Impaired activation of the Nrf2-ARE signaling pathway undermines H2O2-induced oxidative stress response: a possible mechanism for melanocyte degeneration in vitiligo

Comparison of various excimer laser (EL) combination therapies for vitiligo: a systematic review and network meta-analysis

AIM

This study aimed to compare the efficacy and safety of excimer laser (EL)-based combination regimens in improving repigmentation.

METHODS

A comprehensive search was conducted in PubMed, Web of Science, Cochrane Library, and Embase on July 1, 2023, to include randomized controlled trials of EL combination treatments for vitiligo that met the criteria. The primary outcome measure was a repigmentation rate ≥ 75%, and the secondary outcome measures were a repigmentation rate of ≤ 25% and adverse events.

RESULTS

Eleven studies involving 348 patients were included. Network Meta-Analysis showed that EL combined with antioxidants (SUCRA = 98.8%), EL combined with calcipotriol (SUCRA = 59.8%) and EL combined with tacalcitol (SUCRA = 59.6%) were the three optimal interventions achieving repigmentation rates ≥ 75%. EL alone (SUCRA = 77.6%), EL combined with tacalcitol (SUCRA = 61.7%) and EL combined with antioxidants (SUCRA = 57.2%) were the three interventions with the highest rates of treatment failure. Adverse events in all groups mainly included erythema, burning sensation and hyperpigmentation. Based on the results of the current study, EL combination therapies were safe with mild adverse events.

CONCLUSION

EL combined with antioxidants was the preferred regimen for vitiligo, whereas EL alone was the regimen with the highest rate of treatment failure in vitiligo.

Post-translational modification in the pathogenesis of vitiligo

Vitiligo is a chronic dermatological condition marked by the loss of skin pigmentation. Its complex etiology involves multiple factors and has not been completely elucidated. Protein post-translational modification pathways have been proven to play a significant role in inflammatory skin diseases, yet research in the context of vitiligo remains limited. This review focuses on the role of post-translational modifications in vitiligo pathogenesis, especially their impact on cellular signaling pathways related to immune response and melanocyte survival. Current therapeutic strategies targeting these pathways are discussed, emphasizing the potential for novel treatments in vitiligo management.

The role of regulatory T cells in vitiligo and therapeutic advances: a mini-review

BACKGROUND

Regulatory T cells (Tregs) play vital roles in controlling immune reactions and maintaining immune tolerance in the body. The targeted destruction of epidermal melanocytes by activated CD8+T cells is a key event in the development of vitiligo. However, Tregs may exert immunosuppressive effects on CD8+T cells, which could be beneficial in treating vitiligo.

METHODS

A comprehensive search of PubMed and Web of Science was conducted to gather information on Tregs and vitiligo.

RESULTS

In vitiligo, there is a decrease in Treg numbers and impaired Treg functions, along with potential damage to Treg-related signaling pathways. Increasing Treg numbers and enhancing Treg function could lead to immunosuppressive effects on CD8+T cells. Recent research progress on Tregs in vitiligo has been summarized, highlighting various Treg-related therapies being investigated for clinical use. The current status of Treg-related therapeutic strategies and potential future directions for vitiligo treatment are also discussed.

CONCLUSIONS

A deeper understanding of Tregs will be crucial for advancing Treg-related drug discovery and treatment development in vitiligo.

3D-hUMSCs Exosomes Ameliorate Vitiligo by Simultaneously Potentiating Treg Cells-Mediated Immunosuppression and Suppressing Oxidative Stress-Induced Melanocyte Damage

Vitiligo is an autoimmune disease characterized by epidermal melanocyte destruction, with abnormal autoimmune responses and excessive oxidative stress as two cardinal mechanisms. Human umbilical mesenchymal stem cells-derived exosomes (hUMSCs-Exos) are regarded as promising therapeutic choice for autoimmune diseases due to potent immunosuppressive and anti-oxidative properties, which can be potentiated under 3D cell culture condition. Nevertheless, whether exosomes derived from 3D spheroids of hUMSCs (3D-Exos) exhibit considerable therapeutic effect on vitiligo and the underlying mechanism remain elusive. In this study, systemic administration of 3D-Exos showed a remarkable effect in treating mice with vitiligo, as revealed by ameliorated skin depigmentation, less CD8+T cells infiltration, and expanded Treg cells in skin, and 3D-Exos exerted a better effect than 2D-Exos. Mechanistically, 3D-Exos can prominently facilitate the expansion of Treg cells in vitiligo lesion and suppress H2O2-induced melanocytes apoptosis. Forward miRNA profile analysis and molecular experiments have demonstrated that miR-132-3p and miR-125b-5p enriched in 3D-Exos greatly contributed to these biological effects by targeting Sirt1 and Bak1 respectively. In aggregate, 3D-Exos can efficiently ameliorate vitiligo by simultaneously potentiating Treg cells-mediated immunosuppression and suppressing oxidative stress-induced melanocyte damage via the delivery of miR-132-3p and miR-125b-5p. The employment of 3D-Exos will be a promising treament for vitiligo.

The Stressogenic Impact of Bacterial Secretomes Is Modulated by the Size of the Milk Fat Globule Used as a Substrate

Milk fat globules (MFGs) are produced by mammary epithelial cells (MECs) and originate from intracellular lipid droplets with a wide size distribution. In the mammary gland and milk, bacteria can thrive on MFGs. Herein, we aimed to investigate whether the response of MECs to the bacterial secretome is dependent on the MFG size used as a substrate for the bacteria, and whether the response differs between pathogenic and commensal bacteria. We used secretomes from both Bacillus subtilis and E. coli. Proinflammatory gene expression in MECs was elevated by the bacteria secretomes from both bacteria sources, while higher expression was found in cells exposed to the secretome of bacteria grown on large MFGs. The secretome of B. subtilis reduced lipid droplet size in MECs. When the secretome originated from E. coli, lipid droplet size in MEC cytoplasm was elevated with a stronger response to the secretome from bacteria grown on large compared with small MFGs. These results indicate that MEC response to bacterial output is modulated by bacteria type and the size of MFGs used by the bacteria, which can modulate the stress response of the milk-producing cells, their lipid output, and consequently milk quality.

Ritlecitinib, a JAK3/TEC family kinase inhibitor, stabilizes active lesions and repigments stable lesions in vitiligo

The efficacy of ritlecitinib, an oral JAK3/TEC family kinase inhibitor, on active and stable lesions was evaluated in patients with active non-segmental vitiligo in a phase 2b trial (NCT03715829). Patients were randomized to placebo or daily ritlecitinib 50 mg (with or without 4-week 100-mg or 200-mg loading dose), 30 mg, or 10 mg for 24 weeks. Active lesions showed greater baseline expression of inflammatory/immune markers IFNG and CCL5, levels of CD103, and T-cell infiltrates than stable lesions. Patients with more active than stable vitiligo lesions showed higher baseline serum levels of CXCL9 and PD-L1, while patients with more stable than active lesions showed higher baseline serum levels of HO-1. At Week 24, ritlecitinib 50 mg significantly stabilized mean percent change from baseline in depigmentation extent in both active lesions and stable lesions vs. placebo-response, with stable lesions showing greater repigmentation. After 24 weeks of treatment, ritlecitinib 50 mg increased expression of melanocyte markers in stable lesions, while Th1/Th2-related and co-stimulatory molecules decreased significantly in both stable and active lesions. Serum from patients with more active than stable lesions showed decreased levels of ICOS and NK cell activation markers. These data, confirmed at transcription/protein levels, indicate that stable lesion repigmentation occurs early with ritlecitinib, while active lesions require stabilization of inflammation first. ClinicalTrials.gov: NCT03715829.

