Glucose clearance and uptake is increased in the SOD1G93A mouse model of amyotrophic lateral sclerosis through an insulin-independent mechanism

Alterations to metabolic hormones in amyotrophic lateral sclerosis and frontotemporal dementia postmortem human tissue

Metabolic changes are observed in patients with both amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Although regulation of metabolic processes in the CNS is predominantly carried out within the hypothalamus, extra-hypothalamic CNS areas contain metabolic hormone receptors, including those for leptin (LEPR), insulin (INSR), and neuropeptide Y (NPY), indicating that they may play a role in biological processes underlying pathogenic disease processes. The status of these hormones within regions vulnerable in ALS/FTD is not well described. This study sought to determine whether the expression of these hormones and their receptors is altered in pathology-rich regions in cases of human FTD (superior frontal gyrus and insular cortex) and ALS (primary motor cortex and lumbar spinal cord) with TDP-43 pathology compared to matched healthy controls. LEPR mRNA was increased within the superior frontal gyrus of FTD cases and within primary motor cortex and lumbar spinal cord of ALS cases; INSR mRNA was increased in superior frontal gyrus and insular cortex of FTD cases. NPY protein was decreased in primary motor cortex and lumbar spinal cord of ALS cases. Our results demonstrate that metabolic hormones undergo complex alterations in ALS and FTD and suggest that these hormones could play critical roles in the pathogenesis of these diseases.

Exploring the Role of Metabolic Hormones in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease characterized by progressive loss of motor neurons. Emerging evidence suggests a potential link between metabolic dysregulation and ALS pathogenesis. This study aimed to investigate the relationship between metabolic hormones and disease progression in ALS patients. A cross-sectional study was conducted involving 44 ALS patients recruited from a tertiary care center. Serum levels of insulin, total amylin, C-peptide, active ghrelin, GIP (gastric inhibitory peptide), GLP-1 active (glucagon-like peptide-1), glucagon, PYY (peptide YY), PP (pancreatic polypeptide), leptin, interleukin-6, MCP-1 (monocyte chemoattractant protein-1), and TNFα (tumor necrosis factor alpha) were measured, and correlations with ALSFRS-R, evolution scores, and biomarkers were analyzed using Spearman correlation coefficients. Subgroup analyses based on ALS subtypes, progression pattern of disease, and disease progression rate patterns were performed. Significant correlations were observed between metabolic hormones and ALS evolution scores. Insulin and amylin exhibited strong correlations with disease progression and clinical functional outcomes, with insulin showing particularly robust associations. Other hormones such as C-peptide, leptin, and GLP-1 also showed correlations with ALS progression and functional status. Subgroup analyses revealed differences in hormone levels based on sex and disease evolution patterns, with male patients showing higher amylin and glucagon levels. ALS patients with slower disease progression exhibited elevated levels of amylin and insulin. Our findings suggest a potential role for metabolic hormones in modulating ALS progression and functional outcomes. Further research is needed to elucidate the underlying mechanisms and explore the therapeutic implications of targeting metabolic pathways in ALS management.

Evidence of Metabolic Dysfunction in Amyotrophic Lateral Sclerosis (ALS) Patients and Animal Models

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that affects motor neurons, leading to muscle weakness, paralysis, and eventual death. Research from the past few decades has appreciated that ALS is not only a disease of the motor neurons but also a disease that involves systemic metabolic dysfunction. This review will examine the foundational research of understanding metabolic dysfunction in ALS and provide an overview of past and current studies in ALS patients and animal models, spanning from full systems to various metabolic organs. While ALS-affected muscle tissue exhibits elevated energy demand and a fuel preference switch from glycolysis to fatty acid oxidation, adipose tissue in ALS undergoes increased lipolysis. Dysfunctions in the liver and pancreas contribute to impaired glucose homeostasis and insulin secretion. The central nervous system (CNS) displays abnormal glucose regulation, mitochondrial dysfunction, and increased oxidative stress. Importantly, the hypothalamus, a brain region that controls whole-body metabolism, undergoes atrophy associated with pathological aggregates of TDP-43. This review will also cover past and present treatment options that target metabolic dysfunction in ALS and provide insights into the future of metabolism research in ALS.

Altered Bioenergetics and Metabolic Homeostasis in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease that primarily affects motor neurons and causes muscle atrophy, paralysis, and death. While a great deal of progress has been made in deciphering the underlying pathogenic mechanisms, no effective treatments for the disease are currently available. This is mainly due to the high degree of complexity and heterogeneity that characterizes the disease. Over the last few decades of research, alterations to bioenergetic and metabolic homeostasis have emerged as a common denominator across many different forms of ALS. These alterations are found at the cellular level (e.g., mitochondrial dysfunction and impaired expression of monocarboxylate transporters) and at the systemic level (e.g., low BMI and hypermetabolism) and tend to be associated with survival or disease outcomes in patients. Furthermore, an increasing amount of preclinical evidence and some promising clinical evidence suggests that targeting energy metabolism could be an effective therapeutic strategy. This review examines the evidence both for and against these ALS-associated metabolic alterations and highlights potential avenues for therapeutic intervention.

Alterations in metabolic biomarkers and their potential role in amyotrophic lateral sclerosis

Background

Metabolic dysfunction has been suggested to be involved in the pathophysiology of amyotrophic lateral sclerosis (ALS). This study aimed to investigate the potential role of metabolic biomarkers in the progression of ALS and understand the possible metabolic mechanisms.

