Mechanisms Of Amyotrophic Lateral Sclerosis Research Articles

A Mouse Model of Familial ALS Has Increased CNS Levels of Endogenous Ubiquinol9/10 and Does Not Benefit from Exogenous Administration of Ubiquinol10

Oxidative stress and mitochondrial impairment are the main pathogenic mechanisms of Amyotrophic Lateral Sclerosis (ALS), a severe neurodegenerative disease still lacking of effective therapy. Recently, the coenzyme-Q (CoQ) complex, a key component of mitochondrial function and redox-state modulator, has raised interest for ALS treatment. However, while the oxidized form ubiquinone10 was ineffective in ALS patients and modestly effective in mouse models of ALS, no evidence was reported on the effect of the reduced form ubiquinol10, which has better bioavailability and antioxidant properties. In this study we compared the effects of ubiquinone10 and a new stabilized formulation of ubiquinol10 on the disease course of SOD1G93A transgenic mice, an experimental model of fALS. Chronic treatments (800 mg/kg/day orally) started from the onset of disease until death, to mimic the clinical trials that only include patients with definite ALS symptoms. Although the plasma levels of CoQ10 were significantly increased by both treatments (from <0.20 to 3.0–3.4 µg/mL), no effect was found on the disease progression and survival of SOD1G93A mice. The levels of CoQ10 in the brain and spinal cord of ubiquinone10- or ubiquinol10-treated mice were only slightly higher (≤10%) than the endogenous levels in vehicle-treated mice, indicating poor CNS availability after oral dosing and possibly explaining the lack of pharmacological effects. To further examine this issue, we measured the oxidized and reduced forms of CoQ9/10 in the plasma, brain and spinal cord of symptomatic SOD1G93A mice, in comparison with age-matched SOD1WT. Levels of ubiquinol9/10, but not ubiquinone9/10, were significantly higher in the CNS, but not in plasma, of SOD1G93A mice, suggesting that CoQ redox system might participate in the mechanisms trying to counteract the pathology progression. Therefore, the very low increases of CoQ10 induced by oral treatments in CNS might be not sufficient to provide significant neuroprotection in SOD1G93A mice.

Investigating cell death mechanisms in amyotrophic lateral sclerosis using transcriptomics

Amyotrophic lateral sclerosis (ALS) is a motor neuron disease characterized by degeneration and loss of upper and lower motor neurons from the motor cortex, brainstem and spinal cord although evidence is suggesting that there is further involvement of other cell types in the surrounding tissue. Transcriptomic analysis by gene expression profiling using microarray technology has enabled the determination of patterns of cell death in the degenerating tissues. This work has examined gene expression at the level of the tissue and individual cell types in both sporadic and familial forms of the disease. In addition, further studies have examined the differential vulnerability of neuronal cells in different regions of the central nervous system. Model systems have also provided further information to help unravel the mechanisms that lead to death of the motor neurons in disease and also provided novel insights. In this review we shall describe the methods that have been used in these investigations and describe how they have contributed to our knowledge of the cell death mechanisms in ALS.

Ribonuclease 4 protects neuron degeneration by promoting angiogenesis, neurogenesis, and neuronal survival under stress

Altered RNA processing is an underlying mechanism of amyotrophic lateral sclerosis (ALS). Missense mutations in a number of genes involved in RNA function and metabolisms are associated with ALS. Among these genes is angiogenin (ANG), the fifth member of the vertebrate-specific, secreted ribonuclease superfamily. ANG is an angiogenic ribonuclease, and both its angiogenic and ribonucleolytic activities are important for motor neuron health. Ribonuclease 4 (RNASE4), the fourth member of this superfamily, shares the same promoters with ANG and is co-expressed with ANG. However, the biological role of RNASE4 is unknown. To determine whether RNASE4 is involved in ALS pathogenesis, we sequenced the coding region of RNASE4 in ALS and control subjects and characterized the angiogenic, neurogenic, and neuroprotective activities of RNASE4 protein. We identified an allelic association of SNP rs3748338 with ALS and demonstrated that RNASE4 protein is able to induce angiogenesis in in vitro, ex vivo, and in vivo assays. RNASE4 also induces neural differentiation of P19 mouse embryonal carcinoma cells and mouse embryonic stem cells. Moreover, RNASE4 not only stimulates the formation of neurofilaments from mouse embryonic cortical neurons, but also protects hypothermia-induced degeneration. Importantly, systemic treatment with RNASE4 protein slowed weight loss and enhanced neuromuscular function of SOD1 (G93A) mice.

