Huntington's Disease (HD) is a progressive neurodegenerative disease caused by a mutation in the huntingtin gene. The mutation leads to a toxic gain of function of the mutant huntingtin (mHtt)... Show moreHuntington's Disease (HD) is a progressive neurodegenerative disease caused by a mutation in the huntingtin gene. The mutation leads to a toxic gain of function of the mutant huntingtin (mHtt) protein resulting in cellular malfunction, aberrant huntingtin aggregation and eventually neuronal cell death. Patients with HD show impaired motor functions and cognitive decline. Elevated levels of glucocorticoids have been found in HD patients and in HD mouse models, and there is a positive correlation between increased glucocorticoid levels and the progression of HD. Therefore, antagonism of the glucocorticoid receptor (GR) may be an interesting strategy for the treatment of HD. In this study, we evaluated the efficacy of the selective GR antagonist CORT113176 in the commonly used R6/2 mouse model. In male mice, CORT113176 treatment significantly delayed the loss of grip strength, the development of hindlimb clasping, gait abnormalities, and the occurrence of epileptic seizures. CORT113176 treatment delayed loss of DARPP-32 immunoreactivity in the dorsolateral striatum. It also restored HD -related parameters including astrocyte markers in both the dorsolateral striatum and the hippocampus, and microglia markers in the hippocampus. This suggests that CORT113176 has both cell -type and brain regionspecific effects. CORT113176 delayed the formation of mHtt aggregates in the striatum and the hippocampus. In female mice, we did not observe major effects of CORT113176 treatment on HD -related symptoms, with the exception of the anti -epileptic effects. We conclude that CORT113176 effectively delays several key symptoms related to the HD phenotype in male R6/2 mice and believe that GR antagonism may be a possible treatment option. Show less
Amyotrophic Lateral Sclerosis (ALS) is a fatal neurodegenerative disorder characterised by a progressive loss of motor function. Despite the strives into growing knowledge on ALS, fundamental... Show moreAmyotrophic Lateral Sclerosis (ALS) is a fatal neurodegenerative disorder characterised by a progressive loss of motor function. Despite the strives into growing knowledge on ALS, fundamental obstacles remain into understanding disease causation and nominating drug targets for a cure. With this work, we widen our understanding of ALS through the analysis of single-nuclei RNA-sequencing dataset of patients’ and control motorcortices. We show intrinsically higher expression of ALS-related genes in Extratelencephalic Neurons accompanied by selective vulnerability of subsets of cortical motor neurons. These changes are found with alterations in oligodendrocytes and microglia that widen our knowledge of cell-to-cell interactions in ALS. We use hiPSC-derived in vitro systems to model the molecular changes identified. Secondly, we offer a wide view on models of human brain cells in a dish to encompass protocols useful for modelling complex cell-to-cell interactions in ALS. Moreover, we describe a human in vitro system for the study of motor neuron that is highly reproducible, scalable and high-throughput. This new method allows the assessment of multiple cell lines in the same dish and could provide insights into heterogeneity in human populations and mechanisms disrupted in disease. We then use these models to further dissect molecular mechanisms disrupted in ALS. We undertake a discussion onto the future of the field and hopefully the opening to a more holistic approach to the understanding of ALS, where multidisciplinary techniques and the use of different models might expand our perspectives on the disease. Show less
Degenerative diseases of the nervous system, such as Alzheimer's, Parkinson's and ALS, are severe, progressive and ultimately fatal. Most existing drugs for these neurodegenerative diseases only... Show moreDegenerative diseases of the nervous system, such as Alzheimer's, Parkinson's and ALS, are severe, progressive and ultimately fatal. Most existing drugs for these neurodegenerative diseases only temporarily relieve symptoms, increase mobility or relieve pain, but do not slow disease progression.This dissertation describes a method to efficiently carry out the development of new drugs that could inhibit disease progression in neurodegenerative diseases. Namely, by using pharmacodynamic biomarkers. These are signaling substances to measure the magnitude of a drug response.These biomarkers can be used in early clinical-pharmacological