Serum ferritin and metal levels as risk factors for amyotrophic lateral sclerosis

Comparative assessment of blood Metal/metalloid levels, clinical heterogeneity, and disease severity in amyotrophic lateral sclerosis patients

Amyotrophic lateral sclerosis is an unremitting neurodegenerative (ND) disease characterized by progressive and fatal loss of motor neuron function. While underlying mechanisms for ALS susceptibility are complex, current understanding suggests that interactions between age, genetic, and environmental factors may be the key. Environmental exposure to metal/metalloids has been implicated in various ND diseases including ALS, Alzheimer's Disease (AD), and Parkinson's Disease (PD). However, most of currently available population-based ALS studies in relation to metal exposure are based on individuals from European ancestry, while East Asian populations, especially cohorts from China, are less well-characterized. This study aims to examine the association between metal/metalloid levels and ALS onset by evaluating blood cadmium (Cd), lead (Pb), Cu, Zn, calcium (Ca), magnesium (Mg), and iron (Fe) levels in controls and sporadic ALS patients from North Western China. We report that Cu and Fe levels are found at higher levels in ALS patients compared to the controls. Spinal and bulbar onset patients show significant difference in Ca levels. Moreover, Cd, Pb, Cu, and Ca levels are positively correlated with high disease severity. Results from this study may provide new insights for understanding not only the role of metal/metalloids in ALS susceptibility, but also progression and forms of onset.

Whole and fractionated human platelet lysate biomaterials-based biotherapy induces strong neuroprotection in experimental models of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease of motor neurons leading to death within 3 years and without a curative treatment. Neurotrophic growth factors (NTFs) are pivotal for cell survival. A reason for the lack of patient efficacy with single recombinant NTF brain infusion is likely to be due to the synergistic neuroprotective action of multiple NTFs on a diverse set of signaling pathways. Fractionated (protein size <50, <30, <10, <3 kDa) heat-treated human platelet lysate (HHPL) preparations were adapted for use in brain tissue with the aim of demonstrating therapeutic value in ALS models and further elucidation of the mechanisms of action. In neuronal culture all fractions induced Akt-dependent neuroprotection as well as a strong anti-apoptotic and anti-ferroptotic action. In the <3 kDa fraction anti-ferroptotic properties were shown to be GPX4 dependent highlighting a role for other platelet elements associated with NTFs. In the SOD1^G86R mouse model, lifespan was strongly increased by intracerebroventricular delivery of HHPL or by intranasal administration of <3 kDa fraction. Our results suggest that the platelet lysate biomaterials are neuroprotective in ALS. Further studies would now validate theragnostic biomarker on its antiferroptotic action, for further clinical development.

Alterations of the serum and CSF ferritin levels and the diagnosis and prognosis of amyotrophic lateral sclerosis

Background

The ALS diagnostic challenges necessitate more robust diagnostic and prognostic methods. A potential biomarker in this regard is the alterations of ferritin levels in the serum and CSF of patients compared to controls.

Methods

The CSF and serum ferritin levels were measured in 50 ALS cases and 50 control patients with predefined exclusion criteria. The ELISA method was utilized for laboratory measurement and was statistically analyzed using the SPSS.

Results

Heightened serum ferritin levels in cases were not statistically significant. However, CSF ferritin levels were significantly higher in ALS patients (P < 0.001). Serum ferritin levels were significantly negatively correlated with the disease duration (P = 0.015) and were significantly positively correlated with the disease progression rate (DPR) (P = 0.012).

Conclusion

Heightened CSF ferritin levels can be used for the diagnosis of ALS. The correlation between the serum ferritin levels with the DPR and its correlation with the disease duration suggests potential prognostic utilities.

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Elevated serum ferritin level in patients with ALS is insignificant.

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CSF ferritin levels are significantly higher in ALS patients.

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Serum ferritin levels are negatively correlated with the disease duration.

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Serum ferritin levels are positively correlated with the disease progression rate.

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.

Astrocytes in heavy metal neurotoxicity and neurodegeneration

With the industrial development and progressive increase in environmental pollution, the mankind overexposure to heavy metals emerges as a pressing public health issue. Excessive intake of heavy metals, such as arsenic (As), manganese (Mn), mercury (Hg), aluminium (Al), lead (Pb), nickel (Ni), bismuth (Bi), cadmium (Cd), copper (Cu), zinc (Zn), and iron (Fe), is neurotoxic and it promotes neurodegeneration. Astrocytes are primary homeostatic cells in the central nervous system. They protect neurons against all types of insults, in particular by accumulating heavy metals. However, this makes astrocytes the main target for heavy metals neurotoxicity. Intake of heavy metals affects astroglial homeostatic and neuroprotective cascades including glutamate/GABA-glutamine shuttle, antioxidative machinery and energy metabolism. Deficits in these astroglial pathways facilitate or even instigate neurodegeneration. In this review, we provide a concise outlook on heavy metal-induced astrogliopathies and their association with major neurodegenerative disorders. In particular, we focus on astroglial mechanisms of iron-induced neurotoxicity. Iron deposits in the brain are detected in main neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis. Accumulation of iron in the brain is associated with motor and cognitive impairments and iron-induced histopathological manifestations may be considered as the potential diagnostic biomarker of neurodegenerative diseases. Effective management of heavy metal neurotoxicity can be regarded as a potential strategy to prevent or retard neurodegenerative pathologies.

