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Human VCP mutant ALS/FTD microglia display immune and lysosomal phenotypes independently of GPNMB
Abstract Background Microglia play crucial roles in maintaining neuronal homeostasis but have been implicated in contributing to amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). However, the role of microglia in ALS/FTD remains incompletely understood. Methods Here, we generated highly enriched cultures of VCP mutant microglia derived from human induced pluripotent stem cells (hiPSCs) to investigate their cell autonomous and non-cell autonomous roles in ALS pathogenesis. We used RNA-sequencing, proteomics and functional assays to study hiPSC derived VCP mutant microglia and their effects on hiPSC derived motor neurons and astrocytes. Results Transcriptomic, proteomic and functional analyses revealed immune and lysosomal dysfunction in VCP mutant microglia. Stimulating healthy microglia with the inflammatory inducer lipopolysaccharide (LPS) showed partial overlap with VCP mutant microglia in their reactive transformation. LPS-stimulated VCP mutant microglia displayed differential activation of inflammatory pathways compared with LPS-stimulated healthy microglia. Conserved gene expression changes were identified between VCP mutant microglia, SOD1 mutant mice microglia, and postmortem ALS spinal cord microglial signatures, including increased expression of the transmembrane glycoprotein GPNMB. While knockdown of GPNMB affected inflammatory and phagocytosis processes in microglia, this was not sufficient to ameliorate cell autonomous phenotypes in VCP mutant microglia. Secreted factors from VCP mutant microglia were sufficient to activate the JAK-STAT pathway in hiPSC derived motor neurons and astrocytes. Conclusions VCP mutant microglia undergo cell autonomous reactive transformation involving immune and lysosomal dysfunction that partially recapitulate key phenotypes of microglia from other ALS models and post mortem tissue. These phenotypes occur independently of GPNMB. Additionally, VCP mutant microglia elicit non cell autonomous responses in motor neurons and astrocytes involving the JAK-STAT pathway.
The ALS/FTD-related C9orf72 hexanucleotide repeat expansion forms RNA condensates through multimolecular G-quadruplexes
AbstractAmyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are neurodegenerative diseases that exist on a clinico-pathogenetic spectrum, designated ALS/FTD. The most common genetic cause of ALS/FTD is expansion of the intronic hexanucleotide repeat (GGGGCC)n in C9orf72. Here, we investigate the formation of nucleic acid secondary structures in these expansion repeats, and their role in generating condensates characteristic of ALS/FTD. We observe significant aggregation of the hexanucleotide sequence (GGGGCC)n, which we associate to the formation of multimolecular G-quadruplexes (mG4s) by using a range of biophysical techniques. Exposing the condensates to G4-unfolding conditions leads to prompt disassembly, highlighting the key role of mG4-formation in the condensation process. We further validate the biological relevance of our findings by detecting an increased prevalence of G4-structures in C9orf72 mutant human motor neurons when compared to healthy motor neurons by staining with a G4-selective fluorescent probe, revealing signal in putative condensates. Our findings strongly suggest that RNA G-rich repetitive sequences can form protein-free condensates sustained by multimolecular G-quadruplexes, highlighting their potential relevance as therapeutic targets for C9orf72 mutation-related ALS/FTD.
Estimating the effectiveness of routine asymptomatic PCR testing at different frequencies for the detection of SARS-CoV-2 infections
AbstractBackgroundRoutine asymptomatic testing using RT-PCR of people who interact with vulnerable populations, such as medical staff in hospitals or care workers in care homes, has been employed to help prevent outbreaks among vulnerable populations. Although the peak sensitivity of RT-PCR can be high, the probability of detecting an infection will vary throughout the course of an infection. The effectiveness of routine asymptomatic testing will therefore depend on testing frequency and how PCR detection varies over time.MethodsWe fitted a Bayesian statistical model to a dataset of twice weekly PCR tests of UK healthcare workers performed by self-administered nasopharyngeal swab, regardless of symptoms. We jointly estimated times of infection and the probability of a positive PCR test over time following infection; we then compared asymptomatic testing strategies by calculating the probability that a symptomatic infection is detected before symptom onset and the probability that an asymptomatic infection is detected within 7 days of infection.ResultsWe estimated that the probability that the PCR test detected infection peaked at 77% (54–88%) 4 days after infection, decreasing to 50% (38–65%) by 10 days after infection. Our results suggest a substantially higher probability of detecting infections 1–3 days after infection than previously published estimates. We estimated that testing every other day would detect 57% (33–76%) of symptomatic cases prior to onset and 94% (75–99%) of asymptomatic cases within 7 days if test results were returned within a day.ConclusionsOur results suggest that routine asymptomatic testing can enable detection of a high proportion of infected individuals early in their infection, provided that the testing is frequent and the time from testing to notification of results is sufficiently fast.