Concurrence of multiple sclerosis and amyotrophic lateral sclerosis in patients with hexanucleotide repeat expansions of C9ORF72

BackgroundCrossover in the pathogenic mechanisms of amyotrophic lateral sclerosis (ALS) and multiple sclerosis (MS) has been described but is poorly understood. A GGGGCC hexanucleotide repeat expansion of C9ORF72 has recently...

Amyotrophic Lateral Sclerosis: New Insights into Underlying Molecular Mechanisms and Opportunities for Therapeutic Intervention

Recent years have witnessed a renewed interest in the pathogenic mechanisms of amyotrophic lateral sclerosis (ALS), a late-onset progressive degeneration of motor neurons. The discovery of new genes associated with the familial form of the disease, along with a deeper insight into pathways already described for this disease, has led scientists to reconsider previous postulates. While protein misfolding, mitochondrial dysfunction, oxidative damage, defective axonal transport, and excitotoxicity have not been dismissed, they need to be re-examined as contributors to the onset or progression of ALS in the light of the current knowledge that the mutations of proteins involved in RNA processing, apparently unrelated to the previous "old partners," are causative of the same phenotype. Thus, newly envisaged models and tools may offer unforeseen clues on the etiology of this disease and hopefully provide the key to treatment.

Molecular Mechanisms in Amyotrophic Lateral Sclerosis: The Role of Angiogenin, a Secreted RNase

Amyotrophic lateral sclerosis is a fatal neurodegenerative disease caused by the loss of motoneurons. The precise molecular and cellular basis for neuronal death is not yet well established, but the contemporary view is that it is a culmination of multiple aberrant biological processes. Among the proposed mechanisms of motoneuron degeneration, alterations in the homeostasis of RNA binding proteins (RBP) and the consequent changes in RNA metabolism have received attention recently. The ribonuclease, angiogenin was one of the first RBPs associated with familial and sporadic ALS. It is enriched in motoneurons under physiological conditions, and is required for motoneuron survival under stress conditions. Furthermore, delivery of angiogenin protects cultured motoneurons against stress-induced injury, and significantly increases the survival of motoneurons in SODG93A mice. In this overview on the role of angiogenin in RNA metabolism and in the control of motoneuron survival, we discuss potential pathogenic mechanisms of angiogenin dysfunction relevant to ALS and other neurodegenerative disorders. We also discuss recent evidence demonstrating that angiogenin secreted from stressed motoneurons may alter RNA metabolism in astrocytes.

Inhibitory Synaptic Regulation of Motoneurons: A New Target of Disease Mechanisms in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is the third most common adult-onset neurodegenerative disease. It causes the degeneration of motoneurons and is fatal due to paralysis, particularly of respiratory muscles. ALS can be inherited, and specific disease-causing genes have been identified, but the mechanisms causing motoneuron death in ALS are not understood. No effective treatments exist for ALS. One well-studied theory of ALS pathogenesis involves faulty RNA editing and abnormal activation of specific glutamate receptors as well as failure of glutamate transport resulting in glutamate excitotoxicity; however, the excitotoxicity theory is challenged by the inability of anti-glutamate drugs to have major disease-modifying effects clinically. Nevertheless, hyperexcitability of upper and lower motoneurons is a feature of human ALS and transgenic (tg) mouse models of ALS. Motoneuron excitability is strongly modulated by synaptic inhibition mediated by presynaptic glycinergic and GABAergic innervations and postsynaptic glycine receptors (GlyR) and GABA(A) receptors; yet, the integrity of inhibitory systems regulating motoneurons has been understudied in experimental models, despite findings in human ALS suggesting that they may be affected. We have found in tg mice expressing a mutant form of human superoxide dismutase-1 (hSOD1) with a Gly93 → Ala substitution (G93A-hSOD1), causing familial ALS, that subsets of spinal interneurons degenerate. Inhibitory glycinergic innervation of spinal motoneurons becomes deficient before motoneuron degeneration is evident in G93A-hSOD1 mice. Motoneurons in these ALS mice also have insufficient synaptic inhibition as reflected by smaller GlyR currents, smaller GlyR clusters on their plasma membrane, and lower expression of GlyR1α mRNA compared to wild-type motoneurons. In contrast, GABAergic innervation of ALS mouse motoneurons and GABA(A) receptor function appear normal. Abnormal synaptic inhibition resulting from dysfunction of interneurons and motoneuron GlyRs is a new direction for unveiling mechanisms of ALS pathogenesis that could be relevant to new therapies for ALS.

