Melanocyte-specific immune response in melanoma and vitiligo: two faces of the same coin?

Decreased GZMB, NRP1, ITPR1, and SERPINB9 Transcripts Lead to Reduced Regulatory T Cells Suppressive Capacity in Generalized Vitiligo Patients

Generalized vitiligo (GV) is an autoimmune skin disease characterized by bilateral white patches over the entire body. Regulatory T cells (Tregs) maintain peripheral tolerance; however, they are found to be reduced in numbers and function in vitiligo patients. The exact mechanism for reduced Treg suppressive capacity is unknown. Therefore, we aimed to assess transcript levels of Tregs-associated immunosuppressive genes (GZMB, NRP1, PDCD1, FASLG, and TNFRS18), regulatory molecules of Tregs suppressive function (SERPINB9, ITPR1, and UBASH3A), and Treg-associated transcription factors (GATA2, GATA3, RUNX1, STAT3, and STAT5) in 52 GV patients and 48 controls by real-time PCR (qPCR). We found significantly reduced GZMB, NRP1, SERPINB9, and ITPR1 transcripts in GV Tregs compared to controls (p = 0.03, p = 0.023, p = 0.0045, and p < 0.0001, respectively). There were 0.44-, 0.45-, 0.32-, and 0.54-fold decrease in GZMB, NRP1, SERPINB9, and ITPR1 transcripts in GV Tregs. Additionally, disease activity and severity-based analyses revealed significantly decreased GZMB (p = 0.019 and 0.034), SERPINB9 (p = 0.031 and p = 0.035), and ITPR1 (p = 0.0003 and p = 0.034) transcripts in active vitiligo and severe GV patients' Tregs. Interestingly, we found a positive correlation for ITPR1 with GZMB (r = 0.45, p = 0.0009) and SERPINB9 (r = 0.52, p = 0.001) transcripts in GV Tregs. Moreover, we found positive correlation for percentage Treg mediated suppression of CD4⁺ and CD8⁺T cells with ITPR1 (r = 0.54; r = 0.49), GZMB (r = 0.61; r = 0.58), NRP1 (r = 0.55; r = 0.52), and SERPINB9 (r = 0.56; r = 0.48) in GV Tregs. Further, calcium treatment of Tregs resulted into significantly increased ITPR1, SERPINB9, and GZMB transcripts in GV Tregs (p = 0.023, p = 0.0345, p = 0.02). Overall, our results for the first time revealed the crucial role of GZMB, NRP1, SERPINB9, and ITPR1 transcripts in decreased Treg suppressive capacity leading to GV pathogenesis, progression, and severity. In addition, our study highlighted that ITPR1 might be linked with decreased GZMB and NRP1 expression in GV Tregs. Moreover, our study for the first time suggest that increased SERPINB9 transcripts may lead to endogenous granzyme B-mediated Tregs apoptosis, and calcium treatment of Tregs may improve the Treg suppressive capacity. These findings may further aid in development of Treg-based therapeutics for GV.

A Concise Review on the Role of Endoplasmic Reticulum Stress in the Development of Autoimmunity in Vitiligo Pathogenesis

Vitiligo is characterized by circumscribed depigmented macules in the skin resulting due to the autoimmune destruction of melanocytes from the epidermis. Both humoral as well as cell-mediated autoimmune responses are involved in melanocyte destruction. Several studies including ours have established that oxidative stress is involved in vitiligo onset, while autoimmunity contributes to the disease progression. However, the underlying mechanism involved in programing the onset and progression of the disease remains a conundrum. Based on several direct and indirect evidences, we suggested that endoplasmic reticulum (ER) stress might act as a connecting link between oxidative stress and autoimmunity in vitiligo pathogenesis. Oxidative stress disrupts cellular redox potential that extends to the ER causing the accumulation of misfolded proteins, which activates the unfolded protein response (UPR). The primary aim of UPR is to resolve the stress and restore cellular homeostasis for cell survival. Growing evidences suggest a vital role of UPR in immune regulation. Moreover, defective UPR has been implicated in the development of autoimmunity in several autoimmune disorders. ER stress-activated UPR plays an essential role in the regulation and maintenance of innate as well as adaptive immunity, and a defective UPR may result in systemic/tissue level/organ-specific autoimmunity. This review emphasizes on understanding the role of ER stress-induced UPR in the development of systemic and tissue level autoimmunity in vitiligo pathogenesis and its therapeutics.

Toward Understanding the Repeated Occurrence of Associations between Melanin-Based Coloration and Multiple Phenotypes

Melanin is the most widespread pigment in organisms. Melanin-based coloration has been repeatedly observed to be associated with the same traits and in the same direction in different vertebrate and insect species. However, whether any factors that are common to different taxa account for the repeated evolution of melanin-phenotype associations remains unclear. We propose to approach this question from the perspective of convergent and parallel evolution to clarify to what extent different species have evolved the same associations owing to a shared genetic basis and being subjected to similar selective pressures. Our current understanding of the genetic basis of melanin-phenotype associations allows for both convergent and parallel evolution, but this understanding is still limited. Further research is needed to clarify the generality and interdependencies of the different proposed mechanisms (supergenes, pleiotropy based on hormones, or neural crest cells). The general ecological scenarios whereby melanin-based coloration is under selection-protection from ultraviolet radiation, thermoregulation in cold environments, or as a signal of social status-offer a good opportunity to study how melanin-phenotype associations evolve. Reviewing these scenarios shows that some traits associated with melanin-based coloration might be selected together with coloration by also favoring adaptation but that other associated traits might impede adaptation, which may be indicative of genetic constraints. We therefore encourage further research on the relative roles that selection and genetic constraints play in shaping multiple melanin-phenotype associations. Placed into a phylogenetic context, this will help clarify to what extent these associations result from convergent or parallel evolutionary processes and why melanin-phenotype associations are so common across the tree of life.

