Translational Research in Vitiligo

Low-Dose Baricitinib Plus Narrow-Band Ultraviolet B for the Treatment of Progressive Non-Segmental Vitiligo: A Prospective, Controlled, Open-Label Study

Vitiligo is a chronic autoimmune disease, and current treatments for vitiligo have limited efficacy. Janus kinase (JAK) inhibitors could offer new therapeutic options. To evaluate the efficacy and safety of baricitinib, an oral JAK1/2 inhibitor, combined with narrow-band ultraviolet B (NB-UVB) in vitiligo treatment. This prospective, controlled, open-label study included adults with progressive non-segmental vitiligo (NSV). Patients were assigned to combination therapy with baricitinib 2 mg daily and NB-UVB three times a week or NB-UVB alone three times a week (control). The primary endpoint was the proportion of patients achieving 50% or greater improvement from baseline in the total Vitiligo Area Scoring Index (T-VASI50) at week 16. Of the 33 patients (mean age, 34.1 years; 27.3% women) who completed the study, 12 of 17 (70.6%) patients in the combination group and 2 of 16 (12.5%) in the control group had a T-VASI50 response at week 16 (relative risk [RR] = 5.6; 95% CI = 1.5-21.4; p = 0.001). Adverse events were minor, including erythema, mild blister after phototherapy and acne. Combination therapy with low-dose baricitinib and NB-UVB was effective and well tolerated in adults with progressive NSV.

Segmental vitiligo: autoimmune pathogenesis, neuronal mechanisms, and somatic mosaicism

Vitiligo is a common depigmentation disorder classified into nonsegmental vitiligo (NSV) and segmental vitiligo (SV). SV accounts for 5-27.9% of patients with vitiligo. The primary pathogenesis of NSV involves the autoimmune-mediated destruction of melanocytes. Recently, an autoimmune pathogenesis of SV was identified. High levels of melanocyte antigen-specific CD8+ T cells are found in early SV lesional skin infiltrating around melanocytes along the basal layer. Mixed vitiligo suggests an overlap in pathogenesis between SV and NSV. In active SV, serum innate immune cytokines, and CD8+ T cell cytokines are increased. Oxidative stress in SV may activate autoimmune responses. SV pathogenesis is associated with a local cytotoxic response targeting epidermal melanocytes. Theories have been put forward to explain the segmental pattern in SV. The previous basis of the neurogenic theory that SV results from dermatomes is no longer accepted. However, there are still research reports supporting this theory. Evaluating the distribution pattern of SV lesions has provided clues to the mosaicism detection of suspected melanocytic defects at the site of SV lesions, supporting this theory. Evidence points to a cytotoxic response targeting mosaic melanocytes. Understanding SV's autoimmune pathogenesis prompts a reevaluation of immunosuppressive medical treatments for SV. The excellent results of autologous melanocyte transplantation in SV lesions compared with the moderate to limited results in patients with NSV support the mosaicism theory.

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.

In-silico evaluation of phytochemicals for vitiligo: ADMET, molecular docking, and MD simulation approaches

Vitiligo is a prevalent autoimmune disease affecting the quality of life and self-confidence. Total 25 phytochemicals from plants were screened by using four target proteins involved in the pathogenesis of vitiligo. The binding affinity of the ligands ranged between -10.3 and -4.5 kcal/mol. The top 10 phytochemicals i.e. rosmarinic acid, piperine, tamarixetin, desmethoxycurcumin, bisdemethoxycurcumin, isorhamnetin, quercetin, vicenin II, genkwanin, and aloe-emodin showed good inhibition with binding affinity ranged from -10.3 to 9.4 Kcal. The ADMET profiling revealed that these phytochemicals might be safe for the treatment of vitiligo. In MD simulation, rosmarinic acid, piperine, and tamarixetin with MAO-A formed stable complexes and the free binding energies of the complexes were -34.02 ± 6.94, -33.51 ± 2.65, and -27.17 ± 3.28. Furthermore, the ligands formed hydrogen bonds with targets, suggested that rosmarinic acid, piperine, and tamarixetin have potential to serve as lead compounds for developing novel therapeutics for vitiligo after in vitro and in vivo studies.

