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Updated: May 1, 2026
Cell-based Assay to Study Antibody-mediated Tau Clearance by Microglia
Published on: November 9, 2018
Activated scavenger receptor A promotes glial internalization of aβ
He Zhang1, Ya-jing Su2, Wei-wei Zhou3
1National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, China; Tsinghua University School of Medicine, Haidian District, Beijing, China.
Abstract:
Beta-amyloid (Aβ) aggregates have a pivotal role in pathological processing of Alzheimer's disease (AD). The clearance of Aβ monomer or aggregates is a causal strategy for AD treatment. Microglia and astrocytes are the main macrophages that exert critical neuroprotective roles in the brain. They may effectively clear the toxic accumulation of Aβ at the initial stage of AD, however, their functions are attenuated because of glial overactivation. In this study, we first showed that heptapeptide XD4 activates the class A scavenger receptor (SR-A) on the glia by increasing the binding of Aβ to SR-A, thereby promoting glial phagocytosis of Aβ oligomer in microglia and astrocytes and triggering intracellular mitogen-activated protein kinase (MAPK) signaling cascades. Moreover, XD4 enhances the internalization of Aβ monomers to microglia and astrocytes through macropinocytosis or SR-A-mediated phagocytosis. Furthermore, XD4 significantly inhibits Aβ oligomer-induced cytotoxicity to glial cells and decreases the production of proinflammatory cytokines, such as TNF-α and IL-1β, in vitro and in vivo. Our findings may provide a novel strategy for AD treatment by activating SR-A.
Insights
Heptapeptide XD4 enhances glial cells
Area of Science:
- Neuroscience
- Immunology
Background:
- Beta-amyloid (Aβ) aggregates are central to Alzheimer's disease (AD) pathology.
- Glial cells, including microglia and astrocytes, clear Aβ but can become overactivated, impairing function.
- Effective Aβ clearance is a key therapeutic strategy for AD.
Purpose of the Study:
- To investigate the effect of heptapeptide XD4 on Aβ clearance by glial cells.
- To explore the underlying mechanisms of XD4-mediated Aβ clearance.
Main Methods:
- Assessed Aβ binding to scavenger receptor A (SR-A) on microglia and astrocytes.
- Measured Aβ phagocytosis and internalization promoted by XD4.
- Analyzed mitogen-activated protein kinase (MAPK) signaling activation.
- Evaluated XD4's effect on glial cell cytotoxicity and pro-inflammatory cytokine production (TNF-α, IL-1β) in vitro and in vivo.
Main Results:
- XD4 activates SR-A on glia, enhancing Aβ binding and promoting phagocytosis of Aβ oligomers.
- XD4 facilitates Aβ monomer internalization via macropinocytosis and SR-A-mediated phagocytosis.
- XD4 reduces Aβ oligomer-induced glial cytotoxicity and pro-inflammatory cytokine release.
Conclusions:
- Heptapeptide XD4 shows therapeutic potential for Alzheimer's disease by enhancing glial Aβ clearance.
- Activating SR-A with XD4 represents a novel strategy for AD treatment.
