Oxidative stress and its impact on neurons and glia in multiple sclerosis lesions

From Mouse to Human: Comparative Analysis between Grey and White Matter by Synchrotron-Fourier Transformed Infrared Microspectroscopy

Fourier Transform Infrared microspectroscopy (μFTIR) is a very useful method to analyze the biochemical properties of biological samples in situ. Many diseases affecting the central nervous system (CNS) have been studied using this method, to elucidate alterations in lipid oxidation or protein aggregation, among others. In this work, we describe in detail the characteristics between grey matter (GM) and white matter (WM) areas of the human brain by μFTIR, and we compare them with the mouse brain (strain C57BL/6), the most used animal model in neurological disorders. Our results show a clear different infrared profile between brain areas in the lipid region of both species. After applying a second derivative in the data, we established a 1.5 threshold value for the lipid/protein ratio to discriminate between GM and WM areas in non-pathological conditions. Furthermore, we demonstrated intrinsic differences of lipids and proteins by cerebral area. Lipids from GM present higher C=CH, C=O and CH₃ functional groups compared to WM in humans and mice. Regarding proteins, GM present lower Amide II amounts and higher intramolecular β-sheet structure amounts with respect to WM in both species. However, the presence of intermolecular β-sheet structures, which is related to β-aggregation, was only observed in the GM of some human individuals. The present study defines the relevant biochemical properties of non-pathological human and mouse brains by μFTIR as a benchmark for future studies involving CNS pathological samples.

Signatures of cell stress and altered bioenergetics in skin fibroblasts from patients with multiple sclerosis

Multiple sclerosis (MS) is a central nervous system inflammatory demyelinating disease and the most common cause of non-traumatic disability in young adults. Despite progress in the treatment of the active relapsing disease, therapeutic options targeting irreversible progressive decline remain limited. Studies using skin fibroblasts derived from patients with neurodegenerative disorders demonstrate that cell stress pathways and bioenergetics are altered when compared to healthy individuals. However, findings in MS skin fibroblasts are limited. Here, we collected skin fibroblasts from 24 healthy control individuals, 30 patients with MS, and ten with amyotrophic lateral sclerosis (ALS) to investigate altered cell stress profiles. We observed endoplasmic reticulum swelling in MS skin fibroblasts, and increased gene expression of cell stress markers including BIP, ATF4, CHOP, GRP94, P53, and P21. When challenged against hydrogen peroxide, MS skin fibroblasts had reduced resiliency compared to ALS and controls. Mitochondrial and glycolytic functions were perturbed in MS skin fibroblasts while exhibiting a significant increase in lactate production over ALS and controls. Our results suggest that MS skin fibroblasts have an underlying stress phenotype, which may be disease specific. Interrogating MS skin fibroblasts may provide patient specific molecular insights and aid in prognosis, diagnosis, and therapeutic testing enhancing individualized medicine.

Arbutin Improves Functional Recovery and Attenuates Glial Activation in Lysolecethin-Induced Demyelination Model in Rat Optic Chiasm

Neuroinflammation, glial activation, and oxidative injury are the main pathological mechanisms of demyelination in multiple sclerosis (MS). Arbutin, a natural polyphenol compound, possesses antioxidant, anti-inflammatory, and neuroprotective properties whose therapeutic potential has not been studied in the experimental animal models of MS. In the present study, the efficiency of arbutin on lysolecthin (LPC)-induced local demyelination model was investigated. Demyelination was induced by micro-injection of 2 μl LPC (1%) into the rat optic chiasm and the treated group received daily injection of arbutin (50 mg/kg, i.p) during 2 weeks. Visual-evoked potential (VEP) recordings were used to functionally assess the visual pathway. Gene expression analysis was done to evaluate the arbutin effect on the inflammatory, stress oxidative-related mediators, and myelin markers. The myelin-specific staining was performed to assess demyelination and GFAP staining as an astrocyte marker. We found that arbutin significantly reduced P1-latency of VEPs waves and demyelination at 7 and 14 days post-demyelination. Arbutin decreased inflammatory cytokines (IL-1B, IL-17, TNF-α) and iNOS mRNA expression level. In addition, the expression level of anti-inflammatory cytokine (IL-10) and antioxidant mediators (Nrf-2 and HO-1) was enhanced by arbutin treatment. Arbutin increased MBP and Olig2 expression levels in demyelination context. Finally, arbutin attenuated GFAP as an astrocyte marker. Finally, this study demonstrates that arbutin improves functional recovery and myelin repair in the demyelinated optic chiasm through attenuation of inflammation, astrocyte activation, and oxidative stress. These findings might open new promising avenues for treating demyelinating disorders such as multiple sclerosis. Graphical abstract.

Cadmium-Induced Oxidative Stress: Focus on the Central Nervous System

Cadmium (Cd), a category I human carcinogen, is a well-known widespread environmental pollutant. Chronic Cd exposure affects different organs and tissues, such as the central nervous system (CNS), and its deleterious effects can be linked to indirect reactive oxygen species (ROS) generation. Since Cd is predominantly present in +2 oxidation state, it can interplay with a plethora of channels and transporters in the cell membrane surface in order to enter the cells. Mitochondrial dysfunction, ROS production, glutathione depletion and lipid peroxidation are reviewed in order to better characterize the Cd-elicited molecular pathways. Furthermore, Cd effects on different CNS cell types have been highlighted to better elucidate its role in neurodegenerative disorders. Indeed, Cd can increase blood-brain barrier (BBB) permeability and promotes Cd entry that, in turn, stimulates pericytes in maintaining the BBB open. Once inside the CNS, Cd acts on glial cells (astrocytes, microglia, oligodendrocytes) triggering a pro-inflammatory cascade that accounts for the Cd deleterious effects and neurons inducing the destruction of synaptic branches.

Effects of Biotin on survival, ensheathment, and ATP production by oligodendrocyte lineage cells in vitro

Mechanisms implicated in disease progression in multiple sclerosis include continued oligodendrocyte (OL)/myelin injury and failure of myelin repair. Underlying causes include metabolic stress with resultant energy deficiency. Biotin is a cofactor for carboxylases involved in ATP production that impact myelin production by promoting fatty acid synthesis. Here, we investigate the effects of high dose Biotin (MD1003) on the functional properties of post-natal rat derived oligodendrocyte progenitor cells (OPCs). A2B5 positive OPCs were assessed using an in vitro injury assay, culturing cells in either DFM (DMEM/F12+N1) or “stress media” (no glucose (NG)-DMEM), with Biotin added over a range from 2.5 to 250 μg/ml, and cell viability determined after 24 hrs. Biotin reduced the increase in OPC cell death in the NG condition. In nanofiber myelination assays, biotin increased the percentage of ensheathing cells, the number of ensheathed segments per cell, and length of ensheathed segments. In dispersed cell culture, Biotin also significantly increased ATP production, assessed using a Seahorse bio-analyzer. For most assays, the positive effects of Biotin were observed at the higher end of the dose-response analysis. We conclude that Biotin, in vitro, protects OL lineage cells from metabolic injury, enhances myelin-like ensheathment, and is associated with increased ATP production.

Neuroprotective and neurotoxic outcomes of androgens and estrogens in an oxidative stress environment

BACKGROUND

The role of sex hormones on cellular function is unclear. Studies show androgens and estrogens are protective in the CNS, whereas other studies found no effects or damaging effects. Furthermore, sex differences have been observed in multiple oxidative stress-associated CNS disorders, such as Alzheimer's disease, depression, and Parkinson's disease. The goal of this study is to examine the relationship between sex hormones (i.e., androgens and estrogens) and oxidative stress on cell viability.

METHODS

N27 and PC12 neuronal and C6 glial phenotypic cell lines were used. N27 cells are female rat derived, whereas PC12 cells and C6 cells are male rat derived. These cells express estrogen receptors and the membrane-associated androgen receptor variant, AR45, but not the full-length androgen receptor. N27, PC12, and C6 cells were exposed to sex hormones either before or after an oxidative stressor to examine neuroprotective and neurotoxic properties, respectively. Estrogen receptor and androgen receptor inhibitors were used to determine the mechanisms mediating hormone-oxidative stress interactions on cell viability. Since the presence of AR45 in the human brain tissue was unknown, we examined the postmortem brain tissue from men and women for AR45 protein expression.

