Enhancement of anti-tumor activity in vitro and in vivo by CD150 and SAP

SLAM family-mediated crosstalk between tumor and immune cells in the tumor microenvironment: a promising biomarker and a potential therapeutic target for immune checkpoint therapies

Immune cells infiltrating the tumor microenvironment are physiologically important in controlling cancers. However, emerging studies have shown that cancer cells can evade immune surveillance and establish a balance in which these immune cells support tumor progression and therapeutic resistance. The signaling lymphocytic activation molecule family members have been recognized as mediators of tumor microenvironment interactions, and a promising therapeutic target for cancer immunotherapy. This review is focused on the role of SLAM family in tumor and immune cell interactions and discusses how such crosstalk affects tumor behavior. This will shed insight into the next step toward improving cancer immunotherapy.

Signaling lymphocytic activation molecule family receptors as potential immune therapeutic targets in solid tumors

Recently, cancer immunotherapy has revolutionized cancer treatment. Various forms of immunotherapy have a manageable safety profile and result in prolongation of overall survival in patients with solid tumors, but only in a proportion of patients. Various factors in the tumor microenvironment play critical roles and may be responsible for this lack of therapeutic response. Signaling lymphocytic activation molecule family (SLAMF) members are increasingly being studied as factors impacting the tumor immune microenvironment. SLAMF members consist of nine receptors mainly expressed in immune cells. However, SLAMF receptors have also been detected in cancer cells, and they may be involved in a spectrum of anti-tumor immune responses. Here, we review the current knowledge of the expression of SLAMF receptors in solid tumors and tumor-infiltrating immune cells and their association with patient outcomes. Furthermore, we discuss the therapeutic potential of targeting SLAMF receptors to improve outcomes of cancer therapy in solid tumors. We believe the research on SLAMF receptor-targeted strategies may enhance anti-cancer immunity in patients with solid tumors and improve clinical outcomes.

Heterogeneity in the Metastatic Microenvironment: JunB-Expressing Microglia Cells as Potential Drivers of Melanoma Brain Metastasis Progression

Reciprocal signaling between melanoma brain metastatic (MBM) cells and microglia reprograms the phenotype of both interaction partners, including upregulation of the transcription factor JunB in microglia. Here, we aimed to elucidate the impact of microglial JunB upregulation on MBM progression. For molecular profiling, we employed RNA-seq and reverse-phase protein array (RPPA). To test microglial JunB functions, we generated microglia variants stably overexpressing JunB (JunBhi) or with downregulated levels of JunB (JunBlo). Melanoma-derived factors, namely leukemia inhibitory factor (LIF), controlled JunB upregulation through Janus kinase (JAK)/signal transducer and activator of transcription 3 (STAT3) signaling. The expression levels of JunB in melanoma-associated microglia were heterogeneous. Flow cytometry analysis revealed the existence of basal-level JunB-expressing microglia alongside microglia highly expressing JunB. Proteomic profiling revealed a differential protein expression in JunBhi and JunBlo cells, namely the expression of microglia activation markers Iba-1 and CD150, and the immunosuppressive molecules SOCS3 and PD-L1. Functionally, JunBhi microglia displayed decreased migratory capacity and phagocytic activity. JunBlo microglia reduced melanoma proliferation and migration, while JunBhi microglia preserved the ability of melanoma cells to proliferate in three-dimensional co-cultures, that was abrogated by targeting leukemia inhibitory factor receptor (LIFR) in control microglia-melanoma spheroids. Altogether, these data highlight a melanoma-mediated heterogenous effect on microglial JunB expression, dictating the nature of their functional involvement in MBM progression. Targeting microglia highly expressing JunB may potentially be utilized for MBM theranostics.

