Takashi Fujita

Chronic and aberrant nucleic acid sensing causes type I IFN–driven autoimmune diseases, designated type I interferonopathies. We found a significant reduction of regulatory T cells (T regs ) in patients with type I interferonopathies caused by mutations in ADAR1 or IFIH1 (encoding MDA5). We analyzed the underlying mechanisms using murine models and found that T reg -specific deletion of Adar1 caused peripheral T reg loss and scurfy -like lethal autoimmune disorders. Similarly, knock-in mice with T reg -specific expression of an MDA5 gain-of-function mutant caused apoptosis of peripheral T regs and severe autoimmunity. Moreover, the impact of ADAR1 deficiency on T regs is multifaceted, involving both MDA5 and PKR sensing. Together, our results highlight the dysregulation of T reg homeostasis by intrinsic aberrant RNA sensing as a potential determinant for type I interferonopathies.

Rabies virus (RABV) is a neglected zoonotic pathogen that causes lethal infections in almost all mammalian hosts, including humans. Recently, RABV has been reported to induce intracellular formation of stress granules (SGs), also known as platforms that activate innate immune responses.