Neuroprotective effect of ultra-high dose methylcobalamin in wobbler mouse model of amyotrophic lateral sclerosis

Patients' experiences with methylcobalamin injections in amyotrophic lateral sclerosis

BACKGROUND AND OBJECTIVES

Amyotrophic lateral sclerosis (ALS) is a progressive motor neuron disease with no definitive treatment. Vitamin B12 is not a Food and Drug Administration-approved treatment in the United States, although it has been prescribed off-label as ultra-high-dose methylcobalamin, which has been shown to be safe and effective in slowing functional decline in patients with ALS. This study evaluates the impact of Vitamin B12 injections on the quality of life of five patients.

METHODS

Semi-structured interviews were conducted with the patients and caregivers. The data was carefully read, coded, and organized into themes and sub-themes by two independent researchers.

RESULTS

The study found four themes and 11 subthemes from the data, including initial circumstances, administration of the injection, subjective experience with Vitamin B12, and outcomes and expectations. All participants recognized some benefits from Vitamin B12 injections, specifically increased energy, reduced fatigue, and improved balance. However, some patients had difficulty monitoring its specific effect due to the progressive nature of the disease.

DISCUSSION

The flexibility offered by this intervention is beneficial for patients with declining mobility and strength who wish to adapt their treatment to their schedule. This work is a modest call to fill the existing gap in the literature and push for more randomized controlled trials investigating and clarifying the effects of Vitamin B12 injections on disease progression, muscle function, and quality of life in a small but diverse pool of patients with ALS.

Therapeutic targeting of ALS pathways: Refocusing an incomplete picture

Numerous potential amyotrophic lateral sclerosis (ALS)-relevant pathways have been hypothesized and studied preclinically, with subsequent translation to clinical trial. However, few successes have been observed with only modest effects. Along with an improved but incomplete understanding of ALS as a neurodegenerative disease is the evolution of more sophisticated and diverse in vitro and in vivo preclinical modeling platforms, as well as clinical trial designs. We highlight proposed pathological pathways that have been major therapeutic targets for investigational compounds. It is likely that the failures of so many of these therapeutic compounds may not have occurred because of lack of efficacy but rather because of a lack of preclinical modeling that would help define an appropriate disease pathway, as well as a failure to establish target engagement. These challenges are compounded by shortcomings in clinical trial design, including lack of biomarkers that could predict clinical success and studies that are underpowered. Although research investments have provided abundant insights into new ALS-relevant pathways, most have not yet been developed more fully to result in clinical study. In this review, we detail some of the important, well-established pathways, the therapeutics targeting them, and the subsequent clinical design. With an understanding of some of the shortcomings in translational efforts over the last three decades of ALS investigation, we propose that scientists and clinicians may choose to revisit some of these therapeutic pathways reviewed here with an eye toward improving preclinical modeling, biomarker development, and the investment in more sophisticated clinical trial designs.

Farrerol attenuates glutamate-induced apoptosis in HT22 cells via the Nrf2/heme oxygenase-1 pathway

Farrerol is a flavonoid found in plants with a wide range of pharmacological effects, including protection and enhancement of nerve cell function, as well as antioxidant and antibacterial properties, among others. Neurodegenerative diseases are irreversible neurological disorders resulting from the loss of neuronal cells in the brain and spinal cord. In this experiment, we investigated the neuroprotective and antioxidant effects of farrerol on glutamate-induced HT22 cells. Our results showed that farrerol inhibited reactive oxygen species expression, apoptosis, mitochondrial damage, and the activation of caspases 3 and 9 in HT22 cells induced by glutamate. Additionally, farrerol potentially regulated the Nrf2/heme oxygenase-1 (HO-1) signaling pathway, as it attenuated the nuclear translocation of Nrf2 and promoted the expression of HO-1. These findings suggest that farrerol has potential as a new therapeutic option.

