Blimp-1/PRDM1 regulates the transcription of human CS1 (SLAMF7) gene in NK and B cells

The involvement of interferon regulatory factor 8 in regulating the proliferation of haemocytes in oyster Crassostrea gigas

Interferon regulatory factor 8 (IRF8) is an important transcriptional regulatory factor involving in multiple biological process, such as the antiviral immune response, immune cell proliferation and differentiation. In the present study, the involvement of a previously identified IRF8 homologue (CgIRF8) in regulating haemocyte proliferation of oyster were further investigated. CgIRF8 mRNA transcripts were detectable in all the stages of C. gigas larvae with the highest level in D-veliger (1.76-fold of that in zygote, p < 0.05). Its mRNA transcripts were also detected in all the three haemocyte subpopulations of adult oysters with the highest expression in granulocytes (2.79-fold of that in agranulocytes, p < 0.01). After LPS stimulation, the mRNA transcripts of CgIRF8 in haemocytes significantly increased at 12 h and 48 h, which were 2.04-fold and 1.65-fold (p < 0.05) of that in control group, respectively. Meanwhile, the abundance of CgIRF8 protein in the haemocytes increased significantly at 12 h after LPS stimulation (1.71-fold of that in seawater, p < 0.05). The immunofluorescence assay and Western blot showed that LPS stimulation induced an obvious nucleus translocation of CgIRF8 protein in haemocytes. After the expression of CgIRF8 was inhibited by the injection of CgIRF8 siRNA, the percentage of EdU positive haemocytes, the proportion of granulocytes, and the mRNA expression levels of CgGATA and CgSCL all declined significantly at 12 h after LPS stimulation, which was 0.64-fold (p < 0.05), 0.7-fold (p < 0.05), 0.31-fold and 0.54-fold (p < 0.001) of that in the NC group, respectively. While the expression level of cell proliferation-related protein CgCDK2, CgCDC6, CgCDC45 and CgPCNA were significantly increased (1.99-fold, and 2.41-fold, 3.76-fold and 4.79-fold compared to that in the NC group respectively, p < 0.001). Dual luciferase reporter assay demonstrated that CgIRF8 was able to activate the CgGATA promoter in HEK293T cells after transfection of CgGATA and CgIRF8. These results collectively indicated that CgIRF8 promoted haemocyte proliferation by regulating the expression of CgGATA and other related genes in the immune response of oyster.

Mutations in the DNA polymerase binding pathway affect the immune microenvironment of patients with small-cell lung cancer and enhance the efficacy of platinum-based chemotherapy

Background

Small-cell lung cancer (SCLC) is characterized by its high malignancy and is associated with a poor prognosis. In the early stages of the disease, platinum-based chemotherapy is the recommended first-line treatment and has demonstrated efficacy. However, SCLC is prone to recurrence and is generally resistant to chemotherapy in its later stages.

Methods

Here, we collected samples from SCLC patients who received platinum-based chemotherapy, performed genomic and transcriptomic analyses, and validated our results with publicly available data.

Results

SCLC patients with DNA polymerase binding pathway mutations had an improved prognosis after platinum chemotherapy compared with patients without such mutations. Patients in the mutant (MT) group had higher infiltration of T cells, B cells, and M1 macrophages compared with patients without DNA polymerase binding pathway mutations.

Conclusions

DNA polymerase binding pathway mutations can be used as prognostic markers for platinum-based chemotherapy in SCLC.

SLAMF7 as a Promising Immunotherapeutic Target in Multiple Myeloma Treatments

Multiple myeloma (MM) is a common hematological malignancy that has fostered several new therapeutic approaches to combat newly diagnosed or relapsed MM. While the field has advanced over the past 2 decades, the majority of patients will develop resistance to these treatments, causing the need for new therapeutic targets. SLAMF7 is an attractive therapeutic target in multiple myeloma, and a monoclonal antibody that targets SLAMF7 has shown consistent beneficial outcomes in clinical trials to date. In this review, we will focus on the structure and regulation of SLAMF7 and its mechanism of action. The most recent clinical trials will be reviewed to further understand the clinical implications and improve the prognosis of MM. Furthermore, the efficacy of anti-SLAMF7 monoclonal antibodies combined with standard therapies and possible resistance mechanisms will be discussed. This review aimed to provide a detailed summary of the role of SLAMF7 in the pathogenesis of patients with MM and the rationale for further investigation into SLAMF7-mediated molecular pathways associated with MM development.

