Microglia-derived IL-18 remodels hippocampal plasticity to constrain traumatic fear memory
fang, x.; wang, y.; shen, y.; Xie, G.; Liu, R.; Cai, H.; Han, Q.; Xu, X.; Wang, K.; Yin, L.; Di, J.; Zhou, T.; Li, A.; Han, X.; Li, W.; Li, T.
Show abstract
Post-traumatic stress disorder (PTSD) involves complex neuroimmune-synaptic crosstalk in the hippocampus. Here we show that interleukin-18 (IL-18), an extensively studied pro-inflammatory cytokine, serves a protective role against traumatic fear memory through a microglia-to-neuron signaling axis. Traumatic stress induces sustained upregulation of IL-18 in the hippocampus. Exogenous IL-18 administration attenuates fear memory, whereas blockade of IL-18 signaling exacerbates it. Mechanistically, microglial-derived IL-18 acts on neuronal IL-18R1 to restore stress-impaired synaptic plasticity and reduce perineuronal net density, thereby facilitating structural synaptic remodeling. In addition, IL-18 modulates the synaptic organization of fear memory-encoding engram cells within hippocampal ensembles. Together, these findings redefine IL-18 as a homeostatic regulator of post-trauma hippocampal synaptic function and identify the hippocampal IL-18 pathway as a potential therapeutic target for PTSD.
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