RESUMO
UNLABELLED: Peroxynitrite (PN) has been implicated in multiple sclerosis (MS) and its animal model experimental allergic encephalomyelitis. Uric acid (UA) serum levels of MS patients, a natural scavenger of PN, were found lowered in some recent studies. OBJECTIVE/PURPOSE: The objective of our study was to correlate UA serum levels and several clinical parameters of MS. We also tried to investigate serum UA changes during treatment with immunomodulating or immunosuppressing drugs in the last 6 months. PATIENTS AND METHODS: We measured UA serum levels in 190 patients with MS and 58 age and gender matched patients with inflammatory (IND) and non-inflammatory diseases (NIND) studied as control groups. UA levels were correlated with clinical parameters as type of the disease, duration, disability, magnetic resonance imaging (MRI) activity and female gender. RESULTS: In the overall MS group, patients were found to have significantly lower mean serum uric acid levels compared with the IND (p = 0.0029) and the NIND group (p < 0.0001). UA serum concentrations were not inversely correlated with duration of the disease (p = 0.87), with disability as assessed by Expanded Disability Status Scale (EDSS) score (p = 0.67) and MRI activity (p = 0.36). Treatment with immunomodulating or immunosuppressing drugs had no influence in UA levels (p = 0.85). Patients with Clinically Isolated Syndromes (CIS) were found to have significantly lower UA concentrations compared with IND and NIND patients (p = 0.009 and <0.001, respectively). CONCLUSIONS: Our findings suggest that lower serum UA levels in MS patients may represent a primary, constitutive loss of protection against nitric oxide and the development of CNS inflammation and tissue damage may not have a direct effect to UA serum levels. They also provide support that the earlier increase of UA serum levels might be beneficial in the future treatment of MS.