Recent advances in motor neuron disease

Revolutionising Neurological Therapeutics: Investigating Drug Repurposing Strategies

Repurposing drugs (DR) has become a viable approach to hasten the search for cures for neurodegenerative diseases (NDs). This review examines different off-target and on-target drug discovery techniques and how they might be used to find possible treatments for non-diagnostic depressions. Off-target strategies look at the known or unknown side effects of currently approved drugs for repositioning, whereas on-target strategies connect disease pathways to targets that can be treated with drugs. The review highlights the potential of experimental and computational methodologies, such as machine learning, proteomic techniques, network and genomics-based approaches, and in silico screening, in uncovering new drug-disease correlations. It also looks at difficulties and failed attempts at drug repurposing for NDs, highlighting the necessity of exact and standardised procedures to increase success rates. This review's objectives are to address the purpose of drug repurposing in human disorders, particularly neurological diseases, and to provide an overview of repurposing candidates that are presently undergoing clinical trials for neurological conditions, along with any possible causes and early findings. We then include a list of drug repurposing strategies, restrictions, and difficulties for upcoming research.

Synaptopathy: presynaptic convergence in frontotemporal dementia and amyotrophic lateral sclerosis

Frontotemporal dementia and amyotrophic lateral sclerosis are common forms of neurodegenerative disease that share overlapping genetics and pathologies. Crucially, no significantly disease-modifying treatments are available for either disease. Identifying the earliest changes that initiate neuronal dysfunction is important for designing effective intervention therapeutics. The genes mutated in genetic forms of frontotemporal dementia and amyotrophic lateral sclerosis have diverse cellular functions, and multiple disease mechanisms have been proposed for both. Identification of a convergent disease mechanism in frontotemporal dementia and amyotrophic lateral sclerosis would focus research for a targetable pathway, which could potentially effectively treat all forms of frontotemporal dementia and amyotrophic lateral sclerosis (both familial and sporadic). Synaptopathies are diseases resulting from physiological dysfunction of synapses, and define the earliest stages in multiple neuronal diseases, with synapse loss a key feature in dementia. At the presynapse, the process of synaptic vesicle recruitment, fusion and recycling is necessary for activity-dependent neurotransmitter release. The unique distal location of the presynaptic terminal means the tight spatio-temporal control of presynaptic homeostasis is dependent on efficient local protein translation and degradation. Recently, numerous publications have shown that mutations associated with frontotemporal dementia and amyotrophic lateral sclerosis present with synaptopathy characterized by presynaptic dysfunction. This review will describe the complex local signalling and membrane trafficking events that occur at the presynapse to facilitate neurotransmission and will summarize recent publications linking frontotemporal dementia/amyotrophic lateral sclerosis genetic mutations to presynaptic function. This evidence indicates that presynaptic synaptopathy is an early and convergent event in frontotemporal dementia and amyotrophic lateral sclerosis and illustrates the need for further research in this area, to identify potential therapeutic targets with the ability to impact this convergent pathomechanism.

Cholesterol dyshomeostasis in amyotrophic lateral sclerosis: cause, consequence, or epiphenomenon?

Amyotrophic lateral sclerosis (ALS), the most common adult-onset motor neuron disease, is characterized by the selective degeneration of motor neurons leading to paralysis and eventual death. Multiple pathogenic mechanisms, including systemic dysmetabolism, have been proposed to contribute to ALS. Among them, dyslipidemia, i.e., abnormal level of cholesterol and other lipids in the circulation and central nervous system (CNS), has been reported in ALS patients, but without a consensus. Cholesterol is a constituent of cellular membranes and a precursor of steroid hormones, oxysterols, and bile acids. Consequently, optimal cholesterol levels are essential for health. Due to the blood-brain barrier (BBB), cholesterol cannot move between the CNS and the rest of the body. As such, cholesterol metabolism in the CNS is proposed to operate autonomously. Despite its importance, it remains elusive how cholesterol dyshomeostasis may contribute to ALS. In this review, we aim to describe the current state of cholesterol metabolism research in ALS, identify unresolved issues, and provide potential directions.

Reproductive History and Age of Onset for Women Diagnosed with Amyotrophic Lateral Sclerosis: Data from the National ALS Registry: 2010-2018

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a neurological disease of largely unknown etiology with no cure. The National ALS Registry is a voluntary online system that collects demographic and reproductive history (females only) data from patients with ALS. We will examine the association between demographic and reproductive history among female patients aged >18 years and various ages of onset for ALS.

METHODS

Data from a cross-sectional study were collected and examined for 1,018 female ALS patients. Patient characteristics examined were demographics including race, BMI, and familial history of ALS. Among patients, information on reproductive history, including age at menopause, ever pregnant, and age at first pregnancy was collected. Unadjusted and adjusted logistic regression models were used to estimate OR and 95% CI in this study.

RESULTS

Women were more likely to be diagnosed with ALS before age 60 if they were nonwhite (p = 0.015), had attended college (p = 0.0012), had a normal BMI at age 40 (p < 0.0001), completed menopause before age 50 (p < 0.0001), and had never been pregnant (p = 0.046) in the univariate analysis. Women diagnosed with ALS before age 60 were also more likely to have limb site of onset (p < 0.0001). In the multivariate analysis, those who completed menopause before age 50 were more likely to be diagnosed with ALS before age 60 (OR = 1.8, 95% CI: 1.4-2.3) compared with women who completed menopause at or after age 50, after controlling for race, ever pregnant, age at first pregnancy, family history of ALS, education status, smoking history, and BMI at age 40. For women who were diagnosed with ALS before age 50, the odds of them entering menopause before age 50 climb to 48.7 (95% CI: 11.8, 200.9). The mean age of ALS diagnosis for women who completed menopause before age 50 was 58 years and 64 years for women who entered menopause after age 50 (p < 0.0001).

CONCLUSION

Women who reported completing menopause before age 50 were significantly more likely to be diagnosed with ALS before age 60 compared with those who reported entering menopause after age 50. More research is needed to determine the relationship between female reproductive history, especially regarding endogenous estrogen exposure and early-onset ALS.