Immune Subtypes and Immune Landscape Analysis of Endometrial Carcinoma

Some patients with endometrial cancer (EC) suffer from limited survival benefits after immunotherapy, suggesting that there may be a specific pattern associated with immunotherapy. Immune-related genes were extracted from The Cancer Genome Atlas databases. We analyzed the differences among immune subtypes (ISs) in the distribution of the tumor mutational burden, chemotherapy-induced immune response markers, immune checkpoint-related genes, immunotherapy, and chemotherapy. We applied dimensionality reduction and defined the immune landscape of EC. Then, we used the Weighted Gene Co-Expression Network Analysis package to identify the coexpression modules of these immune genes. Finally, hub genes were selected and detected by quantitative PCR and immunohistochemistry. We obtained three ISs. There were differences in the distribution of the tumor mutational burden, chemotherapy-induced immune response markers, and immune checkpoint-related genes among the ISs. Regarding immunotherapy and chemotherapy, the IS2 subtypes were more sensitive to programmed cell death protein 1 inhibitors. In addition, different positions in the immune landscape map exhibited different prognostic characteristics, providing further evidence of the ISs. The IS2 subtypes were significantly positively correlated with yellow module gene list, indicating a good prognosis with high score. SIRPG and SLAMF1 were identified as the final characteristic genes. The quantitative PCR and immunohistochemistry results showed that the expression levels of SIRPG and SLAMF1 were low in human EC tissue. In this study, we identified three reproducible ISs of EC. The immune landscape analysis further revealed the intraclass heterogeneity of the ISs. SIRPG and SLAMF1 were identified to be associated with progression, suggesting that they may be novel immune-related biomarkers of EC.

Inflammatory patterns in plasma associate with hepatocellular carcinoma development in cured hepatitis C cirrhotic patients

Introduction

The risk of hepatocellular carcinoma persists in some patients despite achieving sustained virologic response with current interferon‐free direct‐acting antiviral therapy for hepatitis C. The subject of an even higher carcinoma risk in this context has been reported and is currently being debated. The quest for understanding this paradox relative to the dynamics of inflammatory biomarkers in cirrhosis patients receiving antiviral therapy thus remains a subject of importance.

Objective

Here, we aimed at evaluating the effects of direct‐acting antiviral therapy‐induced hepatitis C cure on plasmatic markers of systemic inflammation measured before, during and after treatment. Specifically, soluble immune mediator phenotype associations that impact the odds of hepatocellular carcinoma development and the related changes that arise upon direct‐acting antiviral‐mediated hepatitis C clearance in cirrhosis patients was investigated.

Methods

Employing multiplex technology that measured up to 91 circulating biomarker proteins, we profiled the plasma soluble immune mediator concentrations of cirrhosis patients who developed posttreatment hepatocellular carcinoma and their respective negative controls, before and after direct‐acting antiviral treatment.

Results

Elevated pretherapy concentrations of specific soluble immune mediators including MCP‐3, GDNF, CDCP1, IL‐17C, IL‐17A, signalling lymphocytic activation family 1, CCL11, FGF‐5, LIF‐R, interleukin 10 (IL‐10), IL‐10RA, IL‐15RA, beta NGF, CCL28, CCL25 and NT‐3 distinguished patients who developed posttreatment hepatocellular carcinoma relative to those that did not. Particularly, GDNF, FGF‐5 and IL‐15RA displayed independent predictive biomarker attributes for delineating carcinoma emergence regardless of de novo or recurrence groupings. Upon successful therapy, the elevated pretherapy soluble immune mediator establishment of the patients who eventually developed hepatocellular carcinoma stayed largely unperturbed whereas a panel of some 38 soluble immune mediators in the posttherapy carcinoma‐free patients experienced significant ameliorations.

Conclusions

These results have considerable implications for delineating potential hepatocellular carcinoma emergence before initiating direct‐acting antiviral therapy for hepatitis C in cirrhosis patients. They provide preliminary contribution to unravelling cases where the benefit of direct‐acting antiviral therapies would be superior to the risk of developing carcinoma.

Established knowledge on this subject

Current interferon (IFN)‐free direct‐acting antivirals (DAAs) are effective at eliminating hepatitis C virus (HCV), but risks of residual liver disease and development of hepatocellular carcinoma persists.

The hepatic inflammation that occurs during chronic hepatitis C causes systemic changes in blood soluble immune mediators (SIMs) that impact carcinogenetic processes involved in the growth, invasion and metastasis of hepatocellular carcinoma (HCC).

DAA‐induced HCV cure does not lead to a complete immunological restitution of the altered soluble inflammatory compartment in chronic hepatitis C.

Significant and/or new findings of this study

An elevated pre‐therapy plasma profile of an extended repertoire of SIMs in cirrhosis was associated with HCC development post‐DAA therapy.

Successful DAA therapy did not alter the baseline elevated plasma SIM profile of cirrhosis patients that developed post‐therapy HCC contrary to its effect in those that remained HCC‐free.

SLAMF1/CD150 in hematologic malignancies: Silent marker or active player?

