Networks of CD8+ T Cell Response Activation in Melanoma and Vitiligo

A Mendelian randomization study on the causal effects of circulating cytokines on the risk of vitiligo

Background

Accumulating evidence reveals an association between circulating cytokine levels and vitiligo. However, the causal association between circulating cytokine levels and vitiligo remains unrevealed.

Methods

We performed a two-sample Mendelian randomization (MR) analysis using a genome-wide association study of the 41 cytokines dataset, which was conducted with 3 Finnish cohorts (n = 8,293). Vitiligo data were acquired from strictly defined vitiligo data collected by FinnGenbiobank analysis, which included 207,613 European ancestors (131 vitiligo patients, 207,482 controls). The inverse-variance weighted (IVW) method, weighted median (WME), simple model, weighted model, and MR-Egger were used to determine the changes in vitiligo pathogenic cytokine taxa, followed by sensitivity analysis, including horizontal pleiotropy analysis. The MR Steiger test evaluated the strength of a causal association, and the leave-one-out method was used to assess the reliability of the results. The possibility of reverse causality was also investigated using a reverse MR study.

Results

We observed that rising IL-4 levels generated an enhanced probability of vitiligo in IVW (OR 2.72, 95%CI 1.19-6.22, p = 0.018). According to the results of the MR analysis, there were causal links between IL-4 and vitiligo. Results were steady after sensitivity and heterogeneity analyses.

Conclusion

Our research reveals that a genetically determined increased level of circulating IL-4 may be linked to a higher risk of developing vitiligo. The development of innovative treatment approaches (such as tofacitinib or dupilumab) that focus on blocking IL-4 as a novel way of preventing and treating vitiligo is significantly impacted by our findings.

Exosomes containing miR-1469 regulate natural killer cells by targeting CD122 in non-segmental vitiligo

BACKGROUND

Plasma exosomal microRNAs (miRNAs) have been used as potential biomarkers for various diseases and have been investigated for their possible involvement in the pathogenesis of vitiligo. However, the miRNA expression profile of plasma exosomes in patients with non-segmental vitiligo (NSV) has not been determined yet.

OBJECTIVE

To screen differentially expressed microRNAs in plasma exosomes derived from patients with NSV and explore their roles in the pathogenesis of NSV.

METHODS

High-throughput sequencing was performed to determine the expression profiles of exosomal miRNAs in NSV. The effect of upregulated miR-1469 in NSV circulating exosomes on natural killer (NK) cells was further investigated using various molecular biological techniques.

RESULTS

MiR-1469 was identified as a candidate biomarker whose expression was significantly increased in circulating exosomes of NSV patients. Circulating exosomes were internalized by NK cells and increased NK cell proliferation viability and IFN-γ secretion capacity delivering miR-1469. Further studies revealed that the upregulation of CD122, the predicted target of miR-1469, could partially reverse the effect of miR-1469 on natural killer cells.

CONCLUSION

Alterations in plasma exosomal cargo occur in NSV and appear to contribute to NK cell dysfunction. Exosomal miR-1469 may be a biomarker of disease activity and could be used as a therapeutic drug target against innate immunity in NSV patients. The present study provides new insights into the role of exosomal miRNAs in NSV and suggests a novel miR-1469-CD122-IFN-γ pathway of NK cell underlying pathogenesis of NSV.

Tumour regression predicts better response to interferon therapy in melanoma patients: a retrospective single centre study

We hypothesise that regression may have an impact on the effectiveness of adjuvant IFN therapy, based on its role in the host immune response. Our purpose is to investigate regression and ulceration as prognostic factors in case of interferon-alpha (IFN)-treated melanoma patients. We followed 357 IFN-treated melanoma patients retrospectively, investigating progression-free survival (PFS) and overall survival (OS) depending on the presence of ulceration and regression. A Kaplan-Meier analysis was performed, and we used a Cox regression analysis to relate risk factors. The survival function of the Cox regression was used to measure the effect of regression and ulceration on PFS and OS depending on the Breslow thickness (T1-T4) of the primary tumour. Regression was significantly positively related to PFS ( P  = 0.0018, HR = 0.352) and OS ( P  = 0.0112, HR = 0.380), while ulceration showed a negative effect (PFS: P  = 0.0001, HR = 2.629; OS: P  = 0.0003, HR = 2.388). They influence survival independently. The most favourable outcome was measured in the regressed/non-ulcerated group, whereas the worse was in the non-regressed/ulcerated one. Of risk factors, Breslow thickness is the most significant predictor. The efficacy of regression is regardless of Breslow thickness, though the more favourable the impact of regression was in the thicker primary lesions. Our results indicate that regression is associated with a more favourable outcome for IFN-treated melanoma patients, whereas ulceration shows an inverse relation. Further studies are needed to analyse the survival benefit of regression in relation to innovative immune checkpoint inhibitors.

