The role of mitochondria in axonal degeneration and tissue repair in MS

Rapamycin alleviates mitochondrial dysfunction in anti-NMDAR encephalitis mice

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is one of the most prevalent forms of autoimmune encephalitis, characterized by a series of neurological and psychiatric symptoms, including cognitive impairment, seizures and psychosis. The underlying mechanism of anti-NMDAR encephalitis remains unclear. In the current study, the mouse model of anti-NMDAR encephalitis with active immunization was performed. We first uncovered excessive mitochondrial fission in the hippocampus and temporal cortex of anti-NMDAR encephalitis mice, indicated by elevated level of Phospho-DRP1 (Ser616) (p-Drp1-S616). Moreover, blockade of the autophagic flux was also demonstrated, leading to the accumulation of fragmented mitochondria, and elevated levels of mitochondrial reactive oxygen species (mtROS) and mitochondrial DNA (mtDNA) in anti-NMDAR encephalitis. More importantly, we found that the mTOR signaling pathway was overactivated, which could aggravate mitochondrial fission and inhibit autophagy, resulting in mitochondrial dysfunction. While rapamycin, the specific inhibitor of the mTOR signaling pathway, significantly alleviated mitochondrial dysfunction by inhibiting mitochondrial fission and enhancing autophagy. Levels of mtROS and mtDNA were markedly reduced after the treatment of rapamycin. In addition, rapamycin also significantly alleviated cognitive dysfunction and anxious behaviors found in anti-NMDAR encephalitis mice. Thus, our study reveals the vital role of mitochondrial dysfunction in pathological mechanism of anti-NMDAR encephalitis and lays a theoretical foundation for rapamycin to become a clinically targeted drug for anti-NMDAR encephalitis.

Positioning regulation of organelle network via Chinese microneedle

The organelle network is a key factor in the repair and regeneration of lesion. However, effectively intervening in the organelle network which has complex interaction mechanisms is challenging. In this study, on the basis of electromagnetic laws, we constructed a biomaterial-based physical/chemical restraint device. This device was designed to jointly constrain electrical and biological factors in a conductive screw-threaded microneedle (ST-needle) system, identifying dual positioning regulation of the organelle network. The unique physical properties of this system could accurately locate the lesion and restrict the current path to the lesion cells through electromagnetic laws, and dynamic Van der Waals forces were activated to release functionalized hydrogel microspheres. Subsequently, the mitochondria-endoplasmic reticulum (ER) complex was synergistically targeted by increasing mitochondrial ATP supply to the ER via electrical stimulation and by blocking calcium current from the ER to the mitochondria using microspheres, and then the life activity of the lesion cells was effectively restored.

A Phase 1b, Open-Label Study to Evaluate the Safety and Tolerability of the Putative Remyelinating Agent, Liothyronine, in Individuals with MS

Thyroid hormones are essential during developmental myelination and may play a direct role in remyelination and repair in the adult central nervous system by promoting the differentiation of oligodendrocyte precursor cells into mature oligodendrocytes. Since tri-iodothyronine (T3) is believed to mediate the majority of important thyroid hormone actions, liothyronine (synthetic T3) has the potential to induce reparative mechanisms and limit neurodegeneration in multiple sclerosis (MS). We completed a phase 1b clinical trial to determine the safety and tolerability of ascending doses of liothyronine in individuals with relapsing and progressive MS. A total of 20 people with MS were enrolled in this single-center trial of oral liothyronine. Eighteen participants completed the 24-week study. Our study cohort included mostly women (11/20), majority relapsing MS (12/20), mean age of 46, and baseline median EDSS of 3.5. Liothyronine was tolerated well without treatment-related severe/serious adverse events or evidence of disease activation/clinical deterioration. The most common adverse events included gastrointestinal distress and abnormal thyroid function tests. No clinical thyrotoxicosis occurred. Importantly, we did not observe a negative impact on secondary clinical outcome measures. The CSF proteomic changes suggest a biological effect of T3 treatment within the CNS. We noted changes primarily in proteins associated with immune cell function and angiogenesis. Liothyronine appeared safe and was well tolerated in people with MS. A larger clinical trial will help assess whether liothyronine can promote oligodendrogenesis and enhance remyelination in vivo, limit axonal degeneration, or improve function.

Immunomodulatory therapy with glatiramer acetate reduces endoplasmic reticulum stress and mitochondrial dysfunction in experimental autoimmune encephalomyelitis

Endoplasmic reticulum (ER) stress and mitochondrial dysfunction are found in lesions of multiple sclerosis (MS) and animal models of MS such as experimental autoimmune encephalomyelitis (EAE), and may contribute to the neuronal loss that underlies permanent impairment. We investigated whether glatiramer acetate (GA) can reduce these changes in the spinal cords of chronic EAE mice by using routine histology, immunostaining, and electron microscopy. EAE spinal cord tissue exhibited increased inflammation, demyelination, mitochondrial dysfunction, ER stress, downregulation of NAD+ dependent pathways, and increased neuronal death. GA reversed these pathological changes, suggesting that immunomodulating therapy can indirectly induce neuroprotective effects in the CNS by mediating ER stress.

Neuromyelitis Optica Spectrum Disorder: From Basic Research to Clinical Perspectives

Neuromyelitis optica spectrum disorder (NMOSD) is an inflammatory disease of the central nervous system characterized by relapses and autoimmunity caused by antibodies against the astrocyte water channel protein aquaporin-4. Over the past decade, there have been significant advances in the biologic knowledge of NMOSD, which resulted in the IDENTIFICATION of variable disease phenotypes, biomarkers, and complex inflammatory cascades involved in disease pathogenesis. Ongoing clinical trials are looking at new treatments targeting NMOSD relapses. This review aims to provide an update on recent studies regarding issues related to NMOSD, including the pathophysiology of the disease, the potential use of serum and cerebrospinal fluid cytokines as disease biomarkers, the clinical utilization of ocular coherence tomography, and the comparison of different animal models of NMOSD.

A Narrative Review on Axonal Neuroprotection in Multiple Sclerosis

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) resulting in demyelination and neurodegeneration. The therapeutic strategy is now largely based on reducing inflammation with immunosuppressive drugs. Unfortunately, when disease progression is observed, no drug offers neuroprotection apart from its anti-inflammatory effect. In this review, we explore current knowledge on the assessment of neurodegeneration in MS and look at putative targets that might prove useful in protecting the axon from degeneration. Among them, Bruton's tyrosine kinase inhibitors, anti-apoptotic and antioxidant agents, sex hormones, statins, channel blockers, growth factors, and molecules preventing glutamate excitotoxicity have already been studied. Some of them have reached phase III clinical trials and carry a great message of hope for our patients with MS.

Activated glia cells cause bioenergetic impairment of neurons that can be rescued by knock-down of the mitochondrial calcium uniporter

Neuroinflammation is a hallmark of various neurological disorders including autoimmune-, neurodegenerative and neuropsychiatric diseases. In neuroinflammation, activated microglia and astrocytes release soluble mediators such as cytokines, glutamate, and reactive oxygen species that negatively affect neuronal function and viability, and thus contribute to neurodegeneration during disease progression. Therefore, the development of neuroprotective strategies might be important in addition to treating inflammation in these diseases. Mitochondria are promising cellular targets for neuroprotective interventions: They are among the first structures affected in many neuroinflammatory diseases, with mitochondrial impairment ranging from impaired respiratory activity and reduced mitochondrial membrane potential to mitochondrial oxidation and fragmentation. Therefore, we developed a cell culture model that resembles an early state of inflammation-induced neuronal mitochondrial dysfunction preceding neuronal cell death, and can be used to test mito- and neuroprotective strategies. Rat primary cortical neurons were challenged with conditioned medium from mixed primary cultures of rat microglia and astrocytes that had been activated with lipopolysaccharide and ATP. When sublethal amounts of glia-conditioned medium were added to neurons for 24 h, mitochondrial membrane potential and ATP levels were decreased, whereas mitochondrial redox state remained unaffected. Effects on mitochondrial membrane potential and ATP levels were ameliorated by knock-down of the mitochondrial calcium uniporter in neurons. This study suggests that neuronal bioenergetic failure is an early event during neuroinflammation and it identifies the mitochondrial calcium uniporter as a candidate target for neuroprotection in this context.

