Multiple pathways of lipid dysregulation in amyotrophic lateral sclerosis

Lipid Metabolism and Statin Therapy in Neurodegenerative Diseases: An Endocrine View

Background/aim: A growing body of evidence suggests a link between dyslipidemias and neurodegenerative diseases, highlighting the crucial role of lipid metabolism in the health of the central nervous system. The aim of our work was to provide an update on this topic, with a focus on clinical practice from an endocrinological point of view. Endocrinologists, being experts in the management of dyslipidemias, can play a key role in the prevention and treatment of neurodegenerative conditions, through precocious and effective lipid profile optimization. Methods: The literature was scanned to identify clinical trials and correlation studies on the association between dyslipidemia, statin therapy, and the following neurodegenerative diseases: Alzheimer's disease (AD), Parkisons's disease (PD), Multiple sclerosis (MS), and Amyotrophic lateral sclerosis (ALS). Results: Impaired lipid homeostasis, such as that frequently observed in patients affected by obesity and diabetes, is related to neurodegenerative diseases, such as AD, PD, and other cognitive deficits related to aging. AD and related dementias are now a real priority health problem. In the United States, there are approximately 7 million subjects aged 65 and older living with AD and related dementias, and this number is projected to grow to 12 million in the coming decades. Lipid-lowering therapy with statins is an effective strategy in reducing serum low-density lipoprotein cholesterol to normal range concentrations and, therefore, cardiovascular disease risk; moreover, statins have been reported to have a positive effect on neurodegenerative diseases. Conclusions: Several pieces of research have found inconsistent information following our review. There was no association between statin use and ALS incidence. More positive evidence has emerged regarding statin use and AD/PD. However, further large-scale prospective randomized control trials are required to properly understand this issue.

Emerging Ferroptosis Involvement in Amyotrophic Lateral Sclerosis Pathogenesis: Neuroprotective Activity of Polyphenols

Neurodegenerative diseases are a group of diseases that share common features, such as the generation of misfolded protein deposits and increased oxidative stress. Among them, amyotrophic lateral sclerosis (ALS), whose pathogenesis is still not entirely clear, is a complex neurodegenerative disease linked both to gene mutations affecting different proteins, such as superoxide dismutase 1, Tar DNA binding protein 43, Chromosome 9 open frame 72, and Fused in Sarcoma, and to altered iron homeostasis, mitochondrial dysfunction, oxidative stress, and impaired glutamate metabolism. The purpose of this review is to highlight the molecular targets common to ALS and ferroptosis. Indeed, many pathways implicated in the disease are hallmarks of ferroptosis, a recently discovered type of iron-dependent programmed cell death characterized by increased reactive oxygen species (ROS) and lipid peroxidation. Iron accumulation results in mitochondrial dysfunction and increased levels of ROS, lipid peroxidation, and ferroptosis triggers; in addition, the inhibition of the Xc- system results in reduced cystine levels and glutamate accumulation, leading to excitotoxicity and the inhibition of GPx4 synthesis. These results highlight the potential involvement of ferroptosis in ALS, providing new molecular and biochemical targets that could be exploited in the treatment of the disease using polyphenols.

Longitudinal Metabolomics in Amyotrophic Lateral Sclerosis Implicates Impaired Lipid Metabolism

OBJECTIVE

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by altered metabolome and energy homeostasis, manifesting with body mass index changes and hypermetabolism-both prognostic of disease progression and survival. The cross-sectional ALS metabolome has been characterized, but longitudinal correlations to functional decline are lacking.

METHODS

We longitudinally evaluated metabolomes from ALS plasma and terminal postmortem spinal cord and brain motor cortex tissue. We constructed 3 plasma models. A linear mixed effects model correlated all metabolite levels across all timepoints to their corresponding functional scores. An interaction model predicted a longitudinal change in function from baseline metabolites, whereas a progression model identified metabolites linked to a 20% or 50% drop in function. In postmortem samples, differential metabolites in onset versus second spinal cord segments served as a surrogate of disease progression. Mendelian randomization assessed potential causality from metabolites.

RESULTS

In plasma, all models primarily selected lipid metabolites and sub-pathways, in addition to amino acids, xenobiotics, and various less frequently selected pathways. Among lipids, fatty acids and sphingomyelins were predominant, along with plasmalogens, phosphatidylcholines, and lysophospholipids. Sex interaction findings were nominal. In the spinal cord, sphingomyelin and long-chain saturated and monounsaturated fatty acids were more abundant in the onset segment tissue, whereas phosphatidylcholines and phosphatidylethanolamines were less abundant. Mendelian randomization suggested that impaired carnitine and short chain acylcarnitine metabolism may be genetically determined in ALS, along with various antioxidant derivatives.