SLAMF1/CD150 receptor is a founder of signaling lymphocyte activation molecule (SLAM) family of cell-surface receptors. It is widely expressed on cells within hematopoietic system. In hematologic malignancies CD150 cell surface expression is restricted to cutaneous T-cell lymphomas, few types of B-cell non-Hodgkin's lymphoma, near half of cases of chronic lymphocytic leukemia, Hodgkin's lymphoma, and multiple myeloma. Differential expression among various types of hematological malignancies allows considering CD150 as diagnostical and potential prognostic marker. Moreover, CD150 may be a target for antibody-based or measles virus oncolytic therapy. Due to CD150 signaling properties it is involved in regulation of malignant cell fate decision and tumor microenvironment in Hodgkin's lymphoma and chronic lymphocytic leukemia. This review summarizes evidence for the important role of CD150 in pathogenesis of hematologic malignancies.

Signaling lymphocytic activation molecules Slam and cancers: friends or foes?

Signaling Lymphocytic Activation Molecules (SLAM) family receptors are initially described in immune cells. These receptors recruit both activating and inhibitory SH2 domain containing proteins through their Immunoreceptor Tyrosine based Switch Motifs (ITSMs). Accumulating evidence suggest that the members of this family are intimately involved in different physiological and pathophysiological events such as regulation of immune responses and entry pathways of certain viruses. Recently, other functions of SLAM, principally in the pathophysiology of neoplastic transformations have also been deciphered. These new findings may prompt SLAM to be considered as new tumor markers, diagnostic tools or potential therapeutic targets for controlling the tumor progression. In this review, we summarize the major observations describing the implications and features of SLAM in oncology and discuss the therapeutic potential attributed to these molecules.

Signals Controlling Lytic Granule Polarization at the Cytotoxic Immune Synapse

Cytotoxic immunity relies on specialized effector T cells, the cytotoxic T cells, which are endowed with specialized cytolytic machinery that permits them to induce death of their targets. Upon recognition of a target cell, cytotoxic T cells form a lytic immune synapse and by docking the microtubule-organizing center at the synaptic membrane get prepared to deliver a lethal hit of enzymes contained in lytic granules. New insights suggest that the directionality of lytic granule trafficking along the microtubules represents a fine means to tune the functional outcome of the encounter between a T cell and its target. Thus, mechanisms regulating the directionality of granule transport may have a major impact in settings characterized by evasion from the cytotoxic response, such as chronic infection and cancer. Here, we review our current knowledge on the signaling pathways implicated in the polarized trafficking at the immune synapse of cytotoxic T cells, complementing it with information on the regulation of this process in natural killer cells. Furthermore, we highlight some of the parameters which we consider critical in studying the polarized trafficking of lytic granules, including the use of freshly isolated cytotoxic T cells, and discuss some of the major open questions.

Positive and negative regulation of cellular immune responses in physiologic conditions and diseases

The immune system has evolved to allow robust responses against pathogens while avoiding autoimmunity. This is notably enabled by stimulatory and inhibitory signals which contribute to the regulation of immune responses. In the presence of a pathogen, a specific and effective immune response must be induced and this leads to antigen-specific T-cell proliferation, cytokines production, and induction of T-cell differentiation toward an effector phenotype. After clearance or control of the pathogen, the effector immune response must be terminated in order to avoid tissue damage and chronic inflammation and this process involves coinhibitory molecules. When the immune system fails to eliminate or control the pathogen, continuous stimulation of T cells prevents the full contraction and leads to the functional exhaustion of effector T cells. Several evidences both in vitro and in vivo suggest that this anergic state can be reverted by blocking the interactions between coinhibitory molecules and their ligands. The potential to revert exhausted or inactivated T-cell responses following selective blocking of their function made these markers interesting targets for therapeutic interventions in patients with persistent viral infections or cancer.

Increased expression of SLAM receptors SLAMF3 and SLAMF6 in systemic lupus erythematosus T lymphocytes promotes Th17 differentiation

Altered T cell function in systemic lupus erythematosus (SLE) is determined by various molecular and cellular abnormalities, including increased IL-17 production. Recent evidence suggests a crucial role for signaling lymphocyte activation molecules (SLAMs) in the expression of autoimmunity. In this study, we demonstrate that SLAMF3 and SLAMF6 expression is increased on the surface of SLE T cells compared with normal cells. SLAM coengagement with CD3 under Th17 polarizing conditions results in increased IL-17 production. SLAMF3 and SLAMF6 T cell surface expression and IL-17 levels significantly correlate with disease activity in SLE patients. Both naive and memory CD4(+) T cells produce more IL-17 in response to SLAM costimulation as compared with CD28 costimulation. In naive CD4(+) cells, IL-17 production after CD28 costimulation peaks on day 3, whereas costimulation with anti-SLAMF3 and anti-SLAMF6 Abs results in a prolonged and yet increasing production during 6 d. Unlike costimulation with anti-CD28, SLAM costimulation requires the presence of the adaptor molecule SLAM-associated protein. Thus, engagement of SLAMF3 and SLAMF6 along with Ag-mediated CD3/TCR stimulation represents an important source of IL-17 production, and disruption of this interaction with decoy receptors or blocking Abs should mitigate disease expression in SLE and other autoimmune conditions.

