Role Of CD47 Research Articles

Facilitating cholangiocarcinoma inhibition by targeting CD47

Immune evasion is one of the mechanisms by which cancer cells acquire immunity during cancer development and progression. One of these is the increased expression of cluster of differentiation 47 (CD47), a transmembrane glycoprotein that protects cells from phagocytic elimination. The interaction between CD47 and signal regulatory protein alpha (SIRPα) on macrophages alleviates the phagocytic signal. The present group previously reported high CD47 expression in cholangiocarcinoma (CCA), a major health problem in Thailand and East Asia, and that blocking CD47 using anti-CD47 antibodies promoted the removal of CCA. However, the mechanism through which CD47 inhibition attenuates CCA growth remains unclear. This study explored the clinical significance of targeting CD47 in CCA. Expression levels of CD47 and the macrophage marker CD68 were determined in CCA tissues by immunohistochemistry and correlated with clinical parameters. The role of CD47 in CCA cells was established using CD47-deficient KKU-213A CCA clones in vitro and in vivo. The results showed that CD47 was highly expressed in CCA tissues and significantly correlated with lymph node metastasis (P = 0.038). Moderate-to-dense CD68-positive infiltrating cells in CCA tissues were significantly associated with shorter survival of patients (P = 0.019) and were an independent prognostic factor of CCA patients as determined by the Cox proportional hazard model (hazard ratio, 2.040; 95 % confidence interval, 1.109–3.752; P = 0.022). Three CD47-deficient KKU-213A clones (#19, #23, and #28) were generated. The elimination of CD47 did not affect cell proliferation but increased monocyte-derived macrophage-mediated phagocytosis in vitro. Decreased tumor weights and volumes were observed in mice injected with CD47-deficient CCA clones. This revealed a significant role for CD47 in CCA, with a focus on protecting cancer cells from macrophage phagocytosis.

Single-Cell Analysis Reveals That CD47 mRNA Expression Correlates with Immune Cell Activation, Antiviral Isgs, and Cytotoxicity.

Immune cells are reported to upregulate CD47 during infection, however, the role of CD47 in innate and adaptive immune cells remains unclear. To bridge this knowledge gap, we analysed our single cell (sc)-RNA dataset along with other publicly available sc-RNA datasets from healthy controls, people with HIV-1 (PWH) and COVID-19 patients. We characterized each immune cell based on low, intermediate, and high expression of CD47 . Our analyses revealed that CD47 high pDCs and monocytes exhibited relatively higher expression of IFN-α regulatory genes, antiviral interferon-stimulated genes (ISGs) and MHC-I associated genes compared to CD47 inter. and CD47 low cells. Furthermore, CD47 high NK and CD8+ T cells showed higher expression of antiviral ISGs, as well as genes encoding for cytotoxic markers like granzyme B, perforin, granulysin, interferon gamma and NKG7. Additionally, CD47 high CD8+ T cells expressed higher levels of PD-1 and LAG-3 genes. Lastly, we found that CD47 high B cells had enriched expression of genes involved in cell activation and humoral responses. Overall, our analyses revealed that innate and adaptive immune cells expressing elevated activation and functional gene signatures also express higher CD47 levels.

P-411 CD55 deficiency hinders decidualization in unexplained early miscarriage through the Src/ERK signaling pathway