RESULTS

Neither androgens nor estrogens were protective against subsequent oxidative stress insults in glial cells. However, these hormones exhibited neuroprotective properties in neuronal N27 and PC12 cells via the estrogen receptor. Interestingly, a window of opportunity exists for sex hormone neuroprotection, wherein temporary hormone deprivation blocked neuroprotection by sex hormones. However, if sex hormones are applied following an oxidative stressor, they exacerbated oxidative stress-induced cell loss in neuronal and glial cells.

CONCLUSIONS

Sex hormone action on cell viability is dependent on the cellular environment. In healthy neuronal cells, sex hormones are protective against oxidative stress insults via the estrogen receptor, regardless of sex chromosome complement (XX, XY). However, in unhealthy (e.g., high oxidative stress) cells, sex hormones exacerbated oxidative stress-induced cell loss, regardless of cell type or sex chromosome complement. The non-genomic AR45 receptor, which is present in humans, mediated androgen's damaging effects, but it is unknown which receptor mediated estrogen's damaging effects. These differential effects of sex hormones that are dependent on the cellular environment, receptor profile, and cell type may mediate the observed sex differences in oxidative stress-associated CNS disorders.

High fat diet consumption results in mitochondrial dysfunction, oxidative stress, and oligodendrocyte loss in the central nervous system

Metabolic syndrome is a key risk factor and co-morbidity in multiple sclerosis (MS) and other neurological conditions, such that a better understanding of how a high fat diet contributes to oligodendrocyte loss and the capacity for myelin regeneration has the potential to highlight new treatment targets. Results demonstrate that modeling metabolic dysfunction in mice with chronic high fat diet (HFD) consumption promotes loss of oligodendrocyte progenitors across the brain and spinal cord. A number of transcriptomic and metabolomic changes in ER stress, mitochondrial dysfunction, and oxidative stress pathways in HFD-fed mouse spinal cords were also identified. Moreover, deficits in TCA cycle intermediates and mitochondrial respiration were observed in the chronic HFD spinal cord tissue. Oligodendrocytes are known to be particularly vulnerable to oxidative damage, and we observed increased markers of oxidative stress in both the brain and spinal cord of HFD-fed mice. We additionally identified that increased apoptotic cell death signaling is underway in oligodendrocytes from mice chronically fed a HFD. When cultured under high saturated fat conditions, oligodendrocytes decreased both mitochondrial function and differentiation. Overall, our findings show that HFD-related changes in metabolic regulators, decreased mitochondrial function, and oxidative stress contribute to a loss of myelinating cells. These studies identify HFD consumption as a key modifiable lifestyle factor for improved myelin integrity in the adult central nervous system and in addition new tractable metabolic targets for myelin protection and repair strategies.

Alterations of Transcription of Genes Coding Anti-oxidative and Mitochondria-Related Proteins in Amyloid β Toxicity: Relevance to Alzheimer's Disease

A growing body of evidence indicates that pathological forms of amyloid beta (Aβ) peptide contribute to neuronal degeneration and synaptic loss in Alzheimer's disease (AD). In this study, we investigated the impact of exogenous Aβ1-42 oligomers (AβO) and endogenously liberated Aβ peptides on transcription of genes for anti-oxidative and mitochondria-related proteins in cell lines (neuronal SH-SY5Y and microglial BV2) and in brain cortex of transgenic AD (Tg-AD) mice, respectively. Our results demonstrated significant AβO-evoked changes in transcription of genes in SH-SY5Y cells, where AβO enhanced expression of Sod1, Cat, mt-Nd1, Bcl2, and attenuated Sirt5, Sod2 and Sdha. In BV2 line, AβO increased the level of mRNA for Sod2, Dnm1l, Bcl2, and decreased for Gpx4, Sirt1, Sirt3, mt-Nd1, Sdha and Mfn2. Then, AβO enhanced free radicals level and impaired mitochondrial membrane potential only in SH-SY5Y cells, but reduced viability of both cell types. Inhibitor of poly(ADP-ribose)polymerase-1 and activator of sirtuin-1 more efficiently enhanced viability of SH-SY5Y than BV2 affected by AβO. Analysis of brain cortex of Tg-AD mice confirmed significant downregulation of Sirt1, Mfn1 and mt-Nd1 and upregulation of Dnm1l. In human AD brain, changes of microRNA pattern (miRNA-9, miRNA-34a, miRNA-146a and miRNA-155) seem to be responsible for decrease in Sirt1 expression. Overall, our results demonstrated a diverse response of neuronal and microglial cells to AβO toxicity. Alterations of genes encoding Sirt1, Mfn1 and Drp1 in an experimental model of AD suggest that modulation of mitochondria dynamics and Sirt1, including miRNA strategy, may be crucial for improvement of AD therapy.

New insights in the mechanisms of impaired redox signaling and its interplay with inflammation and immunity in multiple sclerosis

Multiple sclerosis (MS) is an autoimmune neurological disease characterized by chronic inflammation of the central nervous system (CNS), leading to demyelination and axonal damage and resulting in a range of physical, mental or even psychiatric symptoms. Key role of oxidative stress (OS) in the pathogenesis of MS has been suggested, as indicated by the biochemical analysis of cerebrospinal fluid and blood samples, tissue homogenates, and animal models of multiple sclerosis. OS causes demyelination and neurodegeneration directly, by oxidation of lipids, proteins and DNA but also indirectly, by inducing a dysregulation of the immunity and favoring the state of pro-inflammatory response. In this review, we discuss the interrelated mechanisms of the impaired redox signaling, of which the most important are inflammation-induced production of free radicals by activated immune cells and growth factors, release of iron from myelin sheath during demyelination and mitochondrial dysfunction and consequent energy failure and impaired oxidative phosphorylation. Review also provides an overview of the interplay between inflammation, immunity and OS in MS. Finally, this review also points out new potential targets in MS regarding attenuation of OS and inflammatory response in MS.

Nutritional ketosis as an intervention to relieve astrogliosis: Possible therapeutic applications in the treatment of neurodegenerative and neuroprogressive disorders

Nutritional ketosis, induced via either the classical ketogenic diet or the use of emulsified medium-chain triglycerides, is an established treatment for pharmaceutical resistant epilepsy in children and more recently in adults. In addition, the use of oral ketogenic compounds, fractionated coconut oil, very low carbohydrate intake, or ketone monoester supplementation has been reported to be potentially helpful in mild cognitive impairment, Parkinson’s disease, schizophrenia, bipolar disorder, and autistic spectrum disorder. In these and other neurodegenerative and neuroprogressive disorders, there are detrimental effects of oxidative stress, mitochondrial dysfunction, and neuroinflammation on neuronal function. However, they also adversely impact on neurone–glia interactions, disrupting the role of microglia and astrocytes in central nervous system (CNS) homeostasis. Astrocytes are the main site of CNS fatty acid oxidation; the resulting ketone bodies constitute an important source of oxidative fuel for neurones in an environment of glucose restriction. Importantly, the lactate shuttle between astrocytes and neurones is dependent on glycogenolysis and glycolysis, resulting from the fact that the astrocytic filopodia responsible for lactate release are too narrow to accommodate mitochondria. The entry into the CNS of ketone bodies and fatty acids, as a result of nutritional ketosis, has effects on the astrocytic glutamate–glutamine cycle, glutamate synthase activity, and on the function of vesicular glutamate transporters, EAAT, Na⁺, K⁺-ATPase, K_ir4.1, aquaporin-4, Cx34 and K_ATP channels, as well as on astrogliosis. These mechanisms are detailed and it is suggested that they would tend to mitigate the changes seen in many neurodegenerative and neuroprogressive disorders. Hence, it is hypothesized that nutritional ketosis may have therapeutic applications in such disorders.

