263 research outputs found
Glatiramer Acetate has no impact on disease progression in ALS at 40 mg/day: a double blind, randomized, multicenter, placebo controlled trial
No full textOur objective was to assess the efficacy and safety of 40 mg/day glatiramer acetate (GA) in patients with ALS. We conducted a double-blind, randomized, placebo-controlled, multicentre trial. Three hundred and sixty-six patients with definite, probable or probable laboratory supported ALS and a slow vital capacity ≥ 70% were randomly assigned to treatment with placebo or 40 mg GA daily. The primary intention-to-treat analysis was the comparison between the two treated groups of the rates of deterioration on the ALSFRSR scale. The secondary outcome measure was time to death, tracheostomy or permanent assisted ventilation. Safety and tolerability of GA were evaluated. After 52 weeks of follow-up, the slope of the ALSFRSR score was comparable in the both groups (placebo,-1.00±0.06/month; GA,-1.05±0.06/month; p=0.48). The secondary endpoint was non-significant with 159 patients (87.4%) alive in the placebo group and 162 patients (88.1%) in the GA group (log rank, p=0.75). The most common events were the injection site reactions (76.1% in the GA group, 14.8% in the placebo group), comparable to the known profile of 20 mg GA. In conclusion, GA at a dose of 40 mg/day did not show any beneficial effect in ALS patients, and safety and tolerability of GA were good in this population
A Representative Survey of M.S. Patients on Attitudes toward the Benefits and Risks of Drug Therapy
No full textBackground: Although M.S. patients face significant trade-offs between risks and benefits of drug therapy, little is known of their attitudes toward these risks and benefits. Methods: A representative telephone survey of 200 patients with relapsing remitting M.S. Results: Respondents suffered substantial disability, most of them requiring a wheel chair or support for walking any significant distance, and over half suffering relapses in the past year. All were on drug therapy; half had switched drugs; 1/3 had switched at least twice.Most patients had seen their neurologist at least 4 times in the previous two years and said they and their physician were equally involved in drug decisions. About 55% said they would definitely or probably use a drug that significantly reduces frequency of relapse or progression in disability even if the drug involves a 1-in-1,000 chance of a fatal side-effect.Willingness to tolerate risk bore little relationship with disability levels. A substantial majority agreed that the FDA should tightly control drugs with safety concerns, but a larger majority agreed that once the FDA has provided a warning, patients should be free to decide with their physician whether to use such drugs. Virtually all said they were willing to visit their neurologist more often in order to use risky drugs. Conclusions: M.S. patients are accustomed to playing a large role in their own drug therapy but do so in close collaboration with their physicians.After the FDA has reviewed drug safety and provided reasonable warnings, many M.S. patients wish to be free to choose to incur a 1-in-1,000 (or even greater) risk of a fatal side-effect in return for significantly more effective drugs, and are willing to work with the physicians in doing so.
Onderzoek naar modificatoren van C9ORF72-geïnduceerde pathologie in amyotrofe lateraal sclerose (ALS) in zebravismodellen
No full textAmyotrophic lateral sclerosis (ALS) is an adult onset neurodegenerative disease characterized by progressive degeneration of upper and lower motor neurons. Clinically, patients present with painless subacute focal muscle weakness. The disease is rapidly progressive, generally leading to death in three to five years after symptom onset, and is unfortunately still incurable.
While in most patients the cause of the disease is unknown, genetic mutations explain ±15% of ALS patients. A non-coding GGGGCC repeat expansion in the C9ORF72 gene is the most frequent genetic cause of ALS. The pathological underpinnings of this mutation are still unclear and might encompass three possible mechanisms. First, decreased transcription of the C9ORF72 gene might lead to loss-of-function of the C9orf72 protein, which has a presumed function in autophagy and membrane trafficking. Second, repeat RNA might bind to several RNA binding proteins (RBPs) hence disturbing their function. This is coined 'RNA toxicity'. Third, the repeat sequence itself might undergo unconventional translation into toxic dipeptide repeats (DPRs), called 'DPR toxicity'. As it is clear that C9orf72 loss-of-function is not the main pathogenic driver, a gain-of-function mechanism seems to be evident. However, at this stage it is still unclear whether this gain-of-function is driven by 'RNA toxicity' or 'DPR toxicity', or even a combination of both. Whereas a definite answer can only be generated in patient material (e.g. post mortem tissue), extensive in vivo disease models have been generated to disentangle this Gordian knot. Whereas several in vivo models have demonstrated the toxic potential of DPRs, in vivo models supporting RNA toxicity are currently lacking.
