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Frontotemporal dementia and amyotrophic lateral sclerosis (FTD-ALS) are associated with both a repeat expansion in the C9orf72 gene and mutations in the TANK-binding kinase 1 ( TBK1 ) gene. We found that TBK1 is phosphorylated in response to C9orf72 poly(Gly-Ala) [poly(GA)] aggregation and sequestered into inclusions, which leads to a loss of TBK1 activity and contributes to neurodegeneration. When we reduced TBK1 activity using a TBK1-R228H (Arg 228 →His) mutation in mice, poly(GA)-induced phenotypes were exacerbated. These phenotypes included an increase in TAR DNA binding protein 43 (TDP-43) pathology and the accumulation of defective endosomes in poly(GA)-positive neurons. Inhibiting the endosomal pathway induced TDP-43 aggregation, which highlights the importance of this pathway and TBK1 activity in pathogenesis. This interplay between C9orf72 , TBK1 , and TDP-43 connects three different facets of FTD-ALS into one coherent pathway.

Abnormal expansions of GGGGCC repeat sequence in the noncoding region of the C9orf72 gene is the most common cause of familial amyotrophic lateral sclerosis and frontotemporal dementia (C9-ALS/FTD). The expanded repeat sequence is translated into dipeptide repeat proteins (DPRs) by noncanonical repeat-associated non-AUG (RAN) translation. Since DPRs play central roles in the pathogenesis of C9-ALS/FTD, we here investigate the regulatory mechanisms of RAN translation, focusing on the effects of RNA-binding proteins (RBPs) targeting GGGGCC repeat RNAs. Using C9-ALS/FTD model flies, we demonstrated that the ALS/FTD-linked RBP FUS suppresses RAN translation and neurodegeneration in an RNA-binding activity-dependent manner. Moreover, we found that FUS directly binds to and modulates the G-quadruplex structure of GGGGCC repeat RNA as an RNA chaperone, resulting in the suppression of RAN translation in vitro. These results reveal a previously unrecognized regulatory mechanism of RAN translation by G-quadruplex-targeting RBPs, providing therapeutic insights for C9-ALS/FTD and other repeat expansion diseases.

Repeat expansions in theC9orf72gene are the most common genetic cause of amyotrophic lateral sclerosis and familial frontotemporal dementia (ALS/FTD). To identify molecular defects that take place in the dorsolateral frontal cortex of patients withC9orf72ALS/FTD, we compared healthy controls withC9orf72ALS/FTD donor samples staged based on the levels of cortical phosphorylated TAR DNA binding protein (pTDP-43), a neuropathological hallmark of disease progression. We identified distinct molecular changes in different cell types that take place during disease progression. These alterations include downregulation of nuclear and mitochondrial ribosomal protein genes in early disease stages that become upregulated as the disease progresses. High ratios of premature oligodendrocytes expressing low levels of genes encoding major myelin protein components are characteristic of late disease stages and may represent a unique signature ofC9orf72ALS/FTD. Microglia with increased reactivity and astrocyte specific transcriptome changes in genes involved in glucose/glycogen metabolism are also associated with disease progression. Late stages ofC9orf72ALS/FTD correlate with sequential changes in the regulatory landscape of several genes in glial cells, namelyMBP/MAG/MOGin oligodendrocytes,CD83/IRF8in microglia, andGLUT1/GYS2/AGLin astrocytes. Only layer 2-3 cortical projection neurons with high expression ofCUX2/LAMP5are significantly reduced inC9orf72ALS/FTD patients with respect to controls. Our findings reveal previously unknown progressive functional changes in cortical cells ofC9orf72ALS/FTD patients that shed light on the mechanisms underlying the pathology of this disease.

Hexanucleotide G

A hexanucleotide repeat expansion GGGGCC in the non-coding region of C9orf72 is the most common cause of inherited amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Toxic dipeptide repeats (DPRs) are synthesized from GGGGCC via repeat-associated non-AUG (RAN) translation. Here, we develop C. elegans models that express, either ubiquitously or exclusively in neurons, 75 GGGGCC repeats flanked by intronic C9orf72 sequence. The worms generate DPRs (poly-glycine-alanine [poly-GA], poly-glycine-proline [poly-GP]) and poly-glycine-arginine [poly-GR]), display neurodegeneration, and exhibit locomotor and lifespan defects. Mutation of a non-canonical translation-initiating codon (CUG) upstream of the repeats selectively reduces poly-GA steady-state levels and ameliorates disease, suggesting poly-GA is pathogenic. Importantly, loss-of-function mutations in the eukaryotic translation initiation factor 2D (eif-2D/eIF2D) reduce poly-GA and poly-GP levels, and increase lifespan in both C. elegans models. Our in vitro studies in mammalian cells yield similar results. Here, we show a conserved role for eif-2D/eIF2D in DPR expression.

