Takotsubo cardiomyopathy in Guillain-Barré syndrome.

BACKGROUND AND PURPOSE: Takotsubo cardiomyopathy (TCM) is a serious autonomic complication of Guillain-Barré syndrome (GBS). However, the association between TCM and GBS has not been investigated in detail. We investigated the characteristics of GBS patients with TCM (GBS-TCM). METHODS: Clinical features and anti-ganglioside antibody between the GBS-TCM patients and 62 classical GBS patients without TCM as control patients were compared. RESULTS: Eight GBS-TCM patients were identified, in whom TCM was diagnosed at a mean of 6.5 [range 3-42] days after the onset of GBS. The age at onset of GBS was elder in the GBS-TCM patients than in the control GBS patients (76.5 [56-87] vs. 52 [20-88] years, p < 0.01). Notably, cranial nerve deficits, particularly in the lower cranial nerves, were observed in all GBS-TCM patients (100% vs. 41.9%, p < 0.01). Additionally, the GBS-TCM patients showed a higher GBS disability score at nadir (5 [4-5] vs. 4 [1-5], p < 0.01), and lower Medical Research Council sum scores at admission and nadir (37 [30-44] vs. 48 [12-60] at admission, p < 0.05, and 20 [12-44] vs. 40 [0-60] at nadir, p < 0.05, respectively). Mechanical ventilation was more frequently required in the GBS-TCM patients (62.5% vs. 11.3%, p < 0.01). Three GBS-TCM patients were positive for anti-ganglioside antibodies. CONCLUSIONS: TCM occurred at a relatively early phase of GBS. The characteristics of GBS-TCM were the elder, lower cranial nerve involvements, severe limb weakness, and respiratory failure.

eIF5 stimulates the CUG initiation of RAN translation of poly-GA dipeptide repeat protein (DPR) in C9orf72 FTLD/ALS.

Tandem GGGGCC repeat expansion in C9orf72 is a genetic cause of frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS). Transcribed repeats are translated into dipeptide repeat proteins via repeat-associated non-AUG (RAN) translation. However, the regulatory mechanism of RAN translation remains unclear. Here, we reveal a GTPase-activating protein, eukaryotic initiation factor 5 (eIF5), which allosterically facilitates the conversion of eIF2-bound GTP into GDP upon start codon recognition, as a novel modifier of C9orf72 RAN translation. Compared to global translation, eIF5, but not its inactive mutants, preferentially stimulates poly-GA RAN translation. RAN translation is increased during integrated stress response, but the stimulatory effect of eIF5 on poly-GA RAN translation was additive to the increase of RAN translation during integrated stress response, with no further increase in phosphorylated eIF2α. Moreover, an alteration of the CUG near cognate codon to CCG or AUG in the poly-GA reading frame abolished the stimulatory effects, indicating that eIF5 primarily acts through the CUG-dependent initiation. Lastly, in a Drosophila model of C9orf72 FTLD/ALS that expresses GGGGCC repeats in the eye, knockdown of endogenous eIF5 by two independent RNAi strains significantly reduced poly-GA expressions, confirming in vivo effect of eIF5 on poly-GA RAN translation. Together, eIF5 stimulates the CUG initiation of poly-GA RAN translation in cellular and Drosophila disease models of C9orf72 FTLD/ALS.

Dysregulation of stress granule dynamics by DCTN1 deficiency exacerbates TDP-43 pathology in Drosophila models of ALS/FTD.

The abnormal aggregation of TDP-43 into cytoplasmic inclusions in affected neurons is a major pathological hallmark of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Although TDP-43 is aberrantly accumulated in the neurons of most patients with sporadic ALS/FTD and other TDP-43 proteinopathies, how TDP-43 forms cytoplasmic aggregates remains unknown. In this study, we show that a deficiency in DCTN1, a subunit of the microtubule-associated motor protein complex dynactin, perturbs the dynamics of stress granules and drives the formation of TDP-43 cytoplasmic aggregation in cultured cells, leading to the exacerbation of TDP-43 pathology and neurodegeneration in vivo. We demonstrated using a Drosophila model of ALS/FTD that genetic knockdown of DCTN1 accelerates the formation of ubiquitin-positive cytoplasmic inclusions of TDP-43. Knockdown of components of other microtubule-associated motor protein complexes, including dynein and kinesin, also increased the formation of TDP-43 inclusions, indicating that intracellular transport along microtubules plays a key role in TDP-43 pathology. Notably, DCTN1 knockdown delayed the disassembly of stress granules in stressed cells, leading to an increase in the formation of pathological cytoplasmic inclusions of TDP-43. Our results indicate that a deficiency in DCTN1, as well as disruption of intracellular transport along microtubules, is a modifier that drives the formation of TDP-43 pathology through the dysregulation of stress granule dynamics.

