Biomarkers for amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a relentlessly progressive neurodegenerative disorder. Modern technology has brought new insights in the underlying pathophysiology of ALS through examination of genomic, proteomic and physiological changes in patients. However, the diagnosis of this disorder is still based on clinical findings, and there is a pronounced delay between the onset of symptoms and diagnosis. Functional rating scales, forced vital capacity, and patient survival have been used as measures of therapeutic response so far. Although effective treatments for ALS are lacking, the discovery of biomarkers for this disease offers clinicians the tools for rapid diagnosis, improved ways to monitor disease progression, and insights into the pathophysiology of sporadic ALS. Potential biomarkers that are useful in the diagnosis of ALS and sensitive to the progression of disease, which might enhance the diagnostic algorithm and provide new drug targets, are now being eagerly investigated through blood and cerebrospinal fluid analyses, as well as physiological and neuroimaging studies. These biomarkers, when used in combination, might be sensitive to early therapeutic effects. Such biomarkers might also resolve complexities of phenotypic heterogeneity in clinical trials. In this review article, I have discussed the development of biochemical, physiological and neuroimaging biomarkers for ALS including our recent results on CSF TDP-43 (TAR DNA-binding protein 43 kDa), and have considered the potential future directions for research. We should ultimately aim to broaden the available therapeutic options for patients with this disease.     

质子磁共振波谱在肌萎缩侧索硬化的诊断及其用力如太治疗中应用探讨

目的:探讨~1H-MRS在ALS患者的临床应用价值。方法:对34例ALS病人双侧大脑中央前回进行质子波谱分析,同时进行临床量表评分,并随访其中进行治疗的24例病例。治疗组分两组:力如太组(力如太50 mg bid)和免疫治疗组(环磷酰胺和地塞米松)。结果:①NAA/Cr比值在ALS病人上显著降低,P<0.01;②力如太治疗最初的1个月,NAA/Cr比值上升,P<0.05,而免疫治疗组(环磷酰胺+地塞米松)无此变化;③NAA/Cr的改善与力如太组在Appel延髓评分的改善相一致,且NAA/Cr比值更为敏感。结论:~1H-MRS中的NAA/Cr比值可以作为大脑中央前回运动神经元受损的指标,并且也可用来客观地监测疾病的进展,观察药效。     

Early detection and longitudinal changes in amyotrophic lateral sclerosis by (1)H MRSI

OBJECTIVE: To determine 1) the reproducibility of metabolite measurements by (1)H MRS in the motor cortex; 2) the extent to which (1)H MRS imaging (MRSI) detects abnormal concentrations of N-acetylaspartate (NAA)-, choline (Cho)-, and creatine (Cre)-containing compounds in early stages of ALS; and 3) the metabolite changes over time in ALS. METHODS: Sixteen patients with definite or probable ALS, 12 with possible or suspected ALS, and 12 healthy controls underwent structural MRI and multislice (1)H MRSI. (1)H MRSI data were coregistered with tissue-segmented MRI data to obtain concentrations of NAA, Cre, and Cho in the left and right motor cortex and in gray matter and white matter of nonmotor regions in the brain. RESULTS: The interclass correlation coefficient of NAA was 0.53 in the motor cortex tissue and 0.83 in nonmotor cortex tissue. When cross-sectional data for patients were compared with those for controls, the NAA/(Cre + Cho) ratio in the motor cortex region was significantly reduced, primarily due to increases in Cre and Cho and a decrease in NAA concentrations. A similar, although not significant, trend of increased Cho and Cre and reduced NAA levels was also observed for patients with possible or suspected ALS. Furthermore, in longitudinal studies, decreases in NAA, Cre, and Cho concentrations were detected in motor cortex but not in nonmotor regions in ALS. CONCLUSION: Metabolite changes measured by (1)H MRSI may provide a surrogate marker of ALS that can aid detection of early disease and monitor progression and treatment response.     

