Role of Janus kinase 1 and signal transducer and activator of transcription 3 in vitiligo

Mechanisms of action of Lycium barbarum polysaccharide in protecting against vitiligo mice through modulation of the STAT3-Hsp70-CXCL9/CXCL10 pathway

CONTEXT

Vitiligo is a common skin disease with a complex pathogenesis, and so far, no effective treatment is available. Lycium barbarum L. (Solanaceae) polysaccharide (LBP), the main active ingredient of goji berries, has been demonstrated to protect keratinocytes and fibroblasts against oxidative stress.

OBJECTIVE

This study explored the effects and mechanism of LBP on monobenzone-induced vitiligo in mice.

MATERIALS AND METHODS

C57BL/6 mice were randomly divided into five groups (n = 6): negative control that received vaseline, vitiligo model group induced by monobenzone that treated with vaseline, positive control that received tacrolimus (TAC), LBP groups that received 0.3 and 0.6 g/kg LBP, respectively. We quantified the depigmentation by visual examination and scores, detected the expression of CD8+ T cells, pro-inflammatory cytokines and analysed the STAT3-Hsp70-CXCL9/CXCL10 pathway.

RESULTS

LBP 0.3 and 0.6 g/kg groups can significantly reduce depigmentation scores and the infiltration of local inflammatory cells in the skin lesions. Moreover, the expression of CXCL9, CXCL3, CXCL10 and HSP70 decreased by 54.3, 20.3, 48.5 and 27.2% in 0.3 g/kg LBP group, which decreased by 62.1, 26.6, 58.2 and 34.5% in 0.6 g/kg LBP group. In addition, 0.3 and 0.6 g/kg LBP decreased the release of IL-8 (9.7%, 22.8%), IL-6 (40.8%, 42.5%), TNF-α (25.7%, 35%), IFN-γ (25.1%, 27.6%) and IL-1β (23.7%, 33.7%) and inhibited the phosphorylation expression of STAT3 by 63.2 and 67.9%, respectively.

CONCLUSION

These findings indicated LBP might be recommended as a new approach for vitiligo which provide a theoretical basis for the clinical application of LBP in treating vitiligo patients.

Increased Expression of Long Noncoding RNA LOC100506314 in T cells from Patients with Nonsegmental Vitiligo and Its Contribution to Vitiligo Pathogenesis

This study aimed to identify the abnormal expression of long noncoding RNAs (lncRNAs) in T cells from patients with vitiligo and to investigate their functional roles in the immune system. Using microarray analysis, the expression levels of RNA transcripts in T cells from patients with vitiligo and controls were compared. We identified several genes and validated their expression levels in T cells from 41 vitiligo patients and 41 controls. The biological functions of the lncRNAs were studied in a transfection study using an RNA pull-down assay, followed by proteomic analysis and western blotting. The expression levels of 134 genes were significantly increased, and those of 142 genes were significantly decreased in T cells from vitiligo patients. After validation, six genes had increased expression, and three genes had decreased expression in T cells from patients with vitiligo. T-cell expression of LOC100506314 was increased in vitiligo, especially CD4+, but not CD8+ T cells. The expression levels of LOC100506314 in CD4+ T cells was positively and significantly associated with the severity of vitiligo. LOC100506314 was bound to the signal transducer and activator of transcription 3 (STAT3) and macrophage migration inhibitory factor (MIF). Enhanced expression of LOC100506314 inhibited the phosphorylation of STAT3, protein kinase B (AKT), and extracellular signal-regulated protein kinases (ERK), as well as the levels of nuclear protein of p65 and the expression of IL-6 and IL-17 in Jurkat cells and T cells from patients with vitiligo. In conclusion, this study showed that the expression of LOC100506314 was elevated in CD4+ T cells from patients with vitiligo and associated the severity of vitiligo. LOC100506314 interacted with STAT3 and MIF and inhibited IL-6 and IL-17 expression by suppressing the STAT3, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), AKT, and ERK pathways. Enhanced expression of LOC100506314 in T cells may be a potential treatment strategy for vitiligo.

