Lymphocytic Activation Molecule Family Member Research Articles

Evidence for the loss and recovery of SLAMF9 during human evolution: implications on Dollo's law.

Signaling lymphocyte activation molecule family member 9 (SLAMF9) is a cell surface protein of the CD2/SLAM family of leukocyte surface receptors. It is conserved throughout mammals and has roles in the initiation of inflammatory responses and regulation of plasmacytoid dendritic cell function. Through comparison of reference sequences encoding SLAMF9 in human, mouse, and primate sequences, we have determined that the SLAMF9 gene underwent successive mutation events, resulting in the loss of the protein and subsequent recovery of a less stable version. The mutations included a single base pair deletion in the second exon and a change in the splice acceptor site of that same exon. These changes would have had the effect of creating and later repairing a frameshift in the coding sequence. These events took place since the divergence of the human lineage from the chimpanzee-human last common ancestor and represent the first known case of the functional loss and recovery of a gene within the human lineage.

The relationship of indoxyl sulfate and p-cresyl sulfate with target cardiovascular proteins in hemodialysis patients

Protein-bound uremic toxins (Indoxyl sulfate [IS] and p-cresyl sulfate [PCS]) are both associated with cardiovascular (CV) and all-cause mortality in subjects with chronic kidney disease (CKD). Possible mechanisms have not been elucidated. In hemodialysis patients, we investigated the relationship between the free form of IS and PCS and 181 CV-related proteins. First, IS or PCS concentrations were checked, and high levels were associated with an increased risk of acute coronary syndrome (ACS) in 333 stable HD patients. CV proteins were further quantified by a proximity extension assay. We examined associations between the free form protein-bound uremic toxins and the quantified proteins with correction for multiple testing in the discovery process. In the second step, the independent association was evaluated by multivariable-adjusted models. We rank the CV proteins related to protein-bound uremic toxins by bootstrapped confidence intervals and ascending p-value. Six proteins (signaling lymphocytic activation molecule family member 5, complement component C1q receptor, C–C motif chemokine 15 [CCL15], bleomycin hydrolase, perlecan, and cluster of differentiation 166 antigen) were negatively associated with IS. Fibroblast growth factor 23 [FGF23] was the only CV protein positively associated with IS. Three proteins (complement component C1q receptor, CCL15, and interleukin-1 receptor-like 2) were negatively associated with PCS. Similar findings were obtained after adjusting for classical CV risk factors. However, only higher levels of FGF23 was related to increased risk of ACS. In conclusion, IS and PCS were associated with several CV-related proteins involved in endothelial barrier function, complement system, cell adhesion, phosphate homeostasis, and inflammation. Multiplex proteomics seems to be a promising way to discover novel pathophysiology of the uremic toxin.

Transcriptome analysis of Mycoplasma bovis stimulated bovine peripheral blood mononuclear cells

Mycoplasma bovis is a pathogenic bacterium in bovines that causes huge global economic losses. Numerous factors play important roles in M. bovis pathogenesis; however, the host immune response involved in M. bovis infection has not been fully elucidated. We aimed to determine the characteristics of the host immune response to Mycoplasma infection. We evaluated the responsiveness of bovine peripheral blood mononuclear cells (PBMCs) stimulated with M. bovis via microarray analysis. The transcriptional abundance of innate immune-related genes IL-36A, IL-27, IFN-γ, and IL-17 in PBMCs increased after M. bovis exposure. Upon M. bovis infection, there was increased expression of the lymphocyte activated genes basic leucine zipper transcription factor (BATF) and signaling lymphocytic activation molecule family members 1 and 7 (SLAMF 1 and SLAMF 7) in PBMCs compared with that in unstimulated cells. The study revealed that the transcriptional abundance of innate immunity genes in PBMCs increased during M. bovis infection. This induced the activation of PBMCs, giving rise to an immune response, which is followed by the development of the inflammatory response. The results from this study could be used as the basis for the development of novel vaccine candidates against M. bovis.

