Oxidative modification of blood serum proteins in multiple sclerosis after interferon or mitoxantrone treatment

• Indices of oxidative protein damage are useful to evaluate oxidative stress in MS;
• The level of oxidative stress is higher in relapsing-remitting MS patients;
• Oxidative stress is higher in patients treated with mitoxantrone.

This study was aimed at (i) comparison of the usefulness of serum protein oxidation parameters for assessment of oxidative stress (OS) in multiple sclerosis (MS), and (ii) comparison of OS in MS patients subject to various therapies. Elevated glycophore level was noted in relapsing–remitting (RRMS) patients without treatment and patients treated with interferons β1a and β1b (10.33 ± 3.27, 8.02 ± 2.22 and 8.56 ± 2.45 vs control 5.27 ± 0.73 fluorescence units (FU)/mg protein). Advanced oxidation protein products (295 ± 135 vs 83 ± 65 nmol/mg protein), carbonyl groups (3.68 ± 1.44 nmol/mg protein vs 2.03 ± 0.23 nmol/mg protein), kynurenine (7.71 ± 0.1.67 vs 5.5 ± 0.63 FU/mg protein) and N′-formylkynurenine (7.69 ± 0.7 vs 4.97 ± 0.59 FU/mg protein) levels were increased, while thioredoxin level was decreased in RRMS patients without treatment (5.03 ± 2.18 vs 10.83 ± 2.75 ng/ml) with respect to control. The level of OS was higher in untreated RRMS patients and in SPMS patients treated with mitoxantrone than in patients treated with interferon.