Methods

Fifty‐two patients with ALS and 24 normal controls were included, and blood samples were collected for analysis of metabolic biomarkers. Basal anthropometric measures, including body composition and clinical features, were measured in ALS patients. The disease progression rate was calculated using the revised ALS functional rating scale (ALSFRS‐R) during the 6‐month follow‐up.

Results

ALS patients had higher levels of adipokines (adiponectin, adipsin, resistin, and visfatin) and other metabolic biomarkers [C‐peptide, glucagon, glucagon‐like peptide 1 (GLP‐1), gastric inhibitory peptide, and plasminogen activator inhibitor type 1] than controls. Leptin levels in serum were positively correlated with body mass index, body fat, and visceral fat index (VFI). Adiponectin was positively correlated with the VFI and showed a positive correlation with the ALSFRS‐R and a negative correlation with baseline disease progression. Patients with lower body fat, VFI, and fat in limbs showed faster disease progression during follow‐ups. Lower leptin and adiponectin levels were correlated with faster disease progression. After adjusting for confounders, lower adiponectin levels and higher visfatin levels were independently correlated with faster disease progression.

Interpretation

The current study found altered levels of metabolic biomarkers in ALS patients, which may play a role in ALS pathogenesis. Adiponectin and visfatin represent potential biomarkers for prediction of disease progression in ALS.

Combined Treatment with Herbal Medicine and Drug Ameliorates Inflammation and Metabolic Abnormalities in the Liver of an Amyotrophic Lateral Sclerosis Mouse Model

To date, no effective drugs exist for amyotrophic lateral sclerosis (ALS), although riluzole (RZ) and edaravone have been approved for treatment. We previously reported that Bojungikgi-tang (BJIGT) improved motor activity through anti-inflammatory effects in the muscle and spinal cord of hSOD1^G93A mice. Therefore, whether combined treatment with BJIGT and RZ synergistically affects liver function in hSOD1^G93A mice was investigated. Two-month-old male hSOD1^G93A mice were treated with BJIGT (1 mg/g) and RZ (8 μg/g) administered orally for 5 weeks. Drug metabolism and liver function tests of serum and liver homogenates were conducted. mRNA expression levels of cytochrome P450 (CYP) isozymes, inflammatory cytokines, metabolic factors, and mitochondrial oxidative phosphorylation (OXPHOS) subunits were examined using qPCR and Western blotting. Combined administration of BJIGT and RZ did not alter mRNA expression levels of drug-metabolism-related isozymes (CYP1A2 and CYP3A4) but significantly decreased the activity of liver-function-related enzymes (AST, ALT, ALP, and LDH). Increased expression of inflammatory cytokines (IL-1β, TNF-α, and IL-6) and of intracellular stress-related proteins (Bax, AMPKα, JNK, and p38) was reduced by the combined treatment in hSOD1^G93A mice compared to that in control mice. Combined administration reduced the mRNA expression of metabolism-related factors and the expression of OXPHOS subunits. Elevated ATP levels and mitochondrial-fusion-associated protein were decreased after co-administration. Co-administration of BJIGT and RZ did not cause liver damage or toxicity but rather restored liver function in hSOD1^G93A mice. This suggests that this combination can be considered a candidate therapeutic agent for ALS.

Dysregulation of energy homeostasis in amyotrophic lateral sclerosis

PURPOSE OF REVIEW

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease targeting upper and lower motor neurons, inexorably leading to an early death. Defects in energy metabolism have been associated with ALS, including weight loss, increased energy expenditure, decreased body fat mass and increased use of lipid nutrients at the expense of carbohydrates. We review here recent findings on impaired energy metabolism in ALS, and its clinical importance.

RECENT FINDINGS

Hypothalamic atrophy, as well as alterations in hypothalamic peptides controlling energy metabolism, have been associated with metabolic derangements. Recent studies showed that mutations causing familial ALS impact various metabolic pathways, in particular mitochondrial function, and lipid and carbohydrate metabolism, which could underlie these metabolic defects in patients. Importantly, slowing weight loss, through high caloric diets, is a promising therapeutic strategy, and early clinical trials indicated that it might improve survival in at least a subset of patients. More research is needed to improve these therapeutic strategies, define pharmacological options, and refine the population of ALS patients that would benefit from these approaches.

SUMMARY

Dysfunctional energy homeostasis is a major feature of ALS clinical picture and emerges as a potential therapeutic target.

Metabolic Dysfunction in Spinal Muscular Atrophy

Spinal muscular atrophy (SMA) is an autosomal recessive genetic disorder leading to paralysis, muscle atrophy, and death. Significant advances in antisense oligonucleotide treatment and gene therapy have made it possible for SMA patients to benefit from improvements in many aspects of the once devastating natural history of the disease. How the depletion of survival motor neuron (SMN) protein, the product of the gene implicated in the disease, leads to the consequent pathogenic changes remains unresolved. Over the past few years, evidence toward a potential contribution of gastrointestinal, metabolic, and endocrine defects to disease phenotype has surfaced. These findings ranged from disrupted body composition, gastrointestinal tract, fatty acid, glucose, amino acid, and hormonal regulation. Together, these changes could have a meaningful clinical impact on disease traits. However, it is currently unclear whether these findings are secondary to widespread denervation or unique to the SMA phenotype. This review provides an in-depth account of metabolism-related research available to date, with a discussion of unique features compared to other motor neuron and related disorders.