Mapping the glial transcriptome in Huntington's disease using snRNAseq: selective disruption of glial signatures across brain regions.

Huntington's disease (HD) is an autosomal dominant neurodegenerative disease with a fatal outcome. There is accumulating evidence of a prominent role of glia in the pathology of HD, and we investigated this by conducting single nuclear RNA sequencing (snRNAseq) of human post mortem brain in four differentially affected regions; caudate nucleus, frontal cortex, hippocampus and cerebellum. Across 127,205 nuclei from donors with HD and age/sex matched controls, we found heterogeneity of glia which is altered in HD.

Calcium-Enhanced Medium-Based Delivery of Splice Modulating Antisense Oligonucleotides in 2D and 3D hiPSC-Derived Neuronal Models.

Antisense technology demonstrates significant potential for addressing inherited brain diseases, with over a dozen products already available and numerous others in the development pipeline. The versatility of differentiating induced pluripotent stem cells (iPSCs) into nearly all neural cell types proves invaluable for comprehending the mechanisms behind neurological diseases, replicating cellular phenotypes, and advancing the testing and development of new therapies, including antisense oligonucleotide therapeutics. While delivering antisense oligonucleotides (ASOs) to human iPSC-based neuronal models has posed challenges, this study explores various delivery methods, including lipid-based transfection, gymnotic uptake, Ca-enhanced medium (CEM)-based delivery, and electroporation, in 2D and 3D hiPSC-derived neuronal models.

Joining forces to develop individualized antisense oligonucleotides for patients with brain or eye diseases: the example of the Dutch Center for RNA Therapeutics.

Antisense oligonucleotides (ASOs) offer versatile tools to modify the processing and expression levels of gene transcripts. As such, they have a high therapeutic potential for rare genetic diseases, where applicability of each ASO ranges from thousands of patients worldwide to single individuals based on the prevalence of the causative pathogenic variant. It was shown that development of individualized ASOs was feasible within an academic setting, starting with Milasen for the treatment of a patient with CLN7 Batten's disease in the USA.

A Guide to Chemical Considerations for the Pre-Clinical Development of Oligonucleotides.

Oligonucleotide therapeutics, a pioneering category of modern medicinal drugs, are at the forefront of utilizing innate mechanisms to modulate gene expression. With 18 oligonucleotide-based FDA-approved medicines currently available for treating various clinical conditions, this field showcases an innovative potential yet to be fully explored. Factors such as purity, formulation, and endotoxin levels profoundly influence the efficacy and safety of these therapeutics.

Generation of human induced pluripotent stem cell lines (LUMCi051-A,B and LUMCi052-A,B,C) of two patients with Spinocerebellar ataxia type 7.

Spinocerebellar Ataxia Type 7 (SCA7) is an autosomal dominantly inherited disorder, primarily characterized by cerebellar ataxia and visual loss. SCA7 is caused by a CAG repeat expansion in exon 3 of the ATXN7 gene. We generated human induced pluripotent stem cells (hiPSCs) from peripheral blood-derived erythroblasts from two SCA7 patients (LUMCi051-A,B and LUMCi052-A,B,C) using integration-free episomal vectors.

Inflammation-induced TRPV4 channels exacerbate blood-brain barrier dysfunction in multiple sclerosis.

Background: Blood-brain barrier (BBB) dysfunction and immune cell migration into the central nervous system (CNS) are pathogenic drivers of multiple sclerosis (MS). Ways to reinstate BBB function and subsequently limit neuroinflammation present promising strategies to restrict disease progression. However, to date, the molecular players directing BBB impairment in MS remain poorly understood.

Biodistribution of Radioactively Labeled Splice Modulating Antisense Oligonucleotides After Intracerebroventricular and Intrathecal Injection in Mice.

Antisense oligonucleotides (AONs) are promising therapeutic candidates, especially for neurological diseases. Intracerebroventricular (ICV) injection is the predominant route of administration in mouse studies, while in clinical trials, intrathecal (IT) administration is mostly used. There is little knowledge on the differences in distribution of these injection methods within the same species over time.

Glucocorticoid receptor antagonist CORT113176 attenuates motor and neuropathological symptoms of Huntington's disease in R6/2 mice.

