Summary A non-coding hexanucleotide repeat expansion in the C9ORF72 gene is the most common mutation associated with familial amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Patients harboring this expansion develop several unique histopathological hallmarks, including intranuclear foci composed of either sense or antisense RNA transcripts from the expanded repeats and dipeptide repeat proteins generated by non-canonical translation of the expanded RNA transcripts. To further investigate the pathological role of C9ORF72 in these diseases, we generated a line of mice carrying a bacterial artificial chromosome containing exons 1 to 6 of the human C9ORF72 gene with approximately 500 repeats of the GGGGCC motif. The mice showed no overt behavioral phenotype but recapitulated distinctive histopathological features that are the hallmark of C9ORF72 ALS/FTD, including sense and antisense intranuclear RNA foci and poly(glycine-proline) dipeptides repeat proteins. Finally, using a synthetic microRNA that targets human C9ORF72 in cultures of primary cortical neurons from the C9BAC mice, we have attenuated expression of the C9BAC transgene and the poly(GP) dipeptides. The C9ORF72 BAC transgenic mice will be a valuable tool in the study of ALS/FTD pathobiology and therapy.

. Mutant SOD1-expressing astrocytes release toxic factors that trigger motoneuron death by inducing hyperexcitability.

No abstract

GGGGCC (G 4 C 2 ) hexanucleotide repeat expansion (HRE) in the first intron of the C9ORF72 (C9) gene is the most common genetic cause of ALS and FTD, two devastating adult-onset neurodegenerative disorders 1,2 . Proposed disease mechanisms include a partial loss of the C9ORF72 protein function (C9ORF72 haploinsufficiency) and acquired toxicity of the repeat expansion 3 . Transcription of the C9ORF72 gene generates three transcript variants: V1, V2 and V3 (Fig. 1a). V1 is translated to produce a short protein isoform (222 amino acids), whereas V2 and V3 generate the most predominant C9ORF72 protein (481 amino acids), which functions in vesicular trafficking 4 . Located adjacent to the promoter region of the most abundant V2 transcript variant, the G 4 C 2 repeat expansion impairs its transcription, leading to C9ORF72 protein haploinsufficiency 5,6 , impaired function of myeloid cells 7,8 and diminished neuronal viability 9 . Both sense and antisense transcripts encompassing the HRE in V1 and V3 generate RNA foci and undergo translation into atypical, aggregation-prone dipeptide repeat (DPR) proteins in all open reading frames 10,11 . These unusual DPRs are toxic in several experimental model systems [12][13][14][15] . Despite important advances in elucidating the molecular pathology of the expanded hexanucleotide repeats, there are no meaningful therapies for C9ORF72-related ALS or FTD.ASOs can drive therapeutic effects by mechanisms that include splice-modulation or, if the ASO contains DNA, activation of endogenous RNase H 16 to degrade the target RNA. The broad bioavailability of ASOs in the central nervous system (CNS), including both neurons and glial cells 17 , has prompted development of ASOs as therapy for dominantly transmitted genetic disorders of the CNS (for example, ALS caused by mutations in the SOD1 gene).Here we report development of ASOs targeting C9ORF72 to treat ALS and FTD. Using different C9-related model systems, including patient-derived samples and two C9BAC transgenic mouse models 18,19 , we generated ASOs that specifically reduce levels of the transcripts harboring the HRE as well as their DPR products, with minimal effects on the most abundant V2 isoform, which does not contain the HRE. We show that modification of a subset of the phosphodiester internucleoside linkages significantly improves ASO tolerability without impairing potency. We demonstrate that, in a single patient harboring mutant C9ORF72 with the G 4 C 2 repeat expressions, repeated intrathecal dosing of the optimal ASO was well tolerated and led to significant and durable reduction in levels of cerebrospinal fluid (CSF) poly(GP). Results ASO suppresses C9ORF72 in fibroblasts and mouse neurons.Because haploinsufficiency of C9ORF72 is thought to be adverse, we developed ASOs that target only the 5′ end of transcripts V1 and V3 that bear the G 4 C 2 repeat expansion, sparing transcript V2. As it is not fully clear whether the repeat-containing intron is retained or spliced out, we focused our effort on ASO sequences targeting ...

Abstract:Axon degeneration occurs in all neurodegenerative diseases, but the molecular pathways regulating axon destruction during neurodegeneration are poorly understood. Sterile Alpha and TIR Motif Containing 1 (Sarm1) is an essential component of the prodegenerative pathway driving axon degeneration after axotomy and represents an appealing target for therapeutic intervention in neurological conditions involving axon loss. Amyotrophic lateral sclerosis (ALS) is characterized by rapid, progressive motor neuron degeneration and muscle atrophy, causing paralysis and death. Patient tissue and animal models of ALS show destruction of upper and lower motor neuron cell bodies and loss of their associated axons. Here, we investigate whether loss of Sarm1 can mitigate motor neuron degeneration in the SOD1G93A mouse model of ALS. We found no change in survival, behavioral, electrophysiogical or histopathological outcomes in SOD1G93A mice null for Sarm1. Blocking Sarm1-mediated axon destruction alone is therefore not sufficient to suppress SOD1G93A-induced neurodegeneration. Our data suggest the molecular pathways driving axon loss in ALS may be Sarm1-independent or involve genetic pathways that act in a redundant fashion with Sarm1.

No abstract

Funding: This trial was funded and sponsored by the University of Chicago. The institution had no role in the design, execution, or analysis of this trial. There was no industry involvement in COVIDOSE.

Background The elderly inflammatory bowel disease (IBD) population has historically been under-represented in clinical trials, and data on the efficacy of biologic medications in elderly IBD patients are generally lacking. Our study aims to evaluate the efficacy of vedolizumab (VDZ) among elderly IBD patients and compare it with younger IBD patients in a nationwide population-based cohort of IBD patients. Methods We conducted a retrospective cohort study of patients within the US national Veterans Affairs Healthcare System (VAHS). Patients were stratified into 2 groups based on age at the time of starting VDZ (60 years of age and older or younger than 60 years of age) with outcomes compared between the 2 groups. The primary outcome was steroid-free remission during the 6- to 12-month period after starting VDZ therapy among those patients who were on steroids when VDZ was started. Results There were 568 patients treated with VDZ, of whom 56.7% had Crohn’s disease and 43.3% had ulcerative colitis. Among them, 316 patients were on steroids when VDZ was started. The percentage of patients who were on VDZ and off steroids during the 6- to 12-month period after VDZ initiation was 46.8% and 40.1% for the younger and elderly groups, respectively (P = 0.2374). Rates of hospitalization for an IBD-related reason within 1 year of VDZ start among the whole cohort were nearly identical in the younger and elderly groups (11.2% vs 11.3%, P = 0.9737). Rates of surgery for an IBD-related reason within 1 year of VDZ start were also similar between the young and elderly (3.9% vs 3.9%, P = 0.9851). Conclusions In a nationwide real-world retrospective cohort study of elderly IBD patients, we found that the efficacy of VDZ was similar among younger and older IBD patients and comparable with the published data in clinical trials.