PD-L1 reverses depigmentation in Pmel-1 vitiligo mice by increasing the abundance of Tregs in the skin

Programmed cell death 1 ligand 1 (PD-L1) is a ligand of programmed cell death 1 (PD-1) that functions as an immune checkpoint by down-regulating immune responses. To determine whether PD-L1 is a therapy target in vitiligo treatment, Pmel-1 vitiligo mice were treated with a PD-L1 fusion protein. Treatment with this fusion protein significantly reversed/suppressed depigmentation development in adult Pmel-1 mice. Mechanistically, enrichment of regulatory T cells (Treg) in the skin was detected after PD-L1 fusion protein treatment in Pmel-1 mice. Furthermore, Tregs abundance was also increased in both the spleen and circulation of Pmel-1 mice treated with PD-L1. These data indicate that PD-L1 protein therapy inhibits the immune response and reverses depigmentation development in Pmel-1 vitiligo mice.

Efficacy of Cyclosporine After Autologous Noncultured Melanocyte Transplantation in Localized Stable Vitiligo-A Pilot, Open Label, Comparative Study

BACKGROUND

Understanding the pathogenesis of vitiligo has lead to innovation of new drugs and new uses of the existing drugs to enhance treatment outcome.

OBJECTIVE

The aim of this observational pilot study was to assess the role of cyclosporine (CsA) to tackle the commonest aesthetic problem "perilesional halo" after autologous noncultured melanocyte-keratinocyte cell transplant (NCMKT) for localized, stable vitiligo.

MATERIALS AND METHODS

Of the total 50 enrolled patients who underwent NCMKT for stable/resistant vitiligo, aged 12 to 68 years (mean 29.92 years), 18 were male and 32 were female. Group I (n = 25) patients did not receive any postoperative treatment. Group II (n = 25) patients received CsA postoperatively at 3 mg·kg·d for 3 weeks followed by 1.5 mg·kg·d for 6 weeks.

RESULTS

In Group I, results were as follows: 28% (n = 7) achieved >75% repigmentation, 16% (n = 4) achieved 50% to 75% repigmentation, 52% (n = 13) achieved 25% to 50% repigmentation, and 4% (n = 1) achieved <25% repigmentation. In Group II, 100% (n = 25) achieved >75% (median 90.7%) repigmentation post-NCMKT at the end of 6 months.

CONCLUSION

This new drug regimen using CsA resulted in rapid and uniform repigmentation without leaving any perilesional halo in Group II patients after NCMKT.

A similar local immune and oxidative stress phenotype in vitiligo and halo nevus

BACKGROUND

Vitiligo and halo nevus are two common T-cell-mediated skin disorders. Although autoimmunity has been suggested to be involved in both diseases, the relationship between vitiligo and halo nevus is not fully understood.

OBJECTIVE

The aim of the current study was to investigate whether vitiligo and halo nevus share the same immunological and oxidative stress response.

METHODS

Infiltrations of T cells, and expressions of chemokine receptors (CXCR3, CCR4, CCR5) and cytotoxic markers (Granzyme B, Perforin) in the lesions of vitiligo and halo nevus were examined by immunohistochemistry. Enzyme-linked immunosorbent assay was performed to analyze the expressions of chemokines in the serum samples and cytotoxic markers secreted by CD8⁺ T cells which were sorted from the peripheral blood mononuclear cells in healthy donors, vitiligo and halo nevus patients. Tissue levels of chemokine receptors and CXCR3 ligands in healthy controls, vitiligo patients and halo nevus patients were determined by qRT-PCR analysis. The percentages of CXCR3⁺ CD4⁺ T and CXCR3⁺ CD8⁺ T cells from the peripheral blood samples were examined by flow cytometry. Tissue and serum hydrogen peroxide (H₂O₂) concentrations were measured using H₂O₂ assay kit.

RESULTS

Immunohistochemistry revealed a significant T-cell response, with pronounced dermal infiltrates of CD8⁺ T cells in vitiligo and halo nevus. The inflammatory cytotoxic markers such as Granzyme B and Perforin were also elevated in vitiligo and halo nevus, suggesting inflammatory responses in situ. By qRT-PCR and ELISA assay, we found significantly increased expressions of the chemokine receptor CXCR3 and its ligands, especially the accumulated CXCL10 in the skin lesions of vitiligo and halo nevus. Moreover, the level of H₂O₂, a key player involved in regulation of the immune response was significantly upregulated in the skin lesions of vitiligo and halo nevus. In addition, the increased H₂O₂ concentration correlated positively with CXCL10 level in skin lesions of vitiligo and halo nevus.

