The Role of TRM Cells in the Pathogenesis of Vitiligo-A Review of the Current State-Of-The-Art

Tissue-resident memory T cells in immunotherapy and immune-related adverse events by immune checkpoint inhibitor

Tissue-resident memory T cells (TRM) are a specialized subset of T cells that reside in tissues and provide long-term protective immunity against pathogens that enter the body through that specific tissue. TRM cells have specific phenotype and reside preferentially in barrier tissues. Recent studies have revealed that TRM cells are the main target of immune checkpoint inhibitor immunotherapy since their role in cancer immunosurveillance. Furthermore, TRM cells also play a crucial part in pathogenesis of immune-related adverse events (irAEs). Here, we provide a concise review of biological characteristics of TRM cells, and the major advances and recent findings regarding their involvement in immune checkpoint inhibitor immunotherapy and the corresponding irAEs.

Topical application of simvastatin acid sodium salt and atorvastatin calcium salt in vitiligo patients. Results of the randomized, double-blind EVRAAS pilot study

Contemporary treatment of vitiligo remains a great challenge to practitioners. The vast majority of currently conducted clinical trials of modern therapeutic methods are focused on systemic medications, while there is only a very limited number of reports on new topical treatment in vitiligo. With their pleiotropic activities statins turned out to be efficient in the treatment of various autoimmune/autoinflammatory disorders. The randomized, double-blind placebo-controlled study of topical administration of the active forms of simvastatin and atorvastatin has been designed to evaluate their efficacy in patients with vitiligo. The study was registered in clinicaltrials.gov (registration number NCT03247400, date of registration: 11th August 2017). A total of 24 patients with the active form of non-segmental vitiligo were enrolled in the study. The change of absolute area of skin lesions, body surface area and vitiligo area scoring index were evaluated throughout the 12 week application of ointments containing simvastatin and atorvastatin. Measurements were performed with planimetry and processed using digital software. Use of active forms of simvastatin and atorvastatin did not result in a significant repigmentation of the skin lesions throughout the study period. Within the limbs treated with topical simvastatin, inhibition of disease progression was significantly more frequent than in the case of placebo (p = 0.004), while the difference was not statistically significant for atorvastatin (p = 0.082). Further studies of topical simvastatin in vitiligo patients should be considered.

Heterogeneity and plasticity of tissue-resident memory T cells in skin diseases and homeostasis: a review

Skin tissue-resident memory T (Trm) cells are produced by antigenic stimulation and remain in the skin for a long time without entering the peripheral circulation. In the healthy state Trm cells can play a patrolling and surveillance role, but in the disease state Trm cells differentiate into various phenotypes associated with different diseases, exhibit different localizations, and consequently have local protective or pathogenic roles, such as disease recurrence in vitiligo and maintenance of immune homeostasis in melanoma. The most common surface marker of Trm cells is CD69/CD103. However, the plasticity of tissue-resident memory T cells after colonization remains somewhat uncertain. This ambiguity is largely due to the variation in the functionality and ultimate destination of Trm cells produced from memory cells differentiated from diverse precursors. Notably, the presence of Trm cells is not stationary across numerous non-lymphoid tissues, most notably in the skin. These cells may reenter the blood and distant tissue sites during the recall response, revealing the recycling and migration potential of the Trm cell progeny. This review focuses on the origin and function of skin Trm cells, and provides new insights into the role of skin Trm cells in the treatment of autoimmune skin diseases, infectious skin diseases, and tumors.

