Abnormalities of lipoprotein and carbohydrate metabolism in degenerative diseases of the nervous system--motor neuron disease and spinocerebellar degeneration

Mutation-specific metabolic profiles in presymptomatic amyotrophic lateral sclerosis

BACKGROUND AND PURPOSE

Growing evidence shows that ALS patients feature a disturbed energy metabolism. However, these features have rarely been investigated in the presymptomatic stage.

METHODS

A total of 60 presymptomatic ALS mutation carriers and 70 age- and gender-matched controls (non-mutation carriers from the same families) were recruited. All subjects underwent assessments of their metabolic profiles under fasting conditions at enrollment, including body mass index (BMI), blood pressure and serum levels of blood glucose, total cholesterol, triglycerides, high-density lipoprotein (HDL) and low-density lipoprotein.

RESULTS

All mutations combined, no differences between presymptomatic ALS gene carriers and controls were found. From a cardiovascular point of view, presymptomatic chromosome 9 open reading frame 72 (C9ORF72) gene carriers showed lower cardiovascular risk profiles compared to healthy controls, including lower BMI (median 22.9, interquartile range [IQR] 20.6-26.1 kg/m² vs. 24.9, IQR 22.7-30.5 kg/m² ; p = 0.007), lower systolic blood pressure (120, IQR 110-130 mmHg vs. 128, IQR 120-140 mmHg; p = 0.02), lower fasting serum glucose (89.0, IQR 85.0-97.0 mg/dl vs. 96.0, IQR 89.3-102.0 mg/dl; p = 0.005) and higher HDL (1.6, IQR 1.3-1.8 mmol/l vs. 1.2, IQR 1.0-1.4 mmol/l; p = 0.04). However, presymptomatic superoxide dismutase 1 (SOD1) gene mutation carriers showed higher cardiovascular risk profiles compared to healthy controls, including higher BMI (28.0, IQR 26.1-31.5 kg/m² vs. 24.9, IQR 22.7-30.5 kg/m² ; p = 0.02), higher fasting serum glucose (100.0, IQR 94.0-117.0 mg/dl vs. 96.0, IQR 89.3-102.0 mg/dl; p = 0.04) and lower HDL (1.2, IQR 1.0-1.4 mmol/l vs. 1.4, IQR 1.2-1.7 mmol/l; p = 0.01). These features were most prominent in patients carrying SOD1 gene mutations associated with slow disease progression.

CONCLUSIONS

This study identified distinct metabolic profiles in presymptomatic ALS gene carriers, which might be associated with disease progression in the symptomatic phase.

Analysis of routine blood parameters in patients with amyotrophic lateral sclerosis and evaluation of a possible correlation with disease progression—a multicenter study

Objective

Amyotrophic lateral sclerosis (ALS) pathogenesis is still unclear, its course is considerably variable, and prognosis is hard to determine. Despite much research, there is still a lack of easily accessible markers predicting prognosis. We investigated routine blood parameters in ALS patients regarding correlations with disease severity, progression rate, and survival. Additionally, we analyzed disease and patients' characteristics relating to baseline blood parameter levels.

Methods

We analyzed creatine kinase (CK), albumin (ALB), creatinine (CREA), total cholesterol (TC), high-density lipoprotein cholesterol (HDL), low-density lipoprotein cholesterol (LDL), and triglycerides (TG) levels around time of diagnosis in 1,084 ALS patients. We carried out linear regression analyses including disease and patients' characteristics with each blood parameter to detect correlations with them. Linear regression models were performed for ALSFRS-R at study entry, its retrospectively defined rate of decay and prospectively collected progression rate. Different survival analysis methods were used to examine associations between blood parameters and survival.

Results

We found higher CK (p-value 0.001), ALB (p-value <0.001), CREA (p-value <0.001), and HDL levels (p-value 0.044) at time of diagnosis being associated with better functional status according to ALSFRS-R scores at study entry. Additionally, higher CREA levels were associated with lower risk of death (p-value 0.003).

Conclusions

Our results indicate potential of CK, ALB, CREA, and HDL as disease severity or progression markers, and may also provide clues to ALS pathogenesis. However, these values are highly dependent on other variables, and further careful, longitudinal analyses will be necessary to prove the relevance of our findings.

