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Amyotrophic lateral sclerosis is a typically rapidly progressive neurodegenerative disorder affecting motor neurons leading to progressive muscle paralysis and death, usually from respiratory failure, in 3-5 years. Some patients have slow disease progression and prolonged survival, but the underlying mechanisms remain poorly understood. Riluzole, the only approved treatment, only modestly prolongs survival and has no effect on muscle function. In the early phase of the disease, motor neuron loss is initially compensated for by collateral reinnervation, but over time this compensation fails, leading to progressive muscle wasting. The crucial role of muscle histone deacetylase 4 and its regulator microRNA-206 in compensatory reinnervation and disease progression was recently suggested in a mouse model of amyotrophic lateral sclerosis (transgenic mice carrying human mutations in the superoxide dismutase gene). Here, we sought to investigate whether the microRNA-206-histone deacetylase 4 pathway plays a role in muscle compensatory reinnervation in patients with amyotrophic lateral sclerosis and thus contributes to disease outcome differences. We studied muscle reinnervation using high-resolution confocal imaging of neuromuscular junctions in muscle samples obtained from 11 patients with amyotrophic lateral sclerosis, including five long-term survivors. We showed that the proportion of reinnervated neuromuscular junctions was significantly higher in long-term survivors than in patients with rapidly progressive disease. We analysed the expression of muscle candidate genes involved in the reinnervation process and showed that histone deacetylase 4 upregulation was significantly greater in patients with rapidly progressive disease and was negatively correlated with the extent of muscle reinnervation and functional outcome. Conversely, the proposed regulator of histone deacetylase 4, microRNA-206, was upregulated in both patient groups, but did not correlate with disease progression or reinnervation. We conclude that muscle expression of histone deacetylase 4 may be a key factor for muscle reinnervation and disease progression in patients with amyotrophic lateral sclerosis. Specific histone deacetylase 4 inhibitors may then constitute a therapeutic approach to enhancing motor performance and slowing disease progression in amyotrophic lateral sclerosis.

The dihydropyrimidinase-like 3 (DPYSL3) or Collapsin Response Mediator Protein 4a (CRMP4a) expression is modified in neurodegeneration and is involved in several ALS-associated pathways including axonal transport, glutamate excitotoxicity, and oxidative stress. The objective of the study was to analyze CRMP4 as a risk factor for ALS. We analyzed the DPYSL3/CRMP4 gene in French ALS patients (n = 468) and matched-controls (n = 394). We subsequently examined a variant in a Swedish population (184 SALS, 186 controls), and evaluated its functional effects on axonal growth and survival in motor neuron cell culture. The rs147541241:A>G missense mutation occurred in higher frequency among French ALS patients (odds ratio = 2.99) but the association was not confirmed in the Swedish population. In vitro expression of mutated DPYSL3 in motor neurons reduced axonal growth and accelerated cell death compared with wild type protein. Thus, the association between the rs147541241 variant and ALS was limited to the French population, highlighting the geographic particularities of genetic influences (risks, contributors). The identified variant appears to shorten motor neuron survival through a detrimental effect on axonal growth and CRMP4 could act as a key unifier in transduction pathways leading to neurodegeneration through effects on early axon development., (© 2013 WILEY PERIODICALS, INC.)

Our objective was to demonstrate that ALS patients have sensory pathway involvement and that local cord atrophy reflects segmental lower motor neuron involvement. Twenty-nine ALS patients with spinal onset and twenty-one healthy controls were recruited. Diffusion tensor imaging (DTI), magnetization transfer and atrophy index were measured in the spinal cord, complemented with transcranial magnetic stimulations. Metrics were quantified within the lateral corticospinal and the dorsal segments of the cervical cord. Significant differences were detected between patients and controls for DTI and magnetization transfer metrics in the lateral and dorsal segments of the spinal cord. Fractional anisotropy correlated with ALSFRS-R (p = 0.04) and motor threshold (p = 0.02). Stepwise linear regression detected local spinal cord atrophy associated with weakness in the corresponding muscle territory, i.e. C4 level for deltoid and C7 level for hand muscles. In conclusion, impairment of spinal sensory pathways was detected at an early stage of the disease. Our data also demonstrate an association between muscle deficits and local spinal cord atrophy, suggesting that atrophy is a sensitive biomarker for lower motor neurons degeneration.

