and NF-κB pathways in LPS-treated HaCaT cells. Furthermore, AP also exerted inhibitory effects on HaCaT cell injury after LPS stimulation. In conclusion, AP could alleviate LPS-induced inflammatory injury of HaCaT cells through upregulating SIRT1 expression and then activating Nrf2/HO-1 pathway but inactivating NF-κB pathway. This study provided a possible therapeutic strategy for clinical CLP treatments.

Dynamic thiol/disulfide homeostasis in patients with lichen planus.

OBJECTIVE: Lichen planus (LP) is an autoimmune inflammatory disease of the mucocutaneous tissue, whose exact pathological course remains unclear. Abnormal thiol/disulfide homeostasis has been postulated to be responsible for a number of diseases predominated by chronic inflammation. To be able to contribute complicated and unclear pathogenesis of LP, we aimed to investigate dynamic thiol/disulfide homeostasis in patients with LP, using an original automated method developed by Erel and Neselioglu in this study. METHODS: The study group consisted of 81 unrelated patients with LP and 80 unrelated healthy controls with no LP lesions in their personal history or on clinical examination. Thiol/disulphide homeostasis tests have been measured with a novel automatic spectrophotometric method developed and the results have been compared statistically. RESULTS: Native thiol and total thiol levels were found as significantly higher in patients with LP than the control group (P = 0.026 and 0.035, respectively). There was no significant difference between the disulfide levels of the patients with LP and the control group. CONCLUSIONS: We provide evidence that that thiol/disulphide homeostasis impaired in favor of thiol levels in LP patients compared to the control group based on the data of our study. To the best of our knowledge, the present study is the first examination on the correlation between thiol and disulfide homeostasis in patients with LP.

Lichen planus: altered AIM2 and NLRP1 expression in skin lesions and defective activation in peripheral blood mononuclear cells.

BACKGROUND: Lichen planus (LP) is an inflammatory skin disease with unknown aetiology. Activation by pathogen-associated molecular patterns or environmental stimuli may activate some components of inflammasomes that contribute to the inflammatory process in LP lesions. AIM: To characterize the inflammasomes in skin lesions and peripheral blood mononuclear cells (PBMCs) of patients with LP under Toll-like receptor (TLR) activation. METHODS: In total, 15 patients with LP and 14 healthy controls (HCs) were enrolled in the study. Inflammasome expression in skin was evaluated by real-time PCR and immunohistochemistry, while ELISA was used to assess the production of interleukin (IL)-1ß by PBMCs under stimulation with TLR4 and TLR7/TLR8 agonists and adenosine triphosphate (ATP). RESULTS: Compared with the levels in HC samples, increased expression of the inflammasome AIM2 was verified in both epidermal and dermal sections of LP skin lesions, whereas NLRP1 and IL-ß expression levels were enhanced in the dermis. LP skin lesion samples exhibited higher AIM2 transcript levels, similar NLRP1 levels and lower pro-IL-1ß mRNA levels compared with HC samples. We verified that, compared with PBMCs from HC subjects, PBMCs from patients with LP produced similar amounts of IL-1ß after induction by TLR4 agonists but lower IL-1ß levels after induction by TLR7/TLR8 agonists, regardless of the addition of ATP. CONCLUSION: Alterations in innate immunity, such as inflammasome component expression in skin lesions and PBMCs, were observed in patients with LP. Further investigations of dysfunctional inflammasome activation and the chronic inflammatory status of LP are required.

Differential expression of mTOR signaling pathway proteins in lichen planopilaris and frontal fibrosing alopecia.

Dysregulation of the mammalian target of rapamycin (mTOR) signaling pathway has a variety of effects on the immune system and stem cell proliferation. Lichen planopilaris (LPP) and frontal fibrosing alopecia (FFA) are inflammatory scalp conditions resulting in permanent alopecia, which are thought to be related to stem cell damage. Here we investigate the expression of mTOR signaling pathway proteins in human hair follicles of LPP and FFA patients. The expression of mTOR pathway proteins in biopsy specimens from lesional and non-lesional scalp areas of eight LPP and five FFA patients were compared to control scalp biopsies from patients undergoing surgical excisions of sebaceous cysts. We performed immunohistochemical evaluation using a panel of antibodies including mTOR, phospho-mTOR (Ser2448), phospho-p70S6K (Thr389), phospho-4EBP1 (Thr37146), and phospho-tuberin (T1462), as well as Western blot analysis for phospho-p70S6K (Thr389) expression. All evaluated mTOR pathway proteins were similarly expressed in the control and patient non-lesional scalps. While mTOR expression did not show significant alterations between the groups, p-mTOR, p-p70S6K, p-4EBP1, and p-tuberin expressions decreased in the interfollicular epidermis in the lesional scalps of patients. p-p70S6K and p-4EBP1 expression decreased in the outer root sheath (ORS) and inner root sheath (IRS) of the bulge of hair follicles in the lesional scalps of patients. p-mTOR and p-p70S6K expression increased in the lower follicle ORS and bulb of the hair follicles, and p-4EBP1 expression decreased in the bulb of the hair follicles in the lesional scalps of patients. Phospho-tuberin expression increased in the IRS of the bulge and lower follicle ORS of the hair follicles in the lesional scalps of patients, whereas its expression decreased in the bulb. Our results indicate that the mTOR signaling pathway proteins are localized throughout normal hair follicles and that expression of mTOR signaling pathway proteins is altered in the hair follicles of LPP and FFA patients. Further research is required to understand the mechanism by which mTOR operates in the pathogenesis of these diseases.