INTERPRETATION

Our findings suggest metabolomic changes primarily involving different lipid classes and carnitine metabolism may underscore ALS severity and progression. ANN NEUROL 2025.

Oxidative Stress-mediated Lipid Peroxidation-derived Lipid Aldehydes in the Pathophysiology of Neurodegenerative Diseases

Neurodegenerative diseases such as Alzheimer's, Parkinson's, and amyotrophic lateral sclerosis cause damage and gradual loss of neurons affecting the central nervous system. Neurodegenerative diseases are most commonly seen in the ageing process. Ageing causes increased reactive oxygen species and decreased mitochondrial ATP generation, resulting in redox imbalance and oxidative stress. Oxidative stress-generated free radicals cause damage to membrane lipids containing polyunsaturated fatty acids, leading to the formation of toxic lipid aldehyde products such as 4- hydroxynonenal and malondialdehyde. Several studies have shown that lipid peroxidation-derived aldehyde products form adducts with cellular proteins, altering their structure and function. Thus, these lipid aldehydes could act as secondary signaling intermediates, modifying important metabolic pathways, and contributing to the pathophysiology of several human diseases, including neurodegenerative disorders. Additionally, they could serve as biomarkers for disease progression. This narrative review article discusses the biological and clinical significance of oxidative stress-mediated lipid peroxidation-derived lipid aldehydes in the pathophysiology of various neurodegenerative diseases.

Common lipidomic signatures across distinct acute brain injuries in patient outcome prediction

Lipidomic alterations have been associated with various neurological diseases. Examining temporal changes in serum lipidomic profiles, irrespective of injury type, reveals promising prognostic indicators. In this longitudinal prospective observational study, serum samples were collected early (46 ± 24 h) and late (142 ± 52 h) post-injury from 70 patients with ischemic stroke, aneurysmal subarachnoid hemorrhage, and traumatic brain injury that had outcomes dichotomized as favorable (modified Rankin Scores (mRS) 0-3) and unfavorable (mRS 4-6) three months post-injury. Lipidomic profiling of 1153 lipids, analyzed using statistical and machine learning methods, identified 153 lipids with late-stage significant outcome differences. Supervised machine learning pinpointed 12 key lipids, forming a combinatory prognostic equation with high discriminatory power (AUC 94.7 %, sensitivity 89 %, specificity 92 %; p < 0.0001). Enriched functions of the identified lipids were related to sphingolipid signaling, glycerophospholipid metabolism, and necroptosis (p < 0.05, FDR-corrected). The study underscores the dynamic nature of lipidomic profiles in acute brain injuries, emphasizing late-stage distinctions and proposing lipids as significant prognostic markers, transcending injury types. These findings advocate further exploration of lipidomic changes for a comprehensive understanding of pathobiological roles and enhanced prediction for recovery trajectories.

The Role of Cardiolipin in Mitochondrial Function and Neurodegenerative Diseases

Cardiolipin (CL) is a mitochondria-exclusive phospholipid synthesized in the inner mitochondrial membrane. CL plays a key role in mitochondrial membranes, impacting a plethora of functions this organelle performs. Consequently, it is conceivable that abnormalities in the CL content, composition, and level of oxidation may negatively impact mitochondrial function and dynamics, with important implications in a variety of diseases. This review concentrates on papers published in recent years, combined with basic and underexplored research in CL. We capture new findings on its biological functions in the mitochondria, as well as its association with neurodegenerative diseases such as Alzheimer's disease or Parkinson's disease. Lastly, we explore the potential applications of CL as a biomarker and pharmacological target to mitigate mitochondrial dysfunction.