Amyotrophic lateral sclerosis (ALS) is an adult onset, progressive and fatal motor neuron degenerative disease [1]. The aetiology of ALS is currently unknown, though strongly suggested to be multifactorial. Recently, the kynurenine pathway (KP) has emerged as a potential contributing factor [2]. The KP is a major route for the metabolism of tryptophan, generating neuroactive intermediates in the process. These catabolites include the excitotoxic N-methyl-D-aspartate (NMDA) receptor agonist, quinolinic acid (QUIN) [3] and the neuroprotective NMDA receptor antagonist, kynurenic acid (KYNA) [4,5]. These catabolites appear to play a key role in the communication between the nervous and immune systems, and also in modulating cell proliferation and tissue function [6]. As the cause of ALS is still unknown, there is presently no efficient treatment for it. Currently, Riluzole is the drug of choice but its effect is relatively modest [7]. Targeting the KP, hence, could offer a new therapeutic option to improve ALS treatment [8]. Several drugs that block the KP are already under investigation by our laboratory and others, some of which are in or about to enter clinical trials for other diseases. For example, the KP inhibitors, Teriflunomide (Sanofi-Aventis) and Laquinimod (Teva Neuroscience). Recently, a KP inhibitor has also reached the Japan market as an immunomodulative drug [9]: Tranilast/Rizaben (Angiogen Ltd.) is an anthranilic acid derivative [8]. Finally, the 8-hydroxyquinolinine metal attenuating compounds, Clioquinol and PBT2, interestingly have close structural similarity with KYNA and QUIN. Such drugs would open a new and important therapeutic door for ALS.

Amyotrophic lateral sclerosis (ALS) is the most frequent adult-onset motor neuron disease characterized by degeneration of upper and lower motor neurons, generalized weakness and muscle atrophy. Most cases of ALS appear sporadically but some forms of the disease result from mutations in the gene encoding the antioxidant enzyme Cu/Zn superoxide dismutase (SOD1). Several other mutated genes have also been found to predispose to ALS including, among others, one that encodes the regulator of axonal retrograde transport dynactin. As all roads lead to the proverbial Rome, we discuss here how distinct molecular pathways may converge to the same final result that is motor neuron death. We critically review the basic research on SOD1-linked ALS to propose a pioneering model of a 'systemic' form of the disease, causally involving multiple cell types, either neuronal or non-neuronal. Contrasting this, we also postulate that other neuron-specific defects, as those triggered by dynactin dysfunction, may account for a primary motor neuron disease that would represent 'pure' neuronal forms of ALS. Identifying different disease subtypes is an unavoidable step toward the understanding of the physiopathology of ALS and will hopefully help to design specific treatments for each subset of patients.

Amyotrophic lateral sclerosis (ALS) is a progressive, neurodegenerative disease characterized by loss of upper and lower motor neurons. ALS is considered to be a complex trait and genome-wide association studies (GWAS) have implicated a few susceptibility loci. However, many more causal loci remain to be discovered. Since it has been shown that genetic variants associated with complex traits are more likely to be eQTLs than frequency-matched variants from GWAS platforms, we conducted a two-stage genome-wide screening for eQTLs associated with ALS. In addition, we applied an eQTL analysis to finemap association loci. Expression profiles using peripheral blood of 323 sporadic ALS patients and 413 controls were mapped to genome-wide genotyping data. Subsequently, data from a two-stage GWAS (3,568 patients and 10,163 controls) were used to prioritize eQTLs identified in the first stage (162 ALS, 207 controls). These prioritized eQTLs were carried forward to the second sample with both gene-expression and genotyping data (161 ALS, 206 controls). Replicated eQTL SNPs were then tested for association in the second-stage GWAS data to find SNPs associated with disease, that survived correction for multiple testing. We thus identified twelve cis eQTLs with nominally significant associations in the second-stage GWAS data. Eight SNP-transcript pairs of highest significance (lowest p = 1.27 × 10(-51)) withstood multiple-testing correction in the second stage and modulated CYP27A1 gene expression. Additionally, we show that C9orf72 appears to be the only gene in the 9p21.2 locus that is regulated in cis, showing the potential of this approach in identifying causative genes in association loci in ALS. This study has identified candidate genes for sporadic ALS, most notably CYP27A1. Mutations in CYP27A1 are causal to cerebrotendinous xanthomatosis which can present as a clinical mimic of ALS with progressive upper motor neuron loss, making it a plausible susceptibility gene for ALS.

