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Background: Alzheimer's disease (AD) is a progressive neurodegenerative disorder neuropathologically characterized by amyloid‐β (Aβ) plaques and neurofibrillary tangles. Assessment of AD‐related endophenotypes can reveal novel insights into aspects of the heterogeneity of AD. We hypothesize that, amongst AD patients, the levels and solubility of AD‐related proteins are influenced by genetic variants; identifying these may provide key insights into disease pathogenesis. To test this, we performed a genome‐wide association study (GWAS) for the levels of five AD‐related proteins (apoE, Aβ40, Aβ42, tau, and p‐tau) in the brain. Methods: Genome‐wide genotypes were collected from 441 autopsy‐confirmed AD cases on the Infinium Omni2.5Exome‐8 v1.3 genotyping array, imputed to the haplotype reference consortium (HRC) panel, and quality filtered. Temporal cortex levels of the five AD‐related proteins from three fractions, i.e. buffer‐soluble (TBS), detergent‐soluble (Triton‐X=TX), and insoluble (Formic acid=FA) were measured by ELISA. Using linear regression, genetic variants were tested for association with each biochemical measure, and the Aβ40/42 ratio. Pathway analysis was done using GSA‐SNP2 to identify enriched Gene Ontology (GO) terms. Results: We identified 9 unique GWS variants (genome‐wide significant, p<2.89E‐08), 2 at the APOE locus and 7 novel. Variants within the APOE locus were significantly associated with Aβ40 levels in the TX and FA fractions, the Aβ40/42 ratio in the FA fraction, and apoE levels in the TBS and FA fractions. Of the novel GWS variants, four were associated with Aβ40 residing on chromosomes 17 (TBS), 3, 4, and 15 (TX), and three with apoE levels on chromosomes 19 (TBS), 7, and 14 (TX). Pathway analysis revealed both shared and distinct pathways significantly enriched for the GWAS results. Conclusions: Although all biochemical measures tested reflect proteins core to AD pathology, our results strongly suggest each have unique genetic factors and enriched pathways which influence their brain levels. Furthermore, discovery of genetic factors that underlie specific biochemical outcomes may lead to the identification of novel genes that influence biochemical properties of AD proteins. These findings can enhance our understanding of the pathophysiology of proteostasis in AD and may have implications for other neurodegenerative diseases also characterized by abnormal protein accumulation in the brain. [ABSTRACT FROM AUTHOR]

Background: Tau neurofibrillary tangles and senile plaques comprised of insoluble amyloid beta are the major histopathological hallmarks of Alzheimer's disease (AD). More than 85% of autopsy‐confirmed AD cases also exhibit some degree of cerebral amyloid angiopathy (CAA), which is characterized by amyloid beta peptide deposits predominantly in blood vessels in the meningeal and intracerebral blood vessels. Consequently, CAA predisposes individuals with AD to cerebral infarction and hemorrhages, accounting for ∼20% of cases in the elderly, which could lead to faster cognitive decline through neurovascular pathway dysfunction. We sought to identify cellular composition changes and characterize cell type‐specific expression associated with CAA pathology in AD patients. Methods: Using 10x Genomics single nuclei RNA sequencing, we profiled nuclei from frozen post‐mortem temporal cortex tissue of 80 individuals with neuropathologic diagnosis of AD and varying levels of CAA, ranging from zero to severe CAA pathology. Braak and Thal measures were also obtained. Downstream analyses were performed in R using Seurat v3.2.3. Quality control filtering based on percentage of genes mapped to the mitochondrial genome and number of genes and UMIs detected resulted in 135,092 nuclei for analysis. Differential gene expression analyses were performed using R package MAST. Results: We identified 30 clusters which were annotated using established cell type marker genes. There were 3 oligodendrocyte, 14 neuronal (2 excitatory and 3 inhibitory), 5 microglial, 3 endothelial, 4 astrocyte and 1 oligodendrocyte precursor cell cluster. We observed a significant increase in microglial cell proportions with increasing CAA severity, for 3 of the microglial clusters. Conversely, the excitatory neuronal proportion were decreased in individuals with more severe CAA. Further investigation is ongoing to identify the genes underlying the dysregulation of these cell types in CAA. Conclusion: We observed cellular proportion changes for multiple cell types with increasing CAA severity. Additional analyses to determine the effects of CAA independent of AD severity will be performed by adjusting for Braak and Thal measures. Deeper characterization of cell type‐specific expression profiles is expected to provide novel insights into cell‐type specific transcriptome changes associated with vascular risk factors in AD. [ABSTRACT FROM AUTHOR]

Aggregation of amyloid-β (Aβ) peptides leads to synaptic disruption and neurodegeneration in Alzheimer disease (AD). A major Aβ clearance pathway in the brain is cellular uptake and degradation. However, how Aβ traffics through the endocytic pathway and how AD risk factors regulate this event is unclear. Here we show that the majority of endocytosed Aβ in neurons traffics through early and late endosomes to the lysosomes for degradation. Overexpression of Rab5 or Rab7, small GTPases that function in vesicle fusion for early and late endosomes, respectively, significantly accelerates Aβ endocytic trafficking to the lysosomes. We also found that a portion of endocytosed Aβ traffics through Rab11-positive recycling vesicles. A blockage of this Aβ recycling pathway with a constitutively active Rab11 mutant significantly accelerates cellular Aβ accumulation. Inhibition of lysosomal enzymes results in Aβ accumulation and aggregation. Importantly, apolipoprotein E (apoE) accelerates neuronal Aβ uptake, lysosomal trafficking, and degradation in an isoform-dependent manner with apoE3 more efficiently facilitating Aβ trafficking and degradation than apoE4, a risk factor for AD. Taken together, our results demonstrate that Aβ endocytic trafficking to lysosomes for degradation is a major Aβ clearance pathway that is differentially regulated by apoE isoforms. A disturbance of this pathway can lead to accumulation and aggregation of cellular Aβ capable of causing neurotoxicity and seeding amyloid. [ABSTRACT FROM AUTHOR]

Impaired clearance of amyloid-ß (Aß) is a major pathogenic event for Alzheimer's disease (AD). Aß depositions in brain parenchyma as senile plaques and along cerebrovasculature as cerebral amyloid angiopathy (CAA) are hallmarks of AD. A major pathway that mediates brain Aß clearance is the cerebrovascular system where Aß is eliminated through the blood-brain barrier (BBB) and/or degraded by cerebrovascular cells along the interstitial fluid drainage pathway. An Aß clearance receptor, the low-density lipoprotein receptor-related protein 1 (LRPl), is abundantly expressed in cerebrovasculature, in particular in vascular smooth muscle cells. Previous studies have indicated a role of LRPl in endothelial cells in transcytosing Aß out of the brain across the BBB; however, whether this represents a significant pathway for brain Aß clearance remains controversial. Here, we demonstrate that Aß can be cleared locally in the cerebrovasculature by an LRPl-dependent endocytic pathway in smooth muscle cells. The uptake and degradation of both endogenous and exogenous Aß were significantly reduced in LRP1 -suppressed human brain vascular smooth muscle cells. Conditional deletion of Lrpl in vascular smooth muscle cell in amyloid model APP/PS1 mice accelerated brain Aß accumulation and exacerbated Aß deposition as amyloid plaques and CAA without affecting Aß production. Our results demonstrate that LRPl is a major Aß clearance receptor in cerebral vascular smooth muscle cell and a disturbance of this pathway contributes to Aß accumulation. These studies establish critical functions of the cerebrovasculature system in Aß metabolism and identify a new pathway involved in the pathogenesis of both AD and CAA. [ABSTRACT FROM AUTHOR]