Aberrations of biochemical indicators in amyotrophic lateral sclerosis: a systematic review and meta-analysis

Accumulating evidence has suggested that the pathological changes in amyotrophic lateral sclerosis (ALS) are not only confined to the central nervous system but also occur in the peripheral circulating system. Here, we performed a meta-analysis based on the PubMed, EMBASE, EBSCO, and CNKI databases, to find out biochemical indicators associated with energy metabolism, iron homeostasis, and muscle injury that are altered in ALS patients and their correlations with ALS phenotypes. Forty-six studies covering 17 biochemical indicators, representing 5454 ALS patients and 7986 control subjects, were included in this meta-analysis. Four indicators, including fasting blood glucose level (weighted mean difference [WMD] = 0.13, 95% CI [0.06–0.21], p = 0.001), serum ferritin level (WMD = 63.42, 95% CI [48.12–78.73], p < 0.001), transferrin saturation coefficient level (WMD = 2.79, 95% CI [1.52–4.05], p < 0.001), and creatine kinase level (WMD = 80.29, 95% CI [32.90–127.67], p < 0.001), were significantly higher in the ALS patients, whereas the total iron-binding capacity (WMD = − 2.42, 95% CI [− 3.93, − 0.90], p = 0.002) was significantly lower in ALS patients than in the control subjects. In contrast, the other 12 candidates did not show significant differences between ALS patients and controls. Moreover, pooled hazard ratios (HR) showed significantly reduced survival (HR = 1.38, 95% CI [1.02–1.88], p = 0.039) of ALS patients with elevated serum ferritin levels. These findings suggest that abnormalities in energy metabolism and disruption of iron homeostasis are involved in the pathogenesis of ALS. In addition, the serum ferritin level is negatively associated with the overall survival of ALS patients.

Metabolic Alteration and Amyotrophic Lateral Sclerosis Outcome: A Systematic Review

Background: The development of strategies that could not only efficiently detect the onset of Amyotrophic Lateral Sclerosis (ALS), a fatal neurodegenerative disorder with no cure but also predict its development and evaluate therapeutic intervention would be of great value. In this respect, the metabolic status of ALS patients has called attention. Hence, this study aimed to investigate the potential correlation between changes in ALS's metabolic parameters with the disease outcome in a systematic review. Methods: The manuscripts were manually searched within different databases (PubMed, Web of Science and Cochrane). The inclusion criteria were original articles and reviews about individuals with ALS and its survival, disease prognosis and metabolism (weight, cholesterol, hypertension, BMI, and glycaemia). The authors also established three different exclusion criteria: studies including ALS and other degenerative disorders, works including animal models and published before the year 2000. Results: In total, 29 papers were selected. From all manuscripts, only 82.8% ensured the participation of sALS patients. Also, 27.6% of selected studies described the presence of a genetic mutation. Regarding ALS prognosis, patient's age, the age of ALS onset, ALS duration and survival, <50% of the papers addressed these issues. Specifically, regarding metabolism, 65.5% of articles mentioned BMI, 20.7% mentioned any data concerning hypertension, 6.89% cardiovascular risk, 10.3% obesity, 13.78% diabetes and 10.3% glycaemia. Concerning lipid metabolism, more results were gathered, but still, they did not suffice to establish a correlation with ALS development. Conclusions: Altogether, the authors concluded that available information is not enough to establish a link between ALS and metabolism. In reality, less than half of the manuscripts evaluated show an association between both factors. Nonetheless, it is worth mentioning that metabolism does influence ALS, but not in a unique manner. There is a debate about patients' hypo- and hypermetabolism. Thus, to provide a reliable record, a public policy in which all research and clinical centers might assess the parameters discussed herein is suggested. Accordingly, this systematic review attempts to provide a comprehensible database to facilitate multicentered collaboration, validation, and clinical translation.

Association between macronutrient intake and amyotrophic lateral sclerosis prognosis

Objectives: Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease, and the nutritional state of ALS patients is associated with survival. The purpose of the present study was to investigate whether macronutrient intake at early stage of the disease was positively associated with survival and duration from symptom onset to death, tracheostomy, or non-invasive ventilation (NIV) in ALS.Methods: ALS patients diagnosed according to EI Escorial criteria were recruited from 2011 to 2016 and followed up until 2017, when they reached the endpoint of death, tracheostomy, or NIV use. Dietary intake was estimated based on a 24-hour recall conducted less than 2 years from symptom onset, and the survival time was defined as the duration from symptom onset to the endpoint.Results: ALS patients were categorized as short-term group (n=79) and long-term group (n=69) according to the mean survival time (33.03±14.01 months). Short-term survival was negatively associated with fat, protein, and meat intake, and positively associated with carbohydrate intake after adjustment for confounders. In addition, the survival time was positively associated with fat, protein, and meat intake but was not associated with carbohydrate intake.Discussion: The present study suggested that higher intake of fat and protein, particularly from meat at early stage of the disease, could prolong the survival of ALS patients. However, further clinical trials are necessary to confirm the beneficial effects of higher fat and protein intake on mortality in ALS patients.