B Cells in the CNS at Postmortem Are Associated With Worse Outcome and Cell Types in Multiple Sclerosis

BACKGROUND AND OBJECTIVES

To define the clinical and pathologic correlations of compartmentalized perivascular B cells in postmortem progressive multiple sclerosis (MS) brains.

METHODS

Brain slices were acquired from 11 people with secondary progressive (SP) MS, 5 people with primary progressive (PP) MS, and 4 controls. Brain slices were immunostained for B lymphocytes (CD20), T lymphocytes (CD3), cytotoxic T lymphocytes (CD8), neuronal neurofilaments (NF200), myelin (SMI94), macrophages/microglia (CD68 and IBA1), astrocytes (glial fibrillary acidic protein [GFAP]), and mitochondria (voltage-dependent anion channel and cytochrome c oxidase subunit 4). Differences in CD20 immunostaining intensity between disease groups and associations between CD20 immunostaining intensity and both clinical variables and other immunostaining intensities were explored with linear mixed regression models and Cox regression models, as appropriate.

RESULTS

CD20 immunostaining intensity was higher in PPMS (Coeff = 0.410; 95% confidence interval [CI] = 0.046, 0.774; p = 0.027) and SPMS (Coeff = 0.302; 95% CI = 0.020, 0.585; p = 0.036) compared with controls. CD20 immunostaining intensity was higher in cerebellar, spinal cord, and pyramidal onset (Coeff = 0.274; 95% CI = 0.039, 0.510; p = 0.022) compared with optic neuritis and sensory onset. Higher CD20 immunostaining intensity was associated with younger age at onset (hazard ratio [HR] = 1.033; 95% CI = 1.013, 1.053; p = 0.001), SP conversion (HR = 1.056; 95% CI = 1.022, 1.091; p = 0.001), wheelchair dependence (HR = 1.472; 95% CI = 1.108, 1.954; p = 0.008), and death (HR = 1.684; 95% CI = 1.238, 2.291; p = 0.001). Higher immunostaining intensity for CD20 was associated with higher immunostaining intensity for CD3 (Coeff = 0.114; 95% CI = 0.005, 0.224; p = 0.040), CD8 (Coeff = 0.275; 95% CI = 0.200, 0.350; p < 0.001), CD68 (Coeff = 0.084; 95% CI = 0.023, 0.144; p = 0.006), GFAP (Coeff = 0.002; 95% CI = 0.001, 0.004; p = 0.030), and damaged mitochondria (Coeff = 3.902; 95% CI = 0.891, 6.914; p = 0.011).

DISCUSSION

Perivascular B cells were associated with worse clinical outcomes and CNS-compartmentalized inflammation. Our findings further support the concept of targeting compartmentalized B-cell inflammation in progressive MS.

Conserved spinal cord bioenergetics in experimental autoimmune encephalomyelitis in C57BL6 mice, measured using phosphorescence oxygen analyzer

Background

We have previously reported that spinal cord respiration (cellular mitochondrial oxygen consumption) and ATP content are conserved in the studied model of experimental autoimmune encephalomyelitis (EAE), foreseeing a recovery of the diseased rats. This exemplary lesion of multiple sclerosis is used here to measure spinal cord bioenergetics in C57BL6 mice. Our hypothesis is that, despite the well-known focal axonal mitochondrial pathology, bioenergetics of the CNS is reasonably preserved in this disease.

Methods

EAE was induced with an immunodominant myelin oligodendrocyte glycoprotein epitope in complete Freund's adjuvant, appended by injections of pertussis toxin. A low- and high-dose of the encephalitogen, administered into base of tail or hind-flank, were investigated. Control mice received only the incomplete adjuvant into tail. Oxygen measurements were based on quenching the phosphorescence of Pd(II) meso-tetra (sulfophenyl) tetrabenzoporphyrin by molecular oxygen. Cellular ATP was measured using the luciferin/luciferase system.

Results

The kinetics of spinal cord oxygen consumption was zero-order (linear with time) and inhibited by cyanide, confirming oxygen was reduced by cytochrome oxidase. The rate of respiration (in μM O₂.min⁻¹.mg⁻¹; measured on Days 13–28) in control mice was (mean ± SD) 0.086 ± 0.024 (n = 8) and in immunized mice was 0.079 ± 0.020 (n = 15, P = 0.265, Mann-Whitney test). Consistently, cellular ATP (in μmol mg⁻¹ dry pellet weight; measured on Days 13–28) in control mice was 0.068 ± 0.079 (n = 11) and in immunized mice was 0.063 ± 0.061 (n = 24, P = 0.887, Mann-Whitney U test).

Conclusions

In vitro measurements of spinal cord bioenergetics show conservation of the mitochondrial function in mice with EAE. These results suggest the previously documented reduced mitochondrial electrochemical potential in this disease is alterable, and likely reflects the adverse events of neuroinflammation.

Possible Role of Butyrylcholinesterase in Fat Loss and Decreases in Inflammatory Levels in Patients with Multiple Sclerosis after Treatment with Epigallocatechin Gallate and Coconut Oil: A Pilot Study

(1) Background. Multiple sclerosis (MS) is characterised by the loss of muscle throughout the course of the disease, which in many cases is accompanied by obesity and related to inflammation. Nonetheless, consuming epigallocatechin gallate (EGCG) and ketone bodies (especially β-hydroxybutyrate (βHB)) produced after metabolising coconut oil, have exhibited anti-inflammatory effects and a decrease in body fat. In addition, butyrylcholinesterase (BuChE), seems to be related to the pathogenesis of the disease associated with inflammation, and serum concentrations have been related to lipid metabolism. Objective. The aim of the study was to determine the role of BuChE in the changes caused after treatment with EGCG and ketone bodies on the levels of body fat and inflammation state in MS patients. (2) Methods. A pilot study was conducted for 4 months with 51 MS patients who were randomly divided into an intervention group and a control group. The intervention group received 800 mg of EGCG and 60 mL of coconut oil, and the control group was prescribed a placebo. Fat percentage and concentrations of the butyrylcholinesterase enzyme (BuChE), paraoxonase 1 (PON1) activity, triglycerides, interleukin 6 (IL-6), albumin and βHB in serum were measured. (3) Results. The intervention group exhibited significant decreases in IL-6 and fat percentage and significant increases in BuChE, βHB, PON1, albumin and functional capacity (determined by the Expanded Disability Status Scale (EDSS)). On the other hand, the control group only exhibited a decrease in IL-6. After the intervention, BuChE was positively correlated with the activity of PON1, fat percentage and triglycerides in the intervention group, whereas these correlations were not observed in the control group (4). Conclusions. BuChE seems to have an important role in lipolytic activity and the inflammation state in MS patients, evidenced after administering EGCG and coconut oil as a βHB source.