SLAMF1 Promotes Methotrexate Resistance via Activating Autophagy in Choriocarcinoma Cells.

ObjectiveThe acquisition of chemoresistance to methotrexate (MTX) still remains one of the major challenges for choriocarcinoma treatment. Herein, we aimed to evaluate the potential role of Signaling Lymphocytic Activation Molecule Family Member 1 (SLAMF1) as a possible regulator of chemoresistance to MTX in choriocarcinoma.Material and MethodsMTX-resistant JEG3 and JAR sublines (JEG3/MTX, JAR/MTX) were used to study SLAMF1 function. CCK8 assay and soft agar assay were conducted to measure the cell viability and clonogenesis of choriocarcinoma cells, respectively; MDC incorporation assay was conducted for the quantification of intracellular autophagy; BrdU labeling was used to assess the proliferative potential of choriocarcinoma cells; SLAMF1 protein expression was analyzed by Western blotting.ResultsUpregulation of SLAMF1 expression was observed in MTX-resistant JEG3/MTX and JAR/MTX sublines compared to their parental JEG3 and JAR cell lines, respectively. Knockdown of SLAMF1 markedly attenuated cell viability and soft agar clonogenesis after incubation with MTX in JEG3/MTX and JAR/MTX cells. In contrast, constitutive expression of SLAMF1 rescued cell survival soft agar clonogenesis in JEG3 and JAR cells treated with MTX. Moreover, autophagy is apparently activated in MTX-resistant JEG3/MTX and JAR/MTX sublines compared to their parental cell lines. Autophagy inhibitor 3-methyladenine and bafilomycin A1 enhanced MTX-induced cytotoxicity in MTX-resistant JEG3 and JAR sublines. Further, SLAMF1 might activate autophagy-related mechanism to promote resistance to MTX in choriocarcinoma cells. Depletion of SLAMF1 suppressed autophagy and induced apoptosis in MTX-treated JEG3/MTX and JAR/MTX cells.ConclusionSLAMF1 might promote MTX resistance via activating protective autophagy in choriocarcinoma cell lines. Targeting SLAMF1 might be a useful therapeutic strategy to sensitize choriocarcinoma cells to MTX-based regimens.

SLAMF1 signaling induces Mycobacterium tuberculosis uptake leading to endolysosomal maturation in human macrophages.

Tuberculosis dates back to ancient times but it is not a problem of the past. Each year, millions of people die from tuberculosis. After inhalation of infectious droplet nuclei, Mycobacterium tuberculosis reaches the lungs where it can manipulate the immune system and survive within host macrophages, establishing a persistent infection. The signaling lymphocytic activation molecule family member 1 (SLAMF1) is a self-ligand receptor that can internalize gram-negative bacteria and regulate macrophages' phagosomal functions. In tuberculosis, SLAMF1 promotes Th1-protective responses. In this work, we studied the role of SLAMF1 on macrophages' functions during M. tuberculosis infection. Our results showed that both M. tuberculosis and IFN-γ stimulation induce SLAMF1 expression in macrophages from healthy donor and Tohoku Hospital Pediatrcs-1 cells. Costimulation through SLAMF1 with an agonistic antibody resulted in an enhanced internalization of M. tuberculosis by macrophages. Interestingly, we found that SLAMF1 interacts with M. tuberculosis and colocalizes with the bacteria and with early and late endosomes/lysosomes markers (EEA1 and LAMP2), suggesting that SLAMF1 recognize M. tuberculosis and participate in the endolysosomal maturation process. Notably, increased levels of SLAMF1 were detected in CD14 cells from pleural effusions of tuberculosis patients, indicating that SLAMF1 might have an active function at the site of infection. Taken together, our results provide evidence that SLAMF1 improves the uptake of M. tuberculosis by human monocyte-derived macrophages.