Immune dysregulation and inflammation causing hypopigmentation in post kala-azar dermal leishmaniasis: partners in crime?

Post kala-azar dermal leishmaniasis (PKDL), a heterogeneous dermal sequela of visceral leishmaniasis (VL), is challenging in terms of its etiopathogenesis. Hypopigmentation is a consistent clinical feature in PKDL, but mechanisms contributing to the loss of melanocytes remains poorly defined. Like other hypopigmentary dermatoses - for example, vitiligo, psoriasis, and leprosy - the destruction of melanocytes is likely a multifactorial phenomenon, key players being immune dysregulation and inflammation. This review focuses on immunological mechanisms responsible for the 'murder' of melanocytes, prime suspects at the lesional sites being CD8+ T cells and keratinocytes and their criminal tools being proinflammatory cytokines, for example, IFN-γ, IL-6, and TNF-α. Collectively, these may cause decreased secretion of melanocyte growth factors, loss/attenuation of cell adhesion molecules and inflammasome activation, culminating in melanocyte death.

Ubiquitin-specific protease 34 in macrophages limits CD8 T cell-mediated onset of vitiligo in mice

As an autoimmune disorder, vitiligo is characterized by depigmented skin macules. CD8⁺T cells and macrophages enrichment promote the onset of vitiligo, while the role of macrophages to CD8⁺T is not well deciphered. To develop a mouse model of vitiligo with prominent epidermal depigmentation, Krt14-Kitl* transgenic mice containing an elevated number of melanocytes in the epidermis with membrane-bound Kit ligand (Kitl*) were adoptively transferred with premelanosome protein (PMEL) CD8⁺ T cells. On the other hand, Krt14-Kitl* mice were mated with ubiquitin-specific protease 34 (USP34)^MKO mice to decipher the role of USP34 in vitiligo. Vitiligo scores and PMEL CD8⁺ T cell enrichment were detected with flow cytometry. Human peripheral blood mononuclear cells (PBMCs) or mice bone marrow-derived macrophages (BMDMs) were incubated with lipopolysaccharide (LPS), CpG, or co-incubated with KU-55933, an ataxia telangiectasia-mutated (ATM) inhibitor. Chemokine (C-C motif) ligand 2 (CCL2), Ccl5, and interleukin (Il)-12α expression was assayed with real-time PCR, and p-IKKα/β was assayed with Western blots. USP34 was up-regulated in the PBMCs of vitiligo patients and LPS-stimulated BMDMs. USP34 deficiency did not affect the differentiation of CD11b⁺F4/80⁺ macrophages in the bone marrow. Immunoprecipitation demonstrated the interaction between USP34 and ATM. USP34 deficiency or KU-55933 administration promoted the induction of Ccl2, Ccl5, Il12α, and p-IKKα/β in LPS or CpG stimulated BMDMs; KU-55933 administration could not affect the expression of the above molecules in USP34 deficient BMDMs. It further revealed that USP34 deficiency promoted the development of vitiligo with increased PMEL CD8⁺ T cell enrichment, which was not affected by KU-55933 administration. USP34 deficiency in macrophages promotes the onset of vitiligo with increased PMEL CD8⁺ T cell enrichment, and USP34/ATM complex can be considered as a therapy target.

Regression in cutaneous melanoma: histological assessment, immune mechanisms and clinical implications

Tumour regression is an immunologically driven process that results in complete or partial disappearance of tumour cells. This can be observed in histological sections as replacement of tumour cells with fibrosis, angiogenesis, and a variable inflammatory infiltrate. In primary cutaneous melanoma, the prognostic significance of regression has been debated for decades, in part because inconsistent histological criteria are used in prognostication studies. It is broadly accepted that CD8+ T lymphocytes are the primary effectors of the anti-tumour response, but the interplay between melanoma and the immune system is complex, dynamic, and incompletely understood. Sustained progress in unravelling the pathogenesis of melanoma regression has led to the identification of therapeutic targets, culminating in the development of immune checkpoint inhibitors for the management of advanced disease. Modern techniques allow for high-resolution spatial analyses of the tumour microenvironment. Such studies may lead to better understanding of the immune drivers of melanoma regression, thereby facilitating the search for new prognostic and predictive biomarkers to assist clinical decision-making.

Does immune dysregulation contribute towards development of hypopigmentation in Indian post kala-azar dermal leishmaniasis?