A hexanucleotide repeat expansion in intron 1 of the

Abnormal expansions of GGGGCC repeat sequence in the noncoding region of theC9orf72gene is the most common cause of familial amyotrophic lateral sclerosis and frontotemporal dementia (C9-ALS/FTD). The expanded repeat sequence is translated into dipeptide repeat proteins (DPRs) by noncanonical repeat-associated non-AUG (RAN) translation. Since DPRs play central roles in the pathogenesis of C9-ALS/FTD, we here investigate the regulatory mechanisms of RAN translation, focusing on the effects of RNA-binding proteins (RBPs) targeting GGGGCC repeat RNAs. Using C9-ALS/FTD model flies, we demonstrated that the ALS/FTD-linked RBP FUS suppresses RAN translation and neurodegeneration in an RNA-binding activity-dependent manner. Moreover, we found that FUS directly binds to and modulates the G-quadruplex structure of GGGGCC repeat RNA as an RNA chaperone, resulting in the suppression of RAN translationin vitro. These results reveal a previously unrecognized regulatory mechanism of RAN translation by G-quadruplex-targeting RBPs, providing therapeutic insights for C9-ALS/FTD and other repeat expansion diseases.

A hexanucleotide repeat expansion in intron 1 of the C9orf72 gene is the most common genetic cause of amyotrophic lateral sclerosis and frontotemporal dementia, or c9ALS/FTD. The RNA transcribed from the expansion, r(G 4 C 2 ) exp , causes various pathologies, including intron retention, aberrant translation that produces toxic dipeptide repeat proteins (DPRs), and sequestration of RNA-binding proteins (RBPs) in RNA foci. Here, we describe a small molecule that potently and selectively interacts with r(G 4 C 2 ) exp and mitigates disease pathologies in spinal neurons differentiated from c9ALS patient-derived induced pluripotent stem cells (iPSCs) and in two c9ALS/FTD mouse models. These studies reveal a mode of action whereby a small molecule diminishes intron retention caused by the r(G 4 C 2 ) exp and allows the liberated intron to be eliminated by the nuclear RNA exosome, a multi-subunit degradation complex. Our findings highlight the complexity of mechanisms available to RNA-binding small molecules to alleviate disease pathologies and establishes a pipeline for the design of brain penetrant small molecules targeting RNA with novel modes of action in vivo.

Arginine-rich dipeptide repeat proteins (R-DPRs), abnormal translational products of a GGGGCC hexanucleotide repeat expansion in

To examine the length of a hexanucleotide expansion in C9orf72, which represents the most frequent genetic cause of frontotemporal lobar degeneration and motor neuron disease, we employed a targeted amplification-free long-read sequencing technology: No-Amp sequencing. In our cross-sectional study, we assessed cerebellar tissue from 28 well-characterized C9orf72 expansion carriers. We obtained 3507 on-target circular consensus sequencing reads, of which 814 bridged the C9orf72 repeat expansion (23%). Importantly, we observed a significant correlation between expansion sizes obtained using No-Amp sequencing and Southern blotting (P = 5.0 × 10−4). Interestingly, we also detected a significant survival advantage for individuals with smaller expansions (P = 0.004). Additionally, we uncovered that smaller expansions were significantly associated with higher levels of C9orf72 transcripts containing intron 1b (P = 0.003), poly(GP) proteins (P = 1.3 × 10− 5), and poly(GA) proteins (P = 0.005). Thorough examination of the composition of the expansion revealed that its GC content was extremely high (median: 100%) and that it was mainly composed of GGGGCC repeats (median: 96%), suggesting that expanded C9orf72 repeats are quite pure. Taken together, our findings demonstrate that No-Amp sequencing is a powerful tool that enables the discovery of relevant clinicopathological associations, highlighting the important role played by the cerebellar size of the expanded repeat in C9orf72-linked diseases., DeJesus-Hernandez et al. employ an innovative long-read sequencing method to examine the length of the expanded C9orf72 repeat that represents the most common genetic cause of frontotemporal dementia and amyotrophic lateral sclerosis. Smaller expansion size confers a survival benefit for patients.

