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Updated: Dec 20, 2025
Screening Bioactive Nanoparticles in Phagocytic Immune Cells for Inhibitors of Toll-like Receptor Signaling
Published on: July 26, 2017
Diminution of Phagocytosed Micro/Nanoparticles by Tethering with Immunoregulatory CD200 Protein
1Department of Biological Engineering, University of Idaho, Moscow, ID, 83844, USA.
Insights
CD200-coated nanoparticles reduce macrophage phagocytosis and inflammatory markers like TNF-α. This suggests CD200’s potential for modulating immune responses and treating inflammation.
Area of Science:
- Immunology
- Biomaterials Science
Background:
- CD200 is an anti-inflammatory glycoprotein that interacts with CD200R on myeloid cells.
- This interaction is known to reduce macrophage activation and chronic inflammation.
Purpose of the Study:
- To functionalize micro/nanoparticles with CD200 for immunomodulatory applications.
- To investigate the effect of CD200-modified particles on macrophage behavior.
Main Methods:
- Engineered a CD200-streptavidin fusion protein.
- Immobilized the fusion protein onto biotinylated polystyrene particles (0.15–2 µm).
- Assessed phagocytosis, Toll-like receptor 4 (TLR4) expression, and TNF-α secretion in THP-1 macrophages treated with modified particles.
Main Results:
- CD200-coated micro/nanoparticles significantly decreased macrophage phagocytosis.
- This reduction in phagocytosis correlated with downregulated TLR4 expression.
- Macrophages treated with CD200 particles showed reduced secretion of tumor necrosis factor-α (TNF-α).
Conclusions:
- CD200 surface modification of micro/nanoparticles effectively suppresses macrophage phagocytic activity.
- The mechanism involves downregulation of TLR4 expression and reduced pro-inflammatory cytokine secretion.
- CD200-functionalized materials hold promise for developing novel anti-inflammatory therapies.
Abstract:
CD200 is known as an anti-inflammatory transmembrane glycoprotein in the immunoglobulin superfamily. CD200 interacts with its receptor CD200R which is highly expressed on myeloid cells such as macrophages and neutrophils. CD200-CD200R interaction has known to reduce macrophage activation and chronic inflammation. To harness the immunomodulatory property of CD200 for surface modification, CD200-streptavidin fusion protein was expressed from bacteria transformed with pET20b plasmid encoded with CD200 extracellular domain and core streptavidin. The purified CD200-SA protein was bound to biotin-coated fluorescent polystyrene particles of various sizes ranging from 0.15 to 2 µm. THP-1 macrophages were cultivated with CD200-modified micro/nanoparticles in comparison with controls. Our results showed that both nano- and micro-sized particles decorated with CD200 decreased phagocytosis activities of THP-1 macrophages. Such diminution of phagocytosis was examined to be associated with downregulation of Toll-like receptor 4 (TLR4) expression on the surface of macrophages. Moreover, THP-1 macrophages treated with CD200-coated particles decreased the secretion of tumor necrosis factor-α (TNF-α).
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