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Background: Species-specific differences in astrocytes and their Alzheimer disease-associated pathology may influence cellular responses to other insults. Herein, human glial chimeric mice were generated to evaluate how Alzheimer disease predisposing genetic background in human astrocytes contributes to behavioral outcome and brain pathology after cortical photothrombotic ischemia. Methods: Neonatal (P0) immunodeficient mice of both sexes were transplanted with induced pluripotent stem cell–derived astrocyte progenitors from Alzheimer disease patients carrying PSEN1 exon 9 deletion (PSEN1 ΔE9), with isogenic controls, with cells from a healthy donor, or with mouse astrocytes or vehicle. After 14 months, a photothrombotic lesion was produced with Rose Bengal in the motor cortex. Behavior was assessed before ischemia and 1 and 4 weeks after the induction of stroke, followed by tissue perfusion for histology. Results: Open field, cylinder, and grid-walking tests showed a persistent locomotor and sensorimotor impairment after ischemia and female mice had larger infarct sizes; yet, these were not affected by astrocytes with PSEN1 ΔE9 background. Staining for human nuclear antigen confirmed that human cells successfully engrafted throughout the mouse brain. However, only a small number of human cells were positive for astrocytic marker GFAP (glial fibrillary acidic protein), mostly located in the corpus callosum and retaining complex human-specific morphology with longer processes compared with host counterparts. While host astrocytes formed the glial scar, human astrocytes were scattered in small numbers close to the lesion boundary. Aβ (beta-amyloid) deposits were not present in PSEN1 ΔE9 astrocyte-transplanted mice. Conclusions: Transplanted human cells survived and distributed widely in the host brain but had no impact on severity of ischemic damage after cortical photothrombosis in chimeric mice. Only a small number of transplanted human astrocytes acquired GFAP-positive glial phenotype or migrated toward the ischemic lesion forming glial scar. PSEN1 ΔE9 astrocytes did not impair behavioral recovery after experimental stroke.

2019 coronavirus disease (COVID-19) is a disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In addition to respiratory illness, COVID-19 patients exhibit neurological symptoms lasting from weeks to months (long COVID). It is unclear whether these neurological manifestations are due to an infection of brain cells. We found that a small fraction of human induced pluripotent stem cell (iPSC)-derived neurons, but not astrocytes, were naturally susceptible to SARS-CoV-2. Based on the inhibitory effect of blocking antibodies, the infection seemed to depend on the receptor angiotensin-converting enzyme 2 (ACE2), despite very low levels of its expression in neurons. The presence of double-stranded RNA in the cytoplasm (the hallmark of viral replication), abundant synthesis of viral late genes localized throughout infected cells, and an increase in the level of viral RNA in the culture medium (viral release) within the first 48 h of infection suggested that the infection was productive. Productive entry of SARS-CoV-2 requires the fusion of the viral and cellular membranes, which results in the delivery of the viral genome into the cytoplasm of the target cell. The fusion is triggered by proteolytic cleavage of the viral surface spike protein, which can occur at the plasma membrane or from endosomes or lysosomes. We found that SARS-CoV-2 infection of human neurons was insensitive to nafamostat and camostat, which inhibit cellular serine proteases, including transmembrane serine protease 2 (TMPRSS2). Inhibition of cathepsin L also did not significantly block infection. In contrast, the neuronal infection was blocked by apilimod, an inhibitor of phosphatidyl-inositol 5 kinase (PIK5K), which regulates early to late endosome maturation.IMPORTANCE COVID-19 is a disease caused by the coronavirus SARS-CoV-2. Millions of patients display neurological symptoms, including headache, impairment of memory, seizures, and encephalopathy, as well as anatomical abnormalities, such as changes in brain morphology. SARS-CoV-2 infection of the human brain has been documented, but it is unclear whether the observed neurological symptoms are linked to direct brain infection. The mechanism of virus entry into neurons has also not been characterized. Here, we investigated SARS-CoV-2 infection by using a human iPSC-derived neural cell model and found that a small fraction of cortical-like neurons was naturally susceptible to infection. The productive infection was ACE2 dependent and TMPRSS2 independent. We also found that the virus used the late endosomal and lysosomal pathway for cell entry and that the infection could be blocked by apilimod, an inhibitor of cellular PIK5K.

