ASD is a considered to be the result of complex interactions among genetic and environmental factors, suggesting that the rising incidence of ASD in the past decades can be largely attributed to environmental insults such as maternal infections. However, research using animal models for autism have individually focused on either genetic mutations, pharmacological disruptors or immune activation. The goal of this application is to develop a novel dual-hit mouse model to study gene x environment interactions. Our studies will test the hypothesis that a short increase in the hub cytokine IL-6 during a critical period of neural development will exacerbate the behavioral and synaptic phenotypes in a genetic model of ASD. For these studies we will inject IL-6 into neonatal heterozygous Shank3Δ4-22 mice. While the Shank3Δ4-22 homozygous mice have a penetrant phenotype, the heterozygous mice have only a mild sociability phenotype. Our experiments will test the hypothesis that modestly elevating IL-6 will exacerbate the behavioral and synaptic phenotypes of this genetic model of ASD. Shank3Δ4-22 mice will be administered either PBS or 40 ng rmIL-6 twice daily from P3-P7. We will evaluate male mice as juveniles and as young adults for those core behaviors relevant to ASD (sociability, repetitive behavior, and communication). To assess more complex behaviors the mice will be evaluated using the paired associates learning (PAL) task to evaluate spatial memory, attention and response control, the Barnes Maze, the passive avoidance test to measure avoidance memory and the elevated plus maze to assess anxiety. In Aim 2 we will evaluate the levels of astrocyte-produced proteins that are known to regulate synaptogenesis at P21 and levels of glutamate receptors and glutamate handling proteins. Additional work will evaluate dendritic complexity, spine numbers, spine types and perineuronal nets in the dorsal hippocampus and prefrontal cortex. We anticipate that upon completing these studies, that we will have established a novel dual-hit model for ASD allowing us to gain new insights into gene x environment interactions that are remarkably understudied in the context of autism. This new model will provide conceptual advancements for how gene mutations important for ASD and inflammatory cytokines intersect to affect neuronal maturation and synaptogenesis. The etiology of high functioning ASD, which affects over 40% of people with ASD, remains enigmatic and lacks a relevant animal model. Therefore, we predict that this new dual hit model will be widely adopted by ASD researchers to enable them to identify and test therapeutics for their ability to decrease the penetrance of the negative aspects of ASD while preserving cognitive function.

Research using animal models for autism have individually focused on either genetic mutations, pharmacological disruptors or immune activation. The goal of this application is to develop a novel dual-hit mouse model to study gene x environment interactions. Our studies will test the hypothesis that a short increase in the hub cytokine IL-6 during a critical period of neural development will produce robust behavioral and synaptic changes in heterozygous Shank3Δ4-22 mice, which otherwise have only a mild sociability phenotype.