Background Mesenchymal stromal cells (MSCs) have been studied with increasing intensity as clinicians and researchers strive to understand the ability of MSCs to modulate disease progression and promote tissue regeneration. As MSCs are used for diverse applications, it is important to appreciate how specific physiological environments may stimulate changes that alter the phenotype of the cells. One need for neuroregenerative applications is to characterize the spectrum of MSC responses to the cerebrospinal fluid (CSF) environment after their injection into the intrathecal space. Mechanistic understanding of cellular biology in response to the CSF environment may predict the ability of MSCs to promote injury repair or provide neuroprotection in neurodegenerative diseases. Methods In this study, we characterized changes in morphology, metabolism, and gene expression occurring in human adipose-derived MSCs cultured in human (hCSF) or artificial CSF (aCSF) as well as examined relevant protein levels in the CSF of subjects treated with MSCs for amyotrophic lateral sclerosis (ALS). Results Our results demonstrated that, under intrathecal-like conditions, MSCs retained their morphology, though they became quiescent. Large-scale transcriptomic analysis of MSCs revealed a distinct gene expression profile for cells cultured in aCSF. The aCSF culture environment induced expression of genes related to angiogenesis and immunomodulation. In addition, MSCs in aCSF expressed genes encoding nutritional growth factors to expression levels at or above those of control cells. Furthermore, we observed a dose-dependent increase in growth factors and immunomodulatory cytokines in CSF from subjects with ALS treated intrathecally with autologous MSCs. Conclusions Overall, our results suggest that MSCs injected into the intrathecal space in ongoing clinical trials remain viable and may provide a therapeutic benefit to patients.

No treatment for frontotemporal dementia (FTD), the second most common type of early-onset dementia, is available, but therapeutics are being investigated to target the 2 main proteins associated with FTD pathological subtypes: TDP-43 (FTLD-TDP) and tau (FTLD-tau). Testing potential therapies in clinical trials is hampered by our inability to distinguish between patients with FTLD-TDP and FTLD-tau. Therefore, we evaluated truncated stathmin-2 (STMN2) as a proxy of TDP-43 pathology, given the reports that TDP-43 dysfunction causes truncated STMN2 accumulation. Truncated STMN2 accumulated in human induced pluripotent stem cell-derived neurons depleted of TDP-43, but not in those with pathogenic TARDBP mutations in the absence of TDP-43 aggregation or loss of nuclear protein. In RNA-Seq analyses of human brain samples from the NYGC ALS cohort, truncated STMN2 RNA was confined to tissues and disease subtypes marked by TDP-43 inclusions. Last, we validated that truncated STMN2 RNA was elevated in the frontal cortex of a cohort of patients with FTLD-TDP but not in controls or patients with progressive supranuclear palsy, a type of FTLD-tau. Further, in patients with FTLD-TDP, we observed significant associations of truncated STMN2 RNA with phosphorylated TDP-43 levels and an earlier age of disease onset. Overall, our data uncovered truncated STMN2 as a marker for TDP-43 dysfunction in FTD.

Mitochondrial dysfunction is an early, imminent event in neurodegenerative disorders including Parkinson disease (PD) and Alzheimer disease (AD). The enzymatic pair PINK1 and PRKN/Parkin recognize and transiently label damaged mitochondria with ubiquitin (Ub) phosphorylated at Ser65 (p-S65-Ub) as a signal for degradation via the autophagy-lysosome system (mitophagy). Despite its discovery in cell culture several years ago, robust and quantitative detection of altered mitophagy in vivo has remained challenging. Here we developed a sandwich ELISA targeting p-S65-Ub with the goal to assess mitophagy levels in mouse brain and in human clinical and pathological samples. We characterized five total Ub and four p-S65-Ub antibodies by several techniques and found significant differences in their ability to recognize phosphorylated Ub. The most sensitive antibody pair detected recombinant p-S65-Ub chains in the femtomolar to low picomolar range depending on the poly-Ub chain linkage. Importantly, this ELISA was able to assess very low baseline mitophagy levels in unstressed human cells and in brains from wild-type and prkn knockout mice as well as elevated p-S65-Ub levels in autopsied frontal cortex from AD patients vs. control cases. Moreover, the assay allowed detection of p-S65-Ub in blood plasma and was able to discriminate between PINK1 mutation carriers and controls. In summary, we developed a robust and sensitive tool to measure mitophagy levels in cells, tissue, and body fluids. Our data strongly support the idea that the stress-activated PINK1-PRKN mitophagy pathway is constitutively active in mice and humans under unstimulated, physiological and elevated in diseased, pathological conditions. Abbreviations: Ab: antibody; AD: Alzheimer disease; AP: alkaline phosphatase; CV: coefficient of variation; ECL: electrochemiluminescence; KO: knockout; LoB: Limit of Blank; LoD: Limit of Detection; LoQ: Limit of Quantification; MSD: meso scale discovery; PD: Parkinson disease; p-S65-PRKN: phosphorylated PRKN at serine 65; p-S65-Ub: phosphorylated ubiquitin at serine 65; Std.Dev.: standard deviation; Ub: ubiquitin; WT: wild type