Iron-responsive-like elements and neurodegenerative ferroptosis

A set of common-acting iron-responsive 5′untranslated region (5′UTR) motifs can fold into RNA stem loops that appear significant to the biology of cognitive declines of Parkinson's disease dementia (PDD), Lewy body dementia (LDD), and Alzheimer's disease (AD). Neurodegenerative diseases exhibit perturbations of iron homeostasis in defined brain subregions over characteristic time intervals of progression. While misfolding of Aβ from the amyloid-precursor-protein (APP), alpha-synuclein, prion protein (PrP) each cause neuropathic protein inclusions in the brain subregions, iron-responsive-like element (IRE-like) RNA stem–loops reside in their transcripts. APP and αsyn have a role in iron transport while gene duplications elevate the expression of their products to cause rare familial cases of AD and PDD. Of note, IRE-like sequences are responsive to excesses of brain iron in a potential feedback loop to accelerate neuronal ferroptosis and cognitive declines as well as amyloidosis. This pathogenic feedback is consistent with the translational control of the iron storage protein ferritin. We discuss how the IRE-like RNA motifs in the 5′UTRs of APP, alpha-synuclein and PrP mRNAs represent uniquely folded drug targets for therapies to prevent perturbed iron homeostasis that accelerates AD, PD, PD dementia (PDD) and Lewy body dementia, thus preventing cognitive deficits. Inhibition of alpha-synuclein translation is an option to block manganese toxicity associated with early childhood cognitive problems and manganism while Pb toxicity is epigenetically associated with attention deficit and later-stage AD. Pathologies of heavy metal toxicity centered on an embargo of iron export may be treated with activators of APP and ferritin and inhibitors of alpha-synuclein translation.

Abnormal Serum Iron-Status Indicator Changes in Amyotrophic Lateral Sclerosis (ALS) Patients: A Meta-Analysis

Background: In recent years, the role of iron metabolism in amyotrophic lateral sclerosis (ALS) attracts more and more attention, and some studies have focused on the link between abnormal serum iron indicators and ALS. However, there are still big conflicts and inconsistency among different studies. To study the possible relationship between ALS and disturbed iron metabolism, we conducted this meta-analysis to conclude characteristics of abnormal serum iron-status indicator changes in ALS patients.

Methods: We searched and screened main databases, including the PubMed, Embase, and Cochrane Library, to find studies related to the association between iron metabolism and ALS. The Revman 5.3 software was used to conduct meta-analysis.

Results: Eleven studies were finally included in our analysis, composed of 1,599 ALS patients and 1,255 controls in total. The results showed that the ferritin level was much higher in ALS patients compared with controls (MD = 70.48, 95% CI [51.41, 89.55], p < 0.00001), and the transferrin level was decreased in ALS patients compared with controls (SMD = −0.28, 95% CI [−0.38, −0.18], p < 0.00001), while there was no statistical difference in iron levels (SMD = 0.48, 95% CI [−0.07, 1.03], p = 0.09) between ALS patients and controls.

Conclusions: Our research finds unusual changes in several indicators representing iron status, which suggest possible iron metabolism abnormalities in ALS patients. That may provide evidence for the link between iron metabolism and the pathogenesis of ALS.

Mitophagy and iron: two actors sharing the stage in age-associated neuronal pathologies

Aging is characterized by the deterioration of different cellular and organismal structures and functions. A typical hallmark of the aging process is the accumulation of dysfunctional mitochondria and excess iron, leading to a vicious cycle that promotes cell and tissue damage, which ultimately contribute to organismal aging. Accordingly, altered mitochondrial quality control pathways such as mitochondrial autophagy (mitophagy) as well as altered iron homeostasis, with consequent iron overload, can accelerate the aging process and the development and progression of different age-associated disorders. In this review we first briefly introduce the aging process and summarize molecular mechanisms regulating mitophagy and iron homeostasis. We then provide an overview on how dysfunction of these two processes impact on aging and age-associated neurodegenerative disorders with a focus on Alzheimer's disease, Parkinson's disease and Amyotrophic Lateral Sclerosis. Finally, we summarize some recent evidence showing mechanistic links between iron metabolism and mitophagy and speculate on how regulating the crosstalk between the two processes may provide protective effects against aging and age-associated neuronal pathologies.

Redox active metals in neurodegenerative diseases

Copper (Cu) and iron (Fe) are redox active metals essential for the regulation of cellular pathways that are fundamental for brain function, including neurotransmitter synthesis and release, neurotransmission, and protein turnover. Cu and Fe are tightly regulated by sophisticated homeostatic systems that tune the levels and localization of these redox active metals. The regulation of Cu and Fe necessitates their coordination to small organic molecules and metal chaperone proteins that restrict their reactions to specific protein centres, where Cu and Fe cycle between reduced (Fe²⁺, Cu⁺) and oxidised states (Fe³⁺, Cu²⁺). Perturbation of this regulation is evident in the brain affected by neurodegeneration. Here we review the evidence that links Cu and Fe dyshomeostasis to neurodegeneration as well as the promising preclinical and clinical studies reporting pharmacological intervention to remedy Cu and Fe abnormalities in the treatment of Alzheimer's disease (AD), Parkinson's disease (PD) and Amyotrophic lateral sclerosis (ALS).

Iron Metabolism of the Skeletal Muscle and Neurodegeneration

Recent studies clearly indicate that the endocrine function of the skeletal muscle is essential for a long and healthy life. Regular exercise, which has been shown to stimulate the release of myokines, lowers the risk of many diseases, including Alzheimer’s and Parkinson’s disease, emphasizing the role of skeletal muscle in proper functioning of other tissues. In addition, exercise increases insulin sensitivity, which may also impact iron metabolism. Even though the role of iron in neurodegeneration is well established, the exact mechanisms of iron toxicity are not known. Interestingly, exercise has been shown to modulate iron metabolism, mainly by reducing body iron stores. Insulin signaling and iron metabolism are interconnected, as high tissue iron stores are associated with insulin resistance, and conversely, impaired insulin signaling may lead to iron accumulation in an affected tissue. Excess iron accumulation in tissue triggers iron-dependent oxidative stress. Further, iron overload in the skeletal muscle not only negatively affects muscle contractility but also might impact its endocrine function, thus possibly affecting the clinical outcome of diseases, including neurodegenerative diseases. In this review, we discuss possible mechanisms of iron dependent oxidative stress in skeletal muscle, its impact on muscle mass and endocrine function, as well as on neurodegeneration processes.

