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Updated: Aug 21, 2026
Cell-based Assay to Study Antibody-mediated Tau Clearance by Microglia
Published on: November 9, 2018
Ms4a4a loss reprograms amyloid-associated microglia and limits dense-core plaque-associated tau spreading
Introduction:
Microglia regulate amyloid plaque-associated microenvironments that contribute to downstream tau pathology in Alzheimer's disease (AD). Variants within the MS4A locus are strongly associated with AD risk and resilience and are linked to microglial biology; however, the functional role of MS4A4A in plaque-associated tau pathology remains poorly understood.
Methods:
Single-nucleus RNA sequencing (snRNA-seq) was performed on hippocampi from non-transgenic, Ms4a4a knockout (4A-KO), 5xFAD, and 5xFAD 4A-KO mice at 6 months of age. To assess plaque-associated tau pathology, AD-derived tau aggregates were injected into the hippocampus of 5xFAD and 5xFAD 4A-KO mice at 6 months, and histological analyses were performed 3 months later.
Results:
Amyloid pathology was the dominant driver of microglial state transitions, while Ms4a4a loss selectively remodeled activated microglial transcriptional programs enriched for interferon, lysosomal, autophagic, and proteostatic pathways. Activated microglia from 5xFAD 4A-KO mice exhibited altered expression of genes linked to immune signaling and protein handling. Following AD-tau inoculation, Ms4a4a loss did not significantly alter overall phospho-tau burden but selectively reduced dense-core plaque-associated neuritic plaque tau (NP-tau), particularly in the contralateral hemisphere. This phenotype was strongest surrounding X-34-positive fibrillar plaques and occurred without major changes in plaque-associated microgliosis.
Discussion:
These findings identify Ms4a4a as a regulator of plaque-associated microglial programs linked to NP-tau accumulation in the amyloid-bearing brain. More broadly, this work supports a model in which AD resilience-associated microglial pathways selectively shape plaque-associated microenvironments that promote downstream tau pathology.
Insights
The gene MS4A4A influences how microglia respond to amyloid plaques, potentially reducing specific tau pathology in Alzheimer's disease (AD) brains. This suggests microglial pathways may offer resilience against AD progression.
Area of Science:
- Neuroscience
- Immunology
- Genetics
Background:
- Microglia play a key role in Alzheimer's disease (AD) by modulating amyloid plaque environments, which influences tau pathology.
- Genetic variants in the MS4A locus are linked to AD risk and microglial function, but the specific role of MS4A4A in tau pathology is unclear.
Purpose of the Study:
- To investigate the functional role of MS4A4A in regulating microglial responses to amyloid pathology and its impact on tau seeding and propagation in a mouse model of AD.
- To determine how MS4A4A deficiency affects microglial transcriptional programs in the context of amyloidosis and tau pathology.
Main Methods:
- Single-nucleus RNA sequencing (snRNA-seq) was employed on mouse hippocampi (non-transgenic, Ms4a4a knockout, 5xFAD, and 5xFAD Ms4a4a knockout).
- AD-derived tau aggregates were stereotactically injected into the hippocampus of 5xFAD and 5xFAD Ms4a4a knockout mice to assess tau pathology progression.
- Histological analyses were conducted 3 months post-tau inoculation to evaluate plaque-associated tau burden and microglial responses.
Main Results:
- Amyloid pathology was the primary driver of microglial state changes.
- Loss of Ms4a4a selectively altered microglial transcriptional programs, particularly those involved in interferon, lysosomal, autophagic, and proteostatic pathways.
- While overall phospho-tau levels were unchanged, Ms4a4a deficiency significantly reduced neuritic plaque tau (NP-tau) burden, especially in the contralateral hemisphere, around dense-core plaques, without altering plaque-associated microgliosis.
Conclusions:
- MS4A4A acts as a regulator of microglial programs associated with amyloid plaques, influencing NP-tau accumulation in the amyloid-laden brain.
- These findings support a model where microglial pathways, potentially conferring AD resilience, can selectively modify plaque microenvironments to impact downstream tau pathology.
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