Title Promoter Affiliations Abstract "Study of SPTAN1 pathomechanisms: the spectrin complex as a central hub in rare neurological and neuromuscular diseases." "Jonathan Baets" "Translational Neurosciences (TNW)" "Next Generation Sequencing technologies have accumulated genetic causes for Mendelian diseases, often without full insight into the cellular function of the gene involved. Conversely, patients with rare neurogenetic diseases are often lacking a genetic etiology. SPTAN1 (?-II-spectrin), a major cytoskeletal protein, is exemplary in this with a notably wide phenotypic spectrum but surprisingly little understanding of its molecular and cellular biology. Previously only associated with epilepsy and intellectual disability, we recently published novel mutations in SPTAN1 associated with Hereditary Motor Neuropathy and now also in Ataxia and Hereditary Spastic Paraplegia. ?-II-spectrin is the central component of the spectrin complex and is widely expressed in all cells but how its disturbances cause various neurological diseases is poorly understood. We will establish both cortical and motor neurons from patient-derived induced pluripotent stem-cells of three SPTAN1 mutations that are representative for the main associated diseases. Cytoskeletal abnormalities in these neurons will be studied using super-resolution microscopy, axonal transport assays and electrophysiological studies. Transcriptome-profiling of the neuronal cultures will allow to explore the interaction network of the spectrin complex. Ultimately, we will generate novel functional candidate genes that will be translated back to large genetic datasets of patients with diagnostically unresolved neurogenetic diseases." "TOWARDS TRIAL READINESS IN HEREDITARY NEUROMUSCULAR DISEASES: Developing accurate, feasible and non-invasive outcome measures." "Kristl Claeys" "Laboratory for Muscle Diseases and Neuropathies, Processing Speech and Images (PSI), Laboratory for Molecular Neurobiomarker Research, Laboratory for Cognitive Neurology" "To evaluate the effect of a new treatment in clinical trials, we first need an adequate knowledge of the natural history of the disease in question, and a set of outcome measures to evaluate disease progression. Additionally, these outcome measures should be sensitive, reliable, objective, non-invasive and feasible. This thesis aims to improve trial readiness for three hereditary neuromuscular diseases: LGMDR12, BMD and SMA.In chapter 1, we showed that Dixon PDFF imaging and Biodex® dynamometry of the thighs are sensitive outcome measures that can track disease progression in adults with LGMDR12 over the course of 1 year. We discovered that patients with a moderate baseline thigh muscle PDFF experienced a faster rate of muscle fat replacement on MRI and could therefore be selected for clinical trials to display a potential therapeutic effect with increased sensitivity. Additionally, we demonstrated that the PDFF analysis of an entire stack of Dixon MR images was superior to sampling single slices of thigh muscles, and we suggested that analysis of individual muscles could be better than muscle groups. Because such extensive PDFF analyses are not feasible, we trained a CNN to semi-automate muscle segmentation to mitigate this issue. In chapter 2, we applied 3D muscle segmentations from the iliac crest to the tibial plateau to detail the pattern of fat replacement in 18 thigh muscles in patients with LGMDR12. We discovered an inhomogeneous non-linear distribution of fat replacement in all examined muscles, which underscored the risk of sampling bias, and implied that muscle fat replacement in neuromuscular disorders cannot be assumed to occur homogeneously in thigh muscles. Based on all the results above, we postulated that 3D whole muscle segmentation for analysis of Dixon PDFF should become the benchmark method in quantitative MR imaging studies. Additionally, we showed that muscle PDFF correlated to muscle biopsy fat fraction and other histopathological findings in affected muscles of patients with LGMDR12. This provided further confirmation of the validity of Dixon MR imaging in LGMDR12. In chapter 3, we studied respiratory decline in adults with BMD and concluded that a more vigilant follow-up of respiratory function in non-ambulatory patients is warranted. In chapter 4, we showed that PDFF measurement by 3D analysis of entire thigh muscles could detect disease progression in