CONCLUSIONS

These results demonstrate a H₂O₂-involved autoimmune phenotype in vitiligo and halo nevus, characterized by increased level of IFN-γ-inducible chemokine pair CXCL10-CXCR3, as well as a dense CD8⁺ T infiltration in the skin lesions, thus suggesting a similar pathogenesis of the two diseases.

Association of Vitiligo and Response in Patients with Metastatic Malignant Melanoma on Temozolomide

Vitiligo-like lesions, although rare, are believed to be a prognostic factor in malignant melanoma. While a predictive role for such lesions was shown with immunomodulatory therapies, this relation was not demonstrated with temozolomide. We present 3 patients with metastatic malignant melanoma who developed vitiligo-like skin lesions accompanying good response to treatment and prolonged survival. Onset of vitiligo-like lesions with temozolomide in metastatic malignant melanoma may predict long-term response for this treatment.

Amelanotic Acral Melanoma Associated with KIT Mutation and Vitiligo

Amelanotic acral melanoma is rare and difficult to diagnose, both clinically and pathologically. KIT mutations are frequently found in acral melanomas and are considered a risk factor for poor prognosis. The presence of vitiligo in melanoma has been reported, and KIT is thought to be partly responsible for the dysfunction and loss of melanocytes observed in vitiligo. We report a case of amelanotic subungual melanoma with multiple metastases that was associated with KIT mutation and vitiligo. An 85-year-old man presented with a 3-year history of a tender erythematous ulcerated tumor on the left third fingertip and developed hypopigmented patches on the face and trunk. Histopathological examination of the ulcerative tumor showed aggregates of tumor cells that were pleomorphic epithelioid cells. Immunohistochemical staining of the tumor cells was positive for S100, HMB45, and c-Kit. Histopathological findings from the hypopigmented patch on the face were consistent with vitiligo. Mutation analysis showed a KIT mutation in exon 17 (Y823D). The patient had metastasis to the brain, liver, bone, and both lungs. The patient refused chemotherapy, and died 3 months after the first visit.

Vitiligo--part 1

Vitiligo is a chronic stigmatizing disease, already known for millennia, which mainly affects melanocytes from epidermis basal layer, leading to the development of hypochromic and achromic patches. Its estimated prevalence is 0.5% worldwide. The involvement of genetic factors controlling susceptibility to vitiligo has been studied over the last decades, and results of previous studies present vitiligo as a complex, multifactorial and polygenic disease. In this context, a few genes, including DDR1, XBP1 and NLRP1 have been consistently and functionally associated with the disease. Notwithstanding, environmental factors that precipitate or maintain the disease are yet to be described. The pathogenesis of vitiligo has not been totally clarified until now and many theories have been proposed. Of these, the autoimmune hypothesis is now the most cited and studied among experts. Dysfunction in metabolic pathways, which could lead to production of toxic metabolites causing damage to melanocytes, has also been investigated. Melanocytes adhesion deficit in patients with vitiligo is mainly speculated by the appearance of Köebner phenomenon, recently, new genes and proteins involved in this deficit have been found.

A central role for inducible heat-shock protein 70 in autoimmune vitiligo

Inducible heat-shock protein 70 (HSP70i) is a protein regulated by stress that protects cells from undergoing apoptosis. Such proteins are marvellously well conserved throughout evolution, which has placed them in the spotlight for helping to understand the intriguing relationship between infection and immunity. In the presence of stress proteins, dendritic cells (DCs) will sense this alarm signal and respond by recruiting immune cells of different plumage to fit the occasion. In times of stress, melanocytes will secrete antigen-bound HSP70i to act as an alarm signal in activating DCs that comes equipped with an address of origin to drive the autoimmune response in vitiligo. Here we pose that if the autoimmune response is funnelled through HSP70i, then blocking the stress protein from activating DCs can lend new treatment opportunities for vitiligo.

CD8+ T cells from vitiligo perilesional margins induce autologous melanocyte apoptosis

Cell-mediated autoimmunity has been suggested to be involved in the melanocyte apoptosis that occurs in vitiligo. We investigated the cytotoxicity to autologous melanocytes of CD8⁺ T cells from the perilesional margins and peripheral blood samples of vitiligo patients. CD8⁺ T cells isolated from skin biopsied from the edges of depigmented skin patches of vitiligo patients or from peripheral blood samples of the same donors were proliferated in culture medium. The primary cultures of CD8⁺ T cells and autologous melanocytes were mixed at ratios of 1:1, 1:2 or 1:5 and incubated for 3 days. The apoptosis of the melanocytes was analyzed by flow cytometry. Secreted cytokines in selected samples were measured by cytokine arrays. The results show that the CD8⁺ T cells were successfully isolated from the vitiligo perilesional margins. This cell population showed a significantly higher percentage of CD69 expression (56.13±3.55 versus 29.93±2.35%, p<0.01) and CD137 expression (41.74±1.06 versus 25.97±1.63%, p<0.01) compared with CD8⁺ T cells in peripheral blood from the same donors. The co-culturing of CD8⁺ T cells from lesional skin with autologous melanocytes induced apoptosis in the melanocytes (16.63±1.21, 16.71±0.63 and 18.32±1.60% for CD8⁺ T cells and autologous melanocytes at ratios of 1:1, 1:2 and 1:5, respectively). IL-6 levels were much higher in the co-culture (3.01-fold higher than in a melanocyte monoculture and 17.32-fold higher than in a CD8⁺ T-cell monoculture). The CD8⁺ T cells were also demonstrated to secrete more IL-13. Taken together, our data demonstrate that the infiltration of active CD8⁺ T cells takes place in the vitiligo perilesional margins. Those CD8⁺ T cells present significantly higher activation levels and higher cytotoxicity to autologous melanocytes than their counterparts from peripheral blood samples. These data suggest that CD8⁺ T cells are likely to be involved in the pathogenesis of vitiligo.