Abstract Study question What is the role of CD55 in the process of human endometrial stromal cells (HESCs) decidualization in unexplained early miscarriage? Summary answer CD55, responsive to cAMP signaling, is deficient in decidua of patients with unexplained early miscarriage, which hinders decidualization in vitro through perturbing Src/ERK signaling pathway. What is known already Decidualization is a process where HESCs differentiate into decidual stromal cells and present morphological changes and acquisition of secretory function, which is essential for embryo implantation and maintenance of pregnancy while abnormal decidualization contributed to several pregnancy disorders like a miscarriage. Reprogramming of several signaling pathways and transcription factors are involved in this process and cAMP is a critical mediator. Our previous bioinformatic analysis revealed that CD55 was upregulated over five times in the window of implantation, responding to estrogen and progesterone. We speculated that CD55, regulated by cAMP signaling pathway, might play an important role in decidualization. Study design, size, duration Decidua tissues were collected from 8 patients with unexplained early miscarriage and 10 control women with normal early pregnancy undergoing artificial abortion between June 2020 and September 2020. Immortalized HESCs line T-hESCs (ATCC CRL-4003) were cultured for up to 6 days to establish in-vitro decidualization model. Each experiment was conducted in triplicate and replicated at least three times independently. Participants/materials, setting, methods CD55 expression in control and miscarriage decidua was compared by immunohistochemistry and RT-qPCR. T-hESCs were induced into decidualization by medroxyprogesterone acetate (MPA) and 8-Br-cAMP, with prolactin (PRL) and insulin-like growth factor-binding protein 1 (IGFBP1) as decidualization biomarkers. The changes of genes and signaling pathways were detected by RT-qPCR and western blot during decidualization after CD55 knockdown by lentivirus-mediated RNA interference. Signaling pathway disruptors were added to verify the involvement of signaling pathways. Main results and the role of chance The decidua of women with unexplained early miscarriage exhibited decreased expression of CD55, accompanied by a compromised level of decidualization. During in-vitro decidualization, CD55 was significantly upregulated by cAMP in a time- and dose-dependent manner, which was attenuated by a PKA inhibitor H89. Knocking down CD55 expression diminished the expression of decidualization markers PRL and IGFBP1 through inhibition of Src, aberrant activation of ERK and frustrated expression of decidualization-related genes like FOXO1, EGFR, and STAT3. Limitations, reasons for caution The mechanisms revealed in this study were based on in-vitro cell models. It is necessary to verify the significance of CD55 in decidualization with in-vivo models to directly explain the link between CD55, decidualization, and pregnancy loss. Wider implications of the findings CD55 deficiency hinders decidualization through perturbing Src/ERK signaling pathway and expression of decidualization-related genes, potentially contributing to the pathogenesis of spontaneous miscarriage. Progestin supplementation or other factors stimulating cAMP accumulation can restore CD55 expression and improve decidualization, providing a basis for the therapy of spontaneous miscarriage. Trial registration number not applicable

Checkpoint CD24 function on tumor and immunotherapy.

CD24 is a protein found on the surface of cells that plays a crucial role in the proliferation, invasion, and spread of cancer cells. It adheres to cell membranes through glycosylphosphatidylinositol (GPI) and is associated with the prognosis and survival rate of cancer patients. CD24 interacts with the inhibitory receptor Siglec-10 that is present on immune cells like natural killer cells and macrophages, leading to the inhibition of natural killer cell cytotoxicity and macrophage-mediated phagocytosis. This interaction helps tumor cells escape immune detection and attack. Although the use of CD24 as a immune checkpoint receptor target for cancer immunotherapy is still in its early stages, clinical trials have shown promising results. Monoclonal antibodies targeting CD24 have been found to be well-tolerated and safe. Other preclinical studies are exploring the use of chimeric antigen receptor (CAR) T cells, antibody-drug conjugates, and gene therapy to target CD24 and enhance the immune response against tumors. In summary, this review focuses on the role of CD24 in the immune system and provides evidence for CD24 as a promising immune checkpoint for cancer immunotherapy.

An inflammatory response-related gene signature can predict the prognosis and impact the immune infiltration of multiple myeloma

Multiple myeloma (MM) is a highly heterogeneous and incurable disease. Inflammation plays a vital role in cancer genesis and progression. However, the relationship between inflammatory response-related genes (IRRGs) and the prognosis of MM patients remains unknown. We constructed a IRRGs prognosis model by least absolute shrinkage and selection operator regression analysis. Moreover, clinical multivariate regression was performed to identify clinical implications. Gene set enrichment analysis was implemented to conduct its biological properties. CIBERSORT deconvolution algorithm was utilized to calculate the immune cell infiltration in different risk groups. The flow cytometry was utilized to perform protein expression of prognostic gene. A Six-IRRGs (VCAM1, RGS1, KIT, CD81, BLNK, and BIRC3) prognostic risk model was successfully constructed and validated. The risk model was an independent predictor for overall survival. Enrichment analysis revealed autophagy and PI3K–Akt signaling pathways were enriched in the high-risk group. Furthermore, we found CD81 widely impacted on the infiltration of immune cells, especially on monocytes and macrophages2. At last, the role of CD81 in MM was confirmed to be an adverse prognostic factor in clinical. Our study explores the potential application value of IRRGs in MM. These findings may provide new insights into the treatment for MM patients.