CgBlimp-1 inhibits granulocytes proliferation and interleukin production in the immune response of oyster Crassostrea gigas

B lymphocyte-inducible maturation protein 1 (Blimp-1) is a SET domain and zinc fingers containing transcriptional repressor, which is necessary for regulating the development of many immune cell lineages and keeping immune homeostasis. In the present study, a Blimp-1 homologue (designated as CgBlimp-1) was identified from oyster Crassostrea gigas, which contained a conserved SET domain and five ZnF_C2H2 domains and shared high homology with Blimp-1 from other species. The mRNA transcripts of CgBlimp-1 were highly expressed in gill and hepatopancreas. CgBlimp-1 protein was detected to be specifically expressed in granulocytes. After V. splendidus stimulation, the mRNA expression level of CgBlimp-1 in haemocytes up-regulated significantly at 24, 48, and 96 h, which was 4.39-fold (p < 0.05), 7.68-fold (p < 0.01) and 2.65-fold (p < 0.05) of that in control group, respectively. When the expression of CgBlimp-1 was knocked-down in vivo by RNAi, the mRNA expressions of downstream transcription factor CgMyc-A (1.63-fold of that in control group, p < 0.05) and cell cycle related gene CgCDK2 (1.70-fold, p < 0.05) increased significantly at 24 h after V. splendidus stimulation. Concomitantly, the ratio of EdU⁺ haemocytes increased notably (p < 0.01) while the proportion of haemocytes in G0/G1 phase decreased dramatically (p < 0.001), compared to that in control group. More specifically, the proportion of granulocytes in total haemocytes increased apparently (p < 0.05) in CgBlimp-1-RNAi oysters, together with up-regulation (p < 0.05) of the ratio of EdU⁺ granulocytes and down-regulation (p < 0.001) of the proportion of granulocytes in G0/G1 phase. Furthermore, the mRNA expression levels of CgIL17-1, CgIL17-2 and CgIL17-4 in haemocytes increased significantly in CgBlimp-1-RNAi oysters, which was 1.71-fold (p < 0.05), 144.70-fold (p < 0.01) and 1.93-fold (p < 0.05) of that in control group, respectively. Aforementioned results suggested that CgBlimp-1 could reduce the proliferation of granulocytes by arresting cell cycle in G1/G0 phase and avoid over-expression of interleukin to maintain homeostasis in the immune response of oyster.

Fundamentals to therapeutics: Epigenetic modulation of CD8+ T Cell exhaustion in the tumor microenvironment

In the setting of chronic antigen exposure in the tumor microenvironment (TME), cytotoxic CD8+ T cells (CTLs) lose their immune surveillance capabilities and ability to clear tumor cells as a result of their differentiation into terminally exhausted CD8+ T cells. Immune checkpoint blockade (ICB) therapies reinvigorate exhausted CD8+ T cells by targeting specific inhibitory receptors, thus promoting their cytolytic activity towards tumor cells. Despite exciting results with ICB therapies, many patients with solid tumors still fail to respond to such therapies and patients who initially respond can develop resistance. Recently, through new sequencing technologies such as the assay for transposase-accessible chromatin with sequencing (ATAC-seq), epigenetics has been appreciated as a contributing factor that enforces T cell differentiation toward exhaustion in the TME. Importantly, specific epigenetic alterations and epigenetic factors have been found to control CD8+ T cell exhaustion phenotypes. In this review, we will explain the background of T cell differentiation and various exhaustion states and discuss how epigenetics play an important role in these processes. Then we will outline specific epigenetic changes and certain epigenetic and transcription factors that are known to contribute to CD8+ T cell exhaustion. We will also discuss the most recent methodologies that are used to study and discover such epigenetic modulations. Finally, we will explain how epigenetic reprogramming is a promising approach that might facilitate the development of novel exhausted T cell-targeting immunotherapies.