Dietary habits in adult Japanese patients with vitiligo

Vitiligo is an autoimmune skin disease with acquired depigmentation. Dietary habits may modulate the pathogenesis of vitiligo. We evaluated dietary habits in adult Japanese patients with nonsegmental vitiligo, and compared their results with those of age- and sex-matched controls. We also examined the relationship between dietary habits and Vitiligo Area Scoring Index (VASI), or vitiligo on different anatomical sites. The intakes of energy, nutrients, and foods in the participants were analyzed using a brief-type self-administered diet history questionnaire. Patients with vitiligo showed higher body mass index (BMI) and lower intakes of manganese, vitamin D, pulses, and confection, compared with controls. Multivariate logistic regression analysis showed that vitiligo was associated with high BMI. VASI was higher in males than in females, and negatively correlated with age or intakes of potatoes and vegetables other than green/yellow vegetables. Linear multivariate regression analysis showed that high VASI was associated with younger age. Multivariate logistic regression analysis showed that moderate to severe vitiligo (VASI ≥ 4.25) was associated with male sex and longer disease duration. Multivariate logistic regression analyses showed the following association with vitiligo on respective anatomical sites: high intake of eggs and dairy products and high VASI on the head or neck, high intake of oils and fats and high VASI on the trunk, high intake of cereals and high VASI on the upper limbs, male sex and high VASI on the lower limbs, and high BMI and high VASI on the hands or feet. In conclusion, the control of obesity might have prophylactic or therapeutic effects on vitiligo.

Compromised melanocyte survival due to decreased suppression of CD4+ & CD8+ resident memory T cells by impaired TRM-regulatory T cells in generalized vitiligo patients

Regulatory T cells (Tregs) are involved in the suppression of activated T cells in generalized vitiligo (GV). The study was aimed to investigate resident memory (TRM)-Tregs and antigen-specific Tregs' numbers and functional defects in 25 GV patients and 20 controls. CD4+ & CD8+ TRM cell proliferation was assessed by BrDU assay; production of IL-10, TGF-β, IFN-γ, perforin and granzyme B were assessed by ELISA and enumeration of TRM cells was done by flowcytometry. GV patients showed significantly increased frequency and absolute count of CD4+ & CD8+ TRM cells in lesional (L), perilesional (PL) and non-lesional (NL) skin compared to controls (p = 0.0003, p = 0.0029 & p = 0.0115, respectively & p = 0.0003, p = 0.003 & p = 0.086, respectively). Whereas, TRM-Treg (p < 0.0001 & p = 0.0015) and antigen-specific Tregs (p = 0.0014 & p = 0.003) exhibited significantly decreased frequency and absolute counts in L & PL skin. GV patients showed reduced suppression of CD8+ & CD4+ TRM cells (with increased IFN-γ, perforin & granzyme B) and decreased TRM-Tregs and antigen-specific Tregs (with decreased IL-10 & TGF-β production) and reduced proliferation of SK-Mel-28 cells in co-culture systems. Immunohistochemistry revealed increased expression of TRM stimulating cytokines: IL-15 & IL-17A and reduced expression of TGF-β & IL-10 in L, PL, NL skins compared to controls. These results for the first time suggest that decreased and impaired TRM-Tregs and antigen-specific Tregs are unable to suppress CD4+ & CD8+ TRMs' cytotoxic function and their proliferation due to decrease production of immunosuppressive cytokines (IL-10 & TGF-β) and increased production of TRM based IFN-γ, perforin and granzyme B production, thus compromising the melanocyte survival in GV.

Etiopathogenesis and Emerging Methods for Treatment of Vitiligo

Vitiligo is an acquired chronic depigmenting disorder of skin. It is mostly asymptomatic and characterized by amelanotic macules and patches that affects 0.5% to 2% of the world's population. The etiology of vitiligo has not been clearly elucidated and multiple theories have been proposed regarding the causes of the disorder. Among the most prevalent theories, the genetic predisposition, oxidative stress theory, promotion of cellular stress and pathologic influence of lymphocytes T have been highlighted. As a result of increases in in-depth knowledge concerning the pathogenetic processes in vitiligo, we review the most recent information concerning its etiopathogenesis and treatment methods including topical and oral Janus kinase inhibitors, prostaglandins and their analogues, namely afamelanotide, Wnt/β-catenin-signaling agonists and cell-based therapies. Topical ruxolitinib has been registered for vitiligo treatment, whereas other agents as oral ritlecitinib, afamelanotide and latanoprost have been studied in ongoing clinical trials. New highly effective therapeutic strategies may be developed thanks to molecular and genetic studies.

