Beta-amyloid 42 accumulation in the lumbar spinal cord motor neurons of amyotrophic lateral sclerosis patients

Association of APOE genotype and cerebrospinal fluid Aβ and tau biomarkers with cognitive and motor phenotype in amyotrophic lateral sclerosis

OBJECTIVE

Little is known about amyotrophic lateral sclerosis (ALS)-nonspecific cognitive deficits - most notably memory disturbance - and their biological underpinnings. We investigated the associations of the Alzheimer's disease (AD) genetic risk factor APOE and cerebrospinal fluid (CSF) biomarkers Aβ and tau proteins with cognitive and motor phenotype in ALS.

METHODS

APOE haplotype was determined in 281 ALS patients; for 105 of these, CSF levels of Aβ42, Aβ40, total tau (T-tau), and phosphorylated tau (P-tau181) were quantified by chemiluminescence enzyme immunoassay (CLEIA). The Edinburgh Cognitive and Behavioural ALS Screen (ECAS) was employed to evaluate the neuropsychological phenotype.

RESULTS

APOE-E4 allele was associated with worse ECAS memory score (median, 14.0 in carriers vs. 16.0 in non-carriers) and lower CSF Aβ42 (-0.8 vs. 0.1, log-transformed values) and Aβ42/40 ratio (-0.1 vs. 0.3). Some 37.1% of ALS patients showed low Aβ42 levels, possibly reflecting cerebral Aβ deposition. While lower Aβ42/40 correlated with lower memory score (β = 0.20), Aβ42 positively correlated with both ALS-specific (β = 0.24) and ALS-nonspecific (β = 0.24) scores. Although Aβ42/40 negatively correlated with T-tau (β = -0.29) and P-tau181 (β = -0.33), we found an unexpected positive association of Aβ42 and Aβ40 with both tau proteins. Regarding motor phenotype, lower levels of Aβ species were associated with lower motor neuron (LMN) signs (Aβ40: β = 0.34; Aβ42: β = 0.22).

CONCLUSIONS

APOE haplotype and CSF Aβ biomarkers are associated with cognitive deficits in ALS and particularly with memory impairment. This might partly reflect AD-like pathophysiological processes, but additional ALS-specific mechanisms could be involved.

Amyloid-beta and tau protein beyond Alzheimer's disease

ABSTRACT

The aggregation of amyloid-beta peptide and tau protein dysregulation are implicated to play key roles in Alzheimer's disease pathogenesis and are considered the main pathological hallmarks of this devastating disease. Physiologically, these two proteins are produced and expressed within the normal human body. However, under pathological conditions, abnormal expression, post-translational modifications, conformational changes, and truncation can make these proteins prone to aggregation, triggering specific disease-related cascades. Recent studies have indicated associations between aberrant behavior of amyloid-beta and tau proteins and various neurological diseases, such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis, as well as retinal neurodegenerative diseases like Glaucoma and age-related macular degeneration. Additionally, these proteins have been linked to cardiovascular disease, cancer, traumatic brain injury, and diabetes, which are all leading causes of morbidity and mortality. In this comprehensive review, we provide an overview of the connections between amyloid-beta and tau proteins and a spectrum of disorders.

Mitochondrial and Nuclear DNA Variants in Amyotrophic Lateral Sclerosis: Enrichment in the Mitochondrial Control Region and Sirtuin Pathway Genes in Spinal Cord Tissue

Amyotrophic Lateral Sclerosis (ALS) is a progressive disease with prevalent mitochondrial dysfunctions affecting both upper and lower motor neurons in the motor cortex, brainstem, and spinal cord. Despite mitochondria having their own genome (mtDNA), in humans, most mitochondrial genes are encoded by the nuclear genome (nDNA). Our study aimed to simultaneously screen for nDNA and mtDNA genomes to assess for specific variant enrichment in ALS compared to control tissues. Here, we analysed whole exome (WES) and whole genome (WGS) sequencing data from spinal cord tissues, respectively, of 6 and 12 human donors. A total of 31,257 and 301,241 variants in nuclear-encoded mitochondrial genes were identified from WES and WGS, respectively, while mtDNA reads accounted for 73 and 332 variants. Despite technical differences, both datasets consistently revealed a specific enrichment of variants in the mitochondrial Control Region (CR) and in several of these genes directly associated with mitochondrial dynamics or with Sirtuin pathway genes within ALS tissues. Overall, our data support the hypothesis of a variant burden in specific genes, highlighting potential actionable targets for therapeutic interventions in ALS.

New Insights into Oxidative Stress and Inflammatory Response in Neurodegenerative Diseases

Oxidative stress (OS) and inflammation are two important and well-studied pathological hallmarks of neurodegenerative diseases (NDDs). Due to elevated oxygen consumption, the high presence of easily oxidizable polyunsaturated fatty acids and the weak antioxidant defenses, the brain is particularly vulnerable to oxidative injury. Uncertainty exists over whether these deficits contribute to the development of NDDs or are solely a consequence of neuronal degeneration. Furthermore, these two pathological hallmarks are linked, and it is known that OS can affect the inflammatory response. In this review, we will overview the last findings about these two pathways in the principal NDDs. Moreover, we will focus more in depth on amyotrophic lateral sclerosis (ALS) to understand how anti-inflammatory and antioxidants drugs have been used for the treatment of this still incurable motor neuron (MN) disease. Finally, we will analyze the principal past and actual clinical trials and the future perspectives in the study of these two pathological mechanisms.

Mitochondria: A Promising Convergent Target for the Treatment of Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease characterized by the progressive loss of motor neurons, for which current treatment options are limited. Recent studies have shed light on the role of mitochondria in ALS pathogenesis, making them an attractive therapeutic intervention target. This review contains a very comprehensive critical description of the involvement of mitochondria and mitochondria-mediated mechanisms in ALS. The review covers several key areas related to mitochondria in ALS, including impaired mitochondrial function, mitochondrial bioenergetics, reactive oxygen species, metabolic processes and energy metabolism, mitochondrial dynamics, turnover, autophagy and mitophagy, impaired mitochondrial transport, and apoptosis. This review also highlights preclinical and clinical studies that have investigated various mitochondria-targeted therapies for ALS treatment. These include strategies to improve mitochondrial function, such as the use of dichloroacetate, ketogenic and high-fat diets, acetyl-carnitine, and mitochondria-targeted antioxidants. Additionally, antiapoptotic agents, like the mPTP-targeting agents minocycline and rasagiline, are discussed. The paper aims to contribute to the identification of effective mitochondria-targeted therapies for ALS treatment by synthesizing the current understanding of the role of mitochondria in ALS pathogenesis and reviewing potential convergent therapeutic interventions. The complex interplay between mitochondria and the pathogenic mechanisms of ALS holds promise for the development of novel treatment strategies to combat this devastating disease.

