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Wang P, Song Y, Li H, Zhuang J, Shen X, Yang W, Mi R, Lu Y, Yang B, Ma M, Shen H. SIRPA enhances osteosarcoma metastasis by stabilizing SP1 and promoting SLC7A3-mediated arginine uptake. Cancer Lett 2023; 576:216412. [PMID: 37769797 DOI: 10.1016/j.canlet.2023.216412] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Revised: 09/08/2023] [Accepted: 09/23/2023] [Indexed: 10/03/2023]
Abstract
The function of signal regulatory protein alpha (SIRPA) has been well studied in macrophages and dendritic cells, but relatively less in tumors. Notably, SIRPA is upregulated in osteosarcoma tissues, particularly in metastatic tissues, and is associated with unfavorable clinical outcomes. Knockdown of SIRPA impaired OS cell migration by decreasing specificity protein 1 (SP1) stability and arginine uptake. Importantly, SIRPA phosphorylated SP1 at threonine 278 (Thr278) through extracellular signal-regulated kinase (ERK) activation to protect SP1 from proteasomal degradation. In addition, SP1 increased solute carrier family 7 member 3 (SLC7A3) expression by binding to the SLC7A3 promoter and increased the capability of arginine uptake, thereby facilitating OS cell migration. More interestingly, arginine promoted the stability of SP1 in an ERK-independent manner and thus formed the "SP1 stabilization circle". Combined treatment with the anti-SIRPA antibody and arginase, which blocked the circle, impaired tumor metastasis in mice bearing xenografts formed from SIRPA-overexpressing cells. In summary, our study demonstrates that the upregulation of SIRPA promotes OS metastasis via the "SP1 stabilization circle" and SLC7A3-mediated arginine uptake, which might serve as a target for OS treatment.
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Affiliation(s)
- Peng Wang
- Department of Orthopedics, The Eighth Affliated Hospital, Sun Yat-sen University, No. 3025 Shennan Zhong Road, Shenzhen, Guangdong, 518033, China
| | - Yihui Song
- Department of Orthopedics, The Eighth Affliated Hospital, Sun Yat-sen University, No. 3025 Shennan Zhong Road, Shenzhen, Guangdong, 518033, China
| | - Hongyu Li
- Department of Orthopedics, The Eighth Affliated Hospital, Sun Yat-sen University, No. 3025 Shennan Zhong Road, Shenzhen, Guangdong, 518033, China
| | - Jiahao Zhuang
- Department of Orthopedics, The Eighth Affliated Hospital, Sun Yat-sen University, No. 3025 Shennan Zhong Road, Shenzhen, Guangdong, 518033, China
| | - Xin Shen
- Department of Orthopedics, The Eighth Affliated Hospital, Sun Yat-sen University, No. 3025 Shennan Zhong Road, Shenzhen, Guangdong, 518033, China
| | - Wen Yang
- Department of Orthopedics, The Eighth Affliated Hospital, Sun Yat-sen University, No. 3025 Shennan Zhong Road, Shenzhen, Guangdong, 518033, China
| | - Rujia Mi
- Center for Biotherapy, The Eighth Affliated Hospital, Sun Yat-sen University, No. 3025 Shennan Zhong Road, Shenzhen, Guangdong, 518033, China
| | - Yixuan Lu
- Center for Biotherapy, The Eighth Affliated Hospital, Sun Yat-sen University, No. 3025 Shennan Zhong Road, Shenzhen, Guangdong, 518033, China
| | - Biao Yang
- Department of Orthopedics, The Eighth Affliated Hospital, Sun Yat-sen University, No. 3025 Shennan Zhong Road, Shenzhen, Guangdong, 518033, China
| | - Mengjun Ma
- Department of Orthopedics, The Eighth Affliated Hospital, Sun Yat-sen University, No. 3025 Shennan Zhong Road, Shenzhen, Guangdong, 518033, China.
| | - Huiyong Shen
- Department of Orthopedics, The Eighth Affliated Hospital, Sun Yat-sen University, No. 3025 Shennan Zhong Road, Shenzhen, Guangdong, 518033, China.