Diagnostic Challenge and Neuromuscular Junction Contribution to ALS Pathogenesis

Amyotrophic lateral sclerosis (ALS) represents the major adult-onset motor neuron disease. Both human and animal studies reveal the critical implication of muscle and neuromuscular junctions (NMJs) in the initial phase of this disease. Despite the common efforts, ALS diagnosis remains particularly challenging since many other disorders can overlap yielding similar clinical phenotypic features. A combination of further research on the NMJ parameters that are specific for this disease and laboratory tests are crucial for the early determination of specific changes in the muscle, as well as in motor neuron and the prediction of ALS progression. Also, it could provide a powerful tool in the discrimination of particular ALS and ALS-mimic cases and increase the efficacy of therapeutic treatments.

Elevated serum ferritin level as a predictor of reduced survival in patients with sporadic amyotrophic lateral sclerosis in China: a retrospective study

Objective: The objective of this study was to compare iron metabolic variables in the serum and cerebrospinal fluid (CSF) of patients with sporadic amyotrophic lateral sclerosis (sALS) with those of patients with multiple system atrophy (MSA) and control subjects. We also assessed the correlations of these variables with sALS progression and severity and estimated their roles in predicting prognosis. Methods: We retrospectively collected iron metabolic parameters, including serum levels of iron, ferritin, transferrin levels and total iron binding capacity and the CSF level of ferritin, from 435 sALS patients, 176 MSA patients and 431 control subjects. Results: Serum ferritin levels were significantly higher in the sALS group compared with the MSA and control groups in both males (p = 0.001 and p < 0.0001, respectively) and females (p = 0.034 and p < 0.0001, respectively). However, serum transferrin levels were significantly lower in females of the sALS group compared with the MSA (p = 0.016) and control (p = 0.015) groups. The CSF ferritin level and the serum levels of total iron binding capacity and iron were similar among the sALS, MSA and control groups. Survival analysis demonstrated that higher serum ferritin levels were predictors of reduced survival of sALS patients. No correlations between iron metabolic variables and clinical parameters were found. Conclusion: An elevated serum ferritin level is associated with reduced survival of sALS patients. However, the levels of iron metabolic parameters were not associated with clinical deterioration or disease severity at diagnosis.

The Relevancy of Data Regarding the Metabolism of Iron to Our Understanding of Deregulated Mechanisms in ALS; Hypotheses and Pitfalls

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease caused by the loss of motor neurons. Its etiology remains unknown, but several pathophysiological mechanisms are beginning to explain motor neuronal death, as well as oxidative stress. Iron accumulation has been observed in both sporadic and familial forms of ALS, including mouse models. Therefore, the dysregulation of iron metabolism could play a role in the pathological oxidative stress in ALS. Several studies have been undertaken to describe iron-related metabolic markers, in most cases focusing on metabolites in the bloodstream due to few available data in the central nervous system. Reports of accumulation of iron, high serum ferritin, and low serum transferrin levels in ALS patients have encouraged researchers to consider dysregulated iron metabolism as an integral part of ALS pathophysiology. However, it appears complicated to suggest a general mechanism due to the diversity of models and iron markers studied, including the lack of consensus among all of the studies. Regarding clinical study reports, most of them do not take into account confusion biases such as inflammation, renal dysfunction, and nutritional status. Furthermore, the iron regulatory pathways, particularly involving hepcidin, have not been thoroughly explored yet within the pathogenesis of iron overload in ALS. In this sense, it is also essential to explore the relation between iron overload and other ALS-related events, such as neuro-inflammation, protein aggregation, and iron-driven cell death, termed ferroptosis. In this review, we point out limits of the designs of certain studies that may prevent the understanding of the role of iron in ALS and discuss the relevance of the published data regarding the pathogenic impact of iron metabolism deregulation in this disease and the therapeutics targeting this pathway.

The Role of Iron in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder characterized by the degeneration of motor neurons in the motor cortex, brainstem, and spinal cord. The etiology and pathogenesis of this devastating disease remain largely unknown. Increasing evidence suggests that iron accumulation is involved in the onset and progression of ALS. In this review, we discuss the regulation of iron homoeostasis in the brain, the misregulation of iron homeostasis in ALS, and its possible roles in the mechanism of the disease. Finally, we summarize the recent progress and problems with respect to iron chelator therapies on ALS, aiming to propose a new therapeutic strategy to ameliorate the progression of the disease.

Meta-analysis of the relationship between amyotrophic lateral sclerosis and susceptibility to serum ferritin level elevation

Objective:

To study the possible relationship between amyotrophic lateral sclerosis (ALS) patients and their susceptibility to serum ferritin level elevation.

Methods:

We searched the PubMed, Springer, Medline, and OVID databases for any-language original research articles relating to serum ferritin levels in ALS patients published between June 2005 and June 2015. The search term used with ‘amyotrophic lateral sclerosis’, ‘ferritins’, ‘ferritin’, ‘iron’, ‘iron stores, ‘iron status, ‘iron intake’, and ‘iron consumption’. The meta-analysis software RevMan 5.0 was used for the heterogeneity test, and to test for the overall effect.

Results:

Six case-control studies met our inclusion criteria including data from a total of 1813 participants. The mean difference of serum ferritin levels comparing ALS to healthy controls was 69.05 (95% confidence interval: 52.56-85.54; p<0.00001); heterogeneity: p=0.03; I²=50%. The findings indicate homology in the sensitivity analysis. Funnel plot assessment indicated publication bias.

Conclusion:

Our results suggest that ALS is positively associated with susceptibility to the elevation of serum ferritin levels; however, further evidence is required to support this.

