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Clinical and Translational Medicine Feb 2024Cluster of differentiation 47 (CD47) occupies the outer membrane of human cells, where it binds to soluble and cell surface receptors on the same and other cells,... (Review)
Review
Cluster of differentiation 47 (CD47) occupies the outer membrane of human cells, where it binds to soluble and cell surface receptors on the same and other cells, sculpting their topography and resulting in a pleiotropic receptor-multiligand interaction network. It is a focus of drug development to temper and accentuate CD47-driven immune cell liaisons, although consideration of on-target CD47 effects remain neglected. And yet, a late clinical trial of a CD47-blocking antibody was discontinued, existent trials were restrained, and development of CD47-targeting agents halted by some pharmaceutical companies. At this point, if CD47 can be exploited for clinical advantage remains to be determined. Herein an airing is made of the seemingly conflicting actions of CD47 that reflect its position as a junction connecting receptors and signalling pathways that impact numerous human cell types. Prospects of CD47 boosting and blocking are considered along with potential therapeutic implications for autoimmune diseases and cancer.
Topics: Humans; Phagocytosis; CD47 Antigen; Immunotherapy; Neoplasms; Antineoplastic Agents
PubMed: 38362603
DOI: 10.1002/ctm2.1584 -
Advanced Materials (Deerfield Beach,... Sep 2023Immunomodulation of tumor-associated macrophages (TAMs) into tumor-inhibiting M1-like phenotype is a promising but challenging strategy. Cleverly, tumor cells...
Immunomodulation of tumor-associated macrophages (TAMs) into tumor-inhibiting M1-like phenotype is a promising but challenging strategy. Cleverly, tumor cells overexpress CD47, a "don't eat me" signal that ligates with the signal regulatory protein alpha (SIRPα) on macrophages to escape phagocytosis. Thus, effective re-education of TAMs into the "eat me" type and blocking the CD47-SIRPα signaling play pivotal roles in tumor immunotherapy. Herein, it is reported that hybrid nanovesicles (hEL-RS17) derived from extracellular vesicles of M1 macrophages and decorated with RS17 peptide, an antitumor peptide that specifically binds to CD47 on tumor cells and blocks CD47-SIRPα signaling, can actively target tumor cells and remodel TAM phenotypes. Consequently, more M1-like TAMs infiltrate into tumor tissue to phagocytize more tumor cells due to CD47 blockade. By further co-encapsulating chemotherapeutic agent shikonin, photosensitizer IR820, and immunomodulator polymetformin in hEL-RS17, an enhanced antitumor effect is obtained due to the combinational treatment modality and close synergy among each component. Upon laser irradiation, the designed SPI@hEL-RS17 nanoparticles exert potent antitumor efficacy against both 4T1 breast tumor and B16F10 melanoma models, which not only suppresses primary tumor growth but also inhibits lung metastasis and prevents tumor recurrence, exhibiting great potential in boosting CD47 blockade-based antitumor immunotherapy.
Topics: Humans; CD47 Antigen; Neoplasm Recurrence, Local; Phagocytosis; Neoplasms; Immunotherapy; Extracellular Vesicles
PubMed: 37384818
DOI: 10.1002/adma.202303835 -
Methods in Molecular Biology (Clifton,... 2024One hundred years have passed since the death of Élie Metchnikoff (1845-1916). He was the first to observe the uptake of particles by cells and realized the importance... (Review)
Review
One hundred years have passed since the death of Élie Metchnikoff (1845-1916). He was the first to observe the uptake of particles by cells and realized the importance of this process, named phagocytosis, for the host response to injury and infection. He also was a strong advocate of the role of phagocytosis in cellular immunity, and with this, he gave us the basis for our modern understanding of inflammation and the innate immune response. Phagocytosis is an elegant but complex process for the ingestion and elimination of pathogens, but it is also important for the elimination of apoptotic cells and hence fundamental for tissue homeostasis. Phagocytosis can be divided into four main steps: (i) recognition of the target particle, (ii) signaling to activate the internalization machinery, (iii) phagosome formation, and (iv) phagolysosome maturation. In this chapter, we present a general view of our current knowledge on phagocytosis performed mainly by professional phagocytes through antibody and complement receptors and discuss aspects that remain incompletely understood.
Topics: Phagocytosis; Humans; Animals; Phagosomes; Phagocytes; Signal Transduction; Immunity, Innate
PubMed: 38888769
DOI: 10.1007/978-1-0716-3890-3_3 -
Immunity Sep 2023Genetic association studies have demonstrated the critical involvement of the microglial immune response in Alzheimer's disease (AD) pathogenesis. Phospholipase...
Genetic association studies have demonstrated the critical involvement of the microglial immune response in Alzheimer's disease (AD) pathogenesis. Phospholipase C-gamma-2 (PLCG2) is selectively expressed by microglia and functions in many immune receptor signaling pathways. In AD, PLCG2 is induced uniquely in plaque-associated microglia. A genetic variant of PLCG2, PLCG2, is a mild hypermorph that attenuates AD risk. Here, we identified a loss-of-function PLCG2 variant, PLCG2, that confers an increased AD risk. PLCG2 attenuated disease in an amyloidogenic murine AD model, whereas PLCG2 exacerbated the plaque burden associated with altered phagocytosis and Aβ clearance. The variants bidirectionally modulated disease pathology by inducing distinct transcriptional programs that identified microglial subpopulations associated with protective or detrimental phenotypes. These findings identify PLCG2 as a potential AD risk variant and demonstrate that PLCG2 variants can differentially orchestrate microglial responses in AD pathogenesis that can be therapeutically targeted.