Siponimod therapy implicates Th17 cells in a preclinical model of subpial cortical injury

Subpial demyelination is a specific hallmark of multiple sclerosis and a correlate of disease progression. Although the mechanism(s) that mediate pathogenesis in the subpial compartment remain unclear, it has been speculated that inflammation in the overlying meninges may be associated with subpial injury. Here we show that adoptive transfer of proteolipid protein-primed Th17 cells into SJL/J recipient mice induces subpial demyelination associated with microglial/macrophage activation, disruption of the glial limitans, and evidence of an oxidative stress response. This pathology was topologically associated with foci of immune cells in the meninges and occurred in the absence of measurable anti-myelin oligodendrocyte glycoprotein IgM or IgG antibodies. To test the role of brain-infiltrating leukocytes on subpial injury, we modulated sphingosine 1-phosphate (S1P) receptor1,5 activity with BAF312 (siponimod) treatment. Administration of BAF312, even after adoptively transferred T cells had entered the brain, significantly ameliorated clinical experimental autoimmune encephalomyelitis and diminished subpial pathology, concomitant with a selective reduction in the capacity of transferred T cells to make Th17 cytokines. We conclude that sustained subpial cortical injury is associated with the capacity for brain-resident T cells to produce Th17 cytokines, and this pathological process occurs in an S1P receptor1,5-dependent manner.

Autophagy in Astrocytes and its Implications in Neurodegeneration

Autophagy is a major degradation pathway where double-membrane vesicles called autophagosomes deliver cytoplasmic content to the lysosome. Increasing evidence suggests that autophagy dysfunction contributes to the pathogenesis of neurodegenerative diseases. In addition, misfolded proteins that accumulate in these diseases and constitute a common pathological hallmark are substrates for autophagic degradation. Astrocytes, a major type of glial cells, are emerging as a critical component in most neurodegenerative diseases. This review will summarize the recent efforts to investigate the role that autophagy plays in astrocytes in the context of neurodegenerative diseases. While the field has mostly focused on the implications of autophagy in neurons, autophagy may also be involved in the clearance of disease-related proteins in astrocytes as well as in maintaining astrocyte function, which could impact the cell autonomous and non-cell autonomous contribution of astrocytes to neurodegeneration.

Regulation of microglial TMEM119 and P2RY12 immunoreactivity in multiple sclerosis white and grey matter lesions is dependent on their inflammatory environment

Multiple Sclerosis (MS) is the most common cause of acquired neurological disability in young adults, pathologically characterized by leukocyte infiltration of the central nervous system, demyelination of the white and grey matter, and subsequent axonal loss. Microglia are proposed to play a role in MS lesion formation, however previous literature has not been able to distinguish infiltrated macrophages from microglia. Therefore, in this study we utilize the microglia-specific, homeostatic markers TMEM119 and P2RY12 to characterize their immunoreactivity in MS grey matter lesions in comparison to white matter lesions. Furthermore, we assessed the immunological status of the white and grey matter lesions, as well as the responsivity of human white and grey matter derived microglia to inflammatory mediators. We are the first to show that white and grey matter lesions in post-mortem human material differ in their immunoreactivity for the homeostatic microglia-specific markers TMEM119 and P2RY12. In particular, whereas immunoreactivity for TMEM119 and P2RY12 is decreased in the center of WMLs, immunoreactivity for both markers is not altered in GMLs. Based on data from post-mortem human microglia cultures, treated with IL-4 or IFNγ+LPS and on  counts of CD3⁺ or CD20⁺ lymphocytes in lesions, we show that downregulation of TMEM119 and P2RY12  immunoreactivity in MS lesions corresponds with the presence of lymphocytes and lymphocyte-derived cytokines within the parenchyma but not in  the meninges. Furthermore, the presence of TMEM119⁺ and partly P2RY12⁺ microglia in pre-active lesions as well as in  the rim of active white and grey matter lesions, in addition to TMEM119⁺ and P2RY12⁺ rod-like microglia in subpial grey matter lesions suggest that blocking the entrance of lymphocytes into the CNS of MS patients may not interfere with all possible effects of TMEM119⁺ and P2RY12⁺ microglia in both white and grey matter MS lesions.

Biotin attenuation of oxidative stress, mitochondrial dysfunction, lipid metabolism alteration and 7β-hydroxycholesterol-induced cell death in 158N murine oligodendrocytes

Mitochondrial dysfunction and oxidative stress are involved in neurodegenerative diseases associated with an enhancement of lipid peroxidation products such as 7β-hydroxycholesterol (7β-OHC). It is, therefore, important to study the ability of 7β-OHC to trigger mitochondrial defects, oxidative stress, metabolic dysfunctions and cell death, which are hallmarks of neurodegeneration, and to identify cytoprotective molecules. The effects of biotin were evaluated on 158N murine oligodendrocytes, which are myelin synthesizing cells, exposed to 7β-OHC (50 µM) with or without biotin (10 and 100 nM) or α-tocopherol (positive control of cytoprotection). The effects of biotin on 7β-OHC activities were determined using different criteria: cell adhesion; plasma membrane integrity; redox status. The impact on mitochondria was characterized by the measurement of transmembrane mitochondrial potential (ΔΨm), reactive oxygen species (ROS) overproduction, mitochondrial mass, quantification of cardiolipins and organic acids. Sterols and fatty acids were also quantified. Cell death (apoptosis, autophagy) was characterized by the enumeration of apoptotic cells, caspase-3 activation, identification of autophagic vesicles, and activation of LC3-I into LC3-II. Biotin attenuates 7β-OHC-induced cytotoxicity: loss of cell adhesion was reduced; antioxidant activities were normalized. ROS overproduction, protein and lipid oxidation products were decreased. Biotin partially restores mitochondrial functions: attenuation of the loss of ΔΨm; reduced levels of mitochondrial O₂^•- overproduction; normalization of cardiolipins and organic acid levels. Biotin also normalizes cholesterol and fatty acid synthesis, and prevents apoptosis and autophagy (oxiapoptophagy). Our data support that biotin, which prevents oligodendrocytes damages, could be useful in the treatment of neurodegeneration and demyelination.

Suppression of the Peripheral Immune System Limits the Central Immune Response Following Cuprizone-Feeding: Relevance to Modelling Multiple Sclerosis

Cuprizone (CPZ) preferentially affects oligodendrocytes (OLG), resulting in demyelination. To investigate whether central oligodendrocytosis and gliosis triggered an adaptive immune response, the impact of combining a standard (0.2%) or low (0.1%) dose of ingested CPZ with disruption of the blood brain barrier (BBB), using pertussis toxin (PT), was assessed in mice. 0.2% CPZ(±PT) for 5 weeks produced oligodendrocytosis, demyelination and gliosis plus marked splenic atrophy (37%) and reduced levels of CD4 (44%) and CD8 (61%). Conversely, 0.1% CPZ(±PT) produced a similar oligodendrocytosis, demyelination and gliosis but a smaller reduction in splenic CD4 (11%) and CD8 (14%) levels and no splenic atrophy. Long-term feeding of 0.1% CPZ(±PT) for 12 weeks produced similar reductions in CD4 (27%) and CD8 (43%), as well as splenic atrophy (33%), as seen with 0.2% CPZ(±PT) for 5 weeks. Collectively, these results suggest that 0.1% CPZ for 5 weeks may be a more promising model to study the ‘inside-out’ theory of Multiple Sclerosis (MS). However, neither CD4 nor CD8 were detected in the brain in CPZ±PT groups, indicating that CPZ-mediated suppression of peripheral immune organs is a major impediment to studying the ‘inside-out’ role of the adaptive immune system in this model over long time periods. Notably, CPZ(±PT)-feeding induced changes in the brain proteome related to the suppression of immune function, cellular metabolism, synaptic function and cellular structure/organization, indicating that demyelinating conditions, such as MS, can be initiated in the absence of adaptive immune system involvement.

