A study recently published in International Immunopharmacology revealed an association between neuromyelitis optica spectrum disorder (NMOSD) and elevated levels of glial fibrillary acidic protein (GFAP), suggesting this protein may be useful as a biomarker for the diagnosis and prognosis of this disease and other neurological disorders.
The systematic review conducted by Heimfarth et al evaluated 1152 articles published between 2012 and 2021 from PubMed, Scopus, and Web of Science. After excluding duplicates and those that did not comply with the inclusion criteria, 48 studies that reported GFAP levels in neurological disorders were included, including 4 articles regarding NMOSD. The remaining studies covered multiple sclerosis, frontotemporal lobar degeneration, Alzheimer’s disease, Parkinson’s disease, coronavirus disease 2019 (COVID-19), epileptic seizures, Wilson disease, diabetic ketoacidosis, schizophrenia, autism spectrum disorders, major depressive disorder, glioblastoma, spinal cord injury, asthma, and Friedreich’s ataxia.
A study conducted by Aktas et al measured plasma GFAP levels in patients with NMOSD and healthy controls, revealing averages of 128.3 pg/mL and 1.3 pg/mL, respectively. The authors further described relationships between GFAP and attack risk, disease severity, and treatment effects.
Read more about NMOSD diagnosis
Similarly, Aly et al reported that GFAP could be related to vessel loss, increased foveal avascular zone, and lower foveal thickness. Storoni et al found that serum GFAP levels were significantly higher in patients with neuromyelitis optica (NMO) than in patients with multiple sclerosis optic neuritis, atypical optic neuritis, isolated optic neuritis, relapsing isolated optic neuritis, and chronic relapsing optic neuropathies. Schindler et al concluded that clinical disability and shorter times between attacks were associated with higher GFAP levels. Lastly, Watanabe et al found that serum GFAP levels could predict recent relapses.
Although such results remain important, another study did not show differences in plasma GFAP levels between patients with NMO and healthy individuals.
“It was reported that neuromyelitis optica (NMO), an autoimmune [central nervous system] disease targeting sites of high aquaporin-4 density in the spinal cord and the optic nerve, is associated with a marked loss of astrocytes and increased [cerebrospinal fluid (CSF)] GFAP levels,” the authors wrote. ”In contrast to the CSF GFAP concentration, studies of blood GFAP levels in NMO have been contradictory.”
The authors concluded, “Therefore, elevated levels of GFAP in blood can be a valuable diagnostic biomarker in the evaluation of different neurological diseases. However, the prognostic role of GFAP and the relation of serum GFAP levels with the severity of the disease remain unclear in the literature in respect of some diseases and warrant further study.”
Heimfarth L, Passos FRS, Monteiro BS, Araújo AAS, Quintans Júnior LJ, Quintans JSS. Serum glial fibrillary acidic protein is a body fluid biomarker: a valuable prognostic for neurological disease – a systematic review. Int Immunopharmacol. Published online March 4, 2022. doi:10.1016/j.intimp.2022.108624