Serum ferritin is a candidate biomarker of disease aggravation in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease. The mechanism that defines the loss of neurons in ALS is still not clearly understood, and there is no effective therapy to block its progression. Previous studies indicate that a disorder of iron homeostasis exists in ALS and based on this, the change of serum iron and ferritin and the association between iron metabolism and clinical features in Chinese Han patients with ALS was further investigated in the present study, in order to define its pathogenesis. Two cohorts were established: An ALS group consisting of 24 patients and a control group consisting of 38 healthy volunteers. Venous blood samples were collected for serum iron and ferritin analysis. The results indicated that the levels of serum iron were significantly decreased in patients with ALS (P<0.05), while there was no significant difference in serum ferritin between the ALS and control groups. However, the levels of serum ferritin were increased significantly in ALS patients with bulbar-onset (vs. limb-onset in females), dysphagia (vs. without dysphagia), longer disease duration (>12 months vs. ≤12 months in males) and lower ALS Functional Rating Scale-Revised score (<33 vs. ≥33; P<0.05). These results suggested that there was dysregulation of iron metabolism in Chinese Han patients with ALS and that serum ferritin may be a candidate biomarker of aggravation in these patients.

Iron regulatory protein (IRP)-iron responsive element (IRE) signaling pathway in human neurodegenerative diseases

The homeostasis of iron is vital to human health, and iron dyshomeostasis can lead to various disorders. Iron homeostasis is maintained by iron regulatory proteins (IRP1 and IRP2) and the iron-responsive element (IRE) signaling pathway. IRPs can bind to RNA stem-loops containing an IRE in the untranslated region (UTR) to manipulate translation of target mRNA. However, iron can bind to IRPs, leading to the dissociation of IRPs from the IRE and altered translation of target transcripts. Recently an IRE is found in the 5′-UTR of amyloid precursor protein (APP) and α-synuclein (α-Syn) transcripts. The levels of α-Syn, APP and amyloid β-peptide (Aβ) as well as protein aggregation can be down-regulated by IRPs but are up-regulated in the presence of iron accumulation. Therefore, inhibition of the IRE-modulated expression of APP and α-Syn or chelation of iron in patient’s brains has therapeutic significance to human neurodegenerative diseases. Currently, new pre-drug IRE inhibitors with therapeutic effects have been identified and are at different stages of clinical trials for human neurodegenerative diseases. Although some promising drug candidates of chemical IRE inhibitors and iron-chelating agents have been identified and are being validated in clinical trials for neurodegenerative diseases, future studies are expected to further establish the clinical efficacy and safety of IRE inhibitors and iron-chelating agents in patients with neurodegenerative diseases.

Elevated levels of ferritin in the cerebrospinal fluid of amyotrophic lateral sclerosis patients

OBJECTIVES

The aim of the study was to detect changes in the levels of ferritin heavy chain (FHC), ferritin light chain (FLC), and transferrin in the cerebrospinal fluid (CSF) and serum of amyotrophic lateral sclerosis (ALS) patients and to analyze the correlations between the levels of these proteins and various clinical parameters.

METHODS

Cerebrospinal fluid and serum samples were obtained from 54 ALS patients and 46 non-inflammatory neurological disease control (non-INDC) patients. CSF and serum FHC, FLC, and transferring levels were measured via the enzyme-linked immunosorbent method using a commercial ELISA kit, and the times from onset (durations), ALS functional rating scale-revised (ALSFRS-r) scores, and disease progression rates (DPRs) were analyzed by registered neurologists. Statistical analysis was performed via Prism software.

RESULTS

Compared with controls, ALS patients exhibited significantly increased FHC and FLC levels in CSF, which were positively correlated with DPR and negatively correlated with duration. Serum transferrin levels were significantly increased in ALS patients but were not correlated with disease progression. FHC and FLC in CSF rapidly increased as the disease worsened.

CONCLUSIONS

This study demonstrated that the clinical measurement of FHC and FLC in CSF may be beneficial for disease differentiation and evaluating progression in patients with ALS. Compared with levels in serum, the levels of FHC and FLC in CSF might be more reliable for diagnosing and assessing the progression of ALS.

Statins accelerate disease progression and shorten survival in SOD1(G93A) mice

INTRODUCTION

HMG-CoA reductase inhibitors (statins) and H63D HFE polymorphism may modify amyotrophic lateral sclerosis (ALS). We hypothesized that statins worsen phenotype in ALS mice, dependent on HFE genotype.

METHODS

Mice harboring SOD1(G93A) heterozygous for H67D Hfe (homologous to human H63D HFE) were administered simvastatin and/or coenzyme Q10, and were allowed to reach end stage. Disease progression was measured by grip strength. A separate group of animals was administered simvastatin and euthanized at the symptomatic 120-day time-point. Mitochondria from gastrocnemius muscle and lumbar spine were analyzed.

RESULTS

Simvastatin and H67D Hfe accelerated disease progression. Simvastatin decreased survival. Coenzyme Q10 did not rescue statin-induced effects. Statins did not alter mitochondrial protein levels.

CONCLUSIONS

Statins and Hfe genotype alter disease course in the ALS mouse model. Because the H63D HFE polymorphism is present in 30% of patients with ALS, studying disease progression in patients who receive statins, stratified for HFE genotype, may guide therapy. Muscle Nerve, 2016 Muscle Nerve 54: 284-291, 2016.

A Temporal Association between Accumulated Petrol (Gasoline) Lead Emissions and Motor Neuron Disease in Australia

Background: The age standardised death rate from motor neuron disease (MND) has increased from 1.29 to 2.74 per 100,000, an increase of 112.4% between 1959 and 2013. It is clear that genetics could not have played a causal role in the increased rate of MND deaths over such a short time span. We postulate that environmental factors are responsible for this rate increase. We focus on lead additives in Australian petrol as a possible contributing environmental factor. Methods: The associations between historical petrol lead emissions and MND death trends in Australia between 1962 and 2013 were examined using linear regressions. Results: Regression results indicate best fit correlations between a 20 year lag of petrol lead emissions and age-standardised female death rate (R² = 0.86, p = 4.88 × 10⁻²³), male age standardised death rate (R² = 0.86, p = 9.4 × 10⁻²³) and percent all cause death attributed to MND (R² = 0.98, p = 2.6 × 10⁻⁴⁴). Conclusion: Legacy petrol lead emissions are associated with increased MND death trends in Australia. Further examination of the 20 year lag between exposure to petrol lead and the onset of MND is warranted.

