Correcting Autoinflammation in STING-Associated Vasculopathy with Onset in Infancy (SAVI) by Human Stem Cell Genome-Editing

Type I interferonopathies comprise a large group of Mendelian autoinflammatory diseases that generally lack effective treatments. STING-associated Vasculitis with onset in Infancy (SAVI) is a severe autosomal dominant disease due to gain-of-functon(GOF) mutations in the gene STING1, encoding for the Stimulator of Interferon Response CGAMP Interactor 1 (STING1). SAVI leads to a severe multisystemic disease comprising systemic vasculitis and lung fibrosis. A possible therapeutic approach is to engineer the patient’s hematopoietic system to restore interferon homeostasis, thereby preventing chronic inflammation and organ damage and halting disease development. Here, we describe a “universal” genome editing correction strategy using CRISPR/Cas9 that targets the stimulator of interferon response cGAMP interactor 1 (STING1) gene at the endogenous locus in SAVI patient-derived induced pluripotent stem cells (iPSCs) and in human CD34+ hematopoietic stem and progenitor cells (HSPCs). The engineered SAVI-iPSCs express normal levels of STING1 protein following differentiation into monocytes and macrophages and no longer produce interferon-alpha (IFN-α) at a basal state. Using SAVI-gene-engineered HSPCs, we determined the minimum fraction of mutant alleles required to induce spontaneous IFN-α production, thus establishing the threshold of genome correction necessary to rescue the disease. Finally, we demonstrated engineered CD34+ HSPCs at the STING1 locus retain regenerative potential by supporting long-term repopulating capacity and multi-lineage differentiation potential following transplantation into immunocompromised mice. Together, these studies established the rationale for the clinical translation of SAVI genome editing and a therapeutic framework for correcting other type I interferonopathies.