Biomarkers in amyotrophic lateral sclerosis

On the development of markers for pathological TDP-43 in amyotrophic lateral sclerosis with and without dementia

Pathological 43-kDa transactive response sequence DNA-binding protein (TDP-43) has been recognized as the major disease protein in amyotrophic lateral sclerosis (ALS), frontotemporal lobar degeneration with ubiquitin positive, tau and α-synuclein negative inclusions (FTLD-U) and the transitional forms between these multisystem conditions. In order to develop TDP-43 into a successful ALS biomarker, the natural history of TDP-43 pathology needs to be characterized and the underlying pathophysiology established. Here we propose a spatial and temporal "two-axes" model of central nervous system vulnerability for TDP-43 linked degeneration and review recent studies on potential biomarkers related to pathological TDP-43 in the cerebrospinal fluid (CSF), blood, and skeletal muscle. The model includes the following two arms: Firstly, a "motor neuron disease" or "spinal cord/brainstem to motor cortex" axis (with degeneration possibly ascending from the lower motor neurons to the upper motor neurons); and secondly, a "dementia" or "corticoid/allocortex to neocortex" axis (with a probable spread of TDP-43 linked degeneration from the mediotemporal lobe to wider mesocortical and neocortical brain areas). At the cellular level, there is a gradual disappearance of normal TDP-43 in the nucleus in combination with the formation of pathological aggregates in the cell body and cellular processes, which can also be used to identify the stage of the disease process. Moreover, TDP-43 lesions in subpial/subependymal or perivascular localizations have been noted, and this might account for increased CSF and blood TDP-43 levels through mechanisms that remain to be elucidated.

Preoperative assessment and preparation of patients with neurologic disorders

Ageing of populataion world wide has significant contribution as one of the major risk factor for neurodegenerative disorders. The patients with neurodegenerative as well as other neuological diseases presented the population with possible great need either of small or big surgical intervention. There are several important issues in patients with neurological diseases: the nature, disease duration, therapy, the patient's ability to live without assistance. Neurological disease may become worst by general and regional anesthesia. Stopping therapy may lead to worsening of neurological diseases. One of the main common threat is the risk of significant cardiorespiratory complications, which is important in assessing operational risk, in preoperative preparation and in terms of postoperative recovery and outcomes of surgical treatment. This has resulted in greater preoperative care by detailed patient history evaluation and examination, patient information and informed consent. Besides the effect of the anaesthetic technique upon the course of the disease, there is also the interaction of drugs administered during anaesthesia and patient medication. Several undiagnosed diseases may be disclosed following a surgical/anaesthetic intervention.

Impaired structural motor connectome in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a severe neurodegenerative disease selectively affecting upper and lower motor neurons. Patients with ALS suffer from progressive paralysis and eventually die on average after three years. The underlying neurobiology of upper motor neuron degeneration and its effects on the complex network of the brain are, however, largely unknown. Here, we examined the effects of ALS on the structural brain network topology in 35 patients with ALS and 19 healthy controls. Using diffusion tensor imaging (DTI), the brain network was reconstructed for each individual participant. The connectivity of this reconstructed brain network was compared between patients and controls using complexity theory without - a priori selected - regions of interest. Patients with ALS showed an impaired sub-network of regions with reduced white matter connectivity (p = 0.0108, permutation testing). This impaired sub-network was strongly centered around primary motor regions (bilateral precentral gyrus and right paracentral lobule), including secondary motor regions (bilateral caudal middle frontal gyrus and pallidum) as well as high-order hub regions (right posterior cingulate and precuneus). In addition, we found a significant reduction in overall efficiency (p = 0.0095) and clustering (p = 0.0415). From our findings, we conclude that upper motor neuron degeneration in ALS affects both primary motor connections as well as secondary motor connections, together composing an impaired sub-network. The degenerative process in ALS was found to be widespread, but interlinked and targeted to the motor connectome.

Soluble beta-amyloid precursor protein is related to disease progression in amyotrophic lateral sclerosis

Background

Biomarkers of disease progression in amyotrophic lateral sclerosis (ALS) could support the identification of beneficial drugs in clinical trials. We aimed to test whether soluble fragments of beta-amyloid precursor protein (sAPPα and sAPPß) correlated with clinical subtypes of ALS and were of prognostic value.

Methodology/Principal Findings

In a cross-sectional study including patients with ALS (N = 68) with clinical follow-up data over 6 months, Parkinson's disease (PD, N = 20), and age-matched controls (N = 40), cerebrospinal fluid (CSF) levels of sAPPα a, sAPPß and neurofilaments (NfH^SMI35) were measured by multiplex assay, Progranulin by ELISA. CSF sAPPα and sAPPß levels were lower in ALS with a rapidly-progressive disease course (p = 0.03, and p = 0.02) and with longer disease duration (p = 0.01 and p = 0.01, respectively). CSF NfH^SMI35 was elevated in ALS compared to PD and controls, with highest concentrations found in patients with rapid disease progression (p<0.01). High CSF NfH^SMI3 was linked to low CSF sAPPα and sAPPß (p = 0.001, and p = 0.007, respectively). The ratios CSF NfH^SMI35/CSF sAPPα,-ß were elevated in patients with fast progression of disease (p = 0.002 each). CSF Progranulin decreased with ongoing disease (p = 0.04).

Conclusions

This study provides new CSF candidate markers associated with progression of disease in ALS. The data suggest that a deficiency of cellular neuroprotective mechanisms (decrease of sAPP) is linked to progressive neuro-axonal damage (increase of NfH^SMI35) and to progression of disease.