Vitiligo Treatments: Review of Current Therapeutic Modalities and JAK Inhibitors

Vitiligo is a chronic autoimmune disease characterized by loss of pigment of the skin, affecting 0.5-2% of the population worldwide. It can have a significant impact on patients' quality of life. In recent years, there has been significant progress in our understanding of the pathogenesis of vitiligo. It is believed that vitiligo develops due to a complex combination of genetics, oxidative stress, inflammation, and environmental triggers. Conventional treatments include camouflage, topical corticosteroids, topical calcineurin inhibitors, oral corticosteroids, phototherapy, and surgical procedures, with the treatment regimen dependent on the patient's preferences and characteristics. With increased understanding of the importance of the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway in the pathogenesis of vitiligo, treatment has expanded to include the first US FDA-approved cream to repigment patients with vitiligo. This review summarizes our understanding of the major mechanisms involved in the pathogenesis of vitiligo and its most common available treatments.

Efficacy and safety of oral ritlecitinib for the treatment of active nonsegmental vitiligo: A randomized phase 2b clinical trial

BACKGROUND

Vitiligo is a chronic autoimmune disorder characterized by depigmented patches of the skin.

OBJECTIVE

To evaluate the efficacy and safety of ritlecitinib, an oral JAK3 (Janus kinase)/TEC (tyrosine kinase expressed in hepatocelluar carcinoma) inhibitor, in patients with active nonsegmental vitiligo in a phase 2b trial (NCT03715829).

METHODS

Patients were randomized to once-daily oral ritlecitinib ± 4-week loading dose (200/50 mg, 100/50 mg, 30 mg, or 10 mg) or placebo for 24 weeks (dose-ranging period). Patients subsequently received ritlecitinib 200/50 mg daily in a 24-week extension period. The primary efficacy endpoint was percent change from baseline in Facial-Vitiligo Area Scoring Index at week 24.

RESULTS

A total of 364 patients were treated in the dose-ranging period. Significant differences from placebo in percent change from baseline in Facial-Vitiligo Area Scoring Index were observed for the ritlecitinib 50 mg groups with (-21.2 vs 2.1; P < .001) or without (-18.5 vs 2.1; P < .001) a loading dose and ritlecitinib 30 mg group (-14.6 vs 2.1; P = .01). Accelerated improvement was observed after treatment with ritlecitinib 200/50 mg in the extension period (n = 187). No dose-dependent trends in treatment-emergent or serious adverse events were observed across the 48-week treatment.

LIMITATIONS

Patients with stable vitiligo only were excluded.

CONCLUSIONS

Oral ritlecitinib was effective and well tolerated over 48 weeks in patients with active nonsegmental vitiligo.

Impacts of exposure to topical calcineurin inhibitors on metabolism in vitiligo infants

BACKGROUND

Tacrolimus ointment is a recently developed topical immunomodulator that has been approved for use in patients with vitiligo older than 2 years. Concern regarding potential systemic toxic effects has limited treatment options for children younger than 2 years. We wanted to determine whether topical tacrolimus therapy is safe and effective in patients with vitiligo younger than 2 years.

METHODS

The present 6-month clinical trial was conducted to evaluate the efficacy and safety of 0.03% tacrolimus in the treatment of vitiligo in children under 2 years of age. Meanwhile, serum and urine samples were collected, and liquid chromatography-mass spectrometry was performed to generate the serum and urine metabolic profile data of patients and healthy controls.

RESULTS

The overall response rate at the sixth month, which was defined by the degree of re-pigmentation, was 100%. As revealed by blood monitoring and metabolite detection 6 months later, there was no difference between the treatment group and the control group. There is no evidence that long-term topical application of 0.03% tacrolimus ointment will cause metabolite or other physical changes in the body.

CONCLUSIONS

Tacrolimus ointment appears to be effective and safe in the treatment of vitiligo in children younger than 2 year.

TRIAL REGISTRATION

http://www.chictr.org.cn identifier: ChiCTR 2100045920.

IMPACT

We first reported the efficacy and safety of topical application of 0.03% tacrolimus ointment in infants with vitiligo characterized by the metabolites. There is no evidence that long-term topical application of 0.03% tacrolimus ointment will cause metabolite or other physical changes in the body. This study provide evidence for the TCI treatment of infants with vitiligo.

