Vitiligo: Translational research and effective therapeutic strategies

In vivo 3D photoacoustic and ultrasound analysis of hypopigmented skin lesions: A pilot study

Vitiligo needs early identification for proper intervention. Current adjunct diagnostic methods rely mostly on subjective visual inspection. Thus, identification of early or atypical vitiligo lesions among other hypopigmentation disorders may pose challenges. To overcome this, we investigate the feasibility of a three-dimensional (3D) photoacoustic (PA) and ultrasound (US) imaging technique as a new adjuvant analytic tool providing quantitative characterization of hypopigmentation features. This cross-sectional study was conducted at Seoul St. Mary's Hospital (Seoul, Republic of Korea) between August 2022 and January 2024. Lesions diagnosed vitiligo or IGH in locations that could safely be irradiated with laser were analyzed with 3D PA/US imaging along with the conventional diagnostic methods. A total of 53 lesions consisted of 36 vitiligo lesions and 17 IGH lesions from 39 participants with confirmed diagnosis were analyzed. The PA amplitude greatly differed between normal skin and hypopigmentation lesions, and the mean PA amplitudes of vitiligo lesions were slightly higher than that of IGH [mean (standard deviation, SD): vitiligo: 0.117 (0.043); IGH: 0.135 (0.028)]. The local SD of the PA amplitude were higher in IGH than in vitiligo lesions [vitiligo: 0.043 (0.018); IGH: 0.067 (0.017)]. The mean PA slope across the lesion boundary was significantly higher in IGH than in vitiligo [vitiligo: 0.173 (0.061); IGH: 0.342 (0.099)], whereas the PA peak depth was deeper in vitiligo than in IGH [vitiligo: 0.568 (0.262); IGH: 0.266 (0.116)]. Unlike conventional qualitative methods, 3D PA/US imaging can non-invasively provide quantitative metrics which might aid in the differentiation of vitiligo from IGH lesions.

Knowledge and attitudes towards vitiligo in egyptian and palestinian communities: a cross-sectional study

BACKGROUND

Vitiligo is an acquired dermatological condition characterized by localized skin depigmentation. It affects 0.5% to 2% of the population, impacting individuals across various ages, races, and genders. The psychosocial effects of Vitiligo can significantly influence quality of life, particularly in people with darker skin tones, where the contrast of lesions is more pronounced.

OBJECTIVES

This study evaluated public knowledge, attitudes, and misconceptions regarding Vitiligo in Egypt and Palestine, focusing on specific demographic Variations and the potential need for improved community engagement and education.

METHOD

A multicenter cross-sectional study was conducted involving 1,045 participants from Egypt and 450 participants from the West Bank. An online self-administered questionnaire was developed using Google Forms. The eligibility criteria for participation included Egyptian and Palestinian citizens residing in the West Bank. Individuals under 18 years or outside the designated study settings were excluded from participation. This study was conducted from April 2024 to August 2024.

RESULTS

The analysis indicated that 62.8% of participants demonstrated adequate knowledge of Vitiligo; however, only 87.6% exhibited favorable attitudes toward the condition. The study revealed significant variations in knowledge and attitudes based on gender, occupation, previous health professional experience, and social status. Economic level and geographic location. Educational level was found to have a considerable impact on attitudes. Multiple linear regression analysis identified several significant predictors of. Knowledge and attitude scores included male gender, age categories of 18 to 25 and over 50, marital status, occupation in a health profession, personal experience with Vitiligo, prior awareness of the condition, and the attitude score itself. This explained 30.2% of the variance in knowledge scores and 28.1% in attitude ratings.fig.

CONCLUSION

This study provides valuable insights into public awareness and perceptions of Vitiligo in Egypt and Palestine. A significant proportion of the participants demonstrated adequate awareness of the condition; however, favorable opinions appeared less prevalent. Notable discrepancies were observed among the various demographic characteristics, highlighting the need for targeted initiatives, such as media campaigns and school-based education, aimed at addressing information gaps and improving public perception.