Mutations in the presenilin-1 (PSEN1) gene are associated with familial Alzheimer's disease and frontotemporal dementia (FTD). Interestingly, neuropathological analysis of a Belgian FTD family carrying a PSEN1 c.548G>T mutation confirmed neurodegeneration in the absence of amyloid plaques. To investigate the impact of the c.548G>T mutation on presenilin-1 (PS1) function in vivo, we introduced this mutation into the genomic Psen1 locus. The resulting c.548G>T knock-in (KI) mice are viable but express markedly lower levels of PsenmRNAand protein in the brain. This reduction is due to production of aberrantly spliced transcripts lacking either exon 6 or exons 6 and 7 and their subsequent degradation via non-sense-mediated decay (NMD); inhibition of NMD by cycloheximide treatment stabilized these transcripts and restored the level of Psen1 mRNA in KI/KI brains. Interestingly, the reduction of Psen1 mRNA expression and the degradation of aberrant Psen1 splice products occur exclusively in the brain but not in other tissues. Consistent with decreased Psen1 expression, -secretase activity was strongly reduced in the cerebral cortex of KI mice, as measured by de novo -secretase-mediated cleavage of APP and Notch. Moreover, PS1 expressed from Psen1 cDNA carrying the c.548G>T mutation displayed normal -secretase activity in cultured cells, indicating that the corresponding p.183GVaminoacid substitution does not affect-secretase activity. Finally, Psen1 c.548G>TKI/KI;Psen2/ mice exhibited mild spatial memory deficits in the Morris water maze task. Together, our findings demonstrate that the c.548G>T mutation results in a brain-specific loss of presenilin function due to decreased Psen1mRNAexpression. [ABSTRACT FROM AUTHOR]

Alzheimer's disease (AD) is a progressive and irreversible neurodegenerative disorder in which the aggregation and deposition of amyloid-β (Aβ) peptides in the brain are central to its pathogenesis. In healthy brains, Aβ is effectively metabolized with little accumulation. Cellular uptake and subsequent degradation of Aβ is one of the major pathways for its clearance in the brain. Increasing evidence has demonstrated significant roles for the low-density lipoprotein receptor-related protein 1 (LRP1) in the metabolism of Aβ in neurons, glia cells, and along the brain vasculatures. Heparan sulfate proteoglycan (HSPG) has also been implicated in several pathogenic features of AD, including its colocalization with amyloid plaques. Here, we demonstrate that HSPG and LRP1 cooperatively mediate cellular Aβ uptake. Fluorescence-activated cell sorter and confocal microscopy revealed that knockdown of LRP1 suppresses Aβ uptake, whereas overexpression of LRP1 enhances this process in neuronal cells. Heparin, which antagonizes HSPG, significantly inhibited cellular Aβ uptake. Importantly, treatment with heparin or heparinase blocked LRP1-mediated cellular uptake of Aβ. We further showed that HSPG is more important for the binding of Aβ to the cell surface than LRP1. The critical roles of HSPG in cellular Aβ binding and uptake were confirmed in Chinese hamster ovary cells genetically deficient in HSPG. We also showed that heparin and a neutralizing antibody to LRP1 suppressed Aβ uptake in primary neurons. Our findings demonstrate that LRP1 and HSPG function in a cooperative manner to mediate cellular Aβ uptake and define a major pathway through which Aβ gains entry to neuronal cells. [ABSTRACT FROM AUTHOR]

Prostaglandin D2 (PGD) is synthesized by hematopoietic PGD synthase (HPGDS) or lipocalin-type PGDS (L-PGDS), depending on the organ in which it is produced, and binds specifically to either DP1 or DP2 receptors. We investigated the role of PGD2 in the pathogenesis of hypoxic-ischemic encephalopathy (HIE) in neonatal mice at postnatal day 7. In wild-type mice, hypoxia-ischemia increased PGD2 production in the brain up to 90-fold compared with the level in sham-operated brains at 10 min after cessation of hypoxia. Whereas the size of the infarct was not changed in L-PGDS or DP2 knock-out mouse brains compared with that in the wild-type HIE brains, it was significantly increased in HPGDS-L-PGDS double knock-out or DP1 knock-out mice. The PGD2 level in L-PGDS, HPGDS, and HPGDS-LPGDS knock-out mice at 10 min of reoxygenation was 46, 7, and 1%, respectively, of that in the wild-type ones, indicating the infarct size to be in inverse relation to the amount of PGD2 production. DP1 receptors were exclusively expressed in endothelial cells after 1 h of reoxygenation, and cerebral blood flow decreased more rapidly after the onset of hypoxia and did not return to the baseline level after reoxygenation in HPGDS-L-PGDS knock-out mice. Endothelial cells were severely damaged in HPGDS-L-PGDS and DP1 knock-out mice after 1 h of reoxygenation. In the human neonatal HIE brain, HPGDS-positive microglia were increased in number. In conclusion, it is probable that PGD2 protected the neonatal brain from hypoxic-ischemic injury mainly via DP1 receptors by preventing endothelial cell degeneration. [ABSTRACT FROM AUTHOR]

The hAβ-KI and APPSAA-KI are two amyloid models that harbor mutations in the endogenous mouse App gene. Both hAβ-KI and APPSAA-KI mice contain a humanized Aβ sequence, and APPSAA-KI mice carry three additional familial AD mutations. We herein report that the Aβ levels and Aβ42/Aβ40 ratio in APPSAA-KI homozygotes are dramatically higher than those in hAβ-KI homozygotes at 14 months of age. In addition, APPSAA-KI mice display a widespread distribution of amyloid plaques in the brain, whereas the plaques are undetectable in hAβ-KI mice. Moreover, there are no sex differences in amyloid pathology in APPSAA-KI mice. Both APPSAA-KI and hAβ-KI mice exhibit cognitive impairments, wherein no significant differences are found between these two models, although APPSAA KI mice show a trend towards worse cognitive function. Notably, female hAβ-KI and APPSAA-KI mice have a more pronounced cognitive impairments compared to their respective males. Our findings suggest that Aβ humanization contributes to cognitive deficits in APPSAA-KI mice, and that amyloid deposition might not be closely associated with cognitive impairments in APPSAA-KI mice. • Aβ levels in APPSAA-KI mice are dramatically higher than those in hAβ-KI mice. • Aβ42/Aβ40 ratio in APPSAA-KI mice is higher than those in hAβ-KI mice. • No sex differences in Aβ levels and amyloid plaque burden in APPSAA-KI mice. • Insoluble Aβ levels are higher in male than female hAβ-KI mice. • Aβ humanization contributes to cognitive deficits in APPSAA-KI mice. [ABSTRACT FROM AUTHOR]

Wu and Dong et al. 1 report that hepatic soluble epoxide hydrolase (sEH) manipulation impacts amyloid-β (Aβ) deposits and cognitive impairment in mouse models for Alzheimer's disease (AD), suggesting that hepatic sEH activity is a promising therapeutic target to treat AD. Wu and Dong et al.1 report that hepatic soluble epoxide hydrolase (sEH) manipulation impacts amyloid-β (Aβ) deposits and cognitive impairment in mouse models for Alzheimer's disease (AD), suggesting that hepatic sEH activity is a promising therapeutic target to treat AD. [ABSTRACT FROM AUTHOR]

The limitations imposed on brain therapy by the blood–brain barrier (BBB) have warranted the development of carriers that can overcome and deliver therapeutic agents into the brain. We strategically designed liposomal nanoparticles encasing plasmid DNA for efficient transfection and translocation across the in vitro BBB model as well as in vivo brain-targeted delivery. Liposomes were surface modified with two ligands, cell-penetrating peptide (PFVYLI or R9F2) for enhanced internalization into cells and transferrin (Tf) ligand for targeting transferrin-receptor expressed on brain capillary endothelial cells. Dual-modified liposomes encapsulating pDNA demonstrated significantly (P < 0.05) higher in vitro transfection efficiency compared to single-modified nanoparticles. R9F2Tf-liposomes showed superior ability to cross in vitro BBB and, subsequently, transfect primary neurons. Additionally, these nanoparticles crossed in vivo BBB and reached brain parenchyma of mice (6.6%) without causing tissue damage. Transferrin receptor-targeting with enhanced cell penetration is a relevant strategy for efficient brain-targeted delivery of genes. Dual-modified liposomes surface modified with cell-penetrating peptides (PFVYLI and R9F2) and transferrin ligand were designed to overcome the blood brain barrier and efficiently deliver a plasmid DNA into the brain of mice. Our results showed the superior ability of R9F2Tf-liposomes to translocate across the in vitro blood brain barrier model and transfect neuronal cells as well as enhanced in vivo brain-targeted delivery properties. Thus, R9F2Tf-liposomes have potential as a carrier for brain-targeted gene delivery. Unlabelled Image [ABSTRACT FROM AUTHOR]