Structural basis for the mutation-induced dysfunction of the human IL-15/IL-15α receptor complex

In silico strategies offer a reliable, fast, and inexpensive, way compared to the clumsy in vitro approaches to boost understanding of the effect of amino acid substitution on the structure and consequently the associated function of proteins. In the present work, we report an atomistic-based, reliable in silico structural and energetic framework of the interactions between the receptor-binding domain of the Interleukin-15 (IL-15) protein and its receptor Interleukin-15α (IL-15α), consequently, providing qualitative and quantitative details of the key molecular determinants in ligand/receptor recognition. Molecular dynamics simulations were used to investigate the dynamic behavior of the specific binding between IL-15 and IL-15α followed by estimation of the free energies via molecular mechanics/generalized Born surface area (MM/GBSA). In particular, residues Y26, E46, E53, and E89 of the IL-15 protein receptor-binding domain are identified as main hot spots, shaping and governing the stability of the assembly. These results can be used for the development of neutralizing antibodies and the effective structure-based design of protein-protein interaction inhibitors against the so-called orphan disease, vitiligo.

Transplantation of autologous epidermal melanocyte-keratinocyte cells suspension for cell therapy of vitiligo: A clinical evaluation and biometric assessment

INTRODUCTION

Among several surgical treatments, the use of transplantation of epidermal cultured melanocytes or melanocytes-keratinocytes cell suspension has gained many researchers and dermatologists' attention as a new technique for the treatment of vitiligo. The present study aimed to transplant autologous epidermal melanocytes-keratinocytes cell suspension for the treatment of vitiligo.

METHODS

In this study, 15 volunteer patients aged between 18 and 45 years old were studied. The autologous melanocytes-keratinocytes cell suspension was then transplanted to the region after dermabrasion. The included patients were evaluated by VisioFace, MPA9, and Skin Scanner-DUB once before and 1, 2, and 6 months after the transplantation, while the extents of stainability and changes in the transplanted region were recorded.

RESULTS

The color contrast between the lesion and normal skin significantly decreased after 1, 2, and 6 months of the melanocytes transplantation compared with the pre-procedure (13.8 ± 0.45 before vs. 12.9 ± 0.43, 12.2 ± 0.45, and 10.2 ± 0.34 at months 1, 2, and 6, p < 0.001). Furthermore, melanin index significantly increased six months after cell transplantation compared to the pretreatment (168.3 ± 4.22 vs. 130.5 ± 3.98, p < 0.001).

CONCLUSION

Transplantation of melanocytes cells with dermabrasion can be effective on vitiligo improvement, so it is recommended.

Current Concepts of Vitiligo Immunopathogenesis

Vitiligo is an acquired immune-mediated disorder of pigmentation clinically characterized by well-defined depigmented or chalk-white macules and patches on the skin. The prevalence of vitiligo varies by geographical area, affecting 0.5% to 2% of the population. The disease imposes a significant psychological burden due to its major impact on patients’ social and emotional aspects of life. Given its autoimmune background, vitiligo is frequently associated with other autoimmune diseases or immune-mediated diseases. Vitiligo is a multifaceted disorder that involves both genetic predisposition and environmental triggers. In recent years, major predisposing genetic loci for the development of vitiligo have been discovered. The current findings emphasize the critical role of immune cells and their mediators in the immunopathogenesis of vitiligo. Oxidative-stress-mediated activation of innate immunity cells such as dendritic cells, natural killer, and ILC-1 cells is thought to be a key event in the early onset of vitiligo. Innate immunity cells serve as a bridge to adaptive immunity cells including T helper 1 cells, cytotoxic T cells and resident memory T cells. IFN-γ is the primary cytokine mediator that activates the JAK/STAT pathway, causing keratinocytes to produce the key chemokines CXCL9 and CXCL10. Complex interactions between immune and non-immune cells finally result in apoptosis of melanocytes. This paper summarizes current knowledge on the etiological and genetic factors that contribute to vitiligo, with a focus on immunopathogenesis and the key cellular and cytokine players in the disease’s inflammatory pathways.