Altered Mitochondrial Dynamics in Motor Neuron Disease: An Emerging Perspective

Mitochondria plays privotal role in diverse pathways that regulate cellular function and survival, and have emerged as a prime focus in aging and age-associated motor neuron diseases (MNDs), such as amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Accumulating evidence suggests that many amyloidogenic proteins, including MND-associated RNA/DNA-binding proteins fused in sarcoma (FUS) and TAR DNA binding protein (TDP)-43, are strongly linked to mitochondrial dysfunction. Animal model and patient studies have highlighted changes in mitochondrial structure, plasticity, replication/copy number, mitochondrial DNA instability, and altered membrane potential in several subsets of MNDs, and these observations are consistent with the evidence of increased excitotoxicity, induction of reactive oxygen species, and activation of intrinsic apoptotic pathways. Studies in MND rodent models also indicate that mitochondrial abnormalities begin prior to the clinical and pathological onset of the disease, suggesting a causal role of mitochondrial dysfunction. Our recent studies, which demonstrated the involvement of specific defects in DNA break-ligation mediated by DNA ligase 3 (LIG3) in FUS-associated ALS, raised a key question of its potential implication in mitochondrial DNA transactions because LIG3 is essential for both mitochondrial DNA replication and repair. This question, as well as how wild-type and mutant MND-associated factors affect mitochondria, remain to be elucidated. These new investigation avenues into the mechanistic role of mitochondrial dysfunction in MNDs are critical to identify therapeutic targets to alleviate mitochondrial toxicity and its consequences. In this article, we critically review recent advances in our understanding of mitochondrial dysfunction in diverse subgroups of MNDs and discuss challenges and future directions.

The Genetic Diagnosis of Neurodegenerative Diseases and Therapeutic Perspectives

Genetics has led to a new focus regarding approaches to the most prevalent diseases today. Ascertaining the molecular secrets of neurodegenerative diseases will lead to developing drugs that will change natural history, thereby affecting the quality of life and mortality of patients. The sequencing of candidate genes in patients suffering neurodegenerative pathologies is faster, more accurate, and has a lower cost, thereby enabling algorithms to be proposed regarding the risk of neurodegeneration onset in healthy persons including the year of onset and neurodegeneration severity. Next generation sequencing has resulted in an explosion of articles regarding the diagnosis of neurodegenerative diseases involving exome sequencing or sequencing a whole gene for correlating phenotypical expression with genetic mutations in proteins having key functions. Many of them occur in neuronal glia, which can trigger a proinflammatory effect leading to defective proteins causing sporadic or familial mutations. This article reviews the genetic diagnosis techniques and the importance of bioinformatics in interpreting results from neurodegenerative diseases. Risk scores must be established in the near future regarding diseases with a high incidence in healthy people for defining prevention strategies or an early start for giving drugs in the absence of symptoms.

Yeast genetic interaction screen of human genes associated with amyotrophic lateral sclerosis: identification of MAP2K5 kinase as a potential drug target

To understand disease mechanisms, a large-scale analysis of human–yeast genetic interactions was performed. Of 1305 human disease genes assayed, 20 genes exhibited strong toxicity in yeast. Human–yeast genetic interactions were identified by en masse transformation of the human disease genes into a pool of 4653 homozygous diploid yeast deletion mutants with unique barcode sequences, followed by multiplexed barcode sequencing to identify yeast toxicity modifiers. Subsequent network analyses focusing on amyotrophic lateral sclerosis (ALS)-associated genes, such as optineurin (OPTN) and angiogenin (ANG), showed that the human orthologs of the yeast toxicity modifiers of these ALS genes are enriched for several biological processes, such as cell death, lipid metabolism, and molecular transport. When yeast genetic interaction partners held in common between human OPTN and ANG were validated in mammalian cells and zebrafish, MAP2K5 kinase emerged as a potential drug target for ALS therapy. The toxicity modifiers identified in this study may deepen our understanding of the pathogenic mechanisms of ALS and other devastating diseases.

The Neurotoxic TAU45-230 Fragment Accumulates in Upper and Lower Motor Neurons in Amyotrophic Lateral Sclerosis Subjects

Amyotrophic lateral sclerosis (ALS) is a progressive and lethal neurodegenerative disease characterized by the loss of upper and lower motor neurons leading to muscle paralysis in affected individuals. Numerous mechanisms have been implicated in the death of these neurons. However, the pathobiology of this disease has not been completely elucidated. In the present study, we investigated to what extent tau cleavage and the generation of the neurotoxic tau45-230 fragment is associated with ALS. Quantitative Western blot analysis indicated that high levels of tau45-230 accumulated in lumbar and cervical spinal cord specimens obtained from ALS subjects. This neurotoxic tau fragment was also detected in ALS upper motor neurons located in the precentral gyrus. Our results also showed that tau45-230 aggregates were present in the spinal cord of ALS patients. On the other hand, this neurotoxic fragment was not generated in a mouse model of a familial form of this disease. Together, these results suggest a potential role for this neurotoxic tau fragment in the mechanisms leading to the degeneration of motor neurons in the context of sporadic ALS.

Recent progress towards an effective treatment of amyotrophic lateral sclerosis using the SOD1 mouse model in a preclinical setting

Amyotrophic lateral sclerosis (ALS) is a progressive, fatal and incurable neurodegenerative disorder. Motor neurone degeneration can be caused by genetic mutation but the exact etiology of the disease, particularly for sporadic illness, still remains unclear. Therapeutics which target known pathogenic mechanisms involved in ALS, such as protein aggregation, oxidative stress, apoptosis, inflammation, endoplasmic reticulum stress and mitochondria dysfunction, are currently being pursued in order to provide neuroprotection which may be able to slow down, or perhaps even halt, disease progression. This present review focuses on the compounds which have been recently evaluated using the SOD1 mouse model, the most widely used preclinical model for ALS research.

Imaging of brain TSPO expression in a mouse model of amyotrophic lateral sclerosis with (18)F-DPA-714 and micro-PET/CT

PURPOSE

To evaluate the feasibility and sensitivity of (18)F-DPA-714 for the study of microglial activation in the brain and spinal cord of transgenic SOD1(G93A) mice using high-resolution PET/CT and to evaluate the Iba1 and TSPO expression with immunohistochemistry.

METHODS

Nine symptomatic SOD1(G93A) mice (aged 117 ± 12.7 days, clinical score range 1 - 4) and five WT SOD1 control mice (aged 108 ± 28.5 days) underwent (18)F-DPA-714 PET/CT. SUV ratios were calculated by normalizing the cerebellar (rCRB), brainstem (rBS), motor cortex (rMCX) and cervical spinal cord (rCSC) activities to that of the frontal association cortex. Two WT SOD1 and six symptomatic SOD1(G93A) mice were studied by immunohistochemistry.