Effects of crocin in reducing DNA damage, inflammation, and oxidative stress in multiple sclerosis patients: A double-blind, randomized, and placebo-controlled trial

Multiple sclerosis (MS) is an autoimmune disease in which the immune system attacks the nerve cells, resulting in neurological disorders. Oxidative stress, free radicals, and neuritis have important roles in MS pathogenesis. Here, we aim to evaluate the effect of crocin on inflammatory markers, oxidative damage, and deoxyribonucleic acid (DNA) damage in the blood of patients with MS. A total of 40 patients were divided into two groups, drug and placebo-treated groups, using random assignment. Participants of the intervention and control groups received two crocin capsules or placebo per day for 28 days, respectively. Findings revealed a significant decrease in the level of important pathogenic factors in MS, including lipid peroxidation, DNA damage, tumor necrosis factor-alpha, and interleukin 17 as well as a significant increase in the total antioxidant capacity in the serum of patients treated with crocin compared with the placebo group. Our results suggest the beneficial and therapeutic effects of crocin in MS.

Central Nervous System Remyelination: Roles of Glia and Innate Immune Cells

In diseases such as multiple sclerosis (MS), inflammation can injure the myelin sheath that surrounds axons, a process known as demyelination. The spontaneous regeneration of myelin, called remyelination, is associated with restoration of function and prevention of axonal degeneration. Boosting remyelination with therapeutic intervention is a promising new approach that is currently being tested in several clinical trials. The endogenous regulation of remyelination is highly dependent on the immune response. In this review article, we highlight the cell biology of remyelination and its regulation by innate immune cells. For the purpose of this review, we discuss the roles of microglia, and also astrocytes and oligodendrocyte progenitor cells (OPCs) as they are being increasingly recognized to have immune cell functions.

Myelin Disturbances Produced by Sub-Toxic Concentration of Heavy Metals: The Role of Oligodendrocyte Dysfunction

Evidence has been accumulated demonstrating that heavy metals may accumulate in various organs, leading to tissue damage and toxic effects in mammals. In particular, the Central Nervous System (CNS) seems to be particularly vulnerable to cumulative concentrations of heavy metals, though the pathophysiological mechanisms is still to be clarified. In particular, the potential role of oligodendrocyte dysfunction and myelin production after exposure to subtoxic concentration I confirmed. It is ok of heavy metals is to be better assessed. Here we investigated on the effect of sub-toxic concentration of several essential (Cu^{2 +}, Cr^{3 +}, Ni^{2 +}, Co²⁺) and non-essential (Pb^{2 +}, Cd²⁺, Al³⁺) heavy metals on human oligodendrocyte MO3.13 and human neuronal SHSY5Y cell lines (grown individually or in co-culture). MO3.13 cells are an immortal human–human hybrid cell line with the phenotypic characteristics of primary oligodendrocytes but following the differentiation assume the morphological and biochemical features of mature oligodendrocytes. For this reason, we decided to use differentiated MO3.13 cell line. In particular, exposure of both cell lines to heavy metals produced a reduced cell viability of co-cultured cell lines compared to cells grown separately. This effect was more pronounced in neurons that were more sensitive to metals than oligodendrocytes when the cells were grown in co-culture. On the other hand, a significant reduction of lipid component in cells occurred after their exposure to heavy metals, an effect accompanied by substantial reduction of the main protein that makes up myelin (MBP) in co-cultured cells. Finally, the effect of heavy metals in oligodendrocytes were associated to imbalanced intracellular calcium ion concentration as measured through the fluorescent Rhod-2 probe, thus confirming that heavy metals, even used at subtoxic concentrations, lead to dysfunctional oligodendrocytes. In conclusion, our data show, for the first time, that sub-toxic concentrations of several heavy metals lead to dysfunctional oligodendrocytes, an effect highlighted when these cells are co-cultured with neurons. The pathophysiological mechanism(s) underlying this effect is to be better clarified. However, imbalanced intracellular calcium ion regulation, altered lipid formation and, finally, imbalanced myelin formation seem to play a major role in early stages of heavy metal-related oligodendrocyte dysfunction.

Upregulating Nrf2 in the RVLM ameliorates sympatho-excitation in mice with chronic heart failure

Nuclear factor E2-related factor 2 (Nrf2) is a key transcription factor that maintains redox homeostasis by governing a broad array of antioxidant genes in response to oxidant stress. We hypothesized that overexpression of Nrf2 in the rostral ventrolateral medulla (RVLM) ameliorates sympatho-excitation in mice with coronary artery ligation-induced chronic heart failure (CHF). To address this, we overexpressed Nrf2 in the RVLM using an HIV-CamKIIa-Nrf2 lenti virus in C57BL/6 mice. In addition, we used a Lenti-Cre virus in Keap1^flox/flox mice to upregulate Nrf2 non-selectively in the RVLM. Arterial blood pressure (AP), heart rate (HR), and renal sympathetic nerve activity (RSNA) were recorded under conscious and anesthetized conditions, respectively. Protein expression was assayed using western blotting and immunofluorescence staining. We found that (1) Nrf2 and two target proteins, NQO1 and HO-1 in the RVLM were significantly lower in CHF compared to Sham mice. Nrf2 viral transfection of the RVLM upregulated Nrf2 protein. (2) Urinary NE excretion in CHF mice was markedly attenuated following Nrf2 upregulation (812 ± 133 vs 1120 ± 271 ng/24hr mean. ±SE, *p < 0.05, n = 8/group). (3) In the conscious state, CHF mice overexpressing Nrf2 exhibited an enhancement in spontaneous baroreflex gain and in phenylephrine-induced baroreflex control of HR. (4) Acute experiments under anesthetisa revealed a significant decrease in basal RSNA (44.0 ± 6.5 vs 64.7 ± 8.3% of Max. *P < 0.05 n = 8/group) and enhancement in baroreflex sensitivity (Maximal gain -1.8 ± 0.3 vs 1.1 ± 0.2 of mmHg. **p < 0.01. n = 6/group) in CHF mice that were virally transfected with Nrf2 compared with CHF mice transfected with Lenti-GFP. Finally, Lenti-Cre viral overexpression of Nrf2 in Keap1^flox/flox mice reduced Keap1 protein and increased Nrf2, NQO1, and HO-1 in the RVLM of Sham and CHF mice. CHF-Cre mice exhibited a significant decrease in baseline RSNA and plasma NE concentration (8.9 ± 1.1 vs 12.7 ± 0.9 ng/mL *P < 0.05 n = 6/group) as compared with CHF-GFP mice. Based on the above data, we conclude that upregulating Nrf2 selectively in the RVLM attenuates sympatho-excitation in CHF mice. Nrf2 may be an important central target for autonomic modulation in cardiovascular disease and during stress.

A Review of Various Antioxidant Compounds and their Potential Utility as Complementary Therapy in Multiple Sclerosis

Multiple sclerosis (MS) is a complex disease of the central nervous system (CNS). The etiology of this multifactorial disease has not been clearly defined. Conventional medical treatment of MS has progressed, but is still based on symptomatic treatment. One of the key factors in the pathogenesis of MS is oxidative stress, enhancing inflammation and neurodegeneration. In MS, both reactive oxygen and nitrogen species are formed in the CNS mainly by activated macrophages and microglia structures, which can lead to demyelination and axon disruption. The course of MS is associated with the secretion of many inflammatory and oxidative stress mediators, including cytokines (IL-1b, IL-6, IL-17, TNF-α, INF-γ) and chemokines (MIP-1a, MCP-1, IP10). The early stage of MS (RRMS) lasts about 10 years, and is dominated by inflammatory processes, whereas the chronic stage is associated with neurodegenerative axon and neuron loss. Since oxidative damage has been known to be involved in inflammatory and autoimmune-mediated processes, antioxidant therapy could contribute to the reduction or even prevention of the progression of MS. Further research is needed in order to establish new aims for novel treatment and provide possible benefits to MS patients. The present review examines the roles of oxidative stress and non-pharmacological anti-oxidative therapies in MS.

Effect of High-Intensity Exercise on Multiple Sclerosis Function and Phosphorous Magnetic Resonance Spectroscopy Outcomes

PURPOSE

We determined if a high-intensity aerobic exercise program would be safe, improve expected fitness and clinical outcomes, and alter exploratory phosphorous magnetic resonance spectroscopy (P MRS) outcomes in persons with multiple sclerosis (PwMS).