Using Redox Proteomics to Gain New Insights into Neurodegenerative Disease and Protein Modification

Antioxidant defenses in biological systems ensure redox homeostasis, regulating baseline levels of reactive oxygen and nitrogen species (ROS and RNS). Oxidative stress (OS), characterized by a lack of antioxidant defenses or an elevation in ROS and RNS, may cause a modification of biomolecules, ROS being primarily absorbed by proteins. As a result of both genome and environment interactions, proteomics provides complete information about a cell's proteome, which changes continuously. Besides measuring protein expression levels, proteomics can also be used to identify protein modifications, localizations, the effects of added agents, and the interactions between proteins. Several oxidative processes are frequently used to modify proteins post-translationally, including carbonylation, oxidation of amino acid side chains, glycation, or lipid peroxidation, which produces highly reactive alkenals. Reactive alkenals, such as 4-hydroxy-2-nonenal, are added to cysteine (Cys), lysine (Lys), or histidine (His) residues by a Michael addition, and tyrosine (Tyr) residues are nitrated and Cys residues are nitrosylated by a Michael addition. Oxidative and nitrosative stress have been implicated in many neurodegenerative diseases as a result of oxidative damage to the brain, which may be especially vulnerable due to the large consumption of dioxygen. Therefore, the current methods applied for the detection, identification, and quantification in redox proteomics are of great interest. This review describes the main protein modifications classified as chemical reactions. Finally, we discuss the importance of redox proteomics to health and describe the analytical methods used in redox proteomics.

Echinometra lucunter molecules reduce Aβ42-induced neurotoxicity in SH-SY5Y neuron-like cells: effects on disaggregation and oxidative stress

Background

Echinometra lucunter is a sea urchin commonly found on America's rocky shores. Its coelomic fluid contains molecules used for defense and biological processes, which may have therapeutic potential for the treatment of amyloid-based neurodegenerative diseases, such as Alzheimer's, that currently have few drug options available.

Methods

In this study, we incubated E. lucunter coelomic fluid (ELCF) and fractions obtained by solid phase extraction in SH-SY5Y neuron-like cells to evaluate their effect on cell viability caused by the oligomerized amyloid peptide 42 (Aβ42o). Moreover, the Aβ42o was quantified after the incubation with ELCF fractions in the presence or not of cells, to evaluate if samples could cause amyloid peptide disaggregation. Antioxidant activity was determined in ELCF fractions, and cells were evaluated to check the oxidative stress after incubation with samples. The most relevant fraction was analyzed by mass spectrometry for identification of molecules.

Results

ELCF and certain fractions could prevent and treat the reduction of cell viability caused by Aβ42o in SH-SY5Y neuron-like cells. We found that one fraction (El50) reduced the oligomerized Aβ42 and the oxidative stress caused by the amyloid peptide through its antioxidant molecules, which in turn reduced cell death. Mass spectrometry analysis revealed that El50 comprises small molecules containing flavonoid antioxidants, such as phenylpyridazine and dihydroquercetin, and two peptides.

Conclusion

Our results suggest that sea urchin molecules may interact with Aβ42o and oxidative stress, preventing or treating neurotoxicity, which may be useful in treating dementia.

Protein Biomarkers Shared by Multiple Neurodegenerative Diseases Are Calmodulin-Binding Proteins Offering Novel and Potentially Universal Therapeutic Targets

Seven major neurodegenerative diseases and their variants share many overlapping biomarkers that are calmodulin-binding proteins: Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), frontotemporal lobar dementia (FTD), Huntington's disease (HD), Lewy body disease (LBD), multiple sclerosis (MS), and Parkinson's disease (PD). Calcium dysregulation is an early and persistent event in each of these diseases, with calmodulin serving as an initial and primary target of increased cytosolic calcium. Considering the central role of calcium dysregulation and its downstream impact on calcium signaling, calmodulin has gained interest as a major regulator of neurodegenerative events. Here, we show that calmodulin serves a critical role in neurodegenerative diseases via binding to and regulating an abundance of biomarkers, many of which are involved in multiple neurodegenerative diseases. Of special interest are the shared functions of calmodulin in the generation of protein biomarker aggregates in AD, HD, LBD, and PD, where calmodulin not only binds to amyloid beta, pTau, alpha-synuclein, and mutant huntingtin but also, via its regulation of transglutaminase 2, converts them into toxic protein aggregates. It is suggested that several calmodulin binding proteins could immediately serve as primary drug targets, while combinations of calmodulin binding proteins could provide simultaneous insight into the onset and progression of multiple neurodegenerative diseases.

Bilirubin and Redox Stress in Age-Related Brain Diseases

Cellular redox status has a crucial role in brain physiology, as well as in pathologic conditions. Physiologic senescence, by dysregulating cellular redox homeostasis and decreasing antioxidant defenses, enhances the central nervous system's susceptibility to diseases. The reduction of free radical accumulation through lifestyle changes, and the supplementation of antioxidants as a prophylactic and therapeutic approach to increase brain health, are strongly suggested. Bilirubin is a powerful endogenous antioxidant, with more and more recognized roles as a biomarker of disease resistance, a predictor of all-cause mortality, and a molecule that may promote health in adults. The alteration of the expression and activity of the enzymes involved in bilirubin production, as well as an altered blood bilirubin level, are often reported in neurologic conditions and neurodegenerative diseases (together denoted NCDs) in aging. These changes may predict or contribute both positively and negatively to the diseases. Understanding the role of bilirubin in the onset and progression of NCDs will be functional to consider the benefits vs. the drawbacks and to hypothesize the best strategies for its manipulation for therapeutic purposes.

Design, in silico and pharmacological evaluation of a peptide inhibitor of BACE-1

Introduction: Alzheimer's disease (AD) is the main type of dementia, caused by the accumulation of amyloid plaques, formed by amyloid peptides after being processed from amyloid precursor protein (APP) by γ- and ß-secretases (BACE-1). Although amyloid peptides have been well established for AD, they have been found in other neurodegenerative diseases, such as Parkinson's disease, Lewy body dementia, and amyotrophic lateral sclerosis. Inhibitors of BACE-1 have been searched and developed, but clinical trials failed due to lack of efficacy or toxicity. Nevertheless, it is still considered a good therapeutic target, as it was proven to remove amyloid peptides and improve memory. Methods: In this work, we designed a peptide based on a sequence obtained from the marine fish Merluccius productus and evaluated it by molecular docking to verify its binding to BACE-1, which was tested experimentally by enzymatic kinetics and cell culture assays. The peptide was injected in healthy mice to study its pharmacokinetics and toxicity. Results: We could obtain a new sequence in which the first N-terminal amino acids and the last one bound to the catalytic site of BACE-1 and showed high stability and hydrophobicity. The synthetic peptide showed a competitive inhibition of BACE-1 and Ki = 94 nM, and when injected in differentiated neurons, it could reduce Aβ42o production. In plasma, its half-life is ∼1 h, clearance is 0.0015 μg/L/h, and Vss is 0.0015 μg/L/h. The peptide was found in the spleen and liver 30 min after injection and reduced its level after that, when it was quantified in the kidneys, indicating its fast distribution and urinary excretion. Interestingly, the peptide was found in the brain 2 h after its administration. Histological analysis showed no morphological alteration in any organ, as well as the absence of inflammatory cells, indicating a lack of toxicity. Discussion: We obtained a new BACE-1 inhibitor peptide with fast distribution to the tissues, without accumulation in any organ, but found in the brain, with the possibility to reach its molecular target, BACE-1, contributing to the reduction in the amyloid peptide, which causes amyloid-linked neurodegenerative diseases.

