Maternal granulocyte colony-stimulating factor alters synaptic maturation and social behaviors in offspring

Neurodevelopmental disorders, including autism spectrum disorder (ASD), arise from complex interactions between genetic and environmental factors. Maternal immune activation (MIA) is a key environmental risk factor that disrupts embryonic neurodevelopment, primarily through inflammatory cytokines. However, the contribution of non-inflammatory cytokines, particularly hematopoietic growth factors, remains poorly understood. Here, we identified granulocyte colony-stimulating factor (G-CSF) as a candidate mediator of MIA-induced neurodevelopmental alterations. Polyinosinic:polycytidylic acid [poly(I:C)] administration to pregnant dams at embryonic day 12.5 (E12.5) significantly increased G-CSF levels in both maternal plasma and embryonic tissue. To assess its contribution to neurodevelopmental alterations, we administered human G-CSF (hG-CSF) to pregnant dams at E12.5. At the structural level, male offspring exposed to prenatal hG-CSF showed increased dendritic spine density and a higher proportion of immature spines in the medial prefrontal cortex. Behaviorally, both male and female offspring exhibited altered social preference. Bulk RNA-seq analysis of the prefrontal cortex revealed altered enrichment of pathways related to synapse organization, translation, and mitochondrial function in both sexes, with opposite directions of enrichment in males and females. In vitro, G-CSF attenuated synapse maturation and enhanced microglial phagocytic activity. These findings suggest that G-CSF may contribute to MIA-associated neurodevelopmental alterations, potentially through disrupted synapse maturation and microglial function. Our results highlight a hematopoietic pathway that may contribute to mechanisms underlying neurodevelopmental disorders, including ASD.