Schizophrenia is a neuropsychiatric disorder, caused by a combination of genetic and environmental factors. Recently, metabolomic studies based on patients’ biofluids and post-mortem brain specimens have revealed altered levels of distinct metabolites between healthy individuals and patients with schizophrenia (SCZ). However, a putative link between dysregulated metabolites and distorted neurodevelopment has not been assessed and access to patients’ material is restricted. In this study, we aimed to investigate a presumed correlation between transcriptomics and metabolomics in a SCZ model using patient-derived induced pluripotent stem cells (iPSCs). iPSCs were differentiated towards cortical neurons and samples were collected longitudinally at defined developmental stages, such as neuroepithelium, radial glia, young and mature neurons. Samples were subsequently analyzed by bulk RNA-sequencing and targeted metabolomics. The transcriptomic analysis revealed dysregulations in several extracellular matrix-related genes in the SCZ samples observed in early neurogenesis, including members of the collagen superfamily. At the metabolic level, several lipid and amino acid discrepancies were correlated to the SCZ phenotype. By employing a novel in silico analysis, we correlated the transcriptome with the metabolome through the generation of integrative networks. The network comparison between SCZ and healthy controls revealed a number of consistently affected pathways in SCZ, related to early stages of cortical development, indicating abnormalities in membrane composition, lipid homeostasis and amino acid imbalances. Ultimately, our study suggests a novel approach of correlating in vitro metabolic and transcriptomic data obtained from a patient-derived iPSC model. This type of analysis will offer novel insights in cellular and genetic mechanisms underlying the pathogenesis of complex neuropsychiatric disorders, such as schizophrenia.

COVID-19 is a disease caused by coronavirus SARS-CoV-2. In addition to respiratory illness, COVID-19 patients exhibit neurological symptoms that can last from weeks to months (long COVID). It is unclear whether these neurological manifestations are due to infection of brain cells. We found that a small fraction of cortical neurons, but not astrocytes, were naturally susceptible to SARS-CoV-2. Based on the inhibitory effect of blocking antibodies, the infection seemed to depend on the receptor angiotensin-converting enzyme 2 (ACE2), which was expressed at very low levels. Although only a limited number of neurons was infectable, the infection was productive, as demonstrated by the presence of double-stranded RNA in the cytoplasm (the hallmark of viral replication), abundant synthesis of viral late genes localized throughout the neuronal cell, and an increase in viral RNA in the culture medium within the first 48 h of infection (viral release). The productive entry of SARS-CoV-2 requires the fusion of the viral and cellular membranes, which results in the delivery of viral genome into the cytoplasm of the target cell. The fusion is triggered by proteolytic cleavage of the viral surface protein spike, which can occur at the plasma membrane or from endo/lysosomes. Using specific combinations of small-molecule inhibitors, we found that SARS-CoV-2 infection of human neurons was insensitive to nafamostat and camostat, which inhibit cellular serine proteases found on the cell surface, including TMPRSS2. In contrast, the infection was blocked by apilimod, an inhibitor of phosphatidyl-inositol 5 kinase (PIK5K) that regulates endosomal maturation.ImportanceCOVID-19 is a disease caused by coronavirus SARS-CoV-2. Millions of patients display neurological symptoms, including headache, impairment of memory, seizures and encephalopathy, as well as anatomical abnormalities such as changes in brain morphology. Whether these symptoms are linked to brain infection is not clear. The mechanism of the virus entry into neurons has also not been characterized. Here we investigated SARS-CoV-2 infection using a human iPSC-derived neural cell model and found that a small fraction of cortical neurons was naturally susceptible to infection. The infection depended on the ACE2 receptor and was productive. We also found that the virus used the late endosomal/lysosomal pathway for cell entry and that the infection could be blocked by apilimod, an inhibitor of the cellular phosphatidyl-inositol 5 kinase.

BackgroundMicroglia are the endogenous immune cells of the brain and act as sensors of pathology to maintain brain homeostasis and eliminate potential threats. In Alzheimer’s disease (AD), toxic amyloid beta (Aβ) accumulates in the brain and forms stiff plaques. In late-onset AD accounting for 95% of all cases, this is thought to be due to reduced clearance of Aβ. Human genome-wide association studies and animal models suggest that reduced clearance results from aberrant function of microglia. While the impact of neurochemical pathways on microglia have been broadly studied, mechanical receptors regulating microglial functions remain largely unexplored.MethodsHere we showed that a mechanotransduction ion channel, PIEZO1, is expressed and functional in human and mouse microglia. We used a small molecule agonist, Yoda1, to study how activation of PIEZO1 affects AD-related functions in human induced pluripotent stem cell (iPSC) -derived microglia-like cells (iMGL) under controlled laboratory experiments. Cell survival, metabolism, phagocytosis and lysosomal activity were assessed using real-time functional assays. To evaluate the effect of activation of PIEZO1 in vivo, 5-month-old 5xFAD male mice were infused daily with Yoda1 for two weeks through intracranial cannulas. Microglial Iba1 expression and Aβ pathology were quantified with immunohistochemistry and confocal microscopy. Published human and mouse AD datasets were used for in-depth analysis of PIEZO1 gene expression and related pathways in microglial subpopulations.ResultsWe show that PIEZO1 orchestrates Aβ clearance by enhancing microglial survival, phagocytosis, and lysosomal activity. Aβ inhibited PIEZO1-mediated calcium transients, whereas activation of PIEZO1 with a selective agonist, Yoda1, improved microglial phagocytosis resulting in Aβ clearance both in human and mouse models of AD. Moreover, PIEZO1 expression was associated with a unique microglial transcriptional phenotype in AD as indicated by assessment of cellular metabolism, and human and mouse single cell datasets.ConclusionThese results indicate that the compromised function of microglia in AD could be improved by controlled activation of PIEZO1 channels resulting in alleviated Aβ burden. Pharmacological regulation of these mechanoreceptors in microglia could represent a novel therapeutic paradigm for AD.GRAPHICAL ABSTRACT

