Cutaneous JAK Expression in Vitiligo

Role of Cytokines and Chemokines in Vitiligo and Their Therapeutic Implications

Vitiligo is a persistent autoimmune disease characterized by progressive depigmentation of the skin caused by the selective destruction of melanocytes. Although its etiopathogenesis remains unclear, multiple factors are involved in the development of this disease, from genetic and metabolic factors to cellular oxidative stress, melanocyte adhesion defects, and innate and adaptive immunity. This review presents a comprehensive summary of the existing knowledge on the role of different cellular mechanisms, including cytokines and chemokines interactions, in the pathogenesis of vitiligo. Although there is no definitive cure for vitiligo, notable progress has been made, and several treatments have shown favorable results. A thorough understanding of the basis of the disease uncovers promising drug targets for future research, providing clinical researchers with valuable insights for developing improved treatment options.

A Mendelian randomization study on the causal effects of circulating cytokines on the risk of vitiligo

Background

Accumulating evidence reveals an association between circulating cytokine levels and vitiligo. However, the causal association between circulating cytokine levels and vitiligo remains unrevealed.

Methods

We performed a two-sample Mendelian randomization (MR) analysis using a genome-wide association study of the 41 cytokines dataset, which was conducted with 3 Finnish cohorts (n = 8,293). Vitiligo data were acquired from strictly defined vitiligo data collected by FinnGenbiobank analysis, which included 207,613 European ancestors (131 vitiligo patients, 207,482 controls). The inverse-variance weighted (IVW) method, weighted median (WME), simple model, weighted model, and MR-Egger were used to determine the changes in vitiligo pathogenic cytokine taxa, followed by sensitivity analysis, including horizontal pleiotropy analysis. The MR Steiger test evaluated the strength of a causal association, and the leave-one-out method was used to assess the reliability of the results. The possibility of reverse causality was also investigated using a reverse MR study.

Results

We observed that rising IL-4 levels generated an enhanced probability of vitiligo in IVW (OR 2.72, 95%CI 1.19-6.22, p = 0.018). According to the results of the MR analysis, there were causal links between IL-4 and vitiligo. Results were steady after sensitivity and heterogeneity analyses.

Conclusion

Our research reveals that a genetically determined increased level of circulating IL-4 may be linked to a higher risk of developing vitiligo. The development of innovative treatment approaches (such as tofacitinib or dupilumab) that focus on blocking IL-4 as a novel way of preventing and treating vitiligo is significantly impacted by our findings.

A Case of Vitiligo Combined with Systemic Lupus Erythematosus Treated with Tofacitinib

Vitiligo is a skin depigmentation disease resulting from melanocyte destruction and often co-occurring with autoimmune disorders like hyperthyroidism, alopecia areata, pernicious anemia, and systemic lupus erythematosus (SLE). Although various traditional treatments exist for vitiligo, their effectiveness varies considerably. This report presents a unique case of a vitiligo patient with concomitant systemic lupus erythematosus. Remarkably, after a 30-day course of treatment with tofacitinib, complete repigmentation of the white macular rash was achieved, and there were no adverse drug reactions. These findings provide compelling evidence for the efficacy and safety of oral JAK inhibitors, such as tofacitinib, in vitiligo treatment. Additionally, JAK inhibitors can yet be regarded as a promising new treatment option for vitiligo patients with concurrent autoimmune diseases.

Improvements in immune/melanocyte biomarkers with JAK3/TEC family kinase inhibitor ritlecitinib in vitiligo

BACKGROUND

Vitiligo is an autoimmune depigmenting disorder with no effective and safe treatments. Its pathogenesis is not fully elucidated.

OBJECTIVE

This substudy of a randomized, double-blind, placebo-controlled phase 2b trial (NCT03715829) evaluated effects of ritlecitinib, an oral JAK3/TEC family kinase inhibitor, on skin and blood biomarkers in participants with nonsegmental vitiligo (NSV).

METHODS

Sixty-five adults with NSV participated in the substudy and received daily treatment for 24 weeks with placebo (n = 14) or ritlecitinib with or without a 4-week loading dose: 200 (loading dose)/50 mg (n = 13), 100/50 mg (n = 12), 50 mg (n = 11), 30 mg (n = 8), or 10 mg (n = 6). Skin (lesional and nonlesional) biopsy samples were obtained at baseline and at 4 and 24 weeks. Changes from baseline to weeks 4 and 24 in skin and blood molecular and cellular biomarkers were evaluated by RNA sequencing, quantitative real-time PCR, proteomic analysis, and flow cytometry.

RESULTS

Ritlecitinib-treated groups showed downregulation of immune biomarkers and upregulation of melanocyte-related markers at weeks 4 and 24 compared to baseline and/or placebo. Significant reductions were seen in CD3+/CD8+ T-cell infiltrates, with significant increases in melanocyte markers (tyrosinase; Melan-A) in NSV lesions in the 50 mg ritlecitinib groups (both P < .05). There was significant, dose-dependent downregulation in T-cell activation, NK, cytotoxic, and regulatory markers in lesional skin (IL-2, IL2-RA, IL-15, CCR7, CD5, CRTAM, NCR1, XCL1, KIR3DL1, FASLG, KLRD; P < .05). TH1 and TH2 markers were also downregulated in lesional skin and blood in a dose-dependent manner (P < .05). Changes in immune biomarkers correlated with clinical response.

CONCLUSIONS

Ritlecitinib significantly downregulated proinflammatory biomarkers and increased melanocyte products in skin and blood of participants with NSV, suggesting its potential in treatment. Ritlecitinib-mediated changes positively correlated with clinical response.