Development of a Digital Image-Based Method to Screen Molecules That Regulate Melanization

Vitiligo vulgaris is an acquired disorder that is thought to arise from the suppression of melanin synthesis by melanocytes in the basal epidermal layer. To develop therapeutic agents for vitiligo vulgaris, it is critical to identify compounds that promote melanization. In this study, we established a digital image-based method to quantify melanization that does not require biochemical procedures. B16F10 cells were seeded in a white-bottom 96-well microplate. After treatment with or without α-melanocyte-stimulating hormone, followed by fixation of the cells, digital images of the microplates were captured, and the total signal intensity of each well on the image was measured. The extent of melanization in the cells in each well was defined after the subtraction of the signal from the corresponding blank well. This method was found to quantify melanization more sensitively than the conventional technique that measures the absorbance of cell lysates at UV-A wavelengths. We obtained statistical parameters showing that this method was applicable to a high-throughput screening assay; thus, this method appears to be useful for screening and identifying molecules that suppress or promote melanization, the latter of which may be developed as therapeutic agents for vitiligo vulgaris.

Increased splicing of CXCR3 isoform B (CXCR3B) by impaired NRF2 signaling leads to melanocyte apoptosis in active vitiligo

Apoptotic melanocytes (MCs) may release neoantigenic epitopes preceding epidermal infiltration by autoreactive CD8+ T cells in early vitiligo. However, the mechanism by which vitiligo MCs are prone to apoptosis under oxidative stress remains elusive. Pro-apoptotic receptor C-X-C motif chemokine receptor 3 isoform B (CXCR3B) is critical for inducing MC apoptosis in the inflammatory microenvironment of lesional vitiligo skin. Here, we show that C-X-C motif chemokine ligand 10 (CXCL10), a functional ligand for CXCR3B, is upregulated in primary dermal fibroblasts and in CD90+ reticular fibroblasts of vitiligo skin. The number of CXCR3B+ MCs was increased in active vitiligo skin compared with healthy skin and stable vitiligo skin. Mechanistically, impaired nuclear factor erythroid 2-related factor 2 (NRF2) signaling in oxidatively stressed MCs leads to the elevated expression of CXCR3B and increased apoptosis. The overexpression of NRF2 prevents MCs from CXCL10-induced apoptosis through upregulation of pro-survival receptor CXCR3 isoform A (CXCR3A). Overall, MCs expressing CXCR3B are more susceptible to apoptosis. Suppressing CXCR3B could be a promising therapeutic approach to extinguish inflammation in vitiligo skin.

Exploration of the mechanism of Qinglongyi-Buguzhi drug pair in treating vitiligo based on network pharmacology, molecular docking and experimental verification

ETHNOPHARMACOLOGICAL RELEVANCE

The Qinglongyi-Buguzhi herbal pair (QB) is one of commonly used herbal combinations for treating vitiligo in traditional Chinese medicine, consisting of the exocarp of the immature fruit of Juglans regia L. or Juglans mandshurica Maxim., and dried, mature fruit of Psoralea corylifolia L. However, the active components and potential mechanisms of QB in the treatment of vitiligo are still unclear.

AIM OF THE STUDY

The purpose of this study is to clarify the effects and mechanisms of QB on vitiligo treatment through integration of network pharmacology and empirical examinations.

MATERIALS AND METHODS

The active components and targets of QB as well as the targets linked to vitiligo were obtained from network databases. Visualization networks were constructed with Cytoscape 3.9.1. GO and KEGG enrichment analysis were conducted to investigate the possible mechanism. Molecular docking was employed to evaluate the binding affinities between the primary active ingredients of QB and essential targets of the PI3K/Akt/Nrf2 pathway. In vivo and in vitro experiments were carried out to confirm the results of network pharmacology.

