Are antioxidant parameters in serum altered in patients with relapsing-remitting multiple sclerosis treated with II-line immunomodulatory therapy?

New Insights into Oxidative Stress and Inflammatory Response in Neurodegenerative Diseases

Oxidative stress (OS) and inflammation are two important and well-studied pathological hallmarks of neurodegenerative diseases (NDDs). Due to elevated oxygen consumption, the high presence of easily oxidizable polyunsaturated fatty acids and the weak antioxidant defenses, the brain is particularly vulnerable to oxidative injury. Uncertainty exists over whether these deficits contribute to the development of NDDs or are solely a consequence of neuronal degeneration. Furthermore, these two pathological hallmarks are linked, and it is known that OS can affect the inflammatory response. In this review, we will overview the last findings about these two pathways in the principal NDDs. Moreover, we will focus more in depth on amyotrophic lateral sclerosis (ALS) to understand how anti-inflammatory and antioxidants drugs have been used for the treatment of this still incurable motor neuron (MN) disease. Finally, we will analyze the principal past and actual clinical trials and the future perspectives in the study of these two pathological mechanisms.

Evaluation of antioxidant parameters of multiple sclerosis patients' serum according to the disease course

INTRODUCTION

Multiple sclerosis (MS) is a chronic, demyelinating disease of the central nervous system. Its clinical courses are clinically isolated syndrome (CIS), relapsing remitting (RRMS), secondary progressive (SPMS), and primary progressive (PPMS). The differentiation of MS types is crucial for adequate treatment.

OBJECTIVES

To evaluate antioxidant parameters of MS patients' serum according to MS type.

MATERIALS AND METHODS

The study included 84 patients diagnosed with MS. The study group was divided into three subgroups corresponding to MS courses RRMS, SPMS, and PPMS. Sulfhydryl groups (SH), ceruloplasmin (CER), and superoxide dismutase (SOD) and its isoforms were identified in study participants' sera.

RESULTS

CuZnSOD levels were significantly higher in SPMS patients than in PPMS patients, but there was no difference between SMPS and treatment-naive PPMS patients. MnSOD activity was significantly lower in SPMS patients than in PPMS patients. Our results show that SH levels were decreased in SPMS patients compared with RRMS patients, but this difference was significant only for male participants. SH concentration was reversely correlated with age, BMI, disease duration, EDSS, and in smoking patients with pack-years. CER serum levels waere elevated in SPMS patients compared with RRMS patients, but this difference was significant only for male participants. Our results show correlation between CER and EDSS levels.

CONCLUSION

Oxidative stress plays a limited role in all disease stages, particularly in smokers as a confounding factor.

Neurocognitive impairment in multiple sclerosis and its association with thiol-disulfide homeostasis and ischemia-modified albumin

This study aimed to assess the possible association between cognitive impairment and two important biochemical biomarkers of oxidative stress, thiol-disulfide homeostasis (TDH), and ischemia-modified albumin (IMA) in patients with multiple sclerosis (MS). This study included 85 patients with MS (38 treatment-naïve relapsing-remitting MS (RRMS), 31 RRMS on fingolimod therapy, and 16 secondary progressive MS (SPMS)) and 33 healthy controls. Cognitive evaluation was carried out by applying the Brief International Cognitive Assessment for Multiple Sclerosis (BICAMS) test battery and the scores were adjusted for age and years of education. Plasma TDH was assessed using an automated method and plasma IMA levels were determined using the cobalt-albumin binding assay. Plasma native thiol and total thiol levels were significantly decreased in patients with SPMS when compared with the naïve patients and healthy controls. Cognitive impairment was detected in 47.4% of naïve patients, 64.5% of patients on fingolimod therapy, and 80% of patients with SPMS. Naïve patients or patients on fingolimod therapy who were cognitively impaired had significantly decreased levels of native thiol and total thiol compared to the cognitively normal patients. Logistic regression analysis revealed total thiol and native thiol to be significantly associated with cognitive impairment in naïve patients and patients on fingolimod therapy. Significant correlations were determined between BICAMS scores, TDH, IMA, clinical indices of disease severity (EDSS and MSSS), and magnetic resonance imaging parameters. This study has shown for the first time that plasma TDH parameters are associated with cognitive impairment in MS.