Synaptic Dysfunction in Multiple Sclerosis: A Red Thread from Inflammation to Network Disconnection

Multiple sclerosis (MS) has been clinically considered a chronic inflammatory disease of the white matter; however, in the last decade growing evidence supported an important role of gray matter pathology as a major contributor of MS-related disability and the involvement of synaptic structures assumed a key role in the pathophysiology of the disease. Synaptic contacts are considered central units in the information flow, involved in synaptic transmission and plasticity, critical processes for the shaping and functioning of brain networks. During the course of MS, the immune system and its diffusible mediators interact with synaptic structures leading to changes in their structure and function, influencing brain network dynamics. The purpose of this review is to provide an overview of the existing literature on synaptic involvement during experimental and human MS, in order to understand the mechanisms by which synaptic failure eventually leads to brain networks alterations and contributes to disabling MS symptoms and disease progression.

Diffusely appearing white matter in multiple sclerosis: Insights from sodium (23Na) MRI

BACKGROUND

In multiple sclerosis (MS), magnetic resonance imaging (MRI) frequently shows ill-defined areas with intermediate signal intensity between the normal appearing white matter (NAWM) and focal T2-hyperintense lesions, termed "diffusely appearing white matter" (DAWM). Even though several advanced MRI techniques have shown the potential to detect and quantify subtle commonly not visible microscopic tissue changes, to date only a few advanced MRI studies investigated DAWM changes in a quantitative manner. The aim of this study was to detect and quantify tissue abnormalities in the DAWM in comparison to focal lesions and the NAWM in MS patients by sodium (²³Na) MRI.

METHODS

²³Na and conventional MRI were performed in 25 MS patients with DAWM (DAWM⁺) and in 25 sex- and age matched MS patients without DAWM (DAWM^-), as well as in ten healthy controls (HC). Mean total sodium concentrations (TSC) were quantified in the DAWM, NAWM, normal appearing grey matter (NAGM) and in focal MS lesions.

RESULTS

In MS DAWM⁺and DAWM^-, TSC values were increased in the NAGM (DAWM⁺: 44.61 ± 4.09 mM; DAWM^-: 45.37 ± 3.8 mM) and in the NAWM (DAWM⁺: 39.85 ± 3.89 mM; DAWM^-: 39.82 ± 4.25 mM) compared to normal grey and white matter in HC (GM 40.87 ± 3.25 mM, WM 35.9 ± 1.81 mM; p < 0.05 for all comparisons). Interestingly, the DAWM showed similar sodium concentrations (39.32 ± 4.59 mM) to the NAWM (39.85 ± 3.89 mM), whereas TSC values in T1 hypointense (46.53 ± 7.87 mM) and T1 isointense (41.99 ± 6.10 mM) lesions were significantly higher than in the DAWM (p < 0.001 and 0.017 respectively).

CONCLUSION

²³Na MRI is confirmed as a sensitive marker of even subtle tissue abnormalities. DAWM sodium levels are increased and comparable to the abnormalities in NAWM, suggesting pathological changes less severe than in focal lesions comparable to what is expected in the NAWM.

Anterior visual system imaging to investigate energy failure in multiple sclerosis

Mitochondrial failure and hypoxia are key contributors to multiple sclerosis pathophysiology. Importantly, improving mitochondrial function holds promise as a new therapeutic strategy in multiple sclerosis. Currently, studying mitochondrial changes in multiple sclerosis is hampered by a paucity of non-invasive techniques to investigate mitochondrial function of the CNS in vivo. It is against this backdrop that the anterior visual system provides new avenues for monitoring of mitochondrial changes. The retina and optic nerve are among the metabolically most active structures in the human body and are almost always affected to some degree in multiple sclerosis. Here, we provide an update on emerging technologies that have the potential to indirectly monitor changes of metabolism and mitochondrial function. We report on the promising work with optical coherence tomography, showing structural changes in outer retinal mitochondrial signal bands, and with optical coherence angiography, quantifying retinal perfusion at the microcapillary level. We show that adaptive optics scanning laser ophthalmoscopy can visualize live perfusion through microcapillaries and structural changes at the level of single photoreceptors and neurons. Advantages and limitations of these techniques are summarized with regard to future research into the pathology of the disease and as trial outcome measures.

Pathologic correlates of the magnetization transfer ratio in multiple sclerosis

OBJECTIVE

To identify pathologic correlates of magnetization transfer ratio (MTR) in multiple sclerosis (MS) in an MRI-pathology study.

METHODS

We acquired MTR maps at 3T from 16 fixed MS brains and 4 controls, and immunostained 100 tissue blocks for neuronal neurofilaments, myelin (SMI94), tissue macrophages (CD68), microglia (IBA1), B-lymphocytes, T-lymphocytes, cytotoxic T-lymphocytes, astrocytes (glial fibrillary acidic protein), and mitochondrial damage (COX4, VDAC). We defined regions of interest in lesions, normal-appearing white matter (NAWM), and cortical normal-appearing gray matter (NAGM). Associations between MTR and immunostaining intensities were explored using linear mixed-effects models (with cassettes nested within patients) and interaction terms (for differences between regions of interest and between cases and controls); a multivariate linear mixed-effects model identified the best pathologic correlates of MTR.

RESULTS

MTR was the lowest in white matter (WM) lesions (23.4 ± 9.4%) and the highest in NAWM (38.1 ± 8.7%). In MS brains, lower MTR was associated with lower immunostaining intensity for myelin (coefficient 0.31; 95% confidence interval [CI] 0.07-0.55), macrophages (coefficient 0.03; 95% CI 0.01-0.07), and astrocytes (coefficient 0.51; 95% CI 0.02-1.00), and with greater mitochondrial damage (coefficient 0.31; 95% CI 0.07-0.55). Based on interaction terms, MTR was more strongly associated with myelin in WM (coefficient 1.58; 95% CI 1.09-2.08) and gray matter (GM) lesions (coefficient 0.66; 95% CI 0.13-1.20), and with macrophages (coefficient 1.40; 95% CI 0.56-2.25), astrocytes (coefficient 2.66; 95% CI 1.31-4.01), and mitochondrial damage (coefficient -12.59; 95% CI -23.16 to -2.02) in MS brains than controls. In the multivariate model, myelin immunostaining intensity was the best correlate of MTR (coefficient 0.31; 95% CI 0.09-0.52; p = 0.004).

CONCLUSIONS

Myelin was the strongest correlate of MTR, especially in WM and cortical GM lesions, but additional correlates should be kept in mind when designing and interpreting MTR observational and experimental studies in MS.

Mitochondrial complex IV is lost in neurons in the cuprizone mouse model

BACKGROUND

Cuprizone administration in mice leads to oligodendrocyte death and demyelination. The effect is thought to reflect copper-chelation that leads to inhibition of complex IV of the mitochondrial respiratory chain. The effects this drug has on neurons are less well known.

OBJECTIVE

To investigate the toxic effects of cuprizone on mitochondria in neurons.

METHODS

Male c57Bl/6 mice were fed 0.2% cuprizone for up to 5 weeks. Cuprizone-fed and control mice were examined at week 1, 3, 5 and 4 weeks after cessation of cuprizone exposure. The brain was examined for myelin, complex I, complex IV and for COX/SDH activities. Mitochondrial-DNA was investigated for deletions and copy number variation.

RESULTS

We found decreased levels of complex IV in the cerebellar Purkinje neurons of mice exposed to cuprizone. This decrease was not related to a general decrease in mitochondrial volume or mass, as there were no differences in the levels of complex I or TOMM20.

CONCLUSION

Neurons are affected by cuprizone-treatment. Whether this mitochondrial dysfunction acts as a subclinical trigger for demyelination and the long-term axonal degeneration that proceeds after cuprizone treatment stops remains unclear.

Coenzyme Q10 supplementation reduces peripheral oxidative stress and inflammation in interferon-β1a-treated multiple sclerosis

Background:

Oxidative stress is a driver of multiple sclerosis (MS) pathology. We evaluated the effect of coenzyme Q10 (CoQ10) on laboratory markers of oxidative stress and inflammation, and on MS clinical severity.