Paeoniflorin regulates RhoA/ROCK1 and Nrf2 pathways in PDLIM1-dependent or independent manners in oxidative stressed melanocytes

BACKGROUND

The adhesive properties of vitiligo melanocytes have decreased under oxidative stress., cytoskeleton proteins can control cell adhesion. Paeoniflorin (PF) was proved to resist hydrogen peroxide (H2O2)-induced oxidative stress in melanocytes via nuclear factorE2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway.

OBJECTIVES

This study was to investigate whether PF exerts anti-oxidative effect through influencing cytoskeleton markers or potential signaling pathway.

METHODS

Human Oxidative Stress Plus array was used to identify the differentially expressed genes between H2O2 + PF group and H2O2 only group, in PIG1 and PIG3V melanocyte cell lines respectively. Western blotting was used to verify the PCR array results and to test the protein expression levels of cytoskeleton markers including Ras homolog family member A (RhoA), Rho-associated kinase 1 (ROCK1) and antioxidative marker Nrf2. Small interfering RNA was used to knock down PDZ and LIM domain 1 (PDLIM1).

RESULTS

PF increased the expressions of PDLIM1, RhoA and ROCK1 in H2O2-induced PIG1, in contrast, decreased the expressions of PDLIM1 and ROCK1 in H2O2-induced PIG3V. Knockdown of PDLIM1 increased the expressions of RhoA and Nrf2 in PF-pretreated H2O2-induced PIG1, and ROCK1 and Nrf2 in PF-pretreated H2O2-induced PIG3V.

CONCLUSIONS

PF regulates RhoA/ROCK1 and Nrf2 pathways in PDLIM1-dependent or independent manners in H2O2-induced melanocytes. In PIG1, PF promotes PDLIM1 to inhibit RhoA/ROCK1 pathway or activates Nrf2/HO-1 pathway, separately. In PIG3V, PF directly downregulates ROCK1 in PDLIM1-independent manner or upregulates Nrf2 dependent of PDLIM1.

Oxidative stress-induced hypermethylation and low expression of ANXA2R: Novel insights into the dysfunction of melanocytes in vitiligo

BACKGROUND

Vitiligo is a skin disorder with melanocyte destruction caused by complex interplay between multiple genetic and environmental factors. Recent studies have suggested DNA methylation is involved in the melanocyte damage, but the underlying mechanism remains unknown.

OBJECTIVE

To explore the abnormal DNA methylation patterns in vitiligo lesional and nonlesional skin, and the mechanism of DNA methylation involved in vitiligo pathogenesis.

METHODS

Initially, the genome-wide aberrant DNA methylation profiles in lesional and nonlesional skin of vitiligo were detect via Illumina methylation EPIC 850k Beadchip. Subsequently, a comprehensive analysis was conduct to investigate the genomic characteristics of differentially methylated regions (DMRs). Furthermore, the effects of key aberrant methylated genes on cell apoptosis and function of both melanocytes and keratinocytes were further identified and validated by western bloting, ELISA, and immunofluorescence.

RESULTS

Compared with nonlesional skins, we discovered 79 significantly differentially methylated CpG sites in vitiligo lesions. These DMRs were mainly located in the gene body and the TS1500 region. Annexin A2 receptor (ANXA2R), a crucial gene in cell apoptosis, was hypermethylated in vitiligo lesions. Furthermore, we showed that ANXA2R displayed hypermethylation and low expression levels in both keratinocytes and melanocytes of vitiligo patients, and the hypermethylated-triggered downregulation of ANXA2R under oxidative stress induced melanocyte apoptosis, and inhibited the secretion of stem cell factor (SCF) from keratinocytes thus impaired the survival of melanocytes.

CONCLUSIONS

Our study illustrates the DNA methylation modification in vitiligo, and further demonstrates the molecular mechanism of hypermethylated ANXA2R in the dysfunction of melanocytes under oxidative stress.

Endoplasmic Reticulum Dysfunction: An Emerging Mechanism of Vitiligo Pathogenesis

The endoplasmic reticulum (ER) is the main site of protein synthesis, transport, and modification. Its abnormal status has now emerged as an established cause of many pathological processes, such as tumors and autoimmune diseases. Recent studies also demonstrated that the defective functions of ER may lead to pigmentary diseases. Vitiligo is a depigmenting ailment skin disorder whose pathogenesis is now found to be associated with ER. However, the detailed mechanism is still unclear. In this review, we try to link the association between ER with its inter- and intra-organellar interactions in vitiligo pathogenesis and focus on the function, mechanism, and clinical potential of ER with vitiligo. Expand ER is found in melanocytes of vitiligo and ER stress (ERS) might be a bridge between oxidative stress and innate and adaptive immunity. Meanwhile, the tight association between ER and mitochondria or melanosomes in organelles levels, as well as genes and cytokines, is the new paradigm in the pathogenesis of vitiligo. This undoubtedly adds a new aspect to the understanding of vitiligo, facilitating the design of targeted therapies for vitiligo.

Exploring the Influence of Cold Plasma on Epidermal Melanogenesis In Situ and In Vitro

Epidermal melanin synthesis determines an individual's skin color. In humans, melanin is formed by melanocytes within the epidermis. The process of melanin synthesis strongly depends on a range of cellular factors, including the fine-tuned interplay with reactive oxygen species (ROS). In this context, a role of cold atmospheric plasma (CAP) on melanin synthesis was proposed due to its tunable ROS generation. Herein, the argon-driven plasma jet kINPen® MED was employed, and its impact on melanin synthesis was evaluated by comparison with known stimulants such as the phosphodiesterase inhibitor IBMX and UV radiation. Different available model systems were employed, and the melanin content of both cultured human melanocytes (in vitro) and full-thickness human skin biopsies (in situ) were analyzed. A histochemical method detected melanin in skin tissue. Cellular melanin was measured by NIR autofluorescence using flow cytometry, and a highly sensitive HPLC-MS method was applied, which enabled the differentiation of eu- and pheomelanin by their degradation products. The melanin content in full-thickness human skin biopsies increased after repeated CAP exposure, while there were only minor effects in cultured melanocytes compared to UV radiation and IBMX treatment. Based on these findings, CAP does not appear to be a useful option for treating skin pigmentation disorders. On the other hand, the risk of hyperpigmentation as an adverse effect of CAP application for wound healing or other dermatological diseases seems to be neglectable.

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.

ISG15-USP18 Dysregulation by Oxidative Stress Promotes IFN-γ Secretion from CD8+ T Cells in Vitiligo

Excessive oxidative stress is thought to play pathologic roles in cellular senescence and autoimmune disorders by inducing inflammation and breaking down immune tolerance. In this study, we sought to identify the factors linking oxidative stress to autoimmunity and cellular senescence in vitiligo, where elevated oxidative stress plays an important role. RNA sequencing analysis of hydrogen peroxide-treated melanocytes revealed upregulation of ISG15. The upregulation of ISG15 was observed in vitiligo skin tissues as well as in the blood of patients with vitiligo, whereas USP18 downregulation was observed in vitiligo melanocytes and vitiligo skin tissues. Oxidative stress induced hypermethylation of the USP18 promoter region in keratinocytes and melanocytes, and USP18 promoter hypermethylation was also confirmed in vitiligo skin tissues. Our results indicate that USP18 promoter hypermethylation caused by oxidative stress increases ISG15 expression in keratinocytes and melanocytes along with senescence changes, leading CD8+ T cells to produce IFN-γ, the main pathogenic cytokine in vitiligo. Therefore, the ISG15-USP18 network may be important in oxidative stress-induced autoimmunity and cellular senescence in vitiligo pathogenesis.