Low IDL-B and high LDL-1 subfraction levels in serum of ALS patients

INTRODUCTION

Converging evidence highlights that lipid metabolism plays a key role in ALS pathophysiology. Dyslipidemia has been described in ALS patients and may be protective but peripheral lipoprotein subclasses have never been studied.

MATERIAL AND METHODS

We collected sera from 30 ALS patients and 30 gender and age-matched controls. We analyzed 11 distinct lipoprotein subclasses by linear polyacrylamide gel electrophoresis (Lipoprint, Quantimetrix Corporation, USA). We also measured lipoprotein (a), apolipoprotein B, and apolipoprotein E levels.

RESULTS

ALS patients had significant higher total cholesterol, HDL-cholesterol, and LDL-cholesterol levels than controls (p<0.0001, p=0.0007, and p=0.0065, respectively). The LDL-1 subfraction concentration was higher (1.03±0.41 vs. 0.71±0.28mmol/L; p=0.0006) and the IDL-B subfraction lower (6.5±2% vs. 8.0±2%; p=0.001) in ALS patients than controls.

DISCUSSION

Our preliminary work confirmed the association between ALS and dyslipidemia. The low IDL-B levels may explain the hepatic steatosis frequently reported in ALS. The high levels of the cholesterol-rich LDL-1 subfraction is consistent with previously reported hypercholesterolemia.

CONCLUSION

This study describes, for the first time, the distribution of serum lipoproteins in ALS patients, with low IDL-B and high LDL-1 subfraction level.

Body Mass Index and Amyotrophic Lateral Sclerosis: A Study of US Military Veterans

Amyotrophic lateral sclerosis (ALS) may be associated with low body mass index (BMI) at the time of diagnosis. However, the role of premorbid BMI in the development of ALS and survival after diagnosis remains unclear. In 2005-2010, we interviewed 467 patients with ALS from the US National Registry of Veterans with ALS and 975 frequency-matched veteran controls. In this sample, we evaluated the association of BMI and BMI change at different ages with ALS risk using unconditional logistic models and with survival after ALS diagnosis using Cox proportional hazards models. After adjustment for confounders, compared with a moderate increase in BMI between ages 25 and 40 years, stable or decreasing BMI was positively associated with ALS risk (odds ratio (OR) = 1.61, 95% confidence interval (CI): 1.20, 2.16). A 1-unit increase in BMI at age 40 years (OR = 0.95, 95% CI: 0.91, 0.98) but not at age 25 years (OR = 0.99, 95% CI: 0.95, 1.03) was inversely associated with ALS. These associations were similar for bulbar and spinal ALS but stronger for those with a delay of less than 1 year between symptom onset and diagnosis. We found no association between prediagnosis BMI and survival. A decreasing BMI from early to middle age and a low BMI in middle age may be positively associated with ALS risk.

Combined Metabolomics and Transcriptomics Approaches to Assess the IL-6 Blockade as a Therapeutic of ALS: Deleterious Alteration of Lipid Metabolism

In amyotrophic lateral sclerosis (ALS), motor neuron degeneration occurs simultaneously with systemic metabolic impairment and neuroinflammation. Playing an important role in the regulation of both phenomena, interleukin (IL)-6, a major cytokine of the inflammatory response has been proposed as a target for management of ALS. Although a pilot clinical trial provided promising results in humans, another recent preclinical study showed that knocking out the IL-6 gene in mice carrying ALS did not improve clinical outcome. In this study, we aimed to determine the relevance of the IL-6 pathway blockade in a mouse model of ALS by using a pharmacological antagonist of IL-6, a murine surrogate of tocilizumab, namely MR16-1. We analyzed the immunological and metabolic effects of IL-6 blockade by cytokine measurement, blood cell immunophenotyping, targeted metabolomics, and transcriptomics. A deleterious clinical effect of MR16-1 was revealed, with a speeding up of weight loss (p = 0.0041) and decreasing body weight (p < 0.05). A significant increase in regulatory T-cell count (p = 0.0268) and a decrease in C-X-C ligand-1 concentrations in plasma (p = 0.0479) were observed. Metabolomic and transcriptomic analyses revealed that MR16-1 mainly affected branched-chain amino acid, lipid, arginine, and proline metabolism. IL-6 blockade negatively affected body weight, despite a moderated anti-inflammatory effect. Metabolic effects of IL-6 were mild compared with metabolic disturbances observed in ALS, but a modification of lipid metabolism by therapy was identified. These results indicate that IL-6 blockade did not improve clinical outcome of a mutant superoxide dismutase 1 mouse model of ALS.