Mesenchymal stromal cells prolong the lifespan in a rat model of amyotrophic lateral sclerosis

BACKGROUND AIMS

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder characterized by the loss of brain and spinal cord motor neurons (MN). The intraspinal and systemic grafting of mesenchymal stromal cells (MSC) was used to treat symptomatic transgenic rats overexpressing human superoxide dismutase 1 (SOD1) in order to alleviate the disease course and prolong the animals' lifespan.

METHODS

At the age of 16 weeks (disease onset) the rats received two grafts of MSC expressing green fluorescent protein (GFP(+) MSC) on the same day, intraspinally (10(5) cells) and intravenously (2 × 10(6) cells). Sham-treated animals were injected with phosphate-buffered saline (PBS). Motor activity, grip strength and body weight were tested, followed by immunohistochemical analysis.

RESULTS

The combined grafting of MSC into symptomatic rats had a significant effect on motor activity and grip strength starting 4 weeks after transplantation. The lifespan of animals in the treated group was 190 ± 3.33 days compared with 179 ± 3.6 days in the control group of animals. Treated rats had a larger number of MN at the thoracic and lumbar levels; these MN were of larger size, and the intensity of terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick-end labeling (TUNEL) staining in the somas of apoptotic MN at the thoracic level was much lower than in sham-treated animals. Transplanted GFP(+) MSC survived in the spinal cord until the end stage of the disease and migrated both rostrally and caudally from the injection site.

CONCLUSIONS

Intraspinal and intravenous transplantation of MSC has a beneficial and possibly synergistic effect on the lifespan of ALS animals.

The topography of brain microstructural damage in amyotrophic lateral sclerosis assessed using diffusion tensor MR imaging

BACKGROUND AND PURPOSE

ALS leads to macrostructural (ie, cortical atrophy and hyperintensities along the corticospinal tract) and microstructural (ie, gray matter intrinsic damage) central nervous system abnormalities. We used a multimodal voxelwise imaging approach to assess microstructural changes independent of macrostructural volume loss in patients with ALS compared with HCs.

MATERIALS AND METHODS

Twenty-three patients with ALS and 14 HCs were studied. Conventional imaging and DTI were performed. Images were processed by using SPM5 to assess measures of gray and white matter atrophy as well as microstructural damage (ie, MD and FA). DTI alterations independent of volume loss were investigated.

RESULTS

When we accounted for both gray and white matter atrophy, patients with ALS showed increased MD values in several gray and white matter areas mainly located in the orbitofrontal and frontotemporal regions bilaterally, in the right genu of the corpus callosum, and in the right posterior limb of the internal capsule. When we accounted for white matter volume loss, patients with ALS showed decreased FA along the corticospinal tract bilaterally and in the left inferior frontal lobe relative to HCs. The MD of the orbitofrontal regions bilaterally was associated significantly with disease duration.

CONCLUSIONS

In patients with ALS, DTI detects microstructural changes independent of brain tissue loss. The affected regions included both motor and extramotor areas. The extent of ALS-related DTI abnormalities was greater than that disclosed by the volumetric analysis.

Electrical impedance myography for monitoring motor neuron loss in the SOD1 G93A amyotrophic lateral sclerosis rat

OBJECTIVE

Human studies have shown that electrical impedance myography (EIM), a technique based on the surface application of high-frequency, low-intensity electrical current to localized areas of muscle, is sensitive to muscle denervation. In this study, we examined the role of EIM as a potential biomarker for assessing ALS disease progression in the SOD1 transgenic rat by comparing it to motor unit number estimation (MUNE).

METHODS

Multi-frequency EIM and MUNE were performed twice weekly in 16 rats from approximately 10 weeks of age onward. Four different EIM measures were evaluated, including the previously studied 50 kHz phase and three condensed multi-frequency parameters.

RESULTS

The rate of deterioration in the multi-frequency phase data from 100-500 kHz had the strongest correlation to survival (ρ=0.79, p<0.001), surpassing that of MUNE (ρ=0.57, p=0.020). These two measures were also strongly correlated (ρ=-0.94, p<0.001) to one another.

CONCLUSIONS

These findings support that EIM is an effective tool for assessing disease progression in the ALS rat.

SIGNIFICANCE

Given its ease of application and ability to assess virtually any superficial muscle, EIM deserves further study as a biomarker in human ALS clinical therapeutic trials.

Effects of gender in amyotrophic lateral sclerosis

BACKGROUND

There is evidence that amyotrophic lateral sclerosis (ALS), also known as motor neuron disease (MND), is more common in men than in women and that gender influences the clinical features of the disease. The causes of this are unknown.

OBJECTIVE

This review examines the gender differences that are found in ALS and postulates reasons for these differences.

METHODS

A literature review of PubMed (with no date limits) was performed to find information about gender differences in the incidence, prevalence, and clinical features of ALS, using the search terms ALS or MND and gender or sex, ALS prevalence, and SOD1 mice and gender. Articles were reviewed for information about gender differences, together with other articles that were already known to the authors.

RESULTS

The incidence and prevalence of ALS are greater in men than in women. This gender difference is seen in large studies that included all ALS patients (sporadic and familial), but is not seen when familial ALS is studied independently. Men predominate in the younger age groups of patients with ALS. Sporadic ALS has different clinical features in men and women, with men having a greater likelihood of onset in the spinal regions, and women tending to have onset in the bulbar region. Gender appears to have no clear effect on survival. In animals with superoxide dismutase 1 (sod1) mutations, sex does affect the clinical course of disease, with earlier onset in males. Possible reasons for the differences in ALS between men and women include different exposures to environmental toxins, different biological responses to exogenous toxins, and possibly underlying differences between the male and female nervous systems and different abilities to repair damage.