Methods:

We included 60 relapsing–remitting patients with MS treated with interferon beta1a 44μg (IFN-β1a) with CoQ10 for 3 months, and with IFN-β1a 44μg alone for 3 more months (in an open-label crossover design). At baseline and at the 3 and 6-month visits, we measured markers of scavenging activity, oxidative damage and inflammation in the peripheral blood, and collected data on disease severity.

Results:

After 3 months, CoQ10 supplementation was associated with improved scavenging activity (as mediated by uric acid), reduced intracellular reactive oxygen species production, reduced oxidative DNA damage, and a shift towards a more anti-inflammatory milieu in the peripheral blood [with higher interleukin (IL)-4 and IL-13, and lower eotaxin, granulocyte-macrophage colony-stimulating factor (GM-CSF), hepatocyte growth factor (HGF), interferon (IFN)-γ, IL-1α, IL-2R, IL-9, IL-17F, macrophage inflammatory proteins (MIP)-1α, regulated on activation-normal T cell expressed and secreted (RANTES), tumor necrosis factor (TNF)-α, and vascular endothelial growth factor (VEGF). Also, CoQ10 supplementation was associated with lower Expanded Disability Status Scale, fatigue severity scale, Beck’s depression inventory, and the visual analogue scale for pain.

Conclusions:

CoQ10 supplementation improved scavenging activity, reduced oxidative damage, and induced a shift towards a more anti-inflammatory milieu, in the peripheral blood of relapsing–remitting MS patients treated with 44μg IFN-β1a 44μg. A possible clinical effect was noted but deserves to be confirmed over longer follow ups.

Molecular and Metabolic Imaging in Multiple Sclerosis

Multiple sclerosis is a multifactorial disease with heterogeneous pathogenetic mechanisms, which deserve to be studied to evaluate new possible targets for treatments and improve patient management. MR spectroscopy and PET allow assessing in vivo the molecular and metabolic mechanisms underlying the pathogenesis of multiple sclerosis. This article focuses on the relationship between these imaging techniques and the biologic and chemical pathways leading to multiple sclerosis pathology and its clinical features. Future directions of research are also presented.

Microglial Phenotypes and Functions in Multiple Sclerosis

Microglia are the resident immune cells that constantly survey the central nervous system. They can adapt to their environment and respond to injury or insult by altering their morphology, phenotype, and functions. It has long been debated whether microglial activation is detrimental or beneficial in multiple sclerosis (MS). Recently, the two opposing yet connected roles of microglial activation have been described with the aid of novel microglial markers, RNA profiling, and in vivo models. In this review, microglial phenotypes and functions in the context of MS will be discussed with evidence from both human pathological studies, in vitro and in vivo models. Microglial functional diversity-phagocytosis, antigen presentation, immunomodulation, support, and repair-will also be examined in detail. In addition, this review discusses the emerging evidence for microglia-related targets as biomarkers and therapeutic targets for MS.

Microglial activation and the nitric oxide/cGMP/PKG pathway underlie enhanced neuronal vulnerability to mitochondrial dysfunction in experimental multiple sclerosis

During multiple sclerosis (MS), a close link has been demonstrated to occur between inflammation and neuro-axonal degeneration, leading to the hypothesis that immune mechanisms may promote neurodegeneration, leading to irreversible disease progression. Energy deficits and inflammation-driven mitochondrial dysfunction seem to be involved in this process. In this work we investigated, by the use of striatal electrophysiological field-potential recordings, if the inflammatory process associated with experimental autoimmune encephalomyelitis (EAE) is able to influence neuronal vulnerability to the blockade of mitochondrial complex IV, a crucial component for mitochondrial activity responsible of about 90% of total cellular oxygen consumption. We showed that during the acute relapsing phase of EAE, neuronal susceptibility to mitochondrial complex IV inhibition is markedly enhanced. This detrimental effect was counteracted by the pharmacological inhibition of microglia, of nitric oxide (NO) synthesis and its intracellular pathway (involving soluble guanylyl cyclase, sGC, and protein kinase G, PKG). The obtained results suggest that mitochondrial complex IV exerts an important role in maintaining neuronal energetic homeostasis during EAE. The pathological processes associated with experimental MS, and in particular the activation of microglia and of the NO pathway, lead to an increased neuronal vulnerability to mitochondrial complex IV inhibition, representing promising pharmacological targets.

No evidence of disease activity is associated with reduced rate of axonal retinal atrophy in MS

Objective:

To explore, in a longitudinal study, the usefulness of optical coherence tomography (OCT) in monitoring people with multiple sclerosis (MS) by testing the association between retinal nerve fiber layer (RNFL) thinning and clinical and brain MRI criteria of no evidence of disease activity (NEDA).

Methods:

OCT, visual evoked potentials (VEPs), and disability, using the Expanded Disability Status Scale (EDSS), were tested at baseline and after 2 years in 72 patients, 63 with routine yearly brain MRI.

Results:

Longitudinal mean binocular RNFL thinning, in absence of optic neuritis during follow-up, was correlated with EDSS worsening, also controlling for baseline EDSS, RNFL, disease duration, and MS subtype (Spearman ρ −0.462, p < 0.001; partial correlation coefficient −0.437, p < 0.001). At follow-up, patients classified as NEDA (20; 31.7%) had RNFL loss of −0.93 μm ± 1.35 SD, while patients with active disease had −2.83 μm ± 2 SD thinning (t test; p < 0.001). At logistic regression, mean RNFL reduction correctly classified 76.2% of patients as NEDA at 2 years (R2 0.355; p = 0.003). A cutoff of −1.25 μm RNFL loss classified NEDA status with specificity 81.4% and sensitivity 80% (receiver operating characteristic curve: area under the curve 0.8; p < 0.001). No significant longitudinal correlations were found between changes in RNFL and in VEP latencies or scores.

Conclusions:

NEDA is associated with a relatively preserved RNFL over 2 years. A greater neuroretinal loss was detected even in patients with clinical evidence of disease activity independently from changes in brain MRI lesions, prompting further validation of OCT as an additional tool in MS monitoring.

Cerebrospinal fluid mtDNA concentration is elevated in multiple sclerosis disease and responds to treatment

BACKGROUND

Mitochondrial dysfunction is increasingly recognized as an important feature of multiple sclerosis (MS) pathology and may be relevant for clinical disease progression. However, it is unknown whether mitochondrial DNA (mtDNA) levels in the cerebrospinal fluid (CSF) associate with disease progression and therapeutic response.

OBJECTIVES

To evaluate whether CSF concentrations of mtDNA in MS patients can serve as a marker of ongoing neuropathology and may be helpful to differentiate between MS disease subtypes. To explore the effect of disease-modifying therapies on mtDNA levels in the CSF.

METHODS

CSF mtDNA was measured using a digital polymerase chain reaction (PCR) CSF mtDNA in two independent MS cohorts. The cohorts included 92 relapsing-remitting multiple sclerosis (RRMS) patients, 40 progressive multiple sclerosis (PMS) patients (27 secondary progressive and 13 primary progressive), 50 various neurologic disease controls, and 5 healthy controls.

RESULTS

Patients with PMS showed a significant increase in CSF mtDNA compared to non-inflammatory neurologic disease controls. Patients with higher T2 lesion volumes and lower normalized brain volumes showed increased concentration of mtDNA. Patients treated with fingolimod had significantly lower mtDNA copy levels at follow-up compared to baseline.

CONCLUSION

Our results showed a non-specific elevation of concentration of mtDNA in PMS patients. mtDNA concentrations respond to fingolimod and may be used to monitor biological effect of this treatment.

[Multiple sclerosis - a mitochondria-mediated disease?]