studies in healthy volunteers or small groups of patients to select the best drug candidates and their expected therapeutic doses as early as possible in the development stage. This helps to make informed choices to advance a potential new drug into large and expensive phase 2 and 3 (registration) studies, or conversely to discontinue development of a non-potential drug as early as possible. This biomarker method was applied in this dissertation to investigate 2 new drugs that could potentially slow disease progression in Alzheimer's and ALS (a RIPK1 inhibitor) or Parkinson's disease (a LRRK2 inhibitor). The research results from multiple early clinical-pharmacological studies in healthy volunteers and patients described in this thesis form the basis for larger phase 2 and 3 follow-up studies that have now been initiated with ALS patients and Parkinson's disease patients. Both with the goal of confirming whether these agents can indeed slow disease progression, which would represent a major breakthrough in the treatment of these conditions. Show less
Prins, S.; Borghans, L.; Kam, M.L. de; Groeneveld, G.J.; Gerven, J. van 2023
Background The prevalence of neurodegenerative diseases increases significantly with increasing age. Neurodegeneration is the progressive loss of function of neurons that eventually leads to cell... Show moreBackground The prevalence of neurodegenerative diseases increases significantly with increasing age. Neurodegeneration is the progressive loss of function of neurons that eventually leads to cell death, which in turn leads to cognitive disfunction. Cognitive performance can therefore also be considered age dependent. The current study investigated if the NeuroCart can detect age related decline on drug-sensitive CNS-tests in healthy volunteers (HV), and whether there are interactions between the rates of decline and sex. This study also investigated if the NeuroCart was able to differentiate disease profiles of neurodegenerative diseases, compared to age-matched HV and if there is age related decline in patient groups. Methods This retrospective study encompassed 93 studies, performed at CHDR between 2005 and 2020 that included NeuroCart measurements, which resulted in data from 2729 subjects. Five NeuroCart tests were included in this analysis: smooth and saccadic eye movements, body sway, adaptive tracking, VVLT and N-back. Data from 84 healthy male and female volunteer studies, aged 16-90, were included. Nine studies were performed in patients with Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD) or vascular dementia (VaD). The data were analyzed with regression analyses on age by group, sex, sex by age, group by sex and group by sex by age. Least square means (LSMs) and 95% confidence intervals (CIs) were calculated for each group at the average age of the group, and at the average age of each of the other groups, and per sex. Results Mean age and standard deviation (SD) for all groups was: HV 36.2 years (19.3), AD 68.3 years (8), PD 62.7 years (8.5), HD 51.4 years (9.8) and VaD 66.9 years (8.1). Performance on all NeuroCart tests decreased significantly each year in HV. Saccadic peak velocity (SPV) was increased in AD compared to age-matched HV (+26.28 degrees/s, p =0.007), while SPV was decreased for PD and HD compared to age-matched HV (PD: -15.87 degrees/s, p=0.038, HD: -22.52 degrees/s, p=0.018). In HD patients SPV decreased faster with age compared to HV. On saccadic peak velocity the slopes between HD vs HV were significantly different, indicating a faster decline in performance on this task for HD patients compared to HV per age year. Smooth pursuit showed an overall significant difference between subject groups (p=0.037. Significantly worse performance was found for AD (-12.87%, p=<0.001), PD (-4.45%, p=<0.001) and VaD (-5.69%, p=0.005) compared to age-matched HV. Body sway significantly increased with age (p=0.021). Postural stability was decreased for both PD and HD compared to age-matched HV (PD: +38.8%, p=<0.001, HD: 154.9%, p=<0.001). The adaptive tracking was significantly decreased with age (p=<0.001). Adaptive tracking performance by AD (-7.54%, p=<0.001), PD (-8.09%, p=<0.001), HD (-5.19%, p=<0.001) and VaD (-5.80%, p=<0.001) was decreased compared to age-matched HV. Adaptive tracking in PD patients vs HV and in PD vs HD patients was significantly different, indicating a faster decline on this task per age year for PD patients compared to HV and HD. The VVLT delayed word recall showed an overall significant effect of subject group (p=0.006. Correct delayed word recall was decreased for AD (-5.83 words, p=<0.001), HD (-3.40 words, p=<0.001) and VaD (-5.51 words, p=<0.001) compared to age-matched HV. Conclusion This study showed that the NeuroCart can detect age-related decreases in performance in HV, which were not affected by sex. The NeuroCart was able to detect significant differences in performance between AD, PD, HD, VaD and age-matched HV. Disease durations were unknown, therefore this cross-sectional study was not able to show age-related decline after disease onset. This article shows the importance of investigating age-related decline on digitalized neurocognitive test batteries. Performance declines with age, which emphasizes the need to correct for age when including HV in clinical trials. Patients with different neurogenerative diseases have distinct performance patterns on the NeuroCart , which this should be considered when performing NeuroCart tasks in patients with AD, PD, HD and VaD. Show less
How to define the preclinical Alzheimer's Disease state in otherwise healthy elderly. How to best select otherwise healthy elderly for clinical trials participation with a disease modifiying... Show moreHow to define the preclinical Alzheimer's Disease state in otherwise healthy elderly. How to best select otherwise healthy elderly for clinical trials participation with a disease modifiying compound. Difference between healthy elderly and subjects in the preclinical AD stage on biomarker level. Difference in cognitive performance in healthy subjects compared to neurodegenerative disease profiles. Show less
The ventral tegmental area dopamine (VTA-DA) mesolimbic circuit processes emotional, motivational, and social reward associations together with their more demanding cognitive aspects that involve... Show moreThe ventral tegmental area dopamine (VTA-DA) mesolimbic circuit processes emotional, motivational, and social reward associations together with their more demanding cognitive aspects that involve the mesocortical circuitry. Coping with stress increases VTA-DA excitability, but when the stressor becomes chronic the VTA-DA circuit is less active, which may lead to degeneration and local microglial activation. This switch between activation and inhibition of VTA-DA neurons is modulated by e.g. corticotropin-releasing hormone (CRH), opioids, brain-derived neurotrophic factor (BDNF), and the adrenal glucocorticoids. These actions are coordinated with energy-demanding stress-coping styles to promote behavioral adaptation. The VTA circuits show sexual dimorphism that is programmed by sex hormones during perinatal life in a manner that can be affected by glucocorticoid exposure. We conclude that insight in the role of stress in VTA-DA plasticity and connectivity, during reward processing and stress-coping, will be helpful to better understand the mechanism of resilience to breakdown of adaptation. Show less
Huntington’s disease (HD) is a progressive autosomal dominant neurodegenerative disorder with a broad spectrum of clinical features. The disease is caused by a mutation in the Huntingtin gene (HTT... Show moreHuntington’s disease (HD) is a progressive autosomal dominant neurodegenerative disorder with a broad spectrum of clinical features. The disease is caused by a mutation in the Huntingtin gene (HTT) on the short arm of chromosome 4. In September 2015, the first-in-human study looking into the safety of an intrathecally administered antisense oligonucleotide therapy to reduce mutant HTT (mHTT) protein was launched in HD patients, where the drug proved to be safe and the intended mHTT lowering was demonstrated. The aim of this thesis is to find biomarkers corresponding with disease state and measuring progression in different stages of HD, which in turn can be used as suitable objective surrogate clinical trial endpoints. We put special emphasis on longitudinal study designs, as these provide the most useful clinical progression and parameter change associations. Although previous neuroimaging studies have shown potential markers, findings remain inconsistent or lacking association with disease state. As such, further exploration of neuroimaging techniques is of great relevance. Using different approaches to evaluate the potential usefulness of specific markers, we demonstrate biomarkers that may assist in the objective assessment of a potential disease-modifying intervention. Show less