CONCLUSIONS

There is a complex interaction between gender and clinical phenotypes in ALS. Understanding the causes of the gender differences could give clues to processes that modify the disease.

Respiratory motoneurons and pathological conditions: lessons from hypoglossal motoneurons challenged by excitotoxic or oxidative stress

Hypoglossal motoneurons (HMs) are respiration-related brainstem neurons that command rhythmic contraction of the tongue muscles in concert with the respiratory drive. In experimental conditions, HMs can exhibit a range of rhythmic patterns that may subserve different motor outputs and functions. Neurodegenerative diseases like amyotrophic lateral sclerosis (ALS; Lou-Gehrig disease) often damage HMs with distressing symptoms like dysarthria, dysphagia and breathing difficulty related to degeneration of respiratory motoneurons. While the cause of ALS remains unclear, early diagnosis remains an important goal for potential treatment because fully blown clinical symptoms appear with degeneration of about 30% motoneurons. Using a simple in vitro model of the rat brainstem to study the consequences of excitotoxicity or oxidative stress (believed to occur during the onset of ALS) on HMs, it is possible to observe distinct electrophysiological effects associated with HM experimental pathology. In fact, excitotoxicity caused by glutamate uptake block triggers sustained bursting and enhanced synaptic transmission, whereas oxidative stress generates slow depolarization, augmented repeated firing, and decreased synaptic transmission. In either case, only a subpopulation of HMs shows abnormal functional changes. Although these two insults induce separate functional signatures, the consequences on HMs after a few hours are similar and are preceded by activation of the stress transcription factor ATF-3. The deleterious action of excitotoxicity is inhibited by early administration of riluzole, a drug currently employed for the symptomatic treatment of ALS, demonstrating that this in vitro model can be useful for testing potential neuroprotective agents.

Progesterone and cortisol levels in sporadic amyotrophic lateral sclerosis (sALS): correlation with prognostic factors

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder. Worse prognostic factors in ALS are: (a) advanced age, (b) bulbar onset, and (c) short time between onset and diagnosis. Progesterone (PROG) has been associated with neuroprotective and promyelinating activities in injury, ischemia and degeneration of the central and peripheral nervous system. Cortisol is connected to the response to stress situations and could contribute to neuronal damage. The goals of this study were: (i) to investigate whether PROG levels are modified by ALS prognostic factors and (ii) to determine whether cortisol follows the same pattern. We determined serum steroid levels in 27 patients with sporadic ALS (sALS) and 21 controls. Both steroid hormones showed significantly increased levels in ALS patients versus controls (mean±SEM: PROG ALS vs.

CONTROL

0.54±0.05 vs. 0.39±0.04 ng/mL, p<0.05; cortisol ALS vs.

CONTROL

17.02±1.60 vs. 11.83±1.38 μg/dL, p<0.05).1 A trend towards higher levels of PROG were demonstrated in spinal onset patients compared with bulbar onset (p=0.07), positive correlation with survival time (RRho=0.43, p=0.04) and a trend towards significance with time to diagnosis (RRho=0.36, p=0.06). These correlations have not been demonstrated for cortisol. Elevated serum steroid levels in sALS were probably due to hyperfunction of the hypothalamic-pituitary-adrenal axis. However, only PROG correlated with better prognostic factors. Future studies will determine if the different behavior of PROG and cortisol relate to any particular role they might play during the course of this motor neuron degenerative disease.

Use of peripheral blood transcriptome biomarkers for epilepsy prediction

There are currently no predictive methods to identify patients who suffered an initial brain injury and are at high risk of developing chronic epilepsy. Consequently, treatments aimed at epilepsy prevention that would target the underlying epileptogenic process are neither available nor being developed. After a brain injury or any other initial precipitating event (IPE) to the development of epilepsy, pathological changes may occur in forms of inflammation, damage in the blood brain barrier, neuron loss, gliosis, axon sprouting, etc., in multiple brain areas. Recent studies provide connections between various kinds of brain pathology and alterations in the peripheral blood transcriptome. In this review we discuss the possibility of using peripheral blood transcriptome biomarkers for the detection of epileptogenesis and consequently, subjects at high risk of developing epilepsy.

G-CSF prevents the progression of structural disintegration of white matter tracts in amyotrophic lateral sclerosis: a pilot trial

Background

The hematopoietic protein Granulocyte-colony stimulating factor (G-CSF) has neuroprotective and -regenerative properties. The G-CSF receptor is expressed by motoneurons, and G-CSF protects cultured motoneuronal cells from apoptosis. It therefore appears as an attractive and feasible drug candidate for the treatment of amyotrophic lateral sclerosis (ALS). The current pilot study was performed to determine whether treatment with G-CSF in ALS patients is feasible.

Methods

Ten patients with definite ALS were entered into a double-blind, placebo-controlled, randomized trial. Patients received either 10 µg/kg BW G-CSF or placebo subcutaneously for the first 10 days and from day 20 to 25 of the study. Clinical outcome was assessed by changes in the ALS functional rating scale (ALSFRS), a comprehensive neuropsychological test battery, and by examining hand activities of daily living over the course of the study (100 days). The total number of adverse events (AE) and treatment-related AEs, discontinuation due to treatment-related AEs, laboratory parameters including leukocyte, erythrocyte, and platelet count, as well as vital signs were examined as safety endpoints.

Furthermore, we explored potential effects of G-CSF on structural cerebral abnormalities on the basis of voxel-wise statistics of Diffusion Tensor Imaging (DTI), brain volumetry, and voxel-based morphometry.

