Association of APOE genotype and cerebrospinal fluid Aß and tau biomarkers with cognitive and motor phenotype in amyotrophic lateral sclerosis.

OBJECTIVE: Little is known about amyotrophic lateral sclerosis (ALS)-nonspecific cognitive deficits - most notably memory disturbance - and their biological underpinnings. We investigated the associations of the Alzheimer's disease (AD) genetic risk factor APOE and cerebrospinal fluid (CSF) biomarkers Aß and tau proteins with cognitive and motor phenotype in ALS. METHODS: APOE haplotype was determined in 281 ALS patients; for 105 of these, CSF levels of Aß42, Aß40, total tau (T-tau), and phosphorylated tau (P-tau181) were quantified by chemiluminescence enzyme immunoassay (CLEIA). The Edinburgh Cognitive and Behavioural ALS Screen (ECAS) was employed to evaluate the neuropsychological phenotype. RESULTS: APOE-E4 allele was associated with worse ECAS memory score (median, 14.0 in carriers vs. 16.0 in non-carriers) and lower CSF Aß42 (-0.8 vs. 0.1, log-transformed values) and Aß42/40 ratio (-0.1 vs. 0.3). Some 37.1% of ALS patients showed low Aß42 levels, possibly reflecting cerebral Aß deposition. While lower Aß42/40 correlated with lower memory score (ß = 0.20), Aß42 positively correlated with both ALS-specific (ß = 0.24) and ALS-nonspecific (ß = 0.24) scores. Although Aß42/40 negatively correlated with T-tau (ß = -0.29) and P-tau181 (ß = -0.33), we found an unexpected positive association of Aß42 and Aß40 with both tau proteins. Regarding motor phenotype, lower levels of Aß species were associated with lower motor neuron (LMN) signs (Aß40: ß = 0.34; Aß42: ß = 0.22). CONCLUSIONS: APOE haplotype and CSF Aß biomarkers are associated with cognitive deficits in ALS and particularly with memory impairment. This might partly reflect AD-like pathophysiological processes, but additional ALS-specific mechanisms could be involved.

Altered nuclear envelope homeostasis is a key pathogenic event in C9ORF72-linked ALS/FTD.

ALS and FTD are complex neurodegenerative disorders that primarily affects motor neurons in the brain and spinal cord, and cortical neurons in the frontal lobe. Although the pathogenesis of ALS/FTD is unclear, recent research spotlights nucleocytoplasmic transport impairment, DNA damage, and nuclear abnormalities as drivers of neuronal death. In this study, we show that loss of nuclear envelope (NE) integrity is a key pathology associated with nuclear pore complex (NPC) injury in C9ORF72 mutant neurons. Importantly, we show that mechanical stresses generated by cytoskeletal forces on the NE can lead to NPC injury, loss of nuclear integrity, and accumulation of DNA damage. Importantly, we demonstrate that restoring NE tensional homeostasis, by disconnecting the nucleus from the cytoskeleton, can rescue NPC injury and reduce DNA damage in C9ORF72 mutant cells. Together, our data suggest that modulation of NE homeostasis and repair may represent a novel and promising therapeutic target for ALS/FTD.

Analysis of normal C9orf72 repeat length as possible disease modifier in amyotrophic lateral sclerosis.

The C9orf72 hexanucleotide repeat (HR) expansion is the main genetic cause of amyotrophic lateral sclerosis (ALS), with expansion size from 30 to >4000 units. Normal C9orf72 HR length is polymorphic (2-23 repeats) with alleles >8 units showing a low frequency in the general population. This study aimed to investigate if the normal C9orf72 HR length influences C9orf72 gene expression and acts as disease modifier in ALS patients negative for C9orf72 mutation (ALS-C9Neg). We found that the distribution of HR alleles was similar in 325 ALS-C9Neg and 303 healthy controls. Gene expression analysis in blood revealed a significant increase of total C9orf72 and V3 mRNA levels in ALS-C9Neg carrying two long alleles (L/L; ≥8 units) compared to patients homozygous for the 2-unit short allele (S/S). However, HR allele genotypes (L/L, S/L, S/S) correlated with no clinical parameters. Our data suggest that normal C9orf72 HR length does not act as disease modifier in ALS-C9Neg despite increasing gene expression.

Generation of five induced pluripotent stem cells lines from four members of the same family carrying a C9orf72 repeat expansion and one wild-type member.

The most common genetic cause of Amyotrophic Lateral Sclerosis (ALS) is the expansion of a G4C2 hexanucleotide repeat in the C9orf72 gene. The size of the repeat expansion is highly variable and a cut-off of 30 repeats has been suggested as the lower pathological limit. Repeat size variability has been observed intergenerationally and intraindividually in tissues from different organs and within the same tissue, suggesting instability of the pathological repeat expansion. In order to study this genomic instability, we established iPSCs from five members of the same family of which four carried a C9orf72 repeat expansion and one was wild-type.

Generation of an iPSC line from a patient with spastic paraplegia type 10 carrying a novel mutation in KIF5A gene.

We generated an iPSC line from a patient with spastic paraplegia type 10 (SPG10) carrying the novel missense variant c.50G > A (p.R17Q) in the N-terminal motor domain of the kinesin family member 5A (KIF5A) gene. This patient-derived in vitro cell model will help to investigate the role of different KIF5A mutations in inducing neurodegeneration in spastic paraplegia and in other KIF5A-related disorders, including Charcot-Marie-Tooth type 2 (CMT2) and amyotrophic lateral sclerosis (ALS).

Human motor neurons derived from induced pluripotent stem cells are susceptible to SARS-CoV-2 infection.

Introduction: COVID-19 typically causes Q7 respiratory disorders, but a high proportion of patients also reports neurological and neuromuscular symptoms during and after SARSCoV-2 infection. Despite a number of studies documenting SARS-CoV-2 infection of various neuronal cell populations, the impact of SARS-CoV-2 exposure on motor neuronal cells specifically has not been investigated so far. Methods: Thus, by using human iPSC-derived motor neurons (iPSC-MNs) we assessed: (i) the expression of SARS-CoV-2 main receptors; (ii) iPSC-MN infectability by SARS-CoV-2; and (iii) the effect of SARS-CoV-2 exposure on iPSC-MN transcriptome. Results: Gene expression profiling and immunofluorescence (IF) analysis of the main host cell receptors recognized by SARS-CoV-2 revealed that all of them are expressed in iPSC-MNs, with CD147 and NRP1 being the most represented ones. By analyzing SARS-CoV-2 N1 and N2 gene expression over time, we observed that human iPSC-MNs were productively infected by SARS-CoV-2 in the absence of cytopathic effect. Supernatants collected from SARS-CoV-2-infected iPSC-MNs were able to re-infect VeroE6 cells. Image analyses of SARS-CoV-2 nucleocapsid proteins by IF confirmed iPSC-MN infectability. Furthermore, SARS-CoV-2 infection in iPSCMNs significantly altered the expression of genes (IL-6, ANG, S1PR1, BCL2, BAX, Casp8, HLA-A, ERAP1, CD147, MX1) associated with cell survival and metabolism, as well as antiviral and inflammatory response. Discussion: These results suggest for the very first time that SARS-CoV-2 can productively infect human iPSC-derived MNs probably by binding CD147 and NRP1 receptors. Such information will be important to unveil the biological bases of neuromuscular disorders characterizing SARS-CoV-2 infection and the so called long-COVID symptoms.