Primary and secondary progressive forms of multiple sclerosis (PPMS and SPMS) have different pathological characteristics. However, it is unknown whether neurodegenerative mechanisms are shared. We measured cerebrospinal fluid (CSF) levels of neurofilament (Nf) light and heavy isoforms and N-acetylaspartic acid (NAA) in 21 PP, 10 SPMS patients and 15 non-inflammatory neurological disease controls (NINDC). Biomarkers were related to Expanded Disability Status Scale (EDSS) and Multiple Sclerosis Severity Score (MSSS) over a long period of follow-up [median (interquartile range) 9 (5.5-12.5) years] in 19 PPMS and 4 SPMS patients, and to T2 lesion load, T1 lesion load, and brain parenchymal fraction at the time of lumbar puncture. Nf light was higher in PPMS (p < 0.005) and Nf heavy was increased in both SPMS and PPMS (p < 0.05 and p < 0.01) compared to NINDC, but were comparable between the two MS subtypes. Nf heavy was a predictor of the ongoing disability measured by MSSS (R2 = 0.17, β = 0.413; p < 0.05). Conversely, Nf light was the only predictor of the EDSS annual increase (R 2 = 0.195, β = 0.441; p < 0.05). The frequency of abnormal biomarkers did not differ between the two MS progressive subtypes. Our data suggest that PP and SPMS likely share similar mechanisms of axonal damage. Moreover, Nf heavy can be a biomarker of ongoing axonal damage. Conversely, Nf light can be used as a prognostic marker for accumulating disability suggesting it as a good tool for possible treatment monitoring in the progressive MS forms.
Trentini A, Comabella M, Tintoré M, Koel-Simmelink MJ, Killestein J, Roos B, Rovira A, Korth C, Ottis P, Blankenstein MA, Montalban X, Bellini T, Teunissen CE. N-Acetylaspartate and neurofilaments as biomarkers of axonal damage in patients with progressive forms of multiple sclerosis. J Neurol. 2014 Sep [Epub ahead of print]
Yet more evidence that neurofilament a nerve protein in nerves is released during nerve damage and it can be measured to give an indication of disease worsening.