RESULTS

In the symptomatic SOD1(G93A) mice, rCRB, rBS and rCSC were increased as compared to the values in WT SOD1 mice, with a statistically significantly difference in rBS (2.340 ± 0.784 vs 1.576 ± 0.287, p = 0.014). Immunofluorescence studies showed that TSPO expression was increased in the trigeminal, facial, ambiguus and hypoglossal nuclei, as well as in the spinal cord, of symptomatic SOD1(G93A) mice and was colocalized with increased Iba1 staining.

CONCLUSION

Increased (18)F-DPA-714 uptake can be detected with high-resolution PET/CT in the brainstem of transgenic SOD1(G93A) mice, a region known to be a site of degeneration and increased microglial activation in amyotrophic lateral sclerosis, in agreement with increased TSPO expression in the brainstem nuclei shown by immunostaining. Therefore, (18)F-DPA-714 PET/CT might be a suitable tool to evaluate microglial activation in the SOD1(G93A) mouse model.

Frontotemporal dementia: a bridge between dementia and neuromuscular disease

The concept that frontotemporal dementia (FTD) is a purely cortical dementia has largely been refuted by the recognition of its close association with motor neuron disease, and the identification of transactive response DNA-binding protein 43 (TDP-43) as a major pathological substrate underlying both diseases. Genetic findings have transformed this field and revealed connections between disorders that were previous thought clinically unrelated. The discovery that the C9ORF72 locus is responsible for the majority of hereditary FTD, amyotrophic lateral sclerosis (ALS), and FTD-ALS cases and the understanding that repeat-containing RNA plays a crucial role in pathogenesis of both disorders has paved the way for the development of potential biomarkers and therapeutic targets for these devastating diseases. In this review, we summarize the historical aspects leading up to our current understanding of the genetic, clinical, and neuropathological overlap between FTD and ALS, and include brief discussions on chronic traumatic encephalopathy (CTE), given its association with TDP-43 pathology, its associated increased dementia risk, and reports of ALS in CTE patients. In addition, we describe other genetic associations between dementia and neuromuscular disease, such as inclusion body myositis with Paget's disease and FTD.

Developments in treatments for amyotrophic lateral sclerosis via intracerebroventricular or intrathecal delivery

INTRODUCTION

Amyotrophic lateral scleroses (ALS) are neurodegenerative disorders primarily affecting the motor system. These incurable disorders are relentlessly progressive and typically limit survival to 2 - 5 years after disease onset. An improved knowledge about disease-causing genes, disease proteins and pathways has revealed considerable heterogeneity in ALS. Novel targeted therapies are being developed, but getting these beyond the BBB remains a challenge.

AREAS COVERED

The authors review the intracerebroventricular and intrathecal delivery of drugs for the treatment of ALS in preclinical and clinical studies.

EXPERT OPINION

Lack of BBB permeability should not hold back the development of promising treatments for ALS, as the available evidence suggest that direct intrathecal or intracerebroventricular administration of drug is a feasible delivery route in patients with ALS.

Zebrafish models of human motor neuron diseases: advantages and limitations

Motor neuron diseases (MNDs) are an etiologically heterogeneous group of disorders of neurodegenerative origin, which result in degeneration of lower (LMNs) and/or upper motor neurons (UMNs). Neurodegenerative MNDs include pure hereditary spastic paraplegia (HSP), which involves specific degeneration of UMNs, leading to progressive spasticity of the lower limbs. In contrast, spinal muscular atrophy (SMA) involves the specific degeneration of LMNs, with symmetrical muscle weakness and atrophy. Amyotrophic lateral sclerosis (ALS), the most common adult-onset MND, is characterized by the degeneration of both UMNs and LMNs, leading to progressive muscle weakness, atrophy, and spasticity. A review of the comparative neuroanatomy of the human and zebrafish motor systems showed that, while the zebrafish was a homologous model for LMN disorders, such as SMA, it was only partially relevant in the case of UMN disorders, due to the absence of corticospinal and rubrospinal tracts in its central nervous system. Even considering the limitation of this model to fully reproduce the human UMN disorders, zebrafish offer an excellent alternative vertebrate model for the molecular and genetic dissection of MND mechanisms. Its advantages include the conservation of genome and physiological processes and applicable in vivo tools, including easy imaging, loss or gain of function methods, behavioral tests to examine changes in motor activity, and the ease of simultaneous chemical/drug testing on large numbers of animals. This facilitates the assessment of the environmental origin of MNDs, alone or in combination with genetic traits and putative modifier genes. Positive hits obtained by phenotype-based small-molecule screening using zebrafish may potentially be effective drugs for treatment of human MNDs.

Microglia and motor neurons during disease progression in the SOD1G93A mouse model of amyotrophic lateral sclerosis: changes in arginase1 and inducible nitric oxide synthase

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease affecting the motor system. Although the etiology of the disease is not fully understood, microglial activation and neuroinflammation are thought to play a role in disease progression.

METHODS

We examined the immunohistochemical expression of two markers of microglial phenotype, the arginine-metabolizing enzymes inducible nitric oxide synthase (iNOS) and arginase1 (Arg1), in the spinal cord of a mouse model carrying an ALS-linked mutant human superoxide dismutase transgene (SOD1(G93A)) and in non-transgenic wild-type (WT) mice. Immunolabeling for iNOS and Arg1 was evaluated throughout disease progression (6 to 25 weeks), and correlated with body weight, stride pattern, wire hang duration and ubiquitin pathology. For microglia and motor neuron counts at each time point, SOD1(G93A) and WT animals were compared using an independent samples t-test. A Welch t-test correction was applied if Levene's test showed that the variance in WT and SOD1G93A measurements was substantially different.

RESULTS

Disease onset, measured as the earliest change in functional parameters compared to non-transgenic WT mice, occurred at 14 weeks of age in SOD1(G93A) mice. The ventral horn of the SOD1(G93A) spinal cord contained more microglia than WT from 14 weeks onwards. In SOD1(G93A) mice, Arg1-positive and iNOS-positive microglia increased 18-fold and 7-fold, respectively, between 10 and 25 weeks of age (endpoint) in the lumbar spinal cord, while no increase was observed in WT mice. An increasing trend of Arg1- and iNOS-expressing microglia was observed in the cervical spinal cords of SOD1(G93A) mice. Additionally, Arg1-negative motor neurons appeared to selectively decline in the spinal cord of SOD1(G93A) mice, suggesting that Arg1 may have a neuroprotective function.