Background Recent studies of patients with intracerebral hemorrhage suggest an association between peripheral blood neutrophil-lymphocyte ratio and neurologic deterioration. We aimed to study the prognostic utility of neutrophil-lymphocyte ratio in predicting inpatient mortality in aneurysmal subarachnoid hemorrhage. Methods We conducted a retrospective electronic medical record review of the clinical, laboratory, and radiographic data of patients with aneurysmal subarachnoid hemorrhage 18 years of age or older presenting to the neuroscience intensive care unit from January 1, 2011, to December 31, 2017. Patients with aneurysmal subarachnoid hemorrhage were divided into 2 groups (group 1, alive at discharge; group 2, deceased prior to discharge), and neutrophil-lymphocyte ratio laboratory mean values were recorded for each patient. Our primary outcome measure was inpatient mortality, and our secondary measure was incidence of pneumonia with hospitalization. Results We identified 403 patients with aneurysmal subarachnoid hemorrhage for the study. After exclusion criteria, 44 eligible patients were divided into the 2 groups (group 1, n = 32; group 2, n = 12). Mean neutrophil-lymphocyte ratio for group 1 was 11.53, and for group 2, 17.85 (P < .01). The mean neutrophil-lymphocyte ratio of those who developed pneumonia compared to those who did not was 15.28 versus 12.81, respectively (P = .39). A Kaplan-Meier plot demonstrated increased mortality among patients with a neutrophil-lymphocyte ratio equal to or greater than 12.5 compared to those with a neutrophil-lymphocyte ratio less than 12.5. Conclusions These preliminary data demonstrate that a neutrophil-lymphocyte ratio equal to or greater than 12.5 at admission predict higher inpatient mortality in patients with aneurysmal subarachnoid hemorrhage. [ABSTRACT FROM AUTHOR]

Apolipoprotein E (apoE) is linked to the risk for Alzheimer's disease (AD) and thus has been suggested to be an important therapeutic target. In our drug screening effort, we identified Ondansetron (OS), an FDA-approved 5-HT3 antagonist, as an apoE-modulating drug. OS at low micromolar concentrations significantly increased apoE secretion from immortalized astrocytes and primary astrocytes derived from apoE3 and apoE4-targeted replacement mice without generating cellular toxicity. Other 5-HT3 antagonists also had similar effects as OS, though their effects were milder and required higher concentrations. Antagonists for other 5-HT receptors did not increase apoE secretion. OS also increased mRNA and protein levels of the ATB-binding cassette protein A1 (ABCA1), which is involved in lipidation and secretion of apoE. Accordingly, OS increased high molecular weight apoE. Moreover, the liver X receptor (LXR) and ABCA1 antagonists blocked the OS-induced increase of apoE secretion, indicating that the LXR-ABCA1 pathway is involved in the OS-mediated facilitation of apoE secretion from astrocytes. The effects of OS on apoE and ABCA1 were also observed in human astrocytes derived from induced pluripotent stem cells (iPSC) carrying the APOE ε3/ε3 and APOE ε4/ε4 genotypes. Oral administration of OS at clinically-relevant doses affected apoE levels in the liver, though the effects in the brain were not observed. Collectively, though further studies are needed to probe its effects in vivo, OS could be a potential therapeutic drug for AD by modulating poE metabolism through the LXR-ABCA1 pathway. [ABSTRACT FROM AUTHOR]

Background: Radiation therapy is the standard of care for central nervous system tumours. Despite the success of radiation therapy in reducing tumour mass, irradiation (IR)-induced vasculopathies and neuroinflammation contribute to late-delayed complications, neurodegeneration, and premature ageing in long-term cancer survivors. Mesenchymal stromal cells (MSCs) are adult stem cells that facilitate tissue integrity, homeostasis, and repair. Here, we investigated the potential of the iPSC-derived MSC (iMSC) secretome in immunomodulation and vasculature repair in response to radiation injury utilizing human cell lines. Methods: We generated iPSC-derived iMSC lines and evaluated the potential of their conditioned media (iMSC CM) to treat IR-induced injuries in human monocytes (THP1) and brain vascular endothelial cells (hCMEC/D3). We further assessed factors in the iMSC secretome, their modulation, and the molecular pathways they elicit. Results: Increasing doses of IR disturbed endothelial tube and spheroid formation in hCMEC/D3. When IR-injured hCMEC/D3 (IR ≤ 5 Gy) were treated with iMSC CM, endothelial cell viability, adherence, spheroid compactness, and proangiogenic sprout formation were significantly ameliorated, and IR-induced ROS levels were reduced. iMSC CM augmented tube formation in cocultures of hCMEC/D3 and iMSCs. Consistently, iMSC CM facilitated angiogenesis in a zebrafish model in vivo. Furthermore, iMSC CM suppressed IR-induced NFκB activation, TNF-α release, and ROS production in THP1 cells. Additionally, iMSC CM diminished NF-kB activation in THP1 cells cocultured with irradiated hCMEC/D3, iMSCs, or HMC3 microglial lines. The cytokine array revealed that iMSC CM contains the proangiogenic and immunosuppressive factors MCP1/CCL2, IL6, IL8/CXCL8, ANG (Angiogenin), GROα/CXCL1, and RANTES/CCL5. Common promoter regulatory elements were enriched in TF-binding motifs such as androgen receptor (ANDR) and GATA2. hCMEC/D3 phosphokinome profiling revealed increased expression of pro-survival factors, the PI3K/AKT/mTOR modulator PRAS40 and β-catenin in response to CM. The transcriptome analysis revealed increased expression of GATA2 in iMSCs and the enrichment of pathways involved in RNA metabolism, translation, mitochondrial respiration, DNA damage repair, and neurodevelopment. Conclusions: The iMSC secretome is a comodulated composite of proangiogenic and immunosuppressive factors that has the potential to alleviate radiation-induced vascular endothelial cell damage and immune activation. [ABSTRACT FROM AUTHOR]

Background: Mesenchymal stromal cells (MSCs) have a dynamic secretome that plays a critical role in tissue repair and regeneration. However, studying the MSC secretome in mixed-culture disease models remains challenging. This study aimed to develop a mutant methionyl-tRNA synthetase-based toolkit (MetRSL274G) to selectively profile secreted proteins from MSCs in mixed-culture systems and demonstrate its potential for investigating MSC responses to pathological stimulation. Methods: We used CRISPR/Cas9 homology-directed repair to stably integrate MetRSL274G into cells, enabling the incorporation of the non-canonical amino acid, azidonorleucine (ANL), and facilitating selective protein isolation using click chemistry. MetRSL274G was integrated into both in H4 cells and induced pluripotent stem cells (iPSCs) for a series of proof-of-concept studies. Following iPSC differentiation into induced-MSCs, we validated their identity and co-cultured MetRSL274G-expressing iMSCs with naïve or lipopolysaccharide (LPS)-treated THP-1 cells. We then profiled the iMSC secretome using antibody arrays. Results: Our results showed successful integration of MetRSL274G into targeted cells, allowing specific isolation of proteins from mixed-culture environments. We also demonstrated that the secretome of MetRSL274G-expressing iMSCs can be differentiated from that of THP-1 cells in co-culture and is altered when co-cultured with LPS-treated THP-1 cells compared to naïve THP-1 cells. Conclusions: The MetRSL274G-based toolkit we have generated enables selective profiling of the MSC secretome in mixed-culture disease models. This approach has broad applications for examining not only MSC responses to models of pathological conditions, but any other cell type that can be differentiated from iPSCs. This can potentially reveal novel MSC-mediated repair mechanisms and advancing our understanding of tissue regeneration processes. [ABSTRACT FROM AUTHOR]

