Mitochondrial Degeneration in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder that causes motor neuron degeneration, progressive skeletal muscle atrophy, paralysis, and death. To understand the mechanism of motor neuron degeneration, we have analyzed the clinical disease progression and the pathological changes in a transgenic mouse model for ALS. We found massive mitochondrial vacuolation at the onset of disease. By detailed morphological observations, we have determined that this mitochondrial vacuolation is developed from expansion of mitochondrial intermembrane space and extension of the outer membrane and involves peroxisomes. Lysosomes do not actively participate at all stages of this vacuolation. We conclude that this mitochondrial vacuolation is neither classical mitochondrial permeability transition nor autophagic vacuolation. Thus, this appears to be a new form of mitochondrial vacuolation and we term this as mitochondrial vacuolation by intermembrane space expansion or MVISE.     

Patterns of Spontaneous Brain Activity in Amyotrophic Lateral Sclerosis: A Resting-State fMRI Study

By detecting spontaneous low-frequency fluctuations (LFF) of blood oxygen level–dependent (BOLD) signals, resting-state functional magnetic resonance imaging (rfMRI) measurements are believed to reflect spontaneous cerebral neural activity. Previous fMRI studies were focused on the examination of motor-related areas and little is known about the functional changes in the extra-motor areas in amyotrophic lateral sclerosis (ALS) patients. The aim of this study is to investigate functional cerebral abnormalities in ALS patients on a whole brain scale. Twenty ALS patients and twenty age- and sex-matched healthy volunteers were enrolled. Voxel-based analysis was used to characterize the alteration of amplitude of low frequency fluctuation (ALFF). Compared with the controls, the ALS patients showed significantly decreased ALFF in the visual cortex, fusiform gyri and right postcentral gyrus; and significantly increased ALFF in the left medial frontal gyrus, and in right inferior frontal areas after grey matter (GM) correction. Taking GM volume as covariates, the ALFF results were approximately consistent with those without GM correction. In addition, ALFF value in left medial frontal gyrus was negatively correlated with the rate of disease progression and duration. Decreased functional activity observed in the present study indicates the underlying deficits of the sensory processing system in ALS. Increased functional activity points to a compensatory mechanism. Our findings suggest that ALS is a multisystem disease other than merely motor dysfunction and provide evidence that alterations of ALFF in the frontal areas may be a special marker of ALS.     

Anti-Ganglioside Antibodies in Amyotrophic Lateral Sclerosis Revisited

Background

Amyotrophic Lateral Sclerosis (ALS) is a devastating neurodegenerative disorder with typical onset in the 5^th- 6^th decade of life. The hypothesis of an autoimmune origin of ALS receives less attention today, but immunological phenomena still seem to be involved and mechanisms such as protective autoimmunity may be important. Detection of antibodies against a variety of gangliosides has been repeatedly described in ALS-patients by several authors, but widely differing frequencies and titres have been reported. Therefore, we investigated the presence of six common antibodies with a commercially available test panel for GA1, GM1, GM2, GD1a, GD1b and GQ1b in a large group of clinically well-characterized ALS patients and compared them to a collective of 200 healthy blood donors.

Methods

IgG and IgM antibodies to the six gangliosides asialoGM1 (GA1), GM1, GM2, GD1a, GD1b, GQ1b were determined by GanglioCombi ELISA in sera of 84 ALS patients. Results were expressed as a %-ratio of a highly positive control and categorized as negative (<30%), borderline (30–50%), moderately (50–100%) and strongly positive (>100%). The values obtained from 200 Swiss blood donors served as a reference group.

Results

In twenty-two (26.2%) ALS-patients elevated anti-ganglioside antibodies could be detected: Taking all subspecific antibodies together, IgG antibodies were found in 9/84 (10.7%) and IgM in 15/84 (17.9%) patients. There was no correlation between age, gender, site of onset or survival and anti-ganglioside-positive/-negative titres in ALS-patients. No statistically significant difference in the frequency of anti-ganglioside antibodies compared to the group of healthy blood donors was found.

Conclusion

Even with this more comprehensive approach, anti-ganglioside antibody frequencies and patterns in our ALS cohort closely resembled the values measured in healthy controls. In accordance with other studies, we did not observe any association of a distinct ALS phenotype with elevated anti-ganglioside antibodies or an impact on survival.     