CONCLUSIONS

This study suggests that the increase in spinal cord microglia occurs around and after disease onset and is preceded by cellular pathology. The results show that Arg1 and iNOS, thought to have opposing inflammatory properties, are upregulated in microglia during disease progression and that Arg1 in motor neurons may confer protection from disease processes. Further understanding of the neuroinflammatory response, and the Arg1/iNOS balance in motor neurons, may provide suitable therapeutic targets for ALS.

Clinical perspective on oxidative stress in sporadic amyotrophic lateral sclerosis

Sporadic amyotrophic lateral sclerosis (ALS) is one of the most devastating neurological diseases; most patients die within 3 to 4 years after symptom onset. Oxidative stress is a disturbance in the pro-oxidative/antioxidative balance favoring the pro-oxidative state. Autopsy and laboratory studies in ALS indicate that oxidative stress plays a major role in motor neuron degeneration and astrocyte dysfunction. Oxidative stress biomarkers in cerebrospinal fluid, plasma, and urine are elevated, suggesting that abnormal oxidative stress is generated outside of the central nervous system. Our review indicates that agricultural chemicals, heavy metals, military service, professional sports, excessive physical exertion, chronic head trauma, and certain foods might be modestly associated with ALS risk, with a stronger association between risk and smoking. At the cellular level, these factors are all involved in generating oxidative stress. Experimental studies indicate that a combination of insults that induce modest oxidative stress can exert additive deleterious effects on motor neurons, suggesting that multiple exposures in real-world environments are important. As the disease progresses, nutritional deficiency, cachexia, psychological stress, and impending respiratory failure may further increase oxidative stress. Moreover, accumulating evidence suggests that ALS is possibly a systemic disease. Laboratory, pathologic, and epidemiologic evidence clearly supports the hypothesis that oxidative stress is central in the pathogenic process, particularly in genetically susceptive individuals. If we are to improve ALS treatment, well-designed biochemical and genetic epidemiological studies, combined with a multidisciplinary research approach, are needed and will provide knowledge crucial to our understanding of ALS etiology, pathophysiology, and prognosis.

Acute stimulation of transplanted neurons improves motoneuron survival, axon growth, and muscle reinnervation

Few options exist for treatment of pervasive motoneuron death after spinal cord injury or in neurodegenerative diseases such as amyotrophic lateral sclerosis. Local transplantation of embryonic motoneurons into an axotomized peripheral nerve is a promising approach to arrest the atrophy of denervated muscles; however, muscle reinnervation is limited by poor motoneuron survival. The aim of the present study was to test whether acute electrical stimulation of transplanted embryonic neurons promotes motoneuron survival, axon growth, and muscle reinnervation. The sciatic nerve of adult Fischer rats was transected to mimic the widespread denervation seen after disease or injury. Acutely dissociated rat embryonic ventral spinal cord cells were transplanted into the distal tibial nerve stump as a neuron source for muscle reinnervation. Immediately post-transplantation, the cells were stimulated at 20 Hz for 1 h. Other groups were used to control for the cell transplantation and stimulation. When neurons were stimulated acutely, there were significantly more neurons, including cholinergic neurons, 10 weeks after transplantation. This led to enhanced numbers of myelinated axons, reinnervation of more muscle fibers, and more medial and lateral gastrocnemius muscles were functionally connected to the transplant. Reinnervation reduced muscle atrophy significantly. These data support the concept that electrical stimulation rescues transplanted motoneurons and facilitates muscle reinnervation.

Acidotoxicity and acid-sensing ion channels contribute to motoneuron degeneration

Amyotrophic lateral sclerosis (ALS) is a fatal neurological condition with no cure. Mitochondrial dysfunction, Ca(2+) overloading and local hypoxic/ischemic environments have been implicated in the pathophysiology of ALS and are conditions that may initiate metabolic acidosis in the affected tissue. We tested the hypothesis that acidotoxicity and acid-sensing ion channels (ASICs) are involved in the pathophysiology of ALS. We found that motoneurons were selectively vulnerable to acidotoxicity in vitro, and that acidotoxicity was partially reduced in asic1a-deficient motoneuron cultures. Cross-breeding of SOD1(G93A) ALS mice with asic1a-deficient mice delayed the onset and progression of motor dysfunction in SOD1 mice. Interestingly, we also noted a strong increase in ASIC2 expression in motoneurons of SOD1 mice and sporadic ALS patients during disease progression. Pharmacological pan-inhibition of ASIC channels with the lipophilic amiloride derivative, 5-(N,N-dimethyl)-amiloride hydrochloride, potently protected cultured motoneurons against acidotoxicity, and, given post-symptom onset, significantly improved lifespan, motor performance and motoneuron survival in SOD1 mice. Together, our data provide strong evidence for the involvement of acidotoxicity and ASIC channels in motoneuron degeneration, and highlight the potential of ASIC inhibitors as a new treatment approach for ALS.

Parental age and the risk of amyotrophic lateral sclerosis

Sporadic ALS is a multifactorial disease for which there are probably multiple genetic risk factors. An association with increased parental age might suggest there is a role for specific (epi)genetic changes. Previous studies have shown conflicting results on the association between parental age and the risk of ALS. A large, population based study might help in the search for specific (epi)genetic risk factors. We performed a population based, case-control study in the Netherlands. Date of birth of both mother and father was retrieved from the National Register. Multivariate logistic regression analysis was performed in 769 patients with sporadic ALS, 49 patients with a hexanucleotide repeat expansion in C9orf72, and 1929 age-, gender- and geographically-matched controls. Multivariate analyses showed no difference in either paternal or maternal age at delivery (adjusted for age of subject, age of other parent at delivery, and level of education) in patients with sporadic ALS, nor in patients with a hexanucleotide repeat expansion in C9orf72 compared to controls. In conclusion, parental age was not associated with an increased risk of ALS in our study. (Epi)genetic alterations that are associated with increased parental age are not, therefore, likely to contribute to the aetiology of sporadic ALS.

