RNaseT2 deficient mice reveal the interferon-driven brain phenotype of congenital CMV infection and type I interferonopathies

Infantile-onset RNaseT2 deficient leukoencephalopathy is characterised by cystic brain lesions, multifocal white matter alterations, cerebral atrophy, and severe psychomotor impairment. The phenotype is indistinguishable from congenital cytomegalovirus brain infection and overlaps with typeI interferonopathies like Aicardi-Goutières syndrome, strongly suggesting a role for innate immunity in its pathophysiology. To date, pathophysiological studies have been hindered by the lack of mouse models recapitulating the neuroinflammatory encephalopathy found in patients. In this study, we generated Rnaset2-/- mice using CRISPR/Cas9-mediated genome editing. Strikingly, Rnaset2-/- mice revealed strong upregulation of interferon-stimulated genes and concurrent neuroinflammation, with infiltration of CD8+ effector memory T cells and inflammatory monocytes into the grey and white matter. Homeostatic dysfunctions in glia cells and neurons revealed by single nuclei RNA sequencing provides initial insights into the mechanism of hippocampal-accentuated brain atrophy and cognitive impairment. Thus, Rnaset2 -/- mice provide an important model, to develop therapies for inborn RNaseT2 deficiency, congenital viral brain infection and further type I interferonopathies. Single Cell Sequencing from hippocampus and putamen of RNaseT2 knockout mice and controls