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) protein resulting in cellular malfunction, aberrant huntingtin aggregation and eventually neuronal cell death. Patients with HD show impaired motor functions and cognitive decline.

Possibilities and limitations of antisense oligonucleotide therapies for the treatment of monogenic disorders.

Antisense oligonucleotides (ASOs) are incredibly versatile molecules that can be designed to specifically target and modify RNA transcripts to slow down or halt rare genetic disease progression. They offer the potential to target groups of patients or can be tailored for individual cases. Nonetheless, not all genetic variants and disorders are amenable to ASO-based treatments, and hence, it is important to consider several factors before embarking on the drug development journey.

Antisense oligonucleotide-mediated disruption of HTT caspase-6 cleavage site ameliorates the phenotype of YAC128 Huntington disease mice.

In Huntington disease, cellular toxicity is particularly caused by toxic protein fragments generated from the mutant huntingtin (HTT) protein. By modifying the HTT protein, we aim to reduce proteolytic cleavage and ameliorate the consequences of mutant HTT without lowering total HTT levels. To that end, we use an antisense oligonucleotide (AON) that targets HTT pre-mRNA and induces partial skipping of exon 12, which contains the critical caspase-6 cleavage site.

GLUT-1 changes in paediatric Huntington disease brain cortex and fibroblasts: an observational case-control study.

Background: Paediatric Huntington disease with highly expanded mutations (HE-PHD; >80 CAG repeats) presents atypically, compared to adult-onset Huntington disease (AOHD), with neurodevelopmental delay, epilepsy, abnormal brain glucose metabolism, early striatal damage, and reduced lifespan. Since genetic GLUT-1 deficiency syndrome shows a symptom spectrum similar to HE-PHD, we investigated the potential role of the two main glucose transporters, GLUT-1 and GLUT-3, in HE-PHD.

Methods: We compared GLUT-1 and GLUT-3 protein expression in HE-PHD, juvenile-onset (JOHD), and AOHD brains (n = 2; n = 3; n = 6) and periphery (n = 3; n = 2; n = 2) versus healthy adult controls (n = 6; n = 6).

Machine learning in Huntington's disease: exploring the Enroll-HD dataset for prognosis and driving capability prediction.

Background: In biomedicine, machine learning (ML) has proven beneficial for the prognosis and diagnosis of different diseases, including cancer and neurodegenerative disorders. For rare diseases, however, the requirement for large datasets often prevents this approach. Huntington's disease (HD) is a rare neurodegenerative disorder caused by a CAG repeat expansion in the coding region of the huntingtin gene.

Early molecular layer interneuron hyperactivity triggers Purkinje neuron degeneration in SCA1.

Toxic proteinaceous deposits and alterations in excitability and activity levels characterize vulnerable neuronal populations in neurodegenerative diseases. Using in vivo two-photon imaging in behaving spinocerebellar ataxia type 1 (Sca1) mice, wherein Purkinje neurons (PNs) degenerate, we identify an inhibitory circuit element (molecular layer interneurons [MLINs]) that becomes prematurely hyperexcitable, compromising sensorimotor signals in the cerebellum at early stages. Mutant MLINs express abnormally elevated parvalbumin, harbor high excitatory-to-inhibitory synaptic density, and display more numerous synaptic connections on PNs, indicating an excitation/inhibition imbalance.

Spinocerebellar Ataxia Type 1 Characteristics in Patient-Derived Fibroblast and iPSC-Derived Neuronal Cultures.

Background: Spinocerebellar ataxia type 1 (SCA1) is a neurodegenerative disease caused by a polyglutamine expansion in the ataxin-1 protein resulting in neuropathology including mutant ataxin-1 protein aggregation, aberrant neurodevelopment, and mitochondrial dysfunction.

Objectives: Identify SCA1-relevant phenotypes in patient-specific fibroblasts and SCA1 induced pluripotent stem cells (iPSCs) neuronal cultures.

Methods: SCA1 iPSCs were generated and differentiated into neuronal cultures.

Therapeutic Strategies for Spinocerebellar Ataxia Type 1.

