Cerebrospinal fluid light and heavy neurofilaments in neuromyelitis optica.

Background: Axonal injury is the correlate of disease progression in NMO and MS. Neurofilament (Nf) belongs to neuron specific intermediate filaments located in axons. Nf protein subunits are potential biomarkers in cerebrospinal fluid (CSF) for acute axonal injury. However, whether CSF NfH and NfL levels are elevated in NMO patients has remained unclear.

Methods: Nf light subunit (NfL) and Nf heavy subunit NfH in cerebrospinal fluid were measured by enzyme-linked immunosorbent assay (ELISA) in NMO (n=32), MS (n=25), and other non-inflammatory neurological disease patients (OND, n=18).

Results: CSF pNf-H levels were increased in the NMO patients compared with OND patients (p=0.001). CSF NfL levels in the NMO patients were also higher compared with MS patients (p=0.001), and OND patients (p=0.000001). When comparing NfL levels between MS and OND patients, there also significant differences (p=0.0003). NMO and MS patients revealed a trend to an increased disability with increased CSF NfL during relapse (NMO: p=0.006; MS: p=0.017). There is positive relationship between CSF pNf-H and disability of MS patients (p=0.041).

Conclusions: CSF levels of NfL are increased in NMO patients and reflect the disease severity in NMO.