NMR analysis of the CSF and plasma metabolome of rigorously matched amyotrophic lateral sclerosis, Parkinson’s disease and control subjects

Abstract

Introduction Amyotrophic lateral sclerosis (ALS) and Parkinson's disease (PD) are two severe neurodegenerative disorders for which the disease mechanisms are poorly understood and reliable biomarkers are absent. Objectives To identify metabolite biomarkers for ALS and PD, and to gain insights into which metabolic pathways are involved in disease. Methods Nuclear magnetic resonance (NMR) metabolomics was utilized to characterize the metabolite profiles of cerebrospinal fluid (CSF) and plasma from individuals in three age, gender, and sampling-date matched groups, comprising 22 ALS, 22 PD and 28 control subjects. Results Multivariate analysis of NMR data generated robust discriminatory models for separation of ALS from control subjects. ALS patients showed increased concentrations of several metabolites in both CSF and plasma, these are alanine (CSF fold change = 1.22, p = 0.005), creatine (CSF-fc = 1.17, p = 0.001), glucose (CSFfc = 1.11, p = 0.036), isoleucine (CSF-fc = 1.24, p = 0.002), and valine (CSF-fc = 1.17, p = 0.014). Additional metabolites in CSF (creatinine, dimethylamine and lactic acid) and plasma (acetic acid, glutamic acid, histidine, leucine, pyruvate and tyrosine) were also important for this discrimination. Similarly, panels of CSFmetabolites that discriminate PD from ALS and control subjects were identified. Conclusions The results for the ALS patients suggest an affected creatine/creatinine pathway and an altered branched chain amino acid (BCAA) metabolism, and suggest links to glucose and energy metabolism. Putative metabolic markers specific for ALS (e.g. creatinine and lactic acid) and PD (e.g. 3-hydroxyisovaleric acid and mannose) were identified, while several (e.g. creatine and BCAAs) were shared between ALS and PD, suggesting some overlap in metabolic alterations in these disorders. Keywords Amyotrophic lateral sclerosis (ALS) Á Parkinson's disease (PD) Á NMR metabolomics Á Biomarker Á Cerebrospinal fluid (CSF) Á Plasma Abbreviations ALS Amyotrophic lateral sclerosis PD Parkinson's disease NMR Nuclear magnetic resonance MS Mass spectrometry EDTA Ethylenediaminetetraacetic acid CSF Cerebrospinal fluid CPMG Carr-Purcell-Meiboom-Gill PCA Principal component analysis OPLS Orthogonal projection to latent structures DA Discriminant analysis EP Effect projection CV-ANOVA Analysis of variance testing of crossvalidated predictive residuals CNS Central nervous system BCAA Branched chain amino acids Electronic supplementary material The online version of this article (

Prediagnostic plasma branched-chain amino acids and the risk of amyotrophic lateral sclerosis

“…In a study comparing the metabolome in 22 patients with ALS with 28 controls with other neurologic conditions, the plasma levels of all 3 BCAAs were higher in patients with ALS compared to controls in analyses using nuclear magnetic resonance (NMR) spectroscopy. 11 The results were similar in a study comparing the metabolome in the same cohort of patients and controls using mass spectrometry, but only plasma levels of valine and isoleucine were significantly increased in patients with ALS. 12 Further, one study used NMR to try to identify a diagnostic profile discriminating 95 patients with motor neuron disease from 86 patients with other neurologic diseases and reported that valine and isoleucine measured in the CSF were among the metabolites contributing most to the final diagnostic model.…”

“…Previous research on BCAAs and ALS risk is sparse, and no study has previously evaluated the association between prediagnostic plasma levels and disease risk. Some, 11,12,25 but not all, 26,27 studies comparing the metabolome in patients with ALS with controls reported alterations in the metabolism of BCAAs in patients. In a study comparing the metabolome in 22 patients with ALS with 28 controls with other neurologic conditions, the plasma levels of all 3 BCAAs were higher in patients with ALS compared to controls in analyses using nuclear magnetic resonance (NMR) spectroscopy.…”

“…9,10 Whether BCAAs increase the risk of ALS is currently not known. Higher levels have been reported in patients with ALS compared to controls, 11,12 but as the amino acids' concentrations may have been affected by the disease itself, it is unclear whether they are etiologically relevant. Prospective studies including prediagnostic samples from individuals later developing ALS could be more informative, but they are difficult to conduct due to the low incidence of the disease.…”

Cerebrospinal and blood levels of amino acids as potential biomarkers for Parkinson’s disease: review and meta‐analysis

“…Six studies did not measure the absolute concentration of amino acids but the relative quantification of many metabolites in individual samples or different groups of samples [3,[6][7][8]10,13]. In another study, CSF absolute concentrations of amino acids were given, but not those of plasma, and therefore it was excluded from the meta-analysis of plasma amino acid levels [5]. Finally, another two studies [4,39] were excluded totally or partially because the results of several amino acids overlapped with the results of other studies of the same group (details in Table S1) [5,40,44] A total of 19 studies reported results of CSF concentrations of at least one amino acid [5,[16][17][18][19][20][22][23][24]26,27,[29][30][31][32][33][34]37,38], and another 18 studies of serum or plasma concentrations of at least one amino acid, in PD patients and controls [11,12,14,16,18,28,[31][32][33]35,36,[39][40]…”

“…Classical studies addressing CSF and serum/plasma concentrations of amino acids in PD patients have been largely inconclusive and have shown high variability, which may be related with several factors such as sample size, differences in the handling and storage of samples or in the study methodologies, the lack of a control group or adequate matching between PD patients and controls, and differences in antiparkinsonian therapies [1]. In recent years, there has been an increasing interest in the potential of proteomics/metabolomics multi-analyte profiles both in CSF [3][4][5][6] and/or in serum/plasma [3,[5][6][7][8][9][10][11][12][13][14] to discriminate PD patients from controls.…”