Mutations in profilin 1 (PFN1) have been identified in rare familial cases of Amyotrophic Lateral Sclerosis (ALS). PFN1 is involved in multiple pathways that could intervene in ALS pathology. However, the specific pathogenic role of PFN1 mutations in ALS is still not fully understood. We hypothesized that PFN1 could play a role in regulating autophagy pathways and that PFN1 mutations could disrupt this function. We used patient cells (lymphoblasts) or tissue (post-mortem) carrying PFN1 mutations (M114T and E117G), and designed experimental models expressing wild-type or mutant PFN1 (cell lines and novel PFN1 mice established by lentiviral transgenesis) to study the effects of PFN1 mutations on autophagic pathway markers. We observed no accumulation of PFN1 in the spinal cord of one E117G mutation carrier. Moreover, in patient lymphoblasts and transfected cell lines, the M114T mutant PFN1 protein was unstable and deregulated the RAB9-mediated alternative autophagy pathway involved in the clearance of damaged mitochondria. In vivo, motor neurons expressing M114T mutant PFN1 showed mitochondrial abnormalities. Our results demonstrate that the M114T PFN1 mutation is more deleterious than the E117G variant in patient cells and experimental models and suggest a role for the RAB9-dependent autophagic pathway in ALS. [ABSTRACT FROM AUTHOR]

Purpose: The mechanisms underlying the topography of motor deficits in spinal muscular atrophy (SMA) remain unknown. We investigated the profile of spinal cord atrophy (SCA) in SMN1-linked SMA, and its correlation with the topography of muscle weakness. Materials and Methods: Eighteen SMN1-linked SMA patients type III/V and 18 age/gender-matched healthy volunteers were included. Patients were scored on manual muscle testing and functional scales. Spinal cord was imaged using 3T MRI system. Radial distance (RD) and cord cross-sectional area (CSA) measurements in SMA patients were compared to those in controls and correlated with strength and disability scores. Results: CSA measurements revealed a significant cord atrophy gradient mainly located between C3 and C6 vertebral levels with a SCA rate ranging from 5.4% to 23% in SMA patients compared to controls. RD was significantly lower in SMA patients compared to controls in the anterior-posterior direction with a maximum along C4 and C5 vertebral levels (p-values < 10−5). There were no correlations between atrophy measurements, strength and disability scores. Conclusions: Spinal cord atrophy in adult SMN1-linked SMA predominates in the segments innervating the proximal muscles. Additional factors such as neuromuscular junction or intrinsic skeletal muscle defects may play a role in more complex mechanisms underlying weakness in these patients. [ABSTRACT FROM AUTHOR]

Amyotrophic lateral sclerosis is a typically rapidly progressive neurodegenerative disorder affecting motor neurons leading to progressive muscle paralysis and death, usually from respiratory failure, in 3–5 years. Some patients have slow disease progression and prolonged survival, but the underlying mechanisms remain poorly understood. Riluzole, the only approved treatment, only modestly prolongs survival and has no effect on muscle function. In the early phase of the disease, motor neuron loss is initially compensated for by collateral reinnervation, but over time this compensation fails, leading to progressive muscle wasting. The crucial role of muscle histone deacetylase 4 and its regulator microRNA-206 in compensatory reinnervation and disease progression was recently suggested in a mouse model of amyotrophic lateral sclerosis (transgenic mice carrying human mutations in the superoxide dismutase gene). Here, we sought to investigate whether the microRNA-206–histone deacetylase 4 pathway plays a role in muscle compensatory reinnervation in patients with amyotrophic lateral sclerosis and thus contributes to disease outcome differences. We studied muscle reinnervation using high-resolution confocal imaging of neuromuscular junctions in muscle samples obtained from 11 patients with amyotrophic lateral sclerosis, including five long-term survivors. We showed that the proportion of reinnervated neuromuscular junctions was significantly higher in long-term survivors than in patients with rapidly progressive disease. We analysed the expression of muscle candidate genes involved in the reinnervation process and showed that histone deacetylase 4 upregulation was significantly greater in patients with rapidly progressive disease and was negatively correlated with the extent of muscle reinnervation and functional outcome. Conversely, the proposed regulator of histone deacetylase 4, microRNA-206, was upregulated in both patient groups, but did not correlate with disease progression or reinnervation. We conclude that muscle expression of histone deacetylase 4 may be a key factor for muscle reinnervation and disease progression in patients with amyotrophic lateral sclerosis. Specific histone deacetylase 4 inhibitors may then constitute a therapeutic approach to enhancing motor performance and slowing disease progression in amyotrophic lateral sclerosis. [ABSTRACT FROM AUTHOR]