Current State and Future Directions in the Therapy of ALS

Amyotrophic lateral sclerosis (ALS) is a rapidly progressive neurodegenerative disorder affecting upper and lower motor neurons, with death resulting mainly from respiratory failure three to five years after symptom onset. As the exact underlying causative pathological pathway is unclear and potentially diverse, finding a suitable therapy to slow down or possibly stop disease progression remains challenging. Varying by country Riluzole, Edaravone, and Sodium phenylbutyrate/Taurursodiol are the only drugs currently approved in ALS treatment for their moderate effect on disease progression. Even though curative treatment options, able to prevent or stop disease progression, are still unknown, recent breakthroughs, especially in the field of targeting genetic disease forms, raise hope for improved care and therapy for ALS patients. In this review, we aim to summarize the current state of ALS therapy, including medication as well as supportive therapy, and discuss the ongoing developments and prospects in the field. Furthermore, we highlight the rationale behind the intense research on biomarkers and genetic testing as a feasible way to improve the classification of ALS patients towards personalized medicine.

Therapeutic Potential of Natural Compounds in Neurodegenerative Diseases: Insights from Clinical Trials

Neurodegenerative diseases are caused by the gradual loss of neurons' function. These neurological illnesses remain incurable, and current medicines only alleviate the symptoms. Given the social and economic burden caused by the rising frequency of neurodegenerative diseases, there is an urgent need for the development of appropriate therapeutics. Natural compounds are gaining popularity as alternatives to synthetic drugs due to their neuroprotective properties and higher biocompatibility. While natural compounds' therapeutic effects for neurodegenerative disease treatment have been investigated in numerous in vitro and in vivo studies, only few have moved to clinical trials. This article provides the first systematic review of the clinical trials evaluating natural compounds' safety and efficacy for the treatment of the five most prevalent neurodegenerative disorders: Alzheimer's disease, Parkinson's disease, multiple sclerosis, amyotrophic lateral sclerosis, and Huntington's disease.

ROS scavengers decrease γH2ax spots in motor neuronal nuclei of ALS model mice in vitro

Background: Amyotrophic lateral sclerosis (ALS) is an incurable neurodegenerative disease characterized by the loss of motor neurons in cerebral cortex, brainstem and spinal cord. Numerous studies have demonstrated signs of oxidative stress in postmortem neuronal tissue, cerebrospinal fluid, plasma and urine of ALS patients, without focusing on the specific processes within motor neurons. Thus, we aimed to investigate the relevance of reactive oxygen species (ROS) detoxification mechanisms and its consequences on the formation of toxic/lethal DNA double strand breaks (DSBs) in the ALS model of the Wobbler mouse.

Methods: Live cell imaging in dissociated motor neuronal cultures was used to investigate the production of ROS using Dihydroethidium (DHE). The expression levels of ROS detoxifying molecules were investigated by qPCR as well as Western blots. Furthermore, the expression levels of DNA damage response proteins p53bp1 and H2ax were investigated using qPCR and immunofluorescence staining. Proof-of-principle experiments using ROS scavengers were performed in vitro to decipher the influence of ROS on the formation of DNA double strand breaks quantifying the γH2ax spots formation.

Results: Here, we verified an elevated ROS-level in spinal motor neurons of symptomatic Wobbler mice in vitro. As a result, an increased number of DNA damage response proteins p53bp1 and γH2ax in dissociated motor neurons of the spinal cord of Wobbler mice was observed. Furthermore, we found a significantly altered expression of several antioxidant molecules in the spinal cord of Wobbler mice, suggesting a deficit in ROS detoxification mechanisms. This hypothesis could be verified by using ROS scavenger molecules in vitro to reduce the number of γH2ax foci in dissociated motor neurons and thus counteract the harmful effects of ROS.

Conclusion: Our data indicate that maintenance of redox homeostasis may play a key role in the therapy of the neurodegenerative disease ALS. Our results underline a necessity for multimodal treatment approaches to prolong the average lifespan of motor neurons and thus slow down the progression of the disease, since a focused intervention in one pathomechanism seems to be insufficient in ALS therapy.

Efficacy and Safety of Ultrahigh-Dose Methylcobalamin in Early-Stage Amyotrophic Lateral Sclerosis: A Randomized Clinical Trial

Importance

The effectiveness of currently approved drugs for amyotrophic lateral sclerosis (ALS) is restricted; there is a need to develop further treatments. Initial studies have shown ultrahigh-dose methylcobalamin to be a promising agent.

Objective

To validate the efficacy and safety of ultrahigh-dose methylcobalamin for patients with ALS enrolled within 1 year of onset.