Endogenous female reproductive hormones and the risk of amyotrophic lateral sclerosis

The pathogenesis of amyotrophic lateral sclerosis (ALS) is considered to be multifactorial. Several epidemiological studies showed a lower incidence of ALS in women than in men. This suggests a possible protective effect of female reproductive hormones. The aim of this study was to investigate the association between female reproductive hormones and ALS. We performed a population-based, case-control study in the Netherlands between 1st January 2006 and 1st December 2009. Only women with a natural menopause were included in the analysis. A total of 209 (85 %) of 246 female patients and 672 (93 %) of 719 controls returned a questionnaire on reproductive history to calculate the reproductive time-span and lifetime endogenous estrogen exposure (calculated by subtracting the duration of pregnancies and of oral contraceptive use, and the number of post-ovulatory weeks from the reproductive time-span). 131 (63 %) patients and 430 (64 %) age-matched, population-based controls had experienced a natural menopause. Multivariate analysis showed that increasing the reproductive time-span by a year decreases the risk of ALS with an OR of 0.95 (p = 0.005). Each year longer reproductive time-span [HR 0.90 (p = 0.01)] and lifetime endogenous estrogen exposure [HR 0.96 (p = 0.025)] were associated with a longer survival of ALS patients. The positive association of a longer reproductive time-span and susceptibility and survival of ALS might imply that longer exposure to female reproductive hormones has a neuroprotective effect on motor neurons.

Smoking, alcohol consumption, and the risk of amyotrophic lateral sclerosis: a population-based study

Smoking has been posited as a possible risk factor for amyotrophic lateral sclerosis (ALS), but large population-based studies of patients with incident disease are still needed. The authors performed a population-based case-control study in the Netherlands between 2006 and 2009, including 494 patients with incident ALS and 1,599 controls. To prove the relevance of population-based incidence cohorts in case-control studies, the authors compared results with those from cohorts including patients with prevalent ALS and referral patients. Subjects were sent a questionnaire. Multivariate analyses showed an increased risk of ALS among current smokers (odds ratio = 1.38, 95% confidence interval (CI): 1.02, 1.88) in the incident patient group only. Cox regression models showed that current smoking was also independently associated with shorter survival (hazard ratio = 1.51, 95% CI: 1.07, 2.15), explaining the lack of association in the prevalent and referral patient groups. Current alcohol consumption was associated with a reduced risk of ALS (incident patient group: odds ratio = 0.52, 95% CI: 0.40, 0.75). These findings indicate that current smoking is associated with an increased risk of ALS, as well as a worse prognosis, and alcohol consumption is associated with a reduced risk of ALS, further corroborating the role of lifestyle factors in the pathogenesis of ALS. The importance of population-based incident patient cohorts in identifying risk factors is highlighted by this study.

ALSoD: A user-friendly online bioinformatics tool for amyotrophic lateral sclerosis genetics

Amyotrophic lateral sclerosis (ALS) is the commonest adult onset motor neuron disease, with a peak age of onset in the seventh decade. With advances in genetic technology, there is an enormous increase in the volume of genetic data produced, and a corresponding need for storage, analysis, and interpretation, particularly as our understanding of the relationships between genotype and phenotype mature. Here, we present a system to enable this in the form of the ALS Online Database (ALSoD at http://alsod.iop.kcl.ac.uk), a freely available database that has been transformed from a single gene storage facility recording mutations in the SOD1 gene to a multigene ALS bioinformatics repository and analytical instrument combining genotype, phenotype, and geographical information with associated analysis tools. These include a comparison tool to evaluate genes side by side or jointly with user configurable features, a pathogenicity prediction tool using a combination of computational approaches to distinguish variants with nonfunctional characteristics from disease-associated mutations with more dangerous consequences, and a credibility tool to enable ALS researchers to objectively assess the evidence for gene causation in ALS. Furthermore, integration of external tools, systems for feedback, annotation by users, and two-way links to collaborators hosting complementary databases further enhance the functionality of ALSoD.

Common pathways of autoimmune inflammatory myopathies and genetic neuromuscular disorders

It has been shown that many hereditary motor neuron diseases are caused by mutation of RNA processing enzymes. Survival of motor neuron 1 (SMN1) is well-known as a causative gene for spinal muscular atrophy (SMA) and mutations of glycyl- and tyrosyl-tRNA synthetases are identified as a cause of distal SMA and Charcot-Marie-Tooth disease. Why and how the dysfunction of these ubiquitously expressed genes involved in RNA processing can cause a specific neurological disorder is not well understood. Interestingly, SMN complex has been identified recently as a new target of autoantibodies in polymyositis (PM). Autoantibodies in systemic rheumatic diseases are clinically useful biomarkers associated with a particular diagnosis, subset of a disease, or certain clinical characteristics. Many autoantibodies produced in patients with polymyositis/dermatomyositis (PM/DM) target RNA-protein complexes such as aminoacyl tRNA synthetases. It is interesting to note these same RNA-protein complexes recognized by autoantibodies in PM/DM are also responsible for genetic neuromuscular disease. Certain RNA-protein complexes are also targets of autoantibodies in paraneoplastic neurological disorders. Thus, there are several interesting associations between RNA-processing enzymes and neuromuscular disorders. Although pathogenetic roles of autoantibodies to intracellular antigens are generally considered unlikely, understanding the mechanisms of antigen selection in a particular disease and specific neurological symptoms caused by disruption of ubiquitous RNA-processing enzyme may help identify a common path in genetic neuromuscular disorders and autoimmunity in inflammatory myopathies.

Evidence for an oligogenic basis of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder with a substantial heritable component. In pedigrees affected by its familial form, incomplete penetrance is often observed. We hypothesized that this could be caused by a complex inheritance of risk variants in multiple genes. Therefore, we screened 111 familial ALS (FALS) patients from 97 families, and large cohorts of sporadic ALS (SALS) patients and control subjects for mutations in TAR DNA-binding protein (TARDBP), fused in sarcoma/translated in liposarcoma (FUS/TLS), superoxide dismutase-1 (SOD1), angiogenin (ANG) and chromosome 9 open reading frame 72 (C9orf72). Mutations were identified in 48% of FALS families, 8% of SALS patients and 0.5% of control subjects. In five of the FALS families, we identified multiple mutations in ALS-associated genes. We detected FUS/TLS and TARDBP mutations in combination with ANG mutations, and C9orf72 repeat expansions with TARDBP, SOD1 and FUS/TLS mutations. Statistical analysis demonstrated that the presence of multiple mutations in FALS is in excess of what is to be expected by chance (P = 1.57 × 10(-7)). The most compelling evidence for an oligogenic basis was found in individuals with a p.N352S mutation in TARDBP, detected in five FALS families and three apparently SALS patients. Genealogical and haplotype analyses revealed that these individuals shared a common ancestor. We obtained DNA of 14 patients with this TARDBP mutation, 50% of whom had an additional mutation (ANG, C9orf72 or homozygous TARDBP). Hereby, we provide evidence for an oligogenic aetiology of ALS. This may have important implications for the interpretation of whole exome/genome experiments designed to identify new ALS-associated genes and for genetic counselling, especially of unaffected family members.

