Type I Interferon Signaling Augments Autoimmunity in Neuromyelitis Optica Spectrum Disorder

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune disease characterized by anti-aquaporin 4 (AQP4) antibody-mediated astrocyte damage and subsequent demyelination. Prior attempts to treat NMOSD with interferon-beta (IFN-β), a disease-modifying therapy for multiple sclerosis, resulted in worsening of disease activity, with an unknown mechanism. Here, robust activation of the cGAS-STING-IFN-I signaling pathway is identified in myeloid cells in both the periphery and central nervous system. The abnormal IFN-I response gives rise to an increase in the number of AQP4 antigen-specific autoreactive T cells. Sting deficiency can significantly blunt the activation of AQP4-specific T cells, as well as the IFN-I activity in microglia, and attenuate astrocyte damage. Consequently, the clinical manifestation of NMOSD is ameliorated in a passive transfer mouse model of NMOSD. Further, treatment with STING inhibitor H151 alleviates the severity of NMOSD mouse models. These findings uncover the cGAS-STING-IFN-I pathway in promoting autoreactive T cells and establish a foundation for inhibiting this pathway as a new therapeutic revenue for NMOSD.