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Ahmed MSU, Lord BD, Adu Addai B, Singhal SK, Gardner K, Salam AB, Ghebremedhin A, White J, Mahmud I, Martini R, Bedi D, Lin H, Jones JD, Karanam B, Dean-Colomb W, Grizzle W, Wang H, Davis M, Yates CC. Immune Profile of Exosomes in African American Breast Cancer Patients Is Mediated by Kaiso/THBS1/CD47 Signaling. Cancers (Basel) 2023; 15:cancers15082282. [PMID: 37190208 DOI: 10.3390/cancers15082282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2022] [Revised: 04/02/2023] [Accepted: 04/04/2023] [Indexed: 05/17/2023] Open
Abstract
African American (AA) women with breast cancer are more likely to have higher inflammation and a stronger overall immune response, which correlate with poorer outcomes. In this report, we applied the nanostring immune panel to identify differences in inflammatory and immune gene expression by race. We observed a higher expression of multiple cytokines in AA patients compared to EA patients, with high expression of CD47, TGFB1, and NFKB1 associated with the transcriptional repressor Kaiso. To investigate the mechanism associated with this expression pattern, we observed that Kaiso depletion results in decreased expression of CD47, and its ligand SIRPA. Furthermore, Kaiso appears to directly bind to the methylated sequences of the THBS1 promotor and repress gene expression. Similarly, Kaiso depletion attenuated tumor formation in athymic nude mice, and these Kaiso-depleted xenograft tissues showed significantly higher phagocytosis and increased infiltration of M1 macrophages. In vitro validation using MCF7 and THP1 macrophages treated with Kaiso-depleted exosomes showed a reduced expression of immune-related markers (CD47 and SIRPA) and macrophage polarization towards the M1 phenotype compared to MCF7 cells treated with exosomes isolated from high-Kaiso cells. Lastly, analysis of TCGA breast cancer patient data demonstrates that this gene signature is most prominent in the basal-like subtype, which is more frequently observed in AA breast cancer patients.
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Affiliation(s)
- Md Shakir Uddin Ahmed
- Department of Biology and Center for Cancer Research, Tuskegee University, Tuskegee, AL 36088, USA
- Bangladesh Council of Scientific and Industrial Research, Dhaka 1205, Bangladesh
| | - Brittany D Lord
- Department of Genetics, University of Georgia, Athens, GA 30602, USA
| | - Benjamin Adu Addai
- School of Veterinary Medicine, Tuskegee University, Tuskegee, AL 36088, USA
| | - Sandeep K Singhal
- Department of Pathology, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND 58202, USA
- Department of Biomedical Engineering, School of Electrical Engineering and Computer Science, University of North Dakota, Grand Forks, ND 58202, USA
| | - Kevin Gardner
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY 10032, USA
| | - Ahmad Bin Salam
- Department of Biology and Center for Cancer Research, Tuskegee University, Tuskegee, AL 36088, USA
| | - Anghesom Ghebremedhin
- Department of Biology and Center for Cancer Research, Tuskegee University, Tuskegee, AL 36088, USA
| | - Jason White
- Department of Biology and Center for Cancer Research, Tuskegee University, Tuskegee, AL 36088, USA
| | - Iqbal Mahmud
- Department of Pathology, Immunology and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Rachel Martini
- Department of Surgery, Weill Cornell Medicine, New York, NY 10065, USA
| | - Deepa Bedi
- Department of Biology and Center for Cancer Research, Tuskegee University, Tuskegee, AL 36088, USA
| | - Huixian Lin
- Department of Biology and Center for Cancer Research, Tuskegee University, Tuskegee, AL 36088, USA
| | - Jacqueline D Jones
- Department of Biological and Environmental Sciences, Troy University, Troy, AL 36082, USA
| | | | - Windy Dean-Colomb
- Department of Biology and Center for Cancer Research, Tuskegee University, Tuskegee, AL 36088, USA
- Piedmont Oncology-Newnan, Newnan, GA 30265, USA
| | - William Grizzle
- Department of Pathology, School of Medicine, The University of Alabama at Birmingham, Birmingham, AL 35233, USA
| | - Honghe Wang
- Department of Biology and Center for Cancer Research, Tuskegee University, Tuskegee, AL 36088, USA