The prevalence of Alzheimer's disease is greater in women, but the underlying mechanisms remain to be elucidated. We herein demonstrated that α-secretase ADAM10 was downregulated and ADAM10 inhibitor sFRP1 was upregulated in 5xFAD mice. While there were no sex effects on ADAM10 protein and sFRP1 mRNA levels, female 5xFAD and age-matched non-transgenic mice exhibited higher levels of sFRP1 protein than corresponding male mice. Importantly, female 5xFAD mice accumulated more Aβ than males, and sFRP1 protein levels were positively associated with Aβ42 levels in 5xFAD mice. Our study suggests that sFRP1 is associated with amyloid pathology in a sex-dependent manner. [ABSTRACT FROM AUTHOR]

Background: The apolipoprotein E (APOE) gene is the strongest genetic risk factor for Alzheimer's disease (AD); however, how it modulates brain homeostasis is not clear. The apoE protein is a major lipid carrier in the brain transporting lipids such as cholesterol among different brain cell types. Methods: We generated three-dimensional (3-D) cerebral organoids from human parental iPSC lines and its isogenic APOE-deficient (APOE−/−) iPSC line. To elucidate the cell-type-specific effects of APOE deficiency in the cerebral organoids, we performed scRNA-seq in the parental and APOE−/− cerebral organoids at Day 90. Results: We show that APOE deficiency in human iPSC-derived cerebral organoids impacts brain lipid homeostasis by modulating multiple cellular and molecular pathways. Molecular profiling through single-cell RNA sequencing revealed that APOE deficiency leads to changes in cellular composition of isogenic cerebral organoids likely by modulating the eukaryotic initiation factor 2 (EIF2) signaling pathway as these events were alleviated by the treatment of an integrated stress response inhibitor (ISRIB). APOE deletion also leads to activation of the Wnt/β-catenin signaling pathway with concomitant decrease of secreted frizzled-related protein 1 (SFRP1) expression in glia cells. Importantly, the critical role of apoE in cell-type-specific lipid homeostasis was observed upon APOE deletion in cerebral organoids with a specific upregulation of cholesterol biosynthesis in excitatory neurons and excessive lipid accumulation in astrocytes. Relevant to human AD, APOE4 cerebral organoids show altered neurogenesis and cholesterol metabolism compared to those with APOE3. Conclusions: Our work demonstrates critical roles of apoE in brain homeostasis and offers critical insights into the APOE4-related pathogenic mechanisms. [ABSTRACT FROM AUTHOR]

Vascular cognitive impairment and dementia (VCID) is commonly caused by vascular injuries in cerebral large and small vessels and is a key driver of age-related cognitive decline. Severe VCID includes post-stroke dementia, subcortical ischemic vascular dementia, multi-infarct dementia, and mixed dementia. While VCID is acknowledged as the second most common form of dementia after Alzheimer's disease (AD) accounting for 20% of dementia cases, VCID and AD frequently coexist. In VCID, cerebral small vessel disease (cSVD) often affects arterioles, capillaries, and venules, where arteriolosclerosis and cerebral amyloid angiopathy (CAA) are major pathologies. White matter hyperintensities, recent small subcortical infarcts, lacunes of presumed vascular origin, enlarged perivascular space, microbleeds, and brain atrophy are neuroimaging hallmarks of cSVD. The current primary approach to cSVD treatment is to control vascular risk factors such as hypertension, dyslipidemia, diabetes, and smoking. However, causal therapeutic strategies have not been established partly due to the heterogeneous pathogenesis of cSVD. In this review, we summarize the pathophysiology of cSVD and discuss the probable etiological pathways by focusing on hypoperfusion/hypoxia, blood–brain barriers (BBB) dysregulation, brain fluid drainage disturbances, and vascular inflammation to define potential diagnostic and therapeutic targets for cSVD. [ABSTRACT FROM AUTHOR]

Neurodevelopmental disorders (NDDs) have arisen as one of the most prevailing chronic diseases within the US. Often associated with severe adverse impacts on the formation of vital central and peripheral nervous systems during the neurodevelopmental process, NDDs are comprised of a broad spectrum of disorders, such as autism spectrum disorder, attention deficit hyperactivity disorder, and epilepsy, characterized by progressive and pervasive detriments to cognitive, speech, memory, motor, and other neurological functions in patients. However, the heterogeneous nature of NDDs poses a significant roadblock to identifying the exact pathogenesis, impeding accurate diagnosis and the development of targeted treatment planning. A computational NDDs model holds immense potential in enhancing our understanding of the multifaceted factors involved and could assist in identifying the root causes to expedite treatment development. To tackle this challenge, we introduce optimal neurotrophin concentration to the driving force and degradation of neurotrophin to the synaptogenesis process of a 2D phase field neuron growth model using isogeometric analysis to simulate neurite retraction and atrophy. The optimal neurotrophin concentration effectively captures the inverse relationship between neurotrophin levels and neuron survival, while its degradation regulates concentration levels. Leveraging dynamic domain expansion, the model efficiently expands the domain based on outgrowth patterns to minimize degrees of freedom. Based on truncated T-splines, our model simulates the evolving process of complex neurite structures by applying local refinement adaptively to the cell/neurite boundary. Furthermore, a thorough parameter investigation is conducted with detailed comparisons against neuron cell cultures in experiments, enhancing our fundamental understanding of the possible mechanisms underlying NDDs. [ABSTRACT FROM AUTHOR]

Genome-wide association studies (GWASs) have identified genetic loci associated with the risk of Alzheimer's disease (AD), but the molecular mechanisms by which they confer risk are largely unknown. We conducted a metabolome-wide association study (MWAS) of AD-associated loci from GWASs using untargeted metabolic profiling (metabolomics) by ultraperformance liquid chromatography-mass spectrometry (UPLC-MS). We identified an association of lactosylceramides (LacCer) with AD-related single-nucleotide polymorphisms (SNPs) in ABCA7 (P = 5.0 × 1025 to 1.3 × 10244). We showed that plasma LacCer concentrations are associated with cognitive performance and genetically modified levels of LacCer are associated with AD risk. We then showed that concentrations of sphingomyelins, ceramides, and hexosylceramides were altered in brain tissue from Abca7 knockout mice, compared with wild type (WT) (P = 0.049-1.4 × 1025), but not in a mouse model of amyloidosis. Furthermore, activation of microglia increases intracellular concentrations of hexosylceramides in part through induction in the expression of sphingosine kinase, an enzyme with a high control coefficient for sphingolipid and ceramide synthesis. Our work suggests that the risk for AD arising from functional variations in ABCA7 is mediated at least in part through ceramides. Modulation of their metabolism or downstream signaling may offer new therapeutic opportunities for AD. [ABSTRACT FROM AUTHOR]