Low levels of aluminum can lead to behavioral and morphological changes associated with Alzheimer's disease and age-related neurodegeneration

Aluminum (Al) is a very common component of the earth's mineral composition. It is not essential element for life and is a constituent of rather inert minerals. Therefore, it has often been regarded as not presenting a significant health hazard. As a result, aluminum-containing agents been used in the preparation of many foodstuffs processing steps and also in elimination of particulate organic matter from water. More recently, the reduced pH of bodies of water resulting from acid rain has led to mobilization of aluminum-containing minerals into a more soluble form, and these have thus entered residential drinking water resources. By this means, the body burden of aluminum in humans has increased. Epidemiological and experimental findings indicate that aluminum is not as harmless as was previously thought, and that aluminum may contribute to the inception and advancement of Alzheimer's disease. Epidemiological data is reinforced by indications that aluminum exposure can result in excess inflammatory activity within the brain. Activation of the immune system not initiated by an infectious agent, typifies the aging brain and is even more augmented in several neurodegenerative diseases. The origin of most age-related neurological disorders is generally not known but as they are largely not of genetic derivation, their development is likely triggered by unknown environmental factors. There is a growing and consistent body of evidence that points to aluminum as being one such significant influence. Evidence is presented that reinforces the likelihood that aluminum is a factor speeding the rate of brain aging. Such acceleration would inevitably enlarge the incidence of age-related neurological diseases.

Quantitative susceptibility mapping of the motor cortex in amyotrophic lateral sclerosis and primary lateral sclerosis

OBJECTIVE

The diagnosis of amyotrophic lateral sclerosis (ALS) and primary lateral sclerosis (PLS) is often difficult because of a lack of disease biomarkers. The purpose of this study was to investigate quantitative susceptibility mapping (QSM) of the motor cortex as a potential quantitative biomarker for the diagnosis of ALS and PLS.

MATERIALS AND METHODS

From a retrospective database, QSM images of 16 patients with upper motor neuron disease (nine men [56%], seven women; mean age, 56.3 years; 12 with ALS, four with PLS) and 23 control patients (13 men [56%], 10 women; mean age, 56.6 years) were reviewed. Two neuroradiologists, blinded to diagnosis, qualitatively assessed QSM, T2- and T2*-weighted, and T2-weighted FLAIR images. Relative motor cortex susceptibility was calculated by subtraction of adjacent white matter and CSF signal intensity from mean motor cortex susceptibility on the axial image most representative of the right- or left-hand lobule, and ROC analysis was performed. The Fisher exact and Student t tests were used to evaluate for statistical differences between the groups.

RESULTS

Qualitatively, QSM had greater diagnostic accuracy than T2-weighted, T2*-weighted, or T2-weighted FLAIR imaging for the diagnosis of ALS and PLS. Quantitatively, relative motor cortex susceptibility was found to be significantly greater in patients with motor neuron disease than in control patients (46.0 and 35.0 ppb; p < 0.001). ROC analysis showed an AUC of 0.88 (p < 0.0001) and an optimal cutoff value of 40.5 ppb for differentiating control patients from patients with ALS or PLS (sensitivity, 87.5%; specificity, 87.0%).

CONCLUSION

QSM is a sensitive and specific quantitative biomarker of iron deposition in the motor cortex in ALS and PLS.

Biological follow-up in amyotrophic lateral sclerosis: decrease in creatinine levels and increase in ferritin levels predict poor prognosis

BACKGROUND AND PURPOSE

Amyotrophic lateral sclerosis (ALS) is a fatal disorder of the motor neuron system, with a median survival of 2 to 4 years and a wide variety of prognosis. Thus, there is a critical need for diagnosis and prognosis biomarkers to improve the care of patients in routine practice. In this study, we aimed to determine prognostic value of routine biochemical markers in sporadic ALS (SALS).

METHODS

We retrospectively collected clinical and biological data obtained during the systematic routine monitoring of 216 sporadic ALS patients. The main outcomes were disease duration and annual decline of Revised ALS Functional Rating Scale (ALSFRS-R). Changes to these biological variables over time were assessed, in link with disease progression.

RESULTS

We found that concentrations of creatinine (P=0.0166) and ferritin (P=0.0306) changed significantly during the progression of ALS. A reduction of creatinine levels and an increase of ferritin levels were associated with disease progression. Multivariate analysis showed that early variation of ferritin was an independent predictive factor of patient survival (P=0.0048).

CONCLUSION

Changes to ferritin and creatinine levels with time are associated with ALS progression. This is the first study describing the changes to these biological variables during ALS progression.

Serum ferritin is elevated in amyotrophic lateral sclerosis patients

Our objective was to measure serum ferritin levels, which reflect iron metabolism, in ALS patients versus healthy and disease controls, and determine whether serum ferritin levels correlate with survival. We retrospectively analyzed data from 138 ALS patients, 152 healthy controls, and 82 disease controls. Gender, age, site of onset, and dates of symptom onset and death were recorded. Survival was defined as the time from symptom onset to death. Serum ferritin levels were measured using immunoassay. ANOVA and Pearson's correlation were used to compare ferritin levels between groups and test the association between ferritin levels and age and survival. Ferritin levels were categorized into high and low groups, and Kaplan-Meier analysis performed. Results showed that gender proportions differed between ALS patients versus healthy and disease controls, and gender affected serum ferritin levels. Ferritin comparisons were stratified for gender. In both males and females, ferritin levels were higher in ALS patients versus healthy and disease controls. However, ferritin levels were unrelated to survival in either gender, by tests of association or survival analysis. In conclusion, ALS patients have altered iron metabolism that is not simply due to the presence of neurological disease. Serum ferritin levels alone are not sufficient to predict survival.

