Serum neurofilament light chain is a biomarker of acute and chronic neuronal damage in early multiple sclerosis

Monitoring neuronal injury remains one key challenge in early relapsing-remitting multiple sclerosis (RRMS) patients. Upon axonal damage, neurofilament – a major component of the neuro-axonal cytoskeleton – is released into the cerebrospinal fluid (CSF) and subsequently peripheral blood. To investigate the relevance of serum neurofilament light chain (sNfL) for acute and chronic axonal damage in early RRMS. sNfL levels were determined in 74 patients (63 therapy-naive) with recently diagnosed clinically isolated syndrome (CIS) or RRMS using Single Molecule Array technology. Standardized 3？T magnetic resonance imaging (MRI) was performed at baseline and 1–3 consecutive follow-ups (42 patients; range: 6–37？months). Baseline sNfL correlated significantly with T2 lesion volume (r？=？0.555, p？<？0.0001). There was no correlation between baseline sNfL and age, Expanded Disability Status Scale (EDSS) score or other calculated MRI measures. However, T2 lesion volume increased (r？=？0.67, p？<？0.0001) and brain parenchymal volume decreased more rapidly in patients with higher baseline sNfL (r？=？？0.623, p？=？0.0004). Gd-enhancing lesions correlated positively with sNfL levels. Initiation of disease-modifying treatment led to a significant decrease in sNfL levels. sNfL indicates acute inflammation as demonstrated by correlation with Gd+ lesions. It is a promising biomarker for neuro-axonal damage in early multiple sclerosis (MS) patients, since higher baseline sNfL levels predicted future brain atrophy within 2？years