Research Progress of Small Molecules as Anti-vitiligo Agents

Vitiligo is a disease characterized by skin discoloration, and no safe and effective drugs have been developed until now. New drug research and development are imminent. This article reviews the research on small-molecule drugs for vitiligo from 1990 to 2021 at home and abroad. They are classified according to their structures and mechanisms of action, including natural products and derivatives, anti-oxidative stress drugs, immunosuppressants, prostaglandins, etc. The research on their anti-vitiligo activity, structural modification, new dosage forms, clinical trials, and the development trend in new anti-vitiligo drugs are reviewed, which provides important references for the development of new drugs.

Role of Cytokines in Vitiligo: Pathogenesis and Possible Targets for Old and New Treatments

Vitiligo is a chronic autoimmune dermatosis of which the pathogenesis remains scarcely known. A wide variety of clinical studies have been proposed to investigate the immune mediators which have shown the most recurrency. However, such trials have produced controversial results. The aim of this review is to summarize the main factors involved in the pathogenesis of vitiligo, the latest findings regarding the cytokines involved and to evaluate the treatments based on the use of biological drugs in order to stop disease progression and achieve repigmentation. According to the results, the most recurrent studies dealt with inhibitors of IFN-gamma and TNF-alpha. It is possible that, given the great deal of cytokines involved in the lesion formation process of vitiligo, other biologics could be developed in the future to be used as adjuvants and/or to entirely replace the treatments that have proven to be unsatisfactory so far.

Identification of a Potentially Functional circRNA-miRNA-mRNA Regulatory Network in Melanocytes for Investigating Pathogenesis of Vitiligo

CircRNAs have been reported to play essential roles in regulating immunity and inflammation, which may be an important regulatory factor in the development of vitiligo. However, the expression profile of circRNAs and their potential biological functions in vitiligo have not been reported so far. In our study we found there are 64 dysregulated circRNAs and 14 dysregulated miRNAs in the patients with vitiligo. Through the correlation analysis, we obtained 12 dysregulated circRNAs and 5 dysregulated miRNAs, forming 48 relationships in the circRNA-miRNA-mRNA regulatory network. Gene Ontology analysis indicated dysregulated circRNAs in vitiligo is closely related to the disorder of the metabolic pathway. The KEGG pathway of dysregulation of circRNAs mainly enriched in the biological processes such as ubiquitin mediated proteolysis, endocytosis and RNA degradation, and in Jak-STAT signaling pathway. Therefore, we found the circRNA-miRNA-mRNA regulatory network are involved in the regulation of numerous melanocyte functions, and these dysregulated circRNAs may closely related to the melanocyte metabolism. Our study provides a theoretical basis for studying the vitiligo pathogenesis from the perspective of circRNA-miRNA-mRNA network.

MicroRNA‑21‑5p protects melanocytes via targeting STAT3 and modulating Treg/Teff balance to alleviate vitiligo

Vitiligo (VIT) is caused by loss and degradation of functional epidermal melanocytes. Studies have indicated that melanocyte destruction may be associated with an imbalance between regulatory T cells (Treg cells) and effector T cells (Teff cells). The current study aimed to investigate the molecular mechanism through which Treg/Teff balance affects VIT pathogenesis. To explore this, peripheral blood mononuclear cells were isolated from patients with VIT and healthy individuals. The present study revealed that the proportions of CD4+ T cells, Treg cells and T helper 1 (Th1) cells were decreased in patients with VIT, but those of Teff cells (Th17 and Th22 cells) were increased; additionally, Foxp3 expression was decreased, but the expression levels of interferon‑γ, interleukin (IL)‑17A and IL‑22 were increased. Furthermore, in patients with VIT, microRNA (miR)‑21‑5p expression was decreased, while that of STAT3 was increased. Further in vitro experiments in CD4+ T cells revealed that STAT3 was targeted by miR‑21‑5p. Functional analysis further indicated that miR‑21‑5p overexpression in Th17‑polarized CD4+ T cells decreased the proportion of Teff cells and associated cytokines, such as IL‑17A and IL‑22, but increased the proportion of Treg cells and Foxp3. However, the effects of miR‑21‑5p overexpression were partly reversed by STAT3 overexpression. Increased apoptosis of melanocytes was detected after co‑culture with Th17‑polarized CD4+ T cells in the presence of a miR‑21‑5p mimic. However, this indirect effect of the miR‑21‑5p mimic on melanocytes was decreased via STAT3 overexpression. Therefore, miR‑21‑5p may protect melanocytes via targeting STAT3 and regulating Treg/Teff balance. The current findings may provide a possible treatment method for managing VIT.

