Typical Amyotrophic Lateral Sclerosis Research Articles

Allele-specific silencing of a dominant SETX mutation in familial amyotrophic lateral sclerosis type 4.

Amyotrophic lateral sclerosis 4 (ALS4) is an autosomal dominant motor neuron disease that is molecularly characterized by reduced R-loop levels and caused by pathogenic variants in senataxin (SETX). SETX encodes an RNA/DNA helicase that resolves three-stranded nucleic acid structures called R-loops. Currently, there are no disease-modifying therapies available for ALS4. Given that SETX is haplosufficient, removing the product of the mutated allele presents a potential therapeutic strategy. We designed a series of siRNAs to selectively target the RNA transcript from the ALS4 allele containing the c.1166T>C mutation (p.Leu389Ser). Transfection of HEK293 cells with siRNA and plasmids encoding either wild-type or mutant (Leu389Ser) epitope tagged SETX revealed that three siRNAs specifically reduced mutant SETX protein levels without affecting the wild-type SETX protein. In ALS4 primary fibroblasts, siRNA treatment silenced the endogenous mutant SETX allele, while sparing the wild-type allele, and restored R-loop levels in patient cells. Our findings demonstrate that mutant SETX, differing from wild-type by a single nucleotide, can be effectively and specifically silenced by RNA interference, highlighting the potential of allele-specific siRNA as a therapeutic approach for ALS4.

ALS-Linked VapB P56S Mutation Alters Neuronal Mitochondrial Turnover at the Synapse.

Mitochondrial population maintenance in neurons is essential for neuron function and survival. Contact sites between mitochondria and the endoplasmic reticulum (ER) are poised to regulate mitochondrial homeostasis in neurons. These contact sites can facilitate transfer of calcium and lipids between the organelles and have been shown to regulate aspects of mitochondrial dynamics. Vesicle-associated membrane protein-associated protein B (VapB) is an ER membrane protein present at a subset of ER-mitochondrial contact sites. A proline-to-serine mutation in VapB at amino acid 56 (P56S) correlates with susceptibility to amyotrophic lateral sclerosis (ALS) type 8. Given the relationship between failed mitochondrial health and neurodegenerative disease, we investigated the function of VapB in mitochondrial population maintenance. We demonstrated that transgenic expression of VapBP56S in zebrafish larvae (sex undetermined) increased mitochondrial biogenesis, causing increased mitochondrial population size in the axon terminal. Expression of wild-type VapB did not alter biogenesis but, instead, increased mitophagy in the axon terminal. Using genetic manipulations to independently increase mitochondrial biogenesis, we show that biogenesis is normally balanced by mitophagy to maintain a constant mitochondrial population size. VapBP56S transgenics fail to increase mitophagy to compensate for the increase in mitochondrial biogenesis, suggesting an impaired mitophagic response. Finally, using a synthetic ER-mitochondrial tether, we show that VapB's function in mitochondrial turnover is likely independent of ER-mitochondrial tethering by contact sites. Our findings demonstrate that VapB can control mitochondrial turnover in the axon terminal, and this function is altered by the P56S ALS-linked mutation.

Causal relationship between imaging-derived phenotypes and neurodegenerative diseases: a Mendelian randomization study.

Neurodegenerative diseases are incurable conditions that lead to gradual and progressive deterioration of brain function in patients. With the aging population, the prevalence of these diseases is expected to increase, posing a significant economic burden on society. Imaging techniques play a crucial role in the diagnosis and monitoring of neurodegenerative diseases. This study utilized a two-sample Mendelian randomization (MR) analysis to assess the causal relationship between different imaging-derived phenotypes (IDP) in the brain and neurodegenerative diseases. Multiple MR methods were employed to minimize bias and obtain reliable estimates of the potential causal relationship between the variable exposures of interest and the outcomes. The study found potential causal relationships between different IDPs and Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS), and frontotemporal dementia (FTD). Specifically, the study identified potential causal relationships between 2 different types of IDPs and AD, 8 different types of IDPs and PD, 11 different types of imaging-derived phenotypes and ALS, 1 type of IDP and MS, and 1 type of IDP and FTD. This study provides new insights for the prevention, diagnosis, and treatment of neurodegenerative diseases, offering important clues for understanding the pathogenesis of these diseases and developing relevant intervention strategies.