Mutations in SQSTM1 encoding the sequestosome 1/p62 protein have recently been identified in familial and sporadic cases of amyotrophic lateral sclerosis (ALS). p62 is a component of the ubiquitin inclusions detected in degenerating neurons in ALS patients. We sequenced SQSTM1 in 90 French patients with familial ALS (FALS) and 74 autopsied ALS cases with sporadic ALS (SALS). We identified, at the heterozygote state, one missense c.1175C>T, p.Pro392Leu (exon 8) in one of our FALS and one substitution in intron 7 (the c.1165+1G>A, previously called IVS7+1 G-A, A390X) affecting the exon 7 splicing site in one SALS. These mutations that are located in the ubiquitin-associated domain (UBA domain) of the p62 protein have already been described in Paget's disease and ALS patients carrying these mutations had both concomitant Paget's disease. However, we also identified two novel missense mutations in two SALS: the c.259A>G, p.Met87Val in exon 2 and the c.304A>G, p.Lys102Glu in exon 3. These mutations that were not detected in 360 control subjects are possibly pathogenic. Neuropathology analysis of three patients carrying SQSTM1 variants revealed the presence of large round p62 inclusions in motor neurons, and immunoblot analysis showed an increased p62 and TDP-43 protein levels in the spinal cord. Our results confirm that SQSTM1 gene mutations could be the cause or genetic susceptibility factor of ALS in some patients. [ABSTRACT FROM AUTHOR]

Spasticity is a common and disabling symptom observed in patients with central nervous system diseases, including amyotrophic lateral sclerosis, a disease affecting both upper and lower motor neurons. In amyotrophic lateral sclerosis, spasticity is traditionally thought to be the result of degeneration of the upper motor neurons in the cerebral cortex, although degeneration of other neuronal types, in particular serotonergic neurons, might also represent a cause of spasticity. We performed a pathology study in seven patients with amyotrophic lateral sclerosis and six control subjects and observed that central serotonergic neurons suffer from a degenerative process with prominent neuritic degeneration, and sometimes loss of cell bodies in patients with amyotrophic lateral sclerosis. Moreover, distal serotonergic projections to spinal cord motor neurons and hippocampus systematically degenerated in patients with amyotrophic lateral sclerosis. In SOD1 (G86R) mice, a transgenic model of amyotrophic lateral sclerosis, serotonin levels were decreased in brainstem and spinal cord before onset of motor symptoms. Furthermore, there was noticeable atrophy of serotonin neuronal cell bodies along with neuritic degeneration at disease onset. We hypothesized that degeneration of serotonergic neurons could underlie spasticity in amyotrophic lateral sclerosis and investigated this hypothesis in vivo using tail muscle spastic-like contractions in response to mechanical stimulation as a measure of spasticity. In SOD1 (G86R) mice, tail muscle spastic-like contractions were observed at end-stage. Importantly, they were abolished by 5-hydroxytryptamine-2b/c receptors inverse agonists. In line with this, 5-hydroxytryptamine-2b receptor expression was strongly increased at disease onset. In all, we show that serotonergic neurons degenerate during amyotrophic lateral sclerosis, and that this might underlie spasticity in mice. Further research is needed to determine whether inverse agonists of 5-hydroxytryptamine-2b/c receptors could be of interest in treating spasticity in patients with amyotrophic lateral sclerosis. [ABSTRACT FROM AUTHOR]

