Cytokine-mediated immune-to-brain signaling in neural circuit disorders.

Neuroinflammation has emerged as a fundamental driver of neural circuit dysfunctions across a spectrum of neurodevelopmental and psychiatric disorders. Beyond classical neuroimmune pathologies, accumulating evidence indicates that systemic inflammatory states - including those elicited by infection, metabolic dysfunction, stress, or peripheral immune activation - induce profound and long-lasting alterations in brain development and function. Cytokines act as critical molecular mediators of this peripheral-to-central immune communication, precisely orchestrating microglial activation in a spatiotemporally restricted manner. Inflammasome-dependent signaling, particularly NLRP3 activation and subsequent cytokine release, has a central role in shaping microglial states during neuroinflammation. Here, we integrate current evidence linking systemic inflammation to microglial cytokine signaling programs and discuss how these cascades shape synaptic development, refinement, and circuit function. Although synapse pruning and cytokine-mediated microglial signaling jointly contribute to circuit remodeling, we highlight cytokine-driven microglial state amplification as a central mechanism linking systemic inflammation to neural circuit instability. We also highlight that specific cytokines can exert direct effects on neuronal populations - independent of microglial intermediates - to context-dependently modulate synaptic efficacy and circuit excitability. Finally, we evaluate the mechanisms linking systemic inflammation to brain dysfunction and highlight emerging translational opportunities, including the therapeutic repurposing of cytokine-targeting and immunomodulatory agents for neuropsychiatric interventions.