BACKGROUND Mitochondria play an important role in the pathogenesis of various neurodegenerative disorders, including Parkinson's disease. Neurodegenerative changes occur early in the course of multiple sclerosis (MS). This article aims to present information on a possible association between mitochondrial dysfunction and multiple sclerosis.MATERIAL AND METHOD The article is based on original and review articles selected following a literature search in PubMed, restricted to articles written in English, and concluded in May 2016. The literature search resulted in a total of 2276 articles. After a discretionary evaluation by the authors, 71 articles were read in full. Of these, 19 were used as references. In addition, we included 15 articles from reference lists and seven from the authors' own literature archive.RESULTS Mitochondrial changes have been demonstrated in affected areas of the brains of patients with MS. Although some of the changes may be attributed to mitochondrial damage that is secondary to inflammation, others may be compensatory due to the increased energy demands of demyelinated axons. The type of mitochondrial damage varies and is dependent on the pathology that triggers it.INTERPRETATION Mitochondrial damage secondary to inflammation, combined with increased energy demands secondary to demyelination, may result in a chronic energy deficiency in the central nervous system. This in turn may lead to neurodegeneration. Improved knowledge of the role of mitochondria in MS, both secondary to inflammation and possibly as a direct contributor to neurodegeneration, may provide a better understanding of the pathogenesis of the disease and perhaps contribute to new treatment options.

Myelin-oligodendrocyte-glycoprotein (MOG) autoantibodies as potential markers of severe optic neuritis and subclinical retinal axonal degeneration

Antibodies against conformation-dependent epitopes of myelin-oligodendrocyte-glycoprotein (MOG-abs) are present in subgroups of neuromyelitis optica spectrum disorder (NMOSD), recurrent optic neuritis (rON), multiple sclerosis (MS), and anti-NMDAR encephalitis. Using optical coherence tomography (OCT) we assessed whether MOG-abs might serve as potential marker of retinal axonal degeneration. We investigated a clinically heterogeneous cohort of 13 MOG-abs-positive patients (4 MOG-abs-positive rON, 4 MOG-abs-positive adult MS, 3 MOG-abs-positive relapsing encephalomyelitis, 2 MOG-abs-positive aquaporin-4-abs-negative NMOSD). As controls, we studied 13 age, sex and ON episode(s)-matched MOG-abs and aquaporin-4-abs-negative (AQP4-abs-negative) MS patients and 13 healthy controls (HC). In addition, we investigated 19 unmatched AQP4-abs-positive MOG-abs-negative NMOSD subjects. Considering all eyes, global pRNFL [in µm, mean (SD)] was significantly reduced in MOG-abs-positive patients [72.56 (22.71)] compared to MOG-abs-negative MS [80.81 (13.55), p = 0.0128], HCs [103.54 (8.529), p = 0.0014] and NMOSD [88.32 (18.43), p = 0.0353]. Non ON eyes from MOG-abs-positive subjects showed significant subclinical atrophy of temporal pRNFL quadrants. Microcystic macular edema (MME) was observed only in eyes of MOG-abs-positive (24%) and AQP4-abs-positive NMOSD (5.6%), but not in MOG-abs-negative MS or HC (p < 0.01). MOG-abs may serve as potential marker of retinal degeneration. Specifically, MOG-abs-related OCT features predominate in temporal pRNFL quadrants (resembling the MS retinal pattern), might be more severe than AQP4-abs-positive NMOSD, indicate subclinical pathology, and may be associated with MME.

Cervical Spondylotic Myelopathy: Metabolite Changes in the Primary Motor Cortex after Surgery

Purpose To characterize longitudinal metabolite alterations in the motor cortex of patients with cervical spondylotic myelopathy (CSM) by using proton magnetic resonance (MR) spectroscopy and to evaluate white matter integrity with diffusion-tensor imaging in patients who are recovering neurologic function after decompression surgery. Materials and Methods Informed written consent was obtained for all procedures and the study was approved by Western University's Health Sciences Research Ethics Board. Twenty-eight patients with CSM and 10 healthy control subjects were prospectively recruited and underwent two separate 3-T MR imaging examinations 6 months apart. Patients with CSM underwent surgery after the first examination. N-acetylaspartate (NAA), an indicator of neuronal mitochondrial function, normalized to creatine (Cr) levels were measured from the motor cortex contralateral to the greater functional deficit side in the patient group and on both sides in the control group. Fractional anisotropy and mean diffusivity were measured by means of diffusion-tensor imaging in the white matter adjacent to the motor and sensory cortices of the hand and the entire cerebral white matter. Clinical data were analyzed by using Student t tests. Results In patients with CSM, NAA normalized to Cr (NAA/Cr) levels were significantly lower 6 months after surgery (1.48 ± 0.08; P < .03) compared with preoperative levels (1.73 ± 0.09), despite significant improvement in clinical questionnaire scores. Fractional anisotropy and mean diffusivity were the same (P > .05) between the patient and control groups in all measured regions at all time points. Conclusion NAA/Cr levels decreased in the motor cortex in patients with CSM 6 months after successful surgery. Intact white matter integrity with decreased NAA/Cr levels suggests that mitochondrial metabolic dysfunction persists after surgery. ^© RSNA, 2016 Online supplemental material is available for this article.

Mitochondrial STAT3 is negatively regulated by SOCS3 and upregulated after spinal cord injury

Suppressor of cytokine signaling-3 (SOCS3) expression is induced by the Janus kinase (JAK)-signal transducer and activator of transcription 3 (STAT3) signaling pathway. SOCS3 then acts as a feedback inhibitor of JAK-STAT signaling. Previous studies have shown that knocking down SOCS3 in spinal cord neurons with Lentiviral delivery of SOCS3-targeting shRNA (shSOCS3) increased spinal cord injury (SCI)-induced tyrosine phosphorylation of STAT3 (P-STAT3 Tyr), which in part contributed to decreased neuronal death and demyelination as well as enhanced dendritic regeneration and protection of neuronal morphology after SCI. However, the role of serine phosphorylation of STAT3 (P-STAT3 Ser) is in large part undetermined. Our purposes of this study were to evaluate the expression patterns of P-STAT3 Ser and to explore the possible role of SOCS3 in the regulation of P-STAT3 Ser expression. Immunoblot analyses demonstrated that Oncostatin M (OSM), a member of the interleukin-6 (IL-6) cytokine family, induced both P-STAT3 Tyr and P-STAT3 Ser in SH-SY5Y cells. Subcellular fractionation further revealed that P-STAT3 Ser was localized in mitochondria. Overexpression of SOCS3 with a Lentivirus-mediated approach in SH-SY5Y cells inhibited OSM-induced P-STAT3 Ser in both cytosol and mitochondria fractions. In contrast, OSM-induced P-STAT3 Ser was further upregulated in both cytosol and mitochondria when SOCS3 was knocked down by Lentivirus-delivered shSOCS3. Using a rat T8 spinal cord complete transection model, we found that SCI induced upregulation of P-STAT3 Ser in the mitochondria of macrophages/microglia and neurons both rostral and caudal to the injury site of spinal cord. Collectively, these results suggest that SOCS3 regulation of STAT3 signaling plays critical roles in stress conditions.

SIRT1 and NAD+ precursors: Therapeutic targets in multiple sclerosis a review

Neurodegeneration is an important determinant of disability in multiple sclerosis (MS) but while currently approved treatments reduce inflammation, they have not been shown to reduce neurodegeneration. SIRT1, a NAD dependent protein deacetylase, has been implicated in the pathogenesis of neurodegeneration in neurological diseases including MS. We have studied the role of SIRT1 in experimental autoimmune encephalomyelitis (EAE) and found evidence for a neuroprotective role. In this review we summarize the most recent findings from the use of SIRT1 activators and SIRT1 overexpression in transgenic mice. These data support provide a rational for the use of SIRT1 activators in MS.