| | - Melissa Davis
- Department of Surgery, Weill Cornell Medicine, New York, NY 10065, USA
| | - Clayton C Yates
- Department of Biology and Center for Cancer Research, Tuskegee University, Tuskegee, AL 36088, USA
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
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3
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Miyazaki T, Kanatsu-Shinohara M, Ema M, Shinohara T. Signal regulatory protein alpha is a conserved marker for mouse and rat spermatogonial stem cells. Biol Reprod 2023; 108:682-693. [PMID: 36648447 DOI: 10.1093/biolre/ioad006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 12/08/2022] [Accepted: 01/10/2023] [Indexed: 01/18/2023] Open
Abstract
Characterization of spermatogonial stem cells (SSCs) has been hampered by their low frequency and lack of features that distinguish them from committed spermatogonia. Few conserved SSC markers have been discovered. To identify a new SSC marker, we evaluated SIRPA expression in mouse and rat SSCs. SIRPA was expressed in a small population of undifferentiated spermatogonia. SIRPA and its ligand CD47 were expressed in cultured SSCs. Expression of both SIRPA and CD47 was upregulated by supplementation of GDNF and FGF2, which promoted SSC self-renewal. Sirpa depletion by short hairpin RNA impaired the proliferation of cultured SSCs, and these cells showed decreased MAP2K1 activation and PTPN11 phosphorylation. Immunoprecipitation experiments showed that SIRPA associates with PTPN11. Ptpn11 depletion impaired SSC activity in a manner similar to Sirpa depletion. SIRPA was expressed in undifferentiated spermatogonia in rat and monkey testes. Xenogenic transplantation experiments demonstrated that SIRPA is expressed in rat SSCs. These results suggest that SIRPA is a conserved SSC marker that promotes SSC self-renewal division by activating the MAP2K1 pathway via PTPN11.
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Affiliation(s)
- Takehiro Miyazaki
- Department of Molecular Genetics, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan
| | - Mito Kanatsu-Shinohara
- Department of Molecular Genetics, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan.,AMED-CREST, AMED 1-7-1 Otemachi, Chiyodaku, Tokyo 100-0004, Japan
| | - Masatsugu Ema
- Research Center for Animal Life Science, Shiga University of Medical Science, Seta-Tsukinowa-cho, Otsu, Shiga 520-2192, Japan
| | - Takashi Shinohara
- Department of Molecular Genetics, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan
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Dehmani S, Nerrière-Daguin V, Néel M, Elain-Duret N, Heslan JM, Belarif L, Mary C, Thepenier V, Biteau K, Poirier N, Blancho G, Haspot F. SIRPγ-CD47 Interaction Positively Regulates the Activation of Human T Cells in Situation of Chronic Stimulation. Front Immunol 2021; 12:732530. [PMID: 34925315 PMCID: PMC8671138 DOI: 10.3389/fimmu.2021.732530] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 10/05/2021] [Indexed: 11/16/2022] Open
Abstract
A numerous number of positive and negative signals via various molecules modulate T-cell activation. Within the various transmembrane proteins, SIRPγ is of interest since it is not expressed in rodents. SIRPγ interaction with CD47 is reevaluated in this study. Indeed, we show that the anti-SIRPγ mAb clone LSB2.20 previously used by others has not been appropriately characterized. We reveal that the anti-SIRPα clone KWAR23 is a Pan anti-SIRP mAb which efficiently blocks SIRPα and SIRPγ interactions with CD47. We show that SIRPγ expression on T cells varies with their differentiation and while being expressed on Tregs, is not implicated in their suppressive functions. SIRPγ spatial reorganization at the immune synapse is independent of its interaction with CD47. In vitro SIRPα-γ/CD47 blockade with KWAR23 impairs IFN-γ secretion by chronically activated T cells. In vivo in a xeno-GvHD model in NSG mice, the SIRPγ/CD47 blockade with the KWAR23 significantly delays the onset of the xeno-GvHD and deeply impairs human chimerism. In conclusion, we have shown that T-cell interaction with CD47 is of importance notably in chronic stimulation.
