Serum levels of glial fibrillary acidic protein are associated with damage to the afferent visual system in patients with clinically stable aquaporin-4 immunoglobulin G-positive (AQP4-IgG+) neuromyelitis optica spectrum disorder (NMOSD), according to a study published in Multiple Sclerosis and Related Disorders.
The protein could, therefore, be a sensitive marker for disease severity and “add to the growing evidence for subclinical disease activity in NMOSD,” according to the authors.
Glial fibrillary acidic protein is a protein derived from astrocytes. It is known to be associated with disease severity in AQP4-IgG+ NMOSD.
Here, the researchers wanted to explore the associations of serum levels of glial fibrillary acidic protein and neurofilament light, a marker of neuroaxonal damage, with subclinical afferent visual system damage in patients with clinically stable AQP4-IgG+ NMOSD.
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To do so, they measured the levels of glial fibrillary acidic protein and neurofilament light in the serum of 33 patients with clinically stable AQP4-IgG+ NMOSD and 16 control patients with myelin oligodendrocyte glycoprotein antibody-associated disease.
The results showed that higher levels of glial fibrillary acidic protein were associated with a thinner ganglion cell-inner plexiform layer and shallower fovea in the eyes of NMOSD patients without optic neuritis.
Moreover, participants with pathological P100 latency had higher serum glial fibrillary acidic protein levels.
The researchers concluded that the association of serum glial fibrillary acidic protein levels with structural and functional markers of afferent visual system damage without optic neuritis suggests that the protein may be a sensitive biomarker of disease severity in patients with clinically stable AQP4-IgG+ NMOSD.
However, they added that more research is needed to validate these findings and that despite its emerging role as a biomarker in NMOSD, the potential value of serum glial fibrillary acidic protein level in individual patients with the disease “currently remains elusive.”
Lin TY, Schindler P, Grittner U, et al. Serum glial fibrillary acidic protein correlates with retinal structural damage in aquaporin-4 antibody positive neuromyelitis optica spectrum disorder. Mult Scler Relat Disord. Published online August 9, 2022. doi:10.1016/j.msard.2022.104100