Meta-Analysis of Multiple Sclerosis Microarray Data Reveals Dysregulation in RNA Splicing Regulatory Genes

Abnormalities in RNA metabolism and alternative splicing (AS) are emerging as important players in complex disease phenotypes. In particular, accumulating evidence suggests the existence of pathogenic links between multiple sclerosis (MS) and altered AS, including functional studies showing that an imbalance in alternatively-spliced isoforms may contribute to disease etiology. Here, we tested whether the altered expression of AS-related genes represents a MS-specific signature. A comprehensive comparative analysis of gene expression profiles of publicly-available microarray datasets (190 MS cases, 182 controls), followed by gene-ontology enrichment analysis, highlighted a significant enrichment for differentially-expressed genes involved in RNA metabolism/AS. In detail, a total of 17 genes were found to be differentially expressed in MS in multiple datasets, with CELF1 being dysregulated in five out of seven studies. We confirmed CELF1 downregulation in MS (p = 0.0015) by real-time RT-PCRs on RNA extracted from blood cells of 30 cases and 30 controls. As a proof of concept, we experimentally verified the unbalance in alternatively-spliced isoforms in MS of the NFAT5 gene, a putative CELF1 target. In conclusion, for the first time we provide evidence of a consistent dysregulation of splicing-related genes in MS and we discuss its possible implications in modulating specific AS events in MS susceptibility genes.

Metabolic dysfunctions in multiple sclerosis: implications as to causation, early detection, and treatment, a case control study

Background

Biochemical changes associated with multiple sclerosis (MS), and its various clinical forms have not been characterized well. Therefore, we investigated the biochemistry of MS in relation to its natural history using targeted lipidomics platforms.

Methods

Cross-sectional serum samples from 24 secondary progressive (SPMS), 100 relapsing remitting (RRMS), 19 primary progressive MS (PPMS), and 55 age-matched control subjects were analyzed by flow injection tandem mass spectrometry for very long chain fatty acid (VLCFA) containing phosphatidyl ethanolamines (PtdEtn), plasmalogen ethanolamines (PlsEtn) and for novel anti-inflammatory gastrointestinal tract acids (GTAs). Changes in analyte levels relative to healthy controls were correlated with the disease stage and disease duration.

Results

RRMS subjects having <13 years disease duration had elevated levels (p < 0.05) of anti-inflammatory metabolites (GTAs) and normal levels (p > 0.05) of mitochondrial stress biomarkers (VLCFA-PtdEtn), compared to controls. SPMS subjects had statistically similar levels of anti-inflammatory metabolites (GTAs), elevated mitochondrial stress metabolites (VLCFA-PtdEtn) and elevated peroxisomal metabolites (PlsEtn) compared to controls (p < 0.05). RRMS subjects with > = 13 years disease duration exhibited metabolic profiles intermediate between short-duration RRMS and SPMS, based on statistical significance. Therefore, RRMS cohort appear to comprise of two metabolically distinct subpopulations. The key clinical discriminator of these two groups was disease duration. PPMS patients exhibited metabolic profiles distinct from RRMS and SPMS.

Conclusions

These data indicate that inflammation and mitochondrial stress are intricately involved in the etiology of MS and that progression in MS can potentially be monitored using serum metabolic biomarkers.

Exploring the origins of grey matter damage in multiple sclerosis

Multiple sclerosis is characterized at the gross pathological level by the presence of widespread focal demyelinating lesions of the myelin-rich white matter. However, it is becoming clear that grey matter is not spared, even during the earliest phases of the disease. Furthermore, grey matter damage may have an important role both in physical and cognitive disability. Grey matter pathology involves both inflammatory and neurodegenerative mechanisms, but the relationship between the two is unclear. Histological, immunological and neuroimaging studies have provided new insight in this rapidly expanding field, and form the basis of the most recent hypotheses on the pathogenesis of grey matter damage.

Demyelination as a rational therapeutic target for ischemic or traumatic brain injury

Previous research on stroke and traumatic brain injury (TBI) heavily emphasized pathological alterations in neuronal cells within gray matter. However, recent studies have highlighted the equal importance of white matter integrity in long-term recovery from these conditions. Demyelination is a major component of white matter injury and is characterized by loss of the myelin sheath and oligodendrocyte cell death. Demyelination contributes significantly to long-term sensorimotor and cognitive deficits because the adult brain only has limited capacity for oligodendrocyte regeneration and axonal remyelination. In the current review, we will provide an overview of the major causes of demyelination and oligodendrocyte cell death following acute brain injuries, and discuss the crosstalk between myelin, axons, microglia, and astrocytes during the process of demyelination. Recent discoveries of molecules that regulate the processes of remyelination may provide novel therapeutic targets to restore white matter integrity and improve long-term neurological recovery in stroke or TBI patients.

Complex I subunit gene therapy with NDUFA6 ameliorates neurodegeneration in EAE

PURPOSE

To address the permanent disability induced by mitochondrial dysfunction in experimental autoimmune encephalomyelitis (EAE).

METHODS

Mice sensitized for EAE were rescued by intravitreal injection of adeno-associated viral vector serotype 2 with the complex I subunit gene scAAV-NDUFA6Flag. Controls were injected with a mitochondrially targeted red fluorescent protein (scAAV-COX8-cherry). Another group received scAAV-COX8-cherry, but was not sensitized for EAE. Serial pattern electroretinograms (PERGs) and optical coherent tomography (OCT) evaluated visual function and structure of the retina at 1, 3, and 6 months post injection (MPI). Treated mice were killed 6 MPI for histopathology. Immunodetection of cleaved caspase 3 gauged apoptosis. Complex I activity was assessed spectrophotometrically. Expression of NDUFA6Flag in the retina and optic nerve were evaluated between 1 week to 1 month post injection by RT-PCR, immunofluorescence and immunoblotting.

RESULTS

Reverse transcription-PCR and immunoblotting confirmed NDUFA6Flag overexpression with immunoprecipitation and blue native PAGE showing integration into murine complex I. Overexpression of NDUFA6Flag in the visual system of EAE mice rescued retinal complex I activity completely, axonal loss by 73%, and retinal ganglion cell (RGC) loss by 88%, RGC apoptosis by 66%, and restored the 33% loss of complex I activity in EAE to normal levels; thereby, preventing loss of vision indicated by the 43% reduction in the PERG amplitudes of EAE mice.

CONCLUSIONS

NDUFA6 gene therapy provided long-term suppression of neurodegeneration in the EAE animal model suggesting that it may also ameliorate the mitochondrial dysfunction associated with permanent disability in optic neuritis and MS patients.

Axonal degeneration in multiple sclerosis: can we predict and prevent permanent disability?

Axonal degeneration is a major determinant of permanent neurological impairment during multiple sclerosis (MS). Due to the variable course of clinical disease and the heterogeneity of MS lesions, the mechanisms governing axonal degeneration may differ between disease stages. While the etiology of MS remains elusive, there now exist potential prognostic biomarkers that can predict the conversion to clinically definite MS. Specialized imaging techniques identifying axonal injury and drop-out are becoming established in clinical practice as a predictive measure of MS progression, such as optical coherence tomography (OCT) or diffusion tensor imaging (DTI). However, these imaging techniques are still being debated as predictive biomarkers since controversy surrounds their lesion-specific association with expanded disability status scale (EDSS). A more promising diagnostic measure of axonal degeneration has been argued for the detection of reduced N-acetyl aspartate (NAA) and Creatine ratios via magnetic resonance spectroscopic (MRS) imaging, but again fail with its specificity for predicting actual axonal degeneration. Greater accuracy of predictive biomarkers is therefore warranted and may include CSF neurofilament light chain (NF-L) and neurofilament heavy chain (NF-H) levels, for progressive MS. Furthermore, defining the molecular mechanisms that occur during the neurodegenerative changes in the various subgroups of MS may in fact prove vital for the future development of efficacious neuroprotective therapies. The clinical translation of a combined Na⁺ and Ca²⁺ channel blocker may lead to the establishment of a bona fide neuroprotective agent for the treatment of progressive MS. However, more specific therapeutic targets to limit axonal damage in MS need investigation and may include such integral axonal proteins such as the collapsin response mediator protein-2 (CRMP-2), a molecule which upon post-translational modification may propagate axonal degeneration in MS. In this review, we discuss the current clinical determinants of axonal damage in MS and consider the cellular and molecular mechanisms that may initiate these neurodegenerative changes. In particular we highlight the therapeutic candidates that may formulate novel therapeutic strategies to limit axonal degeneration and EDSS during progressive MS.