APP in the Neuromuscular Junction for the Development of Sarcopenia and Alzheimer's Disease

Sarcopenia, an illness condition usually characterized by a loss of skeletal muscle mass and muscle strength or function, is often associated with neurodegenerative diseases, such as Alzheimer's disease (AD), a common type of dementia, leading to memory loss and other cognitive impairment. However, the underlying mechanisms for their associations and relationships are less well understood. The App, a Mendelian gene for early-onset AD, encodes amyloid precursor protein (APP), a transmembrane protein enriched at both the neuromuscular junction (NMJ) and synapses in the central nervous system (CNS). Here, in this review, we highlight APP and its family members' physiological functions and Swedish mutant APP (APP_swe)'s pathological roles in muscles and NMJ. Understanding APP's pathophysiological functions in muscles and NMJ is likely to uncover insights not only into neuromuscular diseases but also AD. We summarize key findings from the burgeoning literature, which may open new avenues to investigate the link between muscle cells and brain cells in the development and progression of AD and sarcopenia.

Discovery of Biomarkers for Amyotrophic Lateral Sclerosis from Human Cerebrospinal Fluid Using Mass-Spectrometry-Based Proteomics

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterized by the loss of upper and lower motor neurons, which eventually may lead to death. Critical to the mission of developing effective therapies for ALS is the discovery of biomarkers that can illuminate mechanisms of neurodegeneration and have diagnostic, prognostic, or pharmacodynamic value. Here, we merged unbiased discovery-based approaches and targeted quantitative comparative analyses to identify proteins that are altered in cerebrospinal fluid (CSF) from patients with ALS. Mass spectrometry (MS)-based proteomic approaches employing tandem mass tag (TMT) quantification methods from 40 CSF samples comprising 20 patients with ALS and 20 healthy control (HC) individuals identified 53 proteins that are differential between the two groups after CSF fractionation. Notably, these proteins included both previously identified ones, validating our approach, and novel ones that have the potential for expanding biomarker repertoire. The identified proteins were subsequently examined using parallel reaction monitoring (PRM) MS methods on 61 unfractionated CSF samples comprising 30 patients with ALS and 31 HC individuals. Fifteen proteins (APOB, APP, CAMK2A, CHI3L1, CHIT1, CLSTN3, ERAP2, FSTL4, GPNMB, JCHAIN, L1CAM, NPTX2, SERPINA1, SERPINA3, and UCHL1) showed significant differences between ALS and the control. Taken together, this study identified multiple novel proteins that are altered in ALS, providing the foundation for developing new biomarkers for ALS.

The paradigm of amyloid precursor protein in amyotrophic lateral sclerosis: The potential role of the 682YENPTY687 motif

Neurodegenerative diseases are characterized by the progressive decline of neuronal function in several brain areas, and are always associated with cognitive, psychiatric, or motor deficits due to the atrophy of certain neuronal populations. Most neurodegenerative diseases share common pathological mechanisms, such as neurotoxic protein misfolding, oxidative stress, and impairment of autophagy machinery. Amyotrophic lateral sclerosis (ALS) is one of the most common adult-onset motor neuron disorders worldwide. It is clinically characterized by the selective and progressive loss of motor neurons in the motor cortex, brain stem, and spinal cord, ultimately leading to muscle atrophy and rapidly progressive paralysis. Multiple recent studies have indicated that the amyloid precursor protein (APP) and its proteolytic fragments are not only drivers of Alzheimer's disease (AD) but also one of the earliest signatures in ALS, preceding or anticipating neuromuscular junction instability and denervation. Indeed, altered levels of APP peptides have been found in the brain, muscles, skin, and cerebrospinal fluid of ALS patients. In this short review, we discuss the nature and extent of research evidence on the role of APP peptides in ALS, focusing on the intracellular C-terminal peptide and its regulatory motif ₆₈₂YENPTY₆₈₇, with the overall aim of providing new frameworks and perspectives for intervention and identifying key questions for future investigations.

Molecular Investigations of Protein Aggregation in the Pathogenesis of Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating progressive neurodegenerative disorder characterized by selective loss of lower and upper motor neurons (MNs) in the brain and spinal cord, resulting in paralysis and eventually death due to respiratory insufficiency. Although the fundamental physiological mechanisms underlying ALS are not completely understood, the key neuropathological hallmarks of ALS pathology are the aggregation and accumulation of ubiquitinated protein inclusions within the cytoplasm of degenerating MNs. Herein, we discuss recent insights into the molecular mechanisms that lead to the accumulation of protein aggregates in ALS. This will contribute to a better understanding of the pathophysiology of the disease and may open novel avenues for the development of therapeutic strategies.

Amyotrophic Lateral Sclerosis Pathoetiology and Pathophysiology: Roles of Astrocytes, Gut Microbiome, and Muscle Interactions via the Mitochondrial Melatonergic Pathway, with Disruption by Glyphosate-Based Herbicides

The pathoetiology and pathophysiology of motor neuron loss in amyotrophic lateral sclerosis (ALS) are still to be determined, with only a small percentage of ALS patients having a known genetic risk factor. The article looks to integrate wider bodies of data on the biological underpinnings of ALS, highlighting the integrative role of alterations in the mitochondrial melatonergic pathways and systemic factors regulating this pathway across a number of crucial hubs in ALS pathophysiology, namely glia, gut, and the muscle/neuromuscular junction. It is proposed that suppression of the mitochondrial melatonergic pathway underpins changes in muscle brain-derived neurotrophic factor, and its melatonergic pathway mimic, N-acetylserotonin, leading to a lack of metabolic trophic support at the neuromuscular junction. The attenuation of the melatonergic pathway in astrocytes prevents activation of toll-like receptor agonists-induced pro-inflammatory transcription factors, NF-kB, and yin yang 1, from having a built-in limitation on inflammatory induction that arises from their synchronized induction of melatonin release. Such maintained astrocyte activation, coupled with heightened microglia reactivity, is an important driver of motor neuron susceptibility in ALS. Two important systemic factors, gut dysbiosis/permeability and pineal melatonin mediate many of their beneficial effects via their capacity to upregulate the mitochondrial melatonergic pathway in central and systemic cells. The mitochondrial melatonergic pathway may be seen as a core aspect of cellular function, with its suppression increasing reactive oxygen species (ROS), leading to ROS-induced microRNAs, thereby altering the patterning of genes induced. It is proposed that the increased occupational risk of ALS in farmers, gardeners, and sportsmen and women is intimately linked to exposure, whilst being physically active, to the widely used glyphosate-based herbicides. This has numerous research and treatment implications.

Redox profiles of amyotrophic lateral sclerosis lymphoblasts with or without known SOD1 mutations

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a fatal and rapidly progressing neurodegenerative disease that affects motor neurons. This disease is associated with oxidative stress especially in mutant superoxide dismutase 1 (mutSOD1) patients. However, less is known for the most prevalent sporadic ALS form, due to a lack of disease models. Here, we studied oxidative stress profiles in lymphoblasts from ALS patients with mutSOD1 or unknown (undSOD1) mutations.

METHODS

mutSOD1 and undSOD1 lymphoblasts, as well as sex/age-matched controls (3/group) were obtained from Coriell and divided into 46 years-old-men (C1), 46 years-old-women (C2) or 26/27 years-old-men (C3) cohorts. Growth curves were performed, and several parameters associated with redox homeostasis were evaluated, including SOD activity and expression, general oxidative stress levels, lipid peroxidation, response to oxidative stimulus, glutathione redox cycle, catalase expression, and activity, and Nrf2 transcripts. Pooled (all cohorts) and paired (intra-cohort) statistical analyses were performed, followed by clustering and principal component analyses (PCA).

