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Updated: Sep 29, 2025
Mesenchymal Stem Cell Regulation of Macrophage Phagocytosis; Quantitation and Imaging
Published on: July 16, 2021
Suppressing or Enhancing Macrophage Engulfment through the Use of CD47 and Related Peptides
Abstract:
Foreign particles and microbes are rapidly cleared by macrophages in vivo, although many key aspects of uptake mechanisms remain unclear. "Self" cells express CD47 which functions as an anti-phagocytic ligand for SIRPα on macrophages, particularly when pro-phagocytic ligands such as antibodies are displayed in parallel. Here, we review CD47 and related "Self" peptides as modulators of macrophage uptake. Nanoparticles conjugated with either CD47 or peptides derived from its SIRPα binding site can suppress phagocytic uptake by macrophages in vitro and in vivo, with similar findings for CD47-displaying viruses. Drugs, dyes, and genes as payloads thus show increased delivery to targeted cells. On the other hand, CD47 expression by cancer cells enables such cells to evade macrophages and immune surveillance. This has motivated development of soluble antagonists to CD47-SIRPα, ranging from blocking antibodies in the clinic to synthetic peptides in preclinical models. CD47 and peptides are thus emerging as dual-use phagocytosis modulators against diseases.
Insights
Macrophages clear foreign particles using CD47, a "Self" signal. Modulating CD47 and related peptides offers new strategies for targeted drug delivery and cancer immunotherapy by controlling phagocytosis.
Area of Science:
- Immunology
- Cell Biology
- Biotechnology
Background:
- Macrophages rapidly clear foreign particles and microbes in vivo.
- CD47 acts as an anti-phagocytic "Self" signal on cells, interacting with SIRPα on macrophages.
- The precise mechanisms of phagocytic uptake are not fully understood.
Purpose of the Study:
- To review CD47 and related "Self" peptides as modulators of macrophage uptake.
- To explore the therapeutic potential of targeting the CD47-SIRPα pathway.
Main Methods:
- Review of existing literature on CD47, SIRPα, and phagocytosis.
- Analysis of studies involving nanoparticles, viruses, and peptides conjugated with CD47 or its binding site.
- Examination of clinical and preclinical data on CD47-SIRPα antagonists.
Main Results:
- Nanoparticles and viruses displaying CD47 or SIRPα-binding peptides suppress macrophage phagocytosis in vitro and in vivo.
- This modulation enhances the delivery of payloads like drugs, dyes, and genes to targeted cells.
- Cancer cells expressing CD47 evade macrophage surveillance, contributing to immune evasion.
Conclusions:
- CD47 and derived peptides are emerging as dual-use phagocytosis modulators.
- Targeting the CD47-SIRPα axis presents therapeutic opportunities for both enhancing drug delivery and combating cancer.
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