Pathogenic T cell responses against aquaporin 4

Area of Science:

• Neuroimmunology
• Autoimmunity
• Central Nervous System Inflammation

Background:

• Neuromyelitis Optica (NMO) lesions involve T cells, aquaporin-4 (AQP4)-specific antibodies, and complement.
• The role of AQP4-specific T cells in NMO lesion development remains unclear.

Purpose of the Study:

• To investigate the pathogenic potential of AQP4-specific T cells in NMO lesion formation.
• To determine if AQP4-specific T cells contribute to NMO pathogenesis independently or in concert with autoantibodies.

Main Methods:

• Generation of AQP4-specific T cell lines in Lewis rats.
• Characterization of T cell pathogenicity with and without NMO patient-derived AQP4-specific autoantibodies.
• Assessment of inflammatory lesions in the central nervous system, kidneys, and muscles.

Main Results:

• AQP4-specific T cells induced brain inflammation, targeting the astrocytic glia limitans.
• T cell-induced inflammation facilitated autoantibody entry, leading to NMO-like spinal cord and brain lesions.
• Transfer of T cells also caused subclinical myositis and interstitial nephritis.
• Gamma-interferon induced the NMO antibody epitope in kidney cells.

Conclusions:

• AQP4-specific T cells play a significant role in initiating central nervous system inflammation in NMO.
• NMO lesion development likely results from a synergistic interaction between T cell-mediated and humoral immune responses against AQP4.
• These findings highlight the complex immunopathology of Neuromyelitis Optica.