Summary Multiple protocols have been published for generation of iMGLs from hESCs/iPSCs. To date, there are no guides to assist researchers to determine the most appropriate methodology for microglial studies. To establish a framework to facilitate future microglial studies, we first performed a comparative transcriptional analysis between iMGLs derived using three published datasets, which allowed us to establish the baseline protocol that is most representative of bona fide human microglia. Secondly, using CRISPR to tag the classic microglial marker CX3CR1 with nanoluciferase and tdTomato, we generated and functionally validated a reporter ESC line. Finally, using this cell line, we demonstrated that co-culture of iMGL precursors with human glia and neurons enhanced transcriptional resemblance of iMGLs to ex vivo microglia. Together, our comprehensive molecular analysis and reporter cell line are a useful resource for neurobiologists seeking to use iMGLs for disease modeling and drug screening studies., Highlights • Integrated molecular characterization reveals differences in four iMGL protocols • A dual tdTomato and nanoluciferase reporter tool was generated to track iMGLs via CX3CR1 • Kinetics of surface marker expression during iMGL differentiation • Co-culture with glia/neurons restores ex vivo microglial transcription factors, In this article, Jose Polo and colleagues molecularly compare existing microglia differentiation methods from stem cells, generate a new dual fluorescent and enzymatic reporter tool to study microglia, and show that human glia/neuron co-culture pushes the regulatory landscape of in vitro microglia-like cells to more closely resemble bona fide microglia.

Human cerebral organoids, derived from induced pluripotent stem cells, offer a unique in vitro research window to the development of the cerebral cortex. However, a key player in the developing brain, the microglia, do not natively emerge in cerebral organoids. Here we show that erythromyeloid progenitors (EMPs), differentiated from induced pluripotent stem cells, migrate to cerebral organoids, and mature into microglia-like cells and interact with synaptic material. Patch-clamp electrophysiological recordings show that the microglia-like population supported the emergence of more mature and diversified neuronal phenotypes displaying repetitive firing of action potentials, low-threshold spikes and synaptic activity, while multielectrode array recordings revealed spontaneous bursting activity and increased power of gamma-band oscillations upon pharmacological challenge with NMDA. To conclude, microglia-like cells within the organoids promote neuronal and network maturation and recapitulate some aspects of microglia-neuron co-development in vivo, indicating that cerebral organoids could be a useful biorealistic human in vitro platform for studying microglia-neuron interactions.

Previous studies have implicated several brain cell types in schizophrenia (SCZ), but the genetic impact of astrocytes is unknown. Considering their high complexity in humans, astrocytes are likely key determinants of neurodevelopmental diseases, such as SCZ. Human induced pluripotent stem cell (hiPSC)-derived astrocytes differentiated from five monozygotic twin pairs discordant for SCZ and five healthy subjects were studied for alterations related to high genetic risk and clinical manifestation of SCZ in astrocyte transcriptomics, neuron-astrocyte co-cultures, and in humanized mice. We found gene expression and signaling pathway alterations related to synaptic dysfunction, inflammation, and extracellular matrix components in SCZ astrocytes, and demyelination in SCZ astrocyte transplanted mice. While Ingenuity Pathway Analysis identified SCZ disease and synaptic transmission pathway changes in SCZ astrocytes, the most consistent findings were related to collagen and cell adhesion associated pathways. Neuronal responses to glutamate and GABA differed between astrocytes from control persons, affected twins, and their unaffected co-twins and were normalized by clozapine treatment. SCZ astrocyte cell transplantation to the mouse forebrain caused gene expression changes in synaptic dysfunction and inflammation pathways of mouse brain cells and resulted in behavioral changes in cognitive and olfactory functions. Differentially expressed transcriptomes and signaling pathways related to synaptic functions, inflammation, and especially collagen and glycoprotein 6 pathways indicate abnormal extracellular matrix composition in the brain as one of the key characteristics in the etiology of SCZ.