SLAM family receptors and SAP adaptors in immunity

The signaling lymphocyte activation molecule (SLAM)-associated protein, SAP, was first identified as the protein affected in most cases of X-linked lymphoproliferative (XLP) syndrome, a rare genetic disorder characterized by abnormal responses to Epstein-Barr virus infection, lymphoproliferative syndromes, and dysgammaglobulinemia. SAP consists almost entirely of a single SH2 protein domain that interacts with the cytoplasmic tail of SLAM and related receptors, including 2B4, Ly108, CD84, Ly9, and potentially CRACC. SLAM family members are now recognized as important immunomodulatory receptors with roles in cytotoxicity, humoral immunity, autoimmunity, cell survival, lymphocyte development, and cell adhesion. In this review, we cover recent findings on the roles of SLAM family receptors and the SAP family of adaptors, with a focus on their regulation of the pathways involved in the pathogenesis of XLP and other immune disorders.

Gene profile analysis of CD8(+) ILT3-Fc induced T suppressor cells

Gene profile analysis of ILT3-Fc-induced Ts revealed a significant upregulation of Zink finger proteins, most of which act as transcriptional repressors. Included among these repressors is BCL6, which was shown to play a critical role in the differentiation of ILT3-Fc-induced T suppressor (Ts) cells. Genes implicated in cell cycle progression were downregulated. Genes encoding numerous inflammatory cytokines and chemokines were also downregulated. In contrast, antiapoptotic genes, as well as members of the WNT and transforming growth factor-β pathways, were upregulated. This study elucidates certain important aspects of Ts differentiation and function.

Induction of membrane ceramides: a novel strategy to interfere with T lymphocyte cytoskeletal reorganisation in viral immunosuppression

Silencing of T cell activation and function is a highly efficient strategy of immunosuppression induced by pathogens. By promoting formation of membrane microdomains essential for clustering of receptors and signalling platforms in the plasma membrane, ceramides accumulating as a result of membrane sphingomyelin breakdown are not only essential for assembly of signalling complexes and pathogen entry, but also act as signalling modulators, e. g. by regulating relay of phosphatidyl-inositol-3-kinase (PI3K) signalling. Their role in T lymphocyte functions has not been addressed as yet. We now show that measles virus (MV), which interacts with the surface of T cells and thereby efficiently interferes with stimulated dynamic reorganisation of their actin cytoskeleton, causes ceramide accumulation in human T cells in a neutral (NSM) and acid (ASM) sphingomyelinase-dependent manner. Ceramides induced by MV, but also bacterial sphingomyelinase, efficiently interfered with formation of membrane protrusions and T cell spreading and front/rear polarisation in response to beta1 integrin ligation or alphaCD3/CD28 activation, and this was rescued upon pharmacological or genetic ablation of ASM/NSM activity. Moreover, membrane ceramide accumulation downmodulated chemokine-induced T cell motility on fibronectin. Altogether, these findings highlight an as yet unrecognised concept of pathogens able to cause membrane ceramide accumulation to target essential processes in T cell activation and function by preventing stimulated actin cytoskeletal dynamics.

Ex vivo expanded telomerase-specific T cells are effective in an orthotopic mouse model for pancreatic adenocarcinoma