METHODS

This open-label prospective pilot study compared two cohorts of ambulatory PwMS matched for age, sex and V˙O2max. Cohorts underwent 8 wk of high-intensity aerobic exercise (MS-Ex, n = 10) or guided stretching (MS-Ctr, n = 7). Aerobic exercise consisted of four 30-min sessions per week while maintaining ≥70% maximal HR. Changes in cardiorespiratory fitness, clinical outcomes, and P MRS of tibialis anterior (TA) muscle and brain were compared. Cross-sectional P MRS comparisons were made between all MS participants and a separate matched healthy control population.

RESULTS

The MS-Ex cohort achieved target increases in V˙O2max (mean, +12.7%; P = <0.001, between-group improvement, P = 0.03). One participant was withdrawn for exercise-induced syncope. The MS-Ex cohort had within-group improvements in fat mass (-5.8%; P = 0.04), lean muscle mass (+2.6%; P = 0.02), Symbol Digit Modalities Test (+15.1%; P = 0.04), and cognitive subscore of the Modified Fatigue Impact Scale (-26%; P = 0.03), whereas only the physical subscore of the Modified Fatigue Impact Scale improved in MS-Ctr (-16.1%; P = 0.007). P MRS revealed significant within-group increases in MS-Ex participants in TA rate constant of phosphocreatine (PCr) recovery (+31.5%; P = 0.03) and adenosine triphosphate/PCr (+3.2%; P = 0.01), and near significant between-group increases in TA PCr recovery rate constant (P = 0.05) but no significant changes in brain P MRS after exercise. Cross-sectional differences existed between MS and healthy control brain PCr/inorganic phosphate (4.61 ± 0.44, 3.93 ± 0.19; P = 0.0019).

CONCLUSIONS

High-intensity aerobic exercise in PwMS improved expected cardiorespiratory and clinical outcomes but provoked one serious adverse event. The P MRS may serve to explore underlying mechanisms by which aerobic exercise exerts cerebral benefits.

The role of iron and myelin in orientation dependent R2* of white matter

Brain myelin and iron content are important parameters in neurodegenerative diseases such as multiple sclerosis (MS). Both myelin and iron content influence the brain's R₂^* relaxation rate. However, their quantification based on R₂^* maps requires a realistic tissue model that can be fitted to the measured data. In structures with low myelin content, such as deep gray matter, R₂^* shows a linear increase with increasing iron content. In white matter, R₂^* is not only affected by iron and myelin but also by the orientation of the myelinated axons with respect to the external magnetic field. Here, we propose a numerical model which incorporates iron and myelin, as well as fibre orientation, to simulate R₂^* decay in white matter. Applying our model to fibre orientation-dependent in vivo R₂^* data, we are able to determine a unique solution of myelin and iron content in global white matter. We determine an averaged myelin volume fraction of 16.02 ± 2.07% in non-lesional white matter of patients with MS, 17.32 ± 2.20% in matched healthy controls, and 18.19 ± 2.98% in healthy siblings of patients with MS. Averaged iron content was 35.6 ± 8.9 mg/kg tissue in patients, 43.1 ± 8.3 mg/kg in controls, and 47.8 ± 8.2 mg/kg in siblings. All differences in iron content between groups were significant, while the difference in myelin content between MS patients and the siblings of MS patients was significant. In conclusion, we demonstrate that a model that combines myelin-induced orientation-dependent and iron-induced orientation-independent components is able to fit in vivo R₂^* data.

Hypoglycemia causes dysregulation of Neuregulin 1, ErbB receptors, Ki67 in cerebellum and brainstem during diabetes: Implications in motor function

Hypoglycemia induced brain injury poses a major setback to optimal blood glucose regulation during diabetes. It causes irreversible injury in several brain regions culminating in improper function. Neuregulin 1 and ErbB receptors are involved in regeneration during adulthood as well as in glucose homeostasis. We intended to understand the influence of extreme discrepancies in glycemic levels on Neuregulin 1, ErbB receptor subtypes and Ki67 expression in relation to motor deficits as a consequence of cellular dysfunction/degeneration in the cerebellum and brainstem during diabetes. Elevated oxidative stress and compromised antioxidant system havocs cerebellum and brainstem related function. Cellular alteration of Purkinje neurons in the cerebellum and presence of axonal spheroids in the brainstem are suggestive of impairment to neural circuits involved in motor function. Down regulation of Neuregulin 1, ErbB 2, ErbB 3, ErbB 4 and Ki67 expression observed during diabetes and hypoglycemia may critically cause regenerative deficiency in cerebellum. The coincident up regulation of Neuregulin 1, ErbB 2, ErbB 3 and ErbB 4 in brainstem during diabetes is an attempt to maintain regenerative homeostasis to ensure its function. However, hypoglycemic insults results in down regulation of Neuregulin 1, ErbB 4 expression that severely compromises their role in brainstem. Grid walking test confirmed motor impairment during diabetes that showed further deterioration due to hypoglycemic stress. Thus altered expression of Neuregulin 1, ErbB receptor subtypes and Ki67 during diabetes and hypoglycemia contributes to reduced cellular proliferation and deficits in motor function.

Identification of an iron-responsive subtype in two children diagnosed with relapsing-remitting multiple sclerosis using whole exome sequencing

BACKGROUND

Multiple sclerosis is a disorder related to demyelination of axons. Iron is an essential cofactor in myelin synthesis. Previously, we described two children (males of mixed ancestry) with relapsing-remitting multiple sclerosis (RRMS) where long-term remission was achieved by regular iron supplementation. A genetic defect in iron metabolism was postulated, suggesting that more advanced genetic studies could shed new light on disease pathophysiology related to iron.

METHODS

Whole exome sequencing (WES) was performed to identify causal pathways. Blood tests were performed over a 10 year period to monitor the long-term effect of a supplementation regimen. Clinical wellbeing was assessed quarterly by a pediatric neurologist and regular feedback was obtained from the schoolteachers.

RESULTS

WES revealed gene variants involved in iron absorption and transport, in the transmembrane protease, serine 6 (TMPRSS6) and transferrin (TF) genes; multiple genetic variants in CUBN, which encodes cubilin (a receptor involved in the absorption of vitamin B12 as well as the reabsorption of transferrin-bound iron and vitamin D in the kidneys); SLC25A37 (involved in iron transport into mitochondria) and CD163 (a scavenger receptor involved in hemorrhage resolution). Variants were also found in COQ3, involved with synthesis of Coenzyme Q10 in mitochondria. Neither of the children had the HLA-DRB1*1501 allele associated with increased genetic risk for MS, suggesting that the genetic contribution of iron-related genetic variants may be instrumental in childhood MS. In both children the RRMS has remained stable without activity over the last 10 years since initiation of nutritional supplementation and maintenance of normal iron levels, confirming the role of iron deficiency in disease pathogenesis in these patients.

CONCLUSION

Our findings highlight the potential value of WES to identify heritable risk factors that could affect the reabsorption of transferrin-bound iron in the kidneys causing sustained iron loss, together with inhibition of vitamin B12 absorption and vitamin D reabsorption (CUBN) and iron transport into mitochondria (SLC25A37) as the sole site of heme synthesis. This supports a model for RRMS in children with an apparent iron-deficient biochemical subtype of MS, with oligodendrocyte cell death and impaired myelination possibly caused by deficits of energy- and antioxidant capacity in mitochondria.