Disorganisation of basement membrane zone architecture impairs melanocyte residence in vitiligo

The basement membrane zone is the interface between the epidermis and dermis, and it is disrupted in several skin conditions. Here, we report the results of a comprehensive investigation into the structural and molecular factors of the basement membrane zone in vitiligo, a dermatological disorder characterised by depigmented patches on the skin. Using electron microscopy and immunofluorescence staining, we confirmed abnormal basement membrane zone morphology and disrupted basement membrane zone architecture in human vitiliginous skin. Furthermore, we identified elevated expression of matrix metalloproteinase 2 (MMP2) in human dermal fibroblasts as a key factor responsible for basement membrane zone matrix degradation. In our in vitro and ex vivo models, overexpression of MMP2 in fibroblasts led to basement membrane zone disruption and melanocyte disappearance. Importantly, we reveal that the loss of melanocytes in vitiligo is primarily linked to their weakened adhesion to the basement membrane, mediated by binding between integrin β1 and laminin and discoidin domain receptor 1 and collagen IV. Finally, inhibition of matrix metalloproteinase 2 expression reversed depigmentation in a mouse model of vitiligo. In conclusion, our research shows the importance of basement membrane zone integrity in melanocyte residence and offers new avenues for therapeutic interventions to address this challenging skin condition. © 2024 The Author(s). The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Establishment of a promising vitiligo mouse model for pathogenesis and treatment studies

AIMS

Vitiligo is a chronic dermatological condition characterized by the progressive loss of melanocytes, for which traditional therapy has shown limited efficacy. This study aimed to establish a vitiligo model with easy operability, high repeatability, and stable depigmentation to provide a foundation for studying the pathogenesis and developing novel therapies for vitiligo.

METHODS

(1) Establishing vitiligo model: Firstly, deliver B16F10 cells to the back skin of C57BL/6 J via intradermal injection (day 0), and the CD4 depletion antibody was injected intraperitoneally on day 4 and 10. Secondly, the melanoma was surgically removed on day 12. Thirdly, CD8 antibody was administered intraperitoneally every fourth day till day 30. (2) Identification of vitiligo model: H&E staining, immunohistochemistry, and immunofluorescence were used to detect the melanocytes. The melanin was detected by transmission electron microscopy (TEM), Lillie ferrous sulfate staining and L-DOPA staining.

RESULTS

(1) The back skin and hair began to appear white on day 30. Melanin loss reached peak on day 60; (2) Hematoxylin and eosin (H&E) staining, immunohistochemistry and immunofluorescence results showed melanocytes were reduced. L-DOPA staining, Lillie ferrous sulfate staining and TEM results showed that melanin decreased in the epidermis.

CONCLUSION

We successfully establishment a vitiligo mouse model which can be more capable to simulate the pathogenesis of human vitiligo and provide an important basis for the study of pathogenesis and therapy of vitiligo.

Performing Suction Blister Skin Biopsies

Traditional skin sampling methods include punch or shave biopsies to produce a solid tissue sample for analysis. These biopsy procedures are painful, require anesthesia, and leave permanent scars. This unit describes a suction blister skin biopsy method that can be used in place of traditional biopsy methodologies as a minimally invasive, non-scarring skin sampling technique. The induction of suction blisters uses an instrument with a chamber that applies negative pressure and gentle heat to the skin. Blister formation occurs within 1 hr, producing up to five blisters, each 10 mm in diameter per biopsy site. Blister fluid can be extracted and centrifuged to retrieve cells from the epidermis and upper dermis for flow cytometry, single-cell RNA sequencing, cell culture, and more without the need for digestion protocols. In addition, the blister fluid can be used to measure soluble proteins and metabolites. This unit describes the preparation of supplies and subjects, the suction blister biopsy procedure and blister formation, fluid extraction, and post-blistering care. © 2024 Wiley Periodicals LLC. Basic Protocol 1: Preparation of supplies and subject Basic Protocol 2: Suction blister biopsy procedure and formation Basic Protocol 3: Blister fluid extraction Basic Protocol 4: Post-blister care and clean up.