Results

Treatment was well-tolerated. No significant differences were found between groups in clinical tests and brain volumetry from baseline to day 100. However, DTI analysis revealed significant reductions of fractional anisotropy (FA) encompassing diffuse areas of the brain when patients were compared to controls. On longitudinal analysis, the placebo group showed significant greater and more widespread decline in FA than the ALS patients treated with G-CSF.

Conclusions

Subcutaneous G-CSF treatment in ALS patients appears as feasible approach. Although exploratory analysis of clinical data showed no significant effect, DTI measurements suggest that the widespread and progressive microstructural neural damage in ALS can be modulated by G-CSF treatment. These findings may carry significant implications for further clinical trials on ALS using growth factors.

Trial Registration

ClinicalTrials.gov NCT00298597

Amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is an idiopathic, fatal neurodegenerative disease of the human motor system. In this Seminar, we summarise current concepts about the origin of the disease, what predisposes patients to develop the disorder, and discuss why all cases of ALS are not the same. In the 150 years since Charcot originally described ALS, painfully slow progress has been made towards answering these questions. We focus on what is known about ALS and where research is heading-from the small steps of extending longevity, improving therapies, undertaking clinical trials, and compiling population registries to the overarching goals of establishing the measures that guard against onset and finding the triggers for this neurodegenerative disorder.

Cortical excitability distinguishes ALS from mimic disorders

OBJECTIVE

The diagnosis of amyotrophic lateral sclerosis (ALS) relies on stringent clinical criteria, resulting in diagnostic delay and inevitably the institution of appropriate therapy. Cortical hyperexcitability, as assessed by the novel threshold tracking transcranial magnetic stimulation (TTTMS) technique, appears as an early feature of ALS. Consequently, the present study assessed the diagnostic utility of threshold tracking TMS and developed algorithms to aid the diagnosis of ALS.

METHODS

Prospective studies were undertaken on a cohort of 156 consecutive patients with neuromuscular symptoms (104 ALS and 52 lower motor neuron syndrome, non-ALS syndrome, NALS) and 62 healthy controls.

RESULTS

Short-interval intracortical inhibition (SICI) was significantly reduced in ALS patients (2.4 ± 0.9%) compared to NALS (8.7 ± 0.8%, P<0.0001) and controls (10.6 ± 0.8%, P < 0.0001). The MEP amplitude and intracortical facilitation were increased, while the cortical silent period duration was reduced in ALS, all indicative of cortical hyperexcitability. Analysis of receiver operating characteristic curves suggested that threshold tracking TMS distinguished ALS from NALS, with averaged (area under curve 0.76, P < 0.0001) and peak SICI 3 ms (area under curve 0.73, P<0.0001) being the most robust diagnostic markers.

CONCLUSIONS

The presence of cortical hyperexcitability distinguishes ALS from mimic disorders.

SIGNIFICANCE

The threshold tracking TMS techniques may prove useful as a diagnostic investigation for ALS.

Riluzole is a potent drug to protect neonatal rat hypoglossal motoneurons in vitro from excitotoxicity due to glutamate uptake block

Excitotoxic damage to motoneurons is thought to be an important contribution to the pathogenesis of amyotrophic lateral sclerosis (ALS), a slowly developing degeneration of motoneurons that, in most cases of sporadic occurrence, is associated with impaired glial glutamate uptake. Riluzole is the only drug licensed for symptomatic ALS treatment and is proposed to delay disease progression. As riluzole is administered only after full ALS manifestation, it is unclear if its early use might actually prevent motoneuron damage. We explored this issue by using, as a simple in vitro model, hypoglossal motoneurons (a primary target of ALS) of the neonatal rat brainstem slice preparation exposed to excitotoxic stress due to glutamate uptake block by DL-threo-β-benzyloxyaspartate (TBOA). TBOA evoked sustained network bursting, early (1 h) enhancement of the S100B immunostaining of gray matter astrocytes, and activated the motoneuronal stress ATF-3 transcription factor; 4 h later, loss (30%) of motoneuron staining ensued and pyknosis appeared. Riluzole (5 μM; applied 15 min after TBOA) inhibited bursting, decreased the frequency of spontaneous glutamatergic events, reversed changes in S100B immunostaining and prevented late loss of motoneuron staining. These results show that excitotoxicity induced by glutamate uptake block developed slowly, and was sensed by glia and motoneurons with delayed cell death. Our data provide novel evidence for the neuroprotective action of riluzole on motoneurons and glia when applied early after an excitotoxic stimulus.

Noninvasive detection of brainstem and spinal cord axonal degeneration in an amyotrophic lateral sclerosis mouse model

Degeneration of motor neurons and their associated axons is a hallmark of amyotrophic lateral sclerosis, but reliable noninvasive lesion detection is lacking. In vivo diffusion tensor imaging was performed to evaluate neurodegeneration in the brainstem and cervical spinal cord of wild-type and G93A-SOD1 transgenic mice, an animal model of amyotrophic lateral sclerosis. A statistically significant reduction in the apparent diffusion coefficient was observed in the motor nuclei VII and XII of G93A-SOD1 transgenic mice relative to wild-type mice. No significant difference in diffusion anisotropy was observed in dorsal white or gray matter in cervical and lumbar segments of the spinal cord. In contrast, statistically significant decreases in axial diffusivity (diffusivity parallel to the axis of the spinal cord) and apparent diffusion coefficient were found in the ventrolateral white matter of G93A-SOD1 mice in both the cervical and lumbar spinal cord. The reduction in axial diffusivity, suggestive of axonal injury, in the white matter of the spinal cord of G93A-SOD1 mice was verified by immunostaining with nonphosphorylated neurofilament. The present study demonstrates that in vivo diffusion tensor imaging-derived axial diffusivity may be used to accurately evaluate axonal degeneration in an animal model of amyotrophic lateral sclerosis.

