Astrocytic damage in glial fibrillary acidic protein astrocytopathy during initial attack

Abstract

Objective: Determination of glial fibrillary acidic protein (GFAP), aquaporin 4 (AQP4), and myelin oligodendrocyte glycoprotein (MOG) levels in cerebrospinal fluid (CSF), and astrocytic damage analysis in patients with GFAP astrocytopathy (GFAP-A) and other conditions.

Methods: GFAP, AQP4, and MOG levels in CSF were detected via enzyme-linked immunosorbent assays. Anti-GFAP, anti-AQP4, and anti-MOG IgGs were detected via indirect immunofluorescence assays.

Results: In 32 GFAP-Astrocytopathy patients, CSF GFAP was significantly higher during acute exacerbation than it was in patients with MOG encephalomyelitis, multiple sclerosis, autoimmune encephalitis, and an "other inflammatory neurological disorders" group (all p < 0.0001). CSF GFAP levels were slightly higher in the GFAP-A group than in an anti-AQP4 IgG-positive neuromyelitis optica spectrum disorder group (p = 0.012). There were no significant differences between the CSF MOG and AQP4 levels in the GFAP-A group and those of other groups. CSF GFAP levels were significantly reduced after steroid treatment (p = 0.011). CSF GFAP levels differed significantly in GFAP-Astrocytopathy patients with and without encephalitis (p = 0.016). In GFAP-Astrocytopathy patients, CSF GFAP was correlated with Expanded Disability Status Scale (EDSS) score during attack (r = 0.545, p = 0.001). In follow-up examinations however, in GFAP-Astrocytopathy patients CSF GFAP level was not correlated with EDSS score 6 months later.

Conclusions: CSF GFAP level and pathological examination of GFAP-Astrocytopathy patients revealed astrocyte damage. CSF GFAP level was associated with steroid treatment at the acute stage, therefore CSF GFAP may be a sensitive biomarker with respect to the effects of therapy during the acute stage.

Keywords: Antibody; Aquaporin 4; Astrocyte; Cerebral spinal fluid; Glial fibrillary acidic protein.