Antiviral signalling in human IPSC-derived neurons recapitulates neurodevelopmental disorder phenotypes

Maternal immune activation increases the risk of neurodevelopmental disorders. Elevated cytokines, such as interferon-gamma (IFNγ), in offspring9s brains play a central role. IFNγ activates an antiviral cellular state, limiting viral entry and replication. In addition, IFNγ has been implicated in brain development. Here, we hypothesise that IFNγ-induced antiviral signalling contributes to molecular and cellular phenotypes associated with neurodevelopmental disorders. We find that transient IFNγ treatment of neural progenitors derived from human induced pluripotent stem cells (hIPSCs) persistently increases neurite outgrowth, phenocopying hIPSC-neurons from autistic individuals. IFNγ upregulates antiviral PML bodies and MHC class I (MHCI) genes, which persists through neuronal differentiation. Critically, IFNγ-induced neurite outgrowth requires both PML and MHCI. We also find that IFNγ disproportionately alters expression of autism and schizophrenia risk genes, suggesting convergence between these genetic and environmental risk factors. Together, these data indicate that IFNγ-induced antiviral signalling may contribute to neurodevelopmental disorder aetiology.