Atypical clinical response patterns to ipilimumab

Patients with advanced melanoma have few treatment options, and survival is poor. However, improved understanding of how the immune system interacts with cancer has led to the development of novel therapies. Ipilimumab is a monoclonal antibody that inhibits cytotoxic T-lymphocyte antigen-4 (CTLA-4), a key negative regulator of host T-cell responses. This article presents cases of patients receiving ipilimumab in clinical trials along with a discussion of their significance and relevance to nursing practice. The patients showed different response patterns to ipilimumab and also had various typical immune-related adverse events (irAEs), which were managed successfully. The atypical response patterns produced by ipilimumab likely reflect its mechanism of action, which requires time for the immune system to mount an effective antitumor response. Meanwhile, lesions may appear to enlarge as a consequence of enhanced T-cell infiltration, although this may not necessarily be true disease progression. Patients receiving ipilimumab may respond very differently compared to how they might react to chemotherapy. Responses can take weeks or months to develop; therefore, clinicians should not terminate treatment prematurely, providing the patient's condition allows for continuation. Early recognition of irAEs combined with prompt management will ensure that events are more likely to resolve without serious consequences.

Clinical utility of serum autoantibodies detected by protein microarray in melanoma

Better prognostic and predictive markers in melanoma are needed to select patients for therapy. We utilized a dual-lectin affinity chromatography and a natural protein microarray-based analysis to select a subproteome of target glycoproteins to profile serum antibodies against melanoma associated antigens that may predict nodal positivity. We identified 5 melanoma-associated antigens using this microarray coupled to mass spectrometry; GRP75, GRP94, ASAH1, CTSD and LDHB. We evaluated their predictive value for nodal status adjusting for age, gender, Breslow thickness, mitotic rate and ulceration using standard logistic regression. After adjustment, ASAH1, CTSD and LDHB were significantly negatively associated with nodal status (P = 0.0008) and GRP94 was significantly positively associated (P = 0.014). Our best multivariate model for nodal positivity included Breslow thickness, presence of serum anti-ASAH1, anti-LDHB or anti-CTSD, and presence of serum anti-GRP94, with an area under the ROC curve of 0.869. If validated, these results show promise for selecting clinically node negative patients for SLN biopsy. In addition, there is strong potential for glycoprotein microarray to screen serum autoantibodies that may identify patients at high risk of distant metastases or those likely or unlikely to respond to treatment, and these proteins may serve as targets for intervention.

Proteomics in melanoma biomarker discovery: great potential, many obstacles

The present clinical staging of melanoma stratifies patients into heterogeneous groups, resulting in the application of aggressive therapies to large populations, diluting impact and increasing toxicity. To move to a new era of therapeutic decisions based on highly specific tumor profiling, the discovery and validation of new prognostic and predictive biomarkers in melanoma is critical. Genomic profiling, which is showing promise in other solid tumors, requires fresh tissue from a large number of primary tumors, and thus faces a unique challenge in melanoma. For this and other reasons, proteomics appears to be an ideal choice for the discovery of new melanoma biomarkers. Several approaches to proteomics have been utilized in the search for clinically relevant biomarkers, but to date the results have been relatively limited. This article will review the present work using both tissue and serum proteomics in the search for melanoma biomarkers, highlighting both the relative advantages and disadvantages of each approach. In addition, we review several of the major obstacles that need to be overcome in order to advance the field.

New perspectives on the role of vitiligo in immune responses to melanoma

Melanoma-associated vitiligo is the best-studied example of the linkage between tumor immunity and autoimmunity. Although vitiligo is an independent positive prognostic factor for melanoma patients, the autoimmune destruction of melanocytes was long thought to be merely a side effect of robust anti-tumor immunity. However, new data reveal a key role for vitiligo in supporting T cell responses to melanoma. This research perspective reviews the history of melanoma-associated vitiligo in patients, the experimental studies that form the basis for understanding this relationship, and the unique characteristics of melanoma-specific CD8 T cells found in hosts with vitiligo. We also discuss the implications of our recent findings for the interpretation of patient responses, and the design of next-generation cancer immunotherapies.

Cytotoxic T lymphocyte responses against melanocytes and melanoma

Background

Vitiligo is a common toxicity associated with immunotherapy for melanoma. Cytotoxic T lymphocytes (CTLs) against melanoma commonly target melanoma-associated antigens (MAAs) which are also expressed by melanocytes. To uncouple vitiligo from melanoma destruction, it is important to understand if CTLs can respond against melanoma and melanocytes at different levels.

Methods

To understand the dichotomous role of MAA-specific CTL, we characterized the functional reactivities of established CTL clones directed to MAAs against melanoma and melanocyte cell lines.

