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Updated: Jun 24, 2026
Quantitative 3D In Silico Modeling (q3DISM) of Cerebral Amyloid-beta Phagocytosis in Rodent Models of Alzheimer's Disease
Published on: December 26, 2016
Lilrb4a Suppression Reprograms Microglia to Mitigate APOE4-Associated Amyloid Plaques and Cerebral Amyloid Angiopathy
Changxu Nie1,2, Ruixi Yang1, Xiaotong Wang1
1Department of Psychiatry, The First Affiliated Hospital of Chongqing Medical University, Department of Neurobiology, School of Basic Medical Sciences, Key Laboratory of Major Brain Disease and Aging Research (Ministry of Education), Chongqing Medical University, Chongqing, China.
Abstract:
The mouse gene Lilrb4a, an ortholog of human leukocyte immunoglobulin-like receptor B4 (LILRB4), is markedly upregulated in microglia in Alzheimer's disease models and has been implicated in Apolipoprotein E (APOE)-related signaling. However, its contribution to amyloid pathology under an APOE4 background remains unclear. Here, 5xFAD mice carrying human APOE4 were used to assess the impact of Lilrb4a reduction by genetic deletion or antisense oligonucleotide treatment. Both approaches significantly reduced cortical amyloid plaque burden and APOE4-associated cerebral amyloid angiopathy without altering amyloid-β (Aβ) production. Bulk RNA sequencing identified enrichment of peroxisome proliferator-activated receptor (PPAR)-related and broader metabolic pathways in Lilrb4a-deficient mice. Consistently, biochemical analyses showed reduced p-SHP-2, NF-κB-p65, and p-STAT1, increased p-STAT3, and induction of anti-inflammatory and clearance-associated effectors, including Arg-1, TGF-β, and Cyp2e1. In primary microglia, pharmacological interrogation supported a functional contribution of PPAR-γ signaling to the enhanced Aβ uptake and degradation associated with Lilrb4a suppression, whereas PPAR-γ agonism recapitulated key pro-clearance phenotypes in vitro and attenuated amyloid pathology in vivo. Together, these data support Lilrb4a as an APOE4-associated microglial checkpoint candidate linked to impaired amyloid clearance and identify a PPAR-linked pro-clearance program as a potential downstream component of this response.
Insights
The mouse gene Lilrb4a is upregulated in Alzheimer's disease and linked to APOE4. Reducing Lilrb4a in mice decreased amyloid plaques and improved clearance via PPAR-gamma signaling.
Area of Science:
- Neuroscience
- Immunology
- Genetics
Background:
- Leukocyte immunoglobulin-like receptor B4 (LILRB4) is upregulated in microglia in Alzheimer's disease (AD) models.
- Lilrb4a, the mouse ortholog of LILRB4, is implicated in Apolipoprotein E (APOE)-related signaling in AD.
- The specific role of Lilrb4a in amyloid pathology, particularly under an APOE4 background, is not well understood.
Purpose of the Study:
- To investigate the impact of Lilrb4a reduction on amyloid pathology in a mouse model of Alzheimer's disease with APOE4.
- To elucidate the molecular mechanisms underlying Lilrb4a's role in microglial function and amyloid clearance.
Main Methods:
- Utilized 5xFAD mice carrying human APOE4, employing genetic deletion and antisense oligonucleotide treatment to reduce Lilrb4a expression.
- Performed bulk RNA sequencing and biochemical analyses to identify molecular pathways affected by Lilrb4a deficiency.
- Conducted in vitro studies using primary microglia and in vivo experiments with pharmacological interventions.
Main Results:
- Reduction of Lilrb4a significantly decreased cortical amyloid plaque burden and APOE4-associated cerebral amyloid angiopathy.
- No alteration in amyloid-beta (Aβ) production was observed, suggesting a role in clearance rather than production.
- Identified enrichment of peroxisome proliferator-activated receptor (PPAR)-related and metabolic pathways, with modulation of key signaling molecules (e.g., SHP-2, NF-κB, STATs) and induction of anti-inflammatory/clearance effectors (Arg-1, TGF-β, Cyp2e1).
- Demonstrated that PPAR-γ signaling mediates enhanced Aβ uptake and degradation in microglia upon Lilrb4a suppression.
Conclusions:
- Lilrb4a acts as an APOE4-associated microglial checkpoint contributing to impaired amyloid clearance in Alzheimer's disease.
- PPAR-γ signaling is a crucial downstream component of the Lilrb4a-mediated pro-clearance program.
- Targeting Lilrb4a or activating PPAR-γ signaling presents a potential therapeutic strategy for Alzheimer's disease.
