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Updated: Jul 12, 2026
An Engulfment Assay: A Protocol to Assess Interactions Between CNS Phagocytes and Neurons
Published on: June 8, 2014
FcγR- and CD9-dependent synapse-engulfing microglia in the thalamus drive cognitive impairment following cortical
Ken Matoba1, Takahiro Kochi1,2, Oluwaseun Fatoba1
1Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham Heersink School of Medicine, Birmingham, AL, USA.
Abstract:
Chronic neuroinflammation gives rise to diverse microglial states across the brain, yet how region-specific microglial remodeling contributes to cognitive dysfunction remains unclear. Here we report that synapse-engulfing microglia in the thalamus drive cognitive impairment after cortical brain damage in mice, primarily studied in females. Region-specific manipulations of microglia during the chronic phase show that reactive microglial changes in the thalamus, but not in the hippocampus, impair recognition memory. Single-cell RNA sequencing reveals an enrichment of synapse-engulfing CD9hi microglia in the thalamus. Antibody-based CD9 blockade in the thalamus, as well as microglia-selective CD9 disruption, rescues thalamic synaptic loss, restores neuronal activity, and improves recognition memory. Further analysis shows that the blood-brain barrier disruption and subsequent γ-immunoglobulin (IgG) extravasation facilitate the generation of CD9hi microglia in an Fcγ receptor III-dependent manner. These findings demonstrate that the induction of synapse-engulfing CD9hi microglia in the thalamus by IgG/FcγRIII signaling drives recognition memory deficits following cortical damage.
Insights
Synapse-engulfing microglia in the thalamus, not the hippocampus, cause memory loss after brain damage. Blocking CD9 on these microglia restores memory, revealing a new therapeutic target for cognitive dysfunction.
Area of Science:
- Neuroscience
- Immunology
Background:
- Chronic neuroinflammation involves diverse microglial states.
- The role of region-specific microglial changes in cognitive dysfunction is not fully understood.
Purpose of the Study:
- To investigate how region-specific microglial remodeling contributes to cognitive dysfunction after cortical brain damage.
- To identify the mechanisms driving microglial changes and their impact on memory.
Main Methods:
- Single-cell RNA sequencing to identify microglial subtypes.
- Region-specific microglial manipulation in mice.
- Antibody-based CD9 blockade and microglia-selective CD9 disruption.
- Analysis of synaptic loss, neuronal activity, and recognition memory.
Main Results:
- Synapse-engulfing CD9hi microglia are enriched in the thalamus and drive cognitive impairment.
- Thalamic microglial changes, but not hippocampal ones, impair recognition memory.
- CD9 blockade or disruption in the thalamus rescues synaptic loss and improves memory.
- Blood-brain barrier disruption and IgG extravasation induce CD9hi microglia via FcγRIII signaling.
Conclusions:
- Thalamic synapse-engulfing microglia mediate cognitive deficits post-cortical damage.
- IgG/FcγRIII signaling drives the generation of these detrimental microglia.
- Targeting CD9 in the thalamus offers a potential therapeutic strategy for memory recovery.