Decreased stability and increased formation of soluble aggregates by immature superoxide dismutase do not account for disease severity in ALS

Protein aggregation is a hallmark of many diseases, including amyotrophic lateral sclerosis (ALS), where aggregation of Cu/Zn superoxide dismutase (SOD1) is implicated in causing neurodegeneration. Recent studies have suggested that destabilization and aggregation of the most immature form of SOD1, the disulfide-reduced, unmetallated (apo) protein is particularly important in causing ALS. We report herein in depth analyses of the effects of chemically and structurally diverse ALS-associated mutations on the stability and aggregation of reduced apo SOD1. In contrast with previous studies, we find that various reduced apo SOD1 mutants undergo highly reversible thermal denaturation with little aggregation, enabling quantitative thermodynamic stability analyses. In the absence of ALS-associated mutations, reduced apo SOD1 is marginally stable but predominantly folded. Mutations generally result in slight decreases to substantial increases in the fraction of unfolded protein. Calorimetry, ultracentrifugation, and light scattering show that all mutations enhance aggregation propensity, with the effects varying widely, from subtle increases in most cases, to pronounced formation of 40-100 nm soluble aggregates by A4V, a mutation that is associated with particularly short disease duration. Interestingly, although there is a correlation between observed aggregation and stability, there is minimal to no correlation between observed aggregation, predicted aggregation propensity, and disease characteristics. These findings suggest that reduced apo SOD1 does not play a dominant role in modulating disease. Rather, additional and/or multiple forms of SOD1 and additional biophysical and biological factors are needed to account for the toxicity of mutant SOD1 in ALS.

Neuroimaging in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a motor neuron disease characterized by progressive degeneration of upper motor neurons (UMN) and lower motor neurons (LMN). While LMN dysfunction can be confirmed by electromyography (EMG) and muscle biopsy, UMN involvement is more difficult to detect, particularly in the early phase. Objective and sensitive measures of UMN dysfunction are needed for early diagnosis and monitoring of disease progression and therapeutic efficacy. Advanced magnetic resonance imaging (MRI) techniques, such as diffusion, perfusion, magnetization transfer imaging, functional MRI, and MR spectroscopy, provide insight into the pathophysiological processes of ALS and may have a role in the identification and monitoring of UMN pathology. This article provides an overview of these neuroimaging techniques and their potential roles in ALS.

The epidemiology and treatment of ALS: focus on the heterogeneity of the disease and critical appraisal of therapeutic trials

Abstract Effective treatments for amyotrophic lateral sclerosis (ALS) have remained elusive. Only riluzole, a drug thought to affect glutamate metabolism, improves survival albeit to modest extent. Explanations for the negative results of therapeutic trials include a likely heterogeneity, both in disease susceptibility and pathogenic mechanisms, and faulty methodology of clinical trials. Further understanding of these factors will lead to improvements in patient stratification, and in the design of future clinical trials.

Reduced Interhemispheric Functional Connectivity in the Motor Cortex during Rest in Limb-Onset Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder of motor neurons that leads to paralysis and eventually death. There is evidence that atrophy occurs in the primary motor cortex (M1), but it is unclear how the disease affects the intrinsic connectivity of this structure. Thus, the goal of this study was to examine interhemispheric coupling of low frequency blood-oxygen-level dependent (BOLD) signal fluctuations in M1 using functional connectivity magnetic resonance imaging during rest. Because disease progression is rapid, high-functioning patients were recruited to assess neural changes in the relatively early stages of ALS. Twenty patients with limb-onset ALS participated in this study. A parceling technique was employed to segment both precentral gyri into multiple regions of interest (ROI), thus increasing sensitivity to detect changes that exist along discretely localized regions of the motor cortex. We report an overall systemic decrease in functional connectivity between right and left motor cortices in patients with limb-onset ALS. Additionally, we observed a pronounced disconnection between dorsal ROI pairs in the ALS group compared to the healthy control group. Furthermore, measures of limb functioning correlated with the connectivity data from dorsal ROI pairs in the ALS group, suggesting a symptomatic relationship with interhemispheric M1 connectivity.

Amyotrophic lateral sclerosis: current practice and future treatments

PURPOSE OF REVIEW

Knowledge of amyotrophic lateral sclerosis, and in particular the care of patients with it, is evolving exponentially. More than 1700 articles with the phrase 'amyotrophic lateral sclerosis' have been published in the past 2 years; these form the basis for this timely review.

RECENT FINDINGS

In part 1, I give an update on the care of patients with amyotrophic lateral sclerosis, including ways to speed diagnosis, optimal use of riluzole, multidisciplinary teams, mechanical ventilation, gastrostomy tubes, lipid-lowering agents and symptom management. Although care has become more evidence-based, there remain a number of quandaries; for these, I will provide suggestions based upon my own experience. In part 2, I identify some exciting new treatment options that are under study. These include agents designed for novel targets within motor neurons and nonneuronal cells, agents designed for specific amyotrophic lateral sclerosis subtypes and interesting new technologies. Finally, in part 3, I define current barriers to developing even better therapeutics and offer ways around them.

SUMMARY

The care of patients with amyotrophic lateral sclerosis has evolved and is now more evidence-based than ever before. Exciting new therapies are currently being tested, which may revolutionize care even further. Barriers exist, but they are surmountable.