RESULTS

Although a high heterogeneity among lymphoblast redox profiles was found between cohorts, clustering analysis based on 7 parameters with high chi-square ranking (total SOD activity, oxidative stress levels, catalase transcripts, SOD1 protein levels, metabolic response to mM concentrations of tert-butyl hydroperoxide, glutathione reductase activity, and Nrf2 transcript levels) provided a perfect cluster segregation between samples from healthy controls and ALS (undSOD1 and mutSOD1), also visualized in the PCA.

CONCLUSIONS

Our results show distinct redox signatures in lymphoblasts from mutSOD1, undSOD1 and healthy controls that can be used as therapeutic targets for ALS drug development.

Age Related Changes in Muscle Mass and Force Generation in the Triple Transgenic (3xTgAD) Mouse Model of Alzheimer's Disease

Emerging evidence suggests that patients with Alzheimer's disease (AD) may show accelerated sarcopenia phenotypes. To investigate whether pathological changes associated with neuronal death and cognitive dysfunction also occur in peripheral motor neurons and muscle as a function of age, we used the triple transgenic mouse model of AD (3xTgAD mice) that carries transgenes for mutant forms of APP, Tau, and presenilin proteins that are associated with AD pathology. We measured changes in motor neurons and skeletal muscle function and metabolism in young (2 to 4 month) female control and 3xTgAD mice and in older (18-20 month) control and 3xTgAD female mice. In older 3xTgAD mice, we observed a number of sarcopenia-related phenotypes, including significantly fragmented and denervated neuromuscular junctions (NMJs) associated with a 17% reduction in sciatic nerve induced vs. direct muscle stimulation induced contractile force production, and a 30% decrease in gastrocnemius muscle mass. On the contrary, none of these outcomes were found in young 3xTgAD mice. We also measured an accumulation of amyloid-β (Aβ) in both skeletal muscle and neuronal tissue in old 3xTgAD mice that may potentially contribute to muscle atrophy and NMJ disruption in the older 3xTgAD mice. Furthermore, the TGF-β mediated atrophy signaling pathway is activated in old 3xTgAD mice and is a potential contributing factor in the muscle atrophy that occurs in this group. Perhaps surprisingly, mitochondrial oxygen consumption and reactive oxygen species (ROS) production are not elevated in skeletal muscle from old 3xTgAD mice. Together, these results provide new insights into the effect of AD pathological mechanisms on peripheral changes in skeletal muscle.

The Potential Role of Peripheral Oxidative Stress on the Neurovascular Unit in Amyotrophic Lateral Sclerosis Pathogenesis: A Preliminary Report from Human and In Vitro Evaluations

Oxidative stress, the alteration of mitochondrial function, and changes in the neurovascular unit (NVU) could play a role in Amyotrophic Lateral Sclerosis (ALS) pathogenesis. Our aim was to analyze the plasma redox system and nitric oxide (NO) in 25 ALS new-diagnosed patients and five healthy controls and the effects of plasma on the peroxidation/mitochondrial function in human umbilical cord-derived endothelial vascular cells (HUVEC) and astrocytes. In plasma, thiobarbituric acid reactive substances (TBARS), glutathione (GSH), and nitric oxide (NO) were analyzed by using specific assays. In HUVEC/astrocytes, the effects of plasma on the release of mitochondrial reactive oxygen species (mitoROS) and NO, viability, and mitochondrial membrane potential were investigated. In the plasma of ALS patients, an increase in TBARS and a reduction in GSH and NO were found. In HUVEC/astrocytes treated with a plasma of ALS patients, mitoROS increased, whereas cell viability and mitochondrial membrane potential decreased. Our results show that oxidative stress and NVU play a central role in ALS and suggest that unknown plasma factors could be involved in the disease pathogenesis. Quantifiable changes in ALS plasma related to redox state alterations can possibly be used for early diagnosis.

αS Oligomers Generated from Interactions with a Polyunsaturated Fatty Acid and a Dopamine Metabolite Differentially Interact with Aβ to Enhance Neurotoxicity

It is increasingly becoming clear that neurodegenerative diseases are not as discrete as originally thought to be but display significant overlap in histopathological and clinical presentations. For example, nearly half of the patients with Alzheimer's disease (AD) and synucleinopathies such as Parkinson's disease (PD) show symptoms and pathological features of one another. Yet, the molecular events and features that underlie such comorbidities in neurodegenerative diseases remain poorly understood. Here, inspired to uncover the molecular underpinnings of the overlap between AD and PD, we investigated the interactions between amyloid-β (Aβ) and α-synuclein (αS), aggregates of which form the major components of amyloid plaques and Lewy bodies, respectively. Specifically, we focused on αS oligomers generated from the dopamine metabolite called dihydroxyphenylacetaldehyde (DOPAL) and a polyunsaturated fatty acid docosahexaenoic acid (DHA). The two αS oligomers showed structural and conformational differences as confirmed by the disparity in size, secondary structure, susceptibility to proteinase K digestion, and cytotoxicity. More importantly, the two oligomers differentially modulated Aβ aggregation; while both inhibited Aβ aggregation to varying extents, they also induced structurally different Aβ assemblies. Furthermore, Aβ seeded with DHA-derived αS oligomers showed greater toxicity than DOPAL-derived αS oligomers in SH-SY5Y neuroblastoma cells. These results provide insights into the interactions between two amyloid proteins with empirically distinctive biophysical and cellular manifestations, enunciating a basis for potentially ubiquitous cross-amyloid interactions across many neurodegenerative diseases.

The Air We Breathe: Air Pollution as a Prevalent Proinflammatory Stimulus Contributing to Neurodegeneration

Air pollution is regarded as an important risk factor for many diseases that affect a large proportion of the human population. To date, accumulating reports have noted that particulate matter (PM) is closely associated with the course of cardiopulmonary disorders. As the incidence of Alzheimer’s disease (AD), Parkinson’s disease (PD), and autoimmune disorders have risen and as the world’s population is aging, there is an increasing interest in environmental health hazards, mainly air pollution, which has been slightly overlooked as one of many plausible detrimental stimuli contributing to neurodegenerative disease onset and progression. Epidemiological studies have indicated a noticeable association between exposure to PM and neurotoxicity, which has been gradually confirmed by in vivo and in vitro studies. After entering the body directly through the olfactory epithelium or indirectly by passing through the respiratory system into the circulatory system, air pollutants are subsequently able to reach the brain. Among the potential mechanisms underlying particle-induced detrimental effects in the periphery and the central nervous system (CNS), increased oxidative stress, inflammation, mitochondrial dysfunction, microglial activation, disturbance of protein homeostasis, and ultimately, neuronal death are often postulated and concomitantly coincide with the main pathomechanisms of neurodegenerative processes. Other complementary mechanisms by which PM could mediate neurotoxicity and contribute to neurodegeneration remain unconfirmed. Furthermore, the question of how strong and proven air pollutants are as substantial adverse factors for neurodegenerative disease etiologies remains unsolved. This review highlights research advances regarding the issue of PM with an emphasis on neurodegeneration markers, symptoms, and mechanisms by which air pollutants could mediate damage in the CNS. Poor air quality and insufficient knowledge regarding its toxicity justify conducting scientific investigations to understand the biological impact of PM in the context of various types of neurodegeneration.