The effect of rasagiline on swallowing function in Parkinson's disease.

Dysphagia, a potentially fatal symptom of Parkinson's disease, is characterized by frequent silent aspiration, a risk factor for aspiration pneumonia. The transdermal dopamine agonist rotigotine alleviates dysphagia in patients with Parkinson's disease and is more effective than oral levodopa, suggesting the importance of continuous dopaminergic stimulation during swallowing. Rasagiline is a monoamine oxidase B (MAOB) inhibitor that facilitates continuous dopaminergic stimulation. We hypothesized that MAOB inhibition by rasagiline would be effective in improving swallowing function in patients with early- and mid-to late-stage Parkinson's disease. To this end, we performed an analytical observational study to determine the effects of rasagiline (1 mg/day) on swallowing function using videofluoroscopic swallowing study. This open-label, evaluator-blinded study enrolled 32 patients with Parkinson's disease, among whom 19 were drug-naïve and 13 were receiving add-on therapy. Our results showed that rasagiline significantly improved all swallowing measures during the oral and pharyngeal phases, including oral transit time and pharyngeal transit time, in all enrolled patients. Similar results were found in drug-naïve and mid-to late-stage patients, with no intergroup differences. In conclusion, drugs capable of continuous dopaminergic stimulation may effectively improve swallowing function in patients with Parkinson's disease, with similar effects in early- and mid-to late-stage Parkinson's disease. This study has been the first to show that rasagiline significantly improves swallowing function in mid-to late-stage patients receiving add-on therapy.

Lysophagy protects against propagation of α-synuclein aggregation through ruptured lysosomal vesicles.

The neuron-to-neuron propagation of misfolded α-synuclein (αSyn) aggregates is thought to be key to the pathogenesis of synucleinopathies. Recent studies have shown that extracellular αSyn aggregates taken up by the endosomal-lysosomal system can rupture the lysosomal vesicular membrane; however, it remains unclear whether lysosomal rupture leads to the transmission of αSyn aggregation. Here, we applied cell-based αSyn propagation models to show that ruptured lysosomes are the pathway through which exogenous αSyn aggregates transmit aggregation, and furthermore, this process was prevented by lysophagy, i.e., selective autophagy of damaged lysosomes. αSyn aggregates accumulated predominantly in lysosomes, causing their rupture, and seeded the aggregation of endogenous αSyn, initially around damaged lysosomes. Exogenous αSyn aggregates induced the accumulation of LC3 on lysosomes. This LC3 accumulation was not observed in cells in which a key regulator of autophagy, RB1CC1/FIP200, was knocked out and was confirmed as lysophagy by transmission electron microscopy. Importantly, RB1CC1/FIP200-deficient cells treated with αSyn aggregates had increased numbers of ruptured lysosomes and enhanced propagation of αSyn aggregation. Furthermore, various types of lysosomal damage induced using lysosomotropic reagents, depletion of lysosomal enzymes, or more toxic species of αSyn fibrils also exacerbated the propagation of αSyn aggregation, and impaired lysophagy and lysosomal membrane damage synergistically enhanced propagation. These results indicate that lysophagy prevents exogenous αSyn aggregates from escaping the endosomal-lysosomal system and transmitting aggregation to endogenous cytosolic αSyn via ruptured lysosomal vesicles. Our findings suggest that the progression and severity of synucleinopathies are associated with damage to lysosomal membranes and impaired lysophagy.

Reconstitution of C9orf72 GGGGCC repeat-associated non-AUG translation with purified human translation factors.