Biomarkers in amyotrophic lateral sclerosis: opportunities and limitations

Insights into the mechanisms of amyotrophic lateral sclerosis (ALS) have relied predominantly on the study of postmortem tissue. Modern technology has improved the ability of scientists to probe effectively the underlying biology of ALS by examination of genomic, proteomic and physiological changes in patients, as well as to monitor functional and structural changes in patients over the course of disease. While effective treatments for ALS are lacking, the discovery of biomarkers for this disease offers clinicians tools for rapid diagnosis, improved ways to monitor disease progression, and insights into the pathophysiology of sporadic ALS. The ultimate aim is to broaden the therapeutic options for patients with this disease.

Alterations of T cell subsets in ALS: a systemic immune activation?

There is evidence that immunological factors may involved in pathogenetic mechanisms of amyotrophic lateral sclerosis (ALS). Few studies to date have explored the status of the systemic immune response in patients with ALS. In order to examine whether systemic immune activation is observed in patients with ALS, we measured the number of T cell subsets by flow cytometry in 36 patients with ALS and 35 normal controls. CD8 cytotoxic T cells and natural killer (NK) T cells were significantly increased in our patients with ALS compared with the control group (P = 0.02 and P = 0.04, respectively). Treg cells were significantly reduced compared with normal controls (P = 0.01). Treg cells were also negatively correlated with progression of the disease (P = 0.017). Our results suggest a systemic immune activation in patients with ALS. The high production of CD8(+) T and NKT cells may suggest an immunological reaction to some unknown or undetected endogenous proteins or viruses. A probably dual (neurodestructive or neuroprotective) inflammatory function of Treg cells cannot be excluded.

Ghrelin protects spinal cord motoneurons against chronic glutamate-induced excitotoxicity via ERK1/2 and phosphatidylinositol-3-kinase/Akt/glycogen synthase kinase-3β pathways

Excitotoxic degeneration of spinal cord motoneurons has been proposed as a pathogenic mechanism in amyotrophic lateral sclerosis (ALS). Recently, we have reported that ghrelin, an endogenous ligand for growth hormone secretagogue receptor (GHS-R) 1a, functions as a neuroprotective factor in various animal models of neurodegenerative diseases. In this study, the potential neuroprotective effects of ghrelin against chronic glutamate-induced cell death were studied by exposing organotypic spinal cord cultures (OSCC) to threohydroxyaspartate (THA), as a model of excitotoxic motoneuron degeneration. Ghrelin receptor was expressed on spinal cord motoneurons. Exposure of OSCC to THA for 3weeks resulted in a significant loss of motoneurons. However, THA-induced loss of motoneurons was significantly reduced by treatment of ghrelin. Exposure of OSCC to the receptor-specific antagonist D-Lys-3-GHRP-6 abolished the protective effect of ghrelin against THA. Treatment of spinal cord cultures with ghrelin caused rapid phosphorylation of extracellular signal-regulated kinase 1/2, Akt, and glycogen synthase kinase-3β (GSK-3β). The effect of ghrelin on motoneuron survival was blocked by the MEK inhibitor PD98059 and the phosphatidylinositol-3-kinase (PI3K) inhibitor LY294002. Taken together, these findings indicate that ghrelin has neuroprotective effects against chronic glutamate toxicity by activating the MAPK and PI3K/Akt signaling pathways and suggest that administration of ghrelin may have the potential therapeutic value for the prevention of motoneuron degeneration in human ALS. Our data also suggest that PI3K/Akt-mediated inactivation of GSK-3β in motoneurons contributes to the protective effect of ghrelin.

Abstract #5: A Phase I, Dosage-Escalation Study of Creatine Monohydrate in Subjects with Amyotrophic Lateral Sclerosis

