The patients with clinically isolated syndrome and relapsing remitting multiple sclerosis show different levels of advanced protein oxidation products and total thiol content in plasma and CSF

• We investigated AOPP and total SH groups in plasma and CSF of CIS and RRMS patients.
• The obtained results were compared regarding EDSS and MRI patients’ features.
• Plasma and CSF AOPP and SH group levels were higher in CIS than RRMS.
• There were a linear correlation between examined biomarkers and EDSS.
• No correlations were observed between AOPP and SH levels and MRI patients features.

Advanced oxidation protein products (AOPP) and total thiol (SH) groups levels in plasma and CSF were studied in a cohort of 50 clinically isolated syndrome (CIS) and 57 relapsing remittent multiple sclerosis (RRMS) patients related to 20 control group (CG) patients’ values. The obtained results were compared regarding patients demographic, biochemical, clinical (EDSS) and MRI features (total T2 weighted lesions number and Gd enhancement lesion volume).Plasma and CSF AOPP levels in CIS and RRMS patients were higher than those in CG, while SH groups showed lower values compared to CG (p < 0.05). Both parameters were higher in CIS than in RRMS patients (p < 0.05). Related to EDSS median range, all patients were divided into those with slight or mild and those with severe clinical presentation. AOPP and SH group changes were more pronounced in both, CIS and RRMS patients with higher, compared to those with lower EDSS (p < 0.05). AOPP, SH group levels and EDSS positive correlations were observed in both study groups (p < 0.01). Both parameters showed the same approach regarding the median range of total T2 weighted lesions and Gd enhancement lesion volume mean values (p < 0.05), but no correlation was found between AOPP and SH levels and these patients radiological characteristics (p > 0.01).The data support the fact that oxidative stress is always involved in CIS and RRMS pathophysiology, but not always as a disease determinant dependent on its intensity, which might be important for new therapeutic strategies based on antioxidant approach in those patients.