Therefore, by generating a new zebrafish model we aimed to assess whether repeat RNA can be toxic independent of DPRs, which would be indicative of RNA toxicity as a potential mechanism. Second, we aimed to identify modifiers of this RNA toxicity in order to unravel the mechanism of RNA toxicity.
We generated a transient zebrafish model by injecting repeat RNA into fertilized oocytes. At 30 hours post fertilization, microscopic analysis an axonopathy of spinal motor neurons upon injection of both sense and antisense repeat RNA. Remarkably, no DPRs were detected using both dot blot and immunoassay approaches. As such, this indicates that the presence of repeat RNA in the absence of DPRs is sufficient to cause neuronal toxicity and hence implicates RNA toxicity in the mechanism of C9orf72 ALS. Nevertheless, expression of individual DPRs through codon-optimized constructs revealed GR and PR to induce an axonopathy as well, hence confirming their toxic potential suggested in other in vivo models.
RNA toxicity is believed to be mediated by the repeat RNA compromising the function of several RBPs. Therefore we overexpressed ten RBPs, known to bind repeat RNA, in our zebrafish model. Interestingly five of them (Purα, hnRNPK, hnRNPA3, ALYREF and SRSF1) alleviated the RNA toxicity, indicating that their dysfunction might contribute to RNA toxicity pathogenesis.
Next we focused on Purα to assess how and if this protein is compromised in C9ORF72 ALS. We found the alleviating effect of Purα to be mediated by an induction of p62, mainly via its PUR2 domain, implicating an unexpected involvement of autophagy in RNA toxicity. In line herewith, Purα was found to reverse the increased LC3 levels in C9ORF72 patient derived fibroblasts. Moreover, Purα protein levels were decreased in C9ORF72 fibroblasts as well as in the RNA toxicity zebrafish model, suggesting it to indeed be compromised in C9ORF72 ALS.
Altogether we generated the first in vivo model demonstrating the toxic potential of C9ORF72 repeat RNA independent of DPR generation, thereby supporting RNA toxicity as a potential pathogenic mechanism of C9ORF72 ALS. Additionally, we identified several repeat RNA binding proteins to mitigate the RNA toxicity upon overexpression, suggesting their dysfunction to contribute to RNA toxicity pathogenesis. The dysfunction of one of these proteins, Purα, suggests RNA toxicity to induce disturbed autophagy.
Future research regarding RNA toxicity will need to be twofold. On the one hand, the true involvement of RNA toxicity in C9ORF72 ALS pathogenesis needs to be proven in humans. On the other hand, the mechanism of RNA toxicity needs to be unraveled further by assessing all RNA binding proteins and their downstream targets.status: Publishe
De functionele betekenis van de Notch signaalcascade voor Amyotrofische Laterale Sclerose: een complexe balans tussen goed en slecht.
No full textAmyotrophic lateral sclerosis (ALS) is a devastating late-onset neurodegenerative disease that mainly affects motor neurons. In this disease, motor neuron degeneration is accompanied and aggravated by oligodendroglial pathology and the presence of reactive astrocytes and microglia.
In this PhD thesis, the role of the Notch signaling pathway in ALS was investigated, as this pathway is implicated in several processes that might contribute to the disease, including axonal retraction, microgliosis, astrocytosis, oligodendrocyte precursor cell proliferation and differentiation, and even cell death.
We observed abnormal activation of the Notch signaling pathway in the affected lumbar spinal cord of both SOD1G93A mice, a well-established mouse model of ALS, and patients with sporadic ALS (sALS). This increased Notch signaling activation was particularly evident in reactive astrocytes. In addition, we found that one of the main Notch ligands, namely Jagged-1, was ectopically expressed in reactive astrocytes in the spinal cord from ALS mice and patients, but it was not detected in resting astrocytes.