SLAMF7 engagement superactivates macrophages in acute and chronic inflammation

Macrophages regulate protective immune responses to infectious microbes, but aberrant macrophage activation frequently drives pathological inflammation. To identify regulators of vigorous macrophage activation, we analyzed RNA-seq data from synovial macrophages and identified SLAMF7 as a receptor associated with a superactivated macrophage state in rheumatoid arthritis. We implicated IFN-γ as a key regulator of SLAMF7 expression and engaging SLAMF7 drove a strong wave of inflammatory cytokine expression. Induction of TNF-α after SLAMF7 engagement amplified inflammation through an autocrine signaling loop. We observed SLAMF7-induced gene programs not only in macrophages from rheumatoid arthritis patients but also in gut macrophages from patients with active Crohn's disease and in lung macrophages from patients with severe COVID-19. This suggests a central role for SLAMF7 in macrophage superactivation with broad implications in human disease pathology.

On the road to eliminating long-lived plasma cells-"are we there yet?"

Central to protective humoral immunity is the activation of B cells and their terminal differentiation into antibody-secreting plasma cells. Long-lived plasma cells (LLPC) may survive for years to decades. Such long-lived plasma cells are also responsible for producing pathogenic antibodies that cause a variety of challenges such as autoimmunity, allograft rejection, and drug neutralization. Up to now, various therapeutic strategies aimed at durably eliminating pathogenic antibodies have failed, in large part due to their inability to efficiently target LLPCs. Several antibody-based therapies have recently gained regulatory approval or are in clinical phases of development for the treatment of multiple myeloma, a malignancy of plasma cells. We discuss the exciting potential of using these emerging cancer immunotherapies to solve the antibody problem.

Mechanisms of Action of the New Antibodies in Use in Multiple Myeloma

Monoclonal antibodies (mAbs) directed against antigen-specific of multiple myeloma (MM) cells have Fc-dependent immune effector mechanisms, such as complement-dependent cytotoxicity (CDC), antibody-dependent cellular cytotoxicity (ADCC), and antibody-dependent cellular phagocytosis (ADCP), but the choice of the antigen is crucial for the development of effective immuno-therapy in MM. Recently new immunotherapeutic options in MM patients have been developed against different myeloma-related antigens as drug conjugate-antibody, bispecific T-cell engagers (BiTEs) and chimeric antigen receptor (CAR)-T cells. In this review, we will highlight the mechanism of action of immuno-therapy currently available in clinical practice to target CD38, SLAMF7, and BCMA, focusing on the biological role of the targets and on mechanisms of actions of the different immunotherapeutic approaches underlying their advantages and disadvantages with critical review of the literature data.

SLAMF7 Signaling Reprograms T Cells toward Exhaustion in the Tumor Microenvironment

T cell exhaustion represents one of the most pervasive strategies tumors employ to circumvent the immune system. Although repetitive, cognate TCR signaling is recognized as the primary driving force behind this phenomenon, and it remains unknown what other forces drive T cell exhaustion in the tumor microenvironment (TME). In this study, we show that activation of the self-ligand SLAMF7 immune receptor on T cells induced STAT1 and STAT3 phosphorylation, expression of multiple inhibitory receptors, and transcription factors associated with T cell exhaustion. Analysis of The Cancer Genome Atlas revealed that SLAMF7 transcript levels were strongly correlated with various inhibitory receptors and that high SLAMF7 expression was indicative of poor survival in clear cell renal cell carcinoma (ccRCC). Targeted reanalysis of a CyTOF dataset, which profiled the TME in 73 ccRCC patients, revealed cell-type-specific SLAMF7 expression patterns, strong correlations between exhausted T cells and SLAMF7⁺ tumor-associated macrophages (TAMs), and a unique subset of SLAMF7^highCD38^high TAMs. These SLAMF7^highCD38^high TAMs showed the strongest correlations with exhausted T cells and were an independent prognostic factor in ccRCC. Confirmatory ex vivo coculture studies validated that SLAMF7-SLAMF7 interactions between murine TAMs and CD8⁺ T cells induce expression of multiple inhibitory receptors. Finally, mice lacking SLAMF7 show restricted growth of B16-F10 tumors, and CD8⁺ T cells from these mice express less PD-1 and TOX and exhibited an impaired ability to progress through the exhaustion developmental trajectory to terminal exhaustion. These findings suggest that SLAMF7 might play an important role in modulating T cell function in the TME.