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Affiliation(s)
- Safa Dehmani
- OSE Immunotherapeutics, Nantes, France.,Nantes Université, Inserm, Centre de Recherche en Transplantation et Immunologie, Unité Mixte de Recherche (UMR) 1064, Institut de Transplantation Urologie-Néphrologie (ITUN), Nantes, France
| | - Véronique Nerrière-Daguin
- Nantes Université, Inserm, Centre de Recherche en Transplantation et Immunologie, Unité Mixte de Recherche (UMR) 1064, Institut de Transplantation Urologie-Néphrologie (ITUN), Nantes, France
| | - Mélanie Néel
- Nantes Université, Inserm, Centre de Recherche en Transplantation et Immunologie, Unité Mixte de Recherche (UMR) 1064, Institut de Transplantation Urologie-Néphrologie (ITUN), Nantes, France
| | - Nathan Elain-Duret
- Nantes Université, Inserm, Centre de Recherche en Transplantation et Immunologie, Unité Mixte de Recherche (UMR) 1064, Institut de Transplantation Urologie-Néphrologie (ITUN), Nantes, France
| | - Jean-Marie Heslan
- Nantes Université, Inserm, Centre de Recherche en Transplantation et Immunologie, Unité Mixte de Recherche (UMR) 1064, Institut de Transplantation Urologie-Néphrologie (ITUN), Nantes, France
| | | | | | | | | | | | - Gilles Blancho
- Nantes Université, Inserm, Centre de Recherche en Transplantation et Immunologie, Unité Mixte de Recherche (UMR) 1064, Institut de Transplantation Urologie-Néphrologie (ITUN), Nantes, France
| | - Fabienne Haspot
- Nantes Université, Inserm, Centre de Recherche en Transplantation et Immunologie, Unité Mixte de Recherche (UMR) 1064, Institut de Transplantation Urologie-Néphrologie (ITUN), Nantes, France
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5
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Sharp RC, Brown ME, Shapiro MR, Posgai AL, Brusko TM. The Immunoregulatory Role of the Signal Regulatory Protein Family and CD47 Signaling Pathway in Type 1 Diabetes. Front Immunol 2021; 12:739048. [PMID: 34603322 PMCID: PMC8481641 DOI: 10.3389/fimmu.2021.739048] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 08/31/2021] [Indexed: 12/11/2022] Open
Abstract
Background The pathogenesis of type 1 diabetes (T1D) involves complex genetic susceptibility that impacts pathways regulating host immunity and the target of autoimmune attack, insulin-producing pancreatic β-cells. Interactions between risk variants and environmental factors result in significant heterogeneity in clinical presentation among those who develop T1D. Although genetic risk is dominated by the human leukocyte antigen (HLA) class II and insulin (INS) gene loci, nearly 150 additional risk variants are significantly associated with the disease, including polymorphisms in immune checkpoint molecules, such as SIRPG. Scope of Review In this review, we summarize the literature related to the T1D-associated risk variants in SIRPG, which include a protein-coding variant (rs6043409, G>A; A263V) and an intronic polymorphism (rs2281808, C>T), and their potential impacts on the immunoregulatory signal regulatory protein (SIRP) family:CD47 signaling axis. We discuss how dysregulated expression or function of SIRPs and CD47 in antigen-presenting cells (APCs), T cells, natural killer (NK) cells, and pancreatic β-cells could potentially promote T1D development. Major Conclusions We propose a hypothesis, supported by emerging genetic and functional immune studies, which states a loss of proper SIRP:CD47 signaling may result in increased lymphocyte activation and cytotoxicity and enhanced β-cell destruction. Thus, we present several novel therapeutic strategies for modulation of SIRPs and CD47 to intervene in T1D.