The role of aryl hydrocarbon receptor in vitiligo: a review

Vitiligo is an acquired autoimmune dermatosis characterized by patchy skin depigmentation, causing significant psychological distress to the patients. Genetic susceptibility, environmental triggers, oxidative stress, and autoimmunity contribute to melanocyte destruction in vitiligo. Due to the diversity and complexity of pathogenesis, the combination of inhibiting melanocyte destruction and stimulating melanogenesis gives the best results in treating vitiligo. The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that can regulate the expression of various downstream genes and play roles in cell differentiation, immune response, and physiological homeostasis maintenance. Recent studies suggested that AhR signaling pathway was downregulated in vitiligo. Activation of AhR pathway helps to activate antioxidant pathways, inhibit abnormal immunity response, and upregulate the melanogenesis gene, thereby protecting melanocytes from oxidative stress damage, controlling disease progression, and promoting lesion repigmentation. Here, we review the relevant literature and summarize the possible roles of the AhR signaling pathway in vitiligo pathogenesis and treatment, to further understand the links between the AhR and vitiligo, and provide new potential therapeutic strategies.

Caffeic acid derivative WSY6 protects melanocytes from oxidative stress by reducing ROS production and MAPK activation

Purpose

Vitiligo is a chronic depigmentation disease caused by a loss of functioning melanocytes and melanin from the epidermis. Oxidative stress-induced damage to melanocytes is key in the pathogenesis of vitiligo. WSY6 is a caffeic acid derivative synthesized from epigallocatechin-3-gallate (EGCG). This study is to investigate whether the new chemical WSY6 protected melanocytes from H2O2-induced cell damage and to elucidate the underlying molecular mechanism.

Patients and methods

The present study compared the antioxidative potential of WSY6 with EGCG in hydrogen peroxide (H2O2)-treated PIG1 cells. Western blotting was used to study the protein expression of cyto-c, cleaved-caspase3, cleaved-caspase9, and the activation of MAPK family members, including p38, ERK1/2, JNK and their phosphorylation in melanocytes. ROS assay kit to detect intracellular reactive oxygen species production; CCK8 and lactate dehydrogenase leak assay to detect cytotoxicity.

Results

EGCG and WSY6 ameliorated H2O2-induced oxidative stress damage in PIG1 cells in a does-dependent manner, while WSY6 was much more effective. WSY6 reduced cellular ROS production, cytochrome c release, downregulated caspase-3 and caspase-9 activation. MAPK pathway signaling including phosphorylated p38, ERK and JNK were observed under oxidative stress and can be much protected by pre-treatment of WSY6.

Conclusion

These results indicated that WSY6 could be a more powerful antioxidant than EGCG and protect melanocytes against oxidative cytotoxicity.

The underestimated role of mitochondria in vitiligo: From oxidative stress to inflammation and cell death

Vitiligo is an acquired depigmentary disorder characterized by the depletion of melanocytes in the skin. Mitochondria shoulder multiple functions in cells, such as production of ATP, maintenance of redox balance, initiation of inflammation and regulation of cell death. Increasing evidence has implicated the involvement of mitochondria in the pathogenesis of vitiligo. Mitochondria alteration will cause the abnormalities of mitochondria functions mentioned above, ultimately leading to melanocyte loss through various cell death modes. Nuclear factor erythroid 2-related factor 2 (Nrf2) plays a critical role in mitochondrial homeostasis, and the downregulation of Nrf2 in vitiligo may correlate with mitochondria damage, making both mitochondria and Nrf2 promising targets in treatment of vitiligo. In this review, we aim to discuss the alterations of mitochondria and its role in the pathogenesis of vitiligo.

Antioxidant mechanisms of mesenchymal stem cells and their therapeutic potential in vitiligo

Vitiligo is a skin pigmentation disorder caused by melanocyte damage or abnormal function. Reac-tive oxygen species Reactive oxygen species can cause oxidative stress damage to melanocytes, which in turn induces vitiligo. Traditional treatments such as phototherapy, drugs, and other methods of treatment are long and result in frequent recurrences. Currently, mesenchymal stem cells (MSCs) are widely used in the research of various disease treatments due to their excellent paracrine effects, making them a promising immunoregulatory and tissue repair strategy. Furthermore, an increasing body of evi-dence suggests that utilizing the paracrine functions of MSCs can downregulate oxidative stress in the testes, liver, kidneys, and other affected organs in animal models of certain diseases. Addition-ally, MSCs can help create a microenvironment that promotes tissue repair and regeneration in are-as with oxidative stress damage, improving the disordered state of the injured site. In this article, we review the pathogenesis of oxidative stress in vitiligo and promising strategies for its treatment.

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.

Aquaporin-3 Downregulation in Vitiligo Keratinocytes Increases Oxidative Stress of Melanocytes

Oxidative stress-induced melanocyte apoptosis is linked to the immune system and plays a critical role in the pathogenesis of vitiligo. Aquaporin-3 (AQP3), which is downregulated in vitiligo keratinocytes, regulates intracellular H2O2 accumulation. However, the role of AQP3 in oxidative stress is uncertain in vitiligo. This study investigated the effect of downregulated AQP3 on oxidative stress in vitiligo using lesional and non-lesional skin specimen sets from vitiligo patients and primary cultured adult normal human epidermal keratinocytes, with or without downregulation and overexpression of AQP3 in the presence or absence of H2O2 treatment. The levels of nuclear factor E2-related factor 2 (NRF2) and/or its main target, NAD(P)H quinone dehydrogenase 1 (NQO-1), were lower in the lesional keratinocytes and cultured keratinocytes with AQP3 knockdown, but were increased in keratinocytes upon AQP3 overexpression. Ratios of NRF2 nuclear translocation and NQO-1 expression levels were further reduced in AQP3-knockdown keratinocytes following H2O2 treatment. The conditioned media from AQP3-knockdown keratinocytes treated with H2O2 contained higher concentrations of reactive oxygen species (ROS). Moreover, the number of viable melanocytes was reduced when the conditioned media were added to the culture media. Overall, AQP3 downregulation in the keratinocytes of patients with vitiligo can induce oxidative stress in neighboring melanocytes, leading to melanocyte death.

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.

TanshinoneIIA inhibits melanocyte pyroptosis by regulating the ROS/NLRP3 signaling axis

BACKGROUND

Pyroptosis has been implicated in the development of human diseases, including vitiligo. TanshinoneIIA has been confirmed to play anti-vitiligo role. However, whether tanshinoneIIA inhibits vitiligo progression via regulating cell pyroptosis remains unclear.

METHODS

Hydrogen peroxide (H2 O2 )-induced melanocytes were used to mimic vitiligo cell model in vitro. Cell viability was assessed by cell counting kit 8 assay, and reactive oxygen species (ROS) production was detected by DCFH-DA staining. Nod-like receptor protein 3 (NLRP3) expression was detected by quantitative real-time PCR, western blot and immunofluorescence staining. Cell pyroptosis was measured using flow cytometry, and the contents of interleukin-1β and interleukin-18 were determined by ELISA. Besides, the protein levels of apoptosis-associated speck-like protein containing CARD (ASC) and cleaved-Caspase-1 were examined by western blot analysis.

RESULTS

H2 O2 could induce ROS production, NLRP3 expression and pyroptosis in melanocytes. TanshinoneIIA inhibited ROS production, pyroptosis, and the expression of NLRP3, ASC and cleaved-caspase-1 in H2 O2 -induced melanocytes. Compared with the function of ROS inhibitor (NAC), tanshinoneIIA acted as a ROS scavenger to relieve melanocyte pyroptosis. In addition, NLRP3 inhibitor (MCC950) also could aggravate the inhibition effect of tanshinoneIIA on melanocyte pyroptosis.

