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Background: Progranulin (PGRN) is a lysosomal glycoprotein implicated in various neurodegenerative diseases, including frontotemporal dementia and neuronal ceroid lipofuscinosis. Over 70 mutations discovered in the GRN gene all result in reduced expression of the PGRN protein. Genetic and functional studies point toward a regulatory role for PGRN in lysosome functions. However, the detailed molecular function of PGRN within lysosomes and the impact of PGRN deficiency on lysosomes remain unclear., Methods: We developed multifaceted proteomic techniques to characterize the dynamic lysosomal biology in living human neurons and fixed mouse brain tissues. Using lysosome proximity labeling and immuno-purification of intact lysosomes, we characterized lysosome compositions and interactome in both human induced pluripotent stem cell (iPSC)-derived glutamatergic neurons (i 3 Neurons) and mouse brains. Using dynamic stable isotope labeling by amino acids in cell culture (dSILAC) proteomics, we measured global protein half-lives in human i 3 Neurons for the first time., Results: Leveraging the multi-modal proteomics and live-cell imaging techniques, we comprehensively characterized how PGRN deficiency changes the molecular and functional landscape of neuronal lysosomes. We found that PGRN loss impairs the lysosome's degradative capacity with increased levels of v-ATPase subunits on the lysosome membrane, increased hydrolases within the lysosome, altered protein regulations related to lysosomal transport, and elevated lysosomal pH. Consistent with impairments in lysosomal function, GRN-null i 3 Neurons and frontotemporal dementia patient-derived i 3 Neurons carrying GRN mutation showed pronounced alterations in protein turnover, such as cathepsins and proteins related to supramolecular polymerization and inherited neurodegenerative diseases., Conclusion: This study suggested PGRN as a critical regulator of lysosomal pH and degradative capacity, which influences global proteostasis in neurons. Beyond the study of progranulin deficiency, these newly developed proteomic methods in neurons and brain tissues provided useful tools and data resources for the field to study the highly dynamic neuronal lysosome biology., (© 2023. The Author(s).)

TDP-43 is an RNA-binding protein with a crucial nuclear role in splicing, and mislocalises from the nucleus to the cytoplasm in a range of neurodegenerative disorders. TDP-43 proteinopathy spans a spectrum of incurable, heterogeneous, and increasingly prevalent neurodegenerative diseases, including the amyotrophic lateral sclerosis and frontotemporal dementia disease spectrum and a significant fraction of Alzheimer's disease. There are currently no directed disease-modifying therapies for TDP-43 proteinopathies, and no way to distinguish who is affected before death. It is now clear that TDP-43 proteinopathy leads to a number of molecular changes, including the de-repression and inclusion of cryptic exons. Importantly, some of these cryptic exons lead to the loss of crucial neuronal proteins and have been shown to be key pathogenic players in disease pathogenesis (e.g., STMN2), as well as being able to modify disease progression (e.g., UNC13A). Thus, these aberrant splicing events make promising novel therapeutic targets to restore functional gene expression. Moreover, presence of these cryptic exons is highly specific to patients and areas of the brain affected by TDP-43 proteinopathy, offering the potential to develop biomarkers for early detection and stratification of patients. In summary, the discovery of cryptic exons gives hope for novel diagnostics and therapeutics on the horizon for TDP-43 proteinopathies., (© 2023. The Author(s).)