Results

CTL clones generated from melanoma patients were capable of eliciting MHC-restricted, MAA-specific lysis against melanocyte cell lines as well as melanoma cells. Among the tested HLA-A*0201-restricted CTL clones, melanocytes evoked equal to slightly higher degranulation and cytolytic responses as compared to melanoma cells. Moreover, MAA-specific T cells from vaccinated patients responded directly ex vivo to melanoma and melanocytes. Melanoma cells express slightly higher levels of MART-1 and gp100 than melanocytes as measured by quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) and immunohistochemistry.

Conclusions

Our data suggest that CTLs respond to melanoma and melanocytes equally in vitro and directly ex vivo.

Topical application of bleaching phenols; in-vivo studies and mechanism of action relevant to melanoma treatment

Skin depigmentation represents a well-established treatment for extensive vitiligo and may likewise be suited to prevent tumor recurrences and as a prophylactic treatment of familial melanoma, as common bleaching agents are cytotoxic to melanocytes. Effective melanoma prevention requires a bleaching agent-induced loss of exposed melanocytes supported by an immune response to distant pigment cells. Studies on human explant cultures treated with depigmenting agents such as 4-tertiary butyl phenol (4-TBP) or monobenzyl ether of hydroquinone (MBEH) showed a significant increase in the migration of Langerhans cells toward the dermis only upon treatment with MBEH, thus suggesting selective elicitation of an immune response. To assess the depigmenting potential of bleaching agents in vivo, 4-TBP and MBEH were topically applied to C57BL/6 wild type as well as k14-SCF transgenic, epidermally pigmented mice. MBEH-induced significant skin depigmentation in both strains was not observed upon treatment with 4-TBP. Cytokine expression patterns in skin treated with MBEH support activation of a Th1-mediated immune response corresponding to an influx of T cells and macrophages. Importantly, despite insensitivity of tumor cells to MBEH-induced cytotoxicity, significantly retarded tumor growth was observed in B16 challenged k14-SCF mice pretreated with MBEH, likely due to an abundance of cytotoxic T cells accompanied by an increased expression of Th1 and Th17 cytokines. These data support the use of MBEH as a prophylactic treatment for melanoma.

Evaluation of NLRP1 gene polymorphisms in Vogt-Koyanagi-Harada disease

PURPOSE

Polymorphisms of the NACHT [neuronal apoptosis inhibitory protein (NAIP), CIITA, HET-E, TP1] and leucine-rich repeat protein 1 (NLRP1) gene are reported to be associated with susceptibility to vitiligo and several autoimmune diseases. Vogt-Koyanagi-Harada (VKH) disease is an autoimmune disorder affecting melanocytes in the skin, eyes, inner ear, and meninges. In this study, genetic associations between VKH disease and single-nucleotide polymorphisms (SNPs) surrounding the NLRP1 gene were investigated.

METHODS

Six SNPs (rs6502867, rs925597, rs3926687, rs2733359, rs878329, and rs4790796) near the NLRP1 gene, including noncoding regions, were sequenced by a direct method to genotype 167 Japanese patients with VKH disease and 187 healthy Japanese volunteers.

RESULTS

None of the six SNPs in the NLRP1 region were significantly associated with disease susceptibility or the ocular, neurological, and dermatological manifestations of VKH.

CONCLUSIONS

Although skin manifestations are clinically similar between vitiligo and VKH disease, the genetic and immunological mechanisms of these two diseases may be different.

Mechanisms of spatial and temporal development of autoimmune vitiligo in tyrosinase-specific TCR transgenic mice

Generalized vitiligo is thought to have an autoimmune etiology and has been correlated with the presence of CD8 T cells specific for melanocyte differentiation Ag. However, limited animal models for the disease have hampered its understanding. Thus, we generated TCR transgenic mice that recognize an epitope of the melanocyte protein, tyrosinase. These animals develop vitiligo with strikingly similar characteristics to the human disease. Vitiligo develops temporally and spatially, with juvenile lesions forming bilaterally in head and facial areas, and only arising later in the body of adult animals. Vitiligo is entirely dependent on CD8 T cells, whereas CD4 T cells exert a negative regulatory effect. Importantly, CD8 T cells can be pervasively present in the skin in the steady state without inducing vitiligo in most areas. This points to developmental differences in melanocyte susceptibility and/or immunological effector mechanisms over time, or in different body locations. Disease is strongly dependent on both IFN-gamma and CXCR3, whereas dependence on CCR5 is more limited, and both CCR4 and perforin are dispensable. Genetic ablation of CXCR3 or IFN-gamma also resulted in scarce CD8 T cell infiltration into the skin. Our results identify unexpected complexity in vitiligo development and point toward possible therapeutic interventions.

Vaccine-specific local T cell reactivity in immunotherapy-associated vitiligo in melanoma patients

The occurrence of vitiligo in patients with melanoma is especially reported for patients undergoing immunotherapy. While vitiligo in these patients is thought to be related to an immune response directed against melanoma cells, solid evidence is lacking. Here we report local cytotoxic T cell reactivity in three melanoma patients who developed vitiligo, after experimental immunotherapy using dendritic cell vaccinations. Tetramer analysis showed that vaccine-induced T cells recognizing gp100 and tyrosinase are present at the vitiligo lesions. These T cells secrete IFN-gamma and IL-2 upon peptide specific stimulation as well as upon recognition of the autologous tumor. We show that functional CD8(+) T cells specific for melanoma differentiation antigens used in a melanoma immunotherapy trial, do not only invade the tumor, but also the vitiligo lesions. This directly links vitiligo to the immuno-therapeutic intervention and supports the hypothesis that vitiligo is a marker of immunity against melanoma cells.