Caffeine Modulates Cadmium-Induced Oxidative Stress, Neuroinflammation, and Cognitive Impairments by Regulating Nrf-2/HO-1 In Vivo and In Vitro

Cadmium (Cd), a nonbiodegradable heavy metal and one of the most neurotoxic environmental and industrial pollutants, promotes disturbances in major organs and tissues following both acute and chronic exposure. In this study, we assessed the neuroprotective potential of caffeine (30 mg/kg) against Cd (5 mg/kg)-induced oxidative stress-mediated neuroinflammation, neuronal apoptosis, and cognitive deficits in male C57BL/6N mice in vivo and in HT-22 and BV-2 cell lines in vitro. Interestingly, our findings indicate that caffeine markedly reduced reactive oxygen species (ROS) and lipid peroxidation (LPO) levels and enhanced the expression of nuclear factor-2 erythroid-2 (Nrf-2) and hemeoxygenase-1 (HO-1), which act as endogenous antioxidant regulators. Also, 8-dihydro-8-oxoguanine (8-OXO-G) expression was considerably reduced in the caffeine-treated group as compared to the Cd-treated group. Similarly, caffeine ameliorated Cd-mediated glial activation by reducing the expression of glial fibrillary acidic protein (GFAP), ionized calcium-binding adapter molecule 1 (Iba-1), and other inflammatory mediators in the cortical and hippocampal regions of the mouse brain. Moreover, caffeine markedly attenuated Cd-induced neuronal loss, synaptic dysfunction, and learning and cognitive deficits. Of note, nuclear factor-2 erythroid-2 (Nrf-2) gene silencing and nuclear factor-κB (NF-κB) inhibition studies revealed that caffeine exerted neuroprotection via regulation of Nrf-2- and NF-κB-dependent mechanisms in the HT-22 and BV-2 cell lines, respectively. On the whole, these findings reveal that caffeine rescues Cd-induced oxidative stress-mediated neuroinflammation, neurodegeneration, and memory impairment. The present study suggests that caffeine might be a potential antioxidant and neuroprotective agent against Cd-induced neurodegeneration.

Relationship of Iron Metabolism and Short-Term Cuprizone Treatment of C57BL/6 Mice

One of the models to investigate the distinct mechanisms contributing to neurodegeneration in multiple sclerosis is based on cuprizone (CZ) intoxication. CZ is toxic to mature oligodendrocytes and produces demyelination within the central nervous system but does not cause direct neuronal damage. The CZ model is suitable for better understanding the molecular mechanism of de- and remyelination processes of oligodendrocytes. CZ is a copper chelating agent and it also affects the iron metabolism in brain and liver tissues. To determine the early effect of CZ treatment on iron homeostasis regulation, cytosolic and mitochondrial iron storage, as well as some lipid metabolism genes, we investigated the expression of respective iron homeostasis and lipid metabolism genes of the corpus callosum (CC) and the liver after short-term CZ administration. In the present study C57BL/6 male mice aged four weeks were fed with standard rodent food premixed with 0.2 w/w% CZ for two or eight days. The major findings of our experiments are that short-term CZ treatment causes significant changes in iron metabolism regulation as well as in the expression of myelin and lipid synthesis-related genes, even before apparent demyelination occurs. Both in the CC and the liver the iron uptake, utilization and storage are modified, though not always the same way or to the same extent in the two organs. Understanding the role of iron in short-term and long-term CZ intoxication could provide a partial explanation of the discrepant signs of acute and chronic MS. These could contribute to understanding the development of multiple sclerosis and might provide a possible drug target.

Ameliorative effect of supercritical fluid extract of Chrysanthemum indicum Linnén against D-galactose induced brain and liver injury in senescent mice via suppression of oxidative stress, inflammation and apoptosis

ETHNOPHARMACOLOGICAL RELEVANCE

Chrysanthemum indicum Linne (C. indicum), a healthy food and folk medicine in China for thousands of years, has been reported to exert heat-clearing and detoxifying effects and extensively applied to treat various symptoms such as inflammation diseases, hepatitis and headache.

AIM OF THIS STUDY

The purpose of the present study was to investigate the protective effect of the supercritical carbon dioxide fluid extract from flowers and buds of C. indicum (CI_SCFE) on D-galactose-induced brain and liver damage during aging process and to illuminate the underlying mechanisms.

MATERIALS AND METHODS

Mice were orally administrated with CI_SCFE (100, 150 and 300 mg/kg) after injection with D-galactose. 24 h after the last administration, the blood samples, whole brain and liver tissues were collected for biochemical analysis, histological examination and western blot analysis. The body weight, spleen and thymus indexes, alanine transaminase (ALT), aspartate transaminase (AST), total antioxidant capacity (T-AOC), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), malondialdehyde (MDA) in brain and liver, interleukin-1β (IL-1β), interleukin-6 (IL-6), and necrosis factor-α (TNF-α) were detected. Besides, the expressions of Bax, Bcl-2 and cleaved caspase-3 were determined by western blot assay.

RESULTS

The results indicated that CI_SCFE effectively increased the suppressed body weight, attenuated the decline of thymus and spleen indexes, and reduced the elevated levels of ALT and AST induced by D-gal. Furthermore, CI_SCFE might notably alleviate D-gal-induced abnormal alterations in structure and function of brain and liver dose-dependently via renewing normal antioxidant enzymes activities (SOD, CAT, GSH-Px), reducing MDA accumulation, decreasing inflammatory cytokines productions (IL-1β, IL-6, TNF-α), as well as attenuating the increase of Bax/Bcl-2 ratio and cleaved caspase-3 activation in the liver and brain.

CONCLUSIONS

Taken together, our present results suggested that CI_SCFE treatment could effectively mitigate the D-gal-induced hepatic and cerebral injury, and the underlying mechanism might be tightly related to the decreased oxidative stress, inflammation and apoptosis, indicating CI_SCFE might be an alternative and promising agent for the treatment of aging and age-associated brain and liver diseases.

Inhibition of myeloperoxidase by N-acetyl lysyltyrosylcysteine amide reduces experimental autoimmune encephalomyelitis-induced injury and promotes oligodendrocyte regeneration and neurogenesis in a murine model of progressive multiple sclerosis

It is known that oxidative stress produced by proinflammatory myeloid cells plays an important role in demyelination and neuronal injury in progressive multiple sclerosis (MS). Myeloperoxidase (MPO) is a pro-oxidative enzyme released from myeloid cells during inflammation. It has been shown that MPO-dependent oxidative stress plays important roles in inducing tissue injury in many inflammatory diseases. In this report, we treated NOD experimental autoimmune encephalomyelitis (EAE) mice, a murine model of progressive MS, with N-acetyl lysyltyrosylcysteine amide (KYC), a novel specific MPO inhibitor. Our data showed that KYC treatment not only attenuated MPO-mediated oxidative stress but also reduced demyelination and axonal injury in NOD EAE mice. More importantly, we found that KYC treatment increased oligodendrocyte regeneration and neurogenesis in NOD EAE mice. Taken together, our data suggests that targeting MPO should be a good therapeutic approach for reducing oxidative injury and preserving neuronal function in progressive MS patients.

Animal Weight Is an Important Variable for Reliable Cuprizone-Induced Demyelination

An elegant model to study mechanisms operant during oligodendrocyte degeneration and subsequent demyelination is the cuprizone model. In that model, mice are intoxicated with the copper chelation agent cuprizone which results in early oligodendrocyte stress, oligodendrocyte apoptosis, and, finally, demyelination. Here, we systematically investigated to what extent the animals' weight at the beginning of the cuprizone intoxication period is critical for the reproducibility of the cuprizone-induced pathology. We can demonstrate that a negative correlation exists between the two variables "extent of cuprizone-induced demyelination" and "starting weight." Demyelination and microglia activation were more severe in low weight compared to heavy weight mice. These findings are highly relevant for the experimental design using the cuprizone model.