Background: The aggregation and spread of α-synuclein (α-Syn) protein and related neuronal toxicity are the key pathological features of Parkinson's disease (PD) and Lewy body dementia (LBD). Studies have shown that pathological species of α-Syn and tau can spread in a prion-like manner between neurons, although these two proteins have distinct pathological roles and contribute to different neurodegenerative diseases. It is reported that the low-density lipoprotein receptor-related protein 1 (LRP1) regulates the spread of tau proteins; however, the molecular regulatory mechanisms of α-Syn uptake and spread, and whether it is also regulated by LRP1, remain poorly understood. Methods: We established LRP1 knockout (LRP1-KO) human induced pluripotent stem cells (iPSCs) isogenic lines using a CRISPR/Cas9 strategy and generated iPSC-derived neurons (iPSNs) to test the role of LRP1 in α-Syn uptake. We treated the iPSNs with fluorescently labeled α-Syn protein and measured the internalization of α-Syn using flow cytometry. Three forms of α-Syn species were tested: monomers, oligomers, and pre-formed fibrils (PFFs). To examine whether the lysine residues of α-Syn are involved in LRP1-mediated uptake, we capped the amines of lysines on α-Syn with sulfo-NHS acetate and then measured the internalization. We also tested whether the N-terminus of α-Syn is critical for LRP1-mediated internalization. Lastly, we investigated the role of Lrp1 in regulating α-Syn spread with a neuronal Lrp1 conditional knockout (Lrp1-nKO) mouse model. We generated adeno-associated viruses (AAVs) that allowed for distinguishing the α-Syn expression versus spread and injected them into the hippocampus of six-month-old Lrp1-nKO mice and the littermate wild type (WT) controls. The spread of α-Syn was evaluated three months after the injection. Results: We found that the uptake of both monomeric and oligomeric α-Syn was significantly reduced in iPSNs with LRP1-KO compared with the WT controls. The uptake of α-Syn PFFs was also inhibited in LRP1-KO iPSNs, albeit to a much lesser extent compared to α-Syn monomers and oligomers. The blocking of lysine residues on α-Syn effectively decreased the uptake of α-Syn in iPSNs and the N-terminus of α-Syn was critical for LRP1-mediated α-Syn uptake. Finally, in the Lrp1-nKO mice, the spread of α-Syn was significantly reduced compared with the WT littermates. Conclusions: We identified LRP1 as a key regulator of α-Syn neuronal uptake, as well as an important mediator of α-Syn spread in the brain. This study provides new knowledge on the physiological and pathological role of LRP1 in α-Syn trafficking and pathology, offering insight for the treatment of synucleinopathies. [ABSTRACT FROM AUTHOR]

Cerebral amyloid angiopathy (CAA) contributes to accelerated cognitive decline in Alzheimer's disease (AD) dementia and is a common finding at autopsy. The APOEε4 allele and male sex have previously been reported to associate with increased CAA in AD. To inform biomarker and therapeutic target discovery, we aimed to identify additional genetic risk factors and biological pathways involved in this vascular component of AD etiology. We present a genome-wide association study of CAA pathology in AD cases and report sex- and APOE-stratified assessment of this phenotype. Genome-wide genotypes were collected from 853 neuropathology-confirmed AD cases scored for CAA across five brain regions, and imputed to the Haplotype Reference Consortium panel. Key variables and genome-wide genotypes were tested for association with CAA in all individuals and in sex and APOEε4 stratified subsets. Pathway enrichment was run for each of the genetic analyses. Implicated loci were further investigated for functional consequences using brain transcriptome data from 1,186 samples representing seven brain regions profiled as part of the AMP-AD consortium. We confirmed association of male sex, AD neuropathology and APOEε4 with increased CAA, and identified a novel locus, LINC-PINT, associated with lower CAA amongst APOEε4-negative individuals (rs10234094-C, beta = −3.70 [95% CI −0.49—−0.24]; p = 1.63E-08). Transcriptome profiling revealed higher LINC-PINT expression levels in AD cases, and association of rs10234094-C with altered LINC-PINT splicing. Pathway analysis indicates variation in genes involved in neuronal health and function are linked to CAA in AD patients. Further studies in additional and diverse cohorts are needed to assess broader translation of our findings. [ABSTRACT FROM AUTHOR]

Effective transport of therapeutic nucleic acid to brain has been a challenge for the success of gene therapy for treating brain diseases. In this study, we proposed liposomal nanoparticles modified with brain targeting ligandsfor active brain targeting with enhanced BBB permeation and delivery of genes to brain. We targeted transferrin and nicotinic acetylcholine receptors by conjugating transferrin (Tf) and rabies virus glycoprotein (RVG) peptide to surface of liposomes. Liposomal formulations showed homogeneous particle size and ability to protect plasmid DNA against enzymatic degradation. These nanoparticles were internalized by brain endothelial cells, astrocytes and primary neuronal cells through energy-dependent endocytosis pathways. RVG-Tf coupled liposomes showed superior ability to transfect cells compared to liposomes without surface modification or single modification. Characterization of permeability through blood brain barrier (BBB) and functionality of designed liposomes were performed using an in vitro triple co-culture BBB model. Liposome-RVG-Tf efficiently translocated across in vitro BBB model and, consecutively, transfected primary neuronal cells. Notably, brain-targeted liposomes promoted in vivo BBB permeation. These studies suggest that modifications of liposomes with brain-targeting ligands are a promising strategy for delivery of genes to brain. [ABSTRACT FROM AUTHOR]

Abstract Gene therapy has become a promising approach for neurodegenerative disease treatment, however there is an urgent need to develop an efficient gene carrier to transport gene across the blood brain barrier (BBB). In this study, we strategically designed dual functionalized liposomes for efficient neuronal transfection by combining transferrin (Tf) receptor targeting and enhanced cell penetration utilizing penetratin (Pen). A triple cell co-culture model of BBB confirmed the ability of the liposomes to cross the barrier layer and transfect primary neuronal cells. In vivo quantification of PenTf-liposomes demonstrated expressive accumulation in the brain (12%), without any detectable cellular damage or morphological change. The efficacy of these nanoparticles containing plasmid β-galactosidase in modulating transfection was assessed by β-galactosidase expression in vivo. As a consequence of accumulation in the brain, PenTf-liposomes significantly induced gene expression in mice. Immunofluorescence studies of brain sections of mice after tail vein injection of liposomes encapsulating pDNA encoding GFP (pGFP) illustrate the superior ability of dual-functionalized liposomes to accumulate in the brain and transfect neurons. Taken together, the multifunctional liposomes provide an excellent gene delivery platform for neurodegenerative diseases. Graphical abstract Unlabelled Image Highlights • Dual-functionalized liposomes were designed to cross BBB and deliver gene to brain cells • The designed liposomes preferentially accumulated in the brain compared to liposomes with single or no modification • PenTf-liposome carrying chitosan-gene complexes significantly induced gene transfection and protein expression in the brain • PenTf liposomal formulation is a promising gene delivery platform for treatment of neurodegenerative diseases [ABSTRACT FROM AUTHOR]

Pericytes are a major component of cerebrovasculature playing a key role in maintaining cerebrovascular homeostasis. These cells have also been suggested to regulate brain metabolism of amyloid-β (Aβ), disturbances of which are believed to contribute to the pathogenesis of Alzheimer's disease (AD). To examine the effects of pericytes on brain Aβ metabolism, C3H/10T1/2 mouse mesenchymal stem cells were differentiated into pericytes and stereotaxically injected into the brains of amyloid AD model APP/PS1 mice at the age of 18 to 20 months. Consistent with a role of pericytes in modulating cerebrovascular function, brain microcirculation in the pericyte-injected hemisphere of the mice was increased 3 weeks after implantation compared to the contralateral hemisphere when measured by laser speckle contrast analysis technology. Importantly, enzyme-linked immunosorbent assay revealed that the levels of insoluble Aβ40 and Aβ42 were significantly lower in the hippocampus of the pericyte-injected hemisphere of the APP/PS1 mice than that of the contralateral side. Consistently, immunohistochemical analysis demonstrated that the pericyte implantation reduced Aβ deposition in the hippocampus. When brain slices from the APP/PS1 mice were incubated with C3H/10T1/2 cell-derived pericytes, Aβ42 levels were significantly reduced in a manner that depends on the expression of a major Aβ endocytic receptor, the low-density lipoprotein receptor-related protein 1 (LRP1). While LRP1 mediated the cellular uptake of Aβ in the pericytes, the amounts of major Aβ-degrading enzymes were not affected by LRP1 knockdown. Together, our findings indicate that mesenchymal stem cell–derived pericytes have the capacity to reduce brain Aβ and related pathology, and suggest that cell-based therapy through transplantation of pericytes may be a promising approach to prevent and/or treat AD. [ABSTRACT FROM AUTHOR]