Serum ferritin is an important inflammatory disease marker, as it is mainly a leakage product from damaged cells

"Serum ferritin" presents a paradox, as the iron storage protein ferritin is not synthesised in serum yet is to be found there. Serum ferritin is also a well known inflammatory marker, but it is unclear whether serum ferritin reflects or causes inflammation, or whether it is involved in an inflammatory cycle. We argue here that serum ferritin arises from damaged cells, and is thus a marker of cellular damage. The protein in serum ferritin is considered benign, but it has lost (i.e. dumped) most of its normal complement of iron which when unliganded is highly toxic. The facts that serum ferritin levels can correlate with both disease and with body iron stores are thus expected on simple chemical kinetic grounds. Serum ferritin levels also correlate with other phenotypic readouts such as erythrocyte morphology. Overall, this systems approach serves to explain a number of apparent paradoxes of serum ferritin, including (i) why it correlates with biomarkers of cell damage, (ii) why it correlates with biomarkers of hydroxyl radical formation (and oxidative stress) and (iii) therefore why it correlates with the presence and/or severity of numerous diseases. This leads to suggestions for how one might exploit the corollaries of the recognition that serum ferritin levels mainly represent a consequence of cell stress and damage.

H63D HFE genotype accelerates disease progression in animal models of amyotrophic lateral sclerosis

H63D HFE is associated with iron dyshomeostasis and oxidative stress; each of which plays an important role in amyotrophic lateral sclerosis (ALS) pathogenesis. To examine the role of H63D HFE in ALS, we generated a double transgenic mouse line (SOD1/H67D) carrying the H67D HFE (homologue of human H63D) and SOD1(G93A) mutations. We found double transgenic mice have shorter survival and accelerated disease progression. We examined parameters in the lumbar spinal cord of double transgenic mice at 90days (presymptomatic), 110days (symptomatic) and end-stage. Transferrin receptor and L-ferritin expression, both indicators of iron status, were altered in double transgenic and SOD1 mice starting at 90days, indicating loss of iron homeostasis in these mice. However, double transgenic mice had higher L-ferritin expression than SOD1 mice. Double transgenic mice exhibited increased Iba-1 immunoreactivity and caspase-3 levels, indicating increased microglial activation which would be consistent with the higher L-ferritin levels. Although both SOD1 and double transgenic mice had increased GFAP expression, the magnitude of the increase was higher in double transgenic mice at 110days, suggesting increased gliosis in these mice. Increased hemeoxygenase-1 and decreased nuclear factor E2-related factor 2 levels in double transgenic mice strongly suggest the accelerated disease process could be associated with increased oxidative stress. There was no evidence of TAR-DNA-binding protein 43 mislocalization to the cytoplasm in double transgenic mice; however, there was evidence suggesting neurofilament disruption, which has been reported in ALS. Our findings indicate H63D HFE modifies ALS pathophysiology via pathways involving oxidative stress, gliosis and disruption of cellular functions.

The potential for transition metal-mediated neurodegeneration in amyotrophic lateral sclerosis

Modulations of the potentially toxic transition metals iron (Fe) and copper (Cu) are implicated in the neurodegenerative process in a variety of human disease states including amyotrophic lateral sclerosis (ALS). However, the precise role played by these metals is still very much unclear, despite considerable clinical and experimental data suggestive of a role for these elements in the neurodegenerative process. The discovery of mutations in the antioxidant enzyme Cu/Zn superoxide dismutase 1 (SOD-1) in ALS patients established the first known cause of ALS. Recent data suggest that various mutations in SOD-1 affect metal-binding of Cu and Zn, in turn promoting toxic protein aggregation. Copper homeostasis is also disturbed in ALS, and may be relevant to ALS pathogenesis. Another set of interesting observations in ALS patients involves the key nutrient Fe. In ALS patients, Fe loading can be inferred by studies showing increased expression of serum ferritin, an Fe-storage protein, with high serum ferritin levels correlating to poor prognosis. Magnetic resonance imaging of ALS patients shows a characteristic T₂ shortening that is attributed to the presence of Fe in the motor cortex. In mutant SOD-1 mouse models, increased Fe is also detected in the spinal cord and treatment with Fe-chelating drugs lowers spinal cord Fe, preserves motor neurons, and extends lifespan. Inflammation may play a key causative role in Fe accumulation, but this is not yet conclusive. Excess transition metals may enhance induction of endoplasmic reticulum (ER) stress, a system that is already under strain in ALS. Taken together, the evidence suggests a role for transition metals in ALS progression and the potential use of metal-chelating drugs as a component of future ALS therapy.

Iron metabolism disturbance in a French cohort of ALS patients

OBJECTIVE

The aim of this study was to assess iron status in a cohort of amyotrophic lateral sclerosis (ALS) patients compared to controls in order to evaluate these parameters as a risk factor or a modifying factor of ALS.

METHODS

We collected serum iron, ferritin, transferrin, total iron-binding capacity, and transferrin saturation coefficient (TSC) from 104 ALS patients at the time of diagnosis and from 145 controls. We reported phenotypic characteristics and evolution parameters such as ALSFRS-R and forced vital capacity at diagnosis and after one year of follow-up. In a first step we compared iron status between ALS patients and controls, and then we evaluated the relation between iron status and disease evolution of ALS patients using univariate and multivariate analysis.

RESULTS

We observed increased concentrations of serum iron (P = 0.002) and ferritin (P < 0.0001) and increased TSC (P = 0.017) in ALS patients. We also showed an association between markers of iron status and high body weight loss in ALS patients. The multivariate analysis of survival highlighted a significant relation between ferritin level and disease duration (P = 0.038).

CONCLUSION

This is the first study showing a higher concentration of serum iron in ALS patients, strengthening the involvement of a deregulation of iron metabolism in ALS.