Melanoma vaccines

Over the last century, vaccine studies have demonstrated that the human immune system, with appropriate help, can limit or prevent infection against otherwise lethal pathogens. Encouraged by these results, success in animal models and numerous well-documented reports of immune-mediated melanoma regression in humans, investigators developed melanoma vaccines. However, despite considerable laboratory evidence for vaccine-induced immune responses, clinical responses remain poor. Recent studies have elucidated several mechanisms that hinder or prevent the creation of successful vaccines and suggest novel approaches to overcome these barriers. Unraveling the mechanisms of autoimmunity, dendritic cell activation, regulatory T cells and Toll-like receptors will generate novel vaccines that, when used in conjunction with standard adjuvant therapies, may result in improved clinical outcomes. The objective of this review is to provide an overall summary of recent clinical trials with melanoma vaccines and highlight novel vaccine strategies to evaluate in the near future.

Vitiligo-like primary melanoma

Depigmented or hypopigmented macules and patches have been described in association to primary and metastatic melanoma. Primary melanoma presenting at the onset as a vitiliginous patch without histopathological evidence of regression seems to be a rare event. We report 2 patients with melanoma in situ that expressed clinically as vitiligo-like patches and review the possible immunologic mechanisms responsible for this unusual presentation.

Vitiligo associated with malignant melanoma and lupus erythematosus

There exists several reports where malignant melanoma is associated with vitiligo, vitiligo with discoid lupus erythematosus and lupus erythematosus with urticaria. However, there are no reports in which vitiligo, malignant melanoma, lupus erythematosus and urticaria coexist in the same case. Herein, we report a case of a patient who developed lupus erythematosus, malignant melanoma, vitiligo and urticaria simultaneously.

CD4 T Cell-Dependent Autoimmunity against a Melanocyte Neoantigen Induces Spontaneous Vitiligo and Depends upon Fas-Fas Ligand Interactions

Better understanding of tolerance and autoimmunity toward melanocyte-specific Ags is needed to develop effective treatment for vitiligo and malignant melanoma; yet, a systematic assessment of these mechanisms has been hampered by the difficulty in tracking autoreactive T cells. To address this issue, we have generated transgenic mice that express hen egg lysozyme as a melanocyte-specific neoantigen. By crossing these animals to a hen egg lysozyme-specific CD4 TCR transgenic line we have been able to track autoreactive CD4+ T cells from their development in the thymus to their involvement in spontaneous autoimmune disease with striking similarity to human vitiligo vulgaris and Vogt-Koyanagi-Harada syndrome. Our findings show that CD4-dependent destruction of melanocytes is partially inhibited by blocking Fas-Fas ligand interactions and also highlights the importance of local control of autoimmunity, as vitiligo remains patchy and never proceeds to confluence even when Ag and autoreactive CD4+ T cells are abundant. Immune therapy to enhance or suppress melanocyte-specific T cells can be directed at a series of semiredundant pathways involving tolerance and cell death.

Accumulation of low-avidity anti-melanocortin receptor 1 (anti-MC1R) CD8+ T cells in the lesional skin of a patient with melanoma-related depigmentation

Spontaneous or therapy-induced depigmentation in patients with melanoma has long been considered a favourable prognostic indicator. In this report, we isolated T cells infiltrating the depigmented skin of an HLA-A2+/DR4+ patient with melanoma, and detected a very high frequency of CD8+ T cells specific for melanocortin receptor 1 (MC1R), a hormone receptor involved in cutaneous pigmentation. In particular, tissue-infiltrating CD8+ T cells dominantly recognized the novel MC1R52-60 peptide epitope in an HLA-A2-restricted manner, and peptide-reactive CD8+ T cells were also detected in freshly isolated peripheral blood from this patient. Although type 1 CD4+ T-cell responses against MC1R were not detected in fresh tissue isolates, short-term in-vitro stimulation of peripheral blood lymphocytes resulted in the rapid expansion of CD4+ T cells reactive against novel HLA-DR4-presented epitopes derived from the MC1R protein (i.e. MC1R82-95, MC1R105-118 and MC1R149-161). MC1R peptide-specific CD8+ T-cell clones isolated from the depigmented skin of this patient were characterized by comparatively low functional avidity for specific major histocompatibility complex-peptide complexes and were poorly lytic; however, these effector cells were capable of secreting both interferon-gamma and granzyme B against relevant target cells in vitro, and may have played an important role in the induction of leucoderma in situ in this patient.