Combination of epidermal keratinocyte - melanocyte cells suspension and microneedling: Safe surgical approach in vitiligo

INTRODUCTION

Vitiligo is a skin disease that is associated with impaired skin immune systems and pigment degradation in skin melanocyte cells. Despite the significant impact of the disease on the quality of life of patients, treatment of the disease using effective method such as the transplantation of uncultivated melanocytes was considered by researchers around the world. The goal of this research was to use microneedling to transplant epidermal keratinocyte-melanocyte cells suspension for the treatment of vitiligo patients.

METHODS

In this study, 15 male and female vitiligo in face region patients aged 18 to 45 years were studied. In this study, melanocyte-keratinocyte cells suspension was sprayed. Patients underwent microneedling treatment after spraying the cells. Before and after transplantation, patients were biometrically examined, and the quantity of pigmentation and changes in the transplanted region were documented. Statistical software was used to examine the results.

RESULTS

The color difference between the lesion area and normal skin in one, two, and six months after treatment with cell suspension was significantly reduced compared to before treatment (by 48.95 %). Moreover, the amount of melanin was significantly increased 6 months after treatment compared to before treatment (129.8±4.16 vs. 195.2±3.54, P = 0.000). A significant decrease in skin brightness in the skin of the lesion area was observed compared to normal skin, 6 months after treatment compared to before treatment (43.7±1.44 vs. 27.9±1.24, P = 0.000).

CONCLUSION

Epidermal keratinocyte - melanocyte cells suspension in combination with microneedling could be considered as an effective treatment of vitiligo.

Patho-immunological mechanisms of vitiligo: the role of the innate and adaptive immunities and environmental stress factors

Epidermal melanocyte loss in vitiligo, triggered by stresses ranging from trauma to emotional stress, chemical exposure or metabolite imbalance, to the unknown, can stimulate oxidative stress in pigment cells, which secrete damage-associated molecular patterns that then initiate innate immune responses. Antigen presentation to melanocytes leads to stimulation of autoreactive T-cell responses, with further targeting of pigment cells. Studies show a pathogenic basis for cellular stress, innate immune responses and adaptive immunity in vitiligo. Improved understanding of the aetiological mechanisms in vitiligo has already resulted in successful use of the Jak inhibitors in vitiligo. In this review, we outline the current understanding of the pathological mechanisms in vitiligo and locate loci to which therapeutic attack might be directed.

The Clinical Significance of Mesenteric Lymphocytes in Human Colorectal Cancer

Objective

The mesentery is a potential site of residual tumor in patients with colorectal cancer (CRC). However, the mesenteric immune microenvironment remains unclear. In this study, we investigated the immune landscape of the mesentery, particularly the role of lymphocytes and its association with the clinicopathological characteristics of CRC.

Methods

Flow cytometry was used to detect lymphocytes in the paired mesenteric tissue specimens adjacent to the colorectal tumors and normal mesenteric tissue specimens 10 cm away from the colorectal tumor edge and preoperative peripheral blood samples obtained from patients with CRC who underwent surgery. T-distributed stochastic neighbor embedding was utilized to analyze multiparameter flow cytometry data. Multiplex immunohistochemistry was performed to evaluate T cells subsets in the paired mesentery adjacent to the colorectal tumors and normal mesentery. The Fisher’s exact test and non-parametric Wilcoxon’s matched-pairs tests were used for statistical analysis. The non-parametric Mann-Whitney U test was used to determine associations between percentage data and clinical parameters of patients with CRC.

Results

We found that immune cells in the normal mesentery were mainly of lymphoid lineage. Compared with peripheral blood, the normal mesentery showed decreased NK cells and the CD4/CD8 ratio and increased CD3⁺ CD56⁺, memory CD4⁺ T, memory CD8⁺ T, CD4⁺ tissue-resident memory T (TRM), and CD8⁺ TRM cells. Compared with the normal mesentery, the mesentery adjacent to the colorectal tumor showed increased B and regulatory T cells and decreased NK, CD3⁺ CD56⁺, CD4⁺ TRM, and CD8⁺ TRM cells. Moreover, memory CD8⁺ T cells and plasmablasts are negatively correlated with the depth of invasion of CRC. Increased memory CD4⁺ T cells are associated with distant metastasis of CRC and high preoperative serum carcinoembryonic antigen levels.