Design, Setting, and Participants

This was a multicenter, placebo-controlled, double-blind, randomized phase 3 clinical trial with a 12-week observation and 16-week randomized period, conducted from October 17, 2017, to September 30, 2019. Patients were recruited from 25 neurology centers in Japan; those with ALS diagnosed within 1 year of onset by the updated Awaji criteria were initially enrolled. Of those, patients fulfilling the following criteria after 12-week observation were eligible for randomization: 1- or 2-point decrease in the Revised Amyotrophic Lateral Sclerosis Functional Rating Scale (ALSFRS-R) total score, a percent forced vital capacity greater than 60%, no history of noninvasive respiratory support and tracheostomy, and being ambulatory. The target participant number was 64 in both the methylcobalamin and placebo groups. Patients were randomly assigned through an electronic web-response system to methylcobalamin or placebo.

Interventions

Intramuscular injection of methylcobalamin (50-mg dose) or placebo twice weekly for 16 weeks.

Main Outcomes and Measures

The primary end point was change in ALSFRS-R total score from baseline to week 16 in the full analysis set.

Results

A total of 130 patients (mean [SD] age, 61.0 [11.7] years; 74 men [56.9%]) were randomly assigned to methylcobalamin or placebo (65 each). A total of 129 patients were eligible for the full analysis set, and 126 completed the double-blind stage. Of these, 124 patients proceeded to the open-label extended period. The least square means difference in ALSFRS-R total score at week 16 of the randomized period was 1.97 points greater with methylcobalamin than placebo (-2.66 vs -4.63; 95% CI, 0.44-3.50; P = .01). The incidence of adverse events was similar between the 2 groups.

Conclusions and Relevance

Results of this randomized clinical trial showed that ultrahigh-dose methylcobalamin was efficacious in slowing functional decline in patients with early-stage ALS and with moderate progression rate and was safe to use during the 16-week treatment period.

Trial Registration

ClinicalTrials.gov Identifier: NCT03548311.

Comprehensive Research on Past and Future Therapeutic Strategies Devoted to Treatment of Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a rapidly debilitating fatal neurodegenerative disorder, causing muscle atrophy and weakness, which leads to paralysis and eventual death. ALS has a multifaceted nature affected by many pathological mechanisms, including oxidative stress (also via protein aggregation), mitochondrial dysfunction, glutamate-induced excitotoxicity, apoptosis, neuroinflammation, axonal degeneration, skeletal muscle deterioration and viruses. This complexity is a major obstacle in defeating ALS. At present, riluzole and edaravone are the only drugs that have passed clinical trials for the treatment of ALS, notwithstanding that they showed modest benefits in a limited population of ALS. A dextromethorphan hydrobromide and quinidine sulfate combination was also approved to treat pseudobulbar affect (PBA) in the course of ALS. Globally, there is a struggle to prevent or alleviate the symptoms of this neurodegenerative disease, including implementation of antisense oligonucleotides (ASOs), induced pluripotent stem cells (iPSCs), CRISPR-9/Cas technique, non-invasive brain stimulation (NIBS) or ALS-on-a-chip technology. Additionally, researchers have synthesized and screened new compounds to be effective in ALS beyond the drug repurposing strategy. Despite all these efforts, ALS treatment is largely limited to palliative care, and there is a strong need for new therapeutics to be developed. This review focuses on and discusses which therapeutic strategies have been followed so far and what can be done in the future for the treatment of ALS.

Nutrient Effects on Motor Neurons and the Risk of Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is an incurable chronic progressive neurodegenerative disease with the progressive degeneration of motor neurons in the motor cortex and lower motor neurons in the spinal cord and the brain stem. The etiology and pathogenesis of ALS are being actively studied, but there is still no single concept. The study of ALS risk factors can help to understand the mechanism of this disease development and, possibly, slow down the rate of its progression in patients and also reduce the risk of its development in people with a predisposition toward familial ALS. The interest of researchers and clinicians in the protective role of nutrients in the development of ALS has been increasing in recent years. However, the role of some of them is not well-understood or disputed. The objective of this review is to analyze studies on the role of nutrients as environmental factors affecting the risk of developing ALS and the rate of motor neuron degeneration progression.

METHODS

We searched the PubMed, Springer, Clinical keys, Google Scholar, and E-Library databases for publications using keywords and their combinations. We analyzed all the available studies published in 2010-2020.