Decreased Cerebrospinal Fluid Antioxidative Capacity Is Related to Disease Severity and Progression in Early Multiple Sclerosis

Background: Oxidative stress-induced neuronal damage in multiple sclerosis (MS) results from an imbalance between toxic free radicals and counteracting antioxidants, i.e., antioxidative capacity (AOC). The relation of AOC to outcome measures in MS still remains inconclusive. We aimed to compare AOC in cerebrospinal fluid (CSF) and serum between early MS and controls and assess its correlation with clinical/radiological measures. Methods: We determined AOC (ability of CSF and serum of patients to inhibit 2,2′-azobis(2-amidinopropane) dihydrochloride-induced oxidation of dihydrorhodamine) in clinically isolated syndrome (CIS)/early relapsing-remitting MS (RRMS) (n = 55/11) and non-inflammatory neurological controls (n = 67). MS patients underwent clinical follow-up (median, 4.5; IQR, 5.2 years) and brain MRI at 3 T (baseline/follow-up n = 47/34; median time interval, 3.5; IQR, 2.1 years) to determine subclinical disease activity. Results: CSF AOC was differently regulated among CIS, RRMS and controls (p = 0.031) and lower in RRMS vs. CIS (p = 0.020). Lower CSF AOC correlated with physical disability (r = −0.365, p = 0.004) and risk for future relapses (exp(β) = 0.929, p = 0.033). No correlations with MRI metrics were found. Conclusion: Decreased CSF AOC was associated with increased disability and clinical disease activity in MS. While our finding cannot prove causation, they should prompt further investigations into the role of AOC in the evolution of MS.

Oxidative stress activity of fingolimod in multiple sclerosis

OBJECTIVE

Multiple sclerosis (MS) is a demyelinating chronic inflammatory disease of the central nervous system (CNS). Recent studies have shown that oxidative stress plays an important role in MS pathogenesis. This study aimed to investigate the relationship between total oxidative stress (TOS) and total antioxidant capacity (TAC), which were reported to be effective in the pathogenesis of MS, and therapeutic efficacy of fingolimod used in the treatment of MS.

MATERIALS AND METHODS

Serum TOS and total TAC levels of 25 patients with relapsing-remitting MS (RRMS) were measured before fingolimod treatment was initiated and in the third month of treatment and compared with those of 40 healthy individuals. Measurement of TOS activity was performed with TOS Assay Kit (Rel Assay Diagnostics, Turkey). Measurement of TAC activity was also performed with TAC Assay Kit (Rel Assay Diagnostics, Turkey).

RESULTS

A statistically significant increase was observed in the TOS levels measured before fingolimod treatment in the patient group compared to the control group. The TOS levels measured in the third month of the treatment were found to decrease significantly compared to the pre-treatment TOS levels. An increase was observed in TAC levels after the treatment; however, no significant difference was found between the groups in terms of TAC levels. There was a positive correlation between the pre- and post-treatment Expanded Disability Status Scale (EDSS) scores and TOS values whereas no significant correlation was observed between the pre- and post-treatment EDSS scores and TAC values.

CONCLUSION

The present study has revealed that fingolimod reduced oxidative stress. There was a positive correlation between the pre- and post-treatment EDSS and TOS values, which confirmed that there was a close correlation between the MS and oxidative stress. There are some limitations in this study. The small number of patients and the short follow-up times can be listed among these limitations. Our study does not contain a definitive answer to what is the mechanism of increased TOS in MS patients and how fingolimod reduces TOS levels. More detailed studies are needed on this subject.