Conclusion

The mesentery shows a specific immune microenvironment, which differs from that observed in peripheral blood. CRC can alter the mesenteric immune response to promote tumor progression.

Emerging role of Tissue Resident Memory T cells in vitiligo: From pathogenesis to therapeutics

Vitiligo is an acquired depigmenting disorder which affects both skin and mucous membranes and autoimmunity has been strongly suggested to play a role in loss of melanocytes. The recurrence of skin macules at the same sites where they were observed prior to the treatment, suggests the existence of Tissue Resident Memory T cells (TRMs) that persist within the skin or peripheral tissues with a longer survivability. Emerging studies have shown that reactivation of these skin TRMs results into autoreactive TRM cells in various autoimmune diseases including vitiligo. This review focuses on different subsets (CD8⁺ TRMs and CD4⁺ TRMs) of TRM cells, their retention and survivability in the skin along with their pathomechanisms leading to melanocyte death and progression of vitiligo. In addition, the review describes the TRM cells as potential targets for developing effective therapeutics of vitiligo.

Developing a JAK Inhibitor for Targeted Local Delivery: Ruxolitinib Cream

Named after the two-faced Roman god of doorways, Janus kinases (JAKs) represent a class of tyrosine kinases. The JAK signaling pathway is pivotal for the downstream signaling of inflammatory cytokines, including interleukins, interferons, and multiple growth factors. This article provides an overview of the JAK pathway and signaling, its significance in immune-mediated dermatologic diseases and the development of a targeted, localized option of a selective JAK inhibitor, ruxolitinib cream. In the early 1990s, various discovery and clinical development programs were initiated to explore pharmaceutical inhibition of the JAK-STAT pathway. Incyte Corporation launched a strategy to identify molecules suitable for both topical as well as oral delivery. Ruxolitinib was designed as a molecule with low nanomolar potency selective for JAK1 and 2 enzymes, but without significant inhibition of non-JAK kinases, as well as physicochemical properties for both topical and oral administration. An oil-in-water emulsified ruxolitinib cream formulation was developed for topical application and was studied in multiple immune-mediated dermatologic diseases including psoriasis, alopecia areata, atopic dermatitis and vitiligo. Ruxolitinib cream represents a novel, JAK1/2 selective therapy that can be delivered directly to the skin to treat a number of cytokine-driven, inflammatory dermatoses.

Transverse Needling After Autologous Mini-Punch Grafts Improves Repigmentation in Stable Non-Segmental Vitiligo

Background

Repigmentation remains the primary target in vitiligo treatment. Melanocyte transfer procedures are often required for repigmenting stable, resistant vitiligo lesions necessitating procedural optimization and comparative evaluation. In the current study, we aimed to assess the additive value of weekly transverse needling sessions after mini-punch grafting for repigmenting stable non-segmental vitiligo lesions versus either procedure alone.

Methods

Eighty lesions, included in 20 stable non-segmental vitiligo patients, were randomly allocated to each of the three treatment groups (line-1, mini-punch grafting; line-2, needling; and line-3, combined grafting and needling) and to a fourth control group receiving non-procedural treatment (line-4). Oral mini-pulse steroids and narrow-band ultraviolet-B sessions were administered to all patients for 3 months before and 6 months after the interventions. The extent of repigmentation was assessed using planimetry. Secondary outcomes were the time to first repigmentation response, cosmetic matching, and patient satisfaction. Blinding and allocation concealment were not feasible owing to the intervention nature and within subject design.

Results

Mini-punch grafting followed by weekly needling for 6 months achieved the fastest response and highest extent of repigmentation. Mini-punch grafts and transverse needling alone provided better results than the control group. No steroid-associated side effects were reported.

