CFHR2 supplementation mitigates pathologies of neuromyelitis optica by regulating complement activation.

Neuromyelitis optica spectrum disorder (NMOSD) is a relapsing autoimmune disease primarily affecting the optic nerves and spinal cord. While the pathogenesis of NMO involves Aquaporin-4 antibodies (AQP4-IgG) and complement-mediated damage, the specific roles of the complement pathway remain to be fully elucidated. In this study, we found that complement factor H-related protein 2 (CFHR2), a regulator that inhibits the complement C3 alternative pathway, was significantly decreased in the serum of NMO patients and was negatively correlated with the Expanded Disability Status Scale (EDSS) score. Furthermore, we observed a marked reduction in CFHR2 expression in astrocytes in both in vitro and in vivo NMO models. Administration of recombinant human CFHR2 protein or adeno-associated virus (AAV)-mediated overexpression of CFHR2 in astrocytes significantly alleviated NMO-related lesions and motor deficits by inhibiting inflammation in these models. Additionally, CFHR2-modified functionalized exosomes demonstrated efficacy in improving NMO-related lesions and motor dysfunction, offering a promising new therapeutic strategy for NMO.