The Role of CD47 in Gynecological Oncology

The Role of CD47 in Gynecological Oncology

Tumor-selective Blockade of CD47 Signaling with CD47 Antibody for Enhanced Anti-tumor Activity in Malignant Meningioma.

Patients with WHO grade III meningioma have a poor prognosis with a median survival of less than two years and a high risk of recurrence. However, traditional treatment options have failed to improve prognosis. Therefore, development of novel immunotherapy targets is urgently needed. CD47 acting as a "don't eat me" signal to macrophages can trigger tumor immune escape. However, the role of CD47 in malignant meningioma is not well understood. We collected 190 clinical meningioma samples and detected the expression of CD47 and immune infiltration in WHO grade I-III by immunohistochemistry, western blot, qPCR. We also examined the functional effects of anti-CD47 on cell proliferation, migration and invasion, macrophagemediated phagocytosis and tumorigenicity both in vitro and in vivo. We found that the expression of CD47 was increased in malignant meningioma along with a decreased number of T cells and an increase in CD68+ macrophages. Blocking CD47 with anti-CD47 antibody (B6H12) suppressed tumor cell growth, motility and promoted macrophage-mediated phagocytosis in IOMM-Lee cells in vitro. In vivo experiments showed that anti-CD47 antibody (B6H12 or MIAP301) significantly inhibited the tumor growth and this effect was partly blocked by the depletion of macrophages. Finally, p-ERK and EGFR showed higher expression in malignant meningioma with high expression of CD47, which was verified by western blot. Our results demonstrated that CD47 maybe involved in the meningioma progression and prognosis and offered a novel therapeutic option by targeting CD47 in malignant meningioma.

The role of CD24 as a potential biomarker for malignant pleural mesothelioma

Abstract Objectives Pleural mesothelioma is a rapidly progressing pleural neoplasm caused by asbestos exposure of a long latency around 30-40 years. Patients with mesothelioma are usually diagnosed at a late stage with poor outcomes in terms of morbidity and mortality with 6–12 months’ median survival. Despite the prohibited use of asbestos, malignant pleural mesothelioma is still increasingly being occurred in young age and female patients. Different un-standardized biomarkers have been used to diagnose MPM as mesothelin and febulin with controversial results, so we used CD 24 as a biomarker to diagnose and differentiate between different subtypes of malignant pleural mesothelioma. Materials and methods Our cohort study included total of fifty-nine patients with exudative pleural effusion. All patients underwent full history taking, clinical examination, blood tests (CBC, coagulation profile, liver and kidney functions), tapping of pleural effusion and to send pleural fluid investigations for LDH, albumin, total protein and albumin, then confirmed exudative pleural effusion patients were subjected to thoracic ultrasonography and medical thoracoscopy for the majority of cases or ultrasound guided biopsy in selected cases to obtain pleural biopsies for histopathology and then the examination of pleural biopsies for CD24 expression. Results Our study demonstrated the possibility of using CD24 as a biomarker in the immunostaining of pleural biopsies to differentiate between malignant pleural mesothelioma and pleural malignancy other than mesothelioma (18 mesothelioma cases versus 2 nonmesothelioma malignant cases) with high statistical significance P value < 0.001 and also it can discriminate between subtypes of mesothelioma as it showed marked significance in epithelioid subtype (12 epithelioid versus 1 sarcomatoid versus 5 biphasic subtypes) with more uptake by score +2 in epithelioid mesothelioma. Conclusions CD24 can be supposed to be a routine biomarker for immunohistochemistry of pleural tissue samples in diagnosis of mesothelioma and it can be used to differentiate between subtypes of malignant mesothelioma subtypes.