On the Neurobiological Role of Oxidative Stress in Alcohol-Induced Impulsive, Aggressive and Suicidal Behavior

Objectives: Alcohol abuse is known to result in behavioral impairments (such as increased impulsivity, aggressive, and suicidal behavior), but the neurobiological basis for these behavioral impairments remains unknown. The objective of this review is to propose a neurobiological basis for alcohol-induced aggression, impulsivity, and suicidal behavior. Methods: Search was done by accessing PubMed/Medline, EBSCO, and PsycINFO databases. The search string used was "(Alcohol OR Alcoholism* OR Alcohol Abuse) AND (Behavior* OR Behavioral Impairment or Disorder) AND (Oxidative Stress OR Reactive Oxygen Species)." The electronic databases were searched for titles or abstracts containing these terms in all published articles between January 1, 1960, and May 31, 2019. The search was limited to studies published in English and other languages involving both animal and human subjects. Articles selected included randomized clinical trials (RCTs), observational studies, meta-analyses, and both systemic and narrative reviews, providing both quantitative and qualitative information with a measure of alcohol abuse or alcoholism as an outcome. Exclusion criteria were unpublished data of any form, including conference proceedings and dissertation. New key terms were identified (new term included: "Antioxidants, Neurotransmitters, Dopamine, Serotonin, GABA, Glutamate. Aggression, Impulsivity, Suicidal Behavior, hippocampus, prefrontal cortex, limbic system, psychiatric disorders, PTSD, Anxiety, Depression. These new terms were searched with Alcohol or Alcoholism or Alcohol Abuse and Oxidative Stress separately resulting in the identification of over 3000 articles. 196 were included in this article. Results: Multiple lines of evidence indicate that oxidative stress (OS) plays a critical underlying role in alcohol toxicity and behavioral impairments. Conclusions/Importance: People diagnosed with PTSD, anxiety disorder, depression, and those with a personality high in psychoticism as measured by the P Scale of the Eysenck Personality Questionnaire, with comorbid alcohol abuse or alcohol use disorder (AUD), may display increased impulsivity, aggression, and suicidal behavior because of the potentiating effect of alcohol-induced OS on their elevated brain oxidative status. Antioxidant therapy should be an integral part of acute alcohol intoxication and AUD treatment. Further research is necessary to fully understand the relationship between OS and alcohol-induced behavioral impairments.

Microglia in Central Nervous System Inflammation and Multiple Sclerosis Pathology

Microglia are the resident macrophages of the central nervous system (CNS). They have important physiological functions in maintaining tissue homeostasis but also contribute to CNS pathology. Microglia respond to changes in the microenvironment, and the resulting reactive phenotype can be very diverse, with both neuroinflammatory and neuroprotective properties, illustrating the plasticity of these cells. Recent progress in understanding the autoimmune neuroinflammatory disease multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis suggests major roles for microglia in the disease, which have drastically changed our view on the function of microglia in MS.

Astrocytes and Aging

By 2050, the aging population is predicted to expand by over 100%. Considering this rapid growth, and the additional strain it will place on healthcare resources because of age-related impairments, it is vital that researchers gain a deeper understanding of the cellular interactions that occur with normal aging. A variety of mammalian cell types have been shown to become compromised with age, each with a unique potential to contribute to disease formation in the aging body. Astrocytes represent the largest group of glial cells and are responsible for a variety of essential functions in the healthy central nervous system (CNS). Like other cell types, aging can cause a loss of normal function in astrocytes which reduces their ability to properly maintain a healthy CNS environment, negatively alters their interactions with neighboring cells, and contribute to the heightened inflammatory state characteristic of aging. The goal of this review article is to consolidate the knowledge and research to date regarding the role of astrocytes in aging. In specific, this review article will focus on the morphology and molecular profile of aged astrocytes, the consequence of astrocyte dysfunction on homeostatic functions during aging, and the role of astrocytes in age-related neurodegenerative diseases.

Involvement of Mitochondria in Neurodegeneration in Multiple Sclerosis

Functional disruption and neuronal loss followed by progressive dysfunction of the nervous system underlies the pathogenesis of numerous disorders defined as "neurodegenerative diseases". Multiple sclerosis, a chronic inflammatory demyelinating disease of the central nervous system resulting in serious neurological dysfunctions and disability, is one of the most common neurodegenerative diseases. Recent studies suggest that disturbances in mitochondrial functioning are key factors leading to neurodegeneration. In this review, we consider data on mitochondrial dysfunctions in multiple sclerosis, which were obtained both with patients and with animal models. The contemporary data indicate that the axonal degeneration in multiple sclerosis largely results from the activation of Ca2+-dependent proteases and from misbalance of ion homeostasis caused by energy deficiency. The genetic studies analyzing association of mitochondrial DNA polymorphic variants in multiple sclerosis suggest the participation of mitochondrial genome variability in the development of this disease, although questions of the involvement of individual genomic variants are far from being resolved.

Oxidative Stress in Patients with Drug Resistant Partial Complex Seizure

Oxidative stress (OS) has been implicated as a pathophysiological mechanism of drug-resistant epilepsy, but little is known about the relationship between OS markers and clinical parameters, such as the number of drugs, age onset of seizure and frequency of seizures per month. The current study’s aim was to evaluate several oxidative stress markers and antioxidants in 18 drug-resistant partial complex seizure (DRPCS) patients compared to a control group (age and sex matched), and the results were related to clinical variables. We examined malondialdehyde (MDA), advanced oxidation protein products (AOPP), advanced glycation end products (AGEs), nitric oxide (NO), uric acid, superoxide dismutase (SOD), glutathione, vitamin C, 4-hydroxy-2-nonenal (4-HNE) and nitrotyrosine (3-NT). All markers except 4-HNE and 3-NT were studied by spectrophotometry. The expressions of 4-HNE and 3-NT were evaluated by Western blot analysis. MDA levels in patients were significantly increased (p ≤ 0.0001) while AOPP levels were similar to the control group. AGEs, NO and uric acid concentrations were significantly decreased (p ≤ 0.004, p ≤ 0.005, p ≤ 0.0001, respectively). Expressions of 3-NT and 4-HNE were increased (p ≤ 0.005) similarly to SOD activity (p = 0.0001), whereas vitamin C was considerably diminished (p = 0.0001). Glutathione levels were similar to the control group. There was a positive correlation between NO and MDA with the number of drugs. The expression of 3-NT was positively related with the frequency of seizures per month. There was a negative relationship between MDA and age at onset of seizures, as well as vitamin C with seizure frequency/month. We detected an imbalance in the redox state in patients with DRCPS, supporting oxidative stress as a relevant mechanism in this pathology. Thus, it is apparent that some oxidant and antioxidant parameters are closely linked with clinical variables.

Fabricating PLGA microparticles with high loads of the small molecule antioxidant N-acetylcysteine that rescue oligodendrocyte progenitor cells from oxidative stress

Reactive oxygen species (ROS), encompassing all oxygen radical or non-radical oxidizing agents, play key roles in disease progression. Controlled delivery of antioxidants is therapeutically relevant in such oxidant-stressed environments. Encapsulating small hydrophilic molecules into hydrophobic polymer microparticles via traditional emulsion methods has long been a challenge due to rapid mass transport of small molecules out of particle pores. We have developed a simple alteration to the existing water-in-oil-in-water (W/O/W) drug encapsulation method that dramatically improves loading efficiency: doping external water phases with drug to mitigate drug diffusion out of the particle during fabrication. PLGA microparticles with diameters ranging from 0.6 to 0.9 micrometers were fabricated, encapsulating high loads of 0.6-0.9 µm diameter PLGA microparticles were fabricated, encapsulating high loads of the antioxidant N-acetylcysteine (NAC), and released active, ROS-scavenging NAC for up to 5 weeks. Encapsulation efficiencies, normalized to the theoretical load of traditional encapsulation without doping, ranged from 96% to 400%, indicating that NAC-loaded external water phases not only prevented drug loss due to diffusion, but also doped the particles with additional drug. Antioxidant-doped particles positively affected the metabolism of oligodendrocyte progenitor cells (OPCs) under H₂ O₂ -mediated oxidative stress when administered both before (protection) or after (rescue) injury. Antioxidant doped particles improved outcomes of OPCs experiencing multiple doses of H₂ O₂ by increasing the intracellular glutathione content and preserving cellular viability relative to the injury control. Furthermore, antioxidant-doped particles preserve cell number, number of process extensions, cytoskeletal morphology, and nuclear size of H₂ O₂ -stressed OPCs relative to the injury control. These NAC-doped particles have the potential to provide temporally-controlled antioxidant therapy in neurodegenerative disorders such as multiple sclerosis (MS) that are characterized by continuous oxidative stress.

Inflammation and mitochondrial dysfunction: A vicious circle in neurodegenerative disorders?