Nucleotide repeat expansion of GGGGCC (G4C2) in the non-coding region of C9orf72 is the most common genetic cause underlying amyotrophic lateral sclerosis and frontotemporal dementia. Transcripts harboring this repeat expansion undergo the translation of dipeptide repeats via a non-canonical process known as repeat-associated non-AUG (RAN) translation. In order to ascertain the essential components required for RAN translation, we successfully recapitulated G4C2-RAN translation using an in vitro reconstituted translation system comprising human factors, namely the human PURE system. Our findings conclusively demonstrate that the presence of fundamental translation factors is sufficient to mediate the elongation from the G4C2 repeat. Furthermore, the initiation mechanism proceeded in a 5' cap-dependent manner, independent of eIF2A or eIF2D. In contrast to cell lysate-mediated RAN translation, where longer G4C2 repeats enhanced translation, we discovered that the expansion of the G4C2 repeats inhibited translation elongation using the human PURE system. These results suggest that the repeat RNA itself functions as a repressor of RAN translation. Taken together, our utilization of a reconstituted RAN translation system employing minimal factors represents a distinctive and potent approach for elucidating the intricacies underlying RAN translation mechanism.

Memantine administration prevented chorea movement in Huntington's disease: a case report.

BACKGROUND: Huntington's disease is an autosomal dominant inherited disorder characterized by personality changes (such as irritability and restlessness) and psychotic symptoms (such as hallucinations and delusions). When the personality changes become noticeable, involuntary movements (chorea) also develop. The disease is caused by the CAG repeat expansion in the coding region of the HTT gene, and the diagnosis is based on the presence of this expansion. However, there is currently no effective treatment for the progression of Huntington's disease and its involuntary motor symptoms. Herein, we present a case in which memantine was effective in treating the chorea movements of Huntington's disease. CASE PRESENTATION: A 75-year-old Japanese woman presented to the hospital with involuntary movements of Huntington's disease that began when she was 73 years old. In a cerebral blood flow test (N-isopropyl-p-iodoamphetamine-single-photon emission computed tomography), decreased blood flow was observed in the precuneus (anterior wedge) and posterior cingulate gyrus. Usually, such areas of decreased blood flow are observed in patients with Alzheimer's-type dementia. So, we administered memantine for Alzheimer's-type dementia, and this treatment suppressed the involuntary movements of Huntington's disease, and the symptoms progressed slowly for 7 years after the onset of senility. In contrast, her brother died of complications of pneumonia during the course of Huntington's disease. CONCLUSIONS: We recorded changes in parameters such as the results of the N-isopropyl-p-iodoamphetamine-single-photon emission computed tomography and gait videos over 7 years. Treatment with memantine prevented the chorea movement and the progression of Huntington's disease. We believe this record will provide clinicians with valuable information in diagnosing and treating Huntington's disease.

CANVAS-related RFC1 mutations in patients with immune-mediated neuropathy.

Cerebellar ataxia, neuropathy, and vestibular areflexia syndrome (CANVAS) has recently been attributed to biallelic repeat expansions in RFC1. More recently, the disease entity has expanded to atypical phenotypes, including chronic neuropathy without cerebellar ataxia or vestibular areflexia. Very recently, RFC1 expansions were found in patients with Sjögren syndrome who had neuropathy that did not respond to immunotherapy. In this study RFC1 was examined in 240 patients with acute or chronic neuropathies, including 105 with Guillain-Barré syndrome or Miller Fisher syndrome, 76 with chronic inflammatory demyelinating polyneuropathy, and 59 with other types of chronic neuropathy. Biallelic RFC1 mutations were found in three patients with immune-mediated neuropathies, including Guillain-Barré syndrome, idiopathic sensory ataxic neuropathy, or anti-myelin-associated glycoprotein (MAG) neuropathy, who responded to immunotherapies. In addition, a patient with chronic sensory autonomic neuropathy had biallelic mutations, and subclinical changes in Schwann cells on nerve biopsy. In summary, we found CANVAS-related RFC1 mutations in patients with treatable immune-mediated neuropathy or demyelinating neuropathy.

FUS regulates RAN translation through modulating the G-quadruplex structure of GGGGCC repeat RNA in C9orf72-linked ALS/FTD.

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.

The effects of safinamide on dysphagia in Parkinson's disease.

Dysphagia is a potentially fatal symptom of Parkinson's disease (PD) and is characterized by frequent silent aspiration, a risk factor for aspiration pneumonia. The transdermal dopamine agonist rotigotine alleviates dysphagia in patients with PD and is more effective than oral levodopa, suggesting the importance of continuous dopaminergic stimulation (CDS) in swallowing. Safinamide is a monoamine oxidase B (MAOB) inhibitor that facilitates CDS. In this retrospective open-label evaluator-blinded research, swallowing functions in nine patients with PD were examined using a video fluoroscopic swallowing study (VFSS) before and after treatment with 50 mg of oral safinamide. The VFSS results showed that safinamide significantly improved some swallowing measures during oral and pharyngeal phases, including oral transit time and pharyngeal transit time, without worsening of any measures. Notably, improvements in lip closure, an oral phase component, seemed to be most attributable to improvements in oral phase scores. In conclusion, a medicine for CDS may effectively improve swallowing functions in patients with PD. This is the first study to show that the MAOB inhibitor safinamide partly but significantly improves swallowing function in patients with PD.