Early functional deficit and microglial disturbances in a mouse model of amyotrophic lateral sclerosis

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by selective motoneurons degeneration. There is today no clear-cut pathogenesis sequence nor any treatment. However growing evidences are in favor of the involvement, besides neurons, of several partners such as glia and muscles. To better characterize the time course of pathological events in an animal model that recapitulates human ALS symptoms, we investigated functional and cellular characteristics of hSOD1(G93A) mice.

METHODS AND FINDINGS

We have evaluated locomotor function of hSOD1(G93A) mice through dynamic walking patterns and spontaneous motor activity analysis. We detected early functional deficits that redefine symptoms onset at 60 days of age, i.e. 20 days earlier than previously described. Moreover, sequential combination of these approaches allows monitoring of motor activity up to disease end stage. To tentatively correlate early functional deficit with cellular alterations we have used flow cytometry and immunohistochemistry approaches to characterize neuromuscular junctions, astrocytes and microglia. We show that (1) decrease in neuromuscular junction's number correlates with motor impairment, (2) astrocytes number is not altered at pre- and early-symptomatic ages but intraspinal repartition is modified at symptoms onset, and (3) microglia modifications precede disease onset. At pre-symptomatic age, we show a decrease in microglia number whereas at onset of the disease two distinct microglia sub-populations emerge.

CONCLUSIONS

In conclusion, precise motor analysis updates the onset of the disease in hSOD1(G93A) mice and allows locomotor monitoring until the end stage of the disease. Early functional deficits coincide with alterations of neuromuscular junctions. Importantly, we identify different sets of changes in microglia before disease onset as well as at early-symptomatic stage. This finding not only brings a new sequence of cellular events in the natural history of the disease, but it may also provide clues in the search for biomarkers of the disease, and potential therapeutic targets.

A yeast functional screen predicts new candidate ALS disease genes

Amyotrophic lateral sclerosis (ALS) is a devastating and universally fatal neurodegenerative disease. Mutations in two related RNA-binding proteins, TDP-43 and FUS, that harbor prion-like domains, cause some forms of ALS. There are at least 213 human proteins harboring RNA recognition motifs, including FUS and TDP-43, raising the possibility that additional RNA-binding proteins might contribute to ALS pathogenesis. We performed a systematic survey of these proteins to find additional candidates similar to TDP-43 and FUS, followed by bioinformatics to predict prion-like domains in a subset of them. We sequenced one of these genes, TAF15, in patients with ALS and identified missense variants, which were absent in a large number of healthy controls. These disease-associated variants of TAF15 caused formation of cytoplasmic foci when expressed in primary cultures of spinal cord neurons. Very similar to TDP-43 and FUS, TAF15 aggregated in vitro and conferred neurodegeneration in Drosophila, with the ALS-linked variants having a more severe effect than wild type. Immunohistochemistry of postmortem spinal cord tissue revealed mislocalization of TAF15 in motor neurons of patients with ALS. We propose that aggregation-prone RNA-binding proteins might contribute very broadly to ALS pathogenesis and the genes identified in our yeast functional screen, coupled with prion-like domain prediction analysis, now provide a powerful resource to facilitate ALS disease gene discovery.

Genetic strategies to study TDP-43 in rodents and to develop preclinical therapeutics for amyotrophic lateral sclerosis

The neuropathological hallmark of the majority of amyotrophic lateral sclerosis (ALS) and a class of frontotemporal lobar degeneration is ubiquitinated cytoplasmic aggregates composed of transactive response DNA binding protein 43 kDa (TDP-43). Genetic manipulation of TDP-43 in animal models has been used to study the protein's role in pathogenesis. Transgenic rodents for TDP-43 have recapitulated key aspects of ALS such as paralysis, loss of spinal motor neurons and muscle atrophy. Viral vectors are an alternate approach to express pathological proteins in animals. Use of the recombinant adeno-associated virus vector serotype 9 has permitted widespread transgene expression throughout the central nervous system after intravenous administration. Expressing TDP-43 in rats with this method produced a phenotype that was consistent with and similar to TDP-43 transgenic lines. Increased levels of TDP-43 in the nucleus are toxic to neurons and sufficient to produce ALS-like symptoms. Animal models based on TDP-43 will address the relationships between TDP-43 expression levels, pathology, neuronal loss, muscle atrophy, motor function and causative mechanisms of disease. New targets that modify TDP-43 function, or targets from previous ALS models and other models of spinal cord diseases, could be tested for efficacy in the recent rodent models of ALS based on TDP-43. The vector approach could be an important therapeutic channel because the entire spinal cord can be affected from a one-time peripheral administration.

Spinal inhibitory interneuron pathology follows motor neuron degeneration independent of glial mutant superoxide dismutase 1 expression in SOD1-ALS mice

Motor neuron degeneration and skeletal muscle denervation are hallmarks of amyotrophic lateral sclerosis (ALS), but other neuron populations and glial cells are also involved in ALS pathogenesis. We examined changes in inhibitory interneurons in spinal cords of the ALS model low-copy Gurney G93A-SOD1 (G1del) mice and found reduced expression of markers of glycinergic and GABAergic neurons, that is, glycine transporter 2 (GlyT2) and glutamic acid decarboxylase (GAD65/67), specifically in the ventral horns of clinically affected mice. There was also loss of GlyT2 and GAD67 messenger RNA-labeled neurons in the intermediate zone. Ubiquitinated inclusions appeared in interneurons before 20 weeks of age, that is, after their development in motor neurons but before the onset of clinical signs and major motor neuron degeneration, which starts from 25 weeks of age. Because mutant superoxide dismutase 1 (SOD1) in glia might contribute to the pathogenesis, we also examined neuron-specific G93A-SOD1 mice; they also had loss of inhibitory interneuron markers in ventral horns and ubiquitinated interneuron inclusions. These data suggest that, in mutant SOD1-associated ALS, pathological changes may spread from motor neurons to interneuronsin a relatively early phase of the disease, independent of the presence of mutant SOD1 in glia. The degeneration of spinal inhibitory interneurons may in turn facilitate degeneration of motor neurons and contribute to disease progression.