Skin diseases in consequence of endocrine alterations

The skin is a target organ of several hormones. Specific diseases appear in consequence of hypo- or hypersecretion of endocrine organs, particularly in the elderly patient. There, knowledge of skin alterations is important not only for dermatologists, but also for endocrinologists and other physicians, because a clinical diagnosis of the underlying disease is often possible. In this review, a number of representative skin diseases having an endocrinological basis are described. These include acanthosis nigricans, diseases due to alterations of androgen metabolism, carcinoid syndrome, diseases due to alterations of corticosteroid metabolism, diseases in association with diabetes mellitus, diseases due to alterations of estrogen metabolism, genetic syndromes including dermatological and endocrine symptoms, the glucagonoma syndrome, diseases due to dysfunctions of growth hormone secretion, diseases in association with Merkel cells of the skin, diseases due to dysfunctions of the thyroid gland, diseases to alteration of vitamin D metabolism, and vitiligo and disorders of pigmentation.

Qualitative difference between the cytotoxic T lymphocyte responses to melanocyte antigens in melanoma and vitiligo

Vitiligo is a skin disorder characterized by depigmented macules secondary to melanocyte loss. An unusual facet is its relation to melanoma: cytotoxic T lymphocytes directed to melanocyte antigens are found in both conditions and imply a breakdown of tolerance, yet the resulting immune reaction is the opposite. The mechanisms at the basis of these opposite effects are not known. Here, we performed a direct comparison of whole melanocyte-specific T cell populations in the two diseases. We demonstrate that neither precursor frequencies of Melan-A/MART-1-specific T lymphocytes nor their status of activation differ significantly. However, by using a tetramer-based T cell receptor down-regulation assay, we documented a higher affinity of vitiligo T cells. We calculated that the peptide concentration required for 50% of maximal receptor down-regulation differed by 6.5-fold between the two diseases. Moreover, only vitiligo T cells were capable of efficient receptor down-regulation and IFN-gamma production in response to HLA-matched melanoma cells, suggesting that this difference in receptor affinity is physiologically relevant. The differences in receptor affinity and tumor reactivity were confirmed by analyzing Melan-A/MART-1-specific clones established from the two diseases. Our results suggest that the quality, and not the quantity, of the melanocyte-specific cytotoxic responses differs between the two pathologies.

Grm5 expression is not required for the oncogenic role of Grm1 in melanocytes

Melanoma is the aberrant proliferation of melanocytes, the cells in the skin responsible for pigment (melanin) production. In its early stages, melanoma can be surgically removed with great success, however, advanced stages of melanoma have a high mortality rate due to the lack of responsiveness to currently available therapies. We have previously characterized a mouse melanoma model, TG-3, which has implicated the ectopic expression of metabotropic glutamate receptor 1 (Grm1, formerly mGluR1), in melanomagenesis and metastasis [Pollock et al., 2003. Melanoma mouse model implicates metabotropic glutamate signaling in melanocytic neoplasia. Nat Genet. 34, 108-112.]. Here we report the characterization of several in vitro cell lines derived from independent mouse melanoma tumors. These cell lines show characteristic phenotypes of transformed melanocytes, and express Grm1, and Grm5 (another metabotropic glutamate receptor), as well as melanocyte-specific protein markers. To investigate the possible role of Grm5 in vivo during melanoma development in our mice, we have crossed Grm5 null mice with TG-3, generating a new line of transgenic mice, TGM. TGMs, which are homozygote knockouts for Grm5 and carry the TG transgene, develop tumors with onset, progression, and metastasis very similar to that described for TG-3. Taken together, these results indicate that Grm1 can act as an oncogene in melanocytes independently of Grm5 expression.

Transfer of efficient anti-melanocyte T cells from vitiligo donors to melanoma patients as a novel immunotherapeutical strategy

BACKGROUND

Vitiligo is a relatively common progressive depigmentary condition that is believed to be due to the autoimmune-mediated loss of epidermal melanocytes. High frequencies of self-reactive T lymphocytes directed toward melanocyte differentiation antigens are found in vitiligo patients and might be directly responsible for the pathogenesis of the disease. An interesting aspect of vitiligo is its relation to melanoma: cytotoxic T lymphocytes directed to self antigens shared by normal melanocytes and melanoma cells are found in both conditions, but the resulting immune reactions are completely different. From this standpoint, the selective destruction of pigment cells that occurs in cases of vitiligo is the therapeutic goal sought in melanoma research.

PRESENTATION OF THE HYPOTHESIS

Our working hypothesis is that vitiligo patients might represent a unique source of therapeutic cells to be used in allo-transfer for HLA-matched melanoma patients. The adoptive transfer of ex-vivo generated autologous tumor-specific T cells is a therapy that has met with only limited success, essentially because of inability to isolate therapeutically valuable T cells from the majority of tumor patients. Ideally, model systems where strong and efficient responses against the same (tumor) antigens are achieved would represent a better source of therapeutic cells. We believe it is possible to identify one such model in the melanoma-vitiligo dichotomy: T lymphocytes specific for different melanocyte differentiation antigens are found in vitiligo and represent the effective anti-melanocyte reactivity that is often ineffective in melanoma.

TESTING THE HYPOTHESIS

Melanocyte-specific T cell clones can be isolated from the peripheral blood of vitiligo patients and tested for their capacity to efficiently expand in vitro without loosing their cytotoxic activity and to migrate to the skin. Cytotoxicity against melanoma patients' non-tumor cells can also be tested. In addition, it would be interesting to attempt an in vivo animal model. If the results obtained from these validation steps will be satisfactory, it might be possible to plan the clinical grade preparation of relevant clones for transfer.

