Research Assistant Professor Northwestern Univ. Feinberg Sch. of Med., Illinois, United States
Disclosure(s):
Gabriel Arellano, PhD: No financial relationships to disclose
Introduction/Rationale: Neuromyelitis optica is a severe autoimmune disease of the central nervous system (CNS), mediated by autoantibody and Th17 responses to Aquaporin-4 (AQP4), a water channel protein highly expressed in astrocyte end feet. Despite its clinical importance, understanding NMOSD pathogenesis remains challenging due to its low incidence and the lack of reliable animal models that recapitulate the human disease.
Methods: We recently established a robust model by immunizing wild-type (WT) mice with the pathogenic AQP4 201-220 peptide and pertussis toxin. Strong disease only develops when IFN-γ is blocked in WT mice or absent, as in IFN-γ receptor knockout (IFNGRKO) mice, both mimicking key features of human NMOSD.
Results: Here, we demonstrate that disease is dependent on anti-AQP4 antibodies and antigen-specific T and B cells. To investigate mechanisms of disease progression and whether immune tolerance could be re-established, we compared WT, IFNGRKO, and IFNGRKO mice treated with tolerogenic PLGA nanoparticles encapsulating AQP4 peptide (PLGA(AQP4)) at day 28 post-immunization. Single-cell RNA-sequencing and immune repertoire analysis of CNS and spleen revealed major immune alterations. IFNGRKO mice showed CNS infiltration by clonally expanded CD4⁺ Th1/Th17 and CD8⁺ T cells, a strong type I interferon (IFN-I) gene signature (ISGs), and inflammatory reprogramming of microglia toward MHC-II⁺ states. B cell repertoires were skewed, with reduced diversity, somatic hypermutation, and plasmablast/memory expansion. PLGA(AQP4) treatment reversed these features, reducing T cell infiltration, suppressing ISGs, restoring microglial homeostasis, and limiting B cell clonal expansion and epitope spreading.
Conclusion: Our findings show that NMOSD is driven by antigen-specific T and B cell responses, amplified by IFN-I and innate CNS dysregulation. PLGA(AQP4) therapy re-establishes tolerance and offers a translational strategy for CNS autoimmunity.