CONCLUSION

TanshinoneIIA suppressed melanocyte pyroptosis probably through modulating the ROS/NLRP3 signaling axis, which provides the evidence for therapeutic effect in vitiligo.

TMT-Based Quantitative Proteomic and Physiological Analyses on Serums of Chinese Patients with Active Vitiligo

Purpose

Vitiligo is an acquired depigmented skin disorder. Though genetic background, autoimmune dysregulation, and oxidative stress were reported involved in the development of vitiligo, the exact pathogenesis remains largely unknown. This study aimed to investigate potential functional proteins, pathways, and serum biomarkers involved in active vitiligo.

Patients and Methods

Tandem Mass Tags (TMT) method was used to determine differentially expressed proteins (DEPs) in serum samples between 11 active vitiligo patients and 7 healthy controls of Chinese Han population.

Results

A total of 31 DEPs were identified (P < 0.05, fold change >1.2), with 21 proteins upregulated and 10 proteins downregulated in the vitiligo group. DEPs were enriched in GO terms such as "extracellular exosome" and "immunoglobulin receptor binding", as well as KEGG pathways including "cysteine and methionine metabolism" and other immune-related pathways. Furthermore, ALDH1A1 and EEF1G achieved areas under receiver-operating characteristic (ROC) curve of 0.9221 and 0.8571, respectively. The expression levels of these 2 proteins were validated in another active vitiligo patient group.

Conclusion

Our research provided novel insight into serum proteomic profile for vitiligo patients, detecting ALDH1A1 and EEF1G as potential biomarkers for active vitiligo and therapeutic intervention. Our work also detected several DEPs and associated pathways in the serum of active vitiligo patients, reinforcing the roles of retinoic acid and exosome processes in vitiligo pathogenesis.

Roflumilast enhances the melanogenesis and attenuates oxidative stress-triggered damage in melanocytes

BACKGROUND

The management of vitiligo is challenging due to limited treatment options, and therapeutic strategy varies according to the active or stable stage of vitiligo. PDE4 inhibitor has been used to treat various skin diseases, but the efficacy in vitiligo treatment is mixed.

OBJECTIVE

In this study, we aimed to investigate whether roflumilast, a PDE4 inhibitor, induces melanogenesis and attenuates oxidative stress-triggered damage in melanocytes, and if so, what is the mechanism.

METHODS

Melanin content assay, qRT-PCR, western blotting, ELISA, immunofluorescence assays, immunohistochemistry, small interfering RNA, flow cytometry, and transmission electron microscopy were employed.

RESULTS

Our results demonstrated that roflumilast alone only slightly increased melanogenesis, however, the combination of roflumilast and forskolin could boost cAMP levels, hence promoting melanogenesis more significantly. Moreover, roflumilast attenuated H₂O₂-induced apoptosis and mitochondrial morphological changes in melanocytes by reducing ROS levels. Furthermore, roflumilast activated AhR/Nrf2 pathway via cAMP whereas AhR silencing blocked roflumilast-induced Nrf2 nuclear translocation and reversed the inhibitory effect of roflumilast on H₂O₂-induced ROS production. Finally, we observed that the lesional skin of active vitiligo patients exhibited higher PDE4 expression levels.

CONCLUSION

roflumilast enhances the melanogenesis effect of forskolin and protects melanocytes from H₂O₂-induced apoptosis by cAMP/AhR/Nrf2-activated ROS inhibition, highlighting its therapeutic potential in vitiligo treatment.

Development and validation of ferroptosis-related lncRNA signature and immune-related gene signature for predicting the prognosis of cutaneous melanoma patients

Ferroptosis, a form of cell death caused by iron-dependent peroxidation of lipids, plays an important role in cancer. Recent studies have shown that long noncoding RNAs (lncRNAs) are involved in the regulation of ferroptosis in tumor cells and are also closely related to tumor immunity. Immune cell infiltration in the tumor microenvironment affects the prognosis and clinical outcome of immunotherapy in melanoma patients, and immune cell classification may be able to accurately predict the prognosis of melanoma patients. However, the prognostic value of ferroptosis-related lncRNAs (FRLs) in melanoma has not been thoroughly explored, and it is difficult to define the immune characteristics of melanoma. We used The Cancer Genome Atlas (TCGA), the Genotype-Tissue Expression (GTEx) database, and the FerrDb database to identify FRLs. FRLs with prognostic value were evaluated in an experimental cohort utilizing univariate, LASSO (least absolute shrinkage and selection operator) and multivariate Cox regression, followed by in vitro assays evaluating the expression levels and the biological functions of three candidate FRLs. Kaplan-Meier (K-M) and receiver operating characteristic (ROC) curve analyses were used to assess the validity of the risk model, and the drug sensitivity of FRLs was examined by drug sensitivity analysis. The differentially expressed genes between the high- and low-risk groups in the risk model were enriched in the immune pathway, and we further found immune gene signatures (IRGs) that could predict the prognosis of melanoma patients through a series of methods including single-sample Gene Set Enrichment Analysis (ssGSEA). Finally, two GEO cohorts were used to validate the predictive accuracy and reliability of these two signature models. Our findings suggest that FRLs and IRGs have the potential to predict the prognosis of patients with cutaneous melanoma.

Treatment update for vitiligo based on autoimmune inhibition and melanocyte protection

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Vitiligo, from Pathogenesis to Therapeutic Advances: State of the Art

Vitiligo is an acquired hypopigmentation of the skin due to a progressive selective loss of melanocytes; it has a prevalence of 1-2% and appears as rounded, well-demarcated white macules. The etiopathology of the disease has not been well defined, but multiple factors contribute to melanocyte loss: metabolic abnormalities, oxidative stress, inflammation, and autoimmunity. Therefore, a convergence theory was proposed that combines all existing theories into a comprehensive one in which several mechanisms contribute to the reduction of melanocyte viability. In addition, increasingly in-depth knowledge about the disease's pathogenetic processes has enabled the development of increasingly targeted therapeutic strategies with high efficacy and fewer side effects. The aim of this paper is, by conducting a narrative review of the literature, to analyze the pathogenesis of vitiligo and the most recent treatments available for this condition.

NRF2 in dermo-cosmetic: From scientific knowledge to skin care products

The skin is the organ that is most susceptible to the impact of the exposome. Located at the interface with the external environment, it protects internal organs through the barrier function of the epidermis. It must adapt to the consequences of the harmful effects of solar radiation, the various chemical constituents of atmospheric pollution, and wounds associated with mechanical damage: oxidation, cytotoxicity, inflammation, and so forth. In this biological context, a capacity to adapt to the various stresses caused by the exposome is essential; otherwise, more or less serious conditions may develop accelerated aging, pigmentation disorders, atopy, psoriasis, and skin cancers. Nrf2-controlled pathways play a key role at this level. Nrf2 is a transcription factor that controls genes involved in oxidative stress protection and detoxification of chemicals. Its involvement in UV protection, reduction of inflammation in processes associated with healing, epidermal differentiation for barrier function, and hair regrowth, has been demonstrated. The modulation of Nrf2 in the skin may therefore constitute a skin protection or care strategy for certain dermatological stresses and disorders initiated or aggravated by the exposome. Nrf2 inducers can act through different modes of action. Keap1-dependent mechanisms include modification of the cysteine residues of Keap1 by (pro)electrophiles or prooxidants, and disruption of the Keap1-Nrf2 complex. Indirect mechanisms are suggested for numerous phytochemicals, acting on upstream pathways, or via hormesis. While developing novel and safe Nrf2 modulators for skin care may be challenging, new avenues can arise from natural compounds-based molecular modeling and emerging concepts such as epigenetic regulation.

