Immunometabolism in the pathogenesis of vitiligo

Proteomic analysis of plasma and urine for efficacy prediction biomarkers of Janus kinase inhibitors combined with phototherapy in vitiligo

The combination of Janus kinase inhibitors and narrowband ultraviolet B (NB-UVB) therapy is an effective treatment for vitiligo; however, reliable and convenient biomarkers for predicting treatment efficacy prior to therapy are currently lacking. The biomarker combination of pretreatment plasma C–C motif chemokine 5 and fibrinogen-like protein 1 levels, along with urine ezrin and glyceraldehyde 3-phosphate dehydrogenase levels, can predict the sensitivity to baricitinib combined with NB-UVB therapy in patients with vitiligo.

Metabolic syndrome and dermatological diseases: association and treatment

Metabolic syndrome (MetS) is a clinical syndrome associated with cardiovascular disease, diabetes, obesity, and dyslipidemia. Its primary features include dyslipidemia, hypertension, abdominal obesity, and insulin resistance (IR). Recently, research has revealed that MetS is not only a manifestation of internal metabolic disturbances but is also closely associated with various dermatological conditions, including inflammatory skin diseases, autoimmune skin diseases, and skin tumors. These studies have clarified the complex mechanisms underlying the interaction between MetS and these skin diseases, including IR, chronic inflammatory responses, and oxidative stress. This review summarizes the association between MetS and related dermatological conditions and their shared physiological mechanisms. It aims to provide clinicians with new therapeutic strategies and preventive measures to improve the treatment outcomes and quality of life of patients with skin conditions.

Emerging role of regulatory T cells in the immunopathogenesis of vitiligo and implications for treatment

Vitiligo is an autoimmune skin disease that targets pigment-producing melanocytes and results in depigmentation. This disfiguring condition frequently affects visible areas of the body and therefore causes a heavy psychological burden and a decreased quality of life. Although it remains intractable, the ever-growing understanding of its immunopathogenesis has dramatically shaped the treatment paradigm for vitiligo. With the impact of autoreactive cytotoxic T cells explained extensively, accumulating evidence suggests the unique role of regulatory T cells (Tregs) in the immune microenvironment of vitiligo. We systematically reviewed Treg deficiency, instability, reduced vitality and dysfunction in people with vitiligo, combined with novel findings regarding Treg function modulation in autoimmune backgrounds, including metabolic alteration, post-translational modifications and interaction with other immune cells. We further summarized classic and advanced Treg-targeted therapeutics in vitiligo practice and research. Herein, we share up-to-date knowledge of Tregs in vitiligo, providing insights into novel Treg-based therapeutic strategies.

Safety and efficacy of Simvastatin in the treatment of vitiligo: a systematic review and meta-analysis of randomized controlled trials

Vitiligo is an autoimmune skin disorder characterized by progressive depigmentation due to melanocyte destruction. Despite various treatment options, achieving complete repigmentation remains challenging. Simvastatin, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, has demonstrated anti-inflammatory and immunomodulatory effects, making it a promising candidate for vitiligo treatment. This systematic review and meta-analysis aimed to evaluate the efficacy and safety of Simvastatin in vitiligo treatment. A systematic search of PubMed, Scopus, Web of Science, and Cochrane Library was conducted following PRISMA guidelines. Only RCTs comparing Simvastatin with a control or pre-post Simvastatin assessments in vitiligo patients were included. Six RCTs with a total of 371 patients met the eligibility criteria. The primary outcomes analyzed were VASI reduction and excellent repigmentation response (≥ 75% repigmentation). Secondary outcomes included changes in total cholesterol, triglycerides, and low-density lipoprotein (LDL) levels. Meta-analyses were performed using a random-effects model, and heterogeneity was assessed using the I2 statistic. Simvastatin significantly reduced VASI scores (SMD = -0.30; 95% CI -0.52--0.07, p = 0.010; I2 = 0%). The likelihood of achieving excellent repigmentation (≥ 75%) was significantly higher in the Simvastatin group (OR = 6.54; 95% CI 1.08-38.42, p = 0.04; I2 = 0%). Additionally, Simvastatin led to a significant reduction in total cholesterol (-62.1 mg/dL; 95% CI -74.0--50.2, p < 0.00001; I2 = 0%), triglycerides (-65.08 mg/dL; 95% CI -89.81--40.35, p < 0.00001; I2 = 69%), and LDL (-66.13 mg/dL; 95% CI -77.50--54.76, p < 0.00001; I2 = 90%). Simvastatin demonstrates significant efficacy in vitiligo treatment, improving VASI scores and repigmentation while also lowering lipid levels. This is the first meta-analysis on this topic, providing evidence for Simvastatin as a potential adjunct therapy. Further large-scale RCTs are needed to validate these findings.