P1286THE RELATIONSHIP BETWEEN PROTEIN-BOUND UREMIC TOXINS AND TARGET CARDIOVASCULAR PROTEINS IN HEMODIALYSIS PATIENTS

Abstract Background and Aims Uremic toxins are crucial non-traditional risk factors for cardiovascular disease in patients with chronic kidney disease (CKD). Indoxyl sulfate (IS) and p-cresyl sulfate (PCS) were associated with all-cause and cardiovascular mortality in CKD patients, but possible mechanisms have not been fully elucidated. Herein, we explored the association between protein-bound uremic toxins and 181 cardiovascular-specific proteins in patients receiving hemodialysis (HD). Method In the discovery phase, we investigated associations between circulating free form IS and PCS and cardiovascular-specific protein levels quantified by a proximity extension assay of 333 stable HD patients with correction for multiple testing. In the second phase, the independent association was assessed using multivariable-adjusted models. The associations of IS or PCS with cardiovascular-specific proteins levels on a continuous scale were also evaluated. Results Free form IS was negatively associated with six proteins (C-C motif chemokine 15, complement component C1q receptor, perlecan, bleomycin hydrolase, cluster of differentiation 166 antigen, and signaling lymphocytic activation molecule family member 5) and positively associated with one protein (fibroblast growth factor 23). Free form PCS was negatively associated with three proteins (C-C motif chemokine 15, complement component C1q receptor, and interleukin-1 receptor-like 2). Adjusting the multivariable models for classical cardiovascular risk factors at baseline yielded similar results. Conclusion Protein-bound uremic toxins (IS and PCS) were associated with several cardiovascular-specific proteins involved in cell adhesion, endothelial barrier function, inflammation, complement system, and phosphate homeostasis. Multiplex proteomics appears to be a promising way to explore novel aspects of uremic toxin pathophysiology.

A single-marker method of renal cDC2 isolation

Abstract Because of their ability to present antigens, respond to inflammatory signals, and produce critical acute-phase cytokines, renal dendritic cells are of particular interest to those studying various disease states of the kidney. Markers such as CD11c, MHC-II, CX3CR1, and CD11b have historically been used in the murine system to isolate renal dendritic cells from the various parenchymal cells among which they’re embedded. In this study, we have determined that signaling lymphocyte activation molecule family member 9 (SLAMF9) is sufficient to mark the population of CD11b+ MHCIIhi CX3CR1+ CD11c+ F4/80+ cells in the murine kidney under homeostatic conditions. Using SLAMF9, we have devised a single-marker method of renal cDC2 isolation via fluorescence-activated cell sorting (FACS). This method will allow isolation of mouse CD11b+ dendritic cells with minimal surface receptor interference.

SLAM family member 8 is expressed in and enhances the growth of anaplastic large cell lymphoma

Signaling lymphocytic activation molecule family member 8 (SLAMF8) / B-lymphocyte activator macrophage expressed/CD353 is a member of the CD2 family. SLAMF8 suppresses macrophage function but enhances the growth of neoplastic mast cells via SHP-2. In this study, we found that some anaplastic large cell lymphoma (ALCL) samples were immunohistochemically positive for SLAMF8. However, we found no significant differences between SLAMF8-positive and SLAMF8-negative ALCL samples with respect to age, gender, site, or prognosis. We also identified SLAMF8 expression in ALCL cell lines, Karpas299, and SU-DHL-1. SLAMF8 knockdown decreased the activation of SHP-2 and the growth of these cell lines, and increased the apoptosis of these cell lines. In addition, we observed the interaction between SLAMF8 and SHP-2 in these cell lines using the DuoLink in situ kit. Taken together, these results suggest that SLAMF8 may enhance the growth of ALCL via SHP-2 interaction.

Signalling lymphocyte activation molecule family member 9 is found on select subsets of antigen-presenting cells and promotes resistance to Salmonella infection.