Alzheimer's disease therapeutics targeted to the control of amyloid precursor protein translation: maintenance of brain iron homeostasis

The neurotoxicity of amyloid beta (Aβ), a major cleavage product of the amyloid precursor protein (APP), is enhanced by iron, as found in the amyloid plaques of Alzheimer's disease (AD) patients. By contrast, the long-known neuroprotective activity of APP is evident after α-secretase cleavage of the precursor to release sAPPα, and depends on the iron export actions of APP itself. The latter underlie its neurotrophic and protective effects in facilitating the homeostatic actions of ferroportin mediated-iron export. Thus APP-dependent iron export may alleviate oxidative stress by minimizing labile iron thus protecting neurons from iron overload during stroke and hemorrhage. Consistent with this, altered phosphorylation of iron-regulatory protein-1 (IRP1) and its signaling processes play a critical role in modulating APP translation via the 5' untranslated region (5'UTR) of its transcript. The APP 5'UTR region encodes a functional iron-responsive element (IRE) RNA stem loop that represents a potential target for modulating APP production. Targeted regulation of APP gene expression via the modulation of 5'UTR sequence function represents a novel approach for the potential treatment of AD since altering APP translation can be used to improve both the protective brain iron balance and provide anti-amyloid efficacy. Approved drugs including paroxetine and desferrioxamine and several novel compounds have been identified that suppress abnormal metal-promoted Aβ accumulation with a subset of these acting via APP 5'UTR-dependent mechanisms to modulate APP translation and cleavage to generate the non-toxic sAPPα.

Proteome analysis of body fluids for amyotrophic lateral sclerosis biomarker discovery

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder of motor neurons leading to death of the patients, mostly within 2-5 years after disease onset. The pathomechanism of motor neuron degeneration is only partially understood and therapeutic strategies based on mechanistic insights are largely ineffective. The discovery of reliable biomarkers of disease diagnosis and progression is the sine qua non of both the revelation of insights into the ALS pathomechanism and the assessment of treatment efficacies. Proteomic approaches are an important pillar in ALS biomarker discovery. Cerebrospinal fluid is the most promising body fluid for differential proteome analyses, followed by blood (serum, plasma), and even urine and saliva. The present study provides an overview about reported peptide/protein biomarker candidates that showed significantly altered levels in certain body fluids of ALS patients. These findings have to be discussed according to proposed pathomechanisms to identify modifiers of disease progression and to pave the way for the development of potential therapeutic strategies. Furthermore, limitations and advantages of proteomic approaches for ALS biomarker discovery in different body fluids and reliable validation of biomarker candidates have been addressed.

Characterization of biometal profiles in neurological disorders

This review summarizes the findings on dysregulation of metal ions in neurological diseases and tries to develop and predict specific biometal profiles.

Prolonged exposure to low levels of aluminum leads to changes associated with brain aging and neurodegeneration

Aluminum is one of the most common metal elements in the earth's crust. It is not an essential element for life and has commonly been thought of as a rather inert and insoluble mineral. Therefore, it has often been regarded as not posing a significant health hazard. In consequence, aluminum-containing agents been used in many food processing steps and also in removal by flocculation of particulate organic matter from water. In recent years, acid rain has tended to mobilize aluminum-containing minerals into a more soluble form, ionic Al(3+), which has found their way into many reservoirs that constitute residential drinking water resources. As a result, the human body burden of aluminum has increased. Epidemiological studies suggest that aluminum may not be as innocuous as was previously thought and that aluminum may actively promote the onset and progression of Alzheimer's disease. Epidemiological data is strengthened by experimental evidence of aluminum exposure leading to excess inflammatory activity within the brain. Such apparently irrelevant immune activity unprovoked by an exogenous infectious agent characterizes the aging brain and is even more pronounced in several neurodegenerative diseases. The causation of most of these age-related neurological disorders is not understood but since they are generally not genetic, one must assume that their development is underlain by unknown environmental factors. There is an increasing and coherent body of evidence that implicates aluminum as being one such significant factor. Evidence is outlined supporting the concept of aluminum's involvement in hastening brain aging. This acceleration would then inevitably lead to increased incidence of specific age-related neurological diseases.

Amyotrophic lateral sclerosis: new insights into underlying molecular mechanisms and opportunities for therapeutic intervention

Recent years have witnessed a renewed interest in the pathogenic mechanisms of amyotrophic lateral sclerosis (ALS), a late-onset progressive degeneration of motor neurons. The discovery of new genes associated with the familial form of the disease, along with a deeper insight into pathways already described for this disease, has led scientists to reconsider previous postulates. While protein misfolding, mitochondrial dysfunction, oxidative damage, defective axonal transport, and excitotoxicity have not been dismissed, they need to be re-examined as contributors to the onset or progression of ALS in the light of the current knowledge that the mutations of proteins involved in RNA processing, apparently unrelated to the previous "old partners," are causative of the same phenotype. Thus, newly envisaged models and tools may offer unforeseen clues on the etiology of this disease and hopefully provide the key to treatment.

Elevated serum ferritin is associated with reduced survival in amyotrophic lateral sclerosis

Background

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder caused by the loss of motor neurons. Its etiology remains unknown, but several hypothesis have been raised to explain motor neuron death, including oxidative stress. Dysregulation of cellular iron metabolism can lead to increased oxidative stress, and existing data argue for a role of iron metabolism in ALS pathophysiology.

Methods

We performed a retrospective analysis of iron metabolism (IM) variables (serum levels of iron, transferrin, ferritin, and TSC for Transferrin Saturation Coefficient) in a cohort of 694 ALS patients and 297 healthy controls.

Results

Serum ferritin levels and TSC were higher, whereas serum transferrin levels were lower in ALS patients than controls. In addition, patients with a high level serum ferritin had a shorter survival time compared to those with low level serum ferritin (618 days versus 921 days for men subgroup; p = .007). Site of onset and ALS-FRS score were not associated with IM variables.

Conclusion

This study suggests that ALS patients may have increased iron storage, as measured by increased serum ferritin and TSC. Elevated serum ferritin may also have a deleterious impact on survival in ALS.

Relationships between disease progression and serum levels of lipid, urate, creatinine and ferritin in Japanese patients with amyotrophic lateral sclerosis: a cross-sectional study

OBJECTIVE

Previous studies have reported distinct serological profiles of lipid, urate and ferritin in Western patients with amyotrophic lateral sclerosis (ALS). We aimed to examine the levels of these serological factors and their relationship to disease progression in Japanese ALS patients.