Amyotrophic Lateral Sclerosis and Skeletal Muscle: An Update

Amyotrophic lateral sclerosis (ALS) is the most frequent adult-onset motor neuron disease characterized by degeneration of upper and lower motor neurons (MNs), generalized weakness and muscle atrophy. The “neurocentric” view of ALS assumes that the disease primarily affects motor neurons, while muscle alterations only represent a consequence, in the periphery, of motor neuron loss. However, this outlook was recently challenged by evidence suggesting that non-neural cells such as microglia, astrocytes, peripheral blood mononuclear cells (PBMCs) and skeletal muscle fibres participate in triggering motor neuron degeneration, and this stressed the concept that alterations in different cell types may act together to exacerbate the disease. In this review, we will summarize the most recent findings on the alterations of skeletal muscle fibres found in ALS, with particular attention to the relationship between mutant SOD1 and skeletal muscle. We will analyze changes in muscle function, in the expression of myogenic regulatory factors, and also mitochondrial dysfunction, SOD1 aggregation and proteasome activity.     

DREAM-Dependent Activation of Astrocytes in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease of unknown origin and characterized by a relentless loss of motor neurons that causes a progressive muscle weakness until death. Among the several pathogenic mechanisms that have been related to ALS, a dysregulation of calcium-buffering proteins in motor neurons of the brain and spinal cord can make these neurons more vulnerable to disease progression. Downstream regulatory element antagonist modulator (DREAM) is a neuronal calcium-binding protein that plays multiple roles in the nucleus and cytosol. The main aim of this study was focused on the characterization of DREAM and glial fibrillary acid protein (GFAP) in the brain and spinal cord tissues from transgenic SOD1^G93A mice and ALS patients to unravel its potential role under neurodegenerative conditions. The DREAM and GFAP levels in the spinal cord and different brain areas from transgenic SOD1^G93A mice and ALS patients were analyzed by Western blot and immunohistochemistry. Our findings suggest that the calcium-dependent excitotoxicity progressively enhanced in the CNS in ALS could modulate the multifunctional nature of DREAM, strengthening its apoptotic way of action in both motor neurons and astrocytes, which could act as an additional factor to increase neuronal damage. The direct crosstalk between astrocytes and motor neurons can become vulnerable under neurodegenerative conditions, and DREAM could act as an additional switch to enhance motor neuron loss. Together, these findings could pave the way to further study the molecular targets of DREAM to find novel therapeutic strategies to fight ALS.     

Anti-Sulfoglucuronosyl Paragloboside Antibody: A Potential Serologic Marker of Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by progressive degeneration of upper and lower motor neurons. Although the etiology of ALS is obscure, genetic studies of familiar ALS suggest a multifactorial etiology for this condition. Similarly, there probably are multiple causes for sporadic ALS. Autoimmune-mediated motor neuron dysfunction is one proposed etiology for sporadic ALS. In the present study, anti-glycolipid antibodies including GM1, GD1b, GD3, and sulfoglucuronosyl paragloboside (SGPG) were investigated in the sera of a large number of patient samples, including 113 ALS patients and 50 healthy controls, by means of enzyme-linked immunosorbent assay with affinity parametric complex criterion evaluation and thin-layer chromatography immunooverlay (immuno-TLC). Anti-SGPG antibodies were found in the sera of 13.3% ALS patients (15 out of 113). The highest titer reached 1:1600. The presence of anti-SGPG antibodies in the serum samples was also confirmed by immuno-TLC. Importantly, a multiple logistic regression analysis showed that the presence of anti-SGPG antibody was positively correlated with age (p < .01) and negatively correlated with ALS Functional Rating Scale score (p < .05). Moreover, the localization of SGPG-immunoreactivity on the motor neurons of rat spinal cord and a mouse motor neuronal cell line, NSC-34 was observed by an immunofluorescence method. These data suggest that SGPG could represent a specific pathogenic antigen in those ALS patients. The presence of anti-SGPG antibodies in the serum of ALS patients should represent a diagnostic biomarker of ALS, and it could reflect the severity of the disease.     