Hexanucleotide expansions in C9orf72, which encodes a predicted guanine exchange factor, are the most frequent genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Although repeat expansion has been established to generate toxic products, mRNAs encoding the C9ORF72 protein are also reduced in affected individuals. In this study, we tested how C9ORF72 protein levels affected repeat-mediated toxicity. In somatic transgenic mice expressing 66 GGGGCC repeats, inactivation of one or both endogenous C9orf72 alleles provoked or accelerated, respectively, early death. In mice expressing a C9orf72 transgene with 450 repeats that did not encode the C9ORF72 protein, inactivation of one or both endogenous C9orf72 alleles exacerbated cognitive deficits, hippocampal neuron loss, glial activation and accumulation of dipeptide-repeat proteins from translation of repeat-containing RNAs. Reduced C9ORF72 was shown to suppress repeat-mediated elevation in autophagy. These efforts support a disease mechanism in ALS/FTD resulting from reduced C9ORF72, which can lead to autophagy deficits, synergizing with repeat-dependent gain of toxicity.

The most common cause of amyotrophic lateral sclerosis and frontotemporal dementia (c9ALS/FTD) is an expanded G(4)C(2) RNA repeat [r(G(4)C(2))(exp)] in chromosome 9 open reading frame 72 (C9orf72), which elicits pathology through several mechanisms. Here, we developed and characterized a small molecule for targeted degradation of r(G(4)C(2))(exp). The compound was able to selectively bind r(G(4)C(2))(exp)’s structure and to assemble an endogenous nuclease onto the target, provoking removal of the transcript by native RNA quality control mechanisms. In c9ALS patient–derived spinal neurons, the compound selectively degraded the mutant C9orf72 allele with limited off-targets and reduced quantities of toxic dipeptide repeat proteins (DPRs) translated from r(G(4)C(2))(exp). In vivo work in a rodent model showed that abundance of both the mutant allele harboring the repeat expansion and DPRs were selectively reduced by this compound. These results demonstrate that targeted small-molecule degradation of r(G(4)C(2))(exp) is a strategy for mitigating c9ALS/FTD-associated pathologies and studying disease-associated pathways in preclinical models.

The hexanucleotide repeat expansion GGGGCC [r(G(4)C(2))(exp)] within intron 1 of C9orf72 causes genetically defined amyotrophic lateral sclerosis and frontotemporal dementia, collectively named c9ALS/FTD. , the repeat expansion causes neurodegeneration via deleterious phenotypes stemming from r(G(4)C(2))(exp) RNA gain- and loss-of-function mechanisms. The r(G(4)C(2))(exp) RNA folds into both a hairpin structure with repeating 1 × 1 nucleotide GG internal loops and a G-quadruplex structure. Here, we report the identification of a small molecule (CB253) that selectively binds the hairpin form of r(G(4)C(2))(exp). Interestingly, the small molecule binds to a previously unobserved conformation in which the RNA forms 2 × 2 nucleotide GG internal loops, as revealed by a series of binding and structural studies. NMR and molecular dynamics simulations suggest that the r(G(4)C(2))(exp) hairpin interconverts between 1 × 1 and 2 × 2 internal loops through the process of strand slippage. We provide experimental evidence that CB253 binding indeed shifts the equilibrium toward the 2 × 2 GG internal loop conformation, inhibiting mechanisms that drive c9ALS/FTD pathobiology, such as repeat-associated non-ATG translation formation of stress granules and defective nucleocytoplasmic transport in various cellular models of c9ALS/FTD.