Multi-Omics Resolves a Sharp Disease-State Shift between Mild and Moderate COVID-19

We present an integrated analysis of the clinical measurements, immune cells, and plasma multi-omics of 139 COVID-19 patients representing all levels of disease severity, from serial blood draws collected during the first week of infection following diagnosis. We identify a major shift between mild and moderate disease, at which point elevated inflammatory signaling is accompanied by the loss of specific classes of metabolites and metabolic processes. Within this stressed plasma environment at moderate disease, multiple unusual immune cell phenotypes emerge and amplify with increasing disease severity. We condensed over 120,000 immune features into a single axis to capture how different immune cell classes coordinate in response to SARS-CoV-2. This immune-response axis independently aligns with the major plasma composition changes, with clinical metrics of blood clotting, and with the sharp transition between mild and moderate disease. This study suggests that moderate disease may provide the most effective setting for therapeutic intervention.

The immune response after noise damage in the cochlea is characterized by a heterogeneous mix of adaptive and innate immune cells

Cells of the immune system are present in the adult cochlea and respond to damage caused by noise exposure. However, the types of immune cells involved and their locations within the cochlea are unclear. We used flow cytometry and immunostaining to reveal the heterogeneity of the immune cells in the cochlea and validated the presence of immune cell gene expression by analyzing existing single-cell RNA-sequencing (scRNAseq) data. We demonstrate that cell types of both the innate and adaptive immune system are present in the cochlea. In response to noise damage, immune cells increase in number. B, T, NK, and myeloid cells (macrophages and neutrophils) are the predominant immune cells present. Interestingly, immune cells appear to respond to noise damage by infiltrating the organ of Corti. Our studies highlight the need to further understand the role of these immune cells within the cochlea after noise exposure.

Roles of NK Cell Receptors 2B4 (CD244), CS1 (CD319), and LLT1 (CLEC2D) in Cancer

Natural killer (NK) cells play a pivotal role in the immune system, especially in the recognition and clearance of cancer cells and infected cells. Their effector function is controlled by a delicate balance between the activating and inhibitory signals. We have identified 2B4 (CD244, SLAMF4) and CS1 (CD319, SLAMF7) as NK cell receptors regulating NK cell cytotoxicity. Lectin-like transcript 1 (LLT1), a member of the C-type lectin-like domain family 2 (CLEC2D), induced IFN-γ production but did not directly regulate cytolytic activity. Interestingly, LLT1 expressed on other cells acts as a ligand for an NK cell inhibitory receptor NKRP1A (CD161) and inhibits NK cytolytic function. Extensive research has been done on novel therapies that target these receptors to increase the effector function of NK cells. The 2B4 receptor is involved in the rejection of melanoma cells in mice. Empliciti, an FDA-approved monoclonal antibody, explicitly targets the CS1 receptor and enhances the NK cell cytotoxicity against multiple myeloma cells. Our studies revealed that LLT1 is expressed on prostate cancer and triple-negative breast cancer cells and allows them to evade NK-cell-mediated killing. In this review, we describe NK cell receptors 2B4, CS1, and LLT1 and their potential in targeting cancer cells for NK-cell-mediated immunotherapy. New cancer immunotherapies like chimeric antigen receptor T (CAR-T) and NK (CAR-NK) cells are showing great promise in the treatment of cancer, and CAR cells specific to these receptors would be an attractive therapeutic option.

Association of circulating SLAMF7+Tfh1 cells with IgG4 levels in patients with IgG4-related disease

BACKGROUND

Follicular helper CD4+ T (Tfh) cells have a critical role in IgG4 production by B cells in IgG4-related disease (IgG4-RD). Recent studies including ours showed that SLAMF7+CD4+ T cells are an important pathological driver of IgG4-RD. In this study, we have sought to elucidate a relationship between helper CD4+ T (Th), particularly Tfh, cells and SLAMF7+ CD4+ T cells in IgG4-RD.