Defective Neurofilament Transport in Mouse Models of Amyotrophic Lateral Sclerosis: A Review

Neurofilament proteins synthesized in the cell body of neurons are assembled and transported into axons, where they influence axon radial growth, axonal transport, and nerve conduction velocities. In diseased states, neurofilaments accumulate in cell bodies and proximal axons of affected neurons, and these lesions are characteristic of many neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD), spinal muscular atrophy (SMA), Charcot-Marie-Tooth disease type 2 (CMT2), and hereditary sensory motor neuropathy. Although the molecular mechanisms that contribute to these accumulations are not yet identified, transgenic mouse models are beginning to provide insight into the role of neurofilament transport in disease-related dysfunction of neurons. This review addresses axonal transport in mouse models of ALS and the special significance of neurofilament transport in this disease.     

肌萎缩性侧索硬化症动物模型的应用进展

肌萎缩性侧索硬化症（ALS）是运动神经元选择性死亡而导致运动功能障碍的神经性疾病,是成年人运动神经元病中最常见的疾病。已有很多学说讨论其发病机制,并且建立了ALS动物模型。随着现代生物学的发展和不同学科间的相互渗入,各种治疗策略在ALS模型实验中得到实践并有望用于临床。简要综述了ALS治疗方法在转基因动物模型中的研究进展。     

Cortical Thinning and Clinical Heterogeneity in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) has heterogeneous clinical features that could be translated into specific patterns of brain atrophy. In the current study we have evaluated the relationship between different clinical expressions of classical ALS and measurements of brain cortical thickness. Cortical thickness analysis was conducted from 3D-MRI using FreeSurfer software in 29 ALS patients and 20 healthy controls. We explored three clinical traits of the disease, subdividing the patients into two groups for each of them: the bulbar or spinal onset, the higher or lower upper motor neuron burden, the faster or slower disease progression. We used both a whole brain vertex-wise analysis and a ROI analysis on primary motor areas. ALS patients showed cortical thinning in bilateral precentral gyrus, bilateral middle frontal gyrus, right superior temporal gyrus and right occipital cortex. ALS patients with higher upper motor neuron burden showed a significant cortical thinning in the right precentral gyrus and in other frontal extra-motor areas, compared to healthy controls. ALS patients with spinal onset showed a significant cortical thinning in the right precentral gyrus and paracentral lobule, compared to healthy controls. ALS patients with faster progressive disease showed a significant cortical thinning in widespread bilateral frontal and temporal areas, including the bilateral precentral gyrus, compared to healthy controls. Focusing on the primary motor areas, the ROI analysis revealed that the mean cortical thickness values were significantly reduced in ALS patients with higher upper motor neuron burden, spinal onset and faster disease progression related to healthy controls. In conclusion, the thickness of primary motor cortex could be a useful surrogate marker of upper motor neuron involvement in ALS; also our results suggest that cortical thinning in motor and non motor areas seem to reflect the clinical heterogeneity of the disease.     

Adipose Tissue Distribution Predicts Survival in Amyotrophic Lateral Sclerosis

Background

amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that leads to death within a few years after diagnosis. Malnutrition and weight loss are frequent and are indexes of poor prognosis. Total body fat and fat distribution have not been studied in ALS patients.

Objectives

Our aim was to describe adipose tissue content and distribution in ALS patients.

Design

We performed a cross-sectional study in a group of ALS patients (n = 62, mean disease duration 22 months) along with age and gender matched healthy controls (n = 62) using a MRI-based method to study quantitatively the fat distribution.

Results

Total body fat of ALS patients was not changed as compared with controls. However, ALS patients displayed increased visceral fat and an increased ratio of visceral to subcutaneous fat. Visceral fat was not correlated with clinical severity as judged using the ALS functional rating scale (ALS-FRS-R), while subcutaneous fat in ALS patients correlated positively with ALS-FRS-R and disease progression. Multiple regression analysis showed that gender and ALS-FRS-R, but not site of onset, were significant predictors of total and subcutaneous fat. Increased subcutaneous fat predicted survival in male patients but not in female patients (p<0.05).

Conclusions

Fat distribution is altered in ALS patients, with increased visceral fat as compared with healthy controls. Subcutaneous fat content is a predictor of survival of ALS patients.     