Hospitalized patients with COVID-19 show increased serum concentrations of neurofilament light chain that correlate with worse clinical outcomes., Brain damage marker in COVID-19 SARS-CoV-2 infection, the cause of coronavirus disease 2019 (COVID-19), causes neurological manifestations in a substantial proportion of patients. Determining the extent of neuronal injury is essential to better understand disease pathophysiology and to evaluate potential therapies. Prudencio et al. analyzed serum from 142 patients hospitalized with COVID-19 and showed that the expression of the neurofilament light protein (NFL), a marker of neuroaxonal injury, was elevated compared to healthy controls. In addition, serum NFL expression correlated with disease severity and tended to be reduced in subjects treated with remdesivir. The results suggest that serum NFL analysis should be incorporated when evaluating therapeutic trials for COVID-19., Brain imaging studies of patients with COVID-19 show evidence of macro- and microhemorrhagic lesions, multifocal white matter hyperintensities, and lesions consistent with posterior reversible leukoencephalopathy. Imaging studies, however, are subject to selection bias, and prospective studies are challenging to scale. Here, we evaluated whether serum neurofilament light chain (NFL), a neuroaxonal injury marker, could predict the extent of neuronal damage in a cohort of 142 hospitalized patients with COVID-19. NFL was elevated in the serum of patients with COVID-19 compared to healthy controls, including those without overt neurological manifestations. Higher NFL serum concentrations were associated with worse clinical outcomes. In 100 hospitalized patients with COVID-19 treated with remdesivir, a trend toward lower NFL serum concentrations was observed. These data suggest that patients with COVID-19 may experience neuroaxonal injury and may be at risk for long-term neurological sequelae. Neuroaxonal injury should be considered as an outcome in acute pharmacotherapeutic trials for COVID-19.

Expanded GGGGCC (G4C2) repeats in C9ORF72 cause amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). How RNAs containing expanded G4C2 repeats are transcribed in human neurons is largely unknown. Here we describe a Drosophila model in which poly(GR) expression in adult neurons causes axonal and locomotor defects and premature death without apparent TDP-43 pathology. In an unbiased genetic screen, partial loss of Lilliputian (Lilli) activity strongly suppresses poly(GR) toxicity by specifically downregulating the transcription of GC-rich sequences in Drosophila. Knockout of AFF2/FMR2 (one of four mammalian homologues of Lilli) with CRISPR-Cas9 decreases the expression of the mutant C9ORF72 allele containing expanded G4C2 repeats and the levels of repeat RNA foci and dipeptide repeat proteins in cortical neurons derived from induced pluripotent stem cells of C9ORF72 patients, resulting in rescue of axonal degeneration and TDP-43 pathology. Thus, AFF2/FMR2 regulates the transcription and toxicity of expanded G4C2 repeats in human C9ORF72-ALS/FTD neurons., Mechanisms of transcription of expanded G4C2 repeats in C9ORF72, associated with ALS/FTD, are not fully understood. Here authors use both Drosophila and C9ORF72 iPSC-derived neurons and identify AFF2/FMR2 as a regulator of poly(GR) toxicity by regulating expression of the expanded G4C2 repeats.

The majority of the clinico-pathological variability observed in patients harboring a repeat expansion in the C9orf72-SMCR8 complex subunit (C9orf72) remains unexplained. This expansion, which represents the most common genetic cause of frontotemporal lobar degeneration (FTLD) and motor neuron disease (MND), results in a loss of C9orf72 expression and the generation of RNA foci and dipeptide repeat (DPR) proteins. The C9orf72 protein itself plays a role in vesicular transport, serving as a guanine nucleotide exchange factor that regulates GTPases. To further elucidate the mechanisms underlying C9orf72-related diseases and to identify potential disease modifiers, we performed an extensive RNA sequencing study. We included individuals for whom frontal cortex tissue was available: FTLD and FTLD/MND patients with (n = 34) or without (n = 44) an expanded C9orf72 repeat as well as control subjects (n = 24). In total, 6706 genes were differentially expressed between these groups (false discovery rate [FDR] C9orf72 (FDR = 1.41E-14), which was roughly two-fold lower in C9orf72 expansion carriers than in (disease) controls. Co-expression analysis revealed groups of correlated genes (modules) that were enriched for processes such as protein folding, RNA splicing, synaptic signaling, metabolism, and Golgi vesicle transport. Within our cohort of C9orf72 expansion carriers, machine learning uncovered interesting candidates associated with clinico-pathological features, including age at onset (vascular endothelial growth factor A [VEGFA]), C9orf72 expansion size (cyclin dependent kinase like 1 [CDKL1]), DPR protein levels (eukaryotic elongation factor 2 kinase [EEF2K]), and survival after onset (small G protein signaling modulator 3 [SGSM3]). Given the fact that we detected a module involved in vesicular transport in addition to a GTPase activator (SGSM3) as a potential modifier, our findings seem to suggest that the presence of a C9orf72 repeat expansion might hamper vesicular transport and that genes affecting this process may modify the phenotype of C9orf72-linked diseases.