Role of senataxin in R-loop-mediated neurodegeneration.

Senataxin is an RNA:DNA helicase that plays an important role in the resolution of RNA:DNA hybrids (R-loops) formed during transcription. R-loops are involved in the regulation of biological processes such as immunoglobulin class switching, gene expression and DNA repair. Excessive accumulation of R-loops results in DNA damage and loss of genomic integrity. Senataxin is critical for maintaining optimal levels of R-loops to prevent DNA damage and acts as a genome guardian. Within the nucleus, senataxin interacts with various RNA processing factors and DNA damage response and repair proteins. Senataxin interactors include survival motor neuron and zinc finger protein 1, with whom it co-localizes in sub-nuclear bodies. Despite its ubiquitous expression, mutations in senataxin specifically affect neurons and result in distinct neurodegenerative diseases such as amyotrophic lateral sclerosis type 4 and ataxia with oculomotor apraxia type 2, which are attributed to the gain-of-function and the loss-of-function mutations in senataxin, respectively. In addition, low levels of senataxin (loss-of-function) in spinal muscular atrophy result in the accumulation of R-loops causing DNA damage and motor neuron degeneration. Senataxin may play multiple functions in diverse cellular processes; however, its emerging role in R-loop resolution and maintenance of genomic integrity is gaining attention in the field of neurodegenerative diseases. In this review, we highlight the role of senataxin in R-loop resolution and its potential as a therapeutic target to treat neurodegenerative diseases.

Prediction of caregiver psychological distress in amyotrophic lateral sclerosis: A cross-sectional study.

To propose a predictive model for caregivers' psychological distress (including anxiety, depression, and cognitive overload) based on different data gathered from amyotrophic lateral sclerosis (ALS) patients (cognitive level, psychological distress, type of ALS, and sex). A cross-sectional study with a sample of 51 ALS patients and their respective main carers. Various instruments were used such as the Beck Anxiety Inventory, ALS Depression Inventory-12, and the Edinburgh Cognitive and Behavioral ALS Screen, Zarit Burden Interview, Self-Rating Depression Scale, and Self-Rating Anxiety Scale for caregivers. ALS type, sex, and cognition were predictive variables for caregiver distress, with the main explanatory variable being the distress of the patients themselves. Spinal ALS led to higher psychological distress in caregivers (β = .38), as did male patients with ALS and preserved cognition. The proposed confirmatory model demonstrates that patients' psychological distress is the best predictor of psychological distress in their caregivers. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Spinal cord neurone loss and foot placement changes in a rat knock-in model of amyotrophic lateral sclerosis type 8

Abstract Amyotrophic Lateral Sclerosis is an age-dependent cell type-selective degenerative disease. Genetic studies indicate that Amyotrophic Lateral Sclerosis is part of a spectrum of disorders ranging from spinal muscular atrophy to frontotemporal dementia that share common pathological mechanisms. Amyotrophic Lateral Sclerosis type 8 is a familial disease caused by mis-sense mutations in VAPB. VAPB is localised to the cytoplasmic surface of the endoplasmic reticulum where it serves as a docking point for cytoplasmic proteins and mediates inter-organelle interactions with the endoplasmic reticulum membrane. A gene knock-in model of Amyotrophic Lateral Sclerosis type 8 based on the VapBP56S mutation and VapB gene deletion have been generated in the rat. These animals display a range of age-dependent phenotypes distinct from those previously reported in mouse models of Amyotrophic Lateral Sclerosis type 8. A loss of motor neurones in VapBP56S/+ and VapBP56S/P56Sanimals is indicated by a reduction in the number of large choline acetyl transferase-staining cells in the spinal cord. VapB-/-animals exhibit a relative increase in cytoplasmic TDP-43 levels compared to the nucleus, but no large protein aggregates. Concomitant with these spinal cord pathologies VapBP56S/+, VapBP56S/P56S and VapB-/-animals exhibit age-dependent changes in paw placement and exerted pressures when traversing a CatWalk apparatus, consistent with a somatosensory dysfunction. Extra motor dysfunction is reported in half the cases of motor neurone disease, and this is the first indication of an associated sensory dysfunction in a rodent model of Amyotrophic Lateral Sclerosis. Different rodent models may offer complementary experimental platforms with which to understand the human disease.