NRF2 in the Epidermal Pigmentary System

Melanogenesis is a major part of the environmental responses and tissue development of the integumentary system. The balance between reduction and oxidation (redox) governs pigmentary responses, for which coordination among epidermal resident cells is indispensable. Here, we review the current understanding of melanocyte biology with a particular focus on the "master regulator" of oxidative stress responses (i.e., the Kelch-like erythroid cell-derived protein with cap'n'collar homology-associated protein 1-nuclear factor erythroid-2-related factor 2 system) and the autoimmune pigment disorder vitiligo. Our investigation revealed that the former is essential in pigmentogenesis, whereas the latter results from unbalanced redox homeostasis and/or defective intercellular communication in the interfollicular epidermis (IFE). Finally, we propose a model in which keratinocytes provide a "niche" for differentiated melanocytes and may "imprint" IFE pigmentation.

DCUN1D1, a new molecule involved in depigmentation via upregulating CXCL10

CD8⁺ T cells in the lesioned site play a crucial role in the pathogenesis of vitiligo. The chemokine CXCL10 secreted by keratinocytes regulates the migration of CD8⁺ T cells into the skin. In our previous study, we found that DCUN1D1 expression in vitiligo lesions positively correlates with Cxcl10 expression. In this study, the regulatory effect of DCUN1D1 on CXCL10 and cell function was investigated. DCUN1D1 protein expression was significantly higher in the skin tissue from vitiligo lesions compared with samples from healthy controls. High expression of DCUN1D1 in keratinocytes caused local hair depigmentation in mice, reduced melanin content, high infiltration of CD8⁺ T cells and increased CXCL10 expression. This suggested that DCUN1D1 may regulate CD8⁺ T-cell infiltration and depigmentation through CXCL10. Inhibition of DCUN1D1 expression in HaCaT cells abolished the IFN-γ-induced upregulation of p-JAK1, p-STAT1 and CXCL10, suppressed the H₂ O₂ -induced ROS generation and apoptosis, and upregulated tyrosinase expression in melanocytes. Collectively, these results show that DCUN1D1 is an important regulator of CXCL10 and may be a new target for the treatment of vitiligo.

Immunometabolism in the pathogenesis of vitiligo

Vitiligo is a common depigmenting skin disorder characterized by the selective loss of melanocytes. Autoimmunity, genetic, environmental, and biochemical etiology have been proposed in vitiligo pathogenesis. However, the exact molecular mechanisms of vitiligo development and progression are unclear, particularly for immunometabolism. Sporadic studies have suggested mitochondrial dysfunction, enhanced oxidative stress, and specific defects in other metabolic pathways can promote dysregulation of innate and adaptive immune responses in vitiligo. These abnormalities appear to be driven by genetic and epigenetic factors modulated by stochastic events. In addition, glucose and lipid abnormalities in metabolism have been associated with vitiligo. Specific skin cell populations are also involved in the critical role of dysregulation of metabolic pathways, including melanocytes, keratinocytes, and tissue-resident memory T cells in vitiligo pathogenesis. Novel therapeutic treatments are also raised based on the abnormalities of immunometabolism. This review summarizes the current knowledge on immunometabolism reprogramming in the pathogenesis of vitiligo and novel treatment options.

Drug delivery of natural products through nano-carriers for effective vitiligo therapy: A compendia review

BACKGROUND

Vitiligo is a depigmenting illness that causes white areas on the skin. Vitiligo's pathogenetic genesis is based on the melanocyte's autoimmune destruction, in which oxidative stress causes melanocyte molecular, organelle, and exposure of antigen, as well as melanocyte cell death, and so plays a role in vitiligo progression. Natural compounds have recently shown a wide range of therapeutic bioactivities against a number of skin disorders.

AIM

The aim of this work is drug delivery of natural products through nano-carriers for effective vitiligo therapy: A compendia review.

METHODS & MATERIALS

An online literature analysis was guided for vitiligo therapy, nanotechnology, phytochemical composition, and, types of vitiligo, types of nanomedicine. Appropriate information were taken from different electronic scientific databases such as Web of Science, Science Direct, Elsevier, Google Scholar, Springer, PubMed, and scripts.

RESULTS

Nano-carriers-based natural compounds provide a great relationship for the enhancement in the efficacy and safety of pharmacotherapeutic agents for the treatment of vitiligo.

DISCUSSION

In this study focuses on natural compounds' effects and processes on vitiligo models. Although topical therapy plays an important role in vitiligo treatment, its utility and patient compliance are hampered by adverse effects or inadequate efficacy. Novel drug delivery techniques can help improve topical medication delivery by improving epidermal localization, reducing side effects, and increasing effectiveness.

CONCLUSION

This paper covers the significant potential of herbal-derived active compounds as anti-vitiligo drugs, as well as new drug delivery as a viable carrier and future possibilities to investigate.

NRF2, a crucial modulator of skin cells protection against vitiligo, psoriasis, and cancer

The skin represents a physical barrier between the organism and the environment that has evolved to confer protection against biological, chemical, and physical insults. The inner layer, known as dermis, is constituted by connective tissue and different types of immune cells whereas the outer layer, the epidermis, is composed by different layers of keratinocytes and an abundant number of melanocytes, localized in the stratum basale of the epidermis. Oxidative stress is a common alteration of inflammatory skin disorders such as vitiligo, dermatitis, or psoriasis but can also play a causal role in skin carcinogenesis and tumor progression. Nuclear factor (erythroid-derived 2)-like 2 (NRF2) has emerged as a crucial regulator of cell defense mechanisms activating complex transcriptional programs that facilitate reactive oxygen species detoxification, repair oxidative damage and prevent xenobiotic-induced toxicity. Accumulating evidence suggests that the keratinocytes, melanocytes, and other skin cell types express high levels of NRF2, which is known to play a pivotal role in the skin homeostasis, differentiation, and metabolism during normal and pathologic conditions. In the present review, we summarize the current evidence linking NRF2 to skin pathophysiology and we discuss some recent modulators of NRF2 activity that have shown a therapeutic efficacy in skin protection against tumor initiation and common inflammatory skin conditions such as vitiligo or psoriasis, with a particular emphasis on natural compounds.

Shining Light on Autophagy in Skin Pigmentation and Pigmentary Disorders

Autophagy is a vital process for cell survival and it preserves homeostasis by recycling or disassembling unnecessary or dysfunctional cellular constituents. Autophagy ameliorates skin integrity, regulating epidermal differentiation and constitutive pigmentation. It induces melanogenesis and contributes to skin color through melanosome turnover. Autophagy activity is involved in skin phenotypic plasticity and cell function maintenance and, if altered, it concurs to the onset and/or progression of hypopigmentary and hyperpigmentary disorders. Overexpression of autophagy exerts a protective role against the intrinsic metabolic stress occurring in vitiligo skin, while its dysfunction has been linked to the tuberous sclerosis complex hypopigmentation. Again, autophagy impairment reduces melanosome degradation by concurring to pigment accumulation characterizing senile lentigo and melasma. Here we provide an updated review that describes recent findings on the crucial role of autophagy in skin pigmentation, thus revealing the complex interplay among melanocyte biology, skin environment and autophagy. Hence, targeting this process may also represent a promising strategy for treating pigmentary disorders.