OBJECTIVE: We assessed the incidence of deep vein thrombosis (DVT) and pulmonary embolism (PE) in hospitalized patients with coronavirus disease 2019 (COVID-19) compared with that in a matched cohort with similar cardiovascular risk factors and the effects of DVT and PE on the hospital course. METHODS: We performed a retrospective review of prospectively collected data from COVID-19 patients who had been hospitalized from March 11, 2020 to September 4, 2020. The patients were randomly matched in a 1:1 ratio by age, sex, hospital of admission, smoking history, diabetes mellitus, and coronary artery disease with a cohort of patients without COVID-19. The primary endpoint was the incidence of DVT/PE and the odds of developing DVT/PE using a conditional logistic regression model. The secondary endpoint was the hospitalization outcomes for COVID-19 patients with and without DVT/PE, including mortality, intensive care unit (ICU) admission, ICU stay, and length of hospitalization (LOH). Multivariable regression analysis was performed to identify the variables associated with mortality, ICU admission, discharge disposition, ICU duration, and LOH. RESULTS: A total of 13,310 patients had tested positive for COVID-19, 915 of whom (6.9%) had been hospitalized across our multisite health care system. The mean age of the hospitalized patients was 60.8 ± 17.0 years, and 396 (43.3%) were women. Of the 915 patients, 82 (9.0%) had had a diagnosis of DVT/PE confirmed by ultrasound examination of the extremities and/or computed tomography angiography of the chest. The odds of presenting with DVT/PE in the setting of COVID-19 infection was greater than that without COVID-19 infection (0.6% [5 of 915] vs 9.0% [82 of 915]; odds ratio [OR], 18; 95% confidence interval [CI], 8.0-51.2; P < .001). The vascular risk factors were not different between the COVID-19 patients with and without DVT/PE. Mortality (P = .02), the need for ICU stay (P < .001), duration of ICU stay (P < .001), and LOH (P < .001) were greater in the DVT/PE cohort than in the cohort without DVT/PE. On multivariable logistic regression analysis, the hemoglobin (OR, 0.71; 95% CI, 0.46-0.95; P = .04) and D-dimer (OR, 1.0; 95% CI, 0.33-1.56; P = .03) levels were associated with higher mortality. Higher activated partial thromboplastin times (OR, 1.1; 95% CI, 1.00-1.12; P = .03) and higher interleukin-6 (IL-6) levels (OR, 1.0; 95% CI, 1.01-1.07; P = .05) were associated with a greater risk of ICU admission. IL-6 (OR, 1.0; 95% CI, 1.00-1.02; P = .05) was associated with a greater risk of rehabilitation placement after discharge. On multivariable gamma regression analysis, hemoglobin (coefficient, -3.0; 95% CI, 0.03-0.08; P = .005) was associated with a prolonged ICU stay, and the activated partial thromboplastin time (coefficient, 2.0; 95% CI, 0.003-0.006; P = .05), international normalized ratio (coefficient, -3.2; 95% CI, 0.06-0.19; P = .002) and IL-6 (coefficient, 2.4; 95% CI, 0.0011-0.0027; P = .02) were associated with a prolonged LOH. CONCLUSIONS: A significantly greater incidence of DVT/PE occurred in hospitalized COVID-19-positive patients compared with a non-COVID-19 cohort matched for cardiovascular risk factors. Patients affected by DVT/PE were more likely to experience greater mortality, to require ICU admission, and experience prolonged ICU stays and LOH compared with COVID-19-positive patients without DVT/PE. Advancements in DVT/PE prevention are needed for patients hospitalized for COVID-19 infection.