Background Mitochondrial dysfunction is a proposed pathologic mechanism in amyotrophic lateral sclerosis (ALS). Creatine has been shown to stabilize the mitochondrial transition pore, buffer intracellular energy stores, stimulate synaptic glutamate uptake, and scavenge reactive oxygen species. It is suggested that creatine is neuroprotective in vivo and that this effect is dose-dependant. Creatine is safe and well-tolerated but failed to demonstrate efficacy in ALS at 5 and 10 g/day. Experience with creatine in HD patients suggests that creatine may be neuroprotective at higher dosages. The purpose of this study is to establish steady-state serum pharmacokinetics (PK) of creatine at several dosages, and to evaluate the effects of creatine on brain metabolites using proton magnetic resonance spectroscopy ( 1 H-MRS) Methods Six participants with ALS received creatine at three weekly escalating oral dosages (5, 10, and 15 g BID). Creatine blood levels were collected over 5 hours at each visit. MRS was performed at baseline and 5 days after each dose increase. Pharmacokinetic parameters were estimated by measuring the area under the curve (AUC) for each dosage group. Changes in brain metabolite levels on MRS were compared within subjects before and after treatments using repeated measures RM-ANOVA. Results To Date Mean pre-dose steady-state creatine plasma concentrations were 20.3, 39.3, and 61.5 μg/mL at 5, 10, 15 g BID, respectively. Creatine spectra increased by 8% ( p = 0.06) and glutamate + glutamine spectra decreased by 17% ( p = 0.039) at higher dosages. There were no safety concerns at any of the dosages. Discussion/Conclusion Creatine plasma concentrations increased in a dose-dependant manner. Creatine appears to cross the blood–brain barrier, and oral administration of 15 g BID is associated with increased in vivo brain creatine concentrations and decreased glutamate concentrations. The decrease in brain glutamate concentration with increased creatine dosages is of particular interest given the role of glutamate-mediated injury to motor neurons in ALS. The results of this study support that 15 g BID creatine could be tested as a therapeutic dosage in ALS clinical trials. These data also support MRS as a potential biomarker for creatine effect on brain metabolites.

Superoxide Dismutase 1 and tgSOD1G93A Mouse Spinal Cord Seed Fibrils, Suggesting a Propagative Cell Death Mechanism in Amyotrophic Lateral Sclerosis

BackgroundAmyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that specifically affects motor neurons and leads to a progressive and ultimately fatal loss of function, resulting in death typically within 3 to 5 years of diagnosis. The disease starts with a focal centre of weakness, such as one limb, and appears to spread to other parts of the body. Mutations in superoxide dismutase 1 (SOD1) are known to cause disease and it is generally accepted they lead to pathology not by loss of enzymatic activity but by gain of some unknown toxic function(s). Although different mutations lead to varying tendencies of SOD1 to aggregate, we suggest abnormal proteins share a common misfolding pathway that leads to the formation of amyloid fibrils.Methodology/Principal FindingsHere we demonstrate that misfolding of superoxide dismutase 1 leads to the formation of amyloid fibrils associated with seeding activity, which can accelerate the formation of new fibrils in an autocatalytic cascade. The time limiting event is nucleation to form a stable protein “seed” before a rapid linear polymerisation results in amyloid fibrils analogous to other protein misfolding disorders. This phenomenon was not confined to fibrils of recombinant protein as here we show, for the first time, that spinal cord homogenates obtained from a transgenic mouse model that overexpresses mutant human superoxide dismutase 1 (the TgSOD1G93A mouse) also contain amyloid seeds that accelerate the formation of new fibrils in both wildtype and mutant SOD1 protein in vitro.Conclusions/SignificanceThese findings provide new insights into ALS disease mechanism and in particular a mechanism that could account for the spread of pathology throughout the nervous system. This model of disease spread, which has analogies to other protein misfolding disorders such as prion disease, also suggests it may be possible to design assays for therapeutics that can inhibit fibril propagation and hence, possibly, disease progression.

Cannabis and Amyotrophic Lateral Sclerosis: Hypothetical and Practical Applications, and a Call for Clinical Trials

Significant advances have increased our understanding of the molecular mechanisms of amyotrophic lateral sclerosis (ALS), yet this has not translated into any greatly effective therapies. It appears that a number of abnormal physiological processes occur simultaneously in this devastating disease. Ideally, a multidrug regimen, including glutamate antagonists, antioxidants, a centrally acting anti-inflammatory agent, microglial cell modulators (including tumor necrosis factor alpha [TNF-alpha] inhibitors), an antiapoptotic agent, 1 or more neurotrophic growth factors, and a mitochondrial function-enhancing agent would be required to comprehensively address the known pathophysiology of ALS. Remarkably, cannabis appears to have activity in all of those areas. Preclinical data indicate that cannabis has powerful antioxidative, anti-inflammatory, and neuroprotective effects. In the G93A-SOD1 ALS mouse, this has translated to prolonged neuronal cell survival, delayed onset, and slower progression of the disease. Cannabis also has properties applicable to symptom management of ALS, including analgesia, muscle relaxation, bronchodilation, saliva reduction, appetite stimulation, and sleep induction. With respect to the treatment of ALS, from both a disease modifying and symptom management viewpoint, clinical trials with cannabis are the next logical step. Based on the currently available scientific data, it is reasonable to think that cannabis might significantly slow the progression of ALS, potentially extending life expectancy and substantially reducing the overall burden of the disease.