High content analysis in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating disease characterized by the progressive loss of motor neurons. Neurons, astrocytes, oligodendrocytes and microglial cells all undergo pathological modifications in the onset and progression of ALS. A number of genes involved in the etiopathology of the disease have been identified, but a complete understanding of the molecular mechanisms of ALS has yet to be determined. Currently, people affected by ALS have a life expectancy of only two to five years from diagnosis. The search for a treatment has been slow and mostly unsuccessful, leaving patients in desperate need of better therapies. Until recently, most pre-clinical studies utilized the available ALS animal models. In the past years, the development of new protocols for isolation of patient cells and differentiation into relevant cell types has provided new tools to model ALS, potentially more relevant to the disease itself as they directly come from patients. The use of stem cells is showing promise to facilitate ALS research by expanding our understanding of the disease and help to identify potential new therapeutic targets and therapies to help patients. Advancements in high content analysis (HCA) have the power to contribute to move ALS research forward by combining automated image acquisition along with digital image analysis. With modern HCA machines it is possible, in a period of just a few hours, to observe changes in morphology and survival of cells, under the stimulation of hundreds, if not thousands of drugs and compounds. In this article, we will summarize the major molecular and cellular hallmarks of ALS, describe the advancements provided by the in vitro models developed in the last few years, and review the studies that have applied HCA to the ALS field to date.     

Investigation of white matter pathology in ALS and PLS using tract-based spatial statistics

OBJECTIVE: We aimed to investigate differences in fractional anisotropy (FA) between primary lateral sclerosis (PLS) and amyotrophic lateral sclerosis (ALS) and the relationship between FA and disease progression using tract-based spatial statistics (TBSS). METHODS: Two scanners at two different sites were used. Differences in FA between ALS patients and controls scanned in London were investigated. From the results of this analysis, brain regions were selected to test for (i) differences in FA between controls, patients with ALS and patients with PLS scanned in Oxford and (ii) the relationship between FA and disease progression rate in the Oxford patient groups. RESULTS: London ALS patients showed a lower FA than controls in several brain regions. Oxford patients with PLS showed a lower FA than ALS patients and than controls in the body of the corpus callosum and in the white matter adjacent to the right primary motor cortex (PMC), while ALS patients showed reduced FA compared with PLS patients in the white matter adjacent to the superior frontal gyrus. Significant correlations were found between disease progression rate and (i) FA in the white matter adjacent to the PMC in PLS, and (ii) FA along the cortico-spinal tract and in the body of the corpus callosum in ALS. CONCLUSIONS: We described significant FA changes between PLS and ALS, suggesting that these two presentations of motor neuron disease show different features. The significant correlation between FA and disease progression rate in PLS suggests the tissue damage reflected in FA changes contributes to the disease progression rate.     

Cognition and amyotrophic lateral sclerosis (ALS)

Amyotrophic lateral sclerosis (ALS) is classically described as a pure motor disease; however, there is growing evidence of a range of cognitive impairment. Cognitive abnormalities include deficiencies in frontal executive skills, varying from mild deficits to meeting criteria for diagnosis of frontotemporal dementia (FTD). Cognitive impairment occurs in sporadic and familial forms of ALS. Patients may present with cognitive deficits before, after, or at the onset of motor neuron disease. Structural and functional imaging studies have shown extramotor cortical degeneration corresponding to levels of frontal executive impairment on neuropsychologic testing. In addition, ALS and a subset of FTD patients display common pathological findings on immunohistochemistry staining. It is believed that these disorders represent a continuum between motor and nonmotor cortical degeneration. The purpose of this article is to review the literature on cognitive deficits in ALS. Identifying changes in cognition is critical for physicians and caregivers of ALS patients, as cognitive decline may interfere with patient compliance. Diagnosis and treatment of cognitive symptoms in ALS patients may improve quality of life.     