Author(s): Boeve, Bradley F; Boxer, Adam L; Rosen, Howard J; Forsberg, Leah K; Heuer, Hilary W; Brushaber, Danielle; Appleby, Brian; Biernacka, Joanna M; Bordelon, Yvette M; Botha, Hugo; Brannelly, Patrick; Dickerson, Brad C; Dickson, Dennis W; Kimiko, Domoto‐Reilly; Faber, Kelley; Fagan, Anne; Fields, Julie A; Fishman, Ann; Foroud, Tatiana M; Galasko, Doug R; Gavrilova, Ralitza H; Gendron, Tania F; Geschwind, Daniel H; Ghoshal, Nupur; Goldman, Jill; Graff‐Radford, Jonathan; Graff‐Radford, Neill R; Grant, Ian; Grossman, Murray; Hsiung, Ging‐Yuek Robin; Huang, Eric J; Huey, Edward; Irwin, David J; Jones, David T; Kantarci, Kejal; Karydas, Anna M; Kaufer, Daniel; Knopman, David S; Kramer, Joel H; Kremers, Walter K; Kornak, John; Kukull, Walter A; Lagone, Emma; Leger, Gabriel C; Litvan, Irene; Ljubenkov, Peter A; Lucente, Diane E; Mackenzie, Ian R; Manoochehri, Masood; Masdeu, Joseph C; McGinnis, Scott; Mendez, Mario F; Miller, Bruce L; Miyagawa, Toji; Nelson, Kevin M; Onyike, Chiadi U; Pantelyat, Alex; Pascual, Belen; Pearlman, Rodney; Petrucelli, Leonard; Rademakers, Rosa; Ramos, Eliana Marisa; Rankin, Katherine; Rascovsky, Katya; Rexach, Jessica E; Ritter, Aaron; Roberson, Erik D; Rojas, Julio C; Sabbagh, Marwan N; Salmon, David P; Savica, Rodolfo; Seeley, William W; Staffaroni, Adam M; Syrjanen, Jeremy; Tartaglia, Carmela; Tatton, Nadine; Taylor, Joanne; Toga, Arthur W; Weintraub, Sandra; Wheaton, Diana; Wong, Bonnie; Wszolek, Zbigniew

Frontotemporal dementia (FTD) therapy development is hamstrung by a lack of susceptibility, diagnostic, and prognostic biomarkers. Blood neurofilament light (NfL) shows promise as a biomarker, but studies have largely focused only on core FTD syndromes, often grouping patients with different diagnoses. To expedite the clinical translation of NfL, we avail ARTFL LEFFTDS Longitudinal Frontotemporal Lobar Degeneration (ALLFTD) study resources and conduct a comprehensive investigation of plasma NfL across FTD syndromes and in presymptomatic FTD mutation carriers. We find plasma NfL is elevated in all studied syndromes, including mild cases; increases in presymptomatic mutation carriers prior to phenoconversion; and associates with indicators of disease severity. By facilitating the identification of individuals at risk of phenoconversion, and the early diagnosis of FTD, plasma NfL can aid in participant selection for prevention or early treatment trials. Moreover, its prognostic utility would improve patient care, clinical trial efficiency, and treatment outcome estimations.

Genetically defined amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), collectively named c9ALS/FTD, are triggered by hexanucleotide GGGGCC repeat expansions [r(G(4)C(2))(exp)] within the C9orf 72 gene. In these diseases, neuronal loss occurs through an interplay of deleterious phenotypes, including r(G(4)C(2))(exp) RNA gain-of-function mechanisms. Herein, we identified a benzimidazole derivative, CB096, that specifically binds to a repeating 1×1 GG internal loop structure, 5′CGG/3′GGC, that is formed when r(G(4)C(2))(exp) folds. Structure−activity relationship (SAR) studies and molecular dynamics (MD) simulations were used to define the molecular interactions formed between CB096 and r(G(4)C(2))(exp) that results in the rescue of disease-associated pathways. Overall, this study reveals a unique structural feature within r(G(4)C(2))(exp) that can be exploited for the development of lead medicines and chemical probes.