Telomerase activity is over-expressed in nearly all pancreatic carcinomas, but not in chronic pancreatitis. Here, we investigated various protocols for expansion of telomerase-specific T cells for adoptive cell transfer and their use in a syngeneic pancreatic carcinoma mouse model. Telomerase-specific T cells were generated by stimulation of splenocytes from peptide-immunized donor mice with either interleukin (IL)-2, IL-15, artificial antigen-presenting cells, anti-signalling lymphocyte activation molecule (SLAM) microbeads or allogeneic dendritic cells in combination with a limited dilution assay. T cells were tested for antigen specificity in vitro and for anti-tumour activity in syngeneic mice with orthotopically implanted tumours pretreated with cyclophosphamide. The immune cells from recipients were immunophenotyped. During a period of 2 weeks, the expansion approach using IL-2 was very successful in generating a high number of telomerase-specific CD8(+) T cells without losing their function after adoptive cell transfer. Significantly slower tumour growth rate and less metastasis were observed after adoptively transferring telomerase specific CD8(+) T cells, expanded using IL-2. Further investigations showed that anti-tumour efficacy was associated with a significant shift from naive CD8(+) T cells to CD8(+) central memory T cells, as well as recruitment of a high number of dendritic cells. Remarkable amounts of telomerase-specific T cells were detectable in the tumour. Generation of telomerase-specific T cells is feasible, whereat IL-2-based protocols seemed to be most effective and efficient. Antigen-specific T cells showed significant cytotoxic activity in a syngeneic, orthotopic mouse model, whereas central memory T cells but not effector memory T cells appear to be of high importance.

X-linked lymphoproliferative disease (XLP): a model of impaired anti-viral, anti-tumor and humoral immune responses

A major focus of our research is to understand the molecular and cellular basis of X-linked lymphoproliferative disease (XLP), a rare and often fatal immunodeficiency caused by mutations in the SH2D1A gene, which encodes the adaptor molecule SAP. Recently, we observed that SAP is essential for the development of natural killer T (NKT) cells, a lymphocyte population that participates in protection against certain tumors, infections, and autoimmune states. In this review, we describe the approaches that we are taking to understand the role of SAP in immune cells, including NKT cells. By using SAP as the focal point of our studies, we hope to identify novel signaling pathways that could be targeted to improve the treatment for patients with XLP as well as more common disorders, such as autoimmunity and cancer.

Angiostatic immune reaction in colorectal carcinoma: Impact on survival and perspectives for antiangiogenic therapy

Angiogenesis and inflammation are the 2 major stroma reactions in colorectal carcinoma (CRC). Guanylate binding protein-1 (GBP-1) is a key mediator of angiostatic effects of inflammation. Therefore, we hypothesized that GBP-1 may be a biomarker of intrinsic angiostasis associated with an improved outcome in CRC patients. GBP-1 was strongly expressed in endothelial cells and immune cells in the desmoplastic stroma of 32% of CRC as determined by immunohistochemical investigation of 388 sporadic CRC. Cancer-related 5-year survival was highly significant (p < 0.001) increased (16.2%) in patients with GBP-1-positive CRC. Multivariate analysis showed that GBP-1 is an independent prognostic factor indicating a reduction of the relative risk of cancer-related death by the half (p = 0.032). A comparative transcriptome analysis (22,215 probe sets) of GBP-1-positive (n = 12) and -negative (n = 12) tumors showed that particularly IFN-gamma-induced genes including the major antiangiogenic chemokines CXCL9, CXCL10 and CXCL11 were coexpressed with GBP-1. Altogether our findings indicated that GBP-1 may be a novel biomarker and an active component of a Th-1-like angiostatic immune reaction in CRC. This reaction may affect patient's response to antiangiogenic therapy and the identification of such tumors may provide a novel criterion for patient selection. Moreover, the induction of a Th-1-like angiostatic immune reaction may be a promising approach for the clinical treatment of CRC.

The SLAM and SAP gene families control innate and adaptive immune responses

The nine SLAM-family genes, SLAMF1-9, a subfamily of the immunoglobulin superfamily, encode differentially expressed cell-surface receptors of hematopoietic cells. Engagement with their ligands, which are predominantly homotypic, leads to distinct signal transduction events, for instance those that occur in the T or NK cell immune synapse. Upon phosphorylation of one or more copies of a unique tyrosine-based signaling motif in their cytoplasmic tails, six of the SLAM receptors recruit the highly specific single SH2-domain adapters SLAM-associated protein (SAP), EAT-2A, and/or EAT-2B. These adapters in turn bind to the tyrosine kinase Fyn and/or other protein tyrosine kinases connecting the receptors to signal transduction networks. Individuals deficient in the SAP gene, SH2D1A, develop an immunodeficiency syndrome: X-linked lympho-proliferative disease. In addition to operating in the immune synapse, SLAM receptors initiate or partake in multiple effector functions of hematopoietic cells, for example, neutrophil and macrophage killing and platelet aggregation. Here we discuss the current understanding of the structure and function of these recently discovered receptors and adapter molecules in the regulation of adaptive and innate immune responses.