DISCUSSION

We analyzed 39 studies, including randomized clinical trials, clinical cases, and meta-analyses, involving ALS patients and studies on animal models of ALS. This review demonstrated that the following vitamins are the most significant protectors of ALS development: vitamin B12, vitamin E > vitamin C > vitamin B1, vitamin B9 > vitamin D > vitamin B2, vitamin B6 > vitamin A, and vitamin B7. In addition, this review indicates that the role of foods with a high content of cholesterol, polyunsaturated fatty acids, urates, and purines plays a big part in ALS development.

CONCLUSION

The inclusion of vitamins and a ketogenic diet in disease-modifying ALS therapy can reduce the progression rate of motor neuron degeneration and slow the rate of disease progression, but the approach to nutrient selection must be personalized. The roles of vitamins C, D, and B7 as ALS protectors need further study.

A perspective on therapies for amyotrophic lateral sclerosis: can disease progression be curbed?

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease involving both upper and lower motor neurons, leading to paralysis and eventually death. Symptomatic treatments such as inhibition of salivation, alleviation of muscle cramps, and relief of spasticity and pain still play an important role in enhancing the quality of life. To date, riluzole and edaravone are the only two drugs approved by the Food and Drug Administration for the treatment of ALS in a few countries. While there is adequate consensus on the modest efficacy of riluzole, there are still open questions concerning the efficacy of edaravone in slowing the disease progression. Therefore, identification of novel therapeutic strategies is urgently needed. Impaired autophagic process plays a critical role in ALS pathogenesis. In this review, we focus on therapies modulating autophagy in the context of ALS. Furthermore, stem cell therapies, gene therapies, and newly-developed biomaterials have great potentials in alleviating neurodegeneration, which might halt the disease progression. In this review, we will summarize the current and prospective therapies for ALS.

Association Between Vitamins and Amyotrophic Lateral Sclerosis: A Center-Based Survey in Mainland China

To date, conflicting results about the role of vitamins in amyotrophic lateral sclerosis (ALS) have been reported along with a lack of systematic studies on all types of serum vitamins in patients with ALS. Moreover, extensive studies have been conducted on vitamins in other neurodegenerative diseases; however, whether serum vitamin alterations in ALS are similar to those in other neurodegenerative diseases remains unclear. Therefore, we performed a study involving a large Chinese cohort of patients with ALS to address this gap. In this study, 202 patients with ALS, 214 with a neurodegenerative disease that mimicked ALS (mimics), and 208 healthy controls were enrolled. Serum vitamins of all subjects were examined under fasting state in Clinical Laboratory. As a result, we found that higher vitamin A and E levels and lower vitamin B2, B9, and C levels were in patients with ALS compared to healthy controls, and that high vitamin A and E levels, and low vitamin B2, B9, and C levels were associated with an increased risk for ALS. In addition, serum vitamin C was lower in early-onset ALS patients compared to those in late-onset ALS patients; however, there was no significant correlation between serum vitamins and age at onset, sites at onset, disease duration, or disease severity of ALS. We also found that patients with ALS showed similar vitamin alterations to mimics, with the exception of vitamin E. In summary, our study adds information to the literature on the role of vitamins in ALS and provides support for clinical guidance regarding dietary changes and vitamin supplements in patients with ALS.

Histamine beyond its effects on allergy: Potential therapeutic benefits for the treatment of Amyotrophic Lateral Sclerosis (ALS)

ALS currently remains a challenge despite many efforts in performing successful clinical trials and formulating therapeutic solutions. By learning from current failures and striving for success, scientists and clinicians are checking every possibility to search for missing hints and efficacious treatments. Because the disease is very complex and heterogeneous and, moreover, targeting not only motor neurons but also several different cell types including muscle, glial, and immune cells, the right answer to ALS is conceivably a multidrug strategy or the use of broad-spectrum molecules. The aim of the present work is to gather evidence about novel perspectives on ALS pathogenesis and to present recent and innovative paradigms for therapy. In particular, we describe how an old molecule possessing immunomodulatory and neuroprotective functions beyond its recognized effects on allergy, histamine, might have a renewed and far-reaching momentum in ALS.

Ultra-high-dose methylcobalamin in amyotrophic lateral sclerosis: a long-term phase II/III randomised controlled study

OBJECTIVE

To evaluate the efficacy and safety of intramuscular ultra-high-dose methylcobalamin in patients with amyotrophic lateral sclerosis (ALS).