Resveratrol Glycosides Impede Microglial Apoptosis and Oxidative Stress in Rats for Spinal Cord Injury

Spinal cord injury (SCI) usually occurs after severe trauma, which can lead to detrimental and unpredictable secondary diseases, including dyskinesia, paraplegia and even quadriplegia, resulting in seriously reduced quality of life among these patients. Oxidative damage is one of the major pathogenic factors of SCI. Resveratrol biologically exerts a significant antioxidant activity by increasing the levels of antioxidants and sequentially scavenging free radicals, so as to protect multiple organs from damage. This study investigates whether resveratrol can function as a protective mediator in SCI and the underlying mechanisms, aiming to provide a theoretical hint for the treatment of SCI. After establishment of SCI model in rats, serial doses of resveratrol were administrated. Afterwards, the therapeutic effects of resveratrol glycosides were evaluated by analyzing the motor function, spinal cord edema, cellular apoptosis and oxidative reaction in rats. Eventually, the potential mechanisms of resveratrol glycosides were studied via Western blotting. Our results showed that the pro-apoptosis proteins were highly expressed in the spinal cord tissue of rats after SCI. In comparison with healthy rats, those with SCI exhibited significant widespread dead neurons, glial cell apoptosis, oxidative stress and more serious functional defects. Nevertheless, resveratrol glycosides can ameliorate oxidative stress, inhibit the apoptosis of glial cells and neuronal death after SCI. Importantly, it can induce the activation of the Nrf2/HO-1 signal transduction pathway that mediated the alleviation of SCI in rats. Resveratrol can improve motor dysfunction after SCI, which may be a result of its anti-oxidation and anti-apoptotic effects via modulating the Nrf2 signal transduction pathway of microglia, which provides a new idea for the treatment of SCI.

Lycium barbarum polysaccharide promotes proliferation of human melanocytes via activating the Nrf2/p62 signaling pathway by inducing autophagy in vitro

Vitiligo is a skin disease characterized by lack of functional melanocytes. Lycium barbarum polysaccharide (LBP) has been demonstrated to preserve keratinocytes and fibroblasts against oxidative stress. This study aimed to explore the efficacy and underlying mechanisms of LBP on autophagy in H₂ O₂ -damaged human melanocytes. Cellular viability was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and annexin V-fluorescein isothiocyanate/propidium iodide double staining. Reverse transcription-polymerase chain reaction, western blotting and electron microscopy were performed to detect autophagy. The protein expression level of Nrf2 and p62 were assessed by western blotting. Plasmid transfection and lentiviral infection were used to overexpress and silence Nrf2 in PIG1 cells. LBP promoted the proliferation and inhibited apoptosis of H₂ O₂ -damaged PIG1 cells. LBP increased the proliferation of H₂ O₂ -damaged PIG1 cells via induction of autophagy, and Nrf2 shRNA experiment confirmed that LBP activated the Nrf2/p62 signal pathway. These results suggest that LBP may be used for the treatment of vitiligo. PRACTICAL APPLICATIONS: Goji berry is the mature and dried fruit of Lycium barbarum L., which is a common food with a long history in China, as well as a Traditional Chinese Medicine. Our previous research found that LBP could activated the Nrf2/ARE pathway in an ultraviolet (UV)-induced photodamage model of keratinocytes, and increase the levels of phase II detoxification and antioxidant enzymes. We firstly confirmed the anti-vitiligo effects of L. barbarum polysaccharide (LBP) by inducing autophagy and promoted proliferation of human melanocytes, and LBP induced autophagy via activating the Nrf2/p62 signaling pathway in this study. These results proved that LBP can be an effective therapy for vitiligo treatment.

Multimodal analyses of vitiligo skin identifies tissue characteristics of stable disease

Vitiligo is an autoimmune skin disease characterized by the destruction of melanocytes by autoreactive CD8⁺ T cells. Melanocyte destruction in active vitiligo is mediated by CD8⁺ T cells, but the persistence of white patches in stable disease is poorly understood. The interaction between immune cells, melanocytes, and keratinocytes in situ in human skin has been difficult to study due to the lack of proper tools. We combine noninvasive multiphoton microscopy (MPM) imaging and single-cell RNA-Seq (scRNA-Seq) to identify subpopulations of keratinocytes in stable vitiligo patients. We show that, compared with nonlesional skin, some keratinocyte subpopulations are enriched in lesional vitiligo skin and shift their energy utilization toward oxidative phosphorylation. Systematic investigation of cell-to-cell communication networks show that this small population of keratinocyte secrete CXCL9 and CXCL10 to potentially drive vitiligo persistence. Pseudotemporal dynamics analyses predict an alternative differentiation trajectory that generates this new population of keratinocytes in vitiligo skin. Further MPM imaging of patients undergoing punch grafting treatment showed that keratinocytes favoring oxidative phosphorylation persist in nonresponders but normalize in responders. In summary, we couple advanced imaging with transcriptomics and bioinformatics to discover cell-to-cell communication networks and keratinocyte cell states that can perpetuate inflammation and prevent repigmentation.

Aberrant HO-1/NQO1-Reactive Oxygen Species-ERK Signaling Pathway Contributes to Aggravation of TPA-Induced Irritant Contact Dermatitis in Nrf2-Deficient Mice

NF-erythroid 2-related factor 2 (Nrf2) is a major transcription factor to protect cells against reactive oxygen species (ROS) and reactive toxicants. Meanwhile, Nrf2 can inhibit contact dermatitis through redox-dependent and -independent pathways. However, the underlying mechanisms of how Nrf2 mediates irritant contact dermatitis (ICD) are still unclear. In this article, we elucidated the role of Nrf2 in 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced acute ICD. Our study demonstrated that the ear thickness, redness, swelling, and neutrophil infiltration were significantly increased, accompanied by increased expression of inflammatory cytokines (IL-1α, IL-1β, IL-6, etc.) and decreased expression of antioxidant genes (HO-1 and NQO1) in Nrf2 knockout mice. Moreover, ERK phosphorylation was elevated in mouse embryonic fibroblasts (MEFs) from Nrf2 knockout mouse. Inhibition of ERK significantly alleviated TPA-induced cutaneous inflammation and ROS accumulation in MEFs derived from mouse. Conversely, ROS scavenging inhibited the ERK activation and TPA-induced inflammation in MEFs. Taken together, the findings illustrate the key role of the Nrf2/ROS/ERK signaling pathway in TPA-induced acute ICD.

Research Progress on Targeted Antioxidant Therapy and Vitiligo

Vitiligo is a common acquired depigmenting disease characterized by the loss of functional melanocytes and epidermal melanin. Vitiligo has a long treatment cycle and slow results, which is one of the most difficult challenges for skin diseases. Oxidative stress plays an important role as an initiating and driving factor in the pathogenesis of vitiligo. Antioxidant therapy has recently become a research hotspot in vitiligo treatment. A series of antioxidants has been discovered and applied to the treatment of vitiligo, which has returned satisfactory results. This article briefly reviews the relationship between oxidative stress and vitiligo. We also describe the progress of targeted antioxidant therapy in vitiligo, with the aim of providing a reference for new drug development and treatment options for this condition.

