Synapse loss induced by interleukin-1β requires pre- and post-synaptic mechanisms

Area of Science:

• Neuroscience
• Cell Biology
• Immunology

Background:

• Interleukin-1β (IL-1β) is a key inflammatory cytokine impacting neuronal health.
• Synaptic function is crucial for neuronal communication and survival.
• Dysregulation of IL-1β is implicated in neuroinflammatory diseases.

Purpose of the Study:

• To investigate the precise mechanisms by which IL-1β affects synaptic structures in rat hippocampal neurons.
• To identify the specific molecular pathways involved in IL-1β-induced synapse loss.

Main Methods:

• Primary rat hippocampal neuron cultures were utilized.
• An imaging-based assay quantified postsynaptic density 95 (PSD-95) clusters to assess synaptic sites.
• Pharmacological agents were used to probe signaling pathways, including COX2, Src kinase, and NMDA receptors.

Main Results:

• IL-1β treatment (24h) resulted in a significant loss of synaptic sites (23% ± 3%).
• Synapse loss was dependent on IL-1 receptor activation, COX2-mediated prostaglandin production, and postsynaptic Src kinase activation.
• Presynaptic glutamate release and subsequent NMDA receptor activation were essential for IL-1β-induced synapse elimination.
• Prostaglandin E2 (PGE2) induced synapse loss only when Src kinase was activated.

Conclusions:

• IL-1β reduces synaptic connections through a complex interplay of pre- and postsynaptic signaling.
• The study identifies specific molecular targets (IL-1 receptor, COX2, Src, NMDA receptors) critical for IL-1β's effects on synapses.
• These findings offer potential therapeutic targets for neuroinflammatory conditions impacting synaptic integrity.