The subject of this Thesis is the role of the immune system in age-related eye diseases, such as glaucoma. Glaucoma is a disease that afflicts nearly 70 million people worldwide. Little is known... Show moreThe subject of this Thesis is the role of the immune system in age-related eye diseases, such as glaucoma. Glaucoma is a disease that afflicts nearly 70 million people worldwide. Little is known about the origins of the disease, which damages the retina and optic nerve and can lead to blindness. One of the biggest risk factors for glaucoma is elevated eye pressure. Our study found that glaucoma may in fact be an autoimmune disorder. We found that the body’s own T cells are responsible for the progressive retinal degeneration seen in glaucoma. Furthermore these T cells appear to be primed to attack retinal neurons as the result of previous interactions with bacteria that normally live in our body. This opens a new approach to prevent and treat glaucoma. Currently most treatments focus on lowering eye pressure. However, in many patients, the disease worsens even after intraocular pressure returns to normal. We showed that when we blocked these autoreactive T cells in the eye, not only does it diminish the loss of retinal ganglion cells and axons, but it also preserves retinal function. Show less
Huntington’s disease (HD) is a progressive autosomal dominant inherited neurodegenerative disorder.The primary aim of this thesis is to examine alterations in the cerebral cortex in HD gene... Show moreHuntington’s disease (HD) is a progressive autosomal dominant inherited neurodegenerative disorder.The primary aim of this thesis is to examine alterations in the cerebral cortex in HD gene carriers. Different image modalities and approaches will be used to extent the knowledge on both structural and functional cortical brain changes in early disease. Although striatal atrophy is more extensively present in HD, changes in the cerebral cortex can also be detected in the pre-symptomatic stage. Different methodological approaches used in our studies all showed a consistent pattern of cortical atrophy making volumetric MRI a reliable and effective tool to assess early in-vivo cortical brain changes, even in a rare neurodegenerative disorder such as HD. The influence of cortical changes on other clinical signs that occur in HD should not be overlooked. Our results demonstrate that volume loss and thinning of the cerebral cortex, especially the posterior brain regions, is detectable in early stages and contributes to the presence of specific motor signs and cognitive impairments. We believe that intervention trials could benefit from using cortical volumes as outcome measures, instead of using striatal volumes alone. Show less
The aim of this thesis is to examine employment and driving ability in gene carriers with Huntington’s disease (HD). HD is an autosomal-dominant inherited neurodegenerative disorder and manifests... Show moreThe aim of this thesis is to examine employment and driving ability in gene carriers with Huntington’s disease (HD). HD is an autosomal-dominant inherited neurodegenerative disorder and manifests during mid adulthood. The disease is clinically characterized by motor disturbances, cognitive decline and behavioral changes. Since there is currently no cure for HD, the focus of treatment is on improving quality of life and providing the necessary support to patients and families. Maintaining independence through employment and driving, for as long and as safely as possible, has a substantial influence on a patient’s general functioning. Our results consistently showed that the cognitive and behavioral changes of HD are more debilitating in daily life than the characteristic motor signs, and are associated with employment and driving a car. Healthcare professionals should be educated about HD to allow them to provide appropriate information to patients and families when discussing possible changes in working and driving as a result of HD. Individual evaluation of driving ability is warranted and the recommendation to stop driving should not solely be based on disease stage or a genetic confirmation. Multidisciplinary screening, using a HD-specific test battery, is recommended and should be embedded in the clinic. Show less
Ilie, A.; Gao, A.Y.L.; Boucher, A.; Park, J.; Berghuis, A.M.; Hoffer, M.J.V.; ... ; Orlowski, J. 2019