Molecular link between inefficient GluA2 RNA editing and TDP-43 pathology in ALS motor neurons

The motor neurons of sporadic amyotrophic lateral sclerosis (ALS) patients exhibit several molecular abnormalities, including 2 that are specific to ALS motor neurons: (1) pathological changes related to the mislocalization of the TAR DNA-binding protein (TDP-43), including both the appearance of phosphorylated TDP-43-containing inclusions in the cytoplasm and the loss of TDP-43 from the nucleus; and (2) inefficient RNA editing at the Q/R site of GluA2, a subunit of the AMPA receptor. TDP-43-related pathological features are closely associated with ALS in most ALS patients and with significant behavioral and pathological changes in genetically engineered mice; therefore, abnormal TDP-43 processing is believed to play a role in the pathogenesis of ALS. The extent of GluA2 RNA editing decreases in the motor neurons of sporadic ALS patients in a disease-specific and motor neuron-selective manner. Importantly, this molecular abnormality is a direct cause of death of motor neurons in conditional knockout mice for adenosine deaminase acting on RNA 2 (ADAR2), the enzyme that specifically catalyzes RNA editing at the GluA2 Q/R site. Notably, these molecular abnormalities, i.e., TDP-43-related pathological features and inefficient GluA2 RNA editing, are found in approximately half of the motor neurons in sporadic ALS patients and both of them always occur in the same motor neurons. Because TDP-43-related pathological features and inefficient GluA2 RNA editing are highly disease specific in ALS motor neurons, investigation into the molecular link between these abnormalities is likely to provide new insights into ALS pathogenesis.     

Respiratory function in amyotrophic lateral sclerosis

Abstract. The aim of this study was to examine the vital capacity (FVC) and forced expiratory volume in 1 s (FEV 1) in relation to the site of amyotrophic lateral sclerosis (ALS) onset and the duration of the disease. Respiratory involvement is the principal cause of death in ALS patients. The study was conducted at the Department of Neurology, University School of Medicine in Lublin. The study comprised 18 ALS patients. The average duration of ALS was 12 months. The patients were divided into two groups according to the site of ALS onset and into two groups according to the duration of the disease. FVC was significantly higher in the group of patients with a limb onset than in the group of patients with a bulbar onset of the disease. The study has shown respiratory function disturbances in ALS patients. FVC significantly depends on the site of ALS onset but not on the duration of the disease.     

胸段脊旁肌肌电图在肌萎缩侧索硬化诊断中的作用

目的 研究胸段脊旁肌自发电位在诊断肌萎缩侧索硬化(amyotrophic lateral sclerosis，ALS)中的价值。方法 50例确诊的ALS患者分别行胸段脊旁肌自发电位、胸锁乳突肌运动单位，部分患者行舌肌自发电位检测；同时，将性别、年龄相匹配的30例根性损害的患者和30名健康人作为对照，行胸段脊旁肌自发电位检测。结果 50例ALS患者中，41例(82％)胸段脊旁肌肌电图可见大量纤颤电位和正锐波；胸锁乳突肌肌电图无一例见自发电位，但有48例(96%)运动单位时限增宽，波幅增高，符合慢性神经源性损害改变；6例患者行舌肌自发电位检测，3例可见自发电位。30例根性病变的患者中，2例(7％)可见胸段脊旁肌有少量自发电位；健康对照组未见胸段脊旁肌自发电位。结论 胸段脊旁肌大量自发电位对诊断ALS具有一定的敏感性。     

Emotional adjustment in amyotrophic lateral sclerosis (ALS)

Despite the devastating motor impairment, a significant number of patients with amyotrophic lateral sclerosis (ALS) maintain a good psychosocial adjustment. Here we investigated whether this is specific for ALS or a more general characteristic of terminal disease. Psychosocial adjustment was investigated in 30 ALS patients, 29 cancer patients in palliative treatment and 29 age-, gender- and level of education-matched healthy controls. Subjective quality of life (sQoL), degree of depressive symptoms and coping were evaluated as measures of psychosocial adjustment. Personality factors were described. ALS and cancer patients showed a good psychosocial adjustment. Subjective QoL and depression did not differ significantly. Both patient groups presented a good sQoL. The level of mild depressive symptoms in both patient groups was similar and none showed clinically relevant depression. ALS patients expressed fewer active coping strategies than cancer patients which were explained by gender differences. Both patient groups showed comparable psychosocial adjustment to their disease. Overall, in terminally ill patients the psychological response to the prognosis is not associated with neurobiological changes (e.g., associated with subclinical deficits in ALS) or with physical decline.     