Over a decade of schizophrenia research using human induced pluripotent stem cell (iPSC)-derived neural models has provided substantial data describing neurobiological characteristics of the disorder in vitro. Simultaneously, translation of the results into general mechanistic concepts underlying schizophrenia pathophysiology has been trailing behind. Given that modeling brain function using cell cultures is challenging, the gap between the in vitro models and schizophrenia as a clinical disorder has remained wide. In this review, we highlight reproducible findings and emerging trends in recent schizophrenia-related iPSC studies. We illuminate the relevance of the results in the context of human brain development, with a focus on processes coinciding with critical developmental periods for schizophrenia.

The molecular pathophysiological mechanisms underlying schizophrenia have remained unknown, and no treatment exists for primary prevention. We used Ingenuity Pathway Analysis to analyze canonical and causal pathways in two different datasets, including patients from Finland and USA. The most significant findings in canonical pathway analysis were observed for glutamate receptor signaling, hepatic fibrosis, and glycoprotein 6 (GP6) pathways in the Finnish dataset, and GP6 and hepatic fibrosis pathways in the US dataset. In data-driven causal pathways, ADCYAP1, ADAMTS. and CACNA genes were involved in the majority of the top 10 pathways differentiating patients and controls in both Finnish and US datasets. Results from a Finnish nation-wide database showed that the risk of schizophrenia relapse was 41% lower among first-episode patients during the use of losartan, the master regulator of an ADCYAP1, ADAM'S, and CACNA -related pathway, compared to those time periods when the same individual did not use the drug. The results from the two independent datasets suggest that the GP6 signaling pathway, and the ADCYAPI, ADAATTS, and CACNA-related purine, oxidative stress, and glutamatergic signaling pathways are among primary pathophysiological alterations in schizophrenia among patients with European ancestry. While no reproducible dopaminergic alterations were observed, the results imply that agents such as losartan, and ADCYAP1/PACAP -deficit alleviators, such as metabotropic glutamate 2/3 agonise MGS0028 and 5-HT7 antagonists-which have shown beneficial effects in an experimental Adcyapl(-/-) mouse model for schizophrenia - could be potential treatments even before the full manifestation of illness involving dopaminergic abnormalities. (C) 2021 The Authors. Published by Elsevier B.V.

Induced pluripotent stem cells (iPSCs) are a self-renewable pool of cells derived from an organism’s somatic cells. These can then be programmed to other cell types, including neurons. Use of iPSCs in research has been two-fold as they have been used for human disease modelling as well as for the possibility to generate new therapies. Particularly in complex human diseases, such as neurodegenerative diseases, iPSCs can give advantages over traditional animal models in that they more accurately represent the human genome. Additionally, patient-derived cells can be modified using gene editing technology and further transplanted to the brain. Glial cells have recently become important avenues of research in the field of neurodegenerative diseases, for example, in Alzheimer’s disease and Parkinson’s disease. This review focuses on using glial cells (astrocytes, microglia, and oligodendrocytes) derived from human iPSCs in order to give a better understanding of how these cells contribute to neurodegenerative disease pathology. Using glia iPSCs in in vitro cell culture, cerebral organoids, and intracranial transplantation may give us future insight into both more accurate models and disease-modifying therapies.

Psychopathy is an extreme form of antisocial behavior, with about 1% prevalence in the general population, and 10–30% among incarcerated criminal offenders. Although the heritability of severe antisocial behavior is up to 50%, the genetic background is unclear. The underlying molecular mechanisms have remained unknown but several previous studies suggest that abnormal glucose metabolism and opioidergic neurotransmission contribute to violent offending and psychopathy. Here we show using iPSC-derived cortical neurons and astrocytes from six incarcerated extremely antisocial and violent offenders, three nonpsychopathic individuals with substance abuse, and six healthy controls that there are robust alterations in the expression of several genes and immune response-related molecular pathways which were specific for psychopathy. In neurons, psychopathy was associated with marked upregulation of RPL10P9 and ZNF132, and downregulation of CDH5 and OPRD1. In astrocytes, RPL10P9 and MT-RNR2 were upregulated. Expression of aforementioned genes explained 30–92% of the variance of psychopathic symptoms. The gene expression findings were confirmed with qPCR. These genes may be relevant to the lack of empathy and