Huntington disease (HD) is the best know of the polyglutamine disorders which are caused by the excessive expansion of a CAG repeat in a transcribed gene. It is estimated that there are 1300 HD... Show moreHuntington disease (HD) is the best know of the polyglutamine disorders which are caused by the excessive expansion of a CAG repeat in a transcribed gene. It is estimated that there are 1300 HD patients in the Netherlands and even more people that are currently at risk. Translation of the CAG repeat results in proteins with an expanded polyglutamine repeat. Expansion of this repeat above a threshold of 36 results in an aggregation prone protein leading to disease onset around mid-life. In all polyglutamine diseases an inverse correlation is found between repeat expansion and age of disease onset. Neuronal intranuclear inclusions (NII) which contain at least part of the expanded protein are identified as hallmarks of the polyglutamine diseases. Inclusions have been suggested to function as protective storage sites implying that soluble misfolded proteins are the primary cause of toxicity. The aggregation prone properties of these proteins are causing the pathological gain of function due to interference with normal cellular function. The ubiquitin proteasome system (UPS) is responsible for the main protein degradation within the cell. The UPS contributes to cellular homeostasis by regulating the expression of essential proteins and degradation of excessive proteins. In addition, the UPS is involved in cellular protein quality control and responsible for the degradation of aberrant proteins that accumulate in neurodegeneration. Also expanded polyglutamine proteins can be degraded by the UPS in order to protect the cell from this aggregation prone protein. However, the expanded repeat is also difficult to degrade causing impairment of the proteasome and consequential accumulation. The general introduction in Chapter 1 gives an overview of several of the important aspects leading to neurodegeneration in HD and specifically the contribution of the UPS. Chapter 2 describes the discovery of molecular misreading which occurs on GAGAG motifs in different genes. The frameshift mutant of ubiquitin B (UBB+1) is formed by a dinucleotide deletion (_GU) in the mRNA. The mutant ubiquitin protein that is formed can no longer ubiquitinate substrate proteins but is a target for ubiquitination and subsequent proteasomal degradation. UBB+1 accumulates in several neurodegenerative diseases and is an in vivo marker for proteasomal inhibition. In Chapter 3, we investigated the accumulation of UBB+1 in HD and Spinocerebellar ataxia-3 (SCA3) and potential contribution to neurodegeneration. UBB+1 was found to accumulate in the cytoplasm and NII in the affected brain regions of HD and SCA3 demonstrating in vivo proteasome inhibition in these disorders. In a cellular model of HD we observed that UBB+1 results in inhibition of the proteasome which causes increased aggregate formation. In addition, a synergistic increase in polyglutamine induced cell death was found upon expression of UBB+1. These findings implicate UBB+1 as an aggravating factor in polyglutamine induced neurodegeneration and stresses the importance of the UPS for degradation of aberrant polyglutamine and UBB+1 proteins. UBB+1 transgenic mice show a mild inhibition of the proteasome. In Chapter 4 we tested the influence of this UPS inhibition by UBB+1 on Htt aggregation in vivo. Expression of expanded polyglutamine protein in the striatum of the UBB+1 transgenic mice showed a strong increase in NII formation compared to wildtype littermates. These results demonstrate in vivo that minor differences in UPS capacity can have major detrimental effects on the neuropathology of HD. The ubiquitin conjugating enzyme E2-25K has been shown to interact directly with Htt independent of polyglutamine repeat length. In Chapter 5, we investigated the localization of E2-25K in HD as well as the contribution to neurodegeneration. E2-25K co-localizes with a subset of NII in HD brain as well as with aggregates in apoptotic cells in vitro. Dominant negative E2-25K __ lacking the catalytic tail domain __ as well as an antisense construct decreased aggregate formation of expanded Htt. Additionally, mutant and antisense E2-25K reduced polyglutamine-induced cell death. These findings show that ubiquitination of E2-25K-targets contributes to aggregate formation as well as neuronal cell death in HD. Finally, in Chapter 6 the different findings of this thesis are discussed as well as further research and perspectives. In conclusion, the findings of this thesis illustrate the importance of the UPS for the cellular clearance of toxic proteins involved in neurodegeneration. The precise mechanism of specific neuronal dysfunction in HD is still unclear but is triggered by the gain of function of the polyglutamine repeat. Impairment of the UPS results in the further accumulation of aberrant proteins and subsequent neuronal dysfunction. Since HD is caused by protein expression from a mutant allele, more efficient degradation could protect the neurons from harmful polyglutamine proteins. Show less