Molecular Imaging of Microglial Activation in Amyotrophic Lateral Sclerosis

There is growing evidence of activated microglia and inflammatory processes in the cerebral cortex in amyotrophic lateral sclerosis (ALS). Activated microglia is characterized by increased expression of the 18 kDa translocator protein (TSPO) in the brain and may be a useful biomarker of inflammation. In this study, we evaluated neuroinflammation in ALS patients using a radioligand of TSPO, ¹⁸F-DPA-714. Ten patients with probable or definite ALS (all right-handed, without dementia, and untreated by riluzole or other medication that might bias the binding on the TSPO), were enrolled prospectively and eight healthy controls matched for age underwent a PET study. Comparison of the distribution volume ratios between both groups were performed using a Mann-Whitney’s test. Significant increase of distribution of volume ratios values corresponding to microglial activation was found in the ALS sample in primary motor, supplementary motor and temporal cortex (p = 0.009, p = 0.001 and p = 0.004, respectively). These results suggested that the cortical uptake of ¹⁸F-DPA-714 was increased in ALS patients during the “time of diagnosis” phase of the disease. This finding might improve our understanding of the pathophysiology of ALS and might be a surrogate marker of efficacy of treatment on microglial activation.     

Myostatin as a therapeutic target in Amyotrophic Lateral Sclerosis

Amyotrophic Lateral Sclerosis is a devastating neurological disease that is inevitably fatal after 3–5 years duration. Treatment options are minimal and as such new therapeutic modalities are required. In this review, we discuss the role of the myostatin pathway as a modulator of skeletal muscle mass and therapeutic approaches using biological based therapies. Both monoclonal antibodies to myostatin and a soluble receptor decoy to its high affinity receptor have been used in clinical trials of neuromuscular diseases and while there have been efficacy signals with the latter approach there have also been safety issues. Our approach is to target the high affinity receptor-binding site on myostatin and to develop a next generation set of therapeutic reagents built on a novel protein scaffold. This is the natural single domain VNAR found in sharks which is extremely versatile and has the ability to develop products with superior properties compared to existing therapeutics.     

Superoxide Dismutase Concentration and Activity in Familial Amyotrophic Lateral Sclerosis

Abstract: Some cases of autosomal-dominant familial amyotrophic lateral sclerosis (FALS) have been associated with mutations in SOD1 , the gene that encodes Cu/Zn superoxide dismutase (Cu/Zn SOD). We determined the concentrations (µg of Cu/Zn SOD/mg of total protein), specific activities (U/µg of total protein), and apparent turnover numbers (U/µmol of Cu/Zn SOD) of Cu/Zn SOD in erythrocyte lysates from patients with known SOD1 mutations. We also measured the concentrations and activities of Cu/Zn SOD in FALS patients with no identifiable SOD1 mutations, sporadic ALS (SALS) patients, and patients with other neurologic disorders. The concentration and specific activity of Cu/Zn SOD were decreased in all patients with SOD1 mutations, with mean reductions of 51 and 46%, respectively, relative to controls. In contrast, the apparent turnover number of the enzyme was not altered in these patients. For the six mutations studied, there was no correlation between enzyme concentration or specific activity and disease severity, expressed as either duration of disease or age of onset. No significant alterations in the concentration, specific activity, or apparent turnover number of Cu/Zn SOD were detected in the FALS patients with no identifiable SOD1 mutations, SALS patients, or patients with other neurologic disorders. That Cu/Zn SOD concentration and specific activity are equivalently reduced in erythrocytes from patients with SOD1 mutations suggests that mutant Cu/Zn SOD is unstable in these cells. That concentration and specific activity do not correlate with disease severity suggests that an altered, novel function of the enzyme, rather than reduction of its dismutase activity, may be responsible for the pathogenesis of FALS.     

Alsin and the Molecular Pathways of Amyotrophic Lateral Sclerosis

Autosomal recessive mutations in the ALS2 gene lead to a clinical spectrum of motor dysfunction including juvenile onset amyotrophic lateral sclerosis (ALS2), primary lateral sclerosis, and hereditary spastic paraplegia. The 184-kDa alsin protein, encoded by the full-length ALS2 gene, contains three different guanine-nucleotide-exchange factor-like domains, which may play a role in the etiology of the disease. Multiple in vitro biochemical and cell biology assays suggest that alsin dysfunction affects endosome trafficking through a Rab5 small GTPase family-mediated mechanism. Four ALS2-deficient mouse models have been generated by different groups and used to study the behavioral and pathological impact of alsin deficiency. These mouse models largely fail to recapitulate hallmarks of motor neuron disease, but the subtle deficits that are observed in behavior and pathology have aided in our understanding of the relationship between alsin and motor dysfunction. In this review, we summarize recent clinical and molecular reports regarding alsin and attempt to place these results within the larger context of motor neuron disease.     