Aging is accompanied by increased neuroinflammation, synaptic dysfunction, and cognitive deficits both in rodents and humans, yet the onset and progression of these deficits throughout the life span remain unknown. These aging-related deficits affect the quality of life and present challenges to our aging society. Here, we defined age-dependent and progressive impairments of synaptic and cognitive functions and showed that reducing astrocyte-related neuroinflammation through anti-inflammatory drug treatment in aged mice reverses these events. By comparing young (3 months), middle-aged (18 months), aged (24 months), and advanced-aged wild-type mice (30 months), we found that the levels of an astrocytic marker, glial fibrillary acidic protein, progressively increased after 18 months of age, which preceded the decreases of the synaptic marker PSD-95. Hippocampal long-term potentiation was also suppressed in an age-dependent manner, where significant deficits were observed after 24 months of age. Fear conditioning tests demonstrated that associative memory in the context and cued conditions was decreased starting at the ages of 18 and 30 months, respectively. When the mice were tested on hidden platform water maze, spatial learning memory was significantly impaired after 24 months of age. Importantly, subacute treatment with the anti-inflammatory drug ibuprofen suppressed astrocyte activation and restored synaptic plasticity and memory function in advanced-aged mice. These results support the critical contribution of aging-related inflammatory responses to hippocampal-dependent cognitive function and synaptic plasticity, in particular during advanced aging. Our findings provide strong evidence that suppression of neuroinflammation could be a promising treatment strategy to preserve cognition during aging. [ABSTRACT FROM AUTHOR]

Apolipoprotein E (apoE) plays a critical role in maintaining synaptic integrity by transporting cholesterol to neurons through the low-density lipoprotein receptor related protein-1 (LRP1). Bexarotene, a retinoid X receptor (RXR) agonist, has been reported to have potential beneficial effects on cognition by increasing brain apoE levels and lipidation. To investigate the effects of bexarotene on aging-related synapse loss and the contribution of neuronal LRP1 to the pathway, forebrain neuron-specific LRP1 knockout ( nLrp1 − / − ) and littermate control mice were administered with bexarotene-formulated diet (100 mg/kg/day) or control diet at the age of 20–24 months for 8 weeks. Upon bexarotene treatment, levels of brain apoE and ATP-binding cassette sub-family A member 1 (ABCA1) were significantly increased in both mice. While levels of PSD95, glutamate receptor 1 (GluR1), and N-methyl- d -aspartate receptor NR1 subunit (NR1), which are key postsynaptic proteins that regulate synaptic plasticity, were decreased with aging, they were restored by bexarotene treatment in the brains of control but not nLrp1 − / − mice. These results indicate that the beneficial effects of bexarotene on synaptic integrity depend on the presence of neuronal LRP1. However, we also found that bexarotene treatment led to the activation of glial cells, weight loss and hepatomegaly, which are likely due to hepatic failure. Taken together, our results demonstrate that apoE-targeted treatment through the RXR pathway has a potential beneficial effect on synapses during aging; however, the therapeutic application of bexarotene requires extreme caution due to its toxic side effects. [ABSTRACT FROM AUTHOR]

Alzheimer's disease (AD) is a prevalent neurodegenerative condition characterized by the aggregation of amyloid-β plaques and neurofibrillary tangles in the brain, leading to synaptic dysfunction and neuronal degeneration. Recently, new treatment approaches involving drugs such as donanemab and lecanemab have been introduced for AD. However, these drug regimens have been associated with adverse effects, leading to the exploration of gene therapy as a potential treatment option. The apolipoprotein E (ApoE) isoforms (ApoE2, ApoE3, and ApoE4) play pivotal roles in AD pathology, with ApoE2 known for its protective effects against AD, making it a promising candidate for gene therapy interventions. However, delivering therapeutics across the blood-brain barrier (BBB) remains a crucial challenge in treating neurological disorders. Liposomes, lipid-based vesicles, are effective nanocarriers due to their ability to shield therapeutics from degradation, though they often lack specificity for brain delivery. To address this issue, liposomes were functionalized with cell-penetrating peptides such as penetratin (Pen), cingulin (Cgn), and a targeting ligand transferrin (T f ). This modification strategy aimed to enhance the delivery of therapeutic ApoE2 plasmids across the BBB to neurons, thereby increasing the level of ApoE2 protein expression. Experimental findings demonstrated that dual-functionalized liposomes (CgnT f and PenT f ) exhibited higher cellular uptake, biodistribution, and transfection efficiency than single-functionalized (Pen, Cgn, or T f ) and nonfunctionalized liposomes. In vitro studies using primary neuronal cells, bEnd.3 cells, and primary astrocytes consistently supported these findings. Following a single dose treatment via tail vein administration in C57BL6/J mice, in vivo biodistribution results showed significantly higher biodistribution levels in the brain (∼12% ID/gram of tissue) for dual-functionalized liposomes. Notably, treatment with dual-functionalized liposomes resulted in a 2-fold increase in ApoE2 expression levels compared to baseline levels. These findings highlight the potential of dual-functionalized liposomes as an efficacious delivery system for ApoE2 gene therapy in AD, highlighting a promising strategy to address the disease's underlying mechanisms.

Mesenchymal stromal cell (MSC) therapy has regenerative potentials to treat various pathological conditions including neurological diseases. MSCs isolated from various organs can differentiate into specific cell types to repair organ damages. However, their paracrine mechanisms are predicted to predominantly mediate their immunomodulatory, proangiogenic, and regenerative properties. While preclinical studies highlight the significant potential of MSC therapy in mitigating neurological damage from stroke and traumatic brain injury, the variability in clinical trial outcomes may stem from the inherent heterogeneity of somatic MSCs. Accumulating evidence has demonstrated that induced pluripotent stem cells (iPSCs) are an ideal alternative resource for the unlimited expansion and biomanufacturing of MSCs. Thus, we investigated how iPSC-derived MSCs (iMSCs) influence properties of iPSC-derived neurons. Our findings demonstrate that the secretome from iMSCs possesses neurotrophic effects, improving neuronal survival and promoting neuronal outgrowth and synaptic activity in vitro. Additionally, the iMSCs enhance metabolic activity via mitochondrial respiration in neurons, both in vitro and in mouse models. Glycolytic pathways also increased following the administration of iMSC secretome to iPSC-derived neurons. Consistently, in vivo experiments showed that intravenous administration of iMSCs compensated for the elevated energetic demand in male mice with irradiation-induced brain injury by restoring synaptic metabolic activity during acute brain damage. 18 F-FDG PET imaging also detected an increase in brain glucose uptake following iMSC administration. Together, our results highlight the potential of iMSC-based therapy in treating neuronal damage in various neurological disorders, while paving the way for future research and potential clinical applications of iMSCs in regenerative medicine., Competing Interests: The authors declare no competing financial interests., (Copyright © 2024 Kawatani et al.)