Evidence for alterations in lipid profiles and biophysical properties of lipid rafts from spinal cord in sporadic amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is an age-dependent neurodegenerative disease affecting motor neurons in the spinal cord and brainstem whose etiopathogenesis remains unclear. Recent studies have linked major neurodegenerative diseases with altered function of multimolecular lipid-protein complexes named lipid rafts. In the present study, we have isolated lipid rafts from the anterior horn of the spinal cords of controls and ALS individuals and analysed their lipid composition. We found that ALS affects levels of different fatty acids, lipid classes and related ratios and indexes. The most significant changes affected the contents of n-9/n-7 monounsaturated fatty acids and arachidonic acid, the main n-6 long-chain polyunsaturated fatty acid (LCPUFA), which were higher in ALS lipid rafts. Paralleling these findings, ALS lipid rafts lower saturates-to-unsaturates ratio compared to controls. Further, levels of cholesteryl ester (SE) and anionic-to-zwitterionic phospholipids ratio were augmented in ALS lipid rafts, while sulfatide contents were reduced. Further, regression analyses revealed augmented SE esterification to (mono)unsaturated fatty acids in ALS, but to saturates in controls. Overall, these changes indicate that lipid rafts from ALS spinal cord undergo destabilization of the lipid structure, which might impact their biophysical properties, likely leading to more fluid membranes. Indeed, estimations of membrane microviscosity confirmed less viscous membranes in ALS, as well as more mobile yet smaller lipid rafts compared to surrounding membranes. Overall, these results demonstrate that the changes in ALS lipid rafts are unrelated to oxidative stress, but to anomalies in lipid metabolism and/or lipid raft membrane biogenesis in motor neurons. KEY MESSAGES: The lipid matrix of multimolecular membrane complexes named lipid rafts are altered in human spinal cord in sporadic amyotrophic lateral sclerosis (ALS). Lipid rafts from ALS spinal cord contain higher levels of n-6 LCPUFA (but not n-3 LCPUFA), n-7/n-9 monounsaturates and lower saturates-to-unsaturates ratio. ALS lipid rafts display increased contents of cholesteryl esters, anomalous anionic-to-zwitterionic phospholipids and phospholipid remodelling and reduced sulphated and total sphingolipid levels, compared to control lipid rafts. Destabilization of the lipid structure of lipid raft affects their biophysical properties and leads to more fluid, less viscous membrane microdomains. The changes in ALS lipid rafts are unlikely related to increased oxidative stress, but to anomalies in lipid metabolism and/or raft membrane biogenesis in motor neurons.

Urinary biomarkers for amyotrophic lateral sclerosis: candidates, opportunities and considerations

Amyotrophic lateral sclerosis is a relentless neurodegenerative disease that is mostly fatal within 3-5 years and is diagnosed on evidence of progressive upper and lower motor neuron degeneration. Around 15% of those with amyotrophic lateral sclerosis also have frontotemporal degeneration, and gene mutations account for ∼10%. Amyotrophic lateral sclerosis is a variable heterogeneous disease, and it is becoming increasingly clear that numerous different disease processes culminate in the final degeneration of motor neurons. There is a profound need to clearly articulate and measure pathological process that occurs. Such information is needed to tailor treatments to individuals with amyotrophic lateral sclerosis according to an individual's pathological fingerprint. For new candidate therapies, there is also a need for methods to select patients according to expected treatment outcomes and measure the success, or not, of treatments. Biomarkers are essential tools to fulfil these needs, and urine is a rich source for candidate biofluid biomarkers. This review will describe promising candidate urinary biomarkers of amyotrophic lateral sclerosis and other possible urinary candidates in future areas of investigation as well as the limitations of urinary biomarkers.

Rat Hair Metabolomics Analysis Reveals Perturbations of Unsaturated Fatty Acid Biosynthesis, Phenylalanine, and Arachidonic Acid Metabolism Pathways Are Associated with Amyloid-β-Induced Cognitive Deficits

Hair is a noninvasive valuable biospecimen for the long-term assessment of endogenous metabolic disturbance. Whether the hair is suitable for identifying biomarkers of the Alzheimer's disease (AD) process remains unknown. We aim to investigate the metabolism changes in hair after β-amyloid (Aβ1-42) exposure in rats using ultra-high-performance liquid chromatography-high-resolution mass spectrometry-based untargeted and targeted methods. Thirty-five days after Aβ1-42 induction, rats displayed significant cognitive deficits, and forty metabolites were changed, of which twenty belonged to three perturbed pathways: (1) phenylalanine metabolism and phenylalanine, tyrosine, and tryptophan biosynthesis-L-phenylalanine, phenylpyruvate, ortho-hydroxyphenylacetic acid, and phenyllactic acid are up-regulated; (2) arachidonic acid (ARA) metabolism-leukotriene B4 (LTB4), arachidonyl carnitine, and 5(S)-HPETE are upregulation, but ARA, 14,15-DiHETrE, 5(S)-HETE, and PGB2 are opposite; and (3) unsaturated fatty acid biosynthesis- eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), FA 18:3 + 1O, and FA 18:3 + 2O are downregulated. Linoleic acid metabolism belonging to the biosynthesis of unsaturated fatty acid includes the upregulation of 8-hydroxy-9,10-epoxystearic acid, 13-oxoODE, and FA 18:2 + 4O, and downregulation of 9(S)-HPODE and dihomo-γ-linolenic acid. In addition, cortisone and dehydroepiandrosterone belonging to steroid hormone biosynthesis are upregulated. These three perturbed metabolic pathways also correlate with cognitive impairment after Aβ1-42 stimulation. Furthermore, ARA, DHA, EPA, L-phenylalanine, and cortisone have been previously implicated in the cerebrospinal fluid of AD patients and show a similar changing trend in Aβ1-42 rats' hair. These data suggest hair can be a useful biospecimen that well reflects the expression of non-polar molecules under Aβ1-42 stimulation, and the five metabolites have the potential to serve as novel AD biomarkers.