From Cre-lox mediated modulation experiments in the SOD1G93A mice using ligand-based inactivation approaches, we learned that astrocytic expression of the ligand Jagged-1 is beneficial, since removal further exacerbates Notch pathway activation and accelerates disease progression without affecting disease onset. Ubiquitous deletion of Jagged-1 is beneficial, at least for female SOD1G93A mice, since it delays disease onset and consequently extends survival in female SOD1G93A mice, but not in male SOD1G93A mice. From receptor-based deletion approaches, we learned that ubiquitous deletion of RBPjk, the co-factor crucial for canonical Notch signaling activation through all four Notch receptors, induces early lethality due to gastrointestinal toxicity, and ubiquitous deletion of only the Notch-1 receptor has no effect on the course of disease in the SOD1G93A mouse model, suggesting the importance of other Notch receptors.
Together, these data suggest that aberrant Notch signaling activation is involved in the pathogenesis of ALS, both in sALS patients and in the SOD1G93A mouse model, but plays a rather complex role that potentially consists of both harmful and protective functions. Given the pleiotropic functions of Notch signaling, interference with this pathway as a therapeutic approach must be considered with caution, to circumvent toxic side-effects and effects of disturbing the complex balance between the harmful trans-activation and the protective cis-inhibition.status: Publishe
De rol van EphA4 in herstel na beroerte
No full textStroke is a loss of brain function due to an interruption of cerebral blood flow caused by occlusion (ischemic stroke) or hemorrhage1. It is the leading cause of adult disability and it causes one in 10 deaths worldwide2. The only effective treatments are intravenous recombinant tissue plasminogen activator (rt-PA) and mechanical thrombectomy, which have narrow time windows that limit their use to only a small percentage of patients with ischemic stroke3-5. Therefore, new therapeutic strategies remain necessary.
During stroke, ischemia initiates various molecular events. Due to the lack of blood flow, neurons do not get sufficient amounts of oxygen and metabolic substrates resulting in decreased energy production, excitotoxicity, accumulation of ions, mitochondrial injury and eventually neuronal apoptotic and necrotic cell death causing impaired sensory and motor functioning1,6. Although stroke damage can be devastating, many patients survive the initial event and undergo some spontaneous recovery, a process that can be enhanced by rehabilitation therapy1. Recovery involves different mechanisms including neuronal repair, neurogenesis, alterations in existing neuronal pathways, and the formation of new neuronal connections7. However, these restorative responses are limited due to the upregulation of various inhibitory molecules including myelin associated proteins, components of the glial scar and increased expression of developmental axonal guidance cues like components of the ephrin system8,9.
The ephrin family consists of Eph receptors and ephrin ligands that act as growth inhibitory proteins10,11. One receptor, EphA4, is of specific interest since we have found increased EphA4 protein levels in the ipsilateral and contralateral hemisphere after stroke. This increase starts already at 24 hours and lasts to at least 28 days post-stroke. More specifically, EphA4 expression is upregulated in old sprouting neurons following experimental stroke12,13. In mice with reduced levels of EphA4 or in whom EphA4 downstream signalling pathways have been pharmacologically blocked, functional recovery after experimental stroke is improved14. Furthermore, EphA4 knock out primary cortical neurons show increased neurite outgrowth compared to control cells, suggesting a role of EphA4 in formation of new neuronal projections, a mechanism that enhances stroke recovery14. Additionally, blocking ephrin-A5, a ligand for EphA4, has shown positive effects on neural plasticity and functional outcome after stroke15.