RESULTS

We evaluated 44 active compounds and 602 genes from QB, and 107 of these genes linked to vitiligo. GO analysis suggested QB might lessen vitiligo by regulating oxidative stress. KEGG pathway analysis indicated the PI3K/Akt pathway may be crucial for treating vitiligo. Molecular docking results demonstrated the key active ingredients of QB had good binding activity with the major targets in the PI3K/Akt/Nrf2 pathway. In vivo, QB significantly ameliorated vitiligo model mouse's skin pathologies by reducing ROS, elevating CAT and SOD levels. Western blot showed that QB increased the phosphorylation of PI3K and Akt and the expressions of Nrf2 and HO-1 in the skin. In vitro, QB reversed H2O2-induced oxidative injury of melanocytes, enhanced cell survival rate, reduced ROS level, upregulated SOD and CAT activities, and raised the content of melanin. Moreover, QB upregulated the expression levels of Akt, Nrf2, HO-1 mRNA, Akt phosphorylation, HO-1, and nuclear Nrf2 proteins, and also encouraged the nuclear translocation of Nrf2. However, LY294002 treatment significantly reversed the regulatory effect of QB on oxidative damage of melanocytes.

CONCLUSIONS

This study revealed that the therapeutic effect of QB on vitiligo was achieved through multiple components, targets and pathways. Experimental investigation demonstrated that QB could improve vitiligo via reducing oxidative stress, which was probably accomplished by activating the PI3K/Akt/Nrf2 signaling pathway.

Dermoscopy in vitiligo, diagnostic clues and markers of disease activity: a review of the literature

Dermoscopy is a noninvasive, efficient and inexpensive tool used to aid diagnosis of skin conditions such as vitiligo. Furthermore, it aids in tracking patient progress, treatment response and disease activity. Vitiligo can be diagnosed on dermoscopy by the presence of white structureless areas signifying hypopigmentation with a typical glowing appearance. Other typical features are perilesional and perifollicular hyperpigmentation, pigmentation networks and leucotrichia. In total, 15 studies were reviewed to determine the dermoscopic signs of the three main stages of disease activity: active, stable and repigmenting vitiligo. Features that differentiate active, stable and repigmenting vitiligo are reviewed and discussed in this article. Notably, there is a conflict in the literature between various dermoscopic features and which type of vitiligo they are truly indicative of. However, dermoscopy can be coupled with other clinical, biological and physiological markers to strengthen diagnostic accuracy.

Assessment of the Quality of Life of Vitiligo Patients: A Cross-Sectional Study in the Eastern Region of Saudi Arabia

Background Vitiligo is a prevalent skin disease that results from the loss of melanocytes and subsequent hypo-melanosis, resulting in the depigmentation of the skin. It not only presents as pathological manifestations but also imposes a substantial psychological burden and exerts a significant influence on the quality of life (QOL) of individuals. This research proposal seeks to systematically explore the association between vitiligo and the QOL of affected individuals, employing rigorous scientific methodologies to identify effective interventions aimed at improving their holistic well-being. Methodology It was a cross-sectional survey conducted in the Eastern Region of the Kingdom of Saudi Arabia (KSA). Data collection utilizes an online survey through Google Forms and employs the Dermatology Life Quality Index (DLQI). Appropriate statistical analyses were performed. Results Our study comprised 263 vitiligo patients, 55.1% of whom were females and 54.4% of whom were aged 18-30. Impact assessment revealed a substantial emotional toll (56.3% embarrassed), affecting daily activities (42.6%) and clothing choices (43.7%). Notably, 36.5% reported very much impact on relationships and 35.7% on sexual problems. Notably, 41.4% face a very large impact, and 35.4% face an extremely large impact. Linear regression identified a significant gender difference (p = 0.008), with males experiencing less QOL impact or females experiencing more QOL impact due to vitiligo. Age and marital status showed nonsignificant associations. Conclusions Our study highlights the substantial impact of vitiligo on the QOL among Saudi adults. Gender significantly influences severity, with females experiencing a more severe impact on the QoL, emphasizing the need for tailored interventions and support.

