Dysregulation of energy homeostasis in amyotrophic lateral sclerosis

The role of adiponectin-AMPK axis in TDP-43 mislocalization and disease severity in ALS

Hypermetabolism is a prominent characteristic of ALS patients. Aberrant activation of AMPK, an energy sensor regulated by adiponectin, is known to cause TDP-43 mislocalization, an early event in ALS pathogenesis. This study aims to evaluate the association between key energy mediators and clinical severity in ALS patients. We found that plasma adiponectin levels were significantly higher in ALS patients with ALSFRS-R scores below 38 compared to controls (p = 0.047). Additionally, adiponectin concentration was inversely correlated with ALSFRS-R scores (p = 0.021). Immunofluorescence staining of PBMCs revealed negative associations between AMPK activation, TDP-43 mislocalization, and ALSFRS-R scores. We then examined the hypothesis that adiponectin may activate the AMPK-TDP-43 axis in motor neurons. Our results demonstrated that adiponectin treatment of NSC34 cells and HiPSC-MNs induced AMPK activation and TDP-43 mislocalization in an adiponectin receptor-dependent manner. Collectively, these findings suggest that elevated plasma adiponectin may enhance AMPK activation, leading to TDP-43 mislocalization in both PBMCs and motor neurons of ALS patients. This highlights the potential involvement of the adiponectin-AMPK-TDP-43 axis in the dysregulated energy balance observed in ALS.

Association Between Hypothalamic Volume and Metabolism, Cognition, and Behavior in Patients With Amyotrophic Lateral Sclerosis

BACKGROUND AND OBJECTIVES

Dysfunction of energy metabolism, cognition, and behavior are important nonmotor symptoms of amyotrophic lateral sclerosis (ALS), negatively affecting survival and quality of life, but poorly understood. Neuroimaging is ideally suited to studying nonmotor neurodegeneration in ALS, but few studies have focused on the hypothalamus, a key region for regulating energy homeostasis, cognition, and behavior. We evaluated, therefore, hypothalamic neurodegeneration in ALS and explored the relationship between hypothalamic volumes and dysregulation of energy metabolism, cognitive and behavioral changes, disease progression, and survival.

METHODS

Patients with ALS and population-based controls were included for this cross-sectional and longitudinal MRI study. The hypothalamus was segmented into 5 subregions and their volumes were calculated. Linear (mixed) models, adjusted for age, sex, and total intracranial volume, were used to compare hypothalamic volumes between groups and to analyze associations with metabolism, cognition, behavior, and disease progression. Cox proportional hazard models were used to investigate the relationship of hypothalamic volumes with survival. Permutation-based corrections for multiple hypothesis testing were applied to all analyses to control the family-wise error rate.

RESULTS

Data were available for 564 patients with ALS and 356 controls. The volume of the anterior superior subregion of the hypothalamus was smaller in patients with ALS than in controls (β = -0.70 [-1.15 to -0.25], p = 0.013). Weight loss, memory impairments, and behavioral disinhibition were associated with a smaller posterior hypothalamus (β = -4.79 [-8.39 to -2.49], p = 0.001, β = -10.14 [-15.88 to -4.39], p = 0.004, and β = -12.09 [-18.83 to -5.35], p = 0.003, respectively). Furthermore, the volume of this subregion decreased faster over time in patients than in controls (β = -0.25 [0.42 to -0.09], p = 0.013), and a smaller volume of this structure was correlated with shorter survival (hazard ratio = 0.36 [0.21-0.61], p = 0.029).

DISCUSSION

We obtained evidence for hypothalamic involvement in ALS, specifically marked by atrophy of the anterior superior subregion. Moreover, we found that atrophy of the posterior hypothalamus was associated with weight loss, memory dysfunction, behavioral disinhibition, and survival, and that this subregion deteriorated faster in patients with ALS than in controls. These findings improve our understanding of nonmotor involvement in ALS and could contribute to the identification of new treatment targets for this devastating disease.

ALSUntangled #72: Insulin

ALSUntangled reviews alternative and off-label treatments for people living with amyotrophic lateral sclerosis (PALS). Here we review insulin, which has at least one plausible mechanism for slowing ALS progression. However, pre-clinical studies are limited and there have been no trials in PALS yet. Insulin use in patients without a metabolic need may cause very serious and potentially lethal side effects. While further studies to evaluate potential benefits may be warranted, at this time we cannot endorse insulin treatment to slow ALS progression.