Latest Findings on the Role of CD47 in Tumor Immune Evasion and Related Targeted Therapies

CD47 is an immunoglobulin that is overexpressed on the surface of a variety of cancer cells. CD47 forms a signaling complex with signal regulatory protein alpha (SIRPα), prompting the escape of cancer cells from macrophage-mediated phagocytosis. In recent years, CD47 has been shown to be highly expressed in many types of solid tumors and is associated with poor prognosis in patients. More and more studies have shown that inhibition of the CD47-SIRPα signaling pathway can promote adaptive immune responses and enhance the phagocytosis of tumor cells by macrophages. Humanized anti-CD47 IgG4 monoclonal antibody has been studied in clinical trials for the treatment of a variety of advanced solid tumors and lymphomas, demonstrating a sound safety profile and achieving partial remission in some patients. In this review we discuss the structure and function of CD47 and the mechanism of CD47 regulation in tumors, summarize the research progress in therapeutic antibody drugs targeting CD47 and a bottleneck in research that targeted drugs are more prone to result in serious adverse effects, and evaluated the potential of the applying CD47-SIRPα signaling pathway in anti-cancer therapy.

Dendritic cell expression of CD24 contributes to optimal priming of T lymphocytes in lymph nodes.

CD24 is a GPI anchored cell surface glycoprotein whose function as a co-stimulatory molecule has been implicated. However, the function of CD24 on antigen presenting cells during T cell responses is not well understood. Here we show that in the CD24-deficient host, adoptively transferred CD4+ T cells undergo inefficient expansion and have accelerated cell death in lymph nodes, which results in insufficient priming of T cells. Insufficient expansion of T cells in the CD24-deficient host was not due to host anti-CD24 response by NK, T and B lymphocytes. Transgenic expression of CD24 on DC in CD24-/- mice restored T cell accumulation and survival in draining lymph nodes. Consistent with these findings, MHC II tetramer staining also revealed that an antigen-specific polyclonal T cell response was reduced in lymph nodes of CD24-/- mice. Taken together, we have revealed a novel role of CD24 on DC in optimal T cell priming in lymph nodes. These data suggest that CD24 blockade should lower unwanted T cell responses such as those in autoimmune diseases.

CD47 expression is critical for CAR T-cell survival in vivo

BackgroundCD47 is an attractive immunotherapeutic target because it is highly expressed on multiple solid tumors. However, CD47 is also expressed on T cells. Limited studies have evaluated CD47-chimeric antigen receptor...

CD47 antisense oligonucleotide treatment attenuates obesity and its-associated metabolic dysfunction

Previous study from our lab has revealed a new role of CD47 in regulating adipose tissue function, energy homeostasis and the development of obesity and metabolic disease in CD47 deficient mice. In this study, the therapeutic potential of an antisense oligonucleotide (ASO) targeting to CD47 in obesity and its-associated complications was determined in two obese mouse models (diet induced and genetic models). In diet induced obesity, male C57BL6 mice were fed with high fat (HF) diet to induce obesity and then treated with CD47ASO or control ASO for 8 weeks. In genetic obese mouse model, male six-week old ob/ob mice were treated with ASOs for 9 weeks. We found that CD47ASO treatment reduced HF diet-induced weight gain, decreased fat mass, prevented dyslipidemia, and improved glucose tolerance. These changes were accompanied by reduced inflammation in white adipose tissue and decreased hepatic steatosis. This protection was also seen in CD47ASO treated ob/ob mice. Mechanistically, CD47ASO treatment increased mice physical activity and energy expenditure, contributing to weight loss and improved metabolic outcomes in obese mice. Collectively, these findings suggest that CD47ASO might serve as a new treatment option for obesity and its-associated metabolic complications.