Long-Term Effects and Prognosis Following Suction Blister Epidermal Grafting in Vitiligo Patients

BACKGROUND

Suction blister epidermal grafting (SBEG) is currently one of the most prevalent surgical methods for stable vitiligo.

OBJECTIVE

To investigate the long-term outcomes of vitiligo patients who underwent SBEG and to explore risk factors associated with postoperative relapse.

METHODS

A retrospective cohort study was conducted in patients who underwent SBEG in our department between January 2016 and December 2022. Treatment outcomes, including repigmentation rate, adverse events, and postoperative relapse, were surveyed via telephone interview or out-=patient visit. Multivariate logistic regression models were used to assess the potential risk factors for postoperative relapse. Statistical significance was assumed at P < .05.

RESULTS

A total of 253 patients were included with a repigmentation rate of 96% (243/253) after grafting. Common adverse events included cobblestone-like appearance (73.1%, 185/253) in the donor site, perigraft halo (46.2%, 117/253), and cobblestone-like appearance (26.1%, 66/253) in the recipient site. Postoperative relapse occurred in 20.1% of patients over a mean time of 29.7 months after grafting. Nonsegmental type of vitiligo and coexistence of autoimmune diseases were risk factors for postoperative relapse.

CONCLUSION

SBEG is an effective surgical treatment for vitiligo with high repigmentation rate and good safety profile. Nonsegmental vitiligo and comorbid autoimmune diseases may increase the risk of postoperative relapse.

The possible role of Wnt/β-catenin signalling in vitiligo treatment

Vitiligo is a common chronic skin disease which has an adverse impact on patients' life. Its pathogenesis is complex, involving autoimmunity and oxidative stress (OS). Autoimmunity leads to the loss of epidermal melanocytes and the formation of the depigmented patches of the disease. Treatment of vitiligo should control the exaggerated immune response to arrest the progress of active disease, and then promote melanocytes to repigmentation. Wnt/β-catenin signalling pathway has been of recent interest in vitiligo. Wnt/β-catenin signalling pathway is downregulated in vitiligo. Upregulation of Wnt/β-catenin signalling possibly control vitiligo autoimmune response by protecting melanocyte from OS damage, inhibiting CD8+ T cell effector cell differentiation and enhancing Treg. Wnt/β-catenin signalling plays a critical role in the melanocyte regeneration by driving the differentiation of melanocyte stem cells (McSCs) into melanocytes. Promoting Wnt/β-catenin signalling can not only arrest the progress of active disease of vitiligo but also promote repigmentation. Some of the main effective therapies for vitiligo are likely to work by activating Wnt/β-catenin signalling. Agents that can enhance the effect of Wnt/β-catenin signalling may become potential candidates for the development of new drugs for vitiligo treatment.

A randomized prospective study to assess the role of topical tacrolimus as preventive therapy in unstable acral vitiligo

BACKGROUND

Acral vitiligo is a significantly distressing condition and tends to be treatment-resistant. The occurrence of new lesions on acral areas further causes greater psychological trauma. Topical tacrolimus has been widely used in the management of vitiligo and its role in preventing flares in other dermatoses such as atopic dermatitis has been well documented.

OBJECTIVES

To assess the role of topical tacrolimus as preventive therapy in unstable acral vitiligo.

MATERIALS AND METHODS

In this single-centre randomized prospective study, 60 patients aged 16-60 years having unstable acral vitiligo with symmetrical lesions were enrolled and randomized (1:1) into two groups. Patients in group A were instructed to apply topical tacrolimus 0.1% ointment on both vitiliginous and normal skin while patients in group B were instructed to apply topical tacrolimus 0.1% ointment only on vitiliginous skin for 6 months. Only the distal hand till the wrist joint was chosen for observation. Vitiliginous patches were assessed monthly for 6 months for a change in the number of lesions and total area involved, extension of preexisting lesions and adverse effects if any.