Curcumin inhibits mitochondrial injury and apoptosis from the early stage in EAE mice

The exact pathophysiological change concerning mitochondrial injury and oligodendrocyte apoptosis in MS and EAE model is still unknown. Whether curcumin is able to inhibit mitochondrial injury and suppress the apoptosis in the early stages of MS/EAE is still unclear. We first explored mitochondrial injury and apoptosis at different time points p.i. in C57 BL/6 EAE mice. We then explored the effects of curcumin on mitochondria and apoptosis. Results showed that mitochondrial injury can be observed 3 days p.i. Apoptosis in the spinal cord occurred 3 days p.i. and the apoptotic cells were shown to be oligodendrocytes and neuronal cells. Curcumin significantly reduced the number of apoptotic cells and inhibited the upregulation of cyt-c, caspase-9, and caspase-3 at 7 days p.i. in the EAE mice. These observations demonstrate that mitochondrial injury and oligodendrocyte/neuronal apoptosis occur in the early stages of EAE. Curcumin can inhibit apoptosis in EAE mice which maybe act through protection of mitochondrial injury and inhibition of the intrinsic apoptotic pathway.

Evidence linking oxidative stress, mitochondrial dysfunction, and inflammation in the brain of individuals with autism

Autism spectrum disorders (ASDs) are a heterogeneous group of neurodevelopmental disorders that are defined solely on the basis of behavioral observations. Therefore, ASD has traditionally been framed as a behavioral disorder. However, evidence is accumulating that ASD is characterized by certain physiological abnormalities, including oxidative stress, mitochondrial dysfunction and immune dysregulation/inflammation. While these abnormalities have been reported in studies that have examined peripheral biomarkers such as blood and urine, more recent studies have also reported these abnormalities in brain tissue derived from individuals diagnosed with ASD as compared to brain tissue derived from control individuals. A majority of these brain tissue studies have been published since 2010. The brain regions found to contain these physiological abnormalities in individuals with ASD are involved in speech and auditory processing, social behavior, memory, and sensory and motor coordination. This manuscript examines the evidence linking oxidative stress, mitochondrial dysfunction and immune dysregulation/inflammation in the brain of ASD individuals, suggesting that ASD has a clear biological basis with features of known medical disorders. This understanding may lead to new testing and treatment strategies in individuals with ASD.

The role of glutamate and its receptors in multiple sclerosis

Glutamate is an excitatory neurotransmitter of the central nervous system, which has a central role in a complex communication network established between neurons, astrocytes, oligodendrocytes, and microglia. Multiple abnormal triggers such as energy deficiency, oxidative stress, mitochondrial dysfunction, and calcium overload can lead to abnormalities in glutamate signaling. Thus, the disturbance of glutamate homeostasis could affect practically all physiological functions and interactions of brain cells, leading to excitotoxicity. Excitotoxicity is the pathological process by which nerve cells are damaged or killed by excessive stimulation by glutamate. Although neuron degeneration and death are the ultimate consequences of multiple sclerosis (MS), it is now widely accepted that alterations in the function of surrounding glial cells are key features in the progression of the disease. The present knowledge raise the possibility that the modulation of glutamate release and transport, as well as receptors blockade or glutamate metabolism modulation, might be relevant targets for the development of future therapeutic interventions in MS.

Metabolomic profiling in multiple sclerosis: insights into biomarkers and pathogenesis

Metabolomics enables the provision of sensitive bio-markers of disease. We performed 800 MHz 1H-nuclear magnetic resonance (NMR) spectroscopic analyses of cerebrospinal fluid (CSF) specimens to identify biomarkers of multiple sclerosis (MS), yielding reproducible detection of 15 metabolites from MS ( n=15) and non-MS ( n=17) patients. Mean levels of choline, myo-inositol and threonate were increased, whereas 3-hydroxybutyrate, citrate, phenylalanine, 2-hydroxyisovalerate and mannose were decreased in MS-derived CSF ( p<0.05), suggesting alterations to energy and phospholipid metabolism. Multivariate hierarchal cluster analysis indicated a high correlation within the metabolite profiles, significantly clustering samples into the two clinical groups, which was corroborated using principal components analysis. CSF metabolomics have the capacity to yield quantitative biomarkers and insights into the pathogenesis of MS.

Stressed cybrids model demyelinated axons in multiple sclerosis

Multiple sclerosis is likely caused by a complex interaction of multiple genes and environmental factors. The contribution of mitochondrial DNA genetic backgrounds has been frequently reported. To evaluate the effect of mitochondrial DNA haplogroups in the same genetic and environmental circumstances, we have built human transmitochondrial cell lines and simulated the effect of axon demyelination, one of the hallmarks of multiple sclerosis pathology, by altering the ionic gradients through the plasmalemma and increasing ATP consumption. In this model, mitochondrial biogenesis is observed. This process is larger in Uk cybrids, which mirrors their lower oxidative phosphorylation capacity in basal conditions. This model replicates a process occurring in both patients suffering from multiple sclerosis and several animal models of axon demyelination. Therefore, it can be used to analyze the contribution of various mitochondrial DNA genotypes to multiple sclerosis. In this sense, a longer or stronger energy stress, such as that associated with demyelinated axons in multiple sclerosis, could make Uk individuals more susceptible to this pathology. Finally, pharmacologic compounds targeted to mitochondrial biogenesis could be a potential therapy for multiple sclerosis.

Interferon-β1a protects neurons against mitochondrial toxicity via modulation of STAT1 signaling: electrophysiological evidence

Multiple sclerosis, one of the main causes of non-traumatic neurological disability in young adults, is an inflammatory and neurodegenerative disorder of the central nervous system. Although the pathogenesis of neuroaxonal damage occurring during the course of the disease is still largely unknown, there is accumulating evidence highlighting the potential role of mitochondria in multiple sclerosis-associated neuronal degeneration. The aim of the present study was to investigate, by utilizing electrophysiological techniques in brain striatal slices, the potential protective effects of interferon-β1a, one of the most widely used medication for multiple sclerosis, against acute neuronal dysfunction induced by mitochondrial toxins. Interferon-β1a was found to exert a dose-dependent protective effect against the progressive loss of striatal field potential amplitude induced by the mitochondrial complex I inhibitor rotenone. Interferon-β1a also reduced the generation of the rotenone-induced inward current in striatal spiny neurons. Conversely, interferon-β1a did not influence the electrophysiological effects of the mitochondrial complex II inhibitor 3-nitropropionic acid. The protective effect of interferon-β1a against mitochondrial complex I inhibition was found to be dependent on the activation of STAT1 signaling. Conversely, endogenous dopamine depletion and the modulation of the p38 MAPK and mTOR pathways did not influence the effects of interferon-β1a. During experimental autoimmune encephalomyelitis (EAE) striatal rotenone toxicity was enhanced but the protective effect of interferon-β1a was still evident. These results support future studies investigating the role played by specific intracellular signaling pathways in mediating the potential link among inflammation, mitochondrial impairment and neuroaxonal degeneration in multiple sclerosis.