METHODS

373 patients with ALS (El Escorial definite or probable; laboratory-supported probable; duration ≤36 months) were randomly assigned to placebo, 25 mg or 50 mg of methylcobalamin groups. The primary endpoints were the time interval to primary events (death or full ventilation support) and changes in the Revised ALS Functional Rating Scale (ALSFRS-R) score from baseline to week 182. Efficacy was also evaluated using post-hoc analyses in patients diagnosed early (entered ≤12 months after symptom onset).

RESULTS

No significant differences were detected in either primary endpoint (minimal p value=0.087). However, post-hoc analyses of methylcobalamin-treated patients diagnosed and entered early (≤12 months' duration) showed longer time intervals to the primary event (p<0.025) and less decreases in the ALSFRS-R score (p<0.025) than the placebo group. The incidence of treatment-related adverse events was similar and low in all groups.

CONCLUSION

Although ultra-high-dose methylcobalamin did not show significant efficacy in the whole cohort, this treatment may prolong survival and retard symptomatic progression without major side effects if started early.

TRIAL REGISTRATION NUMBER

NCT00444613.

Protein aggregation in cell biology: An aggregomics perspective of health and disease

Maintaining protein homeostasis (proteostasis) is essential for cellular health and is governed by a network of quality control machinery comprising over 800 genes. When proteostasis becomes imbalanced, proteins can abnormally aggregate or become mislocalized. Inappropriate protein aggregation and proteostasis imbalance are two of the central pathological features of common neurodegenerative diseases including Alzheimer, Parkinson, Huntington, and motor neuron diseases. How aggregation contributes to the pathogenic mechanisms of disease remains incompletely understood. Here, we integrate some of the key and emerging ideas as to how protein aggregation relates to imbalanced proteostasis with an emphasis on Huntington disease as our area of main expertise. We propose the term "aggregomics" be coined in reference to how aggregation of particular proteins concomitantly influences the spatial organization and protein-protein interactions of the surrounding proteome. Meta-analysis of aggregated interactomes from various published datasets reveals chaperones and RNA-binding proteins are common components across various disease contexts. We conclude with an examination of therapeutic avenues targeting proteostasis mechanisms.

Hyperhomocysteinemia-induced autophagy and apoptosis with downregulation of hairy enhancer of split 1/5 in cortical neurons in mice

It has been reported that hyperhomocysteinemia (HHcy) is associated with neurodegenerative and cardiovascular diseases. However, little is known about brain histomorphology, neuronal organelles, and hairy enhancer of split (hes) expression under HHcy. In this study, non-HHcy and HHcy induced by high-methionine diet in apolipoprotein E–deficient (Apo E^−/−) mice were comparatively investigated. The histomorphology, ultrastructure, autophagosomes, apoptosis, and expression of proteins, HES1, HES5 and P62, were designed to assess the effects of HHcy on brain. The results showed that compared to the non-HHcy mice, the HHcy group had an increase in autophagosomes, vacuolization in mitochondria, and neuron apoptosis; treatment with folate and vitamin B₁₂ reduced the extent of these lesions. However, the elementary histomorphology, the numbers of cortical neurons, and Nissl bodies had no significant difference between the HHcy and the non-HHcy groups or the group treated with folate and vitamin B₁₂. Immunohistochemistry and immunofluorescence demonstrated a decrease in HES1- or HES5-positive neurons in the HHcy group when compared to the non-HHcy groups, wild-type, and Apo E^−/− controls, or the HHcy mice with folate and vitamin B₁₂ supplement. Western blots showed that HHcy induced a decreased expression of HES1 and HES5, or P62, in which the expression of HES1 and P62 was elevated by treating with folate and vitamin B₁₂ supplement. These results suggest that HHcy-enhanced brain damage is associated with increased autophagy and neuronal apoptosis in Apo E^−/− mice, in which downregulation of hes1 and hes5 is involved.