Four-Octyl Itaconate Attenuates UVB-Induced Melanocytes and Keratinocytes Apoptosis by Nrf2 Activation-Dependent ROS Inhibition

Vitiligo is an acquired skin depigmentation disease in which excessive reactive oxygen species (ROS) play a critical pathogenic role in melanocyte destruction. The complex crosstalk between melanocytes and keratinocytes in vitiligo suggests that treatments aimed at protecting both the cells might be meaningful. In this study, we investigated the effect of 4-octyl itaconate (4-OI), an itaconate derivative, on ultraviolet B- (UVB-) induced apoptosis in HaCaT and PIG1 cells and the underlying mechanisms. HaCaT and PIG1 cells were pretreated with 4-OI (50 or 100 μM) for 24 h and then exposed to 300 mJ/cm2 UVB (emission range 290–320 nm, emission peak 310 nm). ROS levels and cell apoptosis were investigated using fluorescence microscopy and flow cytometry 24 h after irradiation. In addition, nuclear translocation and the expression of pathway-related proteins and mRNAs were detected using confocal microscopy, western blotting, and qRT-PCR, respectively. Our results demonstrated that UVB induced apoptosis in HaCaT and PIG1 cells, whereas inhibition of ROS production could reverse this effect. Furthermore, 4-OI attenuated UVB-induced apoptosis in HaCaT and PIG1 cells in a concentration-dependent manner by reducing the ROS levels. Moreover, 4-OI induced nuclear translocation and activation of nuclear factor erythroid 2-related factor 2 (Nrf2), and Nrf2 silencing reversed the inhibitory effect of 4-OI on the UVB-induced increase in ROS production and apoptosis in HaCaT and PIG1 cells. In addition, in vivo experiments using the Institute of Cancer Research mouse model showed that 4-OI via tail vein injection (10 mg/kg/day for six consecutive days) could reduce skin damage induced by UVB (400 mJ/cm2/day for five consecutive days). In conclusion, 4-OI can protect melanocytes and keratinocytes from UVB-induced apoptosis by Nrf2 activation-dependent ROS inhibition and can potentially treat skin disorders associated with oxidative stress, such as vitiligo.

Potential Role of Chronic Physical Exercise as a Treatment in the Development of Vitiligo

Vitiligo is an autoimmune disease characterized by progressive skin depigmentation and the appearance of white patches throughout the body caused by significant apoptosis of epidermal melanocytes. Despite not causing any physical pain, vitiligo can originate several psychosocial disorders, drastically reducing patients' quality of life. Emerging evidence has shown that vitiligo is associated with several genetic polymorphisms related to auto-reactivity from the immune system to melanocytes. Melanocytes from vitiligo patients suffer from excess reactive oxygen species (ROS) produced by defective mitochondria besides a poor endogenous antioxidant system (EAS). This redox imbalance results in dramatic melanocyte oxidative stress (OS), causing significant damage in proteins, lipid membranes, and DNA. The damaged melanocytes secret damage-associated molecular pattern (DAMPs), inducing and increasing inflammatory gene expression response that ultimately leads to melanocytes apoptosis. Vitiligo severity has been also associated with increasing the prevalence and incidence of metabolic syndrome (MetS) or associated disorders such as insulin resistance and hypercholesterolemia. Thus, suggesting that in genetically predisposed individuals, the environmental context that triggers MetS (i.e., sedentary lifestyle) may also be an important trigger for the development and severity of vitiligo disease. This paper will discuss the relationship between the immune system and epidermal melanocytes and their interplay with the redox system. Based on state-of-the-art evidence from the vitiligo research, physical exercise (PE) immunology, and redox system literature, we will also propose chronic PE as a potential therapeutic strategy to treat and prevent vitiligo disease progression. We will present evidence that chronic PE can change the balance of inflammatory to an anti-inflammatory state, improve both EAS and the mitochondrial structure and function (resulting in the decrease of OS). Finally, we will highlight clinically relevant markers that can be analyzed in a new research avenue to test the potential applicability of chronic PE in vitiligo disease.

Vitamin K2 (Menaquinone-7) Reverses Age-Related Structural and Cognitive Deterioration in Naturally Aging Rats

Aging is a naturally occurring process inevitably affecting each living human. The brain is adversely affected by aging with increased risks of developing various neurological disorders. Thus, it is essential to investigate practical approaches that can counteract the impact of aging on the brain. Vitamin K2 (Vit. K2) is a naturally occurring vitamin with reported valuable therapeutic effects. The current study highlights the role of Vit. K2 administration in counteracting age-related changes in the brain using naturally aging rats. Three-month-old rats were assigned to two groups: an ageing control group receiving a drug vehicle and an ageing group orally gavaged with Vit. K2 (30 mg/kg, once daily 5 days per week). Treatment was continued for 17 months. Ten three-month-old rats were used as the adult control. Vit. K2 improved functional performance, reduced social anxiety, depressive-like behavior, and enhanced memory performance with concomitant preservation of hippocampal and cerebral cortex tyrosine hydroxylase expression. Biochemically, Vit. K2 administration restored oxidative-anti-oxidative homeostasis in the brain. Vit. K2 modulated inflammatory signaling, as evidenced by suppression in the brain of NLRP3, caspase-1, Il-1β, TNFα, IL-6, and CD68 expression. Concomitantly, histopathological examination revealed consistent hippocampal and cerebral cortex improvement. Thus, it can be inferred that Vit K2 can slow down age-related changes in the brain associated with modulation of NLRP3/caspase-1/Nrf-2 signaling.

Oxeiptosis: a novel pathway of melanocytes death in response to oxidative stress in vitiligo

Vitiligo is a cutaneous depigmenting autoimmune disease caused by the extensive destruction of epidermal melanocytes. Convincing data has defined a critical role for oxidative stress in the pathogenesis of vitiligo. Oxeiptosis is a caspase-independent cell death modality that was reportedly triggered by oxidative stress and operative in pathogen clearance. However, whether oxeiptosis exists in oxidative stress-induced melanocytes demise in vitiligo remains undetermined. In the present study, we initially found that other cell death modalities might exist in addition to the well-recognized apoptosis and necroptosis in H₂O₂-treated melanocytes. Furthermore, AIFM1 was found to be dephosphorylated at Ser116 in oxidative stress-induced melanocytes death, which was specific to oxeiptosis. Moreover, KEAP1 and PGAM5, upstream of the AIFM1 in oxeiptosis, were found to operate in melanocytic death. Subsequently, the KEAP1-PGAM5-AIFM1 signaling pathway was proved to be involved in oxidative stress-triggered melanocytes demise through the depletion of KEAP1 and PGAM5. Altogether, our study indicated that oxeiptosis might occur in melanocytes death under oxidative stress and contribute to the pathogenesis of vitiligo.

The Role of Oxidative Stress in the Pathogenesis of Vitiligo: A Culprit for Melanocyte Death

Vitiligo is a common chronic acquired pigmentation disorder characterized by loss of pigmentation. Among various hypotheses proposed for the pathogenesis of vitiligo, oxidative stress-induced immune response that ultimately leads to melanocyte death remains most widely accepted. Oxidative stress which causes elevated levels of reactive oxygen species (ROS) can lead to dysfunction of molecules and organelles, triggering further immune response, and ultimately melanocyte death. In recent years, a variety of cell death modes have been studied, including apoptosis, autophagy and autophagic cell death, ferroptosis, and other novel modes of death, which will be discussed in this review in detail. Oxidative stress is also strongly linked to these modes of death. Under oxidative stress, ROS could induce autophagy by activating the Nrf2 antioxidant pathway of melanocytes. However, persistent stimulation of ROS might eventually lead to excessive activation of Nrf2 antioxidant pathway, which in turn will inactivate autophagy. Moreover, ferroptosis may be triggered by oxidative-related transcriptional production, including ARE, the positive feedback loop related to p62, and the reduced activity and expression of GPX4. Therefore, it is reasonable to infer that these modes of death are involved in the oxidative stress response, and that oxidative stress also acts as an initiator for various modes of death through some complex mechanisms. In this study, we aim to summarize the role of oxidative stress in vitiligo and discuss the corresponding mechanisms of interaction between various modes of cell death and oxidative stress. These findings may provide new ideas for exploring the pathogenesis and potential therapeutic targets of vitiligo.