SummarySignalling lymphocyte activation molecule family member 9 (SLAMF9) is an orphan receptor of the CD2/SLAM family of leucocyte surface proteins. Examination of SLAMF9 expression and function indicates that SLAMF9 promotes inflammation by specialized subsets of antigen‐presenting cells. Within healthy liver and circulating mouse peripheral blood mononuclear cells, SLAMF9 is expressed on CD11b+, Ly6C−, CD11clow, F4/80low, MHC‐II+, CX3CR1+ mononuclear phagocytes as well as plasmacytoid dendritic cells. In addition, SLAMF9 can be found on peritoneal B1 cells and small (F4/80low), but not large (F4/80high), peritoneal macrophages. Upon systemic challenge with Salmonella enterica Typhimurium, Slamf9−/− mice were impaired in their ability to clear the infection from the liver. In humans, SLAMF9 is up‐regulated upon differentiation of monocytes into macrophages, and lipopolysaccharide stimulation of PMA‐differentiated, SLAMF9 knockdown THP‐1 cells showed an essential role of SLAMF9 in production of granulocyte–macrophage colony‐stimulating factor, tumour necrosis factor‐α, and interleukin‐1β. Taken together, these data implicate SLAMF9 in the initiation of inflammation and clearance of bacterial infection.

CAR-T cells in multiple myeloma: current status

SummaryStarting with the approval of bortezomib, a proteasome-inhibiting drug, tremendous progress has been achieved in the treatment of multiple myeloma (MM) patients during the last 15 years. Due to a plethora of novel drugs such as second generation proteasome inhibitors, immunomodulating agents and monoclonal antibodies the 5‑year survival of MM patients has been extended from 33% at the turn of the millennium to approximately 60% in younger patients (<65–70 years) who were eligible for consolidation with high-dose chemotherapy and autologous stem cell transplantation. Unfortunately, virtually all patients suffer from relapse and ultimately succumb to the disease, indicating the need for additional treatment strategies. Currently there are two promising immunologic approaches. First, bispecific antibodies called BITE (bispecific T-cell enhancer), which act as fusion proteins with two single-chain variable fragments, target antigens on malignant cells and bind the CD3 receptor and thereby recruit T‑cells to the target cells. The second strategy is chimeric antigen receptor (CAR) engineered T‑cell therapy that attacks myeloma cells by recognizing specific targets such as CD138, BCMA (B-cell maturation antigen), light-chains, SLAM-F7 (signaling lymphocytic activation molecule family member 7) or the pan B‑cell antigen CD19.Several early phase clinical trials show encouraging results in patients who have relapsed after modern treatment including proteasome inhibitors, immunomodulating drugs and monoclonal antibodies. Here, we briefly summarize current clinical knowledge about CAR‑T cell treatment in multiple myeloma, including clinical data presented at the 61st American Society of Hematology annual meeting held in December 2019 in Orlando.

Mammary SLAMF3 Regulates Store-Operated Ca2+ Entry and Migration Through STIM1 in Breast Cancer Cells and Cell Lines