AMPK Signalling and Defective Energy Metabolism in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is caused by selective loss of upper and lower motor neurons by complex mechanisms that are incompletely understood. Motor neurons are large, highly polarised and excitable cells with unusually high energetic demands to maintain resting membrane potential and propagate action potentials. This leads to higher ATP consumption and mitochondrial metabolism in motor neurons relative to other cells. Here, we review increasing evidence that defective energy metabolism and homeostasis contributes to selective vulnerability and degeneration of motor neurons in ALS. Firstly, we provide a brief overview of major energetic pathways in the CNS, including glycolysis, oxidative phosphorylation and the AMP-activated protein kinase (AMPK) signalling pathway, while highlighting critical metabolic interactions between neurons and astrocytes. Next, we review evidence from ALS patients and transgenic mutant SOD1 mice for weight loss, hypermetabolism, hyperlipidemia and mitochondrial dysfunction in disease onset and progression. Genetic and therapeutic modifiers of energy metabolism in mutant SOD1 mice will also be summarised. We also present evidence that additional ALS-linked proteins, TDP-43 and FUS, lead to energy disruption and mitochondrial defects in motor neurons. Lastly, we review emerging evidence including our own that dysregulation of the AMPK signalling cascade in motor neurons is an early and common event in ALS pathogenesis. We suggest that an imbalance in energy metabolism should be considered an important factor in both progression and potential treatment of ALS.

Patients with elevated triglyceride and cholesterol serum levels have a prolonged survival in amyotrophic lateral sclerosis

Weight loss is a common phenomenon and an independent prognostic factor in amyotrophic lateral sclerosis (ALS). Several potential causal mechanisms, including intrinsic hypermetabolism and deficient food intake, have been discussed. We investigated the influence of fasting serum glucose, cholesterol, and triglyceride levels at time of diagnosis on survival in ALS. Serum cholesterol (LDL, HDL, and LDL/HDL ratio), triglycerides, and glucose were investigated in 488 patients (age of onset = 57.6 ± 12.6 years) in relation to survival and revised Amyotrophic Lateral Sclerosis Functional Rating Scale (ALS-FRS) data. High serum levels of both fasting cholesterol and triglycerides had a significantly positive effect on survival (p < 0.05). We found a median prolonged life expectancy by 14 months for patients with serum triglyceride levels above the median of 1.47 mmol/l. The results suggest that the lipid metabolism and the nutritional status of ALS patients are important prognostic factors. These parameters should be thoroughly monitored during the clinical management of these patients. In case of progressive loss of body weight, a diet rich in lipids and calories should be considered. However, the final decision whether a lipid-rich diet should be recommended to ALS patients can only be based on a double-blind placebo-controlled interventional trial. Our results further imply that lipid-lowering drugs, e.g., statins, should be applied carefully in ALS patients although individual risk considerations must be made.

Nutritional status and risk of amyotrophic lateral sclerosis in Japan

Only a few human studies have reported the relationship between dietary factors and the risk of amyotrophic lateral sclerosis (ALS). We therefore analyzed the relationship between macronutrients (carbohydrate, protein and fat) and the risk of ALS using a case-control study in Japan. The study comprised 153 ALS patients diagnosed by the El Escorial World Federation of Neurology criteria, and 306 gender- and age- matched controls randomly selected from the general population. A self-administered food frequency questionnaire was used to estimate pre-illness intakes of food groups and nutrients. The strength of association between ALS and a potential risk factor was assessed by calculating odds ratios (ORs) and 95% confidence intervals (CIs). A high intake of carbohydrate was significantly associated with an increased risk of ALS (adjusted OR = 2.14, 95% CI 1.05-4.36; the highest versus the lowest tertile). ORs for the second and third tertile of total fat were 0.57 and 0.41 (95% CI 0.21-0.80), respectively. ORs for the highest tertile of intake versus the lowest were 0.41 (95% CI 0.21-0.80) for total fat, 0.30 (95% CI 0.16-0.5) for saturated fatty acids (SFAs), 0.35 (95% CI 0.18-0.69) for monounsaturated fatty acids (MUFAs) and 0.58 (95%CI 0.40-0.96) for polyunsaturated fatty acids (PUFAs). Our findings suggest that high intakes of carbohydrate and low intakes of fat and some kinds of fatty acids may, when combined, increased the risk of ALS.