Spinocerebellar ataxia type 1 (SCA1) is an autosomal dominant neurodegenerative disorder that affects one or two individuals per 100,000. The disease is caused by an extended CAG repeat in exon 8 of the gene and is characterized mostly by a profound loss of cerebellar Purkinje cells, leading to disturbances in coordination, balance, and gait. At present, no curative treatment is available for SCA1.

The potential value of disease-modifying therapy in patients with spinocerebellar ataxia type 1: an early health economic modeling study.

Objective: There currently is no disease-modifying therapy for spinocerebellar ataxia type 1 (SCA1). Genetic interventions, such as RNA-based therapies, are being developed but those currently available are very expensive. Early evaluation of costs and benefits is, therefore, crucial.

Amyloid beta accumulations and enhanced neuronal differentiation in cerebral organoids of Dutch-type cerebral amyloid angiopathy patients.

Introduction: ADutch-type cerebral amyloid angiopathy (D-CAA) is a hereditary brain disorder caused by a point mutation in the amyloid precursor protein (APP) gene. The mutation is located within the amyloid beta (Aβ) domain of APP and leads to Aβ peptide accumulation in and around the cerebral vasculature. There lack of disease models to study the cellular and molecular pathological mechanisms of D-CAA together with the absence of a disease phenotype in vitro in overexpression cell models, as well as the limited availability of D-CAA animal models indicates the need for a D-CAA patient-derived model.

Development of tailored splice-switching oligonucleotides for progressive brain disorders in Europe: development, regulation, and implementation considerations.

Splice-modulating antisense oligonucleotides (ASOs) offer treatment options for rare neurological diseases, including those with very rare mutations, where patient-specific, individualized ASOs have to be developed. Inspired by the development of milasen, the 1 Mutation 1 Medicine (1M1M) and Dutch Center for RNA Therapeutics (DCRT) aim to develop patient-specific ASOs and treat eligible patients within Europe and the Netherlands, respectively. Treatment will be provided under a named patient setting.

Consensus Guidelines for the Design and Preclinical Efficacy Testing N-of-1 Exon Skipping Antisense Oligonucleotides.

Antisense oligonucleotides (ASOs) can modulate pre-mRNA splicing. This offers therapeutic opportunities for numerous genetic diseases, often in a mutation-specific and sometimes even individual-specific manner. Developing therapeutic ASOs for as few as even a single patient has been shown feasible with the development of Milasen for an individual with Batten disease.

Potential disease-modifying therapies for Huntington's disease: lessons learned and future opportunities.

Huntington's disease is the most frequent autosomal dominant neurodegenerative disorder; however, no disease-modifying interventions are available for patients with this disease. The molecular pathogenesis of Huntington's disease is complex, with toxicity that arises from full-length expanded huntingtin and N-terminal fragments of huntingtin, which are both prone to misfolding due to proteolysis; aberrant intron-1 splicing of the HTT gene; and somatic expansion of the CAG repeat in the HTT gene. Potential interventions for Huntington's disease include therapies targeting huntingtin DNA and RNA, clearance of huntingtin protein, DNA repair pathways, and other treatment strategies targeting inflammation and cell replacement.

Iron accumulation induces oxidative stress, while depressing inflammatory polarization in human iPSC-derived microglia.

Iron accumulation in microglia has been observed in Alzheimer's disease and other neurodegenerative disorders and is thought to contribute to disease progression through various mechanisms, including neuroinflammation. To study this interaction, we treated human induced pluripotent stem cell-derived microglia (iPSC-MG) with iron, in combination with inflammatory stimuli such as interferon gamma (IFN-γ) and amyloid β. Both IFN-γ and iron treatment increased labile iron levels, but only iron treatment led to a consistent increase of ferritin levels, reflecting long-term iron storage.

Co-expression patterns of microglia markers Iba1, TMEM119 and P2RY12 in Alzheimer's disease.

Microglia have been identified as key players in Alzheimer's disease pathogenesis, and other neurodegenerative diseases. Iba1, and more specifically TMEM119 and P2RY12 are gaining ground as presumedly more specific microglia markers, but comprehensive characterization of the expression of these three markers individually as well as combined is currently missing. Here we used a multispectral immunofluorescence dataset, in which over seventy thousand microglia from both aged controls and Alzheimer patients have been analysed for expression of Iba1, TMEM119 and P2RY12 on a single-cell level.