Cited by 112Neuroinflammation and Neurodegeneration MechanismsPhagocytosis and Immune RegulationGlycosylation and Glycoproteins Research

Activated Microglia Desialylate and Phagocytose Cells via Neuraminidase, Galectin-3, and Mer Tyrosine Kinase

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Nomura, Koji, Vilalta, Anna, Allendorf, David H, Hornik, Tamara C, Brown, Guy C·2017·The Journal of Immunology

Abstract

Activated microglia can phagocytose dying, stressed, or excess neurons and synapses via the phagocytic receptor Mer tyrosine kinase (MerTK). Galectin-3 (Gal-3) can cross-link surface glycoproteins by binding galactose residues that are normally hidden below terminal sialic acid residues. Gal-3 was recently reported to opsonize cells via activating MerTK. We found that LPS-activated BV-2 microglia rapidly released Gal-3, which was blocked by calcineurin inhibitors. Gal-3 bound to MerTK on microglia and to stressed PC12 (neuron-like) cells, and it increased microglial phagocytosis of PC12 cells or primary neurons, which was blocked by inhibition of MerTK. LPS-activated microglia exhibited a sialidase activity that desialylated PC12 cells and could be inhibited by Tamiflu, a neuraminidase (sialidase) inhibitor. Sialidase treatment of PC12 cells enabled Gal-3 to bind and opsonize the live cells for phagocytosis by microglia. LPS-induced microglial phagocytosis of PC12 was prevented by small interfering RNA knockdown of Gal-3 in microglia, lactose inhibition of Gal-3 binding, inhibition of neuraminidase with Tamiflu, or inhibition of MerTK by UNC569. LPS-induced phagocytosis of primary neurons by primary microglia was also blocked by inhibition of MerTK. We conclude that activated microglia release Gal-3 and a neuraminidase that desialylates microglial and PC12 surfaces, enabling Gal-3 binding to PC12 cells and their phagocytosis via MerTK. Thus, Gal-3 acts as an opsonin of desialylated surfaces, and inflammatory loss of neurons or synapses may potentially be blocked by inhibiting neuraminidases, Gal-3, or MerTK.

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Crossref · 10.4049/jimmunol.1502532

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  • The absence of ramified microglial cells may stem from BV-2 cells being a transformed microglia cell line with different morphology compared to microglia directly isolated from animals.

    “This may stem from the BV-2 cells, a transformed microglia cell line with differed morphology compared to microglia directly isolated from the animals,48 which was reported previously.51–53”

    From Acoustofluidic assembly of 3D neurospheroids to model Alzheimer's disease (2020) · cites this paper as [53]

    The Materials and methods section (page unavailable) identifies BV-2 as a murine microglial cell line, and the References list its immortalization. The paper does not say that BV-2 cells differ morphologically from microglia isolated from animals or that this explains an absence of ramified cells. (LLM, conf=0.85)

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  1. [32]Stamatos NM Liang F Nan X Landry K Cross AS Wang LX Pshezhetsky AV Differential expression of endogenous sialidases of human monocytes during cellular differentiation into macrophages FEBS J 2005 272 2545 2556 15885103

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Authors
Nomura, K., Vilalta, A., Allendorf, D. H., Hornik, T. C., & Brown, G. C.
Affiliations
University of Cambridge (GB)
Corresponding author
Brown, Guy C
Venue
The Journal of Immunology
Published
2017-06
Volume
198
Issue
12
Pages
4792-4801
ISSN
  • 0022-1767 (ISSN-L)
  • 1550-6606
OpenAlex
W2612664982
Cited by
111
References
48
Citations by year
2026: 9 · 2025: 10 · 2024: 14 · 2023: 7 · 2022: 17 · 2021: 17 · 2020: 15 · 2019: 9 · 2018: 7 · 2017: 4
FWCI
4.77
Type
journal article
Language
en
Open access
Locations
  • The Journal of Immunology (publishedVersion, cc-by)
  • Europe PMC (PubMed Central) (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • ENLIGHTEN (Jurnal Bimbingan dan Konseling Islam) (acceptedVersion)
  • Apollo (University of Cambridge) (submittedVersion, cc-by)
  • Apollo (cc-by)
Funders
Medical Research Council (MR/L010593/1)
Topics
  • Life Sciences › Neuroscience › Neurology › Neuroinflammation and Neurodegeneration Mechanisms
  • Life Sciences › Immunology and Microbiology › Immunology › Phagocytosis and Immune Regulation
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Glycosylation and Glycoproteins Research
Keywords
microglia, phagocytosis, galectin-3, MERTK, neuraminidase, sialic acid, desialylation, opsonization, lipopolysaccharide stimulation, PC12 cells, neurons, calcineurin, neuraminidase inhibitors, synaptic loss, neuroinflammation
MeSH terms
c-Mer Tyrosine Kinase, Animals, Galactose, Lipopolysaccharides, Macrophages, Neuraminidase, Neurons, Opsonin Proteins, Phagocytosis, Proto-Oncogene Proteins, Pyrazoles, Pyrimidines, PC12 Cells, Microglia, Receptor Protein-Tyrosine Kinases, Galectin 3, Rats, Oseltamivir

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