Pathogenesis of Alopecia Areata and Vitiligo: Commonalities and Differences

Both alopecia areata (AA) and vitiligo are distinct, heterogenous, and complex disease entities, characterized by nonscarring scalp terminal hair loss and skin pigment loss, respectively. In AA, inflammatory cell infiltrates are in the deep reticular dermis close to the hair bulb (swarm of bees), whereas in vitiligo the inflammatory infiltrates are in the epidermis and papillary dermis. Immune privilege collapse has been extensively investigated in AA pathogenesis, including the suppression of immunomodulatory factors (e.g., transforming growth factor-β (TGF-β), programmed death-ligand 1 (PDL1), interleukin-10 (IL-10), α-melanocyte-stimulating hormone (α-MSH), and macrophage migration inhibitory factor (MIF)) and enhanced expression of the major histocompatibility complex (MHC) throughout hair follicles. However, immune privilege collapse in vitiligo remains less explored. Both AA and vitiligo are autoimmune diseases that share commonalities in pathogenesis, including the involvement of plasmacytoid dendritic cells (and interferon-α (IFN- α) signaling pathways) and cytotoxic CD8+ T lymphocytes (and activated IFN-γ signaling pathways). Blood chemokine C-X-C motif ligand 9 (CXCL9) and CXCL10 are elevated in both diseases. Common factors that contribute to AA and vitiligo include oxidative stress, autophagy, type 2 cytokines, and the Wnt/β-catenin pathway (e.g., dickkopf 1 (DKK1)). Here, we summarize the commonalities and differences between AA and vitiligo, focusing on their pathogenesis.

Management of the refractory vitiligo patient: current therapeutic strategies and future options

Vitiligo is an autoimmune disease that leads to disfiguring depigmented lesions of skin and mucosa. Although effective treatments are available for vitiligo, there are still some patients with poor responses to conventional treatment. Refractory vitiligo lesions are mostly located on exposed sites such as acral sites and lips, leading to significant life stress. Understanding the causes of refractory vitiligo and developing targeted treatments are essential to enhance vitiligo outcomes. In this review, we summarized recent treatment approaches and some potential methods for refractory vitiligo. Janus kinase inhibitors have shown efficacy in refractory vitiligo. A variety of surgical interventions and fractional carbon dioxide laser have been widely applied to combination therapies. Furthermore, melanocyte regeneration and activation therapies are potentially effective strategies. Patients with refractory vitiligo should be referred to psychological monitoring and interventions to reduce the potential pathogenic effects of chronic stress. Finally, methods for depigmentation and camouflage may be beneficial in achieving uniform skin color and improved quality of life. Our ultimate focus is to provide alternative options for refractory vitiligo and to bring inspiration to future research.

Circulating Podocalyxin, Tumstatin/Col-IVα3 and Chitinase 1: New Culprits in Vitiligo Occurrence

INTRODUCTION

The roles of anti-adhesive podocalyxin (PODXL), anti-angiogenetic tumstatin/ Col-IVα3 and neuro-inflammation and innate immunity modulator Chitinase 1 (CHIT-1) in the etiology of vitiligo have not been studied yet.

OBJECTIVES

This study was planned to detect changes in serum PODXL, tumstatin/Col-IVα3 and CHIT1 levels in vitiligo patients.

METHODS

This case-controlled study was performed on a total of 50 patients, 25 with vitiligo and 25 healthy controls. Participants in the vitiligo and control groups were matched in pairs for age and sex. At least 8-10 hours of overnight fasting, venous blood samples were taken from the participants in both groups and serum levels of podocalyxin, tumstatin/Col-IVα3 and CHIT 1 levels were measured by sandwich enzyme immunoassay.