Topics: Animals; Mice; Alzheimer Disease; Genetic Association Studies; Microglia; Phagocytosis; Phenotype; Plaque, Amyloid; Phospholipase C gamma
PubMed: 37659412
DOI: 10.1016/j.immuni.2023.08.008 -
Seminars in Immunology Nov 2023Neutrophils are among the most abundant immune cells, representing about 50%- 70% of all circulating leukocytes in humans. Neutrophils rapidly infiltrate inflamed... (Review)
Review
Neutrophils are among the most abundant immune cells, representing about 50%- 70% of all circulating leukocytes in humans. Neutrophils rapidly infiltrate inflamed tissues and play an essential role in host defense against infections. They exert microbicidal activity through a variety of specialized effector mechanisms, including phagocytosis, production of reactive oxygen species, degranulation and release of secretory vesicles containing broad-spectrum antimicrobial factors. In addition to their homeostatic turnover by apoptosis, recent studies have revealed the mechanisms by which neutrophils undergo various forms of regulated cell death. In this review, we will discuss the different modes of regulated cell death that have been described in neutrophils, with a particular emphasis on the current understanding of neutrophil pyroptosis and its role in infections and autoinflammation.
Topics: Humans; Neutrophils; Pyroptosis; Phagocytosis; Apoptosis
PubMed: 37939552
DOI: 10.1016/j.smim.2023.101849 -
Journal of Translational Medicine Sep 2023The chimeric antigen receptor (CAR)-T therapy has a limited therapeutic effect on solid tumors owing to the limited CAR-T cell infiltration into solid tumors and the...
BACKGROUND
The chimeric antigen receptor (CAR)-T therapy has a limited therapeutic effect on solid tumors owing to the limited CAR-T cell infiltration into solid tumors and the inactivation of CAR-T cells by the immunosuppressive tumor microenvironment. Macrophage is an important component of the innate and adaptive immunity, and its unique phagocytic function has been explored to construct CAR macrophages (CAR-Ms) against solid tumors. This study aimed to investigate the therapeutic application of CAR-Ms in ovarian cancer.
METHODS
In this study, we constructed novel CAR structures, which consisted of humanized anti-HER2 or CD47 scFv, CD8 hinge region and transmembrane domains, as well as the 4-1BB and CD3ζ intracellular domains. We examined the phagocytosis of HER2 CAR-M and CD47 CAR-M on ovarian cancer cells and the promotion of adaptive immunity. Two syngeneic tumor models were used to estimate the in vivo antitumor activity of HER2 CAR-M and CD47 CAR-M.
RESULTS
We constructed CAR-Ms targeting HER2 and CD47 and verified their phagocytic ability to ovarian cancer cells in vivo and in vitro. The constructed CAR-Ms showed antigen-specific phagocytosis of ovarian cancer cells in vitro and could activate CD8 cytotoxic T lymphocyte (CTL) to secrete various anti-tumor factors. For the in vivo model, mice with human-like immune systems were used. We found that CAR-Ms enhanced CD8 T cell activation, affected tumor-associated macrophage (TAM) phenotype, and led to tumor regression.
CONCLUSIONS
We demonstrated the inhibition effect of our constructed novel HER2 CAR-M and CD47 CAR-M on target antigen-positive ovarian cancer in vitro and in vivo, and preliminarily verified that this inhibitory effect is due to phagocytosis, promotion of adaptive immunity and effect on tumor microenvironment.
Topics: Humans; Female; Animals; Mice; CD47 Antigen; Ovarian Neoplasms; Macrophages; Phagocytosis; Tumor Microenvironment
PubMed: 37740183
DOI: 10.1186/s12967-023-04479-8 -
Science (New York, N.Y.) Apr 2024Macrophages are functionally heterogeneous cells essential for apoptotic cell clearance. Apoptotic cells are defined by homogeneous characteristics, ignoring their...
Macrophages are functionally heterogeneous cells essential for apoptotic cell clearance. Apoptotic cells are defined by homogeneous characteristics, ignoring their original cell lineage identity. We found that in an interleukin-4 (IL-4)-enriched environment, the sensing of apoptotic neutrophils by macrophages triggered their tissue remodeling signature. Engulfment of apoptotic hepatocytes promoted a tolerogenic phenotype, whereas phagocytosis of T cells had little effect on IL-4-induced gene expression. In a mouse model of parasite-induced pathology, the transfer of macrophages conditioned with IL-4 and apoptotic neutrophils promoted parasitic egg clearance. Knockout of phagocytic receptors required for the uptake of apoptotic neutrophils and partially T cells, but not hepatocytes, exacerbated helminth infection. These findings suggest that the identity of apoptotic cells may contribute to the development of distinct IL-4-driven immune programs in macrophages.