IMPLICATIONS OF THE HYPOTHESIS

When translated into a clinical trial, the possibility of in vitro selecting few effective tumor-specific T cell clones for infusion, inherent with this approach, could enhance the therapeutic graft-versus-tumor effect while possibly decreasing the risk of graft-versus-host disease.

Anti-Tumor Antibodies in Ovarian Cancer

Anti-tumor antibodies have potential as cancer biomarkers. There is relatively limited identification of anti-tumor antibodies in response to ovarian cancer, compared with studies for other cancers. There is also very limited information on the prevalence of anti-tumor antibodies among ovarian cancer patients. Although most anti-tumor antibodies react with antigens common to both tumor and normal tissue, the anti-tumor response tends to be confined to individuals with ovarian cancer, similar to other cancers. Antibodies to HOXA7, a differentiation antigen, have the highest reported prevalence in ovarian cancer (67%). Antibodies to other ubiquitous antigens including NY-ESO-1, Ep-CAM (epithelial cell adhesion molecule), HSP-90 (heat shock protein 90), and mutated p53 have been identified in ovarian cancer. Anti-tumor antibody specificity reflects the heterogeneity of antigen expression in tumors. Tests based on panels of a combination of anti-tumor antibodies may be more predictive for ovarian cancer, as no single specificity accounts for ovarian tumors. In addition to characterization of anti-tumor antibodies as diagnostic markers, study of anti-tumor antibodies is likely to provide insights into mechanisms of tumor development. There is evidence of antibodies to tumor antigens and of activated T cells, suggesting immune recognition of tumor antigens occurred. Nonetheless, as tumors are not 'rejected', it is likely that there are alterations in the immune system. The basis for tumor growth in the face of immune activity remains to be determined.

Melanocyte-specific, cytotoxic T cell responses in vitiligo: the effective variant of melanoma immunity?

Vitiligo is a relatively common progressive depigmentary condition that is believed to be due to the autoimmune-mediated loss of epidermal melanocytes. An interesting aspect of vitiligo is its relation to melanoma: cytotoxic T lymphocytes directed to self-antigens shared by normal melanocytes and melanoma cells are found in both conditions and might prove important in melanocyte destruction, yet the resulting immune reactions are completely different. From this standpoint, the selective destruction of pigment cells that occurs in cases of vitiligo is the therapeutic goal sought in melanoma research. In the present article, we will address these issues by reviewing current literature on the subject as well as by posing some speculations.

Melanin pigmentation in mammalian skin and its hormonal regulation

Cutaneous melanin pigment plays a critical role in camouflage, mimicry, social communication, and protection against harmful effects of solar radiation. Melanogenesis is under complex regulatory control by multiple agents interacting via pathways activated by receptor-dependent and -independent mechanisms, in hormonal, auto-, para-, or intracrine fashion. Because of the multidirectional nature and heterogeneous character of the melanogenesis modifying agents, its controlling factors are not organized into simple linear sequences, but they interphase instead in a multidimensional network, with extensive functional overlapping with connections arranged both in series and in parallel. The most important positive regulator of melanogenesis is the MC1 receptor with its ligands melanocortins and ACTH, whereas among the negative regulators agouti protein stands out, determining intensity of melanogenesis and also the type of melanin synthesized. Within the context of the skin as a stress organ, melanogenic activity serves as a unique molecular sensor and transducer of noxious signals and as regulator of local homeostasis. In keeping with these multiple roles, melanogenesis is controlled by a highly structured system, active since early embryogenesis and capable of superselective functional regulation that may reach down to the cellular level represented by single melanocytes. Indeed, the significance of melanogenesis extends beyond the mere assignment of a color trait.

Autocrine and paracrine regulation of melanocytes in human skin and in pigmentary disorders

Recently melanogenic paracrine or autocrine cytokine networks have been discovered in vitro between melanocytes and other types of skin cells. These include endothelin (ET)-1, granulocyte macrophage colony stimulating factor, membrane-type stem cell factor (SCF) and growth-related oncogene-alpha for interactions between keratinocytes and melanocytes, and hepatocyte growth factor and soluble type SCF for interactions between fibroblasts and melanocytes. These networks are also associated with corresponding receptors expressed on melanocytes, including ET B receptor and the SCF receptor, c-KIT. Consistent with in vitro findings on the melanogenic paracrine or autocrine cytokine networks, we have found that the up- or down-regulation of such networks is intrinsically involved in vivo in the stimulation of melanocyte functions in several epidermal hyper- or hypo-pigmentary disorders. These are ET-1/ET B receptor as well as membrane type SCF/c-KIT for ultraviolet B-melanosis, granulocyte macrophage colony stimulating factor for ultraviolet A-melanosis, ET-1/ET B receptor as well as membrane type SCF for lentigo senilis, growth related oncogene-alpha for Riehl's melanosis, sphingosylphosphorylcholine for hyperpigmentation in atopic dermatitis, ET-1 for seborrhoeic keratosis, soluble type SCF as well as hepatocyte growth factor for dermatofibroma and café-au-lait macules, and c-KIT for vitiligo vulgaris. These unveiled regulatory mechanisms involved in the abnormal up- or down-regulated levels of lesional melanocyte function provide new insights into therapeutic tools utilizing blockage of responsible cytokine networks.