Abstract 6150: Potential role of CD47 in T cell exhaustion program

Abstract Multiple suppressive mechanisms within the tumor microenvironment (TME) are capable of blunting anti-tumor T cell responses. These include engagement of inhibitory receptors expressed in tumor-associated, exhausted CD8 T cells, such as programmed cell death protein 1 (PD-1), T-cell immunoglobulin and mucin-domain containing-3 (TIM-3), lymphocyte-activation gene 3 (LAG-3), 2B4 (also known as CD244), and T cell immunoreceptor with Ig and ITIM domains (TIGIT). While immune checkpoint blockade therapies aimed at reversing the dysfunctional state of tumor-associated T cells have demonstrated clinical effectiveness, not all cancer patients achieve long-term disease control. This is due, at least in part, to the refractory nature of what are categorized as terminally exhausted CD8 T cells to be reinvigorated by, for example, PD-1/PD-L1 blockade. As CD8 T cell exhaustion (or dysfunction) is a major therapeutic challenge, gaps in our understanding of cellular and molecular mechanisms underlying the T cell exhaustion (or dysfunction) program in cancer warrant further study of pathways that program T cells toward exhaustion (or dysfunction). Through comprehensive immune profiling of tumor-infiltrating T lymphocytes (TILs), we found that CD47 expression in CD8 TILs isolated from melanoma patients significantly correlates with expression of several checkpoint inhibitory molecules (e.g., TIM-3, PD-1 and LAG-3). Additionally, our re-analysis of single cell data from melanoma patients revealed that terminally exhausted T cells (Tex) and TCF7hi Tex precursor cells exhibit high levels of CD47 transcripts, suggesting phenotypic association of CD47 with T cell exhaustion. We confirmed our observations in murine B16-F10 melanoma where CD47 expression is significantly upregulated in exhausted CD8 TILs. We also show that CD47 functions as a negative regulator for T cell proliferation and function during T cell priming. To address the role of CD47 during the development of CD8 T cell exhaustion/dysfunction in cancer, we performed adoptive T cell transfer of the naïve-sorted Cd47+/+ (WT) and Cd47+/- (Het) antigen specific Pmel-1 CD8 T cells (but not Cd47-deficient Pmel-1 CD8 T cells as they would be subject to innate immune clearance) into B16 tumor-bearing mice and found that Cd47-Het Pmel-1 CD8 TILs, as compared to the Cd47-WT Pmel-1 CD8 TILs, exhibit less expression of exhaustion-related genes (e.g. Pdcd1, Lag3 and Tox), and increased expression of genes associated with T cell activation and proliferation (e.g. Mki67, Lck, Cd69, Gzma, Gzmk). We further confirmed that thrombospondin-1 (TSP-1), as an extracellular matrix protein and a ligand of CD47, contributes to driving the differentiation of CD8 T cells toward exhaustion. Our data highlight for the first time the potential of extracellular matrix protein TSP-1 in programming CD8 T cell exhaustion in cancer through its interaction with CD47 expressed on CD8 T cells. Citation Format: Chien-Huan Weng, Fadi Samaan, Sadna Budhu, Levi Mangarin, Sébastien Monette, Cailian Liu, Stephane Pourpe, Linda Hamadene, Hong Zhong, Xia Yang, David Schroder, Roberta Zappasodi, Pamela Holland, Jedd D. Wolchok, Taha Merghoub. Potential role of CD47 in T cell exhaustion program [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6150.

Role of CD47 in tumor immunity: a potential target for combination therapy

CD47 performs a vital function in cancer therapy by binding to different SIRPα, thrombospondin 1, and integrin. However, its role in tumor immunity and its correlation with prognosis among many cancer types remain unknown. The raw mRNA expression data of CD47 in cancer patients was downloaded from TCGA and GTEx datasets. The protein expression of CD47 was detected using a microarray. Kaplan Meier analysis and forest plot were performed to compare the effects of high and low expression of CD47 on overall survival in different cancers. In addition, the correlations between CD47 expression and immune cell infiltration, stromal components, immune checkpoint genes, tumor mutational burden (TMB), and microsatellite instability (MSI) were analyzed from the public database. The gene function was determined by Gene Set Enrichment Analysis (GSEA). The expressions of CD47 in CHOL, COAD, ESCA, HNSC, KIRC, STAD, and THCA were higher compared with normal tissues. Elevated expression of CD47 predicted poor prognosis in ACC, KICH, KIRP, LGG, PAAD and UCEC. CD47 expression was strongly associated with immune infiltrating cells among KICH, KIRP, LGG, and PAAD. In addition, significant positive correlations with most immune checkpoint genes including PDCD 1 (PD-1), CD274 (PD-L1), CTLA4 in BLCA, DLBC, KICH, KIRC, LUAD, LUSC, PAAD, PCPG, SKCM, STAD, UCEC, and UVM was noted for the expression of CD47. GSEA analysis demonstrated that CD47 was a key regulator in metabolism-related pathways. These findings provide novel evidence that CD47 could be utilized as a promising prognostic biomarker and combination treatment target in various cancers.