Targeted Exon Capture and Sequencing in Sporadic Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease that results in progressive degeneration of motor neurons, ultimately leading to paralysis and death. Approximately 10% of ALS cases are familial, with the remaining 90% of cases being sporadic. Genetic studies in familial cases of ALS have been extremely informative in determining the causative mutations behind ALS, especially as the same mutations identified in familial ALS can also cause sporadic disease. However, the cause of ALS in approximately 30% of familial cases and in the majority of sporadic cases remains unknown. Sporadic ALS cases represent an underutilized resource for genetic information about ALS; therefore, we undertook a targeted sequencing approach of 169 known and candidate ALS disease genes in 242 sporadic ALS cases and 129 matched controls to try to identify novel variants linked to ALS. We found a significant enrichment in novel and rare variants in cases versus controls, indicating that we are likely identifying disease associated mutations. This study highlights the utility of next generation sequencing techniques combined with functional studies and rare variant analysis tools to provide insight into the genetic etiology of a heterogeneous sporadic disease.     

Cognitive Impairment in Chinese Patients with Sporadic Amyotrophic Lateral Sclerosis

Background

It has reached a consensus that patients with amyotrophic lateral sclerosis (ALS) could display cognitive impairment characterized by executive dysfunction or even dementia, but cognitive spectrum of Chinese patients with ALS still waits to be documented.

Methods

A total of 106 incident patients with sporadic ALS were enrolled and comprehensive neuropsychological tests covering memory, executive function, attention, language, and visuospatial function were administered to them. Neuropsychological performances of 76 age- and education- matched healthy controls were used for the purpose of classification and comparison.

Results

106 patients were categorized into 4 subtypes:84 (79.2%) ALS with normal cognition (ALS-NC), 12 (11.3%) ALS with executive cognitive impairment (ALS-ECI), 5 (4.7%) ALS with non-executive cognitive impairment (ALS-NECI), and 5 (4.7%) ALS with frontotemporal lobe degeneration (ALS-FTLD). Under the same criteria, 2 (2.6%) and 1 (1.3%) healthy controls were diagnosed as ECI and NECI, respectively. The proportion of ECI was significantly higher in non-demented ALS than that in healthy controls, but it was not for NECI. Patients with ALS-FTLD had significantly severer bulbar function and older age than those with ALS-NC.

Conclusion

Comorbid FTLD occurred in around 5% of Chinese sporadic ALS cases. Different genetic background and unique age distribution of Chinese ALS patients might be the reasons for the relatively low rate of comorbid FTLD. Cognitive dysfunction, predominant but not exclusive in executive area, was present in around 16% of non-demented ALS patients.     

AMPK Signalling and Defective Energy Metabolism in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is caused by selective loss of upper and lower motor neurons by complex mechanisms that are incompletely understood. Motor neurons are large, highly polarised and excitable cells with unusually high energetic demands to maintain resting membrane potential and propagate action potentials. This leads to higher ATP consumption and mitochondrial metabolism in motor neurons relative to other cells. Here, we review increasing evidence that defective energy metabolism and homeostasis contributes to selective vulnerability and degeneration of motor neurons in ALS. Firstly, we provide a brief overview of major energetic pathways in the CNS, including glycolysis, oxidative phosphorylation and the AMP-activated protein kinase (AMPK) signalling pathway, while highlighting critical metabolic interactions between neurons and astrocytes. Next, we review evidence from ALS patients and transgenic mutant SOD1 mice for weight loss, hypermetabolism, hyperlipidemia and mitochondrial dysfunction in disease onset and progression. Genetic and therapeutic modifiers of energy metabolism in mutant SOD1 mice will also be summarised. We also present evidence that additional ALS-linked proteins, TDP-43 and FUS, lead to energy disruption and mitochondrial defects in motor neurons. Lastly, we review emerging evidence including our own that dysregulation of the AMPK signalling cascade in motor neurons is an early and common event in ALS pathogenesis. We suggest that an imbalance in energy metabolism should be considered an important factor in both progression and potential treatment of ALS.