Folic Acid Protects Melanocytes from Oxidative Stress via Activation of Nrf2 and Inhibition of HMGB1

Vitiligo is a cutaneous depigmentation disease due to loss of epidermal melanocytes. Accumulating evidence has indicated that oxidative stress plays a vital role in vitiligo via directly destructing melanocytes and triggering inflammatory response that ultimately undermines melanocytes. Folic acid (FA), an oxidized form of folate with high bioavailability, exhibits potent antioxidant properties and shows therapeutic potential in multiple oxidative stress-related diseases. However, whether FA safeguards melanocytes from oxidative damages remains unknown. In this study, we first found that FA relieved melanocytes from H₂O₂-induced abnormal growth and apoptosis. Furthermore, FA enhanced the activity of antioxidative enzymes and remarkably reduced intracellular ROS levels in melanocytes. Subsequently, FA effectively activated nuclear factor E2-related factor 2 (Nrf2) pathway, and Nrf2 knockdown blocked the protective effects of FA on H₂O₂-treated melanocytes. Additionally, FA inhibited the production of proinflammatory HMGB1 in melanocytes under oxidative stress. Taken together, our findings support the protective effects of FA on human melanocytes against oxidative injury via the activation of Nrf2 and the inhibition of HMGB1, thus indicating FA as a potential therapeutic agent for the treatment of vitiligo.

Plant-Derived Compounds as Promising Therapeutics for Vitiligo

Vitiligo is the most common depigmenting disorder characterized by white patches in the skin. The pathogenetic origin of vitiligo revolves around autoimmune destruction of melanocytes in which, for instance, oxidative stress is responsible for melanocyte molecular, organelle dysfunction and melanocyte specific antigen exposure as well as melanocyte cell death and thus serves as an important contributor for vitiligo progression. In recent years, natural products have shown a wide range of pharmacological bioactivities against many skin diseases, and this review focuses on the effects and mechanisms of natural compounds against vitiligo models. It is showed that some natural compounds such as flavonoids, phenols, glycosides and coumarins have a protective role in melanocytes and thereby arrest the depigmentation, and, additionally, Nrf2/HO-1, MAPK, JAK/STAT, cAMP/PKA, and Wnt/β-catenin signaling pathways were reported to be implicated in these protective effects. This review discusses the great potential of plant derived natural products as anti-vitiligo agents, as well as the future directions to explore.

CUL5-Mediated Visfatin (NAMPT) Degradation Blocks Endothelial Proliferation and Angiogenesis via the MAPK/PI3K-AKT Signaling

ABSTRACT

Endothelial dysfunction participates in the pathogenesis of various cardiovascular disorders, and dysregulated angiogenesis involves the vascular endothelial growth factor (VEGF)-matrix metalloproteinases (MMP) system. Nicotinamide phosphoribosyltransferase (NAMPT) is known to enhance endothelial function and angiogenesis. The study found that NAMPT overexpression protected human coronary artery endothelial cells (HCAECs) from H2O2-induced injury through promoting cell viability, inhibiting cell apoptosis, enhancing cell motility, and promoting tube formation. Through analyses based on 2 Protein-Protein Interaction databases, Mentha and BioGrid, we identified CUL5 as a protein that may interact with NAMPT, which was then validated by Co-IP experiments. Through interacting with NAMPT, CUL5 inhibited NAMPT expression. In contrast to NAMPT, CUL5 overexpression further aggravated H2O2-induced HCAEC dysfunction. In the meantime, CUL5 overexpression reduced, whereas NAMPT overexpression increased the phosphorylation of p38 and Akt and the protein levels of VEGF and MMP2. More importantly, NAMPT overexpression partially reversed the effects of CUL5 overexpression on H2O2-stimulated HCAECs and the MAPK/phosphatidylinositol 3-kinase-Akt/VEGF/MMP signaling. In conclusion, CUL5 interacts with NAMPT in H2O2-stimulated HCAECs, suppressing cell viability, promoting cell apoptosis, and inhibiting cell mobility and tube formation. NAMPT overexpression protects against H2O2-induced HCAEC dysfunction by promoting cell viability, inhibiting cell apoptosis, and enhancing cell mobility and tube formation.

Repigmentation by combined narrow‑band ultraviolet B/adipose‑derived stem cell transplantation in the mouse model: Role of Nrf2/HO‑1‑mediated Ca2+ homeostasis

Vitiligo is a depigmentation disease commonly seen in clinical practice, mainly involving loss of functional epidermal pigment cells and hair follicle melanocytes. Narrow‑band ultraviolet B (NB‑UVB) has emerged as the first choice of treatment for vitiligo, but long‑term exposure may have serious consequences. Recently, it was reported that adipose‑derived stem cells (ADSCs) improve melanocyte growth and the efficacy of melanocyte transplantation. The present study aimed to examine the efficacy of NB‑UVB/ADSC‑transplantation combined therapy on a mouse vitiligo model and explore the underlying mechanisms by focusing on endoplasmic reticulum stress and cellular calcium (Ca²⁺) homeostasis. Vitiligo mice models were established by applying 40% monobenzone (MBZ) cream twice daily and treated with NB‑UVB/ADSC combination therapy. Some treated mice were also given ML385, a nuclear factor erythroid 2 like 2 (Nr2) inhibitor. Histopathological changes were evaluated using a depigmentation evaluation score and observed with hematoxylin and eosin staining on skin tissues. ELISA was used to measure diagnostic markers in plasma. Flow cytometric assay was performed to quantify CD3⁺, CD4⁺ and CD8⁺ levels. Expression levels of associated proteins were detected with western blot and immunofluorescence. Treatment of mice with MBZ‑induced depigmentation patches on the skin was accompanied with loss of redox balance and disruption of cellular Ca²⁺ homeostasis. Oxidative stress and Ca²⁺ unbalancing were improved after the mice were treated by NB‑UVB/ADSCs transplantation combination therapy. ML385, strongly negated the protective effect of NB‑UVB/ADSC transplantation combination therapy, indicating the critical role of Nr2 signaling. The findings improved the understanding of the pathogenesis of vitiligo and will guide future development of therapeutic strategies against it.

Successful Treatment of Vitiligo with Cold Atmospheric Plasma‒Activated Hydrogel

Vitiligo shows insufficient response to current therapies largely owing to T-lymphocyte dysfunction, abnormal inflammatory activation, and excessive oxidative stress in lesions. Cold atmospheric plasma (CAP) possesses pleiotropic antioxidant and anti-inflammatory properties and may offer an improvement to current treatment options. In this study, the efficacy and safety of CAP were investigated in a mouse model of vitiligo and a randomized and controlled trial of patients with active focal vitiligo. Skin biopsies showed that topical treatment of vitiligo-like lesions on mouse dorsal skin by CAP restored the distribution of melanin. In addition, CAP treatment reduced the infiltration of CD11c+ dendritic cells, CD3+ T cells, and CD8+ T cells; inhibited the release of CXCL10 and cytokine IFN-γ; and enhanced cellular resistance to oxidative stress and excessive immune response by enhancing the expression of the transcription factor NRF2 and attenuating the activity of inducible nitric oxide synthase. In a randomized and controlled trial, CAP treatment achieved partial and complete repigmentation in 80% and 20% of vitiligo lesions, respectively, without hyperpigmentation in surrounding areas or other adverse events during the treatment period and its follow-up period. In conclusion, CAP offers a promising option for the management of vitiligo.