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Cerebrospinal fluid level of neurofilament light chain is associated with increased disease activity in neuro-Behçet's disease.

BACKGROUND
Clinical exacerbations characterized with neurological symptoms are observed in around 10% of Behçet's disease (BD) patients and may culminate in severe disability. Although certain immunological factors have been associated with disease activity in neuro-Behçet's disease (NBD), biomarkers for monitoring the clinical outcome of NBD have not been properly investigated.


METHODS
Levels of neurofilament light chain (NFL), homeobox protein Hox-B3 (HoxB3), and YKL-40 were measured in cerebrospinal fluid (CSF) samples of 23 parenchymal (n = 16) and nonparenchymal (n = 7) NBD patients obtained during NBD attacks by ELISA. Parameters of clinical progression and outcome were assessed for an average follow-up period of 3.9 ± 1.3 years.


RESULTS
Parenchymal NBD patients showed elevated CSF levels of NFL, HoxB3, and YKL-40 as compared to nonparenchymal patients. NBD patients showing an increase in modified Rankin score (mRS) values during follow-up had significantly higher CSF NFL levels. Patients with relatively lower CSF NFL levels (<1000 ng/L) did not develop attacks or cognitive impairment interfering with daily life activities during follow-up. NFL levels correlated with disease duration and mRS at the last follow-up visit, while HoxB3 levels correlated with a number of attacks during follow-up.


DISCUSSION
CSF level of NFL appears to predict the prospective somatic and cognitive disability in NBD patients and may thus be potentially used as a biomarker of clinical outcome in this disease.