Chemical inhibition of immune signaling rescues defects during heart development in Down syndrome via regulating canonical Wnt pathway. Chemical inhibition of immune signaling rescues defects during heart development in Down syndrome via regulating canonical Wnt pathway

Congenital heart defects (CHDs) are very frequent in children with Down syndrome (DS), the genetic condition caused by trisomy of chromosome 21 (T21). However, the mechanisms by which T21 causes susceptibility to CHDs are poorly understood. Here, using a combination of human induced pluripotent stem cell (iPSC)-based model and Dp(16)1Yey/+ (Dp16) a mouse model of DS, we identified downregulation of canonical Wnt signaling that is caused by increased dosage of interferon (IFN) receptors encoded on chromosome 21 (HSA21) as a causative factor of CHDs in DS. We differentiated human iPSCs derived from individuals with DS as well as CHDs (DS/CHD iPSCs), and controls (control iPSCs) into cardiac cells. We observed that T21 upregulates IFN signaling, downregulates the canonical WNT pathway, and impairs cardiac differentiation. Furthermore, genetic and pharmacological normalization of IFN pathways restored canonical WNT signaling and rescued defects during cardiac differentiation of DS/CHD iPSCs. Strikingly, treatment with an inhibitor of Janus kinase, which is activated by IFN receptor engagement normalized the canonical Wnt pathway and ameliorated CHDs in Dp16 embryos. Our findings provide new mechanisms underlying CHDs in DS, ultimately aiding the development of novel therapeutic strategies. Overall design: Comparative gene expression profiling analysis of RNA-seq data for: 1) human cells derived from healty controls, patients with Down syndrome as well as congenital heart defects, with or without Wnt signaling activator (CHIR99021) and/or JAK inhibitor (JAKi, Tofacitinib) treatments by using the indicated dosage, harvested at different day points during cardiac differentiation as indicated; 2) E15.5 mouse hearts from WT, Dp16 with or without 10 mg/kg bodyweight/day of JAK inhibitor (JAKi, Tofacitinib) treatments from E6.5 to E14.5, low p-STAT1 indicated the p-STAT1 levels are comparable to WT without JAKi treatment, high p-STAT1 indicated the p-STAT1 levels are significantly higher than WT without JAKi treatment.