RESULTS

The patients with IgG4-RD enrolled in this study were aged 66 ± 12 years and their titers of serum IgG4 were 372 ± 336 mg/dl. Th1 cells, activated circulating Tfh1 (cTfh1), and activated cTfh2 cells increased in IgG4-RD. SLAMF7 was mainly expressed on Th1 and cTfh1, but not cTfh2, cells in the patients. SLAMF7+ cTfh1 cells were PD-1/CD28 double-positive, whereas SLAMF7+ Th1 cells were CD28 negative. Positive correlations were noted between serum IgG4 levels and the number of activated cTfh2 cells and SLAMF7+ cTfh1 cells, but not SLAMF7+ Th1 cells. Intriguingly, among cTfh1 cells, activated SLAMF7+ cTfh1 cells were high producers of IL-10 along with IL-21. Blimp-1, but not Bcl-6, mRNA was expressed at high levels in activated SLAMF7+ cTfh1 cells. In addition to CD4+ T cells, the frequency of SLAMF7+ fraction was higher in memory B cells than naïve B cells in patients with IgG4RD. Finally, upon stimulation via B-cell receptor and CD40, Tfh1-associated cytokines, IL-21 and IFN-γ, most significantly induced SLAMF7 expression in memory B cells.

CONCLUSIONS

Together, these results suggest that circulating SLAMF7+ Tfh1 cells, along with Tfh2 cells, play a pathologic role in IgG4 production in IgG4-RD.

BmBlimp-1 gene encoding a C2H2 zinc finger protein is required for wing development in the silkworm Bombyx mori

Cys2-His2 zinc finger (C2H2-ZF) proteins represent the most common class of transcription factors. These factors have great potential for the management of developmental progression by regulating the specific spatiotemporal expression of genes. In this study, we cloned one C2H2-ZF protein gene of Bombyx mori, BGIBMGA000319, that is orthologous to B-lymphocyte-induced maturation protein-1 (Blimp-1); we thus named it as Bombyx mori Blimp-1 (BmBlimp-1). In the silkworm, the BmBlimp-1 gene is specifically upregulated during day 2 of the pupal to adult stage and is highly expressed in wing discs on day 3 of the pupa. Knockdown of its expression level in the pupal stage results in a crumpled-winged silkworm moth. Using the predicted DNA-binding sequences of BmBlimp-1 to search the silkworm genome to screen target genes of BmBlimp-1, 7049 genes were identified to have at least one binding site of BmBlimp-1 on their 1 kb upstream and downstream genome regions. Comparisons of those genes with a reported pupal wing disc transcriptome data resulted in 4065 overlapping genes being retrieved. GO enrichment analysis of the overlapping genes showed that most of the genes were enriched in the binding term. Combining functional annotation and real-time quantitative PCR, 15 genes were identified as the candidate target genes of BmBlimp-1, including several wing cuticular protein genes, chitin synthase A, and wing disc development genes, such as Wnt1, cubitus interruptus (ci) and engrailed (en). Moreover, the amino acid sequence of the zinc finger motif of Blimp-1 gene was highly conserved among the 15 insect species. We propose that BmBlimp-1 is an important regulatory factor in silkworm wing development.

Soluble SLAMF7 promotes the growth of myeloma cells via homophilic interaction with surface SLAMF7

SLAMF7 is expressed mainly on multiple myeloma (MM) cells and considered an ideal target for immunotherapeutic approaches. Indeed, elotuzumab, an anti-SLAMF7 antibody, is used for the treatment of MM in combination with immunomodulatory drugs. SLAMF7 is cleaved via unknown mechanisms and detected as a soluble form (sSLAMF7) exclusively in the serum of MM patients; however, little is known about the role of sSLAMF7 in MM biology. In this study, we found that sSLAMF7 enhanced the growth of MM cells via homophilic interaction with surface SLAMF7 and subsequent activation of the SHP-2 and ERK signaling pathways. Elotuzumab suppressed sSLAMF7-induced MM cell growth both in vitro and in vivo. Promoter analyses identified IKZF1 (Ikaros) as a pivotal transcriptional activator of the SLAMF7 gene. Pharmacological targeting of Ikaros by lenalidomide and its analog pomalidomide downregulated SLAMF7 expression and ameliorated the response of MM cells to sSLAMF7. Elotuzumab blocked the growth-promoting function of sSLAMF7 when combined with lenalidomide in a murine xenograft model. Neutralization of sSLAMF7 is a novel antimyeloma mechanism of elotuzumab, which is enhanced by immunomodulatory drugs via downregulation of surface SLAMF7 expression on MM cells. These findings may provide important information for the optimal use of elotuzumab in MM treatment.

