Project description:Halo nevi are clinically common and are characterized by a circle of leukoderma around the central melanocytic nevus. Studies have shown that the pathogenesis of the surrounding leukoderma is similar to that of vitiligo and is associated with the role of CD8⁺ T lymphocytes in melanocyte destruction. Notably, some halo nevi exhibit a tendency for spontaneous regression of the surrounding leukoderma, yet the underlying mechanisms remain unclear. Furthermore, histopathological findings have revealed neutrophil infiltration in halo nevi, but the specific immune mechanisms involving neutrophils have not been thoroughly investigated. This study investigated the role of neutrophils in halo nevi through histopathological and immunological analyses, aiming to provide some clues for identifying the mechanisms underlying the regression of surrounding leukoderma. We examined the infiltration patterns of immune cells in halo nevi, with a particular focus on IFN-γ-induced PD-L1 expression in neutrophils and its potential immunoregulatory effects. The results demonstrated that IFN-γ expression in the lesional skin of halo nevi contributed to the induction of PD-L1 expression in neutrophils. PD-L1⁺ neutrophils promoted apoptosis and suppressed the function of CD8⁺ T lymphocytes. This regulatory mechanism influences the local immune response and may facilitate the repigmentation of the surrounding leukoderma. This study is the first to explore the involvement mechanism of neutrophils in halo nevi and to reveal the potential immunoregulatory role of PD-L1. The elucidation of this mechanism not only provides a more comprehensive understanding of autoimmune skin diseases but may also offer new strategies for targeted therapy in related pigmentary disorders, such as vitiligo.
Project description:Human CD4+ T cells mediate spontaneous rejection of acquired benign melanocytic nevi, in the majority of cases, through a break in peripheral tolerance. For the remaining cases, nevi remain stable and do not progress to malignancy. In this experiment, we compared gene expression of post-transplant rejected nevi to stable nevi in order to better characterize their transcriptional profiles.
Project description:The dysregulated host response to infections can lead to sepsis, a complex disease characterized by a spectrum of clinical phenotypes associated with the host immune response variability and outcomes. This heterogeneity poses challenges for implementing specific therapeutic approaches. While clinical sepsis phenotypes are well distinguished, the mechanisms driving these heterogeneous responses remain poorly understood. Using an unbiased experimental approach, we analysed immune cell activation profiles in survived and non-survived CLP-septic to gain insights into the immunological mechanisms by which neutrophils contribute to the hyperinflammatory septic phenotype. Our finds reveal that non-survived septic mice exhibit increased frequencies of immature CXCR4+ PD-L1+ neutrophils and monocytes in the bloodstream, accompanied by an accumulation of trafficking-specific CXCR4+ PD-L1+ neutrophils into the lungs. The increased PD-L1 expression on CXCR4+ neutrophils is associated with increase of IFN-gamma signaling pathways. Additionally, the IFN-gamma and LPS promote an activation profile of CXCR4+ PD-L1+ neutrophils, exhibiting a phenotype associated with inflammation and organ damage. Notably, abrogating the IFN-gamma reduced susceptibility to CLP-sepsis and diminished PD-L1 expression on CXCR4+ neutrophils. This study provides molecular and functional insights into the immune cell activation profiles associated with the worsening of the septic hyperinflammatory phenotype experimental model. The CXCR4+ PD-L1+ neutrophils population and elevated plasmatic IFN-gamma levels highlighted here represent promising targets for therapeutic modulation in clinical sepsis hyperinflammatory phenotype.
Project description:The purpose of this study was to comprehensively study and compare the molecular gene expression profiles of common melanocytic nevi (GSE53223), dysplastic nevi (GSE53223), and primary melanoma.
Project description:We have developed Halo-seq, an RNA proximity labeling method that allows the quantification of subcellular transcriptomes. We have demonstrated the efficacy of Halo-seq here by using it to quantify chromatin-proximal, nucleolar, and cytoplasmic transcriptomes. In Halo-seq, RNA molecules in close proximity to a spatially restricted protein are specifically marked and biotinylated, facilitating their separation from bulk cellular RNA and their quantification.