Changes in cortically induced inhibition in amyotrophic lateral sclerosis with time

Changes in intracortical inhibition have been detected by means of paired‐pulse transcranial magnetic stimulation (TMS) based on electromyographic recordings in many neurological or psychiatric disorders, including amyotrophic lateral sclerosis (ALS). By contrast, inhibitory responses have been generally overlooked in single motor unit (MU) studies in patients with ALS. The aim of this study was to investigate the TMS‐induced inhibitory responses of single MUs in peristimulus time histograms and the changes observed with time. For this purpose, 263 MUs were tested in 10 ALS patients in two to four recording sessions. Upon subdividing the data into epochs corresponding to mean disease durations of 12, 20, 32, 43, and 168 months, we found that inhibitory responses occurred more frequently than normal throughout the course of the disease and were stronger than normal during the first year after disease onset. This finding argues against the hypothesis that loss of inhibition may be part of the pathogenic process in ALS. Muscle Nerve 39: 310–317, 2009     

Mesenchymal stem cell transplantation in amyotrophic lateral sclerosis: A Phase I clinical trial

Amyotrophic Lateral Sclerosis (ALS) is a devastating incurable disease. Stem-cell-based therapies represent a new possible strategy for ALS clinical research. The objectives of this Phase 1 clinical study were to assess the feasibility and toxicity of mesenchymal stem cell transplantation and to test the impact of a cell therapy in ALS patients. The trial was approved and monitored by the National Institute of Health and by the Ethics Committees of all participating Institutions. Autologous MSCs were isolated from bone marrow, expanded in vitro and analyzed according to GMP conditions. Expanded MSCs were suspended in the autologous cerebrospinal fluid (CSF) and directly transplanted into the spinal cord at a high thoracic level with a surgical procedure. Ten ALS patients were enrolled and regularly monitored before and after transplantation by clinical, psychological, neuroradiological and neurophysiological assessments. There was no immediate or delayed transplant-related toxicity. Clinical, laboratory, and radiographic evaluations of the patients showed no serious transplant-related adverse events. Magnetic resonance images (MRI) showed no structural changes (including tumor formation) in either the brain or the spinal cord. However the lack of post mortem material prevents any definitive conclusion about the vitality of the MSCs after transplantation. In conclusion, this study confirms that MSC transplantation into the spinal cord of ALS patients is safe and that MSCs might have a clinical use for future ALS cell based clinical trials.     

Comorbidity between migraine and depression: update on traditional and alternative treatments

Amyotrophic lateral sclerosis (ALS) is generally considered to be a paradigm of pure motor neuron disorder; nevertheless, the possible occurrence of cognitive impairment up to a frank dementia in patients affected by ALS is recognized. The appraisal of the cognitive impairment in ALS patients is crucial not only to the therapeutic trials of this incurable disease, but also to the planning of care, compliance to interventions, the end-of-life decisions. The cognitive/behavioral changes of ALS patients are consistent with frontotemporal dysfunctions; the overlap of neuropathological features of ALS and frontotemporal lobe degeneration (FTLD) supports, in addition, the putative spectrum of ALS and FTD. In the present review, the pertinent clinical, genetic, neuropathological, neuropsychological and neuroimaging data of the literature are comprehensively and critically discussed. The distinct and overlapping features of ALS and FTD are pointed out, as well as the undisclosed questions deserving additional studies.     