The LL-100 panel: 100 cell lines for blood cancer studies

For many years, immortalized cell lines have been used as model systems for cancer research. Cell line panels were established for basic research and drug development, but did not cover the full spectrum of leukemia and lymphoma. Therefore, we now developed a novel panel (LL-100), 100 cell lines covering 22 entities of human leukemia and lymphoma including T-cell, B-cell and myeloid malignancies. Importantly, all cell lines are unequivocally authenticated and assigned to the correct tissue. Cell line samples were proven to be free of mycoplasma and non-inherent virus contamination. Whole exome sequencing and RNA-sequencing of the 100 cell lines were conducted with a uniform methodology to complement existing data on these publicly available cell lines. We show that such comprehensive sequencing data can be used to find lymphoma-subtype-characteristic copy number aberrations, mRNA isoforms, transcription factor activities and expression patterns of NKL homeobox genes. These exemplary studies confirm that the novel LL-100 panel will be useful for understanding the function of oncogenes and tumor suppressor genes and to develop targeted therapies.

Elotuzumab for the Treatment of Relapsed or Refractory Multiple Myeloma, with Special Reference to its Modes of Action and SLAMF7 Signaling

Elotuzumab, targeting signaling lymphocytic activation molecule family 7 (SLAMF7), has been approved in combination with lenalidomide and dexamethasone (ELd) for relapsed/refractory multiple myeloma (MM) based on the findings of the phase III randomized trial ELOQUENT-2 (NCT01239797). Four-year follow-up analyses of ELOQUENT-2 have demonstrated that progression-free survival was 21% in ELd versus 14% in Ld. Elotuzumab binds a unique epitope on the membrane IgC2 domain of SLAMF7, exhibiting a dual mechanism of action: natural killer (NK) cell-mediated antibody-dependent cellular cytotoxicity (ADCC) and enhancement of NK cell activity. The ADCC is mediated through engagement between Fc portion of elotuzumab and FcgRIIIa/CD16 on NK cells. Enhanced NK cell cytotoxicity results from phosphorylation of the immunoreceptor tyrosine-based switch motif (ITSM) that is induced via elotuzumab binding and recruits the SLAM-associated adaptor protein EAT-2. The coupling of EAT-2 to the phospholipase Cg enzymes SH2 domain leads to enhanced Ca²⁺ influx and MAPK/Erk pathway activation, resulting in granule polarization and enhanced exocytosis in NK cells. Elotuzumab does not stimulate the proliferation of MM cells due to a lack of EAT-2. The inhibitory effects of elotuzumab on MM cell growth are not induced by the lack of CD45, even though SHP-2, SHP-1, SHIP-1, and Csk may be recruited to phosphorylated ITSM of SLAMF7. ELd improves PFS in patients with high-risk cytogenetics, i.e. t(4;14), del(17p), and 1q21 gain/amplification. Since the immune state is paralytic in advanced MM, the efficacy of ELd with minimal toxicity may bring forward for consideration of its use in the early stages of the disease.

PRDI-BF1 and PRDI-BF1P isoform expressions correlate with disease status in multiple myeloma patients

Human positive regulatory domain I binding factor 1 (PRDI-BF1 or BLIMP-1) is a transcription factor that acts as a master regulator and has crucial roles in the control of differentiation and in maintaining survival of plasma cells (PC). The PRDM1 gene, which codifies for PRDI-BF1, contains an alternative promoter capable of generating a PRDI-BF1 deleted protein (called PRDI-BF1β), which lacks 101 amino acids comprising most of the regulatory domain. PRDI-BF1β has been detected in relevant quantities especially in multiple myeloma cell lines (U266 and NCI- H929). The first aim of the study was to compare, using real time polymerase chain reaction (RT-PCR), the levels of PRDI-BF1 and PRDI-BF1β in myeloma patients and in normal human bone marrow. The second step was the examination of the expression of PRDI-BF1 and PRDI-BF1β isoform depending on disease status and treatment response. We demonstrate the correlation of PRDI-BF1 and the shorter PRDI-BF1β isoform protein levels with the clinical evolution and the management of myeloma patients.