Research Progress of CD47-Related Signaling Pathway and the Role of CD47 in Pathogenic Infection

CD47, a transmembrane glycoprotein widely expressed on the cell surface, is one of the important checkpoints through which cells escape innate immune surveillance. The important role of CD47-related signaling pathway and changes in expression level in immune regulation, pathogen infection and anti-tumor immunity has gradually come to be recognized. We reviewed herein the structure and biological characteristics of CD47, the interaction and the downstream signaling of CD47 with integrin, thrombospondin 1, and signal regulatory protein, and the upregulated expression of CD47 induced by the infection of different pathogens and the role of CD47 in different types of immune response to infection. Discussions were made regarding the prospective application of CD47 targeted immunotherapy in pathogenic infection-related cancers, intending to provide guidance for future research.

CD47 antibody protects mice from doxorubicin-induced myocardial damage by suppressing cardiomyocyte apoptosis.

Cluster of differentiation 47 (CD47) is upregulated in mouse models of doxorubicin (Dox)-induced dilated cardiomyopathy (DCM). To explore the role of CD47 in the development of DCM, in the present study, CD47 signaling was blocked by an anti-CD47 neutralizing antibody (aCD47) in mice with Dox-induced DCM. Intraperitoneal (i.p.) administration of 10 mg/kg Dox once a week significantly induced the development of DCM after 4 weeks, which was accompanied by the upregulation of CD47 expression in heart tissues. However, co-administration of Dox with 7 mg/kg aCD47 once a week significantly reduced the severity of DCM, with lower numbers of disordered and broken myofibers, reduced cardiomyocytes and infiltration of macrophages in the heart tissues of treated mice. The beneficial effects were associated with the reduced population of Annexin V+7-AAD- apoptotic cells, and the attenuated formation of interstitial fibrosis and release of lactate dehydrogenase (LDH) in the aCD47-treated mice. In addition, co-administration with aCD47 effectively reduced the expression of Bax, collagen I, interleukin (IL)-6 and tumor necrosis factor (TNF)-α in murine DCM. These results were further supported by an in vitro study, in which aCD47 pre-treatment significantly reduced the Dox-induced early apoptosis of cardiomyocytes and suppressed the expression of Bax, cleaved caspase-1/3 and phosphorylation of p38 MAPK. Therefore, aCD47 attenuated DCM in mice, possibly by suppressing cardiomyocyte early apoptosis and p38 MAPK signaling. CD47 may be a useful therapeutic target in the treatment of DCM.

The expression and clinical significance of CD59 and FLAER in Chinese adult AML patients.

BackgroundThe role of CD59 and fluorescently labeled aerolysin (FLAER) in acute myeloid leukemia (AML) remains unclear and requires further investigation. To explore the relationship between CD59, FLAER, and AML, we investigated CD59 and FLAER expression in AML and analyzed their relationship with clinical characteristics of AML patients.MethodsWe employed flow cytometry (FCM) to analyze CD59 and FLAER expression in 161 AML patients at Tianjin Medical University General Hospital and evaluated its association with sex, white blood cell (WBC) count, platelet (PLT) count, thrombin time (TT), prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen (FIB), D‐Dimer(D‐D), and lactate dehydrogenase (LDH), followed by analyzing its connection with disease progression and complete remission (CR).ResultsCD59 and FLAER deficiencies were identified in AML patients. Compared with CR group, non‐CR group patients revealed more CD59 and FLAER deficiency. Compared with non‐acute promyelocytic leukemia (M3) group, M3 group patients had more CD59 and FLAER deficiency. CD59− level in primordial cells of M3 patients was positively correlated with primordial cell ratio (r = 0.660, p = 0.003). Additionally, we discovered that the decline in CD59 and FLAER levels might be linked to higher D‐D and LDH in AML patients. The difference was statistically significant (p < 0.05).ConclusionsWe demonstrated that the decline in CD59 and FLAER levels was associated with leukemia cell proliferation and abnormal coagulation function in AML, suggesting that they could serve as a predictor of AML coagulation dysfunction, particularly in M3.

Expression of CD47 in the pancreatic β-cells of people with recent-onset type 1 diabetes varies according to disease endotype.