Metabolic anomalies in vitiligo: a new frontier for drug repurposing strategies

Vitiligo is a chronic autoimmune condition characterized by the destruction of melanocytes, leading to patchy loss of skin depigmentation. Although its precise cause remains unclear, recent evidence suggests that metabolic disturbances, particularly oxidative stress and mitochondrial dysfunction, may play a significant role in the pathogenesis of the disease. Oxidative stress is thought to damage melanocytes and trigger inflammatory responses, culminating in melanocyte immune-mediate destruction. Additionally, patients with vitiligo often exhibit extra-cutaneous metabolic abnormalities such as abnormal glucose metabolism, dyslipidemia, high fasting plasma glucose levels, high blood pressure, out of range C-peptide and low biological antioxidant capacity, suggesting a potential link between metabolic impairment and vitiligo development. This implies that the loss of functional melanocytes mirrors a more general systemic targetable dysfunction. Notably, therapies targeting metabolic pathways, particularly those involving mitochondrial metabolism, such as the peroxisome proliferator-activated nuclear receptor γ (PPARγ) agonists, are currently being investigated as potential treatments for vitiligo. PPARγ activation restores mitochondrial membrane potential, mitochondrial DNA copy number and, consequently, ATP production. Moreover, PPARγ agonists counteract oxidative stress, reduce inflammation, inhibit apoptosis, and maintain fatty acid metabolism, in addition to the well-known capability to enhance insulin sensitivity. Additionally, increasing evidence of a strong relationship between metabolic alterations and vitiligo pathogenesis suggests a role for other approved anti-diabetic treatments, like metformin and fibrates, in vitiligo treatment. Taken together, these data support the use of approaches alternative to traditional immune-suppressive treatments for the treatment of vitiligo.

Beyond skin deep: exploring the complex molecular mechanisms and holistic management strategies of vitiligo

Vitiligo is a multifactorial skin disorder characterized by the progressive loss of pigmentation due to the destruction of melanocytes, affecting 0.5-2% of the global population. This condition not only impacts physical appearance but also has profound psychosocial effects on patients. In this review, various aspects of vitiligo are explored, including its clinical forms, epidemiology, and underlying mechanisms. Advances in research have identified key molecular pathways, such as Wnt/β-Catenin, JAK-STAT, and AhR signaling, which are essential for melanocyte survival and immune regulation. These pathways provide valuable insights into the disease's progression and potential treatment targets. Furthermore, the role of microbial imbalances in the gut and skin microbiomes, stress-related factors, and nutritional deficiencies in influencing the onset and progression of vitiligo is investigated. The potential of herbal treatments to stimulate repigmentation is also discussed. By presenting a comprehensive overview, this review aims to deepen the understanding of vitiligo's complex pathology and foster the development of effective therapeutic strategies to enhance patient care.

Identifying potential biomarkers and molecular mechanisms related to arachidonic acid metabolism in vitiligo

Background

Numerous studies have reported that dysregulation of fatty acid metabolic pathways is associated with the pathogenesis of vitiligo, in which arachidonic acid metabolism (AAM) plays an important role. However, the molecular mechanisms of AAM in the pathogenesis of vitiligo have not been clarified. Therefore, we aimed to identify the biomarkers and molecular mechanisms associated with AAM in vitiligo using bioinformatics methods.