Emerging systemic JAK inhibitors in the treatment of atopic dermatitis: a review of abrocitinib, baricitinib, and upadacitinib

The Janus kinases (JAK) are a group of molecules, composed of JAK1, JAK2, JAK3, and tyrosine kinase 2 (TYK2), which are key components within the JAK–signal transducers and activators of transcription pathway, where cytokine receptor signaling takes place. These molecules play a foundational role in the underlying pathogenesis of multiple immune-related conditions such as atopic dermatitis (AD), rheumatoid arthritis, psoriatic arthritis, inflammatory bowel disease, and others. Thus far, JAK inhibitors for inflammatory conditions have only been marketed for the treatment of rheumatoid arthritis and psoriatic arthritis, but ongoing phase II and phase III clinical trials for other immune-mediated diseases, such as AD, have also shown promising results. This review summarizes the clinical data available from various trials and reports on the safety and efficacy of abrocitinib, baricitinib, and upadacitinib, the three oral systemic JAK inhibitors used in the treatment of AD. The safety and efficacy of JAK inhibitors for the treatment of AD are emerging in the literature. It is important that dermatologists are aware of any potential adverse events or risks associated with the use of JAK inhibitors in order to promote a higher standard of treatment and quality of living.

Cutaneous JAK Expression in Vitiligo

BACKGROUND

The Janus kinase-signal transducer and activator of transcription signaling pathway has been suggested as a promising therapeutic target in vitiligo. However, limited data is available on the cutaneous expression of JAK in vitiligo.

AIM

This study is designed to analyze the cutaneous expression patterns of JAK1, 2, and 3 in vitiligo and investigate their relation to the disease clinical parameters.

METHODS

This case-control study recruited 24 patients having active vitiligo and 20 age, sex, and skin type-matched healthy volunteers. Skin biopsies were obtained from patients (lesional, perilesional and nonlesional) and controls for assessment of JAK1, 2, and 3 expression using RT-PCR.

RESULTS

JAK1 and JAK3 were overexpressed in patients' skin compared to control skin and showed a stepwise pattern of upregulation from control to nonlesional, perilesional and lesional skin. However, JAK3 showed much stronger expression. In contrast JAK2 expression showed no significant difference in any of lesional, perilesional or nonlesional skin compared to control skin. JAK1 and JAK3 expression levels showed no correlation with neither the disease activity nor severity.

CONCLUSION

JAK1 and more prominently JAK3 are upregulated in vitiliginous skin and possibly contribute to the pathogenesis of the disease. Accordingly, selective JAK3/1 inhibition may provide a favorable therapeutic opportunity for vitiligo patients.This study is registered on the ClinicalTrials.gov Identifier: NCT03185312.

Melanoma and Vitiligo: In Good Company

Cutaneous melanoma represents the most aggressive form of skin cancer, whereas vitiligo is an autoimmune disorder that leads to progressive destruction of skin melanocytes. However, vitiligo has been associated with cutaneous melanoma since the 1970s. Most of the antigens recognized by the immune system are expressed by both melanoma cells and normal melanocytes, explaining why the autoimmune response against melanocytes that led to vitiligo could be also present in melanoma patients. Leukoderma has been also observed as a side effect of melanoma immunotherapy and has always been associated with a favorable prognosis. In this review, we discuss several characteristics of the immune system responses shared by melanoma and vitiligo patients, as well as the significance of occurrence of leukoderma during immunotherapy, with special attention to check-point inhibitors.