A case of thymoma-associated myasthenia gravis accompanied with myositis showing the clusters of histiocyte along the fascicles in perimysium.

Patients with myasthenia gravis (MG) often have other autoimmune disorders. However, the coexistence of MG and myositis is rare. Here, we report a case of a 77-year-old woman who developed mild fatigable muscle weakness and diplopia in 3 months. Serum creatine kinase was elevated to 1385 IU/L. Antibodies to acetylcholine receptor (AChR), titin and voltage-gated potassium channel 1.4 (Kv 1.4) were all positive while all tested myositis-specific autoantibodies were negative. Standard needle electromyography showed fibrillation potential and early recruitment of motor units. The repetitive nerve stimulations were consistent with a disorder of the neuromuscular junction. Muscle biopsy showed that the clusters of histiocyte were present along the fascicles in perimysium and some of them invaded into endomysium.

Phosphatidylinositol-3,4,5-trisphosphate interacts with alpha-synuclein and initiates its aggregation and formation of Parkinson's disease-related fibril polymorphism.

Lipid interaction with α-synuclein (αSyn) has been long implicated in the pathogenesis of Parkinson's disease (PD). However, it has not been fully determined which lipids are involved in the initiation of αSyn aggregation in PD. Here exploiting genetic understanding associating the loss-of-function mutation in Synaptojanin 1 (SYNJ1), a phosphoinositide phosphatase, with familial PD and analysis of postmortem PD brains, we identified a novel lipid molecule involved in the toxic conversion of αSyn and its relation to PD. We first established a SYNJ1 knockout cell model and found SYNJ1 depletion increases the accumulation of pathological αSyn. Lipidomic analysis revealed SYNJ1 depletion elevates the level of its substrate phosphatidylinositol-3,4,5-trisphosphate (PIP3). We then employed Caenorhabditis elegans model to examine the effect of SYNJ1 defect on the neurotoxicity of αSyn. Mutations in SYNJ1 accelerated the accumulation of αSyn aggregation and induced locomotory defects in the nematodes. These results indicate that functional loss of SYNJ1 promotes the pathological aggregation of αSyn via the dysregulation of its substrate PIP3, leading to the aggravation of αSyn-mediated neurodegeneration. Treatment of cultured cell line and primary neurons with PIP3 itself or with PIP3 phosphatase inhibitor resulted in intracellular formation of αSyn inclusions. Indeed, in vitro protein-lipid overlay assay validated that phosphoinositides, especially PIP3, strongly interact with αSyn. Furthermore, the aggregation assay revealed that PIP3 not only accelerates the fibrillation of αSyn, but also induces the formation of fibrils sharing conformational and biochemical characteristics similar to the fibrils amplified from the brains of PD patients. Notably, the immunohistochemical and lipidomic analyses on postmortem brain of patients with sporadic PD showed increased PIP3 level and its colocalization with αSyn. Taken together, PIP3 dysregulation promotes the pathological aggregation of αSyn and increases the risk of developing PD, and PIP3 represents a potent target for intervention in PD.

Repeat-associated non-AUG translation in neuromuscular diseases: mechanisms and therapeutic insights.

Expanded short tandem repeats cause more than 50 monogenic diseases, which are mostly neuromuscular diseases. In the non-coding repeat expansion diseases, in which the expanded repeat sequence is located outside of the coding region, the toxicity of the transcribed repeat-containing RNAs had been the focus of research. However, recent studies have revealed that repeat RNAs can be translated into repeat polypeptides, despite the lack of an AUG initiation codon, by non-canonical repeat-associated non-AUG translation (RAN translation). RAN translated repeat polypeptides have actually been confirmed in patients' tissues. Moreover, various cellular and animal disease models have demonstrated the toxicity of these peptides, suggesting the pathogenic roles of RAN translation in the repeat expansion diseases. In this review, we will outline RAN translation, from the viewpoint of its molecular mechanisms to its potential as a therapeutic target for the repeat expansion diseases.