Abstract: Store Operated Calcium Entry (SOCE) is the main route for calcium entry in breast cells. After it’s activation by STromal Interaction Molecule (STIM) during endoplasmic reticulum store depletion, membrane channels ORAI are the main actors of this cell calcium entry. STIM, ORAI and SOCE alterations might contribute to Breast Cancer (BC) carcinogenesis. Recently, we reported the tumor suppressor role of Signaling Lymphocytic Activation Molecule Family member 3 (SLAMF3) on HepatoCellular Carcinoma (HCC) progression. SLAMF3 has been shown to regulate the activity of immune cells by modulating the calcium influx. In this report, we aimed at exploring the role of SLAMF3 in regulating SOCE and migration of BC cells. We quantified and compared the expression of SLAMF3 and STIM1 by quantitative RT-PCR in tumor and healthy resections of 14 patients followed at the University Hospital of Amiens. The expressions of SLAMF3 and STIM1 were also quantified and compared in non-invasive T47D and invasive MDA-MB-231 cell lines by quantitative RT-PCR, Western blot and flow cytometry. We determined the Ca2+ basal entry as well as SOCE by Mn2+ quenching and calcium imaging, respectively, in T47D and MDA-MB-231 cells overexpressing SLAMF3 ectopically. The cell proliferation and migration/invasion were investigated by MTT, wound healing assay and Boyden chambers tests, respectively. First, we report the expression of SLAMF3 in mammary epithelial cells. We highlight the complete loss of SLAMF3 expression in invasive BC cell lines compared to non-invasive cells. In addition, we show that the forced expression of SLAMF3 in invasive cells down-regulate specifically the STIM1 expression in invasive compared to non-invasive mammary cell lines. Interestingly, an inverse correlation is observed between the low expression of SLAMF3 and the high expression of STIM1 in primary human BC tissues. Our results indicate that SLAMF3 reduces SOCE and therefore restricts BC cell migration by decreasing STIM1 expression. Therefore, SLAMF3 might be used as a predictive marker of BC evolution and aggressiveness.

Antibody Based Three-Drug Regimens for Multiple Myeloma - a Systematic Review of Phase II and Phase III Clinical Trials

Antibody Based Three-Drug Regimens for Multiple Myeloma - a Systematic Review of Phase II and Phase III Clinical Trials

Efficacy of Elotuzumab Based Combinations in Patients with Multiple Myeloma - a Systematic Review

