Maternal Immune Activation Promotes Hippocampal Kindling Epileptogenesis in Mice

ObjectiveMaternal immune activation (MIA) triggered by infections has been identified as a cause of autism in offspring. Considering the involvement of perturbations in innate immunity in epilepsy, we examined whether MIA represents a risk factor for epilepsy as well. The role of specific MIA components interleukin (IL)-6 and IL-1 was also addressed. MethodsMIA was induced in C57BL/6 mice by polyinosinic-polycytidylic acid (PIC) injected during embryonic days 12 to 16. Beginning from postnatal day 40, the propensity of the offspring to epilepsy was examined using hippocampal kindling; autismlike behavior was studied using the sociability test. The involvement of IL-6 and IL-1 in PIC-induced effects was studied by the coadministration of the cytokine antibodies with PIC, and by delivering recombinant cytokines in lieu of PIC. ResultsThe offspring of PIC-exposed mice exhibited increased hippocampal excitability, accelerated kindling rate, prolonged increase of seizure susceptibility after kindling, and diminished sociability. Epileptic impairments were abolished by antibodies to IL-6 or IL-1. Neither of the recombinant cytokines alone increased the propensity to seizures; however, when combined, they produced effects similar to those induced by PIC. PIC-induced behavioral deficits were abolished by IL-6 antibodies and were mimicked by recombinant IL-6; IL-1 was not involved. InterpretationIn addition to confirming the previously established critical role of IL-6 in the development of autismlike behavior following MIA, the present study shows that concurrent involvement of IL-6 and IL-1 is required for priming the offspring for epilepsy. These data shed light on mechanisms of comorbidity between autism and epilepsy. Ann Neurol 2013;74:11-19