Post kala-azar dermal leishmaniasis (PKDL), a sequel of apparently cured visceral leishmaniasis (VL) presents with papulonodular (polymorphic) or hypopigmented lesions (macular) and is the proposed disease reservoir. As hypopigmentation appears consistently in PKDL, especially the macular form, this study aimed to delineate immune factors that singly or in combination could contribute towards this hypopigmentation. At lesional sites, the presence of melanocytes and CD8⁺ T-cells was assessed by immunohistochemistry and mRNA expression of melanogenic markers (tyrosinase, tyrosinase-related protein-1 and MITF) by droplet digital PCR, while plasma levels of cytokines and chemokines were measured by a multiplex assay. In comparison with skin from healthy individuals, macular PKDL demonstrated a near total absence of Melan-A⁺ cells at dermal sites, while the polymorphic cases demonstrated a 3.2-fold decrease, along with a dramatic reduction in the expression of key enzymes related to the melanogenesis signalling pathway in both forms. The levels of circulating IFN-γ, IL-6, IL-2, IL-1β, TNF-α and IFN-γ-inducible chemokines (CXCL9/10/11) were elevated and was accompanied by an increased lesional infiltration of CD8⁺ T-cells. The proportion of CD8⁺ T-cells correlated strongly with plasma levels of IFN-γ (r = 0.8), IL-6 (r = 0.9, p < 0.05), IL-2 (r = 0.7), TNF-α (r = 0.9, p < 0.05) and IL-1β (r = 0.7), as also with CXCL9 (r = 0.5) and CXCL10 (r = 0.6). Taken together, the absence/reduction in Melan-A suggested hypopigmentation in PKDL was associated with the destruction of melanocytes, following the impairment of the melanogenesis pathway. Furthermore, the presence of CD8⁺ T-cells and an enhanced IFN-γ-associated immune milieu suggested the generation of a pro-inflammatory landscape that facilitated melanocyte dysfunction/destruction.

Vitiligo: An immune disease and its emerging mesenchymal stem cell therapy paradigm

Melanocyte damage, innate immune response, adaptive immune response, and immune inflammatory microenvironment disorders are involved in the development of the immunological pathogenic mechanism of vitiligo. Mesenchymal stem cells are considered an ideal type of cells for the treatment of vitiligo owing to their low immunogenicity, lower rates of transplant rejection, and ability to secrete numerous growth factors, exosomes, and cytokines in vivo. The regulation of signaling pathways related to oxidative stress and immune imbalance in the immunological pathogenesis of vitiligo can improve the immune microenvironment of tissue injury sites. In addition, co-transplantation with melanocytes can reverse the progression of vitiligo. Therefore, continuous in-depth research on the immunopathogenic mechanism involved in this disease and mesenchymal stem cell-based therapy is warranted for the treatment of vitiligo in the future.

Immunotherapy for Melanoma: The Significance of Immune Checkpoint Inhibitors for the Treatment of Advanced Melanoma

Therapeutic options for treating advanced melanoma have progressed rapidly in recent decades. Until 6 years ago, the regimen for treating advanced melanoma consisted mainly of cytotoxic agents such as dacarbazine and type I interferons. Since 2014, anti-programmed cell death 1 (PD1) antibodies have been recognized as anchor drugs for treating advanced melanoma, with or without additional combination drugs such as ipilimumab, but the efficacies of these immunotherapies are not fully satisfactory. In this review, we describe the development of the currently available anti-PD1 Abs-based immunotherapies for advanced melanoma, focusing on their efficacy and immune-related adverse events (AEs), as well as clinical trials still ongoing for the future treatment of advanced melanoma.

A CD8+ T cell-associated immune gene panel for prediction of the prognosis and immunotherapeutic effect of melanoma

Background

Skin cutaneous melanoma (SKCM) is the most frequently encountered tumor of the skin. Immunotherapy has opened a new horizon in melanoma treatment. We aimed to construct a CD8⁺ T cell-associated immune gene prognostic model (CDIGPM) for SKCM and unravel the immunologic features and the benefits of immunotherapy in CDIGPM-defined SKCM groups.

Method

Single-cell SKCM transcriptomes were utilized in conjunction with immune genes for the screening of CD8⁺ T cell-associated immune genes (CDIGs) for succeeding assessment. Thereafter, through protein-protein interaction (PPI) networks analysis, univariate COX analysis, and multivariate Cox analysis, six genes (MX1, RSAD2, IRF2, GBP2, IFITM1, and OAS2) were identified to construct a CDIGPM. We detected cell proliferation of SKCM cells transfected with IRF2 siRNA. Then, we analyzed the immunologic features and the benefits of immunotherapy in CDIGPM-defined groups.

Results

The overall survival (OS) was much better in low-CDIGPM group versus high CDIGPM group in TCGA dataset and GSE65904 dataset. On the whole, the results unfolded that a low CDIGPM showed relevance to immune response-correlated pathways, high expressions of CTLA4 and PD-L1, a high infiltration rate of CD8⁺ T cells, and more benefits from immunotherapy.

Conclusion

CDIGPM is an good model to predict the prognosis, the potential immune escape from immunotherapy for SKCM, and define immunologic and molecular features.