RESULTS

In the classification made according to the vitiligo European Task Force evaluation criteria, 18 of 25 vitiligo patients were in the slowly progressive phase and 7 patients were in the active progressive phase. Serum podocalyxin levels increased significantly in the vitiligo group compared to the controls (7.03±2.09 ng/ml vs. 4.99±1.20 ng/ml, p<0.02). However, serum tumstatin levels in vitiligo patients showed a significantly lower course compared to controls (4.88±1.76 ng/ml vs. 6.05±2.19 ng/nl, p<0.03). Serum CHIT-1 levels of vitiligo patients (42.4±7.22 ng/ml) were found to be significantly higher than the serum levels of the control group (34.5±5.33 ng/ml) (p<0.01).

CONCLUSION

High podocalyxin and CHIT1versus low tumstatin levels are new biomarkers that support the role of anti-adhesive, anti-angiogenic and neuroinflammatory pathways in the formation of vitiligo.

Vitiligo: Pathogenesis and New and Emerging Treatments

Vitiligo is a complex disease with a multifactorial nature and a high impact on the quality of life of patients. Although there are multiple therapeutic alternatives, there is currently no fully effective treatment for this disease. In the current era, multiple drugs are being developed for the treatment of autoimmune diseases. This review assesses the available evidence on the pathogenesis of vitiligo, and a comprehensive review of treatments available for vitiligo now and in the near future is provided. This qualitative analysis spans 116 articles. We reviewed the mechanism of action, efficacy and safety data of phototherapy, afamelanotide, cyclosporine, phosphodiesterase 4 inhibitors, trichloroacetic acid, basic fibroblast growth factor, tumor necrosis factor (TNF) inhibitors, secukinumab, pseudocatalase and janus kinase (JAK) inhibitors. At the moment, there is no clearly outstanding option or fully satisfactory treatment for vitiligo, so it is necessary to keep up the development of new drugs as well as the publication of long-term effectiveness and safety data for existing treatments.

Mitochondria-Melanocyte cellular interactions: An emerging mechanism of vitiligo pathogenesis

Mitochondria has emerged as a potential modulator of melanocyte function other than just meeting its cellular ATP demands. Mitochondrial DNA defects are now an established cause of maternal inheritance diseases. Recent cellular studies have highlighted the mitochondrial interaction with other cellular organelles that lead to disease conditions such as in Duchenne muscular dystrophy, where defective mitochondria was found in melanocytes of these patients. Vitiligo, a depigmentory ailment of the skin, is another such disorder whose pathogenesis is now found to be associated with mitochondria. The complete absence of melanocytes at the lesioned site in vitiligo is a fact; however, the precise mechanism of this destruction is still undefined. In this review we have tried to discuss and link the emerging facts of mitochondrial function or its inter- and intra-organellar communications in vitiligo pathogenesis. Mitochondrial close association with melanosomes, molecular involvement in melanocyte-keratinocyte communication and melanocyte survival are new paradigm of melanogenesis that could ultimately account for vitiligo. This definitely adds the new dimensions to our understanding of vitiligo, its management and designing of future mitochondrial targeted therapy for vitiligo.

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.

Vitiligo and insulin resistance as a component of metabolic syndrome: an analysis

There have been many studies on the association between vitiligo and metabolic syndrome, while only few scientific papers on vitiligo and insulin resistance. In recent years, there have been significant developments in research to trace and understand the aetiology of both conditions. In this article we have analysed pathophysiological mechanisms and the association of insulin resistance (as a component of metabolic syndrome) and vitiligo.

How Does Vitamin D Affect Immune Cells Crosstalk in Autoimmune Diseases?

Vitamin D is a secosteroid hormone that is highly involved in bone health. Mounting evidence revealed that, in addition to the regulation of mineral metabolism, vitamin D is implicated in cell proliferation and differentiation, vascular and muscular functions, and metabolic health. Since the discovery of vitamin D receptors in T cells, local production of active vitamin D was demonstrated in most immune cells, addressing the interest in the clinical implications of vitamin D status in immune surveillance against infections and autoimmune/inflammatory diseases. T cells, together with B cells, are seen as the main immune cells involved in autoimmune diseases; however, growing interest is currently focused on immune cells of the innate compartment, such as monocytes, macrophages, dendritic cells, and natural killer cells in the initiation phases of autoimmunity. Here we reviewed recent advances in the onset and regulation of Graves' and Hashimoto's thyroiditis, vitiligo, and multiple sclerosis in relation to the role of innate immune cells and their crosstalk with vitamin D and acquired immune cells.