A possible haemodynamic mechanism for Amyotrophic Lateral Sclerosis

The hypothesis proposed in this article is that a haemodynamic mechanism may cause amyotrophic lateral sclerosis (ALS). The hypothesis is synthesized from three separate streams of medical research: (1) multiple sclerosis (MS) research; (2) ALS research; (3) atherosclerosis research. Each research stream was reviewed as prerequisite for proposing the hypothesis. A vascular mechanism for MS was first advanced in the medical literature 130years ago. Seventy years ago researchers knew that the plaques aligned along a central vein, and the wall of that central vein was damaged and leaky. Twenty-five years ago the refluxing blood mechanism was proposed. Zamboni imaged the veins of MS patients in 2007 and saw stenoses, twistings, and membrane blockages in the jugular, azygous, and vertebral veins, and refluxing venous blood upstream of the constrictions. The refluxing blood damages the blood-brain-barrier (BBB) of the veins. Leakage of blood components into the central nervous system then causes the plaques in the brains of MS people. Zamboni dilated the venous constrictions endovascularly, and the MS symptoms and brain plaques diminished dramatically. ALS research has recently revealed that this disease is started by blood-spinal cord-barrier (BSCB) damage. The ALS mutant mouse shows BSCB damage and down regulation of tight junction proteins Occludin and ZO-1 before motor neuron harm. Samplings of ALS patients' spinal cords show downregulation of mRNA for tight junction proteins compared to controls. Atherosclerosis research provides the mechanism for how the refluxing blood breaks the tight junctions between the endothelial cells of the veins. Atherosclerosis research on blood flow effects shows that normal pulsatile laminar blood flow is necessary for maintenance of the tight junctions between endothelial cells. Abnormal flow conditions, such as turbulent, stopped, or reversed flow, cause downregulation of tight junction proteins Occludin and ZO-1. Blood flow (haemodynamic) effects explain the BBB damage in MS and may explain the BSCB damage in ALS. The hypothesis: ALS is caused by constrictions in veins draining the spinal cord and brain, which cause venous reflux, which downregulates tight junction proteins Occludin and ZO-1, which leads to breaks in the tight junctions between endothelial cells in the veins, which leads to leakage of toxic blood components into CNS tissue. The consequences of the hypothesis are discussed. If a venous constriction can be reached endovascularly it can be dilated, and such dilation may constitute cure of ALS.

Interleukin-15 and Interleukin-12 Are Elevated in Serum and Cerebrospinal Fluid of Patients with Amyotrophic Lateral Sclerosis

Background: There is evidence that immunological factors may be involved in pathogenic mechanisms of amyotrophic lateral sclerosis (ALS). Interleukin (IL)-15 and IL-12 are proinflammatory cytokines produced by activated blood and glial cells. They promote T cell differentiation and proliferation. Patients and Methods: We measured by ELISA serum and cerebrospinal fluid (CSF) levels of IL-15 and IL-12 in 21 patients with ALS and 19 patients with other noninflammatory neurological disorders (NIND) studied as a control group. IL-15 and IL-12 serum and CSF levels were also correlated with duration of the disease, the disability level determined using the revised ALS Functional Rating Scale and the clinical subtype of the disease onset in patients with ALS. Results: IL-15 and IL-12 serum levels were higher in patients with ALS as compared with patients with NIND (p = 0.014 and p = 0.011, respectively). IL-15 and IL-12 CSF levels were also increased in patients with ALS (p = 0.011 and p = 0.005, respectively). IL-15 and IL-12 levels were not correlated with disease duration, disability scale or clinical subtype of the disease onset in ALS patients. Conclusions: Our findings suggest that these molecules may be involved in the pathogenic mechanisms acting as potential markers of immune activation in ALS.

Interleukin-17 and interleukin-23 are elevated in serum and cerebrospinal fluid of patients with ALS: a reflection of Th17 cells activation?