Sustained therapeutic benefits by transient reduction of TDP-43 using ENA-modified antisense oligonucleotides in ALS/FTD mice.

The abnormal aggregation of TDP-43 into cytoplasmic inclusions in affected neurons is a pathological hallmark of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Although how TDP-43 forms cytoplasmic aggregates and causes neurodegeneration in patients with ALS/FTD remains unclear, reducing cellular TDP-43 levels is likely to prevent aggregation and to rescue neurons from TDP-43 toxicity. To address this issue, here we developed gapmer-type antisense oligonucleotides (ASOs) against human TDP-43 using 2'-O,4'-C-ethylene nucleic acids (ENAs), which are modified nucleic acids with high stability, and tested the therapeutic potential of lowering TDP-43 levels using ENA-modified ASOs. We demonstrated that intracerebroventricular administration of ENA-modified ASOs into a mouse model of ALS/FTD expressing human TDP-43 results in the efficient reduction of TDP-43 levels in the brain and spinal cord. Surprisingly, a single injection of ENA-modified ASOs into TDP-43 mice led to long-lasting improvement of behavioral abnormalities and the suppression of cytoplasmic TDP-43 aggregation, even after TDP-43 levels had returned to the initial levels. Our results demonstrate that transient reduction of TDP-43 using ENA-modified ASOs leads to sustained therapeutic benefits in vivo, indicating the possibility of a disease-modifying therapy by lowering TDP-43 levels for the treatment of the TDP-43 proteinopathies, including ALS/FTD.

What repeat expansion disorders can teach us about the Central Dogma.

Pathogenic repeat sequences underlie several human disorders, including amyotrophic lateral sclerosis, Huntington's disease, and myotonic dystrophy. Here, we speak to several researchers about how repeat sequences have been implicated in affecting all aspects of the Central Dogma of molecular biology through their effects on DNA, RNA, and protein.

Characteristics of Guillain-Barré syndrome in super-elderly individuals.

BACKGROUND: Japan has the world's largest super-aging population, and the number of elderly patients with various diseases is increasing. Herein, we reported the characteristics of super-elderly patients, aged over 80 years, with Guillain-Barré syndrome (GBS), a typical neuroimmune disease. METHODS: During the period 2019-2021, 74 patients over the age of 80 years diagnosed with GBS at Kindai university were analyzed as the super-elderly group patients. The control group comprised 74 consecutive patients aged < 79 years, under the same conditions. GBS was diagnosed using Brighton diagnostic criteria. Electrophysiology was assessed using the Ho criteria. RESULTS: The mean age was 83.5 years in the super-elderly group and 51.7 years in the control group. Prior infection was recognized in 50% of cases in the super-elderly group and 77% of cases in the control group with fewer cases in the super-elderly group. The mean number of days until peak symptom presentation was longer in the super-elderly group. The percentage who required a ventilator was significantly higher among the super-elderly group than among the control group. Hughes functional grading scale was more severe in the super-elderly group. Electrophysiological examination revealed the demyelinating form was particularly common in the super-elderly group. Intravenous immunoglobulin was the most common treatment in both the groups, with no difference in efficacy. CONCLUSIONS: Super-elderly onset GBS tends to be severe, therefore it is important to diagnose and treat appropriately, even in the absence of prior episodes of infection.

Therapeutic reduction of GGGGCC repeat RNA levels by hnRNPA3 suppresses neurodegeneration in Drosophila models of C9orf72-linked ALS/FTD.

The abnormal expansion of GGGGCC hexanucleotide repeats within the C9orf72 gene is the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). The accumulation of GGGGCC repeat-containing RNAs as RNA foci, and the deposition of dipeptide repeat proteins (DPR) produced from these repeat RNAs by unconventional translation are major pathological hallmarks of C9orf72-linked ALS/FTD (C9-ALS/FTD), and are both thought to play a crucial role in the pathogenesis of these diseases. Because GGGGCC repeat RNA is likely to be the most upstream therapeutic target in the pathogenic cascade of C9-ALS/FTD, lowering the cellular level of GGGGCC repeat RNA is expected to mitigate repeat RNA toxicity, and will therefore be a disease-modifying therapeutic strategy for the treatment of C9-ALS/FTD. In this study, we demonstrated using a Drosophila model of C9-ALS/FTD that elevated expression of a subset of human RNA-binding proteins that bind to GGGGCC repeat RNA, including hnRNPA3, IGF2BP1, hnRNPA2B1, hnRNPR and SF3B3, reduces the level of GGGGCC repeat RNA, resulting in the suppression of neurodegeneration. We further showed that hnRNPA3-mediated reduction of GGGGCC repeat RNA suppresses disease pathology, such as RNA foci and DPR accumulation. These results demonstrate that hnRNPA3 and other RNA-binding proteins negatively regulate the level of GGGGCC repeat RNA, and mitigate repeat RNA toxicity in vivo, indicating the therapeutic potential of the repeat RNA-lowering approach mediated by endogenous RNA-binding proteins for the treatment of C9-ALS/FTD.