We are studying the dialogue between β-cells and the immune system in type 1 diabetes and have identified a cell surface receptor, signal regulatory protein-alpha (SIRPα) as an important component in the regulation of β-cell survival. SIRPα interacts with another protein, CD47, to mediate signalling. In the present work, we have studied the expression and role of CD47 in human islet cells in type 1 diabetes. Clonal EndoC-βH1 cells were employed for functional studies. Cells were exposed to pro-inflammatory cytokines and their viability monitored by flow cytometry after staining with propidium iodide. Targeted knockdown of CD47 or SIRPα was achieved with small interference RNA molecules and the expression of relevant proteins studied by Western blotting or immunocytochemistry. Human pancreas sections were selected from the Exeter Archival Diabetes Biobank and used to examine the expression of CD47 by immunofluorescence labelling. Image analysis was employed to quantify expression. CD47 is abundantly expressed in both α and β cells in human pancreas. In type 1 diabetes, the levels of CD47 are increased in α cells across all age groups, whereas the expression in β-cells varies according to disease endotype. Knockdown of either CD47 or SIRPα in EndoC-βH1 cells resulted in a loss of viability. We conclude that the CD47 plays a previously unrecognised role in the regulation of β-cell viability. This system is dysregulated in type 1 diabetes suggesting that it may be targeted therapeutically to slow disease progression.

The Cromer blood group system: an update.

Abstract This update of the Cromer (CROM) blood group system (Storry JR, Reid ME, Yazer MH. The Cromer blood group system: a review. Immunohematology 2010;26:109–17) includes additional variants to the Cromer system (ISBT021), both new antigens and new molecular bases underlying the null phenotype. The molecule on which the Cromer blood group antigens are carried, CD55 (DAF), is an important receptor for the malaria parasite, Plasmodium falciparum, and the role of CD55 in health and disease continues to expand.

Abstract MP04: Single Cell Profiling Identifies IgM To MDA-LDL Producing Human B Cells And Atheroprotective Role Of CD24

Murine B-1 cells produce IgMs that inactivate oxidation-specific epitopes and protect against atherosclerosis. Despite compelling data that IgM to MDA-LDL (IgM MDA-LDL ) is inversely associated with coronary artery disease (CAD) and cardiovascular (CV) events in human, the human B cell subtype that produces IgM MDA-LDL is unknown. Here, we utilized mass cytometry to identify the 11 circulating human B cell subtypes and discovered that only the frequency of CD20 + CD27 + IgM + cells was associated with IgM MDA-LDL levels. Notably, high expression of CD24, a GPI-anchored sialoglycoprotein, was associated with IgM MDA-LDL (r = 0.57, p = 0.002) and inversely associated with CAD severity (r = -0.58, p=0.001). Adoptive transfer (AT) of sorted CD20 + CD27 + IgM + CD24hi (B 27+IgM+CD24hi ) and CD24lo/- (B 27+IgM+CD24lo/- ) human B cells into humanized mice demonstrated that CD24 is critical for trafficking to the spleen and IgM production. Bulk RNAseq coupled with pathway analysis of B 27+IgM+CD24hi and B 27+IgM+CD24lo/- cells revealed enhanced BCR and CCR6 signaling in B 27+IgM+CD24hi . Imaging flow cytometry indicated colocalization between CD24 and CCR6 which was abrogated by CD24 blocking antibody (CD24mAb). Trans-well migration and internalization assays demonstrated that CD24 blockade increased CCL20-induced CCR6 internalization (p &lt; 0.05, n =4), and reduced CCL20-induced migration of B 27+IgM+CD24hi cells (p &lt; 0.05, n =4). CD24mAb treatment of B 27+IgM+CD24hi cells prior to AT into humanized mice also reduced the amount of surface CCR6 on B 27+IgM+CD24hi cells in vivo (p &lt; 0.05, n = 4). Both CCR6 knockout and CD24 inhibition of B 27+IgM+CD24hi cells reduced migration to the spleen (p &lt; 0.05, n = 4), and plasma level of human IgM (p = 0.057, n = 4). Lastly, single cell multi-omics sequencing of PBMCs from 60 CAD subjects revealed elevated CCR6 and IgM signaling in B 27+IgM+CD24hi cells in subjects with less severe CAD. Results provide the first evidence for a role for CD24 in regulating CCR6-mediated B cell homing to the spleen, IgM production and CAD in humans. Findings may have important implications for the new CD24 immunotherapy entering clinical trials and raise the possibility that augmenting CD24 and/or CCR6 on B 27+IgM+ cells may be an effective atheroprotective strategy.