Amyotrophic lateral sclerosis (ALS) is a progressive and fatal motor neuron disease of unknown pathogenesis. The kynurenine pathway (KP), activated during neuroinflammation, is emerging as a possible contributory factor in ALS. The KP is the major route for tryptophan (TRP) catabolism. The intermediates generated can be either neurotoxic, such as quinolinic acid (QUIN), or neuroprotective, such as picolinic acid (PIC), an important endogenous chelator. The first and inducible enzyme of the pathway is indoleamine 2,3-dioxygenase (IDO). The present study aimed to characterize the expression of the KP in cerebrospinal fluid (CSF), serum and central nervous system (CNS) tissue of ALS patients. Using high performance liquid chromatography, we analysed the levels of TRP and kynurenine (KYN), and, with gas chromatography/mass spectrometry, the levels of PIC and QUIN, in the CSF and serum of ALS patients and control subjects. Immunohistochemistry was employed to determine the expression of QUIN, IDO and human leukocyte antigen-DR (HLA-DR) in sections of brain and spinal cord from ALS patients. There were significantly increased levels of CSF and serum TRP ( P < 0.0001), KYN ( P < 0.0001) and QUIN ( P < 0.05) and decreased levels of serum PIC ( P < 0.05) in ALS samples. There was a significant increase in activated microglia expressing HLA-DR ( P < 0.0001) and increased neuronal and microglial expression of IDO and QUIN in ALS motor cortex and spinal cord. We show the presence of neuroinflammation in ALS and provide the first strong evidence for the involvement of the KP in ALS. These data point to an inflammation-driven excitotoxic-chelation defective mechanism in ALS, which may be amenable to inhibitors of the KP. [ABSTRACT FROM AUTHOR]

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease affecting the motor neurons, in both the spinal cord and medulla (lower motor neurons) and cerebral cortex (upper motor neurons). Even though ALS remains fatal, several advances have been made during the last decade in improving the consequences of motor dysfunction, quality of life and survival time of patients. Treatment of ALS cannot be restricted to riluzole, the only molecule that has been proved to modify the evolution of the disease. Symptomatic treatments have an important role in controlling the major consequences of the disease, such as pain, sleep disorders, spasticity, hypersialhorroea, emotional lability, depression and digestive disorders (constipation and reflux). All these symptoms need to be recognized and their possible causes identified in order to provide the most appropriate management of patients with ALS. However, an advance in the daily care of patients is the identification of two important phenomena that occur during the evolution of the disease: swallowing difficulties and the occurrence of diaphragmatic dysfunction. For both, specific medical interventions have been developed to allow correction of the consequences (i.e. weight loss and respiratory insufficiency). Although no controlled trials have been performed, observational studies suggest that gastrostomy and non-invasive ventilation may improve at least quality of life and survival. All of these various approaches, pharmaceutical and non-pharmaceutical therapies, are prescribed according to individual symptoms and require the involvement of a large range of health professionals. This multidisciplinary approach in ALS clinics is considered to be one of the more important factors impacting on survival rate and appears to be the gold standard of medical care of ALS patients. Important findings have been made in understanding the nature of the degenerative process that affects the motor neurons. All these data have allowed new therapeutic molecules to be tested alone or in combination with riluzole. Despite the negative results obtained until now, we hope to demonstrate very soon a greater improvement in therapy. [ABSTRACT FROM AUTHOR]

A transgenic animal model for anterior horn cell loss was established in 1994. This model is based on the insertion of a high copy number of disease-causing human Cu/Zn SOD mutations into the intact mouse genome. It serves to establish hypotheses for the pathogenesis of anterior horn cell death, but also to test potential pharmacological approaches to therapy in human ALS. Today, more than 100 - published and unpublished - compounds have been tested in this animal model, a large part of them being reported as successful. However, it proved to be difficult to translate these therapeutic successes in the animal model into human trials. Also, a number of disease-modifying strategies were difficult to reproduce, even by the same group. On the other hand, the step from mice to men means a huge investment for the sponsors of clinical trials and the scientific community. Therefore, establishment of standard methods for drug testing in ALS models is mandatory. In this workshop, clinical and preclinical researchers established in the field of ALS/MND met in Holland in March 2006 in order to establish guidelines for the community for drug testing in mouse models. [ABSTRACT FROM AUTHOR]

Recently, TDP-43 was identified as a key component of ubiquitinated aggregates in amyotrophic lateral sclerosis (ALS), an adult-onset neurological disorder that leads to the degeneration of motor neurons. Here we report eight missense mutations in nine individuals—six from individuals with sporadic ALS (SALS) and three from those with familial ALS (FALS)—and a concurring increase of a smaller TDP-43 product. These findings further corroborate that TDP-43 is involved in ALS pathogenesis. [ABSTRACT FROM AUTHOR]