Spatial encoding of cytokine signals in the developing human brain: dissecting type I interferon responses in NSCs niches using human brain organoids

Environmental and genetic risk factors may cause neurodevelopmental disorders through Type I interferons (IFN-I)-mediated responses. However, how neural stem cells (NSCs) respond to IFN-I within developing human brain remains unknown. We developed ISRE:tdTomato, an IFN-responsive fluorescent reporter system, which was inserted into H9 hESCs to study IFN-I pathway activation. These were used to generate human forebrain organoids. 22-day-old organoids were exposed to different IFN-I doses for 48h. Analysis were performed at 48h and 10 days post-IFN-I washout. Data reveal dose-mediated heterogeneity in NSC IFN-I responsiveness: low doses weakly activate restricted radial glia subsets only; higher doses strongly activate an increased number of radial glia cells. Reporter activation concentrates in discrete ventricular zone regions. Moreover, preliminary evidence suggests transient IFN-I exposure induces persistent reporter activity and increases radial glia population 10 days post-exposure, indicating potential long-term effects. Our findings reveal that developing human neural tissue shows dose- and spatially-dependent NSC responsiveness to type I IFN signals, with tissue architecture constraining cytokine accessibility and NSC competence. Understanding this acute and persistent responsiveness is essential for interpreting how dysregulation of the IFN-I axis contributes to neurodevelopmental disorders and for developing IFN-I targeted therapies.