Cystatin C: a candidate biomarker for amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal neurologic disease characterized by progressive motor neuron degeneration. Clinical disease management is hindered by both a lengthy diagnostic process and the absence of effective treatments. Reliable panels of diagnostic, surrogate, and prognostic biomarkers are needed to accelerate disease diagnosis and expedite drug development. The cysteine protease inhibitor cystatin C has recently gained interest as a candidate diagnostic biomarker for ALS, but further studies are required to fully characterize its biomarker utility. We used quantitative enzyme-linked immunosorbent assay (ELISA) to assess initial and longitudinal cerebrospinal fluid (CSF) and plasma cystatin C levels in 104 ALS patients and controls. Cystatin C levels in ALS patients were significantly elevated in plasma and reduced in CSF compared to healthy controls, but did not differ significantly from neurologic disease controls. In addition, the direction of longitudinal change in CSF cystatin C levels correlated to the rate of ALS disease progression, and initial CSF cystatin C levels were predictive of patient survival, suggesting that cystatin C may function as a surrogate marker of disease progression and survival. These data verify prior results for reduced cystatin C levels in the CSF of ALS patients, identify increased cystatin C levels in the plasma of ALS patients, and reveal correlations between CSF cystatin C levels to both ALS disease progression and patient survival.

Corpus callosum involvement is a consistent feature of amyotrophic lateral sclerosis

OBJECTIVE

While the hallmark of amyotrophic lateral sclerosis (ALS) is corticospinal tract in combination with lower motor neuron degeneration, the clinical involvement of both compartments is characteristically variable and the site of onset debated. We sought to establish whether there is a consistent signature of cerebral white matter abnormalities in heterogeneous ALS cases.

METHODS

In this observational study, diffusion tensor imaging was applied in a whole-brain analysis of 24 heterogeneous patients with ALS and well-matched healthy controls. Tract-based spatial statistics were used, with optimized voxel-based morphometry of T1 images to determine any associated gray matter involvement.

RESULTS

A consistent reduction in fractional anisotropy was demonstrated in the corpus callosum of the ALS group, extending rostrally and bilaterally to the region of the primary motor cortices, independent of the degree of clinical upper motor neuron involvement. Matched regional radial diffusivity increase supported the concept of anterograde degeneration of callosal fibers observed pathologically. Gray matter reductions were observed bilaterally in primary motor and supplementary motor regions, and also in the anterior cingulate and temporal lobe regions. A post hoc group comparison model incorporating significant values for fractional anisotropy, radial diffusivity, and gray matter was 92% sensitive, 88% specific, with an accuracy of 90%.

CONCLUSION

Callosal involvement is a consistent feature of ALS, independent of clinical upper motor neuron involvement, and may reflect independent bilateral cortical involvement or interhemispheric spread of pathology. The predominantly rostral corticospinal tract involvement further supports the concept of independent cortical degeneration even in those patients with ALS with predominantly lower motor neuron involvement clinically.

IL-17A is increased in the serum and in spinal cord CD8 and mast cells of ALS patients

The contribution of inflammation to neurodegenerative diseases is increasingly recognized, but the role of inflammation in sporadic amyotrophic lateral sclerosis (sALS) is not well understood and no animal model is available. We used enzyme-linked immunosorbent assays (ELISAs) to measure the cytokine interleukin-17A (IL-17A) in the serum of ALS patients (n = 32; 28 sporadic ALS (sALS) and 4 familial ALS (fALS)) and control subjects (n = 14; 10 healthy subjects and 4 with autoimmune disorders). IL-17A serum concentrations were 5767 ± 2700 pg/ml (mean ± SEM) in sALS patients and 937 ± 927 pg/ml in fALS patients in comparison to 7 ± 2 pg/ml in control subjects without autoimmune disorders (p = 0.008 ALS patients vs. control subjects by Mann-Whitney test). Sixty-four percent of patients and no control subjects had IL-17A serum concentrations > 50 pg/ml (p = 0.003 ALS patients vs. healthy subjects by Fisher's exact test). The spinal cords of sALS (n = 8), but not control subjects (n = 4), were infiltrated by interleukin-1β- (IL-1β-), and tumor necrosis factor-α-positive macrophages (co-localizing with neurons), IL-17A-positive CD8 cells, and IL-17A-positive mast cells. Mononuclear cells treated with aggregated forms of wild type superoxide dismutase-1 (SOD-1) showed induction of the cytokines IL-1β, interleukin-6 (IL-6), and interleukin-23 (IL-23) that may be responsible for induction of IL-17A. In a microarray analysis of 28,869 genes, stimulation of peripheral blood mononuclear cells by mutant superoxide dismutase-1 induced four-fold higher transcripts of interleukin-1α (IL-1α), IL-6, CCL20, matrix metallopeptidase 1, and tissue factor pathway inhibitor 2 in mononuclear cells of patients as compared to controls, whereas the anti-inflammatory cytokine interleukin-10 (IL-10) was increased in mononuclear cells of control subjects. Aggregated wild type SOD-1 in sALS neurons could induce in mononuclear cells the cytokines inducing chronic inflammation in sALS spinal cord, in particular IL-6 and IL-17A, damaging neurons. Immune modulation of chronic inflammation may be a new approach to sALS.