There is evidence that immunological factors may involved in pathogenetic mechanisms of amyotrophic lateral sclerosis (ALS). Th17 cells are characterized by predominant production of IL-17 and are suggested to be crucial in destructive autoimmunity. Interleukin-23 (IL-23) appears to play a supporting role in the continued stimulation and survival of Th17. We measured by enzyme-like immunosorbent assay (ELISA) serum and cerebrospinal fluid (CSF) levels of IL-17 and IL-23 in 22 patients with ALS and 19 patients with other non-inflammatory neurological disorders (NIND) studied as a control group. IL-17 and IL-23 serum and CSF levels were also correlated with duration of the disease, the disability level and the clinical subtype of the disease onset in patients with ALS. IL-17 and IL-23 serum levels were higher in patients with ALS as compared with patients with NIND (P = 0.015 and P = 0.002 respectively). IL-17 and IL-23 CSF levels were also increased in patients with ALS (P = 0.0006 and P = 0.000001 respectively). IL-17 and IL-23 levels were not correlated with disease duration, disability scale or clinical subtype of the disease onset in ALS patients. Our findings suggest that these molecules may be involved in the pathogenetic mechanisms acting as potential markers of Th17 cells activation in ALS.

Nuclear Erythroid 2-Related Factor 2-Antioxidative Response Element Signaling Pathway in Motor Cortex and Spinal Cord in Amyotrophic Lateral Sclerosis

Oxidative stress and inflammation are important pathogenetic mechanisms in amyotrophic lateral sclerosis (ALS). Nuclear erythroid 2-related factor 2 (Nrf2) is a basic region leucine-zipper transcription factor that binds to the antioxidant response element, thereby regulating the expression of many genes that are involved in cellular antioxidant and anti-inflammatory defense. Under normal conditions, Nrf2 activation is inhibited by Kelch-like ECH-associated protein 1 (Keap1). We investigated the potential involvement of the Nrf2/antioxidant response element signaling pathway in the selective degeneration of motor neurons in ALS. Nrf2 and Keap1 expression was analyzed in primary motor cortex and spinal cord postmortem tissue samples from ALS patients and controls by in situ hybridization histochemistry, quantitative real-time polymerase chain reaction, immunohistochemistry, and Western blot analysis. In ALS samples, there was a reduction of Nrf2 mRNA and protein expression in neurons, whereas Keap1 mRNA expression was increased in the motor cortex. These results suggest that alterations in this signaling cascade occur in motor neurons in ALS and that they may contribute to chronic motor neuron degeneration.

Gender difference in levels of Cu/Zn superoxide dismutase (SOD1) in cerebrospinal fluid of patients with amyotrophic lateral sclerosis

Currently the best studied mechanism for amyotrophic lateral sclerosis (ALS) is the one caused by mutations in the gene for cytosolic Cu/Zn-binding superoxide dismutase (SOD1). Mutant SOD1 protein causes motor neuron degeneration due to the gain of a novel toxic function. To evaluate the relevance of SOD1 levels in cerebrospinal fluid (CSF) in ALS patients, the SOD1 concentration was immunoassayed in the CSF of 11 patients with ALS and 19 neurological controls. The mean level of SOD1 in CSF from all samples was 45.5+/-11.3 ng/ml. There was no statistically significant difference between the levels of SOD1 in CSF of ALS patients and neurological control subjects. Here we show that the SOD1 concentration in the CSF is significantly higher in male ALS patients (54.0+/-9.0 ng/ml) compared to female ALS patients (38.1+/-6.4 ng/ml) (p=0.007). This gender difference is not observed in the CSF of neurological controls. This is the first report of a potential gender difference in levels of SOD1 in CSF of ALS patients. Further investigation of larger sample groups is needed to determine whether it is relevant to gender related differences in disease incidence.

Amyotrophic Lateral Sclerosis-associated Copper/Zinc Superoxide Dismutase Mutations Preferentially Reduce the Repulsive Charge of the Proteins

We provide bioinformatical evidence that protein charge plays a key role in the disease mechanism of amyotrophic lateral sclerosis (ALS). Analysis of 100 ALS-associated mutations in copper/zinc superoxide dismutase (SOD1) shows that these are site-selective with a preference to decrease the proteins' net repulsive charge. For each SOD1 monomer this charge is normally -6. Because biomolecules as a rule maintain net negative charge to assure solubility in the cellular interior, the result lends support to the hypothesis of protein aggregation as an initiating event in the ALS pathogenesis. The strength of the preferential reduction of repulsive charge is higher in SOD1-associated ALS than in other inherited protein disorders.

ALS: life and death in a bad neighborhood

The role of inflammatory mechanisms in amyotrophic lateral sclerosis is a hotly debated topic. Findings in a mouse model now add weight to arguments that targeting of inflammatory cells might be a fruitful therapeutic approach.