The metabolic hypothesis in amyotrophic lateral sclerosis: insights from mutant Cu/Zn-superoxide dismutase mice

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by selective loss of motor neurons and progressive muscle atrophy. A subset of patients harbors point mutations in the gene encoding Cu/Zn-superoxide dismutase (SOD1), which allowed the generation of transgenic mice that express different SOD1 mutations and develop an ALS-like pathology. Recently, we reported in these mice the occurrence of a characteristic defect in energy homeostasis and the beneficial effect on the course of the disease of a high-energy fat-enriched diet. In this review, we discuss the implication of these findings in the light of classical clinical observations concerning metabolic alterations in human ALS.

ALS-linked Cu/Zn-SOD mutation impairs cerebral synaptic glucose and glutamate transport and exacerbates ischemic brain injury

Although degeneration of lower motor neurons is the most striking abnormality in amyotrophic lateral sclerosis (ALS), more subtle alterations may occur in the brain. Mutations in copper/zinc superoxide dismutase (Cu/Zn-SOD) are responsible for some cases of inherited ALS, and expression of mutant Cu/Zn-SOD in transgenic mice results in progressive motor neuron loss and a clinical phenotype similar to that of ALS patients. It is now reported that Cu/Zn-SOD mutant mice exhibit increased vulnerability to focal ischemic brain injury after transient occlusion of the middle cerebral artery. Levels of glucose and glutamate transport in cerebral cortex synaptic terminals were markedly decreased, and levels of membrane lipid peroxidation were increased in Cu/Zn-SOD mutant mice compared to nontransgenic mice. These findings demonstrate that mutant Cu/Zn-SOD may endanger brain neurons by a mechanism involving impairment of glucose and glutamate transporters. Moreover, our data demonstrate a direct adverse effect of the mutant enzyme on synaptic function.

Recombinant growth hormone treatment of amyotrophic lateral sclerosis

Based on the known trophic effects of growth hormone (GH) on nerve and muscle 75 patients with ALS were treated for up to 18 months with synthetic human growth hormone (Protropin) or a placebo. The course of ALS was assessed serially using a quantitative (TQNE) neuromuscular and manual exam (MRC) and laboratory chemistries. Average insulin-related growth factor (IGF-I) values increased from 1.2 to 2.3 U/mL in the treated group. Surprisingly, serum insulin levels did not increase. Hyperglycemia was noted in only 2 patients of the 38 patients receiving hGH, and this resolved with cessation of treatment. Over the 12 months of treatment there were 11 deaths (6 controls, 5 treated). Survival analysis, performed approximately 12 months following cessation of treatment, did not reveal a difference between the treatment and placebo group. The TQNE scores declined inexorably in both the control and treated group. Retrospective analysis of the TQNE data indicated a poor prognosis for patients who lost arm strength early. A correlation between the TQNE and MRC scores was evident at early stages of motor unit loss, less so when muscle weakness was advanced.

Electron spin resonance studies of erythrocyte membrane in spinocerebellar degeneration

Erythrocyte membrane fluidity was examined by electron spin resonance spectra using nitroxide fatty acid spin labels in spinocerebellar degeneration (SCD). Subjects with SCD, motor neuron disease (MND) and controls did not differ in fluidity of the deep site (hydrophobic region) of the erythrocyte membrane. However, the fluidity of the shallow site (hydrophilic region) in the erythrocyte membrane was significantly less fluid in SCD than in controls and MND (outer hyperfine splitting of 5-nitroxide stearic acid: SCD 54.70 +/- 0.43 G, controls 53.57 +/- 0.41 G, MND 53.54 +/- 0.35 G, P less than 0.001). Serum HDL-cholesterol and membrane fluidity correlated significantly in controls, but not in SCD. A significant negative correlation between age and membrane fluidity was found in SCD, but not in controls. These data suggest that membrane abnormality exists in SCD and may be concerned with aging.