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Affiliation(s)
- Robert C Sharp
- Department of Pathology, Immunology, and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL, United States
| | - Matthew E Brown
- Department of Pathology, Immunology, and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL, United States
| | - Melanie R Shapiro
- Department of Pathology, Immunology, and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL, United States
| | - Amanda L Posgai
- Department of Pathology, Immunology, and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL, United States
| | - Todd M Brusko
- Department of Pathology, Immunology, and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL, United States.,Department of Pediatrics, College of Medicine, Diabetes Institute, University of Florida, Gainesville, FL, United States
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6
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Morrissey MA, Kern N, Vale RD. CD47 Ligation Repositions the Inhibitory Receptor SIRPA to Suppress Integrin Activation and Phagocytosis. Immunity 2020; 53:290-302.e6. [PMID: 32768386 PMCID: PMC7453839 DOI: 10.1016/j.immuni.2020.07.008] [Citation(s) in RCA: 97] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Revised: 05/19/2020] [Accepted: 07/10/2020] [Indexed: 01/29/2023]
Abstract
CD47 acts as a "don't eat me" signal that protects cells from phagocytosis by binding and activating its receptor SIPRA on macrophages. CD47 suppresses multiple different pro-engulfment "eat me" signals, including immunoglobulin G (IgG), complement, and calreticulin, on distinct target cells. This complexity has limited understanding of how the "don't eat me" signal is transduced biochemically. Here, we utilized a reconstituted system with a defined set of signals to interrogate the mechanism of SIRPA activation and its downstream targets. CD47 ligation altered SIRPA localization, positioning SIRPA for activation at the phagocytic synapse. At the phagocytic synapse, SIRPA inhibited integrin activation to limit macrophage spreading across the surface of the engulfment target. Chemical reactivation of integrin bypassed CD47-mediated inhibition and rescued engulfment, similar to the effect of a CD47 function-blocking antibody. Thus, the CD47-SIRPA axis suppresses phagocytosis by inhibiting inside-out activation of integrin signaling in the macrophage, with implications to cancer immunotherapy applications.
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Affiliation(s)
- Meghan A Morrissey
- Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, CA 94158, USA; Howard Hughes Medical Institute, University of California San Francisco, San Francisco, CA 94158, USA
| | - Nadja Kern
- Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, CA 94158, USA; Howard Hughes Medical Institute, University of California San Francisco, San Francisco, CA 94158, USA
| | - Ronald D Vale
- Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, CA 94158, USA; Howard Hughes Medical Institute, University of California San Francisco, San Francisco, CA 94158, USA.
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Boettcher AN, Cunnick JE, Powell EJ, Egner TK, Charley SE, Loving CL, Tuggle CK. Porcine signal regulatory protein alpha binds to human CD47 to inhibit phagocytosis: Implications for human hematopoietic stem cell transplantation into severe combined immunodeficient pigs. Xenotransplantation 2018; 26:e12466. [PMID: 30311702 DOI: 10.1111/xen.12466] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 08/10/2018] [Accepted: 09/18/2018] [Indexed: 12/27/2022]
Abstract
BACKGROUND Severe combined immunodeficient (SCID) pigs are an emerging animal model being developed for biomedical and regenerative medicine research. SCID pigs can successfully engraft human-induced pluripotent stem cells and cancer cell lines. The development of a humanized SCID pig through xenotransplantation of human hematopoietic stem cells (HSCs) would be a further demonstration of the value of such a large animal SCID model. Xenotransplantation success with HSCs into non-obese diabetic (NOD)-derived SCID mice is dependent on the ability of NOD mouse signal regulatory protein alpha (SIRPA) to bind human CD47, inducing higher phagocytic tolerance than other mouse strains. Therefore, we investigated whether porcine SIRPA binds human CD47 in the context of developing a humanized SCID pig. METHODS Peripheral blood mononuclear cells (PBMCs) were collected from SCID and non-SCID pigs. Flow cytometry was used to assess whether porcine monocytes could bind to human CD47. Porcine monocytes were isolated from PBMCs and were subjected to phagocytosis assays with pig, human, and mouse red blood cell (RBC) targets. Blocking phagocytosis assays were performed by incubating human RBCs with anti-human CD47 blocking antibody B6H12, non-blocking antibody 2D3, and nonspecific IgG1 antibody and exposing to human or porcine monocytes. RESULTS We found that porcine SIRPA binds to human CD47 in vitro by flow cytometric assays. Additionally, phagocytosis assays were performed, and we found that porcine monocytes phagocytose human and porcine RBCs at significantly lower levels than mouse RBCs. When human RBCs were preincubated with CD47 antibodies B6H12 or 2D3, phagocytosis was induced only after B6H12 incubation, indicating the lower phagocytic activity of porcine monocytes with human cells requires interaction between porcine SIRPA and human CD47. CONCLUSIONS We have shown the first evidence that porcine monocytes can bind to human CD47 and are phagocytically tolerant to human cells, suggesting that porcine SCID models have the potential to support engraftment of human HSCs.