RESULTS

A reduction in the number of lesions was observed in both groups. The decrease in the number of lesions in group A was 5.6% as compared to 2.3% in group B (p-0.001). The decrease in depigmented area in group A was 10.5% as compared to 4.6% in group B (p-0.048). Treatment failure was seen in 11 out of 60 (18.3%) patients.

CONCLUSION

Tacrolimus 0.1% ointment application showed effectiveness in preventing the appearance of new lesions in unstable acral vitiligo and hastening the repigmentation when applied on both lesional and perilesional skin in vitiligo.

Understanding of Pathomechanisms and Clinical Practice for Vitiligo

Vitiligo is a disease caused by the acquired depletion of melanocytes and/or melanocyte precursor cells in response to genetic and environmental factors, resulting in depigmentation of the entire body. It is roughly divided into segmental and non-segmental vitiligo, and it has been found that abnormalities of melanocytes themselves and dysregulation of autoimmune responses to melanocytes are greatly involved in the pathology of non-segmental vitiligo. Segmental vitiligo pathology is largely unknown; however, it has been suggested that it may be caused by skin or melanocyte mosaicism. Treatments for vitiligo include topical therapy, ultraviolet therapy, and surgical transplantation, and it is extremely important to correctly understand the pathology to perform optimal treatment. In recent years, the development of vitiligo treatments using Janus kinase (JAK) inhibitors has progressed rapidly. We herein outline the latest pathology of vitiligo, from general vitiligo treatment to the progress of clinical trials using JAK inhibitors, along with what clinicians should consider in archiving precision medicine, including my own ideas thereon.

Combining network pharmacology, molecular docking, molecular dynamics simulation, and experimental verification to examine the efficacy and immunoregulation mechanism of FHB granules on vitiligo

Background

Fufang Honghua Buji (FHB) granules, have proven efficacy against vitiligo in long-term clinical practice. However, its major active chemical components and molecular mechanisms of action remain unknown. The purpose of this study was to confirm the molecular mechanism of FHB's therapeutic effect on vitiligo utilizing network pharmacology, molecular docking, and molecular dynamics simulation prediction, as well as experimental verification.

Methods

Traditional Chinese Medicine Systems Pharmacology (TCMSP) and HERB databases were used to obtain the chemical composition and action targets of FHB. Online Mendelian Inheritance in Man (OMIM), DrugBank, DisGeNET, GeneCards, and Therapeutic Target Database (TTD) databases were applied to screen for vitiligo-related targets. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed through the Matascape database. Molecular docking and dynamics simulation methods were for the analysis of the binding sites and binding energies between the FHB's active components and the targets. Finally, a vitiligo mouse model was created, and the therapeutic effect and molecular mechanism of action of FHB were validated using enzyme linked immunosorbent assay (ELISA), western blot (WB), and quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Additionally, hematoxylin-eosin staining (HE) and blood biochemical assays were conducted to assess the biosafety of FHB.

Result

The screening of chemical composition and targets suggested that 94 genetic targets of FHB were associated with vitiligo. The bioinformatics analysis suggested that luteolin, quercetin, and wogonin may be major active components, and nuclear factor-kappa B p65 subunit (RELA), signal transducer, and activator of transcription (STAT) 3 and RAC-alpha serine/threonine-protein kinase (AKT) 1 may be potential targets of FHB-vitiligo therapy. Molecular docking and dynamics simulation further demonstrated that luteolin, quercetin, and wogonin all bound best to STAT3. Through experimental verification, FHB has been demonstrated to alleviate the pathogenic characteristics of vitiligo mice, suppress the JAK-STAT signaling pathway, reduce inflammation, and increase melanogenesis. The in vivo safety evaluation experiments also demonstrated the non-toxicity of FHB.