Methods

The GSE75819 and GSE65127 datasets were used in this study as the training and validation sets, respectively, along with 58 AAM-related genes (AAM-RGs). The differentially expressed genes (DEGs) between the lesional and control groups in the training set were identified through differential expression analysis. A biomarker-based nomogram was constructed to predict the risk of vitiligo.

Results

15 overlapping candidate genes were obtained between the DEGs and AAM-RGs. Machine-learning algorithms were used to identify six key genes as PTGDS, PNPLA8, FAAH, ABHD12, PTGS1, and MGLL. In both the training and validation sets, PTGDS, PNPLA8, and MGLL. In both the training and validation sets, PTGDS, PNPLA8, and MGLL were regarded as biomarkers. A nomogram based on these biomarkers showed potential for predicting the risk of vitiligo. Functional enrichment, immune cell infiltration, and regulatory network analyses were used to elucidate the molecular mechanisms.

Conclusion

In conclusion, PTGDS, PNPLA8, and MGLL were implicated in AAM to influence the pathogenesis of vitiligo. These findings offer insights into vitiligo treatment, although further research is needed for a comprehensive understanding.

Microbes, macrophages, and melanin: a unifying theory of disease as exemplified by cancer

It is widely accepted that cancer mostly arises from random spontaneous mutations triggered by environmental factors. Our theory challenges the idea of the random somatic mutation theory (SMT). The SMT does not fit well with Charles Darwin's theory of evolution in that the same relatively few mutations would occur so frequently and that these mutations would lead to death rather than survival of the fittest. However, it would fit well under the theory of evolution, if we were to look at it from the vantage point of pathogens and their supporting microbial communities colonizing humans and mutating host cells for their own benefit, as it does give them an evolutionary advantage and they are capable of selecting genes to mutate and of inserting their own DNA or RNA into hosts. In this article, we provide evidence that tumors are actually complex microbial communities composed of various microorganisms living within biofilms encapsulated by a hard matrix; that these microorganisms are what cause the genetic mutations seen in cancer and control angiogenesis; that these pathogens spread by hiding in tumor cells and M2 or M2-like macrophages and other phagocytic immune cells and traveling inside them to distant sites camouflaged by platelets, which they also reprogram, and prepare the distant site for metastasis; that risk factors for cancer are sources of energy that pathogens are able to utilize; and that, in accordance with our previous unifying theory of disease, pathogens utilize melanin for energy for building and sustaining tumors and metastasis. We propose a paradigm shift in our understanding of what cancer is, and, thereby, a different trajectory for avenues of treatment and prevention.

Focusing on the Dark Side of the Moon: Involvement of the Nonlesional Skin in Vitiligo

Research over the last decade has revealed that the normally pigmented skin of patients with vitiligo is not normal at all, as evidenced by alterations in cutaneous morphology and modifications in cellular and metabolic functions that ultimately drive immune activation against melanocytes. Furthermore, nonlesional skin is in a state of subclinical inflammation until triggered by internal and/or external exposomal events. Therefore, targeting early processes that drive immune dysregulation in normally pigmented skin may avoid or reduce melanocyte loss. Thus, shifting the focus to nonlesional skin may prevent the appearance of clinical manifestations of the disease rather than treating the lesions.