Advances in the application of MRI to amyotrophic lateral sclerosis

IMPORTANCE OF THE FIELD: With the emergence of therapeutic candidates for the incurable and rapidly progressive neurodegenerative condition of amyotrophic lateral sclerosis (ALS), it will be essential to develop easily obtainable biomarkers for diagnosis, as well as monitoring, in a disease where clinical examination remains the predominant diagnostic tool. Magnetic resonance imaging (MRI) has greatly developed over the past thirty years since its initial introduction to neuroscience. With multi-modal applications, MRI is now offering exciting opportunities to develop practical biomarkers in ALS. AREAS COVERED IN THIS REVIEW: The historical application of MRI to the field of ALS, its state-of-the-art and future aspirations will be reviewed. Specifically, the significance and limitations of structural MRI to detect gross morphological tissue changes in relation to clinical presentation will be discussed. The more recent application of diffusion tensor imaging (DTI), magnetic resonance spectroscopy (MRS), functional and resting-state MRI (fMRI & R-fMRI) will be contrasted in relation to these more conventional MRI assessments. Finally, future aspirations will be sketched out in providing a more disease mechanism-based molecular MRI. WHAT THE READER WILL GAIN: This review will equip the reader with an overview of the application of MRI to ALS and illustrate its potential to develop biomarkers. This discussion is exemplified by key studies, demonstrating the strengths and limitations of each modality. The reader will gain an expert opinion on both the current and future developments of MR imaging in ALS. TAKE HOME MESSAGE: MR imaging generates potential diagnostic, prognostic and therapeutic monitoring biomarkers of ALS. The emerging fusion of structural, functional and potentially molecular imaging will improve our understanding of wider cerebral connectivity and holds the promise of biomarkers sensitive to the earliest changes.

Interaction between aging and neurodegeneration in amyotrophic lateral sclerosis

We assessed the spontaneous blood-oxygen-level-dependent signal fluctuations in the resting-state brain networks of amyotrophic lateral sclerosis patients and their relation to physiologically sensitive and disease modified functional magnetic resonance imaging parameters. Resting-state functional magnetic resonance imaging was performed at 3 Tesla on 20 amyotrophic lateral sclerosis patients with minimal frontal cognitive dysfunction and 20 age- and sex-matched healthy volunteers. Resting-state network maps were extracted with independent component analysis and group-level statistical analyses were performed to detect disease and disease-by-age interaction effects. Whole-brain global and regional atrophy measures were obtained from same-session structural scans. The sensori-motor network showed significant disease effects, with signals suppressed in patients bilaterally in the primary motor cortex. The default-mode network showed a significant disease-by-age interaction in the posterior cingulate cortex, where signals correlated with age positively in patients and negatively in controls. Both disease and disease-by-age interaction effects were detected in the right fronto-parietal network. Although global atrophy did not show significant differences, regions of reduced gray matter volume were detected in patients compared with controls adjacent to regions of reduced functional connectivity. Our results confirm that resting-state functional magnetic resonance imaging signals in the sensori-motor network are suppressed in amyotrophic lateral sclerosis. A similar suppression is evident in the right fronto-parietal network, possibly reflecting the patients' frontal dysfunction and right-lateralized patterns of regional atrophy. The interaction between disease and aging in the default-mode network unravels a possible mechanism of compensation between motor and extramotor systems emerging as a supplementary functional push to help motor disturbances.

Corticospinal tract dysfunction and development of amyotrophic lateral sclerosis following electrical injury

The causal relationship between electrical injury and development of amyotrophic lateral sclerosis (ALS) remains controversial. We describe the case of a 25-year-old man who developed ALS after a severe electrical injury. Cerebral magnetic resonance imaging (MRI) demonstrated hyperintensities involving the corticospinal tract. Functional testing with transcranial magnetic stimulation established that the motor cortex was relatively inexcitable. In addition, there were features of denervation on electromyography and muscle biopsy that supported concomitant lower motor neuron findings and the diagnosis of ALS.

Integrative gene-tissue microarray-based approach for identification of human disease biomarkers: application to amyotrophic lateral sclerosis

Advances in genomics and proteomics permit rapid identification of disease-relevant genes and proteins. Challenges include biological differences between animal models and human diseases, high discordance between DNA and protein expression data and a lack of experimental models to study human complex diseases. To overcome some of these limitations, we developed an integrative approach using animal models, postmortem human material and a combination of high-throughput microarray methods to identify novel molecular markers of amyotrophic lateral sclerosis (ALS). We used laser capture microdissection coupled with microarrays to identify early transcriptome changes occurring in spinal cord motor neurons or surrounding glial cells. Two models of familial motor neuron disease, SOD1(G93A) and TAU(P301L), transgenic mice were used at the presymptomatic stage. Identified gene expression changes were predominantly model-specific. However, several genes were regulated in both models. The relevance of identified genes as clinical biomarkers was tested in the peripheral blood transcriptome of presymptomatic SOD1(G93A) animals using custom-designed ALS microarray. To confirm the relevance of identified genes in human sporadic ALS (SALS), selected corresponding protein products were examined by high-throughput immunoassays using tissue microarrays constructed from human postmortem spinal cord tissues. Genes that were identified by these experiments and located within a linkage region associated with familial ALS/frontotemporal dementia were sequenced in several families. This large-scale gene and protein expression study pointing to distinct molecular mechanisms of TAU- and SOD1-induced motor neuron degeneration identified several new SALS-relevant proteins (CNGA3, CRB1, OTUB2, MMP14, SLK, DDX58, RSPO2) and putative blood biomarkers, including Nefh, Prph and Mgll.