JAK inhibitors in vitiligo: what they hit and what they miss - an immunopathogenesis based exposition of existing evidence

INTRODUCTION

Vitiligo is an autoimmune disorder which presents as depigmented macules due to selective loss of melanocytes. Heightened expression of Janus Kinase Signal transducers and activators of transcription (JAK STAT) pathway, which mediate cytokines action, suggest that targeting this signaling pathway may be an effective option.

AREAS COVERED

A PubMed search was carried out with the broad key words 'JAK,' 'vitiligo' from 2016 to 2023. We also analyzed papers where tissue-based JAK expression was studied, with or without concomitant treatment with JAK inhibitors. We address the role of JAK inhibitors in vitiligo and their effect on repigmentation of lesions.

EXPERT OPINION

While JAK inhibitors help in cessation of disease progression, they have no in vivo action on melanocyte proliferation and hence cannot result in re-pigmentation as a monotherapy. There is a need for tissue-based JAK and cytokine-based studies with post-treatment expression data to validate the role of this class of drugs in vitiligo. There is as yet no data to suggest that selective JAK inhibitors are superior to pan JAK inhibitors for vitiligo. JAK inhibitors are useful in active disease and effectively modulate the cytokine mediated autoimmune dammage and makes them singularly superior to oral glucocorticosteroids.

Treatment update for vitiligo based on autoimmune inhibition and melanocyte protection

INTRODUCTION

The treatment of vitiligo remains challenging due to the complexity of its pathogenesis, influenced by genetic factors, oxidative stress and abnormal cell adhesion that collectively impact melanocyte survival and trigger immune system attacks, resulting in melanocyte death. Melanocytes in vitiligo are believed to exhibit genetic susceptibility and defects in cellular mechanisms, such as defects in autophagy, that reduce their ability to resist oxidative stress, leading to increased expression of the pro-inflammatory protein HSP70. The low expression of adhesion molecules, such as DDR1 and E-cadherin, accelerates melanocyte damage and antigen exposure. Consequently, autoimmune attacks centered on IFN-γ-CXCR9/10-CXCR3-CD8⁺ T cells are initiated, causing vitiligo.

AREAS COVERED

This review discusses the latest knowledge on the pathogenesis of vitiligo and potential therapeutic targets from the perspective of suppressing autoimmune attacks and activating melanocytes functions.

EXPERT OPINION

Vitiligo is one of the most challenging dermatological diseases due to its complex pathogenesis with diverse therapeutic targets. Immune suppression, such as corticosteroids and emerging JAK inhibitors, has proven effective in disease progression. However, during the early stages of the disease, it is also important to optimize therapeutic strategies to activate melanocytes for alleviating oxidative stress and improving treatment outcomes.

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.

Vitiligo: An immune disease and its emerging mesenchymal stem cell therapy paradigm

Melanocyte damage, innate immune response, adaptive immune response, and immune inflammatory microenvironment disorders are involved in the development of the immunological pathogenic mechanism of vitiligo. Mesenchymal stem cells are considered an ideal type of cells for the treatment of vitiligo owing to their low immunogenicity, lower rates of transplant rejection, and ability to secrete numerous growth factors, exosomes, and cytokines in vivo. The regulation of signaling pathways related to oxidative stress and immune imbalance in the immunological pathogenesis of vitiligo can improve the immune microenvironment of tissue injury sites. In addition, co-transplantation with melanocytes can reverse the progression of vitiligo. Therefore, continuous in-depth research on the immunopathogenic mechanism involved in this disease and mesenchymal stem cell-based therapy is warranted for the treatment of vitiligo in the future.

Janus Kinase Inhibitors in the Treatment of Vitiligo: A Review

Vitiligo is a multifactorial reversible skin disorder characterized by distinct white patches that result from melanocyte destruction. Activated CXCR3⁺ CD8⁺ T cells promote melanocyte detachment and apoptosis through interferon-gamma (IFN-γ secretion and chemokines secreted by keratinocytes through the Janus kinase (JAK)/signal transducer and activator of transcription (STAT)-1 signaling pathway results in further recruitment of CXCR3⁺ CD8⁺ T cells and the formation of a positive-feedback loop. JAK inhibitors target the JAK/STAT pathway and are now approved to treat many immune-related diseases. In the treatment of vitiligo, JAK inhibitors, including ruxolitinib, baricitinib, and tofacitinib, are effective, supporting the implication of the IFN-γ-chemokine signaling axis in the pathogenesis of vitiligo. However, more studies are required to determine the ideal dosage of JAK inhibitors for the treatment of vitiligo, and to identify other inflammatory pathways that may be implicated in the pathogenesis of this condition.

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.

Vitiligo: What's old, what's new

Vitiligo is an acquired pigmentary disorder afflicting 0.5-2% of the world population for both sexes and all races with a capricious and unpredictable course. It has a complex etiology and varies in its manifestation, progression and response to treatment. Even if the precise aetiology and pathobiology of the disease are complex and still debated, recent evidence supports that vitiligo is a T CD8+ cell-mediated autoimmune disease triggered by oxidative stress. To date no clinical, biological and histological criteria allow us to establish the prognosis with certainty. The choice of the best therapy for adult and childhood vitiligo is based on various factors, such as the patient's age, psychological condition and expectations, distribution and extension of skin lesions, type of vitiligo (stable or not) and availability and cost of therapeutic options. Since vitiligo has a deep psychological impact on patients and their quality of life, treating the disease is very important. As dermatologists, we have important goals in the treatment of vitiligo patients: stabilization of the disease progression, repigmentation of the lesions and especially the persistence of the aforementioned repigmentation. Although several medical and surgical therapeutic options have been proposed, no definite cure has yet been developed and the long-term persistence of repigmentation is unpredictable. We review the different therapeutic options with particular attention on the recurrence rate.