JAK inhibitors in immune regulation and treatment of vitiligo

Vitiligo, a disorder marked by hypopigmentation, significantly impacts patients' quality of life and mental health. This condition results from the reduction or dysfunction of melanocytes, which are crucial for skin and hair pigmentation. Current treatments include glucocorticoids, immunosuppressants, phototherapy, vitamin D3 analogues, and surgical interventions. Recent research has revealed that hyperactivation of Janus kinase (JAK) and its downstream signaling pathways intensifies cytotoxic T cell activity and weakens melanocytes' defense against environmental stressors. Additionally, the aberrant expression of pro-inflammatory cytokines such as Interferon-gamma (IFN-γ) and Tumor Necrosis Factor-alpha (TNF-α) plays a critical role in the pathogenesis of vitiligo by disrupting melanocyte function and promoting immune-mediated destruction. Clinical trials and basic research have demonstrated the efficacy of JAK inhibitors in modulating these cytokine pathways and promoting melanocyte repigmentation. This review provides a comprehensive analysis of JAK inhibitors, exploring their mechanisms and latest applications in regulating cytokine and skin immune responses, aiming to optimize their use in vitiligo therapy.

Markers of Metabolic Abnormalities in Vitiligo Patients

While vitiligo is primarily caused by melanocyte deficiency or dysfunction, recent studies have revealed a notable prevalence of metabolic syndrome (MetS) among patients with vitiligo. This suggests shared pathogenic features between the two conditions. Individuals with vitiligo often exhibit variations in triglyceride levels, cholesterol, and blood pressure, which are also affected in MetS. Given the similarities in their underlying mechanisms, genetic factors, pro-inflammatory signalling pathways, and increased oxidative stress, this study aims to highlight the common traits between vitiligo and metabolic systemic disorders. Serum analyses confirmed increased low-density lipoprotein (LDL) levels in patients with vitiligo, compared to physiological values. In addition, we reported significant decreases in folate and vitamin D (Vit D) levels. Oxidative stress is one of the underlying causes of the development of metabolic syndromes and is related to the advancement of skin diseases. This study found high levels of inflammatory cytokines, such as interleukin-6 (IL-6) and chemokine 10 (CXCL10), which are markers of inflammation and disease progression. The accumulation of insulin growth factor binding proteins 5 (IGFBP5) and advanced glycation end products (AGEs) entailed in atherosclerosis and diabetes onset, respectively, were also disclosed in vitiligo. In addition, the blood-associated activity of the antioxidant enzymes catalase (Cat) and superoxide dismutase (SOD) was impaired. Moreover, the plasma fatty acid (FAs) profile analysis showed an alteration in composition and specific estimated activities of FAs biosynthetic enzymes resembling MetS development, resulting in an imbalance towards pro-inflammatory n6-series FAs. These results revealed a systemic metabolic alteration in vitiligo patients that could be considered a new target for developing a more effective therapeutic approach.

Treatment of Refractory Segmental Vitiligo and Alopecia Areata in a Child with Upadacitinib and NB-UVB: A Case Report

Vitiligo and alopecia areata are both autoimmune skin diseases, and the chances of co-occurrence are very low. Conventional treatments often include glucocorticoids, which have many adverse reactions with long-term use and are difficult to achieve satisfactory results. Upadacitinib has been found to be effective in both vitiligo and alopecia areata due to partial overlap in pathogenic pathways. We report the successful treatment of vitiligo combined with alopecia areata in a nine-year-old child with upadacitinib in combination with UVB. The area of vitiligo and alopecia areata decreased significantly, and satisfactory results were obtained. It provides a new idea for the treatment of vitiligo complicated with alopecia areata in children.

Abnormal metabolism in melanocytes participates in the activation of dendritic cell in halo nevus

A comprehensive analysis of spatial transcriptomics was carried out to better understand the progress of halo nevus. We found that halo nevus was characterized by overactive immune responses, triggered by chemokines and dendritic cells (DCs), T cells, and macrophages. Consequently, we observed abnormal cell death, such as apoptosis and disulfidptosis in halo nevus, some were closely related to immunity. Interestingly, we identified aberrant metabolites such as uridine diphosphate glucose (UDP-G) within the halo nevus. UDP-G, accompanied by the infiltration of DCs and T cells, exhibited correlations with certain forms of cell death. Subsequent experiments confirmed that UDP-G was increased in vitiligo serum and could activate DCs. We also confirmed that oxidative response is an inducer of UDP-G. In summary, the immune response in halo nevus, including DC activation, was accompanied by abnormal cell death and metabolites. Especially, melanocyte-derived UDP-G may play a crucial role in DC activation.