Given the substantial heterogeneity of stroke brain injury, there is a clear need for a biomarker that determines the degree of neuroaxonal injury across diverse stroke types. We evaluated whether blood neurofilament light (NFL), a major component of neuronal axons, would fulfill this purpose for patients with acute cerebral infarction (ACI, N=227), aneurysmal subarachnoid hemorrhage (aSAH, N=58) or non-traumatic intracerebral hemorrhage (ICH, N=29). We additionally validated our findings in two independent cohorts of patients with ICH (N=96 and N=54) given the scarcity of blood biomarker studies for this deadliest stroke type. Compared to healthy individuals (N=79 and 48 for the discovery and validation cohorts, respectively), NFL was higher for all stroke types. NFL associated with radiographic markers of brain tissue damage. It correlated with the extent of early ischemic injury in patients with ACI, hemorrhage severity in patients with aSAH, and intracranial hemorrhage volume in patients with ICH. In all patients, NFL independently correlated with scores from the NIH Stroke Scale, the modified Rankin Scale, and the Mini-Mental State Examination at blood draw, which respectively assess neurological, functional, and cognitive status. Furthermore, higher NFL concentrations independently associated with 3- or 6-month functional disability and higher all-cause mortality. These data support NFL as a uniform method to estimate neuroaxonal injury and forecast mortality regardless of stroke mechanism. As a prognostic biomarker, blood NFL has the potential to assist with planning supportive and rehabilitation services, and improving the efficiency of acute therapeutic drug and device trials, and of recovery trials.

Spinocerebellar ataxia type 3 (SCA3), caused by a CAG repeat expansion in the ataxin-3 gene (ATXN3), is characterized by neuronal polyglutamine (polyQ) ATXN3 protein aggregates. Although there is no cure for SCA3, gene-silencing approaches to reduce toxic polyQ ATXN3 showed promise in preclinical models. However, a major limitation in translating putative treatments for this rare disease to the clinic is the lack of pharmacodynamic markers for use in clinical trials. Here, we developed an immunoassay that readily detects polyQ ATXN3 proteins in human biological fluids and discriminates patients with SCA3 from healthy controls and individuals with other ataxias. We show that polyQ ATXN3 serves as a marker of target engagement in human fibroblasts, which may bode well for its use in clinical trials. Last, we identified a single-nucleotide polymorphism that strongly associates with the expanded allele, thus providing an exciting drug target to abrogate detrimental events initiated by mutant ATXN3. Gene-silencing strategies for several repeat diseases are well under way, and our results are expected to improve clinical trial preparedness for SCA3 therapies.

Background A mutation in the C9orf72 gene is the most common genetic mutation of familial and sporadic ALS, as well as familial FTD. While prior studies have focused on elucidating the mechanisms of neuronal dysfunction and neurodegeneration associated with this genetic mutation, the contribution of microglia to disease pathogenesis in the ALS/FTD disease spectrum remains poorly understood. Methods Here, we generated a new disease model consisting of cultured C9orf72 ALS/FTD patient-derived induced pluripotent stem cells differentiated into microglia (iPSC-MG). We used this model to study the intrinsic cellular and molecular phenotypes of microglia triggered by the C9orf72 gene mutation. Results We show that C9orf72 ALS/FTD iPSC-MG have a similar transcriptional profile compared to control iPSC-MG, despite the presence of C9orf72-associated phenotypes including reduced C9orf72 protein levels and dipeptide-repeat protein translation. Interestingly, C9orf72 ALS/FTD iPSC-MG exhibit intrinsic dysfunction of phagocytic activity upon exposure to Aβ or brain synaptoneurosomes and display a heightened inflammatory response. Detailed analysis of the endosomal and lysosomal pathways revealed altered expression of endosomal marker early endosome antigen 1 and lysosomal associated membrane protein 1 in C9orf72 ALS/FTD iPSC-MG, which was confirmed in patient postmortem tissues. Conclusions These findings demonstrate that unstimulated C9orf72 iPSC-MG mono-cultures share a largely similar transcriptome profile with control microglia, despite the presence of C9orf72 disease phenotypes. The dysfunction of the endosomal-lysosomal pathway as demonstrated by aberrant microglia phagocytosis and engulfment of cellular debris and brain pathogens suggests that disease-related microglia phenotypes are not intrinsic but instead require microglia to be activated. In summary, the C9orf72 iPSC-MG culture system provides a novel human disease model to study the role of microglia in C9orf72 ALS/FTD disease pathogenesis.