Topics: Animals; Mice; Apoptosis; Hepatocytes; Interleukin-4; Macrophages; Mice, Knockout; Neutrophils; Phagocytosis; Schistosomiasis mansoni; Disease Models, Animal
PubMed: 38574142
DOI: 10.1126/science.abo7027 -
Nature Immunology Dec 2023Cancer cells often overexpress CD47, which triggers the inhibitory receptor SIRPα expressed on macrophages, to elude phagocytosis and antitumor immunity....
Cancer cells often overexpress CD47, which triggers the inhibitory receptor SIRPα expressed on macrophages, to elude phagocytosis and antitumor immunity. Pharmacological blockade of CD47 or SIRPα is showing promise as anticancer therapy, although CD47 blockade has been associated with hematological toxicities that may reflect its broad expression pattern on normal cells. Here we found that, in addition to triggering SIRPα, CD47 suppressed phagocytosis by a SIRPα-independent mechanism. This mechanism prevented phagocytosis initiated by the pro-phagocytic ligand, SLAMF7, on tumor cells, due to a cis interaction between CD47 and SLAMF7. The CD47-SLAMF7 interaction was disrupted by CD47 blockade and by a first-in-class agonist SLAMF7 antibody, but not by SIRPα blockade, thereby promoting antitumor immunity. Hence, CD47 suppresses phagocytosis not only by engaging SIRPα, but also by masking cell-intrinsic pro-phagocytic ligands on tumor cells and knowledge of this mechanism may influence the decision between CD47 blockade or SIRPα blockade for therapeutic purposes.
Topics: Humans; Antigens, Differentiation; CD47 Antigen; Ligands; Macrophages; Neoplasms; Phagocytosis; Tumor Escape; Animals; Mice
PubMed: 37945822
DOI: 10.1038/s41590-023-01671-2 -
Cancer Immunology, Immunotherapy : CII Sep 2023The use of treatments, such as programmed death protein 1 (PD1) or cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) antibodies, that loosen the natural checks upon... (Review)
Review
The use of treatments, such as programmed death protein 1 (PD1) or cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) antibodies, that loosen the natural checks upon immune cell activity to enhance cancer killing have shifted clinical practice and outcomes for the better. Accordingly, the number of antibodies and engineered proteins that interact with the ligand-receptor components of immune checkpoints continue to increase along with their use. It is tempting to view these molecular pathways simply from an immune inhibitory perspective. But this should be resisted. Checkpoint molecules can have other cardinal functions relevant to the development and use of blocking moieties. Cell receptor CD47 is an example of this. CD47 is found on the surface of all human cells. Within the checkpoint paradigm, non-immune cell CD47 signals through immune cell surface signal regulatory protein alpha (SIRPα) to limit the activity of the latter, the so-called trans signal. Even so, CD47 interacts with other cell surface and soluble molecules to regulate biogas and redox signaling, mitochondria and metabolism, self-renewal factors and multipotency, and blood flow. Further, the pedigree of checkpoint CD47 is more intricate than supposed. High-affinity interaction with soluble thrombospondin-1 (TSP1) and low-affinity interaction with same-cell SIRPα, the so-called cis signal, and non-SIRPα ectodomains on the cell membrane suggests that multiple immune checkpoints converge at and through CD47. Appreciation of this may provide latitude for pathway-specific targeting and intelligent therapeutic effect.
Topics: Humans; CD47 Antigen; Antigens, Differentiation; Receptors, Immunologic; Neoplasms; Antibodies; Carrier Proteins; Phagocytosis
PubMed: 37217603
DOI: 10.1007/s00262-023-03465-9 -
Cell Reports Jul 2023Tissue-resident macrophages (TRMs) and dendritic cells (DCs) are highly heterogeneous and essential for immunity, tissue regeneration, and homeostasis maintenance. Here,...
Tissue-resident macrophages (TRMs) and dendritic cells (DCs) are highly heterogeneous and essential for immunity, tissue regeneration, and homeostasis maintenance. Here, we comprehensively profile the heterogeneity of TRMs and DCs across adult zebrafish organs via single-cell RNA sequencing. We identify two macrophage subsets: pro-inflammatory macrophages with potent phagocytosis signatures and pro-remodeling macrophages with tissue regeneration signatures in barrier tissues, liver, and heart. In parallel, one conventional dendritic cell (cDC) population with prominent antigen presentation capacity and plasmacytoid dendritic cells (pDCs) featured by anti-virus properties are also observed in these organs. Remarkably, in addition to a single macrophage/microglia population with potent phagocytosis capacity, a pDC population and two distinct cDC populations are identified in the brain. Finally, we generate specific reporter lines for in vivo tracking of macrophage and DC subsets. Our study depicts the landscape of TRMs and DCs and creates valuable tools for in-depth study of these cells in zebrafish.
Topics: Animals; Zebrafish; Macrophages; Gene Expression Profiling; Dendritic Cells; Phagocytosis; Transcriptome
PubMed: 37453064
DOI: 10.1016/j.celrep.2023.112793