The cytosolic DNA-sensing cGAS-STING pathway in neurodegenerative diseases

BACKGROUND

With the widespread prevalence of neurodegenerative diseases (NDs) and high rates of mortality and disability, it is imminent to find accurate targets for intervention. There is growing evidence that neuroimmunity is pivotal in the pathology of NDs and that interventions targeting neuroimmunity hold great promise. Exogenous or dislocated nucleic acids activate the cytosolic DNA sensor cyclic GMP-AMP synthase (cGAS), activating the stimulator of interferon genes (STING). The activated STING triggers innate immune responses and then the cGAS-STING signaling pathway links abnormal nucleic acid sensing to the immune response. Recently, numerous studies have shown that neuroinflammation regulated by cGAS-STING signaling plays an essential role in NDs.

AIMS

In this review, we summarized the mechanism of cGAS-STING signaling in NDs and focused on inhibitors targeting cGAS-STING.

CONCLUSION

The cGAS-STING signaling plays an important role in the pathogenesis of NDs. Inhibiting the cGAS-STING signaling may provide new measures in the treatment of NDs.

Time-restricted ketogenic diet in amyotrophic lateral sclerosis: a case study

Amyotrophic lateral sclerosis (ALS) is an incurable neurodegenerative disorder. The most devastating variant is bulbar-onset ALS, which portends a median survival of 24 months from the onset of symptoms. Abundant evidence indicates that neuron metabolism and mitochondrial function are impaired in ALS. Metabolic strategies, particularly fasting and ketogenic diet protocols, alter neuron metabolism and mitochondria function in a manner that may mitigate the symptoms of this disorder. We report the case of a 64-year-old man with a 21-month history of progressive, deteriorating bulbar-onset ALS, with an associated pseudobulbar affect, who implemented a time-restricted ketogenic diet (TRKD) for 18 months. During this time, he improved in ALS-related function (7% improvement from baseline), forced expiratory volume (17% improvement), forced vital capacity (13% improvement), depression (normalized), stress levels (normalized), and quality of life (19% improvement), particularly fatigue (23% improvement). His swallowing impairment and neurocognitive status remained stable. Declines were measured in physical function, maximal inspiratory pressure, and maximal expiratory pressure. Weight loss was attenuated and no significant adverse effects occurred. This case study represents the first documented occurrence of a patient with ALS managed with either a fasting or ketogenic diet protocol, co-administered as a TRKD. We measured improved or stabilized ALS-related function, forced expiratory volume, forced vital capacity, swallowing, neurocognitive status, mood, and quality of life. Measurable declines were restricted to physical function, maximal inspiratory pressure, and maximal expiratory pressure. Now over 45 months since symptom onset, our patient remains functionally independent and dedicated to his TRKD.

Amyotrophic Lateral Sclerosis Mechanism: Insights from the Caenorhabditis elegans Models

Amyotrophic Lateral Sclerosis (ALS) is a debilitating neurodegenerative condition characterized by the progressive degeneration of motor neurons. Despite extensive research in various model animals, the cellular signal mechanisms of ALS remain elusive, impeding the development of efficacious treatments. Among these models, a well-characterized and diminutive organism, Caenorhabditis elegans (C. elegans), has emerged as a potent tool for investigating the molecular and cellular dimensions of ALS pathogenesis. This review summarizes the contributions of C. elegans models to our comprehension of ALS, emphasizing pivotal findings pertaining to genetics, protein aggregation, cellular pathways, and potential therapeutic strategies. We analyze both the merits and constraints of the C. elegans system in the realm of ALS research and point towards future investigations that could bridge the chasm between C. elegans foundational discoveries and clinical applications.

AI-assisted quantification of hypothalamic atrophy in amyotrophic lateral sclerosis by convolutional neural network-based automatic segmentation

The hypothalamus is a small structure of the brain with an essential role in metabolic homeostasis, sleep regulation, and body temperature control. Some neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS) and dementia syndromes are reported to be related to hypothalamic volume alterations. Despite its crucial role in human body regulation, neuroimaging studies of this structure are rather scarce due to work-intensive operator-dependent manual delineations from MRI and lack of automated segmentation tools. In this study we present a fully automatic approach based on deep convolutional neural networks (CNN) for hypothalamic segmentation and volume quantification. We applied CNN of U-Net architecture with EfficientNetB0 backbone to allow for accurate automatic hypothalamic segmentation in seconds on a GPU. We further applied our approach for the quantification of the normalized hypothalamic volumes to a large neuroimaging dataset of 432 ALS patients and 112 healthy controls (without the ground truth labels). Using the automated volumetric analysis, we could reproduce hypothalamic atrophy findings associated with ALS by detecting significant volume differences between ALS patients and controls at the group level. In conclusion, a fast and unbiased AI-assisted hypothalamic quantification method is introduced in this study (whose acceptance rate based on the outlier removal strategy was estimated to be above 95%) and made publicly available for researchers interested in the conduction of hypothalamus studies at a large scale.