Blood-Brain Barrier Driven Pharmacoresistance in Amyotrophic Lateral Sclerosis and Challenges for Effective Drug Therapies

The blood-brain barrier (BBB) is essential for proper neuronal function, homeostasis, and protection of the central nervous system (CNS) microenvironment from blood-borne pathogens and neurotoxins. The BBB is also an impediment for CNS penetration of drugs. In some neurologic conditions, such as epilepsy and brain tumors, overexpression of P-glycoprotein, an efflux transporter whose physiological function is to expel catabolites and xenobiotics from the CNS into the blood stream, has been reported. Recent studies reported that overexpression of P-glycoprotein and increase in its activity at the BBB drives a progressive resistance to CNS penetration and persistence of riluzole, the only drug approved thus far for treatment of amyotrophic lateral sclerosis (ALS), rapidly progressive and mostly fatal neurologic disease. This review will discuss the impact of transporter-mediated pharmacoresistance for ALS drug therapy and the potential therapeutic strategies to improve the outcome of ALS clinical trials and efficacy of current and future drug treatments.

Drugs in clinical development for the treatment of amyotrophic lateral sclerosis

INTRODUCTION

Amyotrophic Lateral Sclerosis (ALS) is a fatal motor neuron progressive disorder for which no treatment exists to date. However, there are other investigational drugs and therapies currently under clinical development may offer hope in the near future. Areas covered: We have reviewed all the ALS ongoing clinical trials (until November 2016) and collected in Clinicaltrials.gov or EudraCT. We have described them in a comprehensive way and have grouped them in the following sections: biomarkers, biological therapies, cell therapy, drug repurposing and new drugs. Expert opinion: Despite multiple obstacles that explain the absence of effective drugs for the treatment of ALS, joint efforts among patient's associations, public and private sectors have fueled innovative research in this field, resulting in several compounds that are in the late stages of clinical trials. Drug repositioning is also playing an important role, having achieved the approval of some orphan drug applications, in late phases of clinical development. Endaravone has been recently approved in Japan and is pending in USA.

Integrated molecular landscape of amyotrophic lateral sclerosis provides insights into disease etiology

Amyotrophic lateral sclerosis (ALS) is a severe, progressive and ultimately fatal motor neuron disease caused by a combination of genetic and environmental factors, but its underlying mechanisms are largely unknown. To gain insight into the etiology of ALS, we here conducted genetic network and literature analyses of the top-ranked findings from six genome-wide association studies of sporadic ALS (involving 3589 cases and 8577 controls) as well as genes implicated in ALS etiology through other evidence, including familial ALS candidate gene association studies. We integrated these findings into a molecular landscape of ALS that allowed the identification of three main processes that interact with each other and are crucial to maintain axonal functionality, especially of the long axons of motor neurons, i.e. (1) Rho-GTPase signaling; (2) signaling involving the three regulatory molecules estradiol, folate, and methionine; and (3) ribonucleoprotein granule functioning and axonal transport. Interestingly, estradiol signaling is functionally involved in all three cascades and as such an important mediator of the molecular ALS landscape. Furthermore, epidemiological findings together with an analysis of possible gender effects in our own cohort of sporadic ALS patients indicated that estradiol may be a protective factor, especially for bulbar-onset ALS. Taken together, our molecular landscape of ALS suggests that abnormalities within three interconnected molecular processes involved in the functioning and maintenance of motor neuron axons are important in the etiology of ALS. Moreover, estradiol appears to be an important modulator of the ALS landscape, providing important clues for the development of novel disease-modifying treatments.

Methylcobalamin prevents mutant superoxide dismutase-1-induced motor neuron death in vitro

Amyotrophic lateral sclerosis (ALS) is an incurable progressive neurodegenerative disorder that causes motor dysfunction. Treatments and drugs that slow progression of ALS have garnered great interest. In the present study, we show that the vitamin B12 analog methylcobalamin (MBL) effectively and dose dependently prevented embryonic stem cell-derived motor neuron death induced by cocultivation with astrocytes expressing mutant human superoxide dismutase-1 (G93A). Moreover, cotreatment of MBL with a conventional ALS drug, riluzole, further enhanced survival of motor neurons in this in-vitro ALS model. Our results show the potential use of MBL as a treatment for ALS and suggest a possible combination therapy strategy with other types of approved ALS drugs.

Amyotrophic Lateral Sclerosis, 2016: existing therapies and the ongoing search for neuroprotection

INTRODUCTION

Amyotrophic lateral sclerosis (ALS), one in a family of age-related neurodegenerative disorders, is marked by predominantly cryptogenic causes, partially elucidated pathophysiology, and elusive treatments. The challenges of ALS are illustrated by two decades of negative drug trials.