Drug screening with human SMN2 reporter identifies SMN protein stabilizers to correct SMA pathology
Spinal muscular atrophy (SMA), the leading genetic cause of infant mortality, is caused by reduced levels of functional survival motor neuron (SMN) protein. To identify therapeutic agents for SMA, we established a versatile SMN2-GFP reporter line by targeting the human SMN2 gene. We then screened a compound library and identified Z-FA-FMK as a potent candidate. Z-FA-FMK, a cysteine protease inhibitor, increased functional SMN through inhibiting the protease-mediated degradation of both full-length and exon 7–deleted forms of SMN. Further studies reveal that CAPN1, CAPN7, CTSB, and CTSL mediate the degradation of SMN proteins, providing novel targets for SMA. Notably, Z-FA-FMK mitigated mitochondriopathy and neuropathy in SMA patient–derived motor neurons and showed protective effects in SMA animal model after intracerebroventricular injection. E64d, another cysteine protease inhibitor which can pass through the blood–brain barrier, showed even more potent therapeutic effects after subcutaneous delivery to SMA mice. Taken together, we have successfully established a human SMN2 reporter for future drug discovery and identified the potential therapeutic value of cysteine protease inhibitors in treating SMA via stabilizing SMN proteins.
Outcomes After Acute Plasma Exchange for Myelin Oligodendrocyte Glycoprotein Antibody-Associated Disease.
BACKGROUND AND OBJECTIVES: Data on the plasma exchange (PLEX) in myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) are limited. Herein, we evaluate outcomes after PLEX in MOGAD. METHODS: This international multicenter retrospective cohort study included patients from 18 tertiary care centers in 6 countries. Inclusion criteria included fulfillment of the 2023 International MOGAD panel criteria, receipt of at least 3 sessions of PLEX, and follow-up of ≥3 months after PLEX. Patients with coexisting neuroinflammatory disorders were excluded. We assessed the frequency of complete recovery (CR), clinically significant improvement (CSI), visual acuity (VA), and Expanded Disability Status Scale (EDSS). Logistic regression analyses were performed to identify predictors of CR and CSI. RESULTS: Of 234 patients, 135 (58%) were female. The median (interquartile range [IQR]) age at attack was 34 (IQR 22-49) years, and 42 (17%) were children. In 165 of 243 (68%), the attack treated with PLEX was the first attack. Attack phenotypes included 161 optic neuritis (235 eyes), 77 myelitis, 24 acute disseminated encephalomyelitis, 15 brainstem/cerebellar, 3 cerebral-cortical encephalitis attack, and 1 cerebral polyfocal deficit-36 with >1 core phenotypes. A total of 239 (99%) attacks were also treated with corticosteroids and 32 (13%) with IV immunoglobulins. VA in optic neuritis improved from 20/400 (20/70-hand motion) to 20/20 (20/20-20/30), p < 0.001, and EDSS decreased from a median of 4.0 (3.0-6.5) to 1.0 (0.0-2.5), p < 0.001. Of 229 attacks without subsequent attacks within 3 months, 100 (44%) achieved CR and 213 (93%) CSI. The probability of CR was decreased with advanced age (adjusted odd ratio [95% CI] 0.97 [0.96-0.99] per year), higher EDSS worsening from baseline (0.66 [0.54-0.81] per 0.5 increment) and delayed PLEX (0.98 [0.96-0.99] per day). Advanced age (0.97 [0.96-0.99] per year) and delayed PLEX (0.95 [0.94-0.96] per day) decreased the probability of CSI. DISCUSSION: We observed favorable outcomes after PLEX in MOGAD attacks. However, advanced age and delayed initiation of PLEX were associated with a reduced probability of improvement. The absence of a control group limits our ability to differentiate PLEX effects from spontaneous recovery, prior corticosteroid response, or long-term immunotherapy. Future prospective studies are needed to assess the impact of PLEX on improvement. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that PLEX is associated with favorable clinical outcomes in patients with MOGAD.