Symptomatic treatment of respiratory and nutritional failure in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterised by death of upper and lower motor neurones. Nutritional and respiratory failure occurs in most patients with ALS. Nutritional failure occurs primarily as a result of dysphagia, although malnutrition may also develop in the absence of clinically apparent dysphagia. The optimal management of nutrition in early ALS has not been established. In later stages of the disease, parenteral nutritional support using percutaneous endoscopic gastrostomy confers a significant survival benefit in selected patients. Respiratory failure occurs as a result of bulbar, cervical and thoracic loss of motor neurones. Inspiratory muscles are preferentially affected. Management of respiratory failure includes the use of strategies that limit aspiration pneumonia, the reduction in secretions, and positioning of the patient to a maximal mechanical advantage. Use of non-invasive positive pressure ventilation in appropriate patients significantly enhances survival. The decision to undertake invasive mechanical ventilation should be made prior to the development of symptoms that might warrant this intervention. The progressive nature of the condition should be taken into account when such a decision is discussed with the patient and carer. Further studies are required to determine the optimal nutritional requirements of patients with ALS, and to elucidate the physiological changes involved in the decline in respiratory function. Received: 13 September 1999/Accepted: 1 October 1999     

Motor unit number estimates and quantitative motor unit analysis in healthy subjects and patients with amyotrophic lateral sclerosis

Limitations associated with global measures of function in patients with amyotrophic lateral sclerosis (ALS) and the qualitative nature of needle electromyography have stimulated the development of alternate means of monitoring disease severity and progression in ALS. Thus, the objective of this study was to examine the ability of one these techniques, decomposition-based quantitative electromyography (DQEMG), to obtain electrophysiological data, including motor unit number estimates (MUNEs), from a group of patients with ALS. The first dorsal interosseous and biceps brachii muscles were studied in 10 healthy subjects and 9 patients with ALS. Following the acquisition of a maximum M wave, needle- and surface-detected EMGs were collected simultaneously during 30-second contractions performed at 10% of the maximum voluntary contraction force to obtain motor unit potential (MUP) trains. DQEMG was then used to extract the surface-detected MUP associated with each MUP train, the mean size of which was divided into the maximum M wave to obtain a MUNE. The results suggest that quantitative electrophysiological data obtained using DQEMG are representative of the pathophysiological changes in the lower motor system in ALS patients, supporting its use in studies documenting the natural history and progression of the disease.     

Amino acids acting as transmitters in amyotrophic lateral sclerosis (ALS)

Objectives - In amyotrophic lateral sclerosis (ALS), a neurodegenerative disease of unknown origin, excitotoxic mechanisms are supposed to be involved. Divergent results are, however, presented either because of the heterogeneity of this disease, and/or different methodologies used to evaluate the excitotoxic amino acids content. The results of the most sensitive high performance liquid chromatography (HPLC) techniques with precolumn derivatization of fasting serum and CSF glutamate, aspartate, glycine and γ-aminobutyric acid (GABA) in mild and severely progressing ALS cases are presented here. Material and methods - We studied 25 ALS patients with different course of the disease and controls, which consisted of 10 cases with other motor neuron diseases and 20 healthy, age-matched subjects. Results - In the ALS patients with a mild course of the disease serum glutamate and aspartate content was either normal or slightly decreased, in all of these cases a rise in GABA and glycine was present. In the severely progressing ALS cases serum glutamate and aspartate was increased. The GABA content was either normal or increased, the glycine level appeared to be either normal or decreased. In CSF the amino acids changes in ALS were less pronounced as compared to serum. The most frequent finding was the increase in GABA concentration both in the mild and the severely progressing group. CSF glutamate in ALS patients with mild course of the disease was decreased, in the severely progressing cases the glutamate level appeared in a broad range from decreased to increased values. CSF aspartate was either normal or elevated, glycine values were present in a broad range from decreased to increased values. In the other tested motor neuron diseases no consistent changes in serum and CSF amino acids concentration was observed. Conclusions - The data from serum and CSF indicate that in ALS an imbalance between excitatory and inhibitory amino acids might be present in the brain, which may be induced in different ways in particular ALS patients. It may be an important factor for the mediation of neurons death.     