Conclusion

Weekly needling sessions after mini-punch grafting hastened and improved the repigmentation extent of stable, resistant, non-segmental vitiligo lesions and should be considered during treatment planning.

A20 deficiency in myeloid cells deteriorates the onset of vitiligo in mice

Melanocyte-specific CD8⁺ T cells enrichment correlates with the severity of vitiligo, and the role of A20 derived from myeloid cells in the enrichment of pathogenic T cells is unknown. Premelanosome (PMEL)-specific transgenic CD8⁺ T cells were adoptive transferred into Krt14-Kitl* mice to construct the vitiligo model, which was further mated with A20^MKO mice and IKK2^fl/fl mice. Bone marrow cells were stimulated with 30% L929 cell-conditioned medium, Fc-human tumor necrosis factor, and lipopolysaccharides to induce bone marrow-derived macrophages (BMDMs). The relative expression of CCL2, CCL5, and IL12A was detected with real-time PCR, and nuclear factor kappa B (NFκB) related molecules were detected with Western blots. Fluorescence-activated cell sorting (FACS) was utilized to assay the percent of innate and adaptive immune cells in the spleen and bone marrow, and CD45⁺ T in the skin. Down-regulated A20 was detected in the skin biopsies of vitiligo patients. A20 deficiency did not affect the development of T cells, B cells, macrophages, and neutrophils. A20 negatively regulated the induction of proinflammatory chemokines (CCL2, CCL5, and IL12A) and NFκB-related molecule expression in BMDMs, which could be blocked by NFκB knockout. It further revealed that A20 negatively regulated the onset of vitiligo in mice with diminished CD45⁺ cells enrichment, which could also be reversed by NFκB knockout. A20 deficiency in myeloid cells could deteriorate the onset of vitiligo in mice, and A20 can be considered as a treatment target.

Transcriptome and Differential Methylation Integration Analysis Identified Important Differential Methylation Annotation Genes and Functional Epigenetic Modules Related to Vitiligo

Vitiligo is an pigmentation disorder caused by a variety of pathogenic factors; its main pathophysiological conditions include oxidative stress, immune activation, and genetic background. Additionally, DNA methylation is often associated with the pathogenesis of vitiligo; however, the underlying mechanism remains unknown. In the present study, we used the Human Methylation 850K BeadChip platform to detect DNA methylation changes in the vitiligo melanocytes. We then integrated the results with the transcriptome data of vitiligo melanocytes and lesions to analyse the correlation between differentially methylated levels and differentially expressed genes. The results showed that there was a significant negative correlation between methylation levels and differentially expressed genes. Subsequently, we enriched GO and KEGG based on methylated differentially expressed genes (MDEGs) using R package ClusterProfiler, and the results were closely related to the pathogenesis of vitiligo. In addition, we also constructed a PPI network of MDEGs and excavated three important functional epigenetic modules, involving a total of 12 (BCL2L1, CDK1, ECT2, HELLS, HSP90AA1, KIF23, MC1R, MLANA, PBK, PTGS2, SOX10, and TYRP1) genes. These genes affect melanocyte melanogenesis, cellular oxidative stress and other important biological processes. Our comprehensive analysis results support the significant contribution of the status of DNA methylation modification to vitiligo, which will help us to better understand the molecular mechanism of vitiligo and explore new therapeutic strategies.

Vitiligo: An Updated Narrative Review

BACKGROUND

Vitiligo is a relatively common acquired pigmentation disorder that can cause significant psychological stress and stigmatism.

OBJECTIVE

This article aims to familiarize physicians with the clinical manifestations, evaluation, diagnosis, and management of vitiligo.

METHODS

A Pubmed search was conducted in Clinical Queries using the key term "vitiligo". The search included meta-analyses, randomized controlled trials, clinical trials, observational studies, and reviews. The search was restricted to English language. The information retrieved from the above search was used in the compilation of the present article.

