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Updated: Apr 30, 2026
Isolation of Cortical Microglia with Preserved Immunophenotype and Functionality From Murine Neonates
Published on: January 30, 2014
Suppression of Alzheimer-associated inflammation by microglial prostaglandin-E2 EP4 receptor signaling
Nathaniel S Woodling1, Qian Wang, Prachi G Priyam
1Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California 94305, Neurosciences Graduate Program, Stanford University, Stanford, California 94305, and Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232.
Abstract:
A persistent and nonresolving inflammatory response to accumulating Aβ peptide species is a cardinal feature in the development of Alzheimer's disease (AD). In response to accumulating Aβ peptide species, microglia, the innate immune cells of the brain, generate a toxic inflammatory response that accelerates synaptic and neuronal injury. Many proinflammatory signaling pathways are linked to progression of neurodegeneration. However, endogenous anti-inflammatory pathways capable of suppressing Aβ-induced inflammation represent a relatively unexplored area. Here we report that signaling through the prostaglandin-E2 (PGE2) EP4 receptor potently suppresses microglial inflammatory responses to Aβ42 peptides. In cultured microglial cells, EP4 stimulation attenuated levels of Aβ42-induced inflammatory factors and potentiated phagocytosis of Aβ42. Microarray analysis demonstrated that EP4 stimulation broadly opposed Aβ42-driven gene expression changes in microglia, with enrichment for targets of IRF1, IRF7, and NF-κB transcription factors. In vivo, conditional deletion of microglial EP4 in APPSwe-PS1ΔE9 (APP-PS1) mice conversely increased inflammatory gene expression, oxidative protein modification, and Aβ deposition in brain at early stages of pathology, but not at later stages, suggesting an early anti-inflammatory function of microglial EP4 signaling in the APP-PS1 model. Finally, EP4 receptor levels decreased significantly in human cortex with progression from normal to AD states, suggesting that early loss of this beneficial signaling system in preclinical AD development may contribute to subsequent progression of pathology.
Insights
The prostaglandin-E2 (PGE2) EP4 receptor signaling suppresses harmful microglial inflammation in Alzheimer's disease (AD). Loss of EP4 function exacerbates early AD pathology, indicating its protective role.
Area of Science:
- Neuroscience
- Immunology
- Pharmacology
Background:
- Alzheimer's disease (AD) is characterized by persistent neuroinflammation driven by amyloid-beta (Aβ) peptides.
- Microglia, the brain's innate immune cells, contribute to neurodegeneration through toxic inflammatory responses to Aβ.
- Endogenous anti-inflammatory pathways that counteract Aβ-induced inflammation are not well understood.
Purpose of the Study:
- To investigate the role of prostaglandin-E2 (PGE2) EP4 receptor signaling in modulating microglial inflammatory responses to Aβ.
- To determine the therapeutic potential of EP4 receptor activation in Alzheimer's disease models.
Main Methods:
- In vitro studies using cultured microglial cells exposed to Aβ42 peptides.
- Microarray analysis to assess gene expression changes in microglia.
- In vivo studies using APPSwe-PS1ΔE9 (APP-PS1) transgenic mice with conditional deletion of microglial EP4.
- Analysis of human cortical tissue from normal and AD individuals.
Main Results:
- EP4 receptor stimulation in microglia attenuated Aβ42-induced inflammatory factors and enhanced Aβ42 phagocytosis.
- EP4 stimulation opposed Aβ42-driven gene expression changes, including targets of IRF1, IRF7, and NF-κB.
- Conditional deletion of microglial EP4 in APP-PS1 mice increased early-stage neuroinflammation, oxidative damage, and Aβ deposition.
- EP4 receptor levels were significantly reduced in human AD cortex compared to normal controls.
Conclusions:
- Signaling through the PGE2 EP4 receptor acts as a potent endogenous anti-inflammatory pathway in microglia, suppressing detrimental responses to Aβ.
- Early loss of microglial EP4 signaling may contribute to the progression of Alzheimer's disease pathology.
- Targeting the EP4 receptor represents a potential therapeutic strategy for early-stage Alzheimer's disease.