Continuum of frontal lobe impairment in amyotrophic lateral sclerosis

OBJECTIVE: To identify the nature and prevalence of cognitive and behavioral abnormalities in patients with amyotrophic lateral sclerosis (ALS). DESIGN: Survey of clinical characteristics. SETTING: Multidisciplinary clinic within a university medical center. Patients A volunteer sample of 30 new patients with ALS were recruited consecutively. Of those invited, 23 participants (20 with sporadic ALS and 3 with familial ALS) enrolled. Participants ranged in age from 27 to 80 years (mean age, 56.5 years); the education level ranged from 12 to 21 years (mean education level, 3.5 years of college); and 17 participants (74%) were male. MAIN OUTCOME MEASURES: Neuropsychological tests, neurobehavioral interviews, and structured magnetic resonance imaging. RESULTS: Patients were classified into subtypes of frontotemporal lobar degeneration (n = 5), suspected Alzheimer disease (n = 1), and subthreshold variants of cognitive impairment (n = 2), behavioral impairment (n = 4), and cognitively and behaviorally normal (n = 11). Five neuropsychological tests, 2 behavioral abnormalities, and right hemisphere gray matter reductions differentiated patients into normal and abnormal groups. CONCLUSIONS: In this sample, a sizable proportion of patients with ALS possess a range of behavioral and cognitive changes that lie on a spectrum of frontotemporal impairment. Right hemisphere atrophy may be a biomarker for cognitive impairment in patients with ALS.     

Genetic determinants of amyotrophic lateral sclerosis as therapeutic targets

Amyotrophic lateral sclerosis (ALS) is an incurable disease resulting from the deterioration of motor neurons. The onset of disease typically occurs in the fifth decade of life and progresses rapidly; death occurs for 75% of patients within 5 years. The only drug that is available to treat ALS is riluzole, which extends survival by just 2-3 months. Thus, new therapeutic directions are being sought to prolong the lifespan of ALS patients. Since the discovery of SOD1 as a genetic determinant of ALS in 1993, SOD1-models of ALS have been extensively employed for the development of ALS therapeutics. Novel genetic targets are now under investigation following the recent discoveries linking TDP-43, FUS/TLS, angiogenin, KIFAP3 and UNC13A to ALS. In this review, we present several of the genetic contributors to both sporadic and familial forms of ALS and discuss their potential as therapeutic targets for this devastating disease.     

Emotional responding in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal disease, leaving the patient in a partially or completely deafferented state. In an explorative study, we investigated responses to visual socio–emotional stimuli in ALS patients. Pictures from the International Affective Picture System (IAPS) were verbally judged by 12 moderately affected ALS patients with a spinal onset and a slow progression and 18 age–matched controls, and data were compared with psychophysiological responses. Verbal emotional judgments of patients were more positive than ratings of controls. Regarding arousal, patients neutralized extreme pictures, in that they rated calm pictures as more exciting than controls and exciting pictures as more calm. These changes of emotional processing were unrelated to depression or frontal lobe dysfunction. There were no major differences between patients and controls concerning physiological responses to emotional stimuli. We conclude that emotional responses of ALS patients tend to be altered towards positive valence and towards a more balanced arousal state in early stages of the disease. These findings contradict assumptions of a generally negative impact of the disease on the emotional disposition and may indicate compensatory cognitive or neuroplastic changes.     

Amyotrophic lateral sclerosis IgG-treated neuromuscular junctions develop sensitivity to L-type calcium channel blocker

In order to search for early changes induced by the application of human immunoglobulin G (IgG) on motor nerve terminals, IgG from patients with amyotrophic lateral sclerosis (ALS) and control subjects was injected subcutaneously into the levator auris muscle of mice. A week or a month after the last injection, endplate potentials were recorded. No changes in quantal content of transmitter release were observed. In control and ALS IgG-treated muscles, neurotransmitter release remained sensitive to P/Q-type and insensitive to N-type voltage-sensitive calcium channel (VSCC) blockers as in untreated muscles. In contrast, IgG from 5 of 8 different ALS patients induced a significant reduction in quantal content of the evoked response after incubation with nitrendipine, indicating that a novel sensitivity to this calcium channel blocker appears in these motor nerve terminals. These results indicate that ALS IgG induces plastic changes at nerve terminals. The expression of transmitter release coupled to L-type VSCC indicate that ALS IgGs are capable of inducing plastic changes at the nerve terminals that may participate in the process leading to neuronal death.