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Affiliation(s)
| | - Joan E Cunnick
- Department of Animal Science, Iowa State University, Ames, Iowa
| | - Ellis J Powell
- Department of Animal Science, Iowa State University, Ames, Iowa.,National Animal Disease Center, Ruminant Diseases and Immunology Unit, US Department of Agriculture, Agricultural Research Service, Ames, Iowa
| | | | - Sara E Charley
- Department of Animal Science, Iowa State University, Ames, Iowa
| | - Crystal L Loving
- National Animal Disease Center, Food Safety and Enteric Pathogens Unit, US Department of Agriculture, Agricultural Research Service, Ames, Iowa
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8
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Ring NG, Herndler-Brandstetter D, Weiskopf K, Shan L, Volkmer JP, George BM, Lietzenmayer M, McKenna KM, Naik TJ, McCarty A, Zheng Y, Ring AM, Flavell RA, Weissman IL. Anti-SIRPα antibody immunotherapy enhances neutrophil and macrophage antitumor activity. Proc Natl Acad Sci U S A 2017; 114:E10578-85. [PMID: 29158380 DOI: 10.1073/pnas.1710877114] [Citation(s) in RCA: 195] [Impact Index Per Article: 27.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Cancer immunotherapy has emerged as a promising therapeutic intervention. However, complete and durable responses are only seen in a fraction of patients who have cancer. A key factor that limits therapeutic success is the infiltration of tumors by cells of the myeloid lineage. The inhibitory receptor signal regulatory protein-α (SIRPα) is a myeloid-specific immune checkpoint that engages the "don't eat me" signal CD47 expressed on tumors and normal tissues. We therefore developed the monoclonal antibody KWAR23, which binds human SIRPα with high affinity and disrupts its binding to CD47. Administered by itself, KWAR23 is inert, but given in combination with tumor-opsonizing monoclonal antibodies, KWAR23 greatly augments myeloid cell-dependent killing of a collection of hematopoietic and nonhematopoietic human tumor-derived cell lines. Following KWAR23 antibody treatment in a human SIRPA knockin mouse model, both neutrophils and macrophages infiltrate a human Burkitt's lymphoma xenograft and inhibit tumor growth, generating complete responses in the majority of treated animals. We further demonstrate that a bispecific anti-CD70/SIRPα antibody outperforms individually delivered antibodies in specific types of cancers. These studies demonstrate that SIRPα blockade induces potent antitumor activity by targeting multiple myeloid cell subsets that frequently infiltrate tumors. Thus, KWAR23 represents a promising candidate for combination therapy.
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Abstract
Background Human tyrosine-protein phosphatase non-receptor type substrate 1α (SIRPA) is a surface marker identified in cardiomyocytes differentiated from human embryonic stem cells. Our objective was to determine if circulating SIRPA levels can serve as a biomarker of cardiac injury in children undergoing open heart surgery. Results Paired pre- and post-operative serum samples from 48 pediatric patients undergoing open heart surgery and from 6 pediatric patients undergoing non-cardiac surgery (controls) were tested for SIRPA protein levels using commercially available SIRPA ELISA kits from two manufacturers. Post-operative SIRPA concentrations were significantly higher in patients after cardiac surgery compared to non-cardiac surgery when tested using SIRPA ELISA kits from both manufacturers. To verify the identity of the protein detected, recombinant human SIRPA protein (rhSIRPA) was tested on both ELISA kits. The calibrator from both ELISA kits was analyzed by Western blot as well as by Mass Spectrometry (MS). Western blot analysis of calibrators from both kits did not identity SIRPA. MS analysis of calibrators from both ELISA kits identified several inflammatory markers and albumin but no SIRPA was detected. Conclusions We conclude that commercially available ELISA kits for SIRPA give false-positive results. Verifying protein identity using robust protein characterization is critical to avoid false biomarker discovery when using commercial ELISA kits. Electronic supplementary material The online version of this article (doi:10.1186/s12858-016-0073-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Pranali Patel
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada
| | - Uros Kuzmanov
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, Canada.,Ted Rogers Centre for Heart Research, Toronto, ON, Canada
| | - Seema Mital
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada. .,Department of Pediatrics, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada. .,Ted Rogers Centre for Heart Research, Toronto, ON, Canada.
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