AREAS COVERED

In this article, we lay out the current understanding of disease genesis and physiology in relation to drug development in ALS, stressing important accomplishments and gaps in knowledge. We briefly consider clinical ALS, the ongoing search for biomarkers, and the latest in trial design, highlighting major recent and ongoing clinical trials; and we discuss, in a concluding section on future directions, the prion-protein hypothesis of neurodegeneration and what steps can be taken to end the drought that has characterized drug discovery in ALS.

EXPERT OPINION

Age-related neurodegenerative disorders are fast becoming major public health problems for the world's aging populations. Several agents offer promise in the near-term, but drug development is hampered by an interrelated cycle of obstacles surrounding etiological, physiological, and biomarkers discovery. It is time for the type of government-funded, public-supported offensive on neurodegenerative disease that has been effective in other fields.

Edaravone, a Free Radical Scavenger, Delayed Symptomatic and Pathological Progression of Motor Neuron Disease in the Wobbler Mouse

Edaravone, a free radical scavenger is used widely in Japanese patients with acute cerebral infarction. This antioxidant could have therapeutic potentials for other neurological diseases. Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that affects the upper and the lower motor neuron, leading to death within 3-5 years after onset. A phase III clinical trial of edaravone suggested no significant effects in ALS patients. However, recent 2nd double-blind trial has demonstrated therapeutic benefits of edaravone in definite patients diagnosed by revised El Escorial diagnostic criteria of ALS. Two previous studies showed that edaravone attenuated motor symptoms or motor neuron degeneration in mutant superoxide dismutase 1-transgenic mice or rats, animal models of familial ALS. Herein we examined whether this radical scavenger can retard progression of motor dysfunction and neuropathological changes in wobbler mice, sporadic ALS-like model. After diagnosis of the disease onset at the postnatal age of 3-4 weeks, wobbler mice received edaravone (1 or 10 mg/kg, n = 10/group) or vehicle (n = 10), daily for 4 weeks by intraperitoneal administration. Motor symptoms and neuropathological changes were compared among three groups. Higher dose (10 mg/kg) of edaravone treatment significantly attenuated muscle weakness and contracture in the forelimbs, and suppressed denervation atrophy in the biceps muscle and degeneration in the cervical motor neurons compared to vehicle. Previous and the present studies indicated neuroprotective effects of edaravone in three rodent ALS-like models. This drug seems to be worth performing the clinical trial in ALS patients in the United States of American and Europe, in addition to Japan.

Homocysteine aggravates ROS-induced depression of transmitter release from motor nerve terminals: potential mechanism of peripheral impairment in motor neuron diseases associated with hyperhomocysteinemia

Homocysteine (HCY) is a pro-inflammatory sulphur-containing redox active endogenous amino acid, which concentration increases in neurodegenerative disorders including amyotrophic lateral sclerosis (ALS). A widely held view suggests that HCY could contribute to neurodegeneration via promotion of oxidative stress. However, the action of HCY on motor nerve terminals has not been investigated so far. We previously reported that oxidative stress inhibited synaptic transmission at the neuromuscular junction, targeting primarily the motor nerve terminals. In the current study, we investigated the effect of HCY on oxidative stress-induced impairment of transmitter release at the mouse diaphragm muscle. The mild oxidant H2O2 decreased the intensity of spontaneous quantum release from nerve terminals (measured as the frequency of miniature endplate potentials, MEPPs) without changes in the amplitude of MEPPs, indicating a presynaptic effect. Pre-treatment with HCY for 2 h only slightly affected both amplitude and frequency of MEPPs but increased the inhibitory potency of H2O2 almost two fold. As HCY can activate certain subtypes of glutamate N-methyl D-aspartate (NMDA) receptors we tested the role of NMDA receptors in the sensitizing action of HCY. Remarkably, the selective blocker of NMDA receptors, AP-5 completely removed the sensitizing effect of HCY on the H2O2-induced presynaptic depressant effect. Thus, at the mammalian neuromuscular junction HCY largely increases the inhibitory effect of oxidative stress on transmitter release, via NMDA receptors activation. This combined effect of HCY and local oxidative stress can specifically contribute to the damage of presynaptic terminals in neurodegenerative motoneuron diseases, including ALS.