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.

Beyond skin white spots: Vitiligo and associated comorbidities

Vitiligo is a common depigmentation disorder of an unknown origin characterized by the selective loss of melanocytes, resulting in typical white macules and patches. However, vitiligo is now recognized as more than just a skin disease, what a dermatologist observes as a white spot of skin is just the "tip of the iceberg" of the condition. We attempt to clarify the classification of comorbidities associated with vitiligo from various reviews and reports, and describe their possible pathogenesis. In conclusion, the literature provides evidence of an association between vitiligo and ocular and auditory abnormalities, autoimmune disorders, other dermatological diseases, metabolic syndrome and related disorders, and psychological diseases. These associations highlight the importance of a multidisciplinary approach in managing vitiligo patients.

A comprehensive meta-analysis and prioritization study to identify vitiligo associated coding and non-coding SNV candidates using web-based bioinformatics tools

Vitiligo is a prevalent depigmentation disorder affecting around 1% of the general population. So far, various Genome Wide Association Studies (GWAS) and Candidate Gene Association Studies (CGAS) have identified several single nucleotide variants (SNVs) as a risk factor for vitiligo. Nonetheless, little has been discerned regarding their direct functional significance to the disease pathogenesis. In this study, we did extensive data mining and downstream analysis using several experimentally validated datasets like GTEx Portal and web tools like rSNPBase, RegulomeDB, HaploReg and STRING to prioritize 13 SNVs from a set of 291SNVs that have been previously reported to be associated with vitiligo. We also prioritized their underlying/target genes and tried annotating their functional contribution to vitiligo pathogenesis. Our analysis revealed genes like FGFR10P, SUOX, CDK5RAP1 and RERE that have never been implicated in vitiligo previously to have strong potentials to contribute to the disease pathogenesis. The study is the first of its kind to prioritize and functionally annotate vitiligo-associated GWAS and CGAS SNVs and their underlying/target genes, based on functional data available in the public domain database.

The potential effect of smart devices and other stressful factors on Vitiligo in Nassiriah City/Iraq

BACKGROUND

Vitiligo is a disease that occurs due to dysfunction in the autoimmune system that attacks the skin pigment cells (melanocytes) leading to the appearance of light-colored spots on the skin.

OBJECTIVE

The study was carried out to investigate the effect of smart devices on the children inflicted with vitiligo, and the correlation of vitiligo with other factors such as performance in the school, the marital status of their parents, type of smart devices (games, YouTube), and others.

MATERIALS AND METHODS

The study was carried out on 49 children diagnosed with vitiligo in Nassiriah City, Iraq. The data of all the variable factors were collected and classified according to the types of smart applications (YouTube and/or games), the status of their parents, and hours spent on using these applications.

RESULTS

The collected data were analyzed into five figures; according to the children's performance in the school and the highest percentage were in the no failure category, or in the high achiever category constituting 38.77% to each one. The percentage of children who lives with both parents is 79.5%. Most of the affected children are the 2nd in order in their families representing 40.8% of children under study. The number of diseased children who use YouTube are 23, their percentage is the highest constituting 46.94%.

CONCLUSIONS

Seven conclusions were drawn in this novel study, among them are; that most of the affected children are 2nd in order in their families, and the highest percent of the affected children with vitiligo are those who use YouTube.

Efficacy of local prostaglandin analogues for vitiligo treatment: a systematic review and meta-analysis

BACKGROUND

Vitiligo is a common cutaneous depigmentation disorder. Although multiple treatment options are available, no single modality is satisfactory for all patients. Several studies have demonstrated that prostaglandin analogues can potentially treat cutaneous depigmentation, but the evidence is limited to their inconsistent study design.

