Oxidative Stress and Neurobiology of Demyelination

Despite a large amount of research which aims at defining the pathophysiology of human demyelination (i.e., multiple sclerosis), etiological bases of disease have been unknown so far. The point of intersection of all assumed etiological factors, which are mainly based upon immunological cascades, is neuroinflammation. The precise definition of the place and role of all pathogenetic factors in the occurrence and development of the disease is of crucial importance for understanding the clinical nature and for finding more effective therapeutic options. There are few studies whose results give more precise data about the role and the importance of other factors in neuroinflammation, besides immunological ones, with regard to clinical and paraclinical correlates of the disease. The review integrates results found in previously performed studies which have evaluated oxidative stress participation in early and late neuroinflammation. The largest number of studies indicates that the use of antioxidants affects the change of neuroinflammation course under experimental conditions, which is reflected in the reduction of the severity and the total reversibility in clinical presentation of the disease, the faster achieving of remission, and the delayed and slow course of neuroinflammation. Therapies based on the knowledge of redox biology targeting free radical generation hold great promise in modulation of the neuroinflammation and its clinical presentations.

Erythrocytes' antioxidative capacity as a potential marker of oxidative stress intensity in neuroinflammation

The study is designed to assess the oxidative stress intensity in erythrocytes obtained from patients in different clinical phenotypes of neuroinflammation, defined as clinically isolated syndrome (CIS) and relapsing-remitting multiple sclerosis (RRMS). Advanced oxidation protein products (AOPP), malondialdehyde (MDA) and superoxide dismutase (SOD) activity were measured and compared with patients' clinical severity (expanded disability status scale-EDSS), radiological findings (gadolinium enhancement lesion volume-Gd+) and disease duration (DD). AOPP, MDA values and SOD activity were significantly higher in both study patients than in the control group (p < 0.05). While AOPP and MDA approached higher values in RRMS, compared to the CIS group (p > 0.05, p < 0.05, respectively), SOD activity showed higher values in CIS than in RRMS patients (p < 0.05). Both study patients with higher EDSS, higher number of total radiological lesions and longer DD, had higher AOPP and MDA content (p < 0.05, p > 0.05). SOD activity was lower in both study patients with higher EDSS, higher number of total radiological lesions and longer DD (p < 0.05, p > 0.05). There were positive correlations between AOPP and DD and EDSS in CIS patients (p < 0.01), and MDA levels and DD, EDSS and Gd+ in CIS, as well as with EDSS in RRMS patients (p < 0.01). There were negative correlations between SOD activity and DD and EDSS in both study patients (p < 0.01), as well as, between SOD activity and Gd+ in CIS patients (p < 0.01). The measured erythrocytes' biomarkers might represent one of the important biomarkers for the evaluation of the oxidative status of neuroinflammation and disease severity, especially in its early phase, defined as CIS.

Chronic kidney disease predicts impaired membrane microviscosity of red blood cells in hypertensive and normotensive subjects

Current evidence indicates that abnormalities in physical properties of the cell membranes may be strongly linked to hypertension and other circulatory disorders. Recent studies have shown that chronic kidney disease (CKD) might be a risk factor for cardiovascular and cerebrovascular outcomes. The purpose of the present study was to examine the possible relationship between kidney function and membrane fluidity (a reciprocal value of membrane microviscosity) of red blood cells (RBCs) in hypertensive and normotensive subjects using an electron spin resonance (ESR) and spin-labeling method. The order parameter (S) for the ESR spin-label agent (5-nitroxide stearate) in RBC membranes was significantly higher in hypertensive subjects than in normotensive subjects, indicating that membrane fluidity was decreased in hypertension. The order parameter (S) of RBCs was inversely correlated with estimated glomerular filtration rate (eGFR), suggesting that a decreased eGFR value might be associated with reduced membrane fluidity of RBCs. Multivariate regression analysis also demonstrated that, after adjustment for general risk factors, eGFR might be a significant predictor of membrane fluidity of RBCs. The reduced levels of both membrane fluidity of RBCs and eGFR were associated with increased plasma 8-iso-prostaglandin F2α (an index of oxidative stress) and decreased plasma nitric oxide (NO)-metabolites, suggesting that kidney function could be a determinant of membrane microviscosity of RBCs, at least in part, via oxidative stress- and NO-dependent mechanisms. The ESR study suggests that CKD might have a close correlation with impaired rheologic behavior of RBCs and microcirculatory disorders in hypertensive subjects.