RESULTS

Approximately one quarter of patients with vitiligo have the onset before 10 years of age. Genetic, immunological, neurogenic and environmental factors may have a role to play in the pathogenesis. Vitiligo typically presents as acquired depigmented, well-demarcated macules/patches that appear milk- or chalk-white in color. Lesions tend to increase in number and enlarge centrifugally in size with time. Sites of predilection include the face, followed by the neck, lower limbs, trunk, and upper limbs. The clinical course is generally unpredictable. In children with fair skin, no active treatment is usually necessary other than the use of sunscreens and camouflage cosmetics. If treatment is preferred for cosmesis, topical corticosteroids, topical calcineurin inhibitors, and narrowband ultraviolet B phototherapy are the mainstays of treatment.

CONCLUSION

The therapeutic effect of all the treatment modalities varies considerably from individual to individual. As such, treatment must be individualized. In general, the best treatment response is seen in younger patients, recent disease onset, darker skin types, and head and neck lesions. Topical corticosteroids and calcineurin inhibitors are the treatment choice for those with localized disease. Topical calcineurin inhibitors are generally preferred for lesions on genitalia, intertriginous areas, face, and neck. Narrowband ultraviolet B phototherapy should be considered in patients who have widespread vitiligo or those with localized vitiligo associated with a significant impact on the quality of life who do not respond to treatment with topical corticosteroids and calcineurin inhibitors.

Pathogenesis of vitiligo

Vitiligo is an autoimmune disease in which CD8+ T-cells target and destroy melanocytes, leaving areas of skin without pigment production. Nonsegmental vitiligo, the classical form of the disease, results in symmetrical, bilateral white patches. Vitiligo is a chronic, unpredictable disease, characterized by flares, with depigmentation and periods of disease arrest alternating. This process can be stressful and negatively impact one’s quality of life. Various hypotheses have been offered, including cellular stress causing degeneration of melanocytes, chemical toxicity causing melanocyte death, and neural changes that influence melanocytes or their ability to produce melanin. Recently, the interaction between oxidative stress and autoimmune-mediated melanocyte loss has been proposed as the primary pathogenesis of vitiligo. It is now well accepted that interferon-γ and/or C-X-C motif chemokine ligand 10 axis is functionally required for both progression and maintenance of vitiligo, making this pathway a potential therapeutic target. Most therapeutic interventions in the management of vitiligo have been developed based on this immunopathogenesis. This article aims to review the current understanding of the vitiligo pathogenesis.

HLA-A29 and Birdshot Uveitis: Further Down the Rabbit Hole

HLA class I alleles constitute established risk factors for non-infectious uveitis and preemptive genotyping of HLA class I alleles is standard practice in the diagnostic work-up. The HLA-A29 serotype is indispensable to Birdshot Uveitis (BU) and renders this enigmatic eye condition a unique model to better understand how the antigen processing and presentation machinery contributes to non-infectious uveitis or chronic inflammatory conditions in general. This review will discuss salient points regarding the protein structure of HLA-A29 and how key amino acid positions impact the peptide binding preference and interaction with T cells. We discuss to what extent the risk genes ERAP1 and ERAP2 uniquely affect HLA-A29 and how the discovery of a HLA-A29-specific submotif may impact autoantigen discovery. We further provide a compelling argument to solve the long-standing question why BU only affects HLA-A29-positive individuals from Western-European ancestry by exploiting data from the 1000 Genomes Project. We combine novel insights from structural and immunopeptidomic studies and discuss the functional implications of genetic associations across the HLA class I antigen presentation pathway to refine the etiological basis of Birdshot Uveitis.

Vitiligo, From Physiopathology to Emerging Treatments: A Review

Vitiligo is a chronic inflammatory skin disease leading to the loss of epidermal melanocytes. To date, treatment options for vitiligo patients are limited, lack sustained efficacy, and are mainly based on off-label use of immunosuppressive agents, such as systemic or topical steroids or topical calcineurin inhibitors, in association with the use of ultraviolet light. However, recent insights into the understanding of the immune pathogenesis of the disease have led to the identification of several therapeutic targets and the development of targeted therapies that are now being tested in clinical trials. In this review, based on the physiopathology of the disease, we summarize emerging targets that could be developed for the treatment of vitiligo and discuss recent and ongoing developments of drugs for the management of the disease.