Experimental evidence supports an intricate association between inflammation and mitochondrial dysfunction as main contributors of neurological diseases. Inflammatory mediators produced by activated microglia and infiltrated immune cells trigger intracellular signalling cascades that can alter cellular mitochondrial metabolism. Cytokines, particularly tumor necrosis factor-alpha, impede mitochondrial oxidative phosphorylation and associated ATP production and instigate mitochondrial reactive oxygen species production. This culminates in mitochondrial membrane permeabilization, altered mitochondrial dynamics and might ultimately result in cell death. When severely injured mitochondria are not appropriately removed by mitophagy they can release their contents into the cytosol and extracellular environment and thereby amplify the inflammatory process. Here we provide a comprehensive overview on how inflammatory mediators impair mitochondrial metabolism and discuss how defective mitochondria can elicit and potentiate an inflammatory response.

Dietary habits; concentration of copper, zinc, and Cu-to-Zn ratio in serum and ability status of patients with relapsing-remitting multiple sclerosis

OBJECTIVE

Dietary habits and adequate intake of antioxidants in the diet-for example, copper (Cu) and zinc (Zn)-may be an environmental factor in the occurrence of multiple sclerosis (MS). The aim of this study was to estimate the influence of dietary habits on the concentration of Cu, Zn in the serum, and the effect of Cu-to-Zn ratio on the ability status of patients with relapsing-remitting MS.

METHODS

This was an observational case-control study that included 101 individuals with MS and 68 healthy individuals (controls). Food frequency questionnaires were used to collect dietary data. Serum concentrations of Cu and Zn were determined by the electrothermal and flame atomic absorption spectrometry method, respectively. The ratio of Cu to Zn was calculated and compared with the Expanded Disability Status Scale of patients.

RESULTS

The concentration of Zn was significantly lower in the serum of individuals with MS (0.776 ± 0.195 mg/L) than in the control group (0.992 ± 0.315 mg/L). The ratio of Cu to Zn was higher in the examined patients (1.347 ± 0.806) than in the healthy volunteers (1.012 ± 0.458). Lower ability status (P < 0.05) was revealed in patients with an abnormal ratio of Cu to Zn, particularly, in cerebellar function, pyramidal tracts, and emotional conditions. Selected dietary habits have a significant influence on Cu and Zn concentration in the serum of patients with MS.

CONCLUSIONS

Lower serum concentrations of Zn and higher ratio of Cu to Zn in patients with MS can suggest a relationship between MS and oxidative stress. Products that are a source of Zn should be included in the diet, which can improve the clinical condition of people with MS.

Chicoric Acid Ameliorates Lipopolysaccharide-Induced Oxidative Stress via Promoting the Keap1/Nrf2 Transcriptional Signaling Pathway in BV-2 Microglial Cells and Mouse Brain

As a major nutraceutical component of a typical Mediterranean vegetable chicory, chicoric acid (CA) has been well-documented due to its excellent antioxidant and antiobesity bioactivities. In the current study, the effects of CA on lipopolysaccharide (LPS)-stimulated oxidative stress in BV-2 microglia and C57BL/6J mice and the underlying molecular mechanisms were investigated. Results demonstrated that CA significantly reversed LPS-elicited cell viability decrease, mitochondrial dysfunction, activation of NFκB and MAPK stress pathways, and inflammation responses via balancing cellular redox status. Furthermore, molecular modeling study demonstrated that CA could insert into the pocket of Keap1 and up-regulated Nrf2 signaling and, thus, transcriptionally regulate downstream expressions of antioxidant enzymes including HO-1 and NQO-1 in both microglial cells and ip injection of LPS-treated mouse brain. These results suggested that CA attenuated LPS-induced oxidative stress via mediating Keap1/Nrf2 transcriptional pathways and downstream enzyme expressions, which indicated that CA has great potential as a nutritional preventive strategy in oxidative stress-related neuroinflammation.

Elevated cerebrospinal fluid uric acid during relapse of neuromyelitis optica spectrum disorders

INTRODUCTION

Previous studies have shown that serum uric acid (UA) modulates outcomes of neurological diseases, although little is known about cerebrospinal fluid (CSF) UA levels in neuromyelitis optica spectrum disorders (NMOSDs).

METHODS

Cerebrospinal fluid and serum UA levels were measured in samples from 68 patients, including NMOSDs during relapse (n = 38) and controls with noninflammatory and non-neurodegenerative diseases (CTLs, n = 30). Correlation analysis was performed between CSF UA and clinical characteristics, serum UA, and blood-brain barrier integrity in NMOSDs.

RESULTS

Cerebrospinal fluid UA levels in NMOSDs were significantly higher than in CTLs (p = .002), while serum UA differences between NMOSDs and CTLs were not statistically significant. In NMOSDs, CSF UA levels were significantly higher in patients with an impaired blood-brain barrier than in patients with an intact one (p < .001), and significantly higher in longer disease duration than in shorter disease duration patients (p = .002). CSF UA levels were also significantly higher in active patients upon MRI than in inactive patients (p < .001), and significantly higher in patients with brain lesions than without brain lesions (p = .024). CSF UA was significantly associated with the serum UA levels (r = .454, p = .002), disease duration (r = .383, p = .018), and blood-brain barrier index (r = .805, p < .001), but did not correlate with age, gender, annualized relapse rate, duration, or severity of NMOSD. Multiple regression analysis demonstrated that CSF UA was independent of the blood-brain barrier index (β = .765, p < .001) and serum UA levels (β = .01, p = .019) in NMOSDs.

CONCLUSIONS

Cerebrospinal fluid UA levels were elevated in NMOSD patients during relapse, and were likely modified by serum UA levels and blood-brain barrier integrity.

Chicoric acid supplementation ameliorates cognitive impairment induced by oxidative stress via promotion of antioxidant defense system

Illustration of effects of chicoric acid on neuroprotection againstd-gal-induced memory impairmentviainflammation and oxidative stress.

Role of Oligodendrocyte Dysfunction in Demyelination, Remyelination and Neurodegeneration in Multiple Sclerosis

Oligodendrocytes (OLs) are the myelinating cells of the central nervous system (CNS) during development and throughout adulthood. They result from a complex and well controlled process of activation, proliferation, migration and differentiation of oligodendrocyte progenitor cells (OPCs) from the germinative niches of the CNS. In multiple sclerosis (MS), the complex pathological process produces dysfunction and apoptosis of OLs leading to demyelination and neurodegeneration. This review attempts to describe the patterns of demyelination in MS, the steps involved in oligodendrogenesis and myelination in healthy CNS, the different pathways leading to OLs and myelin loss in MS, as well as principles involved in restoration of myelin sheaths. Environmental factors and their impact on OLs and pathological mechanisms of MS are also discussed. Finally, we will present evidence about the potential therapeutic targets in re-myelination processes that can be accessed in order to develop regenerative therapies for MS.

Interleukin-13 immune gene therapy prevents CNS inflammation and demyelination via alternative activation of microglia and macrophages

Detrimental inflammatory responses in the central nervous system are a hallmark of various brain injuries and diseases. With this study we provide evidence that lentiviral vector-mediated expression of the immune-modulating cytokine interleukin 13 (IL-13) induces an alternative activation program in both microglia and macrophages conferring protection against severe oligodendrocyte loss and demyelination in the cuprizone mouse model for multiple sclerosis (MS). First, IL-13 mediated modulation of cuprizone induced lesions was monitored using T₂ -weighted magnetic resonance imaging and magnetization transfer imaging, and further correlated with quantitative histological analyses for inflammatory cell influx, oligodendrocyte death, and demyelination. Second, following IL-13 immune gene therapy in cuprizone-treated eGFP⁺ bone marrow chimeric mice, we provide evidence that IL-13 directs the polarization of both brain-resident microglia and infiltrating macrophages towards an alternatively activated phenotype, thereby promoting the conversion of a pro-inflammatory environment toward an anti-inflammatory environment, as further evidenced by gene expression analyses. Finally, we show that IL-13 immune gene therapy is also able to limit lesion severity in a pre-existing inflammatory environment. In conclusion, these results highlight the potential of IL-13 to modulate microglia/macrophage responses and to improve disease outcome in a mouse model for MS. GLIA 2016;64:2181-2200.