Subacute sclerosing panencephalitis (SSPE) is a lethal neurological disorder occurring several years after measles. Reconstruction of the evolution of the measles virus (MeV) genome in an SSPE case suggested that the matrix (M) protein mutation M-F50S, when added to other mutations, drove neuropathogenesis. However, whether and how M-F50S would promote spread independently from other mutations was in question. We investigated here the cell specificity of MeV spread in this brain and documented that both neurons and astrocytes were heavily infected. We then generated recombinant MeV with individual mutations in the three proteins of the viral membrane fusion apparatus, M, fusion (F), and hemagglutinin (H). These viruses reached similar titers as the parental wild-type virus, kept the respective mutations upon passage, and infected cells expressing the tissue-specific MeV receptors SLAM and nectin-4 with similar efficiencies. However, after inoculation of receptor-negative neurons and astrocytes differentiated from human induced pluripotent stem cells, only MeV M-F50S spread with moderate efficiency; the parental virus and its derivatives coding for a hyperfusogenic F protein, or for a cytoplasmic tail-mutated H protein, did not spread. When delivered to primary mouse neurons by cell-mediated neurite overlay, MeV M-F50S frequently reached the cell bodies and occasionally formed small infectious centers, while the other MeV reached the cell bodies only sporadically. These results demonstrate that, in neuronal cell cultures, M-F50S can enable receptor-independent spread in the absence of other mutations, and validate the inference that this single amino acid change initiated ubiquitous MeV brain spread.IMPORTANCEMeasles virus (MeV), a non-integrating negative-strand RNA virus, rarely causes subacute sclerosing panencephalitis (SSPE) several years after acute infection. During brain adaptation, the MeV genome acquires multiple mutations reducing the dependence of its membrane fusion apparatus (MFA) from an activating receptor. It was proposed that one of these mutations, matrix protein F50S, drove neuropathogenesis in an SSPE case. We report here that, in two types of neuronal cultures, a recombinant MeV with only this mutation gained receptor-independent spread, whereas viruses expressing MFA proteins with other mutations acquired during brain adaptation did not. Our results validate the inference that M-F50S initiated ubiquitous MeV brain spread resulting in lethal disease. They also prompt studies of the impact of analogous amino acid changes of the M proteins of other nonsegmented negative-strand RNA viruses on their interactions with membrane lipids and cytoskeletal components.

Importance: Vaginal fibroblast function is altered in people with pelvic organ prolapse. Thus, it is important to study vaginal fibroblasts to better understand the pathophysiology of prolapse., Objective: This study aimed to compare 3 culturing methods of primary vaginal fibroblasts., Study Design: This was an in vitro study. Patients who were undergoing surgery for vaginal prolapse were recruited. Excess vaginal epithelial tissue that would have otherwise been discarded was collected. The vaginal fibroblasts from each participant were cultured via (1) 3-hour digest, (2) coverslip, and (3) gelatin-coat methods. Differences in the efficiency of cell isolation, expression of known fibroblast-associated genes, and cellular function were compared between the 3 methods using one-way analysis of variance and Tukey test for post hoc pairwise comparisons (P < 0.05)., Results: Five patients with pelvic organ prolapse were recruited. Fibroblasts cultured via the 3-hour digest method became confluent within 3-5 days in a 100-mm dish compared to 2-3 weeks in a 6-well dish for the coverslip and gelatin-coat methods. Cells from all culture methods expressed similar amounts of vimentin and α smooth muscle actin. There were no significant differences in morphology; gene expression levels of MMP1, MMP2, ACTA2, COL1A1, COL3A1, and LOXL1 on qPCR; cell viability; proliferation; and migration between the 3 culturing methods., Conclusion: Culturing primary vaginal fibroblasts via the 3-hour digest, coverslip, and gelatin-coat methods similarly resulted in reliable primary vaginal fibroblast growth and function., Competing Interests: The authors have declared they have no conflicts of interest., (Copyright © 2024 American Urogynecologic Society. All rights reserved.)

Alzheimer's disease (AD) is the most common cause of late-life dementia characterized by progressive neurodegeneration and brain deposition of amyloid-β (Aβ) and phosphorylated tau. The APOE ε2 encoding apolipoprotein E ( APOE2 ) is a protective allele against AD among the three genotypes ( APOE ε2, ε3, ε4), while APOE4 is the strongest genetic factor substantially increasing AD risk. APOE regulates brain lipid homeostasis and maintaining synaptic plasticity and neuronal function, where APOE2 has a superior function compared to APOE3 and APOE4 . Gene therapy that increases APOE2 levels in the brain is, therefore, a promising therapeutic strategy for AD treatment. We previously reported that PEGylated liposomes conjugated with transferrin and a cell-penetrating peptide Penetratin sufficiently deliver chitosan-APOE2 cDNA plasmid complex into the brain of wild-type mice. Here, we investigated how brain-targeting liposome-based  APOE2  gene delivery influences Aβ-related pathologies in amyloid model  App NL-G-F  knockin mice at 12-month-old. We found a trend of reductions of insoluble Aβ levels in the mouse cortices 1 month after APOE2 gene therapy. Furthermore, in the App NL-G-F knockin mice that received the APOE2 gene therapy, brain transcriptome analysis through RNA-sequencing identified the upregulation of genes/pathways related to neuronal development. This was supported by increases of Dlg4 and Syp mRNAs coding synaptic proteins in the experimental group. On the other hand, we found that APOE2 gene delivery increased soluble Aβ levels, including oligomers, as well as exacerbated neurite dystrophy and decreased synaptophysin. Together, our results suggest that brain-targeting liposome-based APOE2 gene therapy is potentially beneficial for synaptic formation at the transcriptional level. Forced APOE2 expressions, however, may exacerbate Aβ toxicity by increasing the dissociation of Aβ oligomers from aggregates in the presence of considerable amyloid burden., Competing Interests: The authors declare no competing interests., (© 2024 The Authors.)

Aggregated α-synuclein (α-SYN) proteins, encoded by the SNCA gene, are hallmarks of Lewy body disease (LBD), affecting multiple brain regions. However, the specific mechanisms underlying α-SYN pathology in cortical neurons, crucial for LBD-associated dementia, remain unclear. Here, we recapitulated α-SYN pathologies in human induced pluripotent stem cells (iPSCs)-derived cortical organoids generated from patients with LBD with SNCA gene triplication. Single-cell RNA sequencing, combined with functional and molecular validation, identified synaptic and mitochondrial dysfunction in excitatory neurons exhibiting high expression of the SNCA gene, aligning with observations in the cortex of autopsy-confirmed LBD human brains. Furthermore, we screened 1280 Food and Drug Administration-approved drugs and identified four candidates (entacapone, tolcapone, phenazopyridine hydrochloride, and zalcitabine) that inhibited α-SYN seeding activity in real-time quaking-induced conversion assays with human brains, reduced α-SYN aggregation, and alleviated mitochondrial dysfunction in SNCA triplication organoids and excitatory neurons. Our findings establish human cortical LBD models and suggest potential therapeutic drugs targeting α-SYN aggregation for LBD.

Genetic variants in ABCA7, an Alzheimer's disease (AD)-associated gene, elevate AD risk, yet its functional relevance to the etiology is unclear. We generated a CRISPR-Cas9-mediated abca7 knockout zebrafish to explore ABCA7's role in AD. Single-cell transcriptomics in heterozygous abca7 +/- knockout combined with Aβ42 toxicity revealed that ABCA7 is crucial for neuropeptide Y (NPY), brain-derived neurotrophic factor (BDNF), and nerve growth factor receptor (NGFR) expressions, which are crucial for synaptic integrity, astroglial proliferation, and microglial prevalence. Impaired NPY induction decreased BDNF and synaptic density, which are rescuable with ectopic NPY. In induced pluripotent stem cell-derived human neurons exposed to Aβ42, ABCA7 -/- suppresses NPY. Clinical data showed reduced NPY in AD correlated with elevated Braak stages, genetic variants in NPY associated with AD, and epigenetic changes in NPY, NGFR, and BDNF promoters linked to ABCA7 variants. Therefore, ABCA7-dependent NPY signaling via BDNF-NGFR maintains synaptic integrity, implicating its impairment in increased AD risk through reduced brain resilience., Competing Interests: Declaration of interests C.K. is a co-founder, shareholder, and scientific advisor of Neuron-D GmbH, which had no financial involvement in or influence on this study., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Introduction: The apolipoprotein E gene (APOE) is an established central player in the pathogenesis of Alzheimer's disease (AD), with distinct apoE isoforms exerting diverse effects. apoE influences not only amyloid-beta and tau pathologies but also lipid and energy metabolism, neuroinflammation, cerebral vascular health, and sex-dependent disease manifestations. Furthermore, ancestral background may significantly impact the link between APOE and AD, underscoring the need for more inclusive research., Methods: In 2023, the Alzheimer's Association convened multidisciplinary researchers at the "AAIC Advancements: APOE" conference to discuss various topics, including apoE isoforms and their roles in AD pathogenesis, progress in apoE-targeted therapeutic strategies, updates on disease models and interventions that modulate apoE expression and function., Results: This manuscript presents highlights from the conference and provides an overview of opportunities for further research in the field., Discussion: Understanding apoE's multifaceted roles in AD pathogenesis will help develop targeted interventions for AD and advance the field of AD precision medicine., Highlights: APOE is a central player in the pathogenesis of Alzheimer's disease. APOE exerts a numerous effects throughout the brain on amyloid-beta, tau, and other pathways. The AAIC Advancements: APOE conference encouraged discussions and collaborations on understanding the role of APOE., (© 2024 The Author(s). Alzheimer's & Dementia published by Wiley Periodicals LLC on behalf of Alzheimer's Association.)