RESEARCH DESIGN & METHODS

A systematic review was performed for studies published before 29 June 2021, in PubMed, Embase, Web of Science, or the Cochrane Library. The primary outcome of pooled analysis was the repigmentation efficacy of local prostaglandin analogues compared with other therapies for vitiligo.

RESULTS

Six randomized controlled trials (RCTs) and three non-RCTs were included in this systematic review, and seven studies among them were used for the meta-analysis. The pooled analysis demonstrated that local prostaglandin analogues could significantly increase repigmentation along with narrowband ultraviolet B phototherapy compared with phototherapy alone. Furthermore, the repigmentation efficacy of topical prostaglandin analogues was not significantly different from that of topical tacrolimus. In summary, local prostaglandin analogues either used alone or as add-on therapy could be safe and effective therapies for vitiligo.

Occludin Promotes Adhesion of CD8+ T Cells and Melanocytes in Vitiligo via the HIF-1α Signaling Pathway

Loss of melanocytes induced by activated CD8+ T cells is the pathological hallmark of vitiligo. Melanocyte-specific CD8+ T cells are recruited to the skin via chemokines, thereby releasing perforin, granzyme, and other cytotoxic substances that destroy the melanocytes. However, the mechanism of CD8+ T cells to adhere to melanocytes is unknown. Previous transcriptome sequencing results published by our group showed that the occluding (OCLN) gene was significantly upregulated in CD8+ T cells from skin lesions of vitiligo. Occludin is a crucial component of the tight junction between cells; in cells without tight junction, occludin mediates the adhesion of two cells in the form of a self-ligand. This study demonstrated that OCLN gene expression was elevated in the CD8+ T cells of vitiligo patients, and occludin mediates the adherence of CD8+ T cells to melanocytes. Besides, pathological changes in vitiligo skin lesions reveal that CD8+ T cells continuously persist in the skin lesions, which is related to the persistence of the disease. In this regard, we found that fibroblasts from vitiligo patients significantly express occludin, which may participate in the continuous retention of CD8+ T cells in the skin lesions. The pathogenesis of vitiligo is closely related to oxidative stress, and our data suggest that overexpression of hypoxia-inducible factor-1α (HIF-1α) increases the expression of occludin. Besides, ChIP-qPCR of CD8+ T cells revealed that HIF-1α directly binds to the OCLN promoter. Thus, occludin upregulation promotes the adhesion of CD8+ T cells and melanocytes via the HIF-1α signaling pathway. Our study results suggested a critical role for OCLN in the occurrence, progression, and maintenance of vitiligo. Therefore, inhibiting the expression of OCLN gene may be a potential targeted treatment strategy.

Morphological Alterations and Increased S100B Expression in Epidermal Langerhans Cells Detected in Skin from Patients with Progressive Vitiligo

The role of Langerhans cells (LCs) in vitiligo pathogenesis remains unclear, with published studies reporting contradictory results regarding the quantity of LCs and no data on the features of LCs in vitiligo. Here, we aimed to analyze the presence, density, and morphological features of LCs in the epidermis of patients with vitiligo. Skin biopsies were stained for LCs using anti-CD1a/anti-langerin antibodies and analyzed by immunocytochemistry with light and electron microscopy. Compared with healthy controls, we detected significantly increased numbers of epidermal LCs in lesional skin from vitiligo in the progressive state. These LCs exhibited striking morphological alterations, including an elevated number of dendrites, with increased length and more branches than dendrites from controls. Ultrastructure examination via immuno-electron microscopy revealed markedly reduced Birbeck granules (BGs) and shorter BG rods in LCs from progressive vitiligo, with higher expression of langerin. Additionally, expression of S100B, the activity biomarker of vitiligo, was increased in these LCs. This work provides new insight on the cellular composition of LCs in vitiliginous skin, revealing altered morphology and increased LC numbers, with elevated S100B expression. Our data suggest LCs might play a critical role in vitiligo pathogenesis and thus may represent a novel therapeutic target for this disease.