The application of biomarkers in clinical trials for motor neuron disease

The interest and research into disease-related biomarkers has greatly accelerated over the last 10 years. The potential clinical benefits for disease-specific biomarkers include a more rapid and accurate disease diagnosis, and potential reduction in size and duration of clinical drug trials, which would speed up drug development. The application of biomarkers into the clinical arena of motor neuron disease should both determine if a drug hits its proposed target and whether the drug alters the course of disease. This article will highlight the progress made in discovering suitable biomarker candidates from a variety of sources, including imaging, neurophysiology and proteomics. For biomarkers to have clinical utility, specific criteria must be satisfied. While there has been tremendous effort to discover biomarkers, very few have been translated to the clinic. The bottlenecks in the biomarker pipeline will be highlighted as well as lessons that can be learned from other disciplines, such as oncology.

Modulation of inflammation by chondroitin sulfate

OBJECTIVE AND METHODS

To evaluate the immune-modulator effect of chondroitin sulfate (CS) by means of the review of the literature.

RESULTS

Inflammatory reactions are primarily originated by infectious agents, immune reactions and by sterile tissue lesions that activate membrane receptors by means of pathogen-associated molecular patterns, tissue breakdown products and cytokines. The activation of membrane receptors triggers the phosphorylation of mitogen activated protein kinases and of the nuclear factor kappaB (NF-kappaB). The binding of NF-kappaB to the promoter of target genes enhances the expression of pro-inflammatory cytokines, inducible nitric oxide synthase, cyclooxygenase 2, phospholipase A2, and matrix metalloproteases, proteins that contribute to tissue damage and to the inflammatory reaction. The activation of NF-kappaB has a key role in the immune homeostasis and the inflammatory response and therefore, in the pathogenesis of numerous diseases. Chondroitin sulfate (CS) is able to diminish NF-kappaB activation and nuclear translocation in chondrocytes and synovial membrane, effects that may explain the benefits of CS in osteoarthritis. In addition, systemic CS reduces NF-kappaB nuclear translocation in macrophages and hepatocytes, raising the hypothesis that CS might be of benefit to treat other diseases with a strong inflammatory component. There is preliminary evidence in humans that CS improves moderate to severe psoriasis. Moreover, experimental and clinical data suggest that CS might be a useful therapeutic agent in diseases such as inflammatory bowel diseases, atherosclerosis, Parkinson's and Alzheimer's diseases, multiple sclerosis, amyotrophic lateral sclerosis, rheumatoid arthritis and systemic lupus erythematosus.

DISCUSSION

These results urge for double blinded placebo-controlled trials to confirm the utility of CS in diseases with immune and inflammatory components.

[Research in amyotrophic lateral sclerosis: what is new in 2009?]

This paper, written by French amyotrophic lateral sclerosis (ALS) center experts, presents an update of recent advances in fundamental, epidemiological and clinical research in ALS based on a review of the literature between September 2008 and November 2009. Among other pathophysiological mechanisms, the role of stress of the endoplasmic reticulum and the importance of energetic metabolic disturbances have been underscored. In the field of genetics, research has been advanced through the identification of mutations of the gene FUsed in Sarcoma/Translated in LipoSarcoma (FUS/TLS) in individuals with familial and sporadic ALS. This gene is involved in the regulation of transcription, splicing and RNA transport, and has functional homology to another ALS gene, TARDBP, which suggests that a common mechanism may underlie motor neuron degeneration. A report showed that mice expressing a mutant form of human TDP-43 develop a progressive and fatal neurodegenerative disease reminiscent of both ALS and frontotemporal lobar degeneration with ubiquitin aggregates (FTLD-U), providing a new animal model that may help to better understand the pathophysiology and test new therapeutics. Beside genetic studies, several epidemiologic studies have investigated the role of environmental factors. A recent study suggests that smoking is a risk factor for developing ALS and it is hypothesized that this could occur through lipid peroxidation via formaldehyde exposure. From a neuroprotective perspective, trials with IGF-1, sodium valproate, coenzyme Q or glatiramer acetate have failed to demonstrate any beneficial effect. A study published in 2008 argued that lithium may have a neuroprotective effect in ALS mice and also in patients. However, two preclinical studies failed to replicate the neuroprotective effect of lithium in ALS mice. Therapeutic trials have been performed or are currently ongoing in Europe and North America. Their results have not yet been published.

Assessment of white matter tract damage in patients with amyotrophic lateral sclerosis: a diffusion tensor MR imaging tractography study

BACKGROUND AND PURPOSE

Most DTI studies in ALS have been limited to the assessment of the CST damage. In this study, we used DTI tractography to investigate whether microstructural abnormalities occur in the major motor and extramotor WM tracts in mildly disabled patients with ALS.

MATERIALS AND METHODS

Brain conventional MR imaging and DTI were performed in 24 patients with probable or definite ALS and mild disability (ALSFRS score, ≥20) and 20 healthy controls. The mean disease progression rate was 0.62 (range = 0.08-2.50). DTI tractography was used to segment the CST, the corpus callosum, and the major WM association tracts (ie, cingulum, uncinate fasciculus, inferior fronto-occipital, inferior longitudinal, and superior longitudinal fasciculi).

RESULTS

Compared with healthy controls, patients with ALS showed significantly decreased FA and significantly increased MD and radial D of the CST bilaterally (P values from .005 to .01). Patients with ALS also had a significantly increased axial D of the right uncinate fasciculus relative to controls (P = .04). CST FA significantly correlated with the rate of disease progression (right CST: r = -0.50, P = .02; left CST: r = -0.41, P = .05).

CONCLUSIONS

Patients with ALS and mild disability have preferential damage to the CST. The association of CST damage with the rate of disease progression suggests that DTI has the potential to provide in vivo markers of ALS evolution. The subtle involvement of the uncinate fasciculus may precede the appearance of behavioral symptoms in patients with ALS.