Memory for emotional information in sporadic and Type 8 amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is often shown to cause episodic memory deficits. Here, we investigated whether such memory deficits are differentially expressed according to the emotional valence of stimuli and whether they are similarly reproduced in both individuals with sporadic ALS (sALS) and familial Type 8 ALS (ALS8). Twenty individuals with sALS, 18 individuals with ALS8, and 19 healthy controls were recruited for the study. After a neuropsychological and psychopathological assessment, all participants responded to a recognition memory test wherein images varying in terms of valence were initially shown. After a short interval, the images were shown again intermixed with new images, and the participants' task was to indicate whether each image was "old" or "new" and to estimate the confidence in their responses. Both the sALS and the ALS8 groups showed significantly lower recognition of positive relative to negative valence images (d = 0.92 and d = 0.74, respectively), an effect that was completely absent for healthy controls (d = 0.17). These effects were qualified by a significant interaction involving the factors of valence and group (ηp² = 0.12). The current findings demonstrate that sALS and ALS8 are associated with decreased recognition of emotional information, an effect that is nonetheless restricted to positive valence stimuli. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Discovery of a novel homozygous SOD1 truncating variant bolsters infantile SOD1 deficiency syndrome.

Superoxide dismutase 1 (SOD1) is an important antioxidant enzyme whose main function is to neutralise superoxide free radicals in the cytoplasm. Heterozygous variants in SOD1 are responsible for a substantial percentage of familial amyotrophic lateral sclerosis (ALS) cases. Recently, several reports have shown that biallelic loss of SOD1 function results in a novel phenotype called infantile SOD1 deficiency syndrome, which is consistent with a recessive pattern of inheritance and can be distinguished from typical (adult-onset) ALS. We documented detailed family histories and clinical data, followed by whole-exome sequencing and family co-segregation analysis through Sanger sequencing. To facilitate comparisons, relevant data from fifteen previously reported patients with SOD1-related neurodevelopmental disorders were included. This study presents a new Turkish family with two affected children exhibiting severe delayed motor development, infancy-onset loss of motor skills, axial hypotonia, tetraspasticity, and impaired cognitive functions. Genetic analysis revealed a novel homozygous frameshift variant in SOD1 (c.248dupG [p.Asp84Argfs*8]), with computational biochemical studies shedding light on the mechanistic aspects of SOD1 dysfunction. Our findings contribute an affirmative report of a fourth biallelic variant resulting in a severe clinical phenotype, reminiscent of those induced by previously identified homozygous loss-of-function SOD1 variants. This research not only advances our understanding of the pathogenesis of this debilitating neurological syndrome but also aligns with ongoing intensive efforts to comprehend and address SOD1-linked ALS.

CHCHD10S59L/+ mouse model: Behavioral and neuropathological features of frontotemporal dementia

CHCHD10-related disease causes a spectrum of clinical presentations including mitochondrial myopathy, cardiomyopathy, amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). We generated a knock-in mouse model bearing the p.Ser59Leu (S59L) CHCHD10 variant. Chchd10S59L/+ mice have been shown to phenotypically replicate the disorders observed in patients: myopathy with mtDNA instability, cardiomyopathy and typical ALS features (protein aggregation, neuromuscular junction degeneration and spinal motor neuron loss). Here, we conducted a comprehensive behavioral, electrophysiological and neuropathological assessment of Chchd10S59L/+ mice. These animals show impaired learning and memory capacities with reduced long-term potentiation (LTP) measured at the Perforant Pathway-Dentate Gyrus (PP-DG) synapses. In the hippocampus of Chchd10S59L/+ mice, neuropathological studies show the involvement of protein aggregates, activation of the integrated stress response (ISR) and neuroinflammation in the degenerative process. These findings contribute to decipher mechanisms associated with CHCHD10 variants linking mitochondrial dysfunction and neuronal death. They also validate the Chchd10S59L/+ mice as a relevant model for FTD, which can be used for preclinical studies to test new therapeutic strategies for this devastating disease.