Conclusions

FHB exerts anti-inflammatory and melanogenesis-promoting effects via the effect of multi-component on multi-target, among which the JAK-STAT pathway is a validated FHB-vitiligo target, providing new ideas and clues for the development of vitiligo therapy.

Analysis of CD8+ TCRβ Chain repertoire in peripheral blood of vitiligo via high-throughput sequencing

Vitiligo is an autoimmune depigmentation dermatosis induced by melanocyte destruction, and CD8⁺ T cells play a pivotal role in melanocyte destruction. However, an accurate profile of the CD8⁺ T cell receptor (TCR) repertoire in vitiligo patients has not been reported, and the clonotype features of the involved CD8⁺ T cells remain largely unknown. This study aimed to assess the TCRβ chain repertoire diversity and composition of blood in nine nonsegmental vitiligo patients via high-throughput sequencing. Vitiligo patients manifested a low TCRβ repertoire diversity with highly expanded clones. Differential usage of TRBV, the TRBJ gene, and the TRBV/TRBJ combination were compared between patients with vitiligo and healthy controls. A set of TRBV/TRBJ combinations could differentiate patients with vitiligo from healthy controls (area under the curve = 0.9383, 95% CI: 0.8167-1.00). Our study revealed distinct TCRβ repertoires of CD8⁺ T cells in patients with vitiligo and will help explore novel immune biomarkers and potential therapeutic targets for vitiligo.

Management of Stable Vitiligo-A Review of the Surgical Approach

At present, vitiligo is the most common depigmenting skin disorder, characterized by clearly demarcated discolored patches of various shapes and sizes. Depigmentation results from the initial dysfunction and subsequent destruction of melanin-producing cells, called melanocytes, which are located in the basal layer of the epidermis and in hair follicles. This review concludes that the extent of repigmentation, regardless of the treatment method, is greatest in stable localized vitiligo patients. The aim of this review is to provide an overview of the clinical evidence for which the vitiligo treatment method (cellular or tissue) is more effective. The treatment relies on multiple factors, ranging from patient skin predisposition for repigmentation to the experience of the facility performing the procedure. Vitiligo is a significant problem in modern society. Although it is a typically asymptomatic and not life-threatening disease, it may have significant psychological and emotional impacts. Standard treatment relies on pharmacotherapy and phototherapy; however, the treatment of patients with stable vitiligo varies. The stability of vitiligo more than often implies the exhaustion of the potential for skin self-repigmentation. Thus, the surgical methods that distribute normal melanocytes into the skin are crucial elements of these patients' therapy. The most commonly used methods are described in the literature, with an indication of their recent progress and changes. In addition, information on the efficiency of the individual methods at specific locations is compiled in this study, and the prognostic factors indicating repigmentation are presented. Cellular methods are the best therapeutic option for large-sized lesions; although they are more exorbitant than tissue methods, they benefit from more rapid healing times and presenting fewer side effects. Dermoscopy is a valuable tool used to assess the further course of repigmentation, where it is of great value to evaluate the patient prior to and following an operation.

Acceleration of melanocyte senescence by the proinflammatory cytokines IFNγ and TNFα impairs the repigmentation response of vitiligo patients to narrowband ultraviolet B (NBUVB) phototherapy