Introduction Multiple myeloma afflicted cells express signaling lymphocytic activation molecule family member 7 (SLAMF7). Elotuzumab; a monoclonal antibody (mAb), targets SLAMF7 and fights myeloma cells by stimulating phagocytic action of natural killer (NK) cells and via antibody‐dependent cell‐mediated cytotoxicity (ADCC) pathway. This study focuses on the clinical utility and tolerability of elotuzumab based combinations in patients (pts) with multiple myeloma (MM). Methods Literature search of PubMed, Embase, Clinicaltrials.gov, Cochrane and Web of Science was performed from inception to June 12, 2019 for elotuzumab based combinations in MM patients. Total of 06 phase II and phase III clinical trials were selected for systematic review out of 292 studies. Results Elotuzumab (E) based combinations were evaluated in 1075 patients (pts) out of 1115 enrolled pts. 119 were newly diagnosed (ND) and 956 were relapsed/refractory (RR) patients. Newly Diagnosed MM patients: Takezako et al. 2017; in phase II trial, showed overall response rate (ORR) of 88% (complete response [CR] 3% + stringent CR [sCR] 5% + partial response [PR] 43% + very good partial response [VGPR] 38%) with ELd (E-Lenalidomide-dexamethasone) arm vs 74% in Ld arm in 82 ND pts. Progression free survival (PFS) at 1 year (y) was 93% versus (vs) 91%. Grade (G) ≥3 adverse events (AEs) included neutropenia (18%) and leukopenia (15%). Relapsed/Refractory MM patients: E-Bortezomib(B)-d arm in a phase II trial by Jakubowiak et al. (2016) showed 1 y PFS of 39% vs 33% in Bd arm in 152 RR pts (Hazard ratio [HR]: 0.72; p = .09) with 28% decrease in progression or death with EBd vs Bd arm. Objective response rate (ORR) was 66% (4% CR+ 33% VGPR + 30% PR) vs 63%. OS (overall survival) at 1 y was 85% (EBd) and 74% (Bd) (HR: 0.6). G≥3 AEs were infections (21%), thrombocytopenia and peripheral neuropathy (9% each). Mateos et al. (2016) in phase II trial (n=40) evaluated E-T (thalidomide)-d with or without Cy (cyclophosphamide) in heavily pre-treated RR pts. Pts received Cy if they failed to achieve PR by the 5th cycle or because of progressive disease (PD). Responses were better with ETd vs ETdCy. ORR was 38% (95% CI: 23-54) in ETd vs 9% (95% CI: 0-41) in ETdCy. Entire study yielded median PFS (mPFS) of 3.9 months (mo) (95% CI: 2.79%-9.43%) with 1-y PFS of 30% and mOS of 16.3 mo (95% Cl: 8.87%-25.66%) with 1-y survival rate of 63%. G≥3 AEs were lymphopenia (50%), anemia (20%), leucopenia (20%) and respiratory tract infections (RTI) (8%). Dimopoulos et al. 2018 studied E + pomalidomide (P) + d (EPd) for RR pts with ≥2 prior therapies in phase II ELOQUENT-3 trial (n=117). EPd arm yielded mPFS of 10.2 mo vs 4.6 mo in Pd arm [HR: 0.54 (95% CI: 0.34-0.86; p=0.008)], i.e. 46% lower risk of progression or death in EPd vs Pd arm. ORR was 53% (CR 5% + sCR 3% + PR 33% + VGPR 12%) in EPd vs 26% in Pd arm (odds ratio [OR]: 3.25 (1.49-7.11). G≥3 AEs were anemia (10%), neutropenia and infections (13% each). Phase III ELOQUENT-2 trial randomized 646 RR pts. PFS at 4 y was 21% vs 14% (HR: 0.71, 95% CI: 0.59-0.86; p= .0004), favoring ELd with 29% reduction in myeloma progression or death. With VGPR of 30%, ORR was 79% vs 66 % (ELd vs Ld) with HR: 0.77; 95% CI: 0.62-0.95; p = 0.0176. OS at 4 y was 50% vs 43% (HR: 0.78; 95% CI: 0.63-0.96). G≥3 AEs included lymphocytopenia (79%), neutropenia (36%), anemia (20%) and thrombocytopenia (21%). (Dimopoulos et al, 2018). Newly Diagnosed & Relapsed/Refractory MM patients: Phase II trial (n=70) by Berenson et al. (2017) studied G≥3 infusion reactions (IRs) using ELd in ND (n=37) and RR (n=33) pts. ORR was 78% (95% CI: 62%‐90%) for ND and 61% (95% CI: 42%‐77%) for RR pts. Other response rates were CR 6%, VGPR 27% and PR 37% in all patients. G3 AEs included anemia in 10% pts (no G3 IRs were seen). Conclusion: Elotuzumab based combinations showing promising outcomes in terms of ORR, PFS and OS for ND and RR MM patients with tolerable toxicity profile. More clinical studies with elotuzumab in unique and newer combinations need to be tested in prospective trials. Disclosures Anwer: In-Cyte: Speakers Bureau; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees.

Recurrent inflammatory disease caused by a heterozygous mutation in CD48

Recurrent inflammatory disease caused by a heterozygous mutation in CD48

Upregulation of SLAMF3 on human T cells is induced by palmitic acid through the STAT5-PI3K/Akt pathway and features the chronic inflammatory profiles of type 2 diabetes