Project description:The molecular properties of benign melanocytic lesions are poorly understood. Only few studies have been performed on specific nevi subtypes, including common nevocellular nevi (NCN) or Spitz nevi (SN). Genomic alterations in melanoma-associated oncogenes are typically absent in SN. In the present study, mRNA expression of 25 SN and 15 NCN were analyzed. Molecular profiling was done using the RNA NanoString nCounter Gene Expression Platform (No. of genes = 770). Marker discovery was performed with a training set consisting of 7 SN and 7 NCN samples from the same patients, and validation was performed using a second set consisting of 18 SN and 8 NCN samples. Using the training set, 197 differentially expressed genes were identified in SN versus NCN. Of these, 74 genes validated in the validation set (FDR Q value ≤ 0.13). In addition, using Random Forest and LASSO feature selection a molecular signature of SN versus NCN was identified including 15 top-ranked genes. Gene set analysis showed upregulation of gene pathways with increased expression of transcripts related to immunomodulatory, inflammatory and extracellular matrix interactions as well as angiogenesis associated processes in SN. Although the molecular characteristics of malignant melanoma have been studied in detail, the molecular properties of benign melanocytic lesions such as common nevocellular nevi (NCN) and Spitz nevi (SN) remain poorly understood. This limited knowledge hinders a better understanding of atypical and malignant transformation of melanocytes. The present study identified a distinct molecular expression profile in SN compared to NCN, even when lesions were obtained from the same patients. These findings strongly indicate that SN represent a distinct group of melanocytic neoplasms and evolve differentially and not sequentially from NCN.
Project description:BAP1 inactivation, observed across multiple human cancers, is linked to immune checkpoint blockade (ICB) resistance and adverse clinical outcomes. The mechanisms underlying BAP1-associated ICB sensitivity could provide potential targets to enhance ICB efficacy. Here, we showed that BAP1 inactivation fosters an immunosuppressive tumor microenvironment (TME), marked by increased infiltration of M2-like macrophages and neutrophils. Single-cell transcriptomic analysis revealed an expansion of SPP1+ neutrophils in ICB-treated, BAP1-inactivated tumors. These SPP1+ neutrophils displayed a pro-tumorigenic phenotype and conferred resistance to anti-PD-1 therapy by engaging with cytotoxic T cells via PD-1/PD-L1 signaling. Notably, depletion of neutrophils, but not macrophages, restored sensitivity to ICB in BAP1-inactivated tumors. Mechanistically, BAP1 loss significantly increased CCL2 secretion, driving neutrophil SPP1+ polarization, delaying neutrophil apoptosis, and promoting ICB resistance. This resistance could be significantly mitigated by targeting the CCL2-CCR2 axis. These results underscore the role of BAP1 in modulating the immune landscape and suggest that targeting CCL2-CCR2-mediated neutrophil polarization may overcome ICB resistance in BAP1-inactivated tumors.
Project description:A substantial part of cutaneous malignant melanomas develops from benign nevi. However, the precise molecular events driving the transformation from benign to malignant melanoma are not well understood. We used laser microdissection and mass spectrometry to analyze the proteomes of melanoma subtypes, including superficial spreading melanomas (SSM, n=17), nodular melanomas (NM, n=17), and acral melanomas (AM, n=15). Furthermore, we compared the proteomes of nevi cells and melanoma cells within the same specimens (nevus-associated melanoma (NAM, n=14)). In total, we quantified 7,935 proteins. Despite the genomic and clinical differences of the melanoma subtypes, our analysis revealed relatively similar proteomes, except for the upregulation of proteins involved in immune activation in NM vs AM. Examining NAM versus nevi, we found 1,725 differentially expressed proteins. Among these proteins were 140 that overlapped with cancer hallmarks, tumor suppressors, and regulators of metabolism and cell cycle. Pathway analysis indicated aberrant activation of the RAS/MAPK and PI3K-AKT-mTOR pathways, as well as the Hippo-YAP pathway. Using a classifier, we identified six proteins capable of distinguishing melanoma from nevi samples. Our study represents the first comprehensive comparative analysis of the proteome in melanoma subtypes and associated nevi, offering new insights into the biological behavior of these distinct entities.