Direct evaluation of neuroaxonal degeneration with the causative genes of neurodegenerative diseases in Drosophila using the automated axon quantification system, MeDUsA.

Drosophila is an excellent model organism for studying human neurodegenerative diseases (NDs). However, there is still almost no experimental system that could directly observe the degeneration of neurons and automatically quantify axonal degeneration. In this study, we created MeDUsA (a 'method for the quantification of degeneration using fly axons'), a standalone executable computer program based on Python that combines a pre-trained deep-learning masking tool with an axon terminal counting tool. This software automatically quantifies the number of retinal R7 axons in Drosophila from a confocal z-stack image series. Using this software, we were able to directly demonstrate that axons were degenerated by the representative causative genes of NDs for the first time in Drosophila. The fly retinal axon is an excellent experimental system that is capable of mimicking the pathology of axonal degeneration in human NDs. MeDUsA rapidly and accurately quantifies axons in Drosophila photoreceptor neurons. It enables large-scale research into axonal degeneration, including screening to identify genes or drugs that mediate axonal toxicity caused by ND proteins and diagnose the pathological significance of novel variants of human genes in axons.

Comparison of serum and plasma as a source of blood extracellular vesicles: Increased levels of platelet-derived particles in serum extracellular vesicle fractions alter content profiles from plasma extracellular vesicle fractions.

Extracellular vesicles (EVs) have attracted much attention as potential diagnostic biomarkers for human diseases. Although both plasma and serum are utilized as a source of blood EVs, it remains unclear whether, how and to what extent the choice of plasma and serum affects the experimental results. To address this issue, in this study, we performed comprehensive characterization of EV fractions derived from plasma and serum, and investigated the differences between these blood EVs. We demonstrated by nanoparticle tracking analysis that EV fractions derived from serum contain more particles than those from plasma of mice. Proteomic analysis demonstrated that platelet-associated proteins are selectively enriched in serum EV fractions from both mice and humans. A literature review of proteomic data of human blood EVs reported by other groups further confirmed that selective enrichment of platelet-associated proteins is commonly observed in serum EVs, and confers different proteome profiles to plasma EVs. Our data provide experimental evidence that EV fractions derived from serum generally contain additional EVs that are released from platelets, which may qualitatively and quantitatively alter EV profiles when using serum as a source of blood EVs.

C9orf72 Hexanucleotide Repeat Expansion-Related Neuropathology Is Attenuated by Nasal Rifampicin in Mice.

The non-coding GGGGCC hexanucleotide repeat expansion (HRE) in C9orf72 gene is a dominant cause of frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). This intronic mutation elicits the formation of nuclear and cytoplasmic inclusions containing RNA, RNA-binding proteins, and HRE-derived dipeptide repeat proteins (DPRs), leading to neurodegeneration via the gain-of-toxic function or loss-of-function of relevant proteins. Using C9-500 mice harboring ~500 repeats of the GGGGCC sequence in human C9orf72 gene, we investigated the effects of rifampicin against HRE-related pathological phenotypes. Rifampicin was administered intranasally to 4.5- to 5-month-old mice for 1 month, and their cognitive function and neuropathology were assessed by the Morris water maze test and immunohistochemical staining. Rifampicin treatment reduced the formation of RNA foci and cytoplasmic inclusions containing DPRs or phosphorylated TDP-43, and furthermore, the levels of phosphorylated double-strand RNA-dependent protein kinase (PKR) that regulates repeat-associated non-ATG (RAN) translation. Synapse loss in the hippocampus and neuronal loss and microglial activation in the prefrontal and motor cortices were also attenuated, and mouse memory was significantly improved. Our findings suggest a therapeutic potential of nasal rifampicin in the prevention of C9orf72-linked neurodegenerative disorders.