The maturation of brain microvascular endothelial cells leads to the formation of a tightly sealed monolayer, known as the blood-brain barrier (BBB). The BBB damage is associated with the pathogenesis of age-related neurodegenerative diseases including vascular cognitive impairment and Alzheimer's disease. Growing knowledge in the field of epigenetics can enhance the understanding of molecular profile of the BBB and has great potential for the development of novel therapeutic strategies or targets to repair a disrupted BBB. Histone deacetylases (HDACs) inhibitors are epigenetic regulators that can induce acetylation of histones and induce open chromatin conformation, promoting gene expression by enhancing the binding of DNA with transcription factors. We investigated how HDAC inhibition influences the barrier integrity using immortalized human endothelial cells (HCMEC/D3) and the human induced pluripotent stem cell (iPSC)-derived brain vascular endothelial cells. The endothelial cells were treated with or without a novel compound named W2A-16. W2A-16 not only activates Wnt/β-catenin signaling but also functions as a class I HDAC inhibitor. We demonstrated that the administration with W2A-16 sustained barrier properties of the monolayer of endothelial cells, as evidenced by increased trans-endothelial electrical resistance (TEER). The BBB-related genes and protein expression were also increased compared with non-treated controls. Analysis of transcript profiles through RNA-sequencing in hCMEC/D3 cells indicated that W2A-16 potentially enhances BBB integrity by influencing genes associated with the regulation of the extracellular microenvironment. These findings collectively propose that the HDAC inhibition by W2A-16 plays a facilitating role in the formation of the BBB. Pharmacological approaches to inhibit HDAC may be a potential therapeutic strategy to boost and/or restore BBB integrity., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Inoue, Ren, Zhang, Bamkole, Islam, Selvaraj, Lu, Caulfield, Li and Kanekiyo.)

Introduction: Corticobasal syndrome (CBS) can result from underlying Alzheimer's disease (AD) pathologies. Little is known about the utility of blood plasma metrics to predict positron emission tomography (PET) biomarker-confirmed AD in CBS., Methods: A cohort of eighteen CBS patients (8 amyloid beta [Aβ]+; 10 Aβ-) and 8 cognitively unimpaired (CU) individuals underwent PET imaging and plasma analysis. Plasma concentrations were compared using a Kruskal-Wallis test. Spearman correlations assessed relationships between plasma concentrations and PET uptake., Results: CBS Aβ+ group showed a reduced Aβ42/40 ratio, with elevated phosphorylated tau (p-tau)181, glial fibrillary acidic protein (GFAP), and neurofilament light (NfL) concentrations, while CBS Aβ- group only showed elevated NfL concentration compared to CU. Both p-tau181 and GFAP were able to differentiate CBS Aβ- from CBS Aβ+ and showed positive associations with Aβ and tau PET uptake., Discussion: This study supports use of plasma p-tau181 and GFAP to detect AD in CBS. NfL shows potential as a non-specific disease biomarker of CBS regardless of underlying pathology., Highlights: Plasma phosphorylated tau (p-tau)181 and glial fibrillary acidic protein (GFAP) concentrations differentiate corticobasal syndrome (CBS) amyloid beta (Aβ)- from CBS Aβ+. Plasma neurofilament light concentrations are elevated in CBS Aβ- and Aβ+ compared to controls. Plasma p-tau181 and GFAP concentrations were associated with Aβ and tau positron emission tomography (PET) uptake. Aβ42/40 ratio showed a negative correlation with Aβ PET uptake., (© 2024 The Author(s). Alzheimer's & Dementia published by Wiley Periodicals LLC on behalf of Alzheimer's Association.)

To uncover molecular changes underlying blood-brain-barrier dysfunction in Alzheimer's disease, we performed single nucleus RNA sequencing in 24 Alzheimer's disease and control brains and focused on vascular and astrocyte clusters as main cell types of blood-brain-barrier gliovascular-unit. The majority of the vascular transcriptional changes were in pericytes. Of the vascular molecular targets predicted to interact with astrocytic ligands, SMAD3, upregulated in Alzheimer's disease pericytes, has the highest number of ligands including VEGFA, downregulated in Alzheimer's disease astrocytes. We validated these findings with external datasets comprising 4,730 pericyte and 150,664 astrocyte nuclei. Blood SMAD3 levels are associated with Alzheimer's disease-related neuroimaging outcomes. We determined inverse relationships between pericytic SMAD3 and astrocytic VEGFA in human iPSC and zebrafish models. Here, we detect vast transcriptome changes in Alzheimer's disease at the gliovascular-unit, prioritize perturbed pericytic SMAD3-astrocytic VEGFA interactions, and validate these in cross-species models to provide a molecular mechanism of blood-brain-barrier disintegrity in Alzheimer's disease., (© 2024. The Author(s).)

The immune system substantially influences age-related cognitive decline and Alzheimer's disease (AD) progression, affected by genetic and environmental factors. In a Mayo Clinic Study of Aging cohort, we examined how risk factors like APOE genotype, age, and sex affect inflammatory molecules and AD biomarkers in cerebrospinal fluid (CSF). Among cognitively unimpaired individuals over 65 ( N = 298), we measured 365 CSF inflammatory molecules, finding age, sex, and diabetes status predominantly influencing their levels. We observed age-related correlations with AD biomarkers such as total tau, phosphorylated tau-181, neurofilament light chain (NfL), and YKL40. APOE4 was associated with lower Aβ42 and higher SNAP25 in CSF. We explored baseline variables predicting cognitive decline risk, finding age, CSF Aβ42, NfL, and REG4 to be independently correlated. Subjects with older age, lower Aβ42, higher NfL, and higher REG4 at baseline had increased cognitive impairment risk during follow-up. This suggests that assessing CSF inflammatory molecules and AD biomarkers could predict cognitive impairment risk in the elderly.

ABCA7 loss-of-function variants are associated with increased risk of Alzheimer's disease (AD). Using ABCA7 knockout human iPSC models generated with CRISPR/Cas9, we investigated the impacts of ABCA7 deficiency on neuronal metabolism and function. Lipidomics revealed that mitochondria-related phospholipids, such as phosphatidylglycerol and cardiolipin were reduced in the ABCA7-deficient iPSC-derived cortical organoids. Consistently, ABCA7 deficiency-induced alterations of mitochondrial morphology accompanied by reduced ATP synthase activity and exacerbated oxidative damage in the organoids. Furthermore, ABCA7-deficient iPSC-derived neurons showed compromised mitochondrial respiration and excess ROS generation, as well as enlarged mitochondrial morphology compared to the isogenic controls. ABCA7 deficiency also decreased spontaneous synaptic firing and network formation in iPSC-derived neurons, in which the effects were rescued by supplementation with phosphatidylglycerol or NAD + precursor, nicotinamide mononucleotide. Importantly, effects of ABCA7 deficiency on mitochondria morphology and synapses were recapitulated in synaptosomes isolated from the brain of neuron-specific Abca7 knockout mice. Together, our results provide evidence that ABCA7 loss-of-function contributes to AD risk by modulating mitochondria lipid metabolism., (© 2023. The Author(s).)