Interaction of sex and onset site on the disease trajectory of amyotrophic lateral sclerosis

BACKGROUND

Studies showed the impact of sex and onset site (spinal or bulbar) on disease onset and survival in ALS. However, they mainly result from cross-sectional or survival analysis, and the interaction of sex and onset site on the different proxies of disease trajectory has not been fully investigated.

METHODS

We selected all patients with repeated observations in the PRO-ACT database. We divided them into four groups depending on their sex and onset site. We estimated a multivariate disease progression model, named ALS Course Map, to investigate the combined temporal changes of the four sub-scores of the revised ALS functional rating scale (ALSFRSr), the forced vital capacity (FVC), and the body mass index (BMI). We then compared the progression rate, the estimated age at onset, and the relative progression of the outcomes across each group.

RESULTS

We included 1438 patients from the PRO-ACT database. They were 51% men with spinal onset, 12% men with bulbar onset, 26% women with spinal onset, and 11% women with bulbar onset. We showed a significant influence of both sex and onset site on the ALSFRSr progression. The BMI decreased 8.9 months earlier (95% CI [3.9, 13.8]) in women than men, after correction for the onset site. Among patients with bulbar onset, FVC was impaired 2.6 months earlier (95% CI [0.6, 4.6]) in women.

CONCLUSION

Using a multivariable disease modelling approach, we showed that sex and onset site are important drivers of the progression of motor function, BMI, and FVC decline.

Cystatin C based estimation of chronic kidney disease and amyotrophic lateral sclerosis in the ALS registry Swabia: associated risk and prognostic value

Kidney function as part of metabolic changes could be associated with amyotrophic lateral-sclerosis (ALS). We investigated the associations between estimated chronic kidney disease (CKD), based on the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) cystatin C equation, and the risk at onset and prognostic value of CKD for ALS. Between October 2010 and June 2014, 362 ALS cases (59.4% men, mean age 65.7 years) and 681 controls (59.5% men, means age 66.3 years) were included in a population-based case-control study based on the ALS registry Swabia in Southern Germany. All ALS cases were followed-up (median 89.7 months), 317 died. Serum samples were measured for cystatin C to estimate the glomerular filtration rate (eGFR) according to the CKD-EPI equation. Information on covariates were assessed by an interview-based standardized questionnaire. Conditional logistic regression models were applied to calculate odds ratios (OR) for risk of ALS associated with eGFR/CKD stages. Time-to-death associated with renal parameters at baseline was assessed in ALS cases only. ALS cases were characterized by lower body mass index, slightly lower smoking prevalence, more intense occupational work and lower education than controls. Median serum cystatin-C based eGFR concentrations were lower in ALS cases than in controls (54.0 vs. 59.5 mL/min pro 1.73 m2). The prevalence of CKD stage ≥ 3 was slightly higher in ALS cases than in controls (14.1 vs. 11.0%). In the adjusted models, CKD stage 2 (OR 1.82, 95% CI 1.32, 2.52) and stage 3 (OR 2.34, 95% CI 1.38, 3.96) were associated with increased ALS risk. In this cohort of ALS cases, eGFR and CKD stage ≥ 3 (HR 0.94; 95% CI 0.64, 1.38) were not associated with prognosis. In this case-control study, higher CKD stages were associated with increased ALS risk, while in the prospective cohort of ALS cases, no indication of an association of CysC-based CKD on mortality was seen. In addition, our work strengthens the importance to evaluate renal function using a marker independent of muscle mass in ALS patients.

