Neurofilament light protein and glial fibrillary acidic protein as biological markers in MS

Objective: To determine if CNS-derived proteins present in the CSF of multiple sclerosis ( MS) patients reflect different pathologic processes of MS and if these proteins could be useful as biologic markers of disease activity. Methods: Concentrations of the neurofilament light protein (NFL), glial fibrillary acidic protein (GFAP), S100B, and the neuron-specific enolase protein (NSE) were determined in the CSF of 66 MS patients and 50 healthy control subjects with immunoassays. Results: The mean levels of the NFL were increased during all stages of MS compared with controls (p < 0.001), peaking almost 10 times higher during acute relapses. The highest levels of GFAP were found during the secondary progressive course (p < 0.001) with a strong correlation with neurologic deficits ( Expanded Disability Status Scale score, r = 0.73, p < 0.001). No increase of S100B or NSE protein was found in the CSF of MS patients compared with control subjects. Conclusions: Increased level of NFL is a general feature of MS, indicating continuous axonal damage during the entire course of the disease with the most profound damage during acute relapses. GFAP may serve as a biomarker for disease progression, probably reflecting the increasing rate of astrogliosis.