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  • Title: Plasma ubiquitin-proteasome system profile in patients with multiple sclerosis: correlation with clinical features, neuroimaging, and treatment with interferon-beta-1b.
    Author: Minagar A, Ma W, Zhang X, Wang X, Zhang K, Alexander JS, Gonzalez-Toledo E, Albitar M.
    Journal: Neurol Res; 2012 Jul; 34(6):611-8. PubMed ID: 22709658.
    Abstract:
    OBJECTIVE: Interferon-beta-1b (IFN-beta-1b) reduces relapses in multiple sclerosis (MS) and improves magnetic resonance imaging (MRI) outcomes. Mechanism of action of IFN-beta-1b is only marginally understood. The roles and plasma levels of factors within the ubiquitin-proteasome system (UPS) and the plasma proteasome enzymatic activity of MS patients have not been explored. We hypothesized that pharmacologic double inhibition of the UPS by IFN-beta-1b occurs in MS patients and contributes to improvement of clinical course and reduction in MRI activity. METHODS: During a 6-month prospective study, we measured plasma proteasome and ubiquitin protein levels and the proteasome enzymatic activities in patients with MS pre- (n = 35) and post-treatment (n = 26) with IFN-beta-1b and 96 normal controls. The results were compared to clinical and brain MRI outcomes. RESULTS: Plasma levels of ubiquitin and proteasome enzymatic activities were elevated in MS patients before therapy with IFN-beta-1b as compared to normals (P < 0.01). Additionally, UPS enzymatic activities were increased in MS patients before treatment with IFN-beta-1b (P < 0.0001). Six months after treatment with IFN-beta-1b, plasma levels of proteasome and ubiquitin showed further elevation as compared to the pre-treatment values and normals. Treatment with IFN-beta-1b suppressed the enzymatic activity of plasma proteasome and such lowered level of enzymatic activity correlated with a decline in the number of post-contrast T1-weighted enhancing lesions. CONCLUSION: Since UPS is linked to protein degradation, it may contribute to the course of immune-mediated diseases such as MS, and pharmacologic inhibition of UPS through IFN-beta-1b therapy improves the clinical course of MS. Larger clinical trials are needed to confirm the results of this preliminary study.
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