Molecular and Physiological Determinants of Amyotrophic Lateral Sclerosis: What the DJ-1 Protein Teaches Us

Amyotrophic lateral sclerosis (ALS) is an adult-onset disease which causes the progressive degeneration of cortical and spinal motoneurons, leading to death a few years after the first symptom onset. ALS is mainly a sporadic disorder, and its causative mechanisms are mostly unclear. About 5-10% of cases have a genetic inheritance, and the study of ALS-associated genes has been fundamental in defining the pathological pathways likely also involved in the sporadic forms of the disease. Mutations affecting the DJ-1 gene appear to explain a subset of familial ALS forms. DJ-1 is involved in multiple molecular mechanisms, acting primarily as a protective agent against oxidative stress. Here, we focus on the involvement of DJ-1 in interconnected cellular functions related to mitochondrial homeostasis, reactive oxygen species (ROS) levels, energy metabolism, and hypoxia response, in both physiological and pathological conditions. We discuss the possibility that impairments in one of these pathways may affect the others, contributing to a pathological background in which additional environmental or genetic factors may act in favor of the onset and/or progression of ALS. These pathways may represent potential therapeutic targets to reduce the likelihood of developing ALS and/or slow disease progression.

Association Between Serum Lipids and Survival in Patients With Amyotrophic Lateral Sclerosis: A Meta-analysis and Population-Based Study

BACKGROUND AND OBJECTIVE

To explore the association between lipids, polygenic profile scores (PPS) for biomarkers of lipid metabolism, markers of disease severity, and survival in patients with amyotrophic lateral sclerosis (ALS).

METHODS

We meta-analyzed the current literature on the prognostic value of lipids in patients with ALS. Subsequently, we evaluated the relationship between lipid levels at diagnosis, clinical disease stage, and survival in all consecutive patients diagnosed in the Netherlands. We determined the hazard ratio (HR) of each lipid for overall survival, defined as death from any cause. A subset of patients was matched to a previous genome-wide association study; data were used to calculate PPS for biomarkers of lipid metabolism and to determine the association between observed lipid levels at diagnosis and survival.

RESULTS

Meta-analysis of 4 studies indicated that none of the biomarkers of the lipid metabolism were statistically significantly associated with overall survival; there was, however, considerable heterogeneity between study results. Using individual patient data (N = 1,324), we found that increased high-density lipoprotein (HDL) cholesterol was associated with poorer survival (HR of 1.33 (95% CI 1.14-1.55, p < 0.001)). The correlation between BMI and HDL cholesterol (Pearson r -0.26, 95% CI -0.32 to -0.20) was negative and between BMI and triglycerides (TG) positive (Pearson r 0.18, 95% CI 0.12-0.24). Serum concentrations of total cholesterol and LDL cholesterol were lower in more advanced clinical stages (both p < 0.001). PPS for biomarkers of lipid metabolism explained 1.2%-13.1% of their variance at diagnosis. None of the PPS was significantly associated with survival (all p > 0.50).

DISCUSSION

Lipids may contain valuable information about disease severity and prognosis, but their main value may be driven as a consequence of disease progression. Our results underscore that gaining further insight into lipid metabolism and longitudinal data on serum concentrations of the lipid profile could improve the monitoring of patients and potentially further disentangle ALS pathogenesis.

Amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis is a fatal CNS neurodegenerative disease. Despite intensive research, current management of amyotrophic lateral sclerosis remains suboptimal from diagnosis to prognosis. Recognition of the phenotypic heterogeneity of amyotrophic lateral sclerosis, global CNS dysfunction, genetic architecture, and development of novel diagnostic criteria is clarifying the spectrum of clinical presentation and facilitating diagnosis. Insights into the pathophysiology of amyotrophic lateral sclerosis, identification of disease biomarkers and modifiable risks, along with new predictive models, scales, and scoring systems, and a clinical trial pipeline of mechanism-based therapies, are changing the prognostic landscape. Although most recent advances have yet to translate into patient benefit, the idea of amyotrophic lateral sclerosis as a complex syndrome is already having tangible effects in the clinic. This Seminar will outline these insights and discuss the status of the management of amyotrophic lateral sclerosis for the general neurologist, along with future prospects that could improve care and outcomes for patients with amyotrophic lateral sclerosis.

ALSUntangled #64: butyrates

ALSUntangled reviews alternative and off-label treatments for people living with amyotrophic lateral sclerosis (PALS). Here we review butyrate and its different chemical forms (butyrates). Butyrates have plausible mechanisms for slowing ALS progression and positive pre-clinical studies. One trial suggests that sodium phenylbutyrate (NaPB) in combination with Tauroursodeoxycholic acid (TUDCA) can slow ALS progression and prolong survival, but the specific contribution of NaPB toward this effect is unclear. Butyrates appear reasonably safe for use in humans. Based on the above information, we support a trial of a butyrate in PALS, but we cannot yet recommend one as a treatment.