adults with BMD after only 9 months of follow-up. Given that a matched control group also showed a slight increase in PDFF, we argued that this should be accounted for when interpreting the results of future clinical trials. Out of a wide range of additional outcome measures, we revealed that the ActivLim scale (a PROM), and the MFM-32 or NSAA were sensitive enough to capture disease progression over 9 months. In chapter 5, we evaluated the potential of MR elastography as an outcome measure in adults with BMD. First, we designed the necessary equipment for muscle MRE imaging. Next, we demonstrated that test-retest reliability of muscle MRE was strongly variable in a group of subjects with and without muscle diseases. In contrast, test-retest reliability of PDFF and muscle volume measurements with 3D segmentation models was excellent. Finally, we discovered that thigh muscle stiffness was significantly lower in adults with BMD than in matched healthy controls, but that stiffness did not change over 9 months of follow-up. We concluded that muscle MRE imaging in its current form is not reliable enough to be applied in clinical trials. In chapter 6, we showed that nusinersen is a safe and efficacious treatment for adults with SMA, with improvements in hand grip strength, hand motor function, and skeletal muscle strength as measured by the MRC sum score over 14 months of follow-up. In addition, we detailed the natural history of untreated adults with SMA retrospectively and compared this with the improvements measured under treatment with nusinersen. In chapter 7, we reported further clinical improvements after 22 months of follow-up in nusinersen-treated adults with SMA. Additionally, we analyzed neuroinflammatory and neurodegenerative biomarkers in CSF and serum. Although CHIT1 and pNfH levels in CSF changed significantly over 22 months of nusinersen treatment, this did not correlate to changes in clinical outcome measures. Despite these interesting findings, we could not yet propose a biochemical biomarker of disease progression for follow-up of treatment effect in adults with SMA. In conclusion, we advanced trial readiness for LGMDR12, BMD and SMA by describing the natural history of these diseases and examining outcome measures of disease progression. These results are important for the design and analysis of future clinical trials. Finally, we also demonstrated that nusinersen is a safe and efficacious treatment for adults with SMA." "A preclinical study to treat neuromuscular disease caused by mutations in the small heat check protein HSPB8." "Vincent Timmerman" "Peripheral Neuropathies Group" "Patients with autosomal dominant distal hereditary motor neuropathy (dHMN) develop progressive motor impairments, weakness and wasting of lower limb muscles. We identified mutations in the small heat shock protein HSPB8 as one of the underlying genetic causes for this disease. More recently, distal myopathy was also found to be associated with mutations in HSPB8. So far, no treatment is available to delay or cure patients with mutations in HSPB8. Our research group generated a mouse model mimicking the symptoms observed in affected individuals by introducing a known disease-causing mutation (knock-in: KI). Additionally, we also generated a mouse model in which HSPB8 was deleted (knock-out: KO). Strikingly, the latter does not show any sign of neuronal damage or severe myopathy. We therefore hypothesise that reducing the levels of HSPB8 might help to alleviate the symptoms associated with dHMN. This project aims to identify therapeutic compounds that by reducing HSPB8 levels, can rescue or delay the neurodegeneration observed in the KI model. It could therefore deliver the first small molecule treatment for neuropathies and myopathies caused by mutations in HSPB8. Furthermore, this strategy will also open therapeutic possibilities for other neuromuscular and neurodegenerative diseases where HSPB8 plays a role in the pathology." "Clinical and molecular characterization of a novel congenital disease; the role of PREPL in regulated secretion and neuromuscular transmission" "John Creemers" "Department of Human Genetics" "PREPL (PRolyl EndoPeptidase-Like) is deleted in a recessive metabolic disorder characterized by muscle weakness and growth hormone deficiency. Based on the homology with PREP (PRolyl EndoPeptidase) PREPL was predicted to encode an oligopeptidase. Although activity of