The role of immune metabolism in skin cancers: implications for pathogenesis and therapy

The skin is a complex organ that serves as a critical barrier against external pathogens and environmental impact. Recent advances in immunometabolism have highlighted the intricate link between cellular metabolism and immune function, particularly in the context of skin cancers. This review aims to provide a comprehensive overview of the key metabolic pathways and adaptations that occur in immune cells during homeostasis and activation, and explore how metabolic reprogramming contributes to the pathogenesis of specific skin cancers. We discuss the complex interplay between tumor cells and infiltrating immune cells, which shapes the tumor microenvironment and influences disease outcomes. The review delves into the role of various metabolic pathways, such as glycolysis, oxidative phosphorylation, and lipid metabolism, in the regulation of immune cell function and their impact on the development and progression of skin cancers. Furthermore, we examine the potential of targeting metabolic pathways as a therapeutic strategy in skin cancers and discuss the challenges and future perspectives in this rapidly evolving field. By understanding the metabolic basis of skin immune responses, we can develop novel, personalized therapies for the treatment of skin cancers, ultimately improving patient outcomes and quality of life. The insights gained from this review will contribute to the growing body of knowledge in immunometabolism and its application in the management of skin cancers, paving the way for more effective and targeted interventions in the future.

Exosome-derived microRNAs: emerging players in vitiligo

Exosome-derived microRNAs (miRNAs) are biomacromolecules and nanoscale extracellular vesicles originating from intracellular compartments that are secreted by most cells into the extracellular space. This review examines the formation and function of exosomal miRNAs in biological information transfer, explores the pathogenesis of vitiligo, and highlights the relationship between exosomal miRNAs and vitiligo. The aim is to deepen the understanding of how exosomal miRNAs influence immune imbalance, oxidative stress damage, melanocyte-keratinocyte interactions, and melanogenesis disorders in the development of vitiligo. This enhanced understanding may contribute to the development of potential diagnostic and therapeutic options for vitiligo.

Exploring the roles and potential therapeutic strategies of inflammation and metabolism in the pathogenesis of vitiligo: a mendelian randomization and bioinformatics-based investigation

Introduction

Vitiligo, a common autoimmune acquired pigmentary skin disorder, poses challenges due to its unclear pathogenesis. Evidence suggests inflammation and metabolism's pivotal roles in its onset and progression. This study aims to elucidate the causal relationships between vitiligo and inflammatory proteins, immune cells, and metabolites, exploring bidirectional associations and potential drug targets.

Methods

Mendelian Randomization (MR) analysis encompassed 4,907 plasma proteins, 91 inflammatory proteins, 731 immune cell features, and 1400 metabolites. Bioinformatics analysis included Protein-Protein Interaction (PPI) network construction, Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. Subnetwork discovery and hub protein identification utilized the Molecular Complex Detection (MCODE) plugin. Colocalization analysis and drug target exploration, including molecular docking validation, were performed.

Results

MR analysis identified 49 proteins, 39 immune cell features, and 59 metabolites causally related to vitiligo. Bioinformatics analysis revealed significant involvement in PPI, GO enrichment, and KEGG pathways. Subnetwork analysis identified six central proteins, with Interferon Regulatory Factor 3 (IRF3) exhibiting strong colocalization evidence. Molecular docking validated Piceatannol's binding to IRF3, indicating a stable interaction.

Conclusion

This study comprehensively elucidates inflammation, immune response, and metabolism's intricate involvement in vitiligo pathogenesis. Identified proteins and pathways offer potential therapeutic targets, with IRF3 emerging as a promising candidate. These findings deepen our understanding of vitiligo's etiology, informing future research and drug development endeavors.