Increased expression of p16 in both oral and genital lichen planus

BACKGROUND: Lichen Planus, LP, is an inflammatory disease of possible autoimmune origin affecting mainly oral and genital mucosa and skin. According to the WHO oral LP is considered a potentially malignant disorders. The p16 tumour suppressor protein can act as an inhibitor of cyclin dependent kinases 4 and 6 and thus down regulate cell cycle progression. Since the discovery of p16 several studies have evaluated its expression in various forms of human cancers. The aim of this study was to evaluate and compare the expression of p16 in oral and genital LP and corresponding healthy mucosa. MATERIAL AND METHODS: A total of 76 cases of oral LP (OLP), 34 cases of genital LP (GLP), 12 cases of healthy oral and 9 cases of healthy genital mucosa were analysed by the use of immunohistochemistry. RESULTS: Data showed p16 to be highly expressed in both oral and genital LP, higher than in oral (p = 0.000), and genital controls (p = 0.002). CONCLUSIONS: Results suggest that the over-expression of p16 seen in LP play a part in the histopathology of the disease

Increased expression of p16 in both oral and genital lichen planus.

BACKGROUND: Lichen Planus, LP, is an inflammatory disease of possible autoimmune origin affecting mainly oral and genital mucosa and skin. According to the WHO oral LP is considered a potentially malignant disorders. The p16 tumour suppressor protein can act as an inhibitor of cyclin dependent kinases 4 and 6 and thus down regulate cell cycle progression. Since the discovery of p16 several studies have evaluated its expression in various forms of human cancers. The aim of this study was to evaluate and compare the expression of p16 in oral and genital LP and corresponding healthy mucosa. MATERIAL AND METHODS: A total of 76 cases of oral LP (OLP), 34 cases of genital LP (GLP), 12 cases of healthy oral and 9 cases of healthy genital mucosa were analysed by the use of immunohistochemistry. RESULTS: Data showed p16 to be highly expressed in both oral and genital LP, higher than in oral (p=0.000), and genital controls (p=0.002). CONCLUSIONS: Results suggest that the over-expression of p16 seen in LP play a part in the histopathology of the disease.

C-Jun expression in lichen planus, psoriasis, and cutaneous squamous cell carcinoma, an immunohistochemical study.

The AP-1 transcription factor complex is a key player in regulating inflammatory processes, cell proliferation, differentiation, and cell transformation. The aim of the present study is to investigate C-Jun (one of AP-1complex) expression and its proliferative role in skin samples of lichen planus, psoriasis as common inflammatory skin diseases and squamous cell carcinoma using immunohistochemical method. The present study was carried out on skin biopsies of 15 psoriatic patients, 15 lichen planus patients, 15 SCC, and 15 normal skin biopsies. Nuclear expression of C-Jun was detected in basal and few suprabasal layers of epidermis of normal skin. C-Jun was expressed in the whole epidermal layers of both psoriasis (14/15) and lichen planus (15/15) in addition to its expression in lymphocytic infiltrate in the latter in about half of cases (8/15). C-Jun was also expressed in 93.3% (14/15) of SCC in a percentage lower than that of psoriasis, lichen planus, and normal skin. The percentage of C-Jun expression in SCC was significantly associated with an early stage (p = 0.000), free surgical margins (p = 0.022), and small tumour size (p = 0.003). CONCLUSIONS: The marked reduction of C-Jun in SCC in comparison to normal skin and inflammatory skin dermatoses may refer to its tumour suppressor activity. C-Jun expression in SCC carries favourable prognosis. Absence of significant association between C-Jun and Ki-67 either in SCC or inflammatory skin diseases indicates that it does not affect proliferative capacity of cells.