ALS: focus on purinergic signalling

Amyotrophic lateral sclerosis (ALS) is one of the most common neuromuscular diseases. It is devastating and fatal, causing progressive paralysis of all voluntary muscles and eventually death, while sparing cognitive functions. A pathological hallmark of ALS is neuroinflammation mediated by non-neuronal cells in the nervous system, such as microglia and astrocytes that accelerate the disease progression. Scientists have neither found a unique key mechanism, nor an effective treatment against ALS, supposedly because it is a multi-factorial and multi-systemic disease. Extracellular purines and pyrimidines are widespread and powerful physiopathological molecules, signalling to most cell types and directing cell-to-cell communication networks. They are instrumental for instance for neurotransmission, muscle contraction and immune surveillance. Recent work has reported the crucial involvement of purinergic pathways in many neurodegenerative and neuroinflammatory diseases, comprising ALS. Especially P2 receptors for ATP, P1 receptors for adenosine, and nucleotide transporters were found to be modulated in ALS cells and tissues, playing a potential role in the disease. Given the composite cellular cross-talk occurring during ALS and the established action of extracellular purines/pyrimidines as neuron-to-glia alarm signal in the nervous system, a mutual query in these two fields should now be whether, how and when purinergic would meet ALS. In this review, we will highlight the early cellular and molecular purinergic cross-talk that participates to ALS etiopathology, with the conviction that better understanding of purinergic dynamics might provide original research perspectives, stimulate alternative disease modelling, and the design and testing of more powerful targeted therapeutics against this relentlessly progressive disorder.

Neuroinflammation in amyotrophic lateral sclerosis: role of glial activation in motor neuron disease

Neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis (ALS) are characterised by the appearance of reactive microglial and astroglial cells, a process referred to as neuroinflammation. In transgenic mouse models of mutant SOD1-associated familial ALS, reactive microglial cells and astrocytes actively contribute to the death of motor neurons. The biological processes that drive this glial reaction are complex and have both beneficial and deleterious effects on motor neurons. Therapeutic interventions targeting these cells are being explored. An improved understanding of the biological processes that cause neuroinflammation will help to define its medical importance and to identify the therapeutic potential of interfering with this reaction.

FUS transgenic rats develop the phenotypes of amyotrophic lateral sclerosis and frontotemporal lobar degeneration

Fused in Sarcoma (FUS) proteinopathy is a feature of frontotemporal lobar dementia (FTLD), and mutation of the fus gene segregates with FTLD and amyotrophic lateral sclerosis (ALS). To study the consequences of mutation in the fus gene, we created transgenic rats expressing the human fus gene with or without mutation. Overexpression of a mutant (R521C substitution), but not normal, human FUS induced progressive paralysis resembling ALS. Mutant FUS transgenic rats developed progressive paralysis secondary to degeneration of motor axons and displayed a substantial loss of neurons in the cortex and hippocampus. This neuronal loss was accompanied by ubiquitin aggregation and glial reaction. While transgenic rats that overexpressed the wild-type human FUS were asymptomatic at young ages, they showed a deficit in spatial learning and memory and a significant loss of cortical and hippocampal neurons at advanced ages. These results suggest that mutant FUS is more toxic to neurons than normal FUS and that increased expression of normal FUS is sufficient to induce neuron death. Our FUS transgenic rats reproduced some phenotypes of ALS and FTLD and will provide a useful model for mechanistic studies of FUS–related diseases.

Amyotrophic lateral sclerosis and frontotemporal lobar degeneration are two related diseases characterized by degeneration of selected groups of neuronal cells. Neither of these diseases has a clear cause, and both are incurable at present. Mutation of the fus gene has recently been linked to these two diseases. Here, we describe a novel rat model that expresses a mutated form of the human fus gene and manifests the phenotypes and pathological features of amyotrophic lateral sclerosis and frontotemporal lobar degeneration. Establishment of this FUS transgenic rat model will allow not only for mechanistic study of FUS–related diseases, but also for quick development of therapies for these devastating diseases.

Drosophila melanogaster in the study of human neurodegeneration

Human neurodegenerative diseases are devastating illnesses that predominantly affect elderly people. The majority of the diseases are associated with pathogenic oligomers from misfolded proteins, eventually causing the formation of aggregates and the progressive loss of neurons in the brain and nervous system. Several of these proteinopathies are sporadic and the cause of pathogenesis remains elusive. Heritable forms are associated with genetic defects, suggesting that the affected protein is causally related to disease formation and/or progression. The limitations of human genetics, however, make it necessary to use model systems to analyse affected genes and pathways in more detail. During the last two decades, research using the genetically amenable fruitfly has established Drosophila melanogaster as a valuable model system in the study of human neurodegeneration. These studies offer reliable models for Alzheimer's, Parkinson's, and motor neuron diseases, as well as models for trinucleotide repeat expansion diseases, including ataxias and Huntington's disease. As a result of these studies, several signalling pathways including phosphatidylinositol 3-kinase (PI3K)/Akt and target of rapamycin (TOR), c-Jun N-terminal kinase (JNK) and bone morphogenetic protein (BMP) signalling, have been shown to be deregulated in models of proteinopathies, suggesting that two or more initiating events may trigger disease formation in an age-related manner. Moreover, these studies also demonstrate that the fruitfly can be used to screen chemical compounds for their potential to prevent or ameliorate the disease, which in turn can directly guide clinical research and the development of novel therapeutic strategies for the treatment of human neurodegenerative diseases.

De novo truncating FUS gene mutation as a cause of sporadic amyotrophic lateral sclerosis

Mutations in the gene encoding fused in sarcoma (FUS) were recently identified as a novel cause of amyotrophic lateral sclerosis (ALS), emphasizing the genetic heterogeneity of ALS. We sequenced the genes encoding superoxide dismutase (SOD1), TAR DNA-binding protein 43 (TARDBP) and FUS in 99 sporadic and 17 familial ALS patients ascertained at Mayo Clinic. We identified two novel mutations in FUS in two out of 99 (2.0%) sporadic ALS patients and established the de novo occurrence of one FUS mutation. In familial patients, we identified three (17.6%) SOD1 mutations, while FUS and TARDBP mutations were excluded. The de novo FUS mutation (g.10747A>G; IVS13-2A>G) affects the splice-acceptor site of FUS intron 13 and was shown to induce skipping of FUS exon 14 leading to the C-terminal truncation of FUS (p.G466VfsX14). Subcellular localization studies showed a dramatic increase in the cytoplasmic localization of FUS and a reduction of normal nuclear expression in cells transfected with truncated compared to wild-type FUS. We further identified a novel in-frame insertion/deletion mutation in FUS exon 12 (p.S402_P411delinsGGGG) which is predicted to expand a conserved poly-glycine motif. Our findings extend the mutation spectrum in FUS leading to ALS and describe the first de novo mutation in FUS.