Identification of TNF-α as Major Susceptible Risk Locus for Vitiligo: A Systematic Review and Meta-Analysis Study in the Asian Population

INTRODUCTION

Vitiligo is a common depigmentation disorder characterized by defined white patches on the skin and affecting around 0.5% to 2% of the general population. Genetic association studies have identified several pre-disposing genes and single nucleotide polymorphisms (SNPs) for vitiligo pathogenesis; nonetheless, the reports are often conflicting and rarely conclusive. This comprehensive meta-analysis study was designed to evaluate the effect of the risk variants on vitiligo aetiology and covariate stratified vitiligo risk in the Asian population, considering all the studies published so far.

METHODS

We followed a systematic and comprehensive search to identify the relevant vitiligo-related candidate gene association studies in PubMed using specific keywords. After data extraction, we calculated, for the variants involved, the study-level unadjusted odds ratio, standard errors, and 95% confidence intervals by using logistic regression with additive, dominant effect, and recessive models using R software package (R, 3.4.2) "metafor." Subgroup analysis was performed using logistic regression (generalized linear model; "glm") of disease status on subgroup-specific genotype counts. For a better understanding of the likely biological function of vitiligo-associated variant obtained through the meta-analysis, in silico functional analyses, through standard publicly available web tools, were also conducted.

RESULTS

Thirty-one vitiligo-associated case-control studies on eleven SNPs were analysed in our study. In the fixed-effect meta-analysis, one variant upstream of TNF-α gene: rs1800629 was found to be associated with vitiligo risk in the additive (p = 4.26E-06), dominant (p = 1.65E-7), and recessive (p = 0.000453) models. After Benjamini-Hochberg false discovery rate (FDR) correction, rs1800629/TNF-α was found to be significant at 5% FDR in the dominant (padj = 1.82E-6) and recessive models (padj = 0.0049). In silico characterization revealed the prioritized variant to be regulatory in nature and thus having potential to contribute towards vitiligo pathogenesis.

CONCLUSION

Our study constitutes the first comprehensive meta-analysis of candidate gene-based association studies reported in the whole of the Asian population, followed by an in silico analysis of the vitiligo-associated variant. According to the findings of our study, TNF-α single nucleotide variant rs1800629G>A has a risk association, potentially contributing to vitiligo pathogenesis in the Asian population.

Oxidative Stress and Potential Antioxidant Therapies in Vitiligo: A Narrative Review

Vitiligo is a chronic skin disorder characterised by the loss of melanocytes and subsequent skin depigmentation. Although many theories have been proposed in the literature, none alone explains the pathogenesis of vitiligo. Oxidative stress has been identified as a potential factor in the pathogenesis of vitiligo. A growing body of evidence suggests that antioxidant therapies may offer a promising approach to managing this condition. This review summarises the potential mechanisms of oxidative stress and the types of melanocyte death in vitiligo. We also provide a brief overview of the most commonly studied antioxidants. Melanocytes in vitiligo are thought to be damaged by an accumulation of reactive oxygen species to destroy the structural and functional integrity of their DNA, lipids, and proteins. Various causes, including exogenous and endogenous stress factors, an imbalance between prooxidants and antioxidants, disruption of antioxidant pathways, and gene polymorphisms, lead to the overproduction of reactive oxygen species. Although necroptosis, pyroptosis, ferroptosis, and oxeiptosis are newer types of cell death that may contribute to the pathophysiology of vitiligo, apoptosis remains the most studied cell death mechanism in vitiligo. According to studies, vitamin E helps to treat lipid peroxidation of the skin caused by psoralen ultra-violet A treatment. In addition, Polypodium leucotomos increased the efficacy of psoralen ultra-violet A or narrow-band ultraviolet B therapy. Our review provides valuable insights into the potential role of oxidative stress in pathogenesis and antioxidant-based supporting therapies in treating vitiligo, offering a promising avenue for further research and the development of effective treatment strategies.