Maternal immune activation promotes hippocampal kindling epileptogenesis in mice

Objective—Maternal immune activation (MIA) triggered by infections, has been identified as a cause of autism in the 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-6 and interleukin-1β was also addressed. Methods—MIA was induced in C57BL/6 mice by polyinosinic–polycytidylic acid (PIC) injected during embryonic days 12–16. Beginning from postnatal day 40, the propensity of the offspring to epilepsy was examined using hippocampal kindling; autism-like behavior was studied using the sociability test. The involvement of interleukin-6 and interleukin-1β in PIC-induced effects was studied by the co-administration of the cytokine antibodies with PIC, and by delivering recombinant cytokines in lieu of PIC. Results—The 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 interleukin-6 or interleukin-1β . Neither of the recombinant cytokines alone increased the propensity to seizures; however when combined, they produced effects similar to the ones induced by PIC. PIC- induced behavioral deficits were abolished by interleukin-6 antibodies and were mimicked by recombinant interleukin-6; interleukin-1β was not involved. Interpretation—In addition to confirming previously established critical role of interleukin-6 in the development of autism-like behavior following MIA, the present study shows that concurrent involvement of interleukin-6 and interleukin-1β is required for priming the offspring for epilepsy. These data shed light on mechanisms of comorbidity between autism and epilepsy.