A Synthetic SOD/Catalase Mimic Compound for the Treatment of ALS

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease affecting motor neurons. To date, the etiology of the disease is still unclear, with evidence of reactive oxygen species, mitochondrial dysfunction, iron homeostasis perturbation, protein misfolding and protein aggregation as key players in the pathology of the disease. Twenty percent of familial ALS and two percent of sporadic ALS instances are due to a mutation in Cu/Zn superoxide dismutase (SOD1). Sporadic and familial ALS affects the same neurons with similar pathology; therefore, the underlying hypothesis is that therapies effective in mutant SOD1 models could be translated to sporadic ALS. Corrole metal complexes have lately been identified as strong and potent catalytic antioxidants with beneficial effects in oxidative stress-related diseases such as Parkinson's disease, Alzheimer's disease, atherosclerosis, diabetes and its complications. One of the most promising candidates is the iron complex of an amphiphilic corrole, 1-Fe. In this study we used the SOD1 G93R mutant zebrafish ALS model to assess whether 1-Fe, as a potent catalytic antioxidant, displays any therapeutic merits in vivo. Our results show that 1-Fe caused a substantial increase in mutant zebrafish locomotor activity (up to 30%), bringing the locomotive abilities of the mutant treated group close to that of the wild type untreated group (50% more than the mutated untreated group). Furthermore, 1-Fe did not affect WT larvae locomotor activity, suggesting that 1-Fe enhances locomotor ability by targeting mechanisms underlying SOD1 ALS specifically. These results may pave the way for future development of 1-Fe as a viable treatment for ALS.

Prognostic Role of CSF β-amyloid 1-42/1-40 Ratio in Patients Affected by Amyotrophic Lateral Sclerosis

The involvement of β-amyloid (Aβ) in the pathogenesis of amyotrophic lateral sclerosis (ALS) has been widely discussed and its role in the disease is still a matter of debate. Aβ accumulates in the cortex and the anterior horn neurons of ALS patients and seems to affect their survival. To clarify the role of cerebrospinal fluid (CSF) Aβ 1–42 and Aβ 42/40 ratios as a potential prognostic biomarker for ALS, we performed a retrospective observational study on a cohort of ALS patients who underwent a lumbar puncture at the time of the diagnosis. CSF Aβ 1–40 and Aβ 1–42 ratios were detected by chemiluminescence immunoassay and their values were correlated with clinical features. We found a significant correlation of the Aβ 42/40 ratio with age at onset and Mini Mental State Examination (MMSE) scores. No significant correlation of Aβ 1–42 or Aβ 42/40 ratios to the rate of progression of the disease were found. Furthermore, when we stratified patients according to Aβ 1–42 concentration and the Aβ 42/40 ratio, we found that patients with a lower Aβ 42/40 ratio showed a shorter survival. Our results support the hypothesis that Aβ 1–42 could be involved in some pathogenic mechanism of ALS and we suggest the Aβ 42/40 ratio as a potential prognostic biomarker.

Oxidative Stress in Amyotrophic Lateral Sclerosis: Pathophysiology and Opportunities for Pharmacological Intervention

Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease or Charcot disease, is a fatal neurodegenerative disease that affects motor neurons (MNs) and leads to death within 2–5 years of diagnosis, without any effective therapy available. Although the pathological mechanisms leading to ALS are still unknown, a wealth of evidence indicates that an excessive reactive oxygen species (ROS) production associated with an inefficient antioxidant defense represents an important pathological feature in ALS. Substantial evidence indicates that oxidative stress (OS) is implicated in the loss of MNs and in mitochondrial dysfunction, contributing decisively to neurodegeneration in ALS. Although the modulation of OS represents a promising approach to protect MNs from degeneration, the fact that several antioxidants with beneficial effects in animal models failed to show any therapeutic benefit in patients raises several questions that should be analyzed. Using specific queries for literature search on PubMed, we review here the role of OS-related mechanisms in ALS, including the involvement of altered mitochondrial function with repercussions in neurodegeneration. We also describe antioxidant compounds that have been mostly tested in preclinical and clinical trials of ALS, also describing their respective mechanisms of action. While the description of OS mechanism in the different mutations identified in ALS has as principal objective to clarify the contribution of OS in ALS, the description of positive and negative outcomes for each antioxidant is aimed at paving the way for novel opportunities for intervention. In conclusion, although antioxidant strategies represent a very promising approach to slow the progression of the disease, it is of utmost need to invest on the characterization of OS profiles representative of each subtype of patient, in order to develop personalized therapies, allowing to understand the characteristics of antioxidants that have beneficial effects on different subtypes of patients.

Proton pump inhibitors act with unprecedented potencies as inhibitors of the acetylcholine biosynthesizing enzyme-A plausible missing link for their association with incidence of dementia

INTRODUCTION

Several pharmacoepidemiological studies indicate that proton pump inhibitors (PPIs) significantly increase the risk of dementia. Yet, the underlying mechanism is not known. Here, we report the discovery of an unprecedented mode of action of PPIs that explains how PPIs may increase the risk of dementia.

METHODS

Advanced in silico docking analyses and detailed enzymological assessments were performed on PPIs against the core-cholinergic enzyme, choline-acetyltransferase (ChAT), responsible for biosynthesis of acetylcholine (ACh).

RESULTS

This report shows compelling evidence that PPIs act as inhibitors of ChAT, with high selectivity and unprecedented potencies that lie far below their in vivo plasma and brain concentrations.

DISCUSSION

Given that accumulating evidence points at cholinergic dysfunction as a driving force of major dementia disorders, our findings mechanistically explain how prolonged use of PPIs may increase incidence of dementia. This call for restrictions for prolonged use of PPIs in elderly, and in patients with dementia or amyotrophic lateral sclerosis.

Aβ1-42 and Tau as Potential Biomarkers for Diagnosis and Prognosis of Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is the most common motor neuron disease, but its definitive diagnosis delays around 12 months. Although the research is highly active in the biomarker field, the absence of specific biomarkers for diagnosis contributes to this long delay. Another strategy of biomarker identification based on less specific but sensitive molecules may be of interest in clinical practice. For example, markers related to other neurodegenerative diseases such as Alzheimer's disease (AD) could be fully explored. Here, we compared baseline levels of amyloidβ1-42 (Aβ1-42), total Tau, and phosphorylated-Tau (phospho-Tau) protein in the cerebrospinal fluid (CSF) of ALS patients to controls and correlated it with clinical parameters of ALS progression collected over 12 months. We observed increased levels of Aβ1-42 (controls: 992.9 ± 358.3 ng/L; ALS: 1277.0 ± 296.6 ng/L; p < 0.0001) and increased Aβ1-42/phospho-Tau ratio and Innotest Amyloid Tau Index (IATI) (both p < 0.0001). IATI and the phospho-Tau/total Tau ratio correlated positively with ALSFRS-R and weight at baseline. Multivariate analysis revealed that baseline ALSFRS-R was associated with Aβ1-42 and phospho-Tau/total Tau ratio (p = 0.0109 and p = 0.0013, respectively). Total Tau and phospho-Tau levels correlated negatively with ALSFRS-R variation at months 6 and 9, respectively (p = 0.02 and p = 0.04, respectively). Phospho-Tau/total Tau ratio correlated positively with ALSFRS-R variation at month 9 (p = 0.04). CSF levels of Aβ1-42 could be used as a complementary tool to ALS diagnosis, and total Tau and phospho-Tau levels may help establishing the prognosis of ALS. Further studies merit exploring the pathophysiological mechanisms associated with these markers. Despite their lack of specificity, phospho-Tau/total Tau and Aβ1-42 should be combined to other biological and clinical markers in order to improve ALS management.

Exploration of attractor modules for sporadic amyotrophic lateral sclerosis via systemic module inference and attract method

Sporadic amyotrophic lateral sclerosis (SALS) is a devastating neurodegenerative disorder. However, the understanding of SALS is still poor. This research aimed to excavate attractor modules for SALS by integrating the systemic module inference and attract method. To achieve this, gene expression data and protein-protein data were recruited and preprocessed. Then, based on the Spearman's correlation coefficient (SCC) of the interactions under these two conditions, two PPI networks separately with 870 nodes (979 interactions) in normal control group and 601 nodes (777 interactions) in SALS group were built. Systemic module inference method was performed to identify the modules, and attract method was used to identify attractor modules. Finally, pathway enrichment analysis was performed to disclose the functional enrichment of these attractor modules. In total 44 and 118 modules were identified for normal control and SALS groups, respectively. Among them, 6 modules were with similar gene composition between the two groups, and all 6 modules were considered as the attractor module via attract method. These attractor modules might be potential biomarkers for early diagnosis and therapy of SALS, which could provide insight into the disease biology and suggest possible directions for drug screening programs.

Protective role of phenylethanoid glycosides, Torenoside B and Savatiside A, in Alzheimer's disease

The current study assessed the efficacy of two phenylethanoid glycosides (PhGs), Torenoside B (TB) and Savatiside A (SA), in the treatment of Alzheimer's disease (AD). The effects of TB and SA compounds were first assessed following amyloid beta (Aβ)_25-35 induction in SH-SY5Y cells at a range of concentrations. Their effects on cell viability and reactive oxygen species (ROS) were determined by performing MTT and dichlorofluorescin diacetate assays, respectively. The concentration of intracellular Ca²⁺ was determined using Fluo-3AM to stain SH-SY5Y cells. SA and TB treatments were also assessed in Aβ_25-35-induced mice. Y-maze and Morris water maze methods were utilized to assess murine learning and memory capability. The pathological changes of murine hippocampi was determined using H&E and Nissl staining. In addition, biochemical parameters associated with intracellular reactive oxygen pathways including Maleic dialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), acetylcholinesterase (AChE) and Calnexin were also assessed. TB and SA treatment in Aβ_25-35-induced SH-SY5Y cells resulted in the restoration of cell morphology, an increase of SOD and GSH-Px activity, a decrease in ROS, Ca²⁺ and MDA content, and a decrease in Calnexin expression. Furthermore, SA or TB treatment administered to Aβ_25-35-induced mice improved their spatial/non-spatial learning and memory capabilities. The efficacy of treatment was also supported by a marked change in the morphological structure of pyramidal neurons in the CA1 areas of murine hippocampi, as well as an increase of SOD and GSH-Px activity. Treatment also resulted in a decrease in MDA content, AchE activity and Calnexin expression in murine hippocampal tissue. As potential AD treatment drugs, SA and TB compounds have been demonstrated to alleviate the oxidative stress induced by Aβ_25-35 via the regulation of intracellular calcium homeostasis and Calnexin, preventing AD development.

Mitochondrial Targeting in Neurodegeneration: A Heme Perspective

Mitochondrial dysfunction has achieved an increasing interest in the field of neurodegeneration as a pathological hallmark for different disorders. The impact of mitochondria is related to a variety of mechanisms and several of them can co-exist in the same disease. The central role of mitochondria in neurodegenerative disorders has stimulated studies intended to implement therapeutic protocols based on the targeting of the distinct mitochondrial processes. The review summarizes the most relevant mechanisms by which mitochondria contribute to neurodegeneration, encompassing therapeutic approaches. Moreover, a new perspective is proposed based on the heme impact on neurodegeneration. The heme metabolism plays a central role in mitochondrial functions, and several evidences indicate that alterations of the heme metabolism are associated with neurodegenerative disorders. By reporting the body of knowledge on this topic, the review intends to stimulate future studies on the role of heme metabolism in neurodegeneration, envisioning innovative strategies in the struggle against neurodegenerative diseases.

Immununochemical Markers of the Amyloid Cascade in the Hippocampus in Motor Neuron Diseases

BACKGROUND

Several findings suggest that the amyloid precursor protein (APP) and the amyloid cascade may play a role in motor neuron disease (MND).

OBJECTIVE

Considering that dementia is one of the most frequent non-motor symptoms in amyotrophic lateral sclerosis (ALS) and that hippocampus is one of the brain areas with greater presence of amyloid-related changes in neurodegenerative diseases, our aim was to analyze the molecular markers of the amyloid cascade of APP in pathology studies of the hippocampus of autopsied patients with ALS and ALS-frontotemporal dementia (FTD).

METHODS

We included nine patients with MND and four controls. Immunohistochemical studies and confocal microscopy were used to analyze the expression of APP, TDP-43, pho-TDP-43, Aβ, APP intracellular cytoplasmatic domain (AICD) peptide, Fe65 protein, and pho-TAU in the hippocampus of seven patients with ALS, two patients with ALS-FTD, and four controls. These findings were correlated with clinical data.

RESULTS

Patients displayed increased expression of APP and Aβ peptide. The latter was correlated with cytoplasmic pho-TDP-43 expression. We also found decreased Fe65 expression. A parallel increase in AICD expression was not found. Patients showed increased expression of pho-TAU in the hippocampus. Findings were similar in patients with ALS and those with ALS-FTD, though more marked in the latter group.

CONCLUSION

Post-mortem analyses showed that the amyloid cascade is activated in the hippocampus of patients with MND and correlated with cytoplasmic pho-TDP-43 expression. The number of intracellular or extracellular aggregates of Aβ peptides was not significant.

Neurodegenerative and neurological disorders by small inhaled particles

The world's population is steadily ageing and as a result, health conditions related to ageing, such as dementia, have become a major public health concern. In 2001, it was estimated that there were almost 5 million Europeans suffering from Alzheimer's disease (AD) and this figure has been projected to almost double by 2040. About 40% of people over 85 suffer from AD, and another 10% from Parkinson's disease (PD). The majority of AD and PD cases are of sporadic origin and environmental factors play an important role in the aetiology. Epidemiological research identified airborne particulate matter (PM) as one of the environmental factors potentially involved in AD and PD pathogenesis. Also, cumulating evidence demonstrates that the smallest sizes of the inhalable fraction of ambient particulate matter, also referred to as ultrafine particulate matter or nano-sized particles, are capable of inducing effects beyond the respiratory system. Translocation of very small particles via the olfactory epithelium in the nose or via uptake into the circulation has been demonstrated through experimental rodent studies with engineered nanoparticles. Outdoor air pollution has been linked to several health effects including oxidative stress and neuroinflammation that may ultimately result in neurodegeneration and cognitive impairment. This review aims to evaluate the relationship between exposure to inhaled ambient particles and neurodegeneration.

The Ubiquitin-Proteasome System: Potential Therapeutic Targets for Alzheimer's Disease and Spinal Cord Injury

The ubiquitin-proteasome system (UPS) is a crucial protein degradation system in eukaryotes. Herein, we will review advances in the understanding of the role of several proteins of the UPS in Alzheimer’s disease (AD) and functional recovery after spinal cord injury (SCI). The UPS consists of many factors that include E3 ubiquitin ligases, ubiquitin hydrolases, ubiquitin and ubiquitin-like molecules, and the proteasome itself. An extensive body of work links UPS dysfunction with AD pathogenesis and progression. More recently, the UPS has been shown to have vital roles in recovery of function after SCI. The ubiquitin hydrolase (Uch-L1) has been proposed to increase cellular levels of mono-ubiquitin and hence to increase rates of protein turnover by the UPS. A low Uch-L1 level has been linked with Aβ accumulation in AD and reduced neuroregeneration after SCI. One likely mechanism for these beneficial effects of Uch-L1 is reduced turnover of the PKA regulatory subunit and consequently, reduced signaling via CREB. The neuron-specific F-box protein Fbx2 ubiquitinates β-secretase thus targeting it for proteasomal degradation and reducing generation of Aβ. Both Uch-L1 and Fbx2 improve synaptic plasticity and cognitive function in mouse AD models. The role of Fbx2 after SCI has not been examined, but abolishing ß-secretase reduces neuronal recovery after SCI, associated with reduced myelination. UBB+1, which arises through a frame-shift mutation in the ubiquitin gene that adds 19 amino acids to the C-terminus of ubiquitin, inhibits proteasomal function and is associated with increased neurofibrillary tangles in patients with AD, Pick’s disease and Down’s syndrome. These advances in understanding of the roles of the UPS in AD and SCI raise new questions but, also, identify attractive and exciting targets for potential, future therapeutic interventions.

Differential roles of Aβ processing in hypoxia-induced axonal damage

Axonopathy is a common and early phase in neurodegenerative and traumatic CNS diseases. Recent work suggests that amyloid β (Aβ) produced from amyloid precursor protein (APP) may be a critical downstream mediator of CNS axonopathy in CNS diseases, particularly those associated with hypoxia. We critically tested this hypothesis in an adult retinal explant system that preserves the three-dimensional organization of the retina while permitting direct imaging of two cardinal features of early-stage axonopathy: axonal structural integrity and axonal transport capacity. Using this system, we found via pharmacological inhibition and genetic deletion of APP that production of Aβ is a necessary step in structural compromise of retinal ganglion cell (RGC) axons induced by the disease-relevant stressor hypoxia. However, identical blockade of Aβ production was not sufficient to protect axons from associated hypoxia-induced reduction in axonal transport. Thus, Aβ mediates distinct facets of hypoxia-induced axonopathy and may represent a functionally selective pharmacological target for therapies directed against early-stage axonopathy in CNS diseases.

Amyotrophic lateral sclerosis as a spatiotemporal mislocalization disease: location, location, location

Spatiotemporal localization of signals is a fundamental feature impacting cell survival and proper function. The cell needs to respond in an accurate manner in both space and time to both intra- and intercellular environment cues. The regulation of this comprehensive process involves the cytoskeleton and the trafficking machinery, as well as local protein synthesis and ligand-receptor mechanisms. Alterations in such mechanisms can lead to cell dysfunction and disease. Motor neurons that can extend over tens of centimeters are a classic example for the importance of such events. Changes in spatiotemporal localization mechanisms are thought to play a role in motor neuron degeneration that occurs in amyotrophic lateral sclerosis (ALS). In this review we will discuss these mechanisms and argue that possible misregulated factors can lead to motor neuron degeneration in ALS.

Effective suppression of nitric oxide production by HX106N through transcriptional control of heme oxygenase-1

Heme oxygenase-1 (HO-1) has been suggested to be a key neuroprotective enzyme because of its widespread distribution in the brain as well as its strong antioxidative effects. HX106N, a water-soluble botanical formulation, has previously been demonstrated to prevent amyloid β-induced memory impairment and oxidative stress in mice by upregulating HO-1 levels. In this study, the underlying molecular mechanisms of HX106N-induced HO-1 expression were investigated using BV-2 cells, a murine microglial cell line, and primary microglia. Treatment with HX106N induced the expression of HO-1 at the transcriptional level through the stress-responsive element-containing enhancer present in the ho-1 promoter. Nuclear factor E2-related factor 2 (Nrf2) was activated in cells treated with HX106N. The results from knockdown assay showed that small interfering RNA of Nrf2 attenuated HX106N-mediated HO-1 expression. Pharmacological inhibitors of p38 and JNK mitogen-activated protein kinases suppressed the HX106N-mediated induction of HO-1. The NF-κB signaling pathway was activated by HX106N and played a role in HX106N-induced HO-1 expression. Furthermore, HO-1 and one of its by-products during the enzymatic degradation of heme, CO, were found to be involved in HX106N-mediated suppression of NO production. Taken together, these data indicate that HX106N exerts potent antioxidative effects by increasing the expression of HO-1 through multiple signaling pathways, leading to the suppression of NO production.

Glutamate protects neuromuscular junctions from deleterious effects of β-amyloid peptide and conversely: an in vitro study in a nerve-muscle coculture

Murine models of Alzheimer's disease with elevated levels of amyloid-β (Aβ) peptide present motor axon defects and neuronal death. Aβ1-42 accumulation is observed in motor neurons and spinal cords of sporadic and familial cases of amyotrophic lateral sclerosis (ALS). Motor neurons are highly susceptible to glutamate, which has a role in ALS neuronal degeneration. The current study investigates the link between Aβ and glutamate in this neurodegenerative process. Primary rat nerve and human muscle cocultures were intoxicated with glutamate or Aβ. Neuromuscular junction (NMJ) mean size and neurite length were evaluated. The role of N-methyl-D-aspartate receptor (NMDAR) was investigated by using MK801. Glutamate and Aβ production were evaluated in culture supernatant. The current study shows that NMJs are highly sensitive to Aβ peptide, that the toxic pathway involves glutamate and NMDAR, and that glutamate and Aβ act in an interlinked manner. Some motor diseases (e.g., ALS), therefore, could be considered from a new point of view related to these balance disturbances.

Multicentre quality control evaluation of different biomarker candidates for amyotrophic lateral sclerosis

Abstract Amyotrophic lateral sclerosis (ALS) is a progressive motor neuron disease that mainly causes degeneration of the upper and lower motor neurons, ultimately leading to paralysis and death within three to five years after first symptoms. The pathological mechanisms leading to ALS are still not completely understood. Several biomarker candidates have been proposed in cerebrospinal fluid (CSF). However, none of these has successfully translated into clinical routine. Part of the reason for this failure to translate may relate to differences across laboratories. For this reason, several of the most commonly used ALS biomarker candidates were evaluated on clinically well-defined ALS samples from six European centres in a multicentre sample-collection approach with centralized sample processing. Results showed that phosphorylated neurofilament heavy chain differentiated between ALS and control cases in all centres. We therefore propose that measurement of phosphorylated neurofilaments in CSF is the most promising candidate for translation into the clinical setting and might serve as a benchmark for other biomarker candidates.

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.

Barriers to novel therapeutics in amyotrophic lateral sclerosis

SUMMARY Amyotrophic lateral sclerosis is a devastating neurodegenerative condition primarily involving the motor system in the cerebral cortex, brain stem and spinal cord, but can, in later disease stages, also affect distinct extramotor brain regions. In this article, we discuss the prevalent barriers, including clinical and genetic variability of amyotrophic lateral sclerosis, frailty of the current mouse model and inadequateness of clinical trials, in the search for novel therapeutics. Approaches in terms of understanding the pathogenesis, and the search for biomarkers to initiate early or even presymptomatic treatment and monitor treatment effects are highlighted.

A neurodegeneration-specific gene-expression signature of acutely isolated microglia from an amyotrophic lateral sclerosis mouse model

Microglia are resident immune cells of the CNS that are activated by infection, neuronal injury, and inflammation. Here, we utilize flow cytometry and deep RNA sequencing of acutely isolated spinal cord microglia to define their activation in vivo. Analysis of resting microglia identified 29 genes that distinguish microglia from other CNS cells and peripheral macrophages/monocytes. We then analyzed molecular changes in microglia during neurodegenerative disease activation using the SOD1(G93A) mouse model of amyotrophic lateral sclerosis (ALS). We found that SOD1(G93A) microglia are not derived from infiltrating monocytes, and that both potentially neuroprotective and toxic factors, including Alzheimer's disease genes, are concurrently upregulated. Mutant microglia differed from SOD1(WT), lipopolysaccharide-activated microglia, and M1/M2 macrophages, defining an ALS-specific phenotype. Concurrent messenger RNA/fluorescence-activated cell sorting analysis revealed posttranscriptional regulation of microglia surface receptors and T cell-associated changes in the transcriptome. These results provide insights into microglia biology and establish a resource for future studies of neuroinflammation.

Inhibition of amyloid precursor protein beta-secretase cleavage site affects survival and motor functions of amyotrophic lateral sclerosis transgenic mice

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease defined by motor neuron loss. Recent studies have reported an increase in amyloid precursor protein (APP) levels and in its cleavage products in ALS patients indicating their possible involvement in this disease. APP is a transmembrane protein processed either by β-secretase or α-secretase followed by γ-secretase. The APP cleavage products--soluble APP-β (sAPPβ), amyloidogenic Aβ, and amino-terminal fragment N-APP--mediate a reduction in synaptic transmission, synaptic loss, neurite retraction and, ultimately, programmed cell death.

OBJECTIVE

To elucidate the role of APP cleavage products in the pathology of ALS.

METHODS

ALS mouse models that express mutant superoxide dismutase 1 were treated intraventricularly with a monoclonal antibody that blocks the β-secretase cleavage site on APP. Levels of the APP cleavage product called sAPPβ, motor functions and survival were assessed.

RESULTS

Inhibition of APP cleavage at a presymptomatic stage resulted in a decrease in the levels of sAPPβ, delay of disease onset and deterioration while at the symptomatic stage there was almost no beneficial effect.

CONCLUSION

APP cleavage products might contribute to the degeneration in ALS, and early inhibition of the APP process may ameliorate disease progression.

Motor deficits, neuron loss, and reduced anxiety coinciding with axonal degeneration and intraneuronal Aβ aggregation in the 5XFAD mouse model of Alzheimer's disease

In the present report, we extend previous findings in the 5XFAD mouse model and demonstrate that these mice develop an age-dependent motor phenotype in addition to working memory deficits and reduced anxiety levels as demonstrated in an elevated plus maze task. Employing a variety of N- and C-terminal specific Aβ antibodies, abundant intraneuronal and plaque-associated pathology, including accumulation of pyroglutamate Aβ, was observed as early as the age of 3 months. Using unbiased stereology, we demonstrate that the 5XFAD mice develop a significant selective neuron loss in layer 5 of the cortex, leaving the overall neuron number of the total frontal cortex and hippocampus unaffected. This observation coincides with the accumulation of intraneuronal Aβ peptides only in cortical Layer 5, but not in CA1, despite comparable APP expression levels. The motor phenotype correlates with abundant spinal cord pathology, as demonstrated by abundant intraneuronal Aβ accumulation and extracellular plaque deposition. In addition, comparable to the APP/PS1KI mouse model, 5XFAD mice develop an age-dependent axonopathy likely contributing to the behavioral deficits.

Concentrations of beta-amyloid precursor protein processing products in cerebrospinal fluid of patients with amyotrophic lateral sclerosis and frontotemporal lobar degeneration

Frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS) are neurodegenerative disorders with heterogeneous clinical presentation but common neuropathological characteristics and pathophysiological substrates, which led to the view of ALS and FTLD representing two manifestations of a clinicopathological spectrum. For both diseases, changes in metabolism of beta-amyloid precursor protein (APP) are reported. In a pilot study, we analyzed cerebrospinal fluid from patients of the ALS-FTLD spectrum for APP processing products. ALS patients show elevated absolute levels of soluble APP and a shift towards the nonamyloidogenic APP processing pathway in contrast to patients with FTLD or ALS + FTLD. Changes in Abeta pattern could be described, allowing separation of patients with pure FTLD from ALS + FTLD. Combination of sAPP and Abeta values improves group differentiation. These findings may provide information on pathophysiological processes in the ALS-FTLD disease spectrum and could have impact in neurochemical diagnosis. We propose to expand this study to larger patient groups comprising followed up cases with known neuropathology.

Regulation of haeme oxygenase-1 for treatment of neuroinflammation and brain disorders

Injury to the CNS elicits a host defense reaction that utilizes astrocytes, microglia, neurons and oligodendrocytes. Neuroinflammation is a major host defense mechanism designed to restore normal structure and function after CNS insult, but like other forms of inflammation, chronic neuroinflammation may contribute to pathogenesis. The inducible haeme oxygenase isoform, haeme oxygenase-1 (HO-1), is a phase 2 enzyme upregulated in response to electrophilic xenobiotics, oxidative stress, cellular injury and disease. There is emerging evidence that HO-1 expression helps mediate the resolution of inflammation, including neuroinflammation. Whether this is solely because of the catabolism of haeme or includes additional mechanisms is unclear. This review provides a brief background on the molecular biology and biochemistry of haeme oxygenases and the actions of haeme, bilirubin, iron and carbon monoxide in the CNS. It then presents our current state of knowledge regarding HO-1 expression in the CNS, regulation of HO-1 induction in neural cells and discusses the prospect of pharmacological manipulation of HO-1 as therapy for CNS disorders. Because of recognized species and cellular differences in HO-1 regulation, a major objective of this review is to draw attention to areas where gaps exist in the experimental record regarding regulation of HO-1 in neural cells. The results indicate the HO-1 system to be an important therapeutic target in CNS disorders, but our understanding of HO-1 expression in human neural cells is severely lacking.

Motor impairment in Alzheimer's disease and transgenic Alzheimer's disease mouse models

In this commentary, we accent the accumulating evidence for motor impairment as a common feature of early Alzheimer's disease (AD) pathology. In addition, we summarize the state of knowledge on this phenotype in experimental mouse models, expressing AD-associated genes like tau or amyloid precursor protein.

Is the modulation of retinoid and retinoid-associated signaling a future therapeutic strategy in neurological trauma and neurodegeneration?

The complex molecular pathways that mediate the effects of vitamin A and its derivatives, are increasingly recognized as a component of the repair capacity that could be activated to induce protection and regeneration in the mature nervous tissue. Retinoid and retinoid-associated signaling plays an essential role in normal neurodevelopment and appears to remain active in the adult CNS. In this paper, we review evidence which supports the hypothesis of an activation of retinoid-associated signaling molecular pathways in the mature nervous tissue and its significance in the context of neurodegenerative, trauma-induced and psychiatric disorders, at spinal and supra-spinal levels. Finally, we summarize the potential therapeutic avenues based on the modulation of retinoid targets undergoing reactivation under conditions of acute injury and chronic degeneration in the central nervous system, and discuss some of the unresolved issues linked to this treatment strategy.