Metabolic stress-induced low-grade chronic inflammation plays an important role in the development of insulin-resistance and type 2 diabetes (T2D). Emerging evidence highlights the importance of directly elucidating T-cell activation under the obesity-induced metabolic stress condition, as T cells primed under such conditions were found to acquire a unique phenotype and function. Herein, we found a significant upregulation of signaling lymphocytic activation molecule family member 3 (SLAMF3) expression on T cells from T2D patients compared to those of healthy controls. Importantly, SLAMF3 upregulation was associated with an increased ability to produce proinflammatory cytokines. Significantly increased SLAMF3 expression was seen in T2D patient T cells that produce IFN-γ or IL-17 upon short (4-h) stimulation, compared to non-cytokine-producing T cells. In line with this finding, SLAMF3high T cells were significantly more sensitive than SLAMF3low T cells to TCR stimulation with anti-CD3/CD28 antibodies. Furthermore, treatment with palmitic acid (PA) led to significant upregulation of SLAMF3 on human T cells primed by anti-CD3/CD28 antibodies and on Jurkat cells, a human T-cell line. RNA sequencing revealed strong activation of the PI3K/Akt signaling pathway in T cells that were primed with PA. Further mechanistic studies showed that inhibition of PI3K/Akt signaling, or its upstream mediator STAT5 can prevent PA-induced SLAMF3 upregulation on T cells. These results indicate that SLAMF3 upregulation is associated with T-cell activation and cytokine production in T2D patients, and suggest that elevated saturated fatty acids in T2D patients may induce SLAMF3 upregulation on T cells via activation of the STAT5-PI3K/Akt signaling pathway.

Update on elotuzumab for the treatment of relapsed/refractory multiple myeloma: patients' selection and perspective.

Monoclonal antibodies (mAbs) targeting antigens expressed by plasma cells demonstrated major clinical activity in multiple myeloma patients and therefore became a new major class of drug for these patients. Elotuzumab is a humanized mAb targeting the cell surface signaling lymphocytic activation molecule family member 7, a glycoprotein highly expressed on plasma cells, that is the second mAb approved for the treatment of myeloma patients. The mechanism of action of elotuzumab includes natural killer cell (NK) mediated antibody-dependent cellular cytotoxicity and direct activation of NK-cells. Elotuzumab has been approved in combination with lenalidomide and dexamethasone (Elo-Rd) and pomalidomide and dexamethasone (Elo-Pd) for the treatment of relapsed myeloma patients. The present review will focus on elotuzumab, providing a summary of the mechanism of action, efficacy and safety and taking into consideration patients’ selection.

Signaling Lymphocytic Activation Molecule Family Member 1 Engagement Inhibits T Cell-B Cell Interaction and Diminishes Interleukin-6 Production and Plasmablast Differentiation in Systemic Lupus Erythematosus.

Signaling lymphocytic activation molecule family member 1 (SLAMF1) homophilic interactions promote immunoglobulin production and T cell-B cell cross-talk. SLAMF1 is overexpressed on T and B cells in patients with systemic lupus erythematosus (SLE). This study was undertaken to determine the role of SLAMF1 monoclonal antibody (mAb) in modulating T cell-B cell interaction and B cell activation. Anti-IgM-prestimulated naive or total B cells from either healthy donors or patients with SLE were cocultured with autologous T cells under CD3/CD28 stimulation, in the presence or absence of the SLAMF1 mAb. Naive B cells were stimulated with anti-IgM and CD40L in the presence of the SLAMF1 antibody. Cytokine production by CD4+ T cells and B cells was examined by flow cytometry and/or quantitative polymerase chain reaction. Plasmablast formation and T cell and B cell conjugates were assessed by flow cytometry. IgG and antinuclear antibody production was determined by enzyme-linked immunosorbent assay. SLAMF1 ligation in a human peripheral blood T cell-B cell culture system reduced the following in both healthy controls and patients with SLE: conjugate formation, interleukin-6 (IL-6) production by B cells, IL-21 and IL-17A production by T cells, and Ig and autoantibody production. Whereas the SLAMF1 mAb directly affected the function of isolated peripheral B cells by decreasing IL-6 and Ig production in vitro, it did not affect cytokine production by isolated T cells stimulated in vitro. The SLAMF1 antibody inhibits T cell-B cell interaction and suppresses B cell cytokine production and differentiation, thereby acting as a potential therapeutic tool in the treatment of patients with SLE.