Background: Niemann-Pick disease, type C (NPC) is a childhood-onset, lethal, neurodegenerative disorder caused by autosomal recessive mutations in the genes NPC1 or NPC2 and characterized by impaired cholesterol homeostasis, a lipid essential for cellular function. Cellular cholesterol levels are tightly regulated, and mutations in either NPC1 or NPC2 lead to deficient transport and accumulation of unesterified cholesterol in the late endosome/lysosome compartment, and progressive neurodegeneration in affected individuals. Previous cell-based studies to understand the NPC cellular pathophysiology and screen for therapeutic agents have mainly used patient fibroblasts. However, these do not allow modeling the neurodegenerative aspect of NPC disease, highlighting the need for an in vitro system that permits understanding the cellular mechanisms underlying neuronal loss and identifying appropriate therapies. This study reports the development of a novel human iPSC-derived, inducible neuronal model of Niemann-Pick disease, type C1 (NPC1)., Results: We generated a null i3Neuron (inducible × integrated × isogenic) (NPC1 -/- i 3 Neuron) iPSC-derived neuron model of NPC1. The NPC1 -/- and the corresponding isogenic NPC1 +/+ i 3 Neuron cell lines were used to efficiently generate homogenous, synchronized neurons that can be used in high-throughput screens. NPC1 -/- i 3 Neurons recapitulate cardinal cellular NPC1 pathological features including perinuclear endolysosomal storage of unesterified cholesterol, accumulation of GM2 and GM3 gangliosides, mitochondrial dysfunction, and impaired axonal lysosomal transport. Cholesterol storage, mitochondrial dysfunction, and axonal trafficking defects can be ameliorated by treatment with 2-hydroxypropyl-β-cyclodextrin, a drug that has shown efficacy in NPC1 preclinical models and in a phase 1/2a trial., Conclusion: Our data demonstrate the utility of this new cell line in high-throughput drug/chemical screens to identify potential therapeutic agents. The NPC1 -/- i 3 Neuron line will also be a valuable tool for the NPC1 research community to explore the pathological mechanisms contributing to neuronal degeneration., (© 2021. The Author(s).)

Background: Older people are frequent emergency department (ED) users who present with complex issues that are linked to poorer health outcomes following the index visit, often have increased ED length of stay, and tend to have raised healthcare costs. Encouraging evidence suggests that ED teams involving health and social care professionals (HSCPs) can contribute to enhanced patient flow and an improved patient experience by improving care decision-making and thus promoting timely and effective care. However, the evidence supporting the impact of HSCP teams assessing and intervening with older adults in the ED is limited and identifies important methodological limitations, highlighting the need for more robust and comprehensive investigations of this model of care. This study aims to evaluate the impact of a dedicated ED-based HSCP team on the quality, safety, and clinical- and cost-effectiveness of care of older adults when compared with usual care., Methods: The study is a single-site randomised controlled trial whereby patients aged ≥65 years who present to the ED of a large Irish hospital will be randomised to the experimental group (ED-based HSCP assessment and intervention) or the control group (usual ED care). The recruitment target is 320 participants. The HSCP team will provide a comprehensive functional assessment as well as interventions to promote a safe discharge for the patient. The primary outcome is ED length of stay (from arrival to discharge). Secondary outcomes include: rates of hospital admissions from the ED, ED re-visits, unplanned hospital admissions and healthcare utilisation at 30 days, and 4 and 6 months of follow-up; patient functional status and quality of life (at baseline and follow-up); patient satisfaction; cost-effectiveness in terms of costs associated with ED-based HSCP compared with usual care; and perceptions on implementation by ED staff members., Discussion: This is the first randomised controlled trial testing the impact of HSCPs working in teams in the ED on the quality, safety, and clinical- and cost-effectiveness of care for older patients. The findings of this study will provide important information on the effectiveness of this model of care for future implementation., Trial Registration: ClinicalTrials.gov, NCT03739515 . Registered on 12 November 2018.

Background: Early warning score systems have been widely recommended for use to detect clinical deterioration in patients. The Irish National Emergency Medicine Programme has developed and piloted an emergency department specific early warning score system. The objective of this study was to develop a consensus among frontline healthcare staff, quality and safety staff and health systems researchers regarding evaluation measures for an early warning score system in the Emergency Department., Methods: Participatory action research including a modified Delphi consensus building technique with frontline hospital staff, quality and safety staff, health systems researchers, local and national emergency medicine stakeholders was the method employed in this study. In Stage One, a workshop was held with the participatory action research team including frontline hospital staff, quality and safety staff and health systems researchers to gather suggestions regarding the evaluation measures. In Stage Two, an electronic modified-Delphi study was undertaken with a panel consisting of the workshop participants, key local and national emergency medicine stakeholders. Descriptive statistics were used to summarise the characteristics of the panellists who completed the questionnaires in each round. The mean Likert rating, standard deviation and 95% bias-corrected bootstrapped confidence interval for each variable was calculated. Bonferroni corrections were applied to take account of multiple testing. Data were analysed using Stata 14.0 SE., Results: Using the Institute for Healthcare Improvement framework, 12 process, outcome and balancing metrics for measuring the effectiveness of an ED-specific early warning score system were developed., Conclusion: There are currently no published measures for evaluating the effectiveness of an ED early warning score system. It was possible in this study to develop a suite of evaluation measures using a modified Delphi consensus approach. Using the collective expertise of frontline hospital staff, quality and safety staff and health systems researchers to develop and categorise the initial set of potential measures was an innovative and unique element of this study.