Taken together, these findings suggest an important role of EphA4 in stroke recovery. Moreover, the availability of an EphA4 blocking peptide makes this receptor interesting for therapeutic manipulations. However, the underlying mechanisms as well as the best therapeutic window to target EphA4, in combination with rehabilitation training, remain unknown; therefore further research using different stroke models to validate our initial findings and to determine molecular mechanisms is of great interest.status: Publishe
Report from the Italian Ministerial Committee regarding the diagnosis, care and assistance of patients with ALS
No full text
Value of systematic genetic screening of patients with amyotrophic lateral sclerosis
No full textThe clinical utility of routine genetic sequencing in amyotrophic lateral sclerosis is uncertain. Our
aim was to determine whether routine targeted sequencing of 44 ALS-relevant genes would have a
significant impact on clinical care and disease subclassification. We performed targeted
sequencing of a 44 gene panel in a prospective case series of 100 consecutive ALS patients
recruited sequentially from the Sheffield Motor Neuron Disorders Clinic, United Kingdom. All
participants were diagnosed with ALS by a specialist Consultant Neurologist. 7/100 patients had
familial ALS, but the majority were apparently sporadic cases.
21% of ALS patients carried a confirmed pathogenic or likely-pathogenic mutation, of whom 93%
had no family history of ALS. 15% met the inclusion criteria for a current ALS genetic-therapy trial.
5/21 patients with a pathogenic mutation had an additional variant of uncertain significance (VUS).
An additional 21% of ALS patients carried a VUS in an ALS-associated gene. Overall, 13% of
patients carried more than one genetic variant (pathogenic or VUS). ALS patients carrying two
variants developed disease at a significantly earlier age compared to patients with a single variant
(median age of onset = 56 versus 60 years, p=0.0074).
In conclusion, routine screening for ALS-associated pathogenic mutations in a specialised ALS
referral clinic will impact clinical care in 21% of cases. An additional 21% of patients have variants
in the ALS gene panel currently of unconfirmed significance after removing non-specific or
predicted benign variants. Overall, variants within known ALS-linked genes are of potential clinical
importance in 42% of patients
Identificatie van ziekte-modificerende genen in FUS-geïnduceerd ALS
No full textAmyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are neurodegenerative diseases characterized by the progressive loss of specific groups of neurons. Due to clinical, genetic and pathologic overlap, both diseases are considered as the extremes of one disease spectrum and in a number of ALS and FTD patients, FUS aggregates are present. Even in families with a monogenetic disease cause, a striking variability is observed in disease presentation. This suggests the presence of important modifying genes. The identification of disease-modifying genes could contribute to defining clear therapeutic targets and to understanding the pathways involved in motor neuron death. In this project, we performed genetic screens in an ALS-FUS Drosophila model. In this model, mutant and WT human FUS overexpression in the motor neurons results in a pharate adult eclosion defect. We identified 75 candidate genes, able to modify this phenotype. It became apparent that many proteins in this list were present in intracellular stress granules. Three of them, SAM68 and GSK3β, two Ser/Thr protein kinases and PP2A, a Ser/Thr phosphatase, were further validated. For these validation experiments, we established a novel in vivo screening platform in which new modifying genes of FUS toxicity could be validated. Expression of human FUS induced the selective apoptosis of crustacean cardioactive peptide (CCAP) neurons from the ventral nerve cord of fruit flies. No defects in the development of these neurons were observed, nor were the regulatory CCAP neurons from the brain affected. We used the number of CCAP neurons from the ventral nerve cord as an in vivo read-out for FUS toxicity in neurons. The genetic deletion of SAM68, GSK3β and PP2A could rescue the loss of the CCAP neurons. Further validation of PP2A in patient-derived motor neurons confirmed the important role of PP2A in ALS. Pharmacological inhibition of PP2A, using okadaic acid, restored the recruitment of FUS to DNA damage sites and rescued axonal transport defects. In addition, ALS patients with deleterious mutations in the PP2A genes lived significantly longer in comparison to ALS patients without these deletions. Via a targeted screen, we also discovered a potent modifying role of proteins involved in nucleocytoplasmic transport. Downregulation of Nucleoporin 154 and Exportin1 (XPO1) prevented FUS-induced neurotoxicity. Moreover, we show that XPO1 interacted with FUS. Silencing XPO1 significantly reduced the propensity of FUS to form inclusions upon stress. Taken together, our findings point to an important role of protein kinases and phosphatases and nucleocytoplasmic transport proteins in FUS-induced ALS/FTD.status: Publishe
- …