Serum biomarkers of delirium in critical illness: a systematic review of mechanistic and diagnostic evidence
Abstract Delirium is a frequent and serious complication of critical illness, yet its pathophysiological mechanisms remain incompletely understood. Serum biomarkers offer a potential avenue for improved diagnosis, risk stratification, and mechanistic insight. This systematic review synthesises evidence from 28 studies evaluating 54 serum biomarkers in relation to delirium among critically ill adult patients. Biomarkers were categorised by mechanistic pathway, including central nervous system (CNS) injury, immune activation, hormonal dysregulation, neurotransmission, coagulation, and amino acid metabolism. Among CNS injury markers, S100β and neurofilament light chain (NfL) demonstrated the most consistent associations with delirium presence and severity, supporting a role for astrocytic and axonal injury in delirium pathogenesis. Inflammatory markers such as interleukin-6 (IL-6), C-reactive protein (CRP), and tumour necrosis factor-alpha (TNF-α) were frequently studied but showed variable associations, reflecting the complex and non-specific nature of systemic inflammation. Hormonal biomarkers, including cortisol and prolactin, showed preliminary promise, while neurotransmitter-related biomarkers yielded inconsistent results, challenging canonical hypotheses. A major limitation in the literature was the lack of standardisation in delirium assessment, sampling timelines, and adjustment for confounding variables. Only a minority of studies incorporated temporal profiling or longitudinal outcomes, and replication across cohorts was limited. Heterogeneity in ICU populations further reduced generalisability. This review proposes a new conceptual framework of mechanistic endotyping, integrating multimodal biomarker profiling with clinical phenotyping to define biologically distinct subtypes of delirium. Such an approach may support precision medicine strategies by aligning therapeutic interventions with underlying pathophysiology. Future biomarker research should prioritise longitudinal sampling, harmonised protocols, and integration with EEG, imaging, and cognitive outcomes. Despite early promise, serum biomarkers for ICU delirium remain investigational and require further validation before clinical application.
Caring for Coma after Severe Brain Injury: Clinical Practices and Challenges to Improve Outcomes: An Initiative by the Curing Coma Campaign.
Severe brain injury can result in disorders of consciousness (DoC), including coma, vegetative state/unresponsive wakefulness syndrome, and minimally conscious state. Improved emergency and trauma medicine response, in addition to expanding efforts to prevent premature withdrawal of life-sustaining treatment, has led to an increased number of patients with prolonged DoC. High-quality bedside care of patients with DoC is key to improving long-term functional outcomes. However, there is a paucity of DoC-specific evidence guiding clinicians on efficacious bedside care that can promote medical stability and recovery of consciousness. This Viewpoint describes the state of current DoC bedside care and identifies knowledge and practice gaps related to patient care with DoC collated by the Care of the Patient in Coma scientific workgroup as part of the Neurocritical Care Society's Curing Coma Campaign. The gap analysis identified and organized domains of bedside care that could affect patient outcomes: clinical expertise, assessment and monitoring, timing of intervention, technology, family engagement, cultural considerations, systems of care, and transition to the post-acute continuum. Finally, this Viewpoint recommends future research and education initiatives to address and improve the care of patients with DoC.
Unique considerations in the assessment and management of traumatic brain injury in older adults.
The age-specific incidence of traumatic brain injury in older adults is rising in high-income countries, mainly due to an increase in the incidence of falls. The severity of traumatic brain injury in older adults can be underestimated because of a delay in the development of mass effect and symptoms of intracranial haemorrhage. Management and rehabilitation in older adults must consider comorbidities and frailty, the treatment of pre-existing disorders, the reduced potential for recovery, the likelihood of cognitive decline, and the avoidance of future falls. Older age is associated with worse outcomes after traumatic brain injury, but premorbid health is an important predictor and good outcomes are achievable. Although prognostication is uncertain, unsubstantiated nihilism (eg, early withdrawal decisions from the assumption that old age necessarily leads to poor outcomes) should be avoided. The absence of management recommendations for older adults highlights the need for stronger evidence to enhance prognostication. In the meantime, decision making should be multidisciplinary, transparent, personalised, and inclusive of patients and relatives.