Vitiligo is a chronic autoimmune disease characterized by the T helper 1 (Th1) cytokine-driven immune destruction of melanocytes (MCs). Although narrowband ultraviolet B (NBUVB) phototherapy has been proven to be an effective therapeutic option, the repigmentation response to that phototherapy varies greatly in different vitiligo patients. Here, we demonstrate that there is an increase of NBUVB-induced cellular senescence in vitiligo MCs exposed to Th1 cytokine interferon γ (IFNγ) and/or tumor necrosis factor α (TNFα) in lesional vitiligo skin from poor responders who had undergone NBUVB phototherapy. Supplementation with exogenous recombinant human stem cell factor (rhSCF) in the culture medium as well as the lentiviral vector-mediated overexpression of cKIT could prevent the MCs from the IFNγ/TNFα-accelerated cellular senescence. Mechanistic studies indicated that the reduced ratio of membrane-bound KIT (mKIT) to the soluble form of KIT (sKIT) is directly related to the cellular senescence of vitiligo MCs following exposure to IFNγ and TNFα. Furthermore, the matrix metalloprotease 9 (MMP9) inhibitor GM6001 attenuates the production of sKIT via the suppression of cKIT ectodomain shedding. Altogether, our study indicates that the presence of Th1 cytokines IFNγ and/or TNFα in the epidermal milieu might impair the repigmentation response of vitiligo patients to NBUVB phototherapy.

Efficacy and safety of combined fractional ablative CO2 laser and 5 fluorouracil in the treatment of acral vitiligo: An open, uncontrolled study

BACKGROUND

Acral lesions of vitiligo are most likely recalcitrant to the known lines of treatment. Ablative fractional CO₂ has shown efficacy in treatment of vitiligo in combination with other modalities.

METHODS

Thirty non-segmental vitiligo patients with acral lesion were included in the study. Each patient was subjected to fractional Carbon Dioxide Laser Treatment followed by application of 5 fluorouracil (5FU) cream for five consecutive days. Evaluation was done 3 weeks from the start of treatment and 12 weeks after the last treatment session using VESTA score, evaluation of patients' photos by blinded investigation in addition to patients' satisfaction scores.

RESULTS

Patients showed significant improvement of Vitiligo extent score for a target area (VESTA) score and developed considerable degree of repigmentation as assessed by blinded investigators.

CONCLUSION

The combination of fractional ablative CO₂ and 5FU is an effective and safe procedure for the treatment of acral vitiligo with promising results offering patients a new therapeutic window.

sPmel17 Secreted by Ultraviolet B-Exposed Melanocytes Alters the Intercellular Adhesion of Keratinocytes

Repigmentation of the skin in patients with vitiligo represents an intricate process in which the depigmented epidermis is replenished by functional melanocytes (MCs) that migrate from undamaged hair follicles and/or surrounding areas. We characterized whether MCs release a secreted form of Pmel17 (sPmel17) protein after exposure to UVB, thereby weakening the cell-cell adhesions of keratinocytes (KCs), which provides MCs the opportunity to migrate to areas devoid of MCs. At first, we examined the interactions of sPmel17 and FHL2 (four-and-a-half LIM domain protein 2) in KCs treated with the conditioned media (CM) from MCs exposed to UVB. The results showed that both the protein and mRNA levels of FHL2 were significantly upregulated in KCs treated with sPmel17-enriched CM from UVB-exposed MCs. We also found that there are physical interactions between sPmel17 and FHL2 as analyzed by reciprocal coimmunoprecipitation assays and double immunofluorescence staining. The CM from UVB-exposed MCs signaled KCs to remodel the actin cytoskeleton and reduce E-cadherin expression. However, the CM from UVB-exposed and Pmel17-silenced or from UVB-unexposed MCs failed to do this. To further determine the in situ distributions of sPmel17, FHL2, and E-cadherin, we examined the expression profiles of those proteins in the skin from healthy subjects and from depigmented or repigmented vitiligo using immunofluorescence and immunohistochemical staining. The results showed that the expression of sPmel17 was positively correlated with FHL2 but not to E-cadherin. The colocalization of FHL2 and sPmel17 was also observed in UVB-exposed mouse tail skin. Together, the upregulation of FHL2 in KCs requires stimulation by sPmel17 secreted from MCs and activation of the sPmel17-FHL2-E-cadherin axis offers a potential therapeutic target to expedite the repigmentation process in patients with vitiligo.