A case of amyotrophic lateral sclerosis presented as oropharyngeal Dysphagia

Amyotrophic lateral sclerosis is a rare disease. It is a fatal neurodegenerative disease characterized by progressive muscular paralysis reflecting degeneration of motor neurons which leads to muscle weakness and muscle wasting. Respiratory failure limits survival to 2-5 years after disease onset. Several clinical manifestations including dysphagia can result in reductions in both the quality of life and life expectancy. Dysphagia occurs at onset in about one third of case, although generally it occurs in later stage of the disease. Evaluation of dysphagia includes video-fluoroscopic swallow study, radiological esophagogram, flexible endoscopic examination, ultrasound examination, conventional manometry and electromyography. We report a case of amyotrophic lateral sclerosis in a 54-year-old man presenting oropharyngeal dysphagia which was diagnosed by high resolution esophageal manometry presenting abnormality of the upper esophageal sphincter.

The neurobiology of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis is a degenerative disease affecting the motor neurons. In spite of our growing insights into its biology, it remains a lethal condition. The identification of the cause of several of the familial forms of ALS allowed generation of models to study this disease both in vitro and in vivo. Here, we summarize what is known about the pathogenic mechanisms of ALS induced by hereditary mutations, and attempt to identify the relevance of these findings for understanding the pathogenic mechanisms of the sporadic form of this disease.

ALS spinal neurons show varied and reduced mtDNA gene copy numbers and increased mtDNA gene deletions

Background

Spinal cord neurons of ALS patients demonstrate reduced cytochrome oxidase histochemical activity, and ALS spinal cord tissues have increased mitochondrial DNA (mtDNA) point mutations and depleted mtDNA levels. It is presently unknown whether mtDNA abnormalities are present in single human ALS neurons.

Results

Using laser capture microdissection (LCM) we isolated several hundred individual anterior spinal neurons from unfixed, frozen sections of 10 ALS and 7 age-matched CTL cervical spinal cords. DNA from each individual neuron was analyzed with multiplex qPCR for ND2, CO3, and ND4, three mitochondrial DNA genes encoding respiratory proteins. Scatterplots of individual spinal neuron results showed extensive heterogeneity of mtDNA gene levels across 4-5 orders of magnitude that were much more clustered in single Purkinje neurons isolated from CTL cerebella. Plots of ratios of ND4/ND2 and CO3/ND2 showed that many but not all ALS neurons from individuals contained low ratios of these mtDNA genes, implying greater abundances of mtDNA deletions in the major arc. Single CTL cerebellar Purkinje neurons did not contain high levels of apparent mtDNA deletions observed in anterior spinal neurons.

Conclusions

At the time of ALS subjects' deaths, many but not all surviving anterior neurons in their cervical spinal cords have reduced mtDNA gene levels and increased mtDNA deletion abundances that arise for unclear reasons. If these anterior spinal neuron mtDNA gene deficiencies contribute to bioenergetic impairments, reduced synaptic function and increased risk of degeneration, then introduction into mitochondria and expression of intact mtDNA, now available through use of recently developed recombinant human TFAM, may reverse the course of ALS.

AAV-mediated expression of wild-type and ALS-linked mutant VAPB selectively triggers death of motoneurons through a Ca2+-dependent ER-associated pathway

A dominant mutation in the gene coding for the vesicle-associated membrane protein-associated protein B (VAPB) was associated with amyotrophic lateral sclerosis, a fatal paralytic disorder characterized by the selective loss of motoneurons in the brain and spinal cord. Adeno-associated viral vectors that we show to transduce up to 90% of motoneurons in vitro were used to model VAPB-associated neurodegenerative process. We observed that Adeno-associated viral-mediated over-expression of both wild-type and mutated form of human VAPB selectively induces death of primary motoneurons, albeit with different kinetics. We provide evidence that ER stress and impaired homeostatic regulation of calcium (Ca(2+)) are implicated in the death process. Finally, we found that completion of the motoneuron death program triggered by the over-expression of wild-type and mutant VAPB implicates calpains, caspase 12 and 3. Our viral-based in vitro model, which recapitulates the selective vulnerability of motoneurons to the presence of mutant VAPB and also to VAPB gene dosage effect, identifies aberrant Ca(2+) signals and ER-derived death pathways as important events in the motoneuron degenerative process.

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-α] 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.

Increased expression and activation of cytosolic phospholipase A2 in the spinal cord of patients with sporadic amyotrophic lateral sclerosis

Compelling evidence identifies a link between cytotoxic effects of cytosolic phospholipase A2 (cPLA2) activity and neuron death in cell cultures. cPLA2 catalyzes the hydrolysis of membrane phospholipids to produce and release arachidonate, leading to plasma membrane injury, inflammatory response and subsequent cell death. To assess a role for cPLA2 in the pathomechanism of amyotrophic lateral sclerosis (ALS), we performed immunohistochemical, immunoblot, and densitometric analyses of cPLA2 and its active form phosphorylated at S505 (p-cPLA2) on spinal cords obtained at autopsy from ten sporadic ALS patients and ten age-matched controls. On sections, immunoreactivities for cPLA2 and p-cPLA2 were distinct and localized in almost all of the motor neurons, reactive astrocytes, and activated microglia in the ALS cases, while immunoreactivities were only weak or not at all observed in neurons and glia in the control cases. On immunoblots, both the cPLA2/β-actin density ratio and the p-cPLA2/cPLA2 density ratio were significantly increased in the ALS group compared to the control group. There was no significant link between the densitometric data and the clinical phenotypes, age at death or disease duration of the ALS patients. These results provide in vivo evidence for increased expression and activation of cPLA2 in motor neurons, reactive astrocytes, and activated microglia in ALS, suggesting occurrence of arachidonate cascade-induced motor neuron death via cell-autonomous and/or non-cell-autonomous mechanisms.