Elotuzumab Promotes Self-Engagement of Signaling Lymphocytic Activation Molecule Family Member 7 (SLAMF7) Between Natural Killer (NK) and Multiple Myeloma (MM) Cells to Enhance Cytotoxicity

Elotuzumab Promotes Self-Engagement of Signaling Lymphocytic Activation Molecule Family Member 7 (SLAMF7) Between Natural Killer (NK) and Multiple Myeloma (MM) Cells to Enhance Cytotoxicity

SLAM family member 8 is involved in oncogenic KIT-mediated signalling in human mastocytosis.

The signalling lymphocytic activation molecule family member 8 (SLAMF8)/CD353 is a member of the CD2 family of proteins. Its ligand has not been identified. SLAMF8 is expressed by macrophages and suppresses cellular functions. No study has yet explored SLAMF8 expression or function in human mastocytosis, which features oncogenic KIT-mediated proliferation of human mast cells. SLAMF8 protein was expressed in human mastocytosis cells, immunohistochemically. SLAMF8 expression was also evident in the human mast cell lines, HMC1.2 (expressing oncogenic KIT) and LAD2 (expressing wild-type KIT) cells. SLAMF8 knock-down significantly reduced the KIT-mediated growth of HMC1.2 cells but not that of LAD2 cells. SLAMF8 knock-down HMC1.2 cells exhibited significant attenuation of SHP-2 activation and oncogenic KIT-mediated RAS-RAF-ERK signalling. An interaction between SLAMF8 and SHP-2 was confirmed in HMC1.2 cells and all pathological mastocytosis specimens examined (19 of 19 cases, 100%). Thus, SLAMF8 is involved in oncogenic KIT-mediated RAS-RAF-ERK signalling and the subsequent growth of human neoplastic mast cells mediated by SHP-2. SLAMF8 is a possible therapeutic target in human mastocytosis patients.

A CD8α- Subset of CD4+SLAMF7+ Cytotoxic T Cells Is Expanded in Patients With IgG4-Related Disease and Decreases Following Glucocorticoid Treatment.

An unconventional population of CD4+ signaling lymphocytic activation molecule family member 7-positive (SLAMF7+) cytotoxic effector memory T (TEM ) cells (CD4+ cytotoxic T lymphocytes [CTLs]) has been linked causally to IgG4-related disease (IgG4-RD). Glucocorticoids represent the first-line therapeutic approach in patients with IgG4-RD, but their mechanism of action in this specific condition remains unknown. We undertook this study to determine the impact of glucocorticoids on CD4+ CTLs in IgG4-RD. Expression of CD8α, granzyme A, perforin, and SLAMF7 within the effector memory compartment of CD45RO+ (TEM ) and CD45RA+ effector memory T (TEMRA ) CD4+ cells was quantified by flow cytometry in 18 patients with active IgG4-RD, both at baseline and after 6 months of glucocorticoid treatment. Eighteen healthy subjects were studied as controls. Next-generation sequencing of the T cell receptor α- and β-chain gene was performed on circulating CD4+ CTLs from patients with IgG4-RD before and after treatment and in affected tissues. Circulating CD4+ TEM and TEMRA cells were not expanded in IgG4-RD patients compared to healthy controls. CD4+SLAMF7+ TEM cells (but not TEMRA cells) were significantly increased among IgG4-RD patients. Within CD4+SLAMF7+ TEM cells, CD8α- cells but not CD8αlow cells were elevated in IgG4-RD patients. The same dominant clones of CD8α-CD4+SLAMF7+ TEM cells found in peripheral blood were also identified in affected tissue. CD8α- and CD8αlow CD4+SLAMF7+ TEM cells both expressed cytolytic molecules. Clonally expanded CD8α- but not CD8αlow CD4+SLAMF7+ TEM cells decreased following glucocorticoid-induced disease remission. A subset of CD8α-CD4+SLAMF7+ cytotoxic TEM cells is oligoclonally expanded in patients with active IgG4-RD. This TEM cell population contracts following glucocorticoid-induced remission. Further characterization of this cell population may provide prognostic information and targets for therapeutic intervention.