Mitochondrial dysfunction in demyelinating diseases

Dysfunction of the mitochondrial (mt) system is thought to play an important role in the mechanism of progression of various neurodegenerative disorders, including demyelinating disorders. They are characterized by neuroinflammation, ultimately leading to neurodegeneration. Mitochondria (mt) dysfunction is closely related to the mechanism of neuroinflammation, causing increased production of reactive oxygen species, which is detrimental to neurons and glia. Vice versa, neuroinflammation is increasingly recognized to produce mt failure, which then contributes to further neuronal injury and degeneration. Multiple sclerosis and X-linked adrenoleukodystrophy are examples of neurodemyelinating diseases that despite having a diverse etiology have in common a progressive course and significant neuroinflammation and neurodegeneration, leading to severe neurologic disability. The scientific community has become increasingly interested in how mt dysfunction relates to neuroinflammation and demyelination and what role it may play in the natural history of progressive demyelinating diseases. Research studies investigating how mt failure contributes to the progression of these conditions are emerging. A better understanding of the role of oxidative stress in progressive inflammatory demyelinating diseases might generate new potential neuroprotective therapeutic approaches for these devastating neurologic conditions.

Optical Coherence Tomography Reveals Distinct Patterns of Retinal Damage in Neuromyelitis Optica and Multiple Sclerosis

Background

Neuromyelitis optica (NMO) and relapsing-remitting multiple sclerosis (RRMS) are difficult to differentiate solely on clinical grounds. Optical coherence tomography (OCT) studies investigating retinal changes in both diseases focused primarily on the retinal nerve fiber layer (RNFL) while rare data are available on deeper intra-retinal layers.

Objective

To detect different patterns of intra-retinal layer alterations in patients with NMO spectrum disorders (NMOSD) and RRMS with focus on the influence of a previous optic neuritis (ON).

Methods

We applied spectral-domain OCT in eyes of NMOSD patients and compared them to matched RRMS patients and healthy controls (HC). Semi-automatic intra-retinal layer segmentation was used to quantify intra-retinal layer thicknesses. In a subgroup low contrast visual acuity (LCVA) was assessed.

Results

NMOSD-, MS- and HC-groups, each comprising 17 subjects, were included in analysis. RNFL thickness was more severely reduced in NMOSD compared to MS following ON. In MS-ON eyes, RNFL thinning showed a clear temporal preponderance, whereas in NMOSD-ON eyes RNFL was more evenly reduced, resulting in a significantly lower ratio of the nasal versus temporal RNFL thickness. In comparison to HC, ganglion cell layer thickness was stronger reduced in NMOSD-ON than in MS-ON, accompanied by a more severe impairment of LCVA. The inner nuclear layer and the outer retinal layers were thicker in NMOSD-ON patients compared to NMOSD without ON and HC eyes while these differences were primarily driven by microcystic macular edema.

Conclusion

Our study supports previous findings that ON in NMOSD leads to more pronounced retinal thinning and visual function impairment than in RRMS. The different retinal damage patterns in NMOSD versus RRMS support the current notion of distinct pathomechanisms of both conditions. However, OCT is still insufficient to help with the clinically relevant differentiation of both conditions in an individual patient.

NADH-dehydrogenase type-2 suppresses irreversible visual loss and neurodegeneration in the EAE animal model of MS

To address mitochondrial dysfunction that mediates irreversible visual loss and neurodegeneration of the optic nerve in the experimental autoimmune encephalomyelitis (EAE) animal model of multiple sclerosis (MS), mice sensitized for EAE were vitreally injected with self-complementary adenoassociated virus (scAAV) containing the NADH-dehydrogenase type-2 (NDI1) complex I gene that quickly expressed in mitochondria of almost all retinal ganglion cells (RGCs). Visual function assessed by pattern electroretinograms (PERGs) reduced by half in EAE showed no significant reductions with NDI1. Serial optical coherence tomography (OCT) revealed significant inner retinal thinning with EAE that was suppressed by NDI1. Although complex I activity reduced 80% in EAE was not improved by NDI1, in vivo fluorescent probes indicated mitochondrial oxidative stress and apoptosis of the EAE retina were reduced by NDI1. Finally, the 42% loss of axons in the EAE optic nerve was ameliorated by NDI1. Targeting the dysfunctional complex I of EAE responsible for loss of respiration, mitochondrial oxidative stress and apoptosis may be a novel approach to address neuronal and axonal loss responsible for permanent disability that is unaltered by current disease modifying drugs for MS that target inflammation.

Polyphenols: multipotent therapeutic agents in neurodegenerative diseases

Aging leads to numerous transitions in brain physiology including synaptic dysfunction and disturbances in cognition and memory. With a few clinically relevant drugs, a substantial portion of aging population at risk for age-related neurodegenerative disorders require nutritional intervention. Dietary intake of polyphenols is known to attenuate oxidative stress and reduce the risk for related neurodegenerative diseases such as Alzheimer's disease (AD), stroke, multiple sclerosis (MS), Parkinson's disease (PD), and Huntington's disease (HD). Polyphenols exhibit strong potential to address the etiology of neurological disorders as they attenuate their complex physiology by modulating several therapeutic targets at once. Firstly, we review the advances in the therapeutic role of polyphenols in cell and animal models of AD, PD, MS, and HD and activation of drug targets for controlling pathological manifestations. Secondly, we present principle pathways in which polyphenol intake translates into therapeutic outcomes. In particular, signaling pathways like PPAR, Nrf2, STAT, HIF, and MAPK along with modulation of immune response by polyphenols are discussed. Although current polyphenol researches have limited impact on clinical practice, they have strong evidence and testable hypothesis to contribute clinical advances and drug discovery towards age-related neurological disorders.

Isoprostanes in clinically isolated syndrome and early multiple sclerosis as biomarkers of tissue damage and predictors of clinical course

BACKGROUND

Isoprostanes (IsoP) are sensitive biomarkers of oxidative stress. Their cerebrospinal-fluid (CSF) level is increased in several neurological conditions, including multiple sclerosis (MS). In particular, in relapsing-remitting MS, IsoP have been proposed as an index of neurodegenerative processes. The mechanisms leading to neuroaxonal damage in MS are not fully understood but oxidative mechanisms play a substantial role. Although axonal loss is present in MS patients since their first clinical symptoms, IsoP levels at this early stage have not been evaluated yet.

OBJECTIVES

The objectives of this study were (a) to assess IsoP levels in CSF of patients with a first clinical attack suggestive of MS; (b) to correlate IsoP levels with magnetic resonance imaging (MRI) measures of brain damage and (c) to assess IsoP value in predicting disease clinical evolution.

METHODS

Thirty-nine patients with a first clinical attack suggestive of MS underwent neurological examination, lumbar puncture with IsoP levels quantification and conventional/spectroscopic-MRI. Patients were followed up for 24 months.

RESULTS

CSF IsoP levels were higher in patients than controls (mean ± standard deviation (SD) 123.4 ± 185.8 vs 4.5 ± 2.9 pg/ml; p<0.0001) and inversely correlated to normalized brain volume (p=0.04) and N-acetylaspartate/choline (NAA/Cho) (p=0.01). The risk of experiencing clinical relapses differed according to IsoP level: subjects with levels higher than 95 pg/ml (a cut-off value resulting from ROC analysis) were more likely to relapse than patients with levels equal or lower than 95 pg/ml (59% vs 27% respectively; p=0.03).

CONCLUSIONS

CSF IsoP might be useful biomarkers of tissue damage in MS with a predictive value of disease course.