the catalytic machinery has been demonstrated, no peptide substrates have been identified so far. Recently, we have achieved a breakthrough in determining the physiological function of PREPL; we have found that administration of an acetylcholine-esterase inhibitor greatly improves weakness in some PREPL-deficient patients, pointing at impaired exocytosis at the neuromuscular junction. Furthermore, PREPL knockdown in a neuroendocrine cell line reduced regulated secretion. Finally, an interaction with the adaptor protein AP-1 was found, which also requires phosphatidylinositol 4-phosphate (PI-4-P) for high-affinity binding. Since PREPL increases membrane dissociation of AP-1, we hypothesize that PREPL hydrolyzes PI-4-P.The aim of this research is to characterize the role of PREPL in regulated secretion and neuromuscular transmission. The three objectives of the project are: To test an alternative for the acetylcholine-esterase inhibitor, which may not only have a broader effect on weakness but might also improve growth.To study the role of PREPL in regulated secretion in cell lines, in hippocampal neurons and in somatotrophs of a mouse model.To determine if PREPL has PI-4-P hydrolase activity. " "Learning-based computational strategies for multimodal image analysis of neurovascular diseases" "Frederik Maes" "Laboratory for Neurobiology (VIB-KU Leuven), Processing Speech and Images (PSI)" "Neurovascular diseases such as ischemic stroke are one of the most prevalent causes of disability worldwide. In ischemic stroke, blood flow to a specific region of the brain is hampered by a thrombosis or embolism occluding a cerebral artery. The main treatment strategies of ischemic stroke consist of restoring perfusion through intravenous injection of a thrombolytic drug and/or endovascular thrombectomy, with time from onset to reperfusion being a determining factor in terms of patient outcome. The severity of the stroke is clinically assessed based on conventional perfusion parameters such as cerebral blood flow and time-to-maximum extracted from a 4D perfusion CT scan acquired prior to treatment. But the outcome thereof is affected by image quality, by computational factors and by the lack of inclusion of treatment specific parameters. The aim of this thesis is to investigate alternative, learning-based strategies that allow for a more comprehensive analysis of the patient imaging data to more reliably predict treatment outcome in stroke and other neurovascular diseases by accounting as well for imaging data of previous cases, non-imaging data of the patient (e.g. EEG) and metadata in the form of clinical parameters." "Genomics of inherited neuromuscular disorders and beyond: towards the development of novel biomarkers and therapies." "Peter De Jonghe" "Department of Biomedical Sciences - other, Neurogenetics Group" "Neuromuscular disorders (NMD) form a large and diverse group of usually genetic diseases affecting spinal cord, peripheral nerve, neuromuscular junction and muscle. Most NMD are 'rare disorders' affecting less than 1 in 2000 individuals but the estimated total of 5000-7000 rare disorders affect 30 million Europeans. Most NMD are chronic, debilitating and often life-threatening resulting in tremendous disease burden for patients and society. The common challenges in NMD are: substantial delays in diagnosis due to lack of reliable diagnostic tools; lack of specialized centres and standards for optimal patient care; lack of fundamental understanding of the mechanisms of disease and the absence of effective therapies. In this project we will focus on inherited disorders of the peripheral nerve and skeletal muscle. First we will conduct large-scale genetic studies to improve patient diagnosis and to increase our understanding of the crucial mechanisms leading to the disease. Secondly we aim to study the striking variability in disease severity of NMD and confront this with the study of patient-derived tissues such as skin and muscle biopsies. This will help in the design of reliable 'disease biomarkers' that can be used to predict severity of disease and can also serve as a tool to follow the response to experimental therapies. Lastly we will use patient derived tissues to help identifying novel targets and strategies for future therapy of NMD." "Neuromuscular disorders: from the omics-age towards novel therapies." "Translational Neurosciences (TNW)" "Neuromuscular disorders (NMD) are diverse, usually inheriteddisorders that are chronically debilitating with tremendous societalimpact. We will focus on Hereditary Motor Neuropathies (HMN) andInherited/ Idiopathic Muscle Diseases (IMD). The unmet needs are""missing heritability"" and lack of patho-mechanistic understandingand effective therapies. First, we will identify novel genetic causes ofHMN/IMD through advanced genetic studies in large patient cohortswithin international consortia. This allows the identification of rarecauses and unconventional mutation mechanisms. Secondly, basedon our recent identification of α-spectrin mutations in HMN we willstudy the associated spectrum of neuro-spectrinopathies. We willapply advanced machine learning techniques to a custom-builtdatabase featuring known and novel mutations. This will drivemutations modelling in patient derived induced pluripotent stem cellsin order to unravel the roles of the neuronal spectrin-cytoskeleton.Thirdly we will design novel therapies for idiopathic muscle disease,the most important being sporadic inclusion body myositis (sIBM).Using high-resolution proteomics techniques, we found that a keyupstream regulator driving the pathology is KDM5A, a histonedemethylase that induces failure of muscle regeneration in sIBMmuscle. We will use preclinical validation in cellular models to studytherapeutic KDM5A inhibition (pat. pend.) and will seek strategicindustry partners to develop this further." "The role of PREPL in regulated secretion and neuromuscular transmission." "John Creemers" "Laboratory for Biochemical Neuroendocrinology, Department of Human Genetics" "The Hypotonia-Cystinuria syndrome is caused by deletions of the Prolyl Endopeptidase-like (PREPL) and SLC3A1 genes on chromosome 2p21. This recessive metabolic syndrome is characterized by cystinuria, neonatalhypotonia and growth hormone deficiency. Since it is well established that inactivating mutations or deletions in the SLC3A1 gene cause isolated cystinuria, all other symptoms can be attributed to the deletion ofPREPL. How PREPL deficiency causes these clinical manifestations is currently unknown. Based on its homology with PREP (Prolyl EndoPeptidase), PREPL was predicted to encode an oligopeptidase. Although activity of the catalytic machinery has been demonstrated, no peptide substrates have been identified so far. Preliminary results suggest that PREPL is involved in neuromuscular transmission and regulated secretion, whichcorresponds to the observed symptoms in HCS patients. Therefore, the aim of this research is to characterize the function of PREPL in regulatedsecretion in neuroencrine cell lines, as well as at the neuromuscular junction, in hippocampal neurons and somatotrophs of a PREPL KO mouse model." "Cellular and molecular mechanisms of VEGF at the level of the neuromuscular junction: implications for the treatment of ALS." "Peter Carmeliet" "Laboratory of Angiogenesis and Vascular Metabolism (VIB-KU Leuven), Department of Human Genetics" "Neurodegenerative disorders (Alzheimer, Parkinson and Amytrophic lateral sclerosis (ALS)) form a group of diseases in which a selected cell population progressively dies, resulting in functional loss. Patients, suffering from any neurodegenerative disorder, have physical, mental and social disabilities and often die at young age since there is no pro-regenerative effective therapy available. Therefore, for all of these disorders, development of new therapies is absolutely required. However, before efficient therapies can emerge, we will first need to extend todays knowledge of underlying action mechanisms. The aim of this study is to unravel the cellular mechanisms by which the vascular endothelial growth factor (VEGF) acts on peripheral neurons and skeletal muscles, two tissues highly affected in ALS. To achieve this goal, we will use the major transgenic model for ALS (SOD1G93A mice), to determine to what extend muscle derived VEGF signaling can influence ALS disease progression and which mechanisms and cellular targets mediate this effect." "Cardiovascular and muscle-specific ""targeting"" for gene therapy of neuromuscular disorders" "Thierry VandenDriessche" "Cell Biology and Histology" "Gene therapy is the use of DNA as a drug to treat disease by delivering therapeutic DNA into a patient's cells. In this project we will implement cardiovascular and muscle-specific ""targeting"" for gene therapy of neuromuscular disorders."