Background: Research on team effectiveness in healthcare has focussed on whether effective teams yield positive outcomes for patients and on the effectiveness of team interventions to improve performance. Limited understanding exists of what works for whom within an effective team, or how and why the context in which the team operates enables team members both as individuals and as a collective to enact behaviours that promote positive outcomes., Methods: This realist synthesis of the literature explores the relationship between team interventions, underlying teamwork mechanisms generated by those interventions, and the resultant impact on patient outcomes in an acute hospital context. A systematic search of five healthcare and healthcare management academic databases: PubMed, PsychINFO, CINAHL, ABInform, Emerald Management and three grey literature databases: ERIC, OpenDOAR and Open Grey was undertaken. Five experts in the field were also contacted to source relevant literature. Using PRISMA guidelines, relevant studies published between January 2006 and January 2017 were systematically searched by a team of three people. Drawing on realist methodology, data were synthesised using context, mechanism and outcome configurations as the unit of analysis to identify enablers and barriers to effective team interventions., Results: Out of 3347 papers retrieved, 18 were included in the final synthesis. From these, five contextual enablers were identified: an inter-disciplinary focus and flattened hierarchy; effective communication; leadership support and alignment of team goals with organisational goals; credibility of intervention; and appropriate team composition with physician involvement. Ten recurring mechanisms were identified, the most frequently occurring of which was shared responsibility., Conclusions: The advantage of using realist synthesis to extrapolate data from the literature is that it considers the context and mechanisms that will impact effectiveness of healthcare team interventions. This methodological approach provides a different perspective to other types of syntheses and offers insight as to why certain contextual elements may yield more success than others. Findings therefore tend to have more practical implications. Specificity of detail in terms of how external drivers impact on healthcare team interventions was limited in the articles extracted for analysis. This broader perspective is therefore an important consideration for future research.

Background: Microglia, the resident immune cells of the brain, have been implicated in brain injury and various neurological disorders. However, their precise roles in different pathophysiological situations remain enigmatic and may range from detrimental to protective. Targeting the delivery of biologically active compounds to microglia could help elucidate these roles and facilitate the therapeutic modulation of microglial functions in neurological diseases., Methods: Here we employ primary cell cultures and stereotaxic injections into mouse brain to investigate the cell type specific localization of semiconductor quantum dots (QDs) in vitro and in vivo. Two potential receptors for QDs are identified using pharmacological inhibitors and neutralizing antibodies., Results: In mixed primary cortical cultures, QDs were selectively taken up by microglia; this uptake was decreased by inhibitors of clathrin-dependent endocytosis, implicating the endosomal pathway as the major route of entry for QDs into microglia. Furthermore, inhibiting mannose receptors and macrophage scavenger receptors blocked the uptake of QDs by microglia, indicating that QD uptake occurs through microglia-specific receptor endocytosis. When injected into the brain, QDs were taken up primarily by microglia and with high efficiency. In primary cortical cultures, QDs conjugated to the toxin saporin depleted microglia in mixed primary cortical cultures, protecting neurons in these cultures against amyloid beta-induced neurotoxicity., Conclusions: These findings demonstrate that QDs can be used to specifically label and modulate microglia in primary cortical cultures and in brain and may allow for the selective delivery of therapeutic agents to these cells.