METHODS

Ninety-two patients with definite or probable ALS who fulfilled the revised El Escorial criteria were analyzed for clinical and serological variables. Serological data at the time diagnosed with ALS were compared to those of 92 age/sex/body mass index-matched healthy controls.

RESULTS

Compared to controls, urate and creatinine (Cr) levels were decreased and ferritin levels were increased significantly in sera of male and female patients with ALS. Significant increases of serum total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and triglyceride levels were found in female ALS patients. The annual decline of ALS Functional Rating Scale-Revised (ALS-FRS) and forced vital capacity (FVC) were inversely correlated with serum TC, LDL-C, Cr and urate levels, and were positively correlated with serum ferritin levels. Multivariate analysis showed that the rapid worsening of annual ALS-FRS and FVC was associated with serum levels of TC, LDL-C, Cr, urate and ferritin.

CONCLUSION

The present study indicated that serum levels of TC, LDL-C, Cr, urate and ferritin were correlated with clinical deterioration in ALS patients. These results are similar to those in Western patients. Metabolic and nutritional conditions of lipid, urate and iron could contribute to disease progression in ALS patients. Further studies investigating high nutrition diets and iron chelation for the treatment of ALS are warranted.

Association between divalent metal transport 1 encoding gene (SLC11A2) and disease duration in amyotrophic lateral sclerosis

BACKGROUND

Dysregulation of iron homeostasis is one possible pathophysiological mechanism involved in motor neuron degeneration in amyotrophic lateral sclerosis (ALS). SLC11A2 gene encodes the divalent metal transport 1 (DMT1) mediating iron transport in cerebral endosomal compartments. The objective of the study was to analyze DMT1 as a possible risk or modulating factor in sporadic ALS (SALS).

METHODS

We performed a case-control association study on an intronic polymorphism (rs407135) previously analyzed in another neurodegenerative disease, Alzheimer's disease. This polymorphism was studied by DNA sequencing in 579 French patients with SALS and 517 healthy matched individuals. The clinical characteristics of patients were analyzed in relation to their genotypes.

RESULTS

We observed that the C allele of rs407135 in SLC11A2 was associated with a shorter disease duration in SALS patients with onset in the legs [Hazard ratio: 1.5 [1.1-2.1] (p=0.02)]. These results are in line with previous observations suggesting that bulbar and spinal motor neurons have different metabolic regulation and gene expression profiles.

CONCLUSIONS

Our findings support an implication for iron metabolism in ALS and suggest that the genotype of the SLC11A2 gene could modulate the duration of the disease in French SALS patients.

Copper and zinc metallation status of copper-zinc superoxide dismutase from amyotrophic lateral sclerosis transgenic mice

Mutations in the metalloenzyme copper-zinc superoxide dismutase (SOD1) cause one form of familial amyotrophic lateral sclerosis (ALS), and metals are suspected to play a pivotal role in ALS pathology. To learn more about metals in ALS, we determined the metallation states of human wild-type or mutant (G37R, G93A, and H46R/H48Q) SOD1 proteins from SOD1-ALS transgenic mice spinal cords. SOD1 was gently extracted from spinal cord and separated into insoluble (aggregated) and soluble (supernatant) fractions, and then metallation states were determined by HPLC inductively coupled plasma MS. Insoluble SOD1-rich fractions were not enriched in copper and zinc. However, the soluble mutant and WT SOD1s were highly metallated except for the metal-binding-region mutant H46R/H48Q, which did not bind any copper. Due to the stability conferred by high metallation of G37R and G93A, it is unlikely that these soluble SOD1s are prone to aggregation in vivo, supporting the hypothesis that immature nascent SOD1 is the substrate for aggregation. We also investigated the effect of SOD1 overexpression and disease on metal homeostasis in spinal cord cross-sections of SOD1-ALS mice using synchrotron-based x-ray fluorescence microscopy. In each mouse genotype, except for the H46R/H48Q mouse, we found a redistribution of copper between gray and white matters correlated to areas of high SOD1. Interestingly, a disease-specific increase of zinc was observed in the white matter for all mutant SOD1 mice. Together these data provide a picture of copper and zinc in the cell as well as highlight the importance of these metals in understanding SOD1-ALS pathology.

Towards a unifying, systems biology understanding of large-scale cellular death and destruction caused by poorly liganded iron: Parkinson's, Huntington's, Alzheimer's, prions, bactericides, chemical toxicology and others as examples

Exposure to a variety of toxins and/or infectious agents leads to disease, degeneration and death, often characterised by circumstances in which cells or tissues do not merely die and cease to function but may be more or less entirely obliterated. It is then legitimate to ask the question as to whether, despite the many kinds of agent involved, there may be at least some unifying mechanisms of such cell death and destruction. I summarise the evidence that in a great many cases, one underlying mechanism, providing major stresses of this type, entails continuing and autocatalytic production (based on positive feedback mechanisms) of hydroxyl radicals via Fenton chemistry involving poorly liganded iron, leading to cell death via apoptosis (probably including via pathways induced by changes in the NF-κB system). While every pathway is in some sense connected to every other one, I highlight the literature evidence suggesting that the degenerative effects of many diseases and toxicological insults converge on iron dysregulation. This highlights specifically the role of iron metabolism, and the detailed speciation of iron, in chemical and other toxicology, and has significant implications for the use of iron chelating substances (probably in partnership with appropriate anti-oxidants) as nutritional or therapeutic agents in inhibiting both the progression of these mainly degenerative diseases and the sequelae of both chronic and acute toxin exposure. The complexity of biochemical networks, especially those involving autocatalytic behaviour and positive feedbacks, means that multiple interventions (e.g. of iron chelators plus antioxidants) are likely to prove most effective. A variety of systems biology approaches, that I summarise, can predict both the mechanisms involved in these cell death pathways and the optimal sites of action for nutritional or pharmacological interventions.