Proteome analysis of cerebrospinal fluid in patients with multiple sclerosis

Background: Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of unknown cause. Although diagnostic criteria for early MS are available, there is still a need for biomarkers predicting disease subtype and progression. Therefore, we had analyzed the cerebrospinal fluid (CSF) proteome profile of MS patients by 2-dimensional difference in-gel electrophoresis (2-D-DIGE) technology. Our previous results showed clear differences in the proteome profile of patients with RRMS and CIS as compared to normal controls. For validation of these findings and to evaluate the diagnostic sensitivity and specificity of 2-D electrophoresis we have continued the experiments using different immunoassay techniques.

Methods: CSF samples from 5 single patients with relapsing remitting MS (RRMS, mean age 34 years; median disease duration 24 months) and from 5 single patients with clinically isolated syndrome (CIS, mean age 35 years; median disease duration 3 weeks) were analyzed and compared to age matched normal controls (mean age 37 years). All MS and CIS patients received a lumbar puncture during an acute relapse. CSF samples were analyzed by immunoblot analysis and sandwich enzyme immunoassay (ELISA) technique.

Results: With immunoblot analysis we were able to confirm the differences of three different proteins formerly found to be up- or down-regulated in RRMS and CIS compared with controls by 2-D DIGE technique. In native CIS and RRMS samples Fetuin A (alpha 2-HS glycoprotein) was reduced about 34%, alpha-1-Antitrypsin was reduced about 34% in CIS and about 13% in RRMS and Apolipoprotein A1 was increased about 37% only in CIS. In addition, using ELISA techniques further validation of the potential candidate biomarkers were performed. First results confirm that the candidate biomarkers may useful to predict disease subtype and relapse activity.

Conclusions: These data suggest that proteomic research of CSF may provide a useful tool for the identification of putative MS-associated biomarkers and surrogate endpoints.