Cerebrospinal fluid interleukin-6 may be a biomarker for conversion of clinically isolated syndrome to neuromyelitis optica spectrum disorder

Abstract

Objective

To evaluated the predictive value of several cerebrospinal fluid (CSF) cytokines in the conversion of clinically isolated syndrome (CIS) patients to neuromyelitis optica spectrum disorder (NMOSD) or multiple sclerosis (MS).

Methods

We enrolled 33 CIS patients whose CSF samples were collected during the acute phase of the first onset before immunotherapy. The CSF levels of interleukin (IL)-2, IL-4, IL-6, IL-10, IL-13, IL-17A, IL-21, IL-23, interferon-γ (IFN-γ) and transforming growth factor beta 1 (TGF-β1) were measured using the human cytokine multiplex assay or ELISA. Patients were seen every 3 to 6 months. Unscheduled visits occur in case of exacerbations. Clinical measures of disease progression were recorded.

Results

The mean follow-up of CIS patients was 23.2 ± 7.9 months. Six patients converted to NMOSD, six patients converted to MS. The CSF IL-21 and IL-6 levels were significantly elevated in CIS patients converted to NMOSD than those who did not. High CSF IL-6 levels are a predictor of conversion to NMOSD in patients with CIS and are associated with a shorter time to conversion. Increased CSF IL-6 levels correlated with CSF WBC count, protein level and IgG index, segment of myelitis, EDSS scores. There was no significant difference in cytokine levels between patients who converted to MS and those who did not.

Conclusions

These findings validate CSF IL-6 as an independent predictive factor for the risk of clinical conversion to NMOSD in CIS. The above CSF cytokines levels in CIS patients can't predict conversion to MS.