Targeting microglial EP4 receptor activation to treat multiple sclerosis

Overview

This research program investigates the microglial EP4 signaling pathway as a therapeutic target for multiple sclerosis (MS) and other demyelinating diseases. The approach centers on activating the prostaglandin PGE2 receptor EP4 on microglia — the brain's resident immune cells — to enhance their phagocytic capacity, accelerate clearance of myelin debris, and ultimately improve clinical outcomes in demyelinating disease models.

The rationale is grounded in human genetic and clinical evidence: genetic variations in the Ptger4 gene (which encodes EP4) are linked to MS susceptibility, MS patients show elevated PGE2 levels in cerebrospinal fluid alongside reduced Ptger4 expression, and prior animal studies demonstrate that systemic EP4 agonism improves symptoms while antagonism worsens them. This program extends those findings by focusing specifically on the microglial EP4 pathway.

Technical specifications

Core mechanism:

• Selective activation of the EP4 receptor on microglia using small-molecule agonists
• Targeted delivery routes include intracerebroventricular and intraparenchymal administration directly into the cerebral cortex
• Conditional knockout mouse line (CX3CR1-EP4 KO) used to confirm pathway necessity

Validation approaches:

• In vitro phagocytosis assays using microglial cells treated with EP4 agonist
• Cuprizone-induced demyelination model combined with EP4 agonist administration to assess myelin debris clearance
• MOG-induced experimental autoimmune encephalomyelitis (EAE) model evaluating clinical scores and myelin debris clearance at two intervention windows: before symptom onset and after symptom onset
• Morphological and molecular profiling of microglia (CD68 expression, phagocytosis gene panels, morphological complexity)

Key demonstrated findings:

• EP4 agonist promotes bead phagocytosis by microglial cells in vitro
• Intracerebroventricular EP4 agonist increases microglial CD68 expression in wildtype mice, an effect absent in CX3CR1-EP4 KO mice
• High-fat diet-induced upregulation of phagocytosis genes is prevented when microglia lack EP4

Technology readiness level

This research is at the preclinical discovery and validation stage. Prior work has established proof-of-concept that microglial EP4 activation enhances phagocytosis and modulates microglial morphology in vivo. The proposed studies will extend these findings into clinically relevant demyelination and EAE models to determine therapeutic efficacy and optimal intervention timing. The program is currently seeking partnership support for reagent acquisitions, EAE model generation, and personnel funding to advance toward translational development. Additional considerations include the route of administration (intracerebral delivery in current models) and the need to establish systemic delivery feasibility before clinical translation.