Biological markers in CSF and blood for axonal degeneration in multiple sclerosis

Biomarkers in body fluids could help to predict and monitor neurological decline in people with multiple sclerosis (MS). We discuss markers for axonal damage in body fluids in people with MS. The most promising axonal marker for discriminating patients with MS from those with other neurological diseases is the neurofilament light chain in CSF. Antibodies against the heavy-chain isoform are associated with disease progression. Other studies have shown altered CSF concentrations of tau proteins, actin, tubulin, and 14-3-3 protein. Interestingly, the concentration of 24S-hydroxycholesterol was decreased in serum of patients with MS. No clear changes have been shown for the markers apolipoprotein E and neurospecific enolase. We describe three types of markers for axonal damage: markers that reflect processes in the CNS, those that reflect extraneural processes, and those that reflect whole-body changes. These concepts may be helpful for biomarker research in various neurodegenerative diseases.