Whole-body fasciculation detection in amyotrophic lateral sclerosis using motor unit MRI

ObjectiveCompare fasciculation rates between amyotrophic lateral sclerosis (ALS) patients and healthy controls in body regions relevant for diagnosing ALS using motor unit MRI (MUMRI) at baseline and 6 months follow-up, and relate this to single-channel surface EMG (SEMG). MethodsTongue, biceps brachii, paraspinals and lower legs were assessed with MUMRI and biceps brachii and soleus with SEMG in 10 healthy controls and 10 patients (9 typical ALS, 1 primary lateral sclerosis [PLS]). ResultsMUMRI-detected fasciculation rates in typical ALS patients were higher compared to healthy controls for biceps brachii (2.40 ± 1.90 cm-3min−1vs. 0.04 ± 0.10 cm-3min−1, p = 0.004), paraspinals (1.14 ± 1.61 cm-3min−1vs. 0.02 ± 0.02 cm-3min−1, p = 0.016) and lower legs (1.42 ± 1.27 cm-3min−1vs. 0.13 ± 0.10 cm-3min−1, p = 0.004), but not tongue (1.41 ± 1.94 cm-3min−1vs. 0.18 ± 0.18 cm-3min−1, p = 0.556). The PLS patient showed no fasciculation. At baseline, 6/9 ALS patients had increased fasciculation rates compared to healthy controls in at least 2 body regions. At follow-up every patient had increased fasciculation rates in at least 2 body regions. The MUMRI-detected fasciculation rate correlated with SEMG-detected fasciculation rates (τ = 0.475, p = 0.006). ConclusionMUMRI can non-invasively image fasciculation in multiple body regions and appears sensitive to disease progression in individual patients. SignificanceMUMRI has potential as diagnostic tool for ALS.

Rab11a Controls Cell Shape via C9orf72 Protein: Possible Relationships to Frontotemporal Dementia/Amyotrophic Lateral Sclerosis (FTDALS) Type 1.

Abnormal nucleotide insertions of C9orf72, which forms a complex with Smith-Magenis syndrome chromosomal region candidate gene 8 (SMCR8) protein and WD repeat-containing protein 41 (WDR41) protein, are associated with an autosomal-dominant neurodegenerative frontotemporal dementia and/or amyotrophic lateral sclerosis type 1 (FTDALS1). The differentially expressed in normal and neoplastic cells (DENN) domain-containing C9orf72 and its complex with SMCR8 and WDR41 function as a guanine-nucleotide exchange factor for Rab GTP/GDP-binding proteins (Rab GEF, also called Rab activator). Among Rab proteins serving as major effectors, there exists Rab11a. However, it remains to be established which Rab protein is related to promoting or sustaining neuronal morphogenesis or homeostasis. In this study, we describe that the knockdown of Rab11a decreases the expression levels of neuronal differentiation marker proteins, as well as the elongation of neurite-like processes, using N1E-115 cells, a well-utilized neuronal differentiation model. Similar results were obtained in primary cortical neurons. In contrast, the knockdown of Rab11b, a Rab11a homolog, did not significantly affect their cell morphological changes. It is of note that treatment with hesperetin, a citrus flavonoid (also known as Vitamin P), recovered the neuronal morphological phenotypes induced by Rab11a knockdown. Also, the knockdown of Rab11a or Rab11b led to a decrease in glial marker expression levels and in morphological changes in FBD-102b cells, which serve as the oligodendroglial differentiation model. Rab11a is specifically involved in the regulation of neuronal morphological differentiation. The knockdown effect mimicking the loss of function of C9orf72 is reversed by treatment with hesperetin. These findings may reveal a clue for identifying one of the potential molecular and cellular phenotypes underlying FTDALS1.

Modulating Golgi Stress Signaling Ameliorates Cell Morphological Phenotypes Induced by CHMP2B with Frontotemporal Dementia-Associated p.Asp148Tyr.

Some charged multivesicular body protein 2B (CHMP2B) mutations are associated with autosomal-dominant neurodegenerative frontotemporal dementia and/or amyotrophic lateral sclerosis type 7 (FTDALS7). The main aim of this study is to clarify the relationship between the expression of mutated CHMP2B protein displaying FTD symptoms and defective neuronal differentiation. First, we illustrate that the expression of CHMP2B with the Asp148Tyr (D148Y) mutation, which preferentially displays FTD phenotypes, blunts neurite process elongation in rat primary cortical neurons. Similar results were observed in the N1E-115 cell line, a model that undergoes neurite elongation. Second, these effects were also accompanied by changes in neuronal differentiation marker protein expression. Third, wild-type CHMP2B protein was indeed localized in the endosomal sorting complexes required to transport (ESCRT)-like structures throughout the cytoplasm. In contrast, CHMP2B with the D148Y mutation exhibited aggregation-like structures and accumulated in the Golgi body. Fourth, among currently known Golgi stress regulators, the expression levels of Hsp47, which has protective effects on the Golgi body, were decreased in cells expressing CHMP2B with the D148Y mutation. Fifth, Arf4, another Golgi stress-signaling molecule, was increased in mutant-expressing cells. Finally, when transfecting Hsp47 or knocking down Arf4 with small interfering (si)RNA, cellular phenotypes in mutant-expressing cells were recovered. These results suggest that CHMP2B with the D148Y mutation, acting through Golgi stress signaling, is negatively involved in the regulation of neuronal cell morphological differentiation, providing evidence that a molecule controlling Golgi stress may be one of the potential FTD therapeutic targets at the molecular and cellular levels.

Simple models to understand complex disease: 10 years of progress from Caenorhabditis elegans models of amyotrophic lateral sclerosis and frontotemporal lobar degeneration.

The nematode Caenorhabditis elegans are a powerful model system to study human disease, with numerous experimental advantages including significant genetic and cellular homology to vertebrate animals, a short lifespan, and tractable behavioral, molecular biology and imaging assays. Beginning with the identification of SOD1 as a genetic cause of amyotrophic lateral sclerosis (ALS), C. elegans have contributed to a deeper understanding of the mechanistic underpinnings of this devastating neurodegenerative disease. More recently this work has expanded to encompass models of other types of ALS and the related disease frontotemporal lobar degeneration (FTLD-TDP), including those characterized by mutation or accumulation of the proteins TDP-43, C9orf72, FUS, HnRNPA2B1, ALS2, DCTN1, CHCHD10, ELP3, TUBA4A, CAV1, UBQLN2, ATXN3, TIA1, KIF5A, VAPB, GRN, and RAB38. In this review we summarize these models and the progress and insights from the last ten years of using C. elegans to study the neurodegenerative diseases ALS and FTLD-TDP.

Relationships among Speech Intelligibility, Speech Rate, and Maximum Tongue Pressure in Patients with Bulbar Paralysis Type of Amyotrophic Lateral Sclerosis

Relationships among Speech Intelligibility, Speech Rate, and Maximum Tongue Pressure in Patients with Bulbar Paralysis Type of Amyotrophic Lateral Sclerosis

IFNγ protects motor neurons from oxidative stress via enhanced global protein synthesis in FUS-associated amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis type 6 (ALS6) is a familial subtype of ALS linked to Fused in Sarcoma (FUS) gene mutation. FUS mutations lead to decreased global protein synthesis, but the mechanism that drives this has not been established. Here, we used ALS6 patient-derived induced pluripotent stem cells (hIPSCs) to study the effect of the ALS6 FUSR521H mutation on the translation machinery in motor neurons (MNs). We find, in agreement with findings of others, that protein synthesis is decreased in FUSR521H MNs. Furthermore, FUSR521H MNs are more sensitive to oxidative stress and display reduced expression of TGF-β and mTORC gene pathways when stressed. Finally, we show that IFNγ treatment reduces apoptosis of FUSR521H MNs exposed to oxidative stress and partially restores the translation rates in FUSR521H MNs. Overall, these findings suggest that a functional IFNγ response is important for FUS-mediated protein synthesis, possibly by FUS nuclear translocation in ALS6.

FTD/ALS Type 7-Associated Thr104Asn Mutation of CHMP2B Blunts Neuronal Process Elongation, and Is Recovered by Knockdown of Arf4, the Golgi Stress Regulator.

Frontotemporal dementia and/or amyotrophic lateral sclerosis type 7 (FTD/ALS7) is an autosomal dominant neurodegenerative disorder characterized by the onset of FTD and/or ALS, mainly in adulthood. Patients with some types of mutations, including the Thr104Asn (T104N) mutation of charged multivesicular body protein 2B (CHMP2B), have predominantly ALS phenotypes, whereas patients with other mutations have predominantly FTD phenotypes. A few mutations result in patients having both phenotypes approximately equally; however, the reason why phenotypes differ depending on the position of the mutation is unknown. CHMP2B comprises one part of the endosomal sorting complexes required for transport (ESCRT), specifically ESCRT-III, in the cytoplasm. We describe here, for the first time, that CHMP2B with the T104N mutation inhibits neuronal process elongation in the N1E-115 cell line, a model line undergoing neuronal differentiation. This inhibitory phenotype was accompanied by changes in marker protein expression. Of note, CHMP2B with the T104N mutation, but not the wild-type form, was preferentially accumulated in the Golgi body. Of the four major Golgi stress signaling pathways currently known, the pathway through Arf4, the small GTPase, was specifically upregulated in cells expressing CHMP2B with the T104N mutation. Conversely, knockdown of Arf4 with the cognate small interfering (si)RNA recovered the neuronal process elongation inhibited by the T104N mutation. These results suggest that the T104N mutation of CHMP2B inhibits morphological differentiation by triggering Golgi stress signaling, revealing a possible therapeutic molecular target for recovering potential molecular and cellular phenotypes underlying FTD/ALS7.

Yeast Models of Amyotrophic Lateral Sclerosis Type 8 Mimic Phenotypes Seen in Mammalian Cells Expressing Mutant VAPBP56S.

Amyotrophic lateral sclerosis (ALS) is a complex neurodegenerative disease that results in the loss of motor neurons and can occur sporadically or due to genetic mutations. Among the 30 genes linked to familial ALS, a P56S mutation in VAPB, an ER-resident protein that functions at membrane contact sites, causes ALS type 8. Mammalian cells expressing VAPBP56S have distinctive phenotypes, including ER collapse, protein and/or membrane-containing inclusions, and sensitivity to ER stress. VAPB is conserved through evolution and has two homologs in budding yeast, SCS2 and SCS22. Previously, a humanized version of SCS2 bearing disease-linked mutations was described, and it caused Scs2-containing inclusions when overexpressed in yeast. Here, we describe a yeast model for ALS8 in which the two SCS genes are deleted and replaced with a single chromosomal copy of either wild-type or mutant yeast SCS2 or human VAPB expressed from the SCS2 promoter. These cells display ER collapse, the formation of inclusion-like structures, and sensitivity to tunicamycin, an ER stress-inducing drug. Based on the phenotypic similarity to mammalian cells expressing VAPBP56S, we propose that these models can be used to study the molecular basis of cell death or dysfunction in ALS8. Moreover, other conserved ALS-linked genes may create opportunities for the generation of yeast models of disease.

A comparative study of cognitive and behavioral profiles between sporadic and type 8 amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) type 8 (ALS8) is caused by VAPB gene mutations. The differences between neuropsychological and behavioral profiles of patients with sporadic ALS (sALS) and those with ALS8 are unclear. We aimed to compare cognitive performance and behavioral aspects between sALS and ALS8 patients. Our study included 29 symptomatic ALS8 patients (17 men; median age 49 years), 20 sALS patients (12 men; median age 55 years), and 30 healthy controls (16 men; median age 50 years), matched for sex, age, and education. Participants underwent neuropsychological assessments focused on executive functions, visual memory, and facial emotion recognition. Behavioral and psychiatric symptoms were evaluated using the Hospital Anxiety and Depression Scale and the Cambridge Behavioral Inventory. Clinical groups (sALS and ALS8) exhibited lower global cognitive efficiency and impaired cognitive flexibility, processing speed, and inhibitory control compared with controls. ALS8 and sALS showed similar performance in most executive tests, except for poorer verbal (lexical) fluency in those with sALS. Apathy, anxiety, and stereotypical behaviors were frequent in both clinical groups. sALS and ALS8 patients demonstrated similar deficits in most cognitive domains and had comparable behavioral profiles. These findings should be considered in the care of patients.

The impact of upper and lower motor neuron burden on diagnostic certainty, and clinical course of spinal-onset amyotrophic lateral sclerosis: a cluster-based approach.

Upper motor neuron (UMN) and lower motor neuron (LMN) involvement represent the core clinical features of amyotrophic lateral sclerosis (ALS). Several studies divided patients into prevalent UMN and LMN impairment phenotypes to investigate the association between motor systems impairments and ALS clinical course. However, this distinction was somehow heterogeneous and significantly affected the comparability across studies. This study aimed to investigate whether patients spontaneously segregate based on the extent of UMN and LMN involvement without a-priori categorization and to identify potential clinical and prognostic features of different clusters. Eighty-eight consecutive spinal-onset ALS patients were referred to an ALS tertiary center between 2015 and 2022. UMN and LMN burden was assessed with the Penn Upper Motor Neuron scale (PUMNS) and the Devine score, respectively. PUMNS and LMN scores were normalized into 0-1 and analyzed using a two-step cluster analysis and the Euclidean distance measure. The Bayesian Information Criterion was used to determine the cluster number. Demographic and clinical variables were tested for differences among the clusters. Three distinct clusters emerged at cluster analysis. Patients in "cluster-1" showed moderate UMN and severe LMN involvement, corresponding to the typical ALS phenotype. Patients in "cluster-2" showed mild LMN and severe UMN damage, corresponding to a predominant UMN phenotype, while "cluster-3" patients showed mild UMN and moderate LMN damage, corresponding to a predominant LMN phenotype. Patients in "cluster-1" and "cluster-2" showed a higher prevalence of definite ALS than those in "cluster-3" (61% and 46 vs 9%, p < 0.001). "Cluster-1" patients had a lower median ALSFRS-r score compared to both "cluster-2" and 3 patients (27 vs 40 and 35, < 0.001). "Cluster-1" (HR: 8.5; 95% CI 2.1-35.1 and p = 0.003) and 3 (HR: 3.2; 95% CI 1.1-9.1; p = 0.03) were associated with shorter survival than those in "cluster-2". Spinal-onset ALS can be categorized into three groups according to LMN and UMN burden. The UMN burden is related to higher diagnostic certainty and broader disease spread, while LMN involvement is associated with higher disease severity and shorter survival.

Role of Oxidative Stress on the Etiology and Pathophysiology of Amyotrophic Lateral Sclerosis (ALS) and Its Relation with the Enteric Nervous System

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease affecting motor neurons in the spinal cord, cerebral cortex, and medulla oblongata. Most patients present a clinical phenotype of classic ALS-with predominant atrophy, muscle weakness, and fasciculations-and survival of 3 to 5 years following diagnosis. In the present review, we performed a literature search to provide an update on the etiology and pathophysiological mechanisms involved in ALS. There are two types of ALS: the familial form with genetic involvement, and the sporadic form with a multifactorial origin. ALS pathophysiology is characterized by involvement of multiple processes, including oxidative stress, glutamate excitotoxicity, and neuroinflammation. Moreover, it is proposed that conditioning risk factors affect ALS development, such as susceptibility to neurodegeneration in motor neurons, the intensity of performed physical activity, and intestinal dysbiosis with involvement of the enteric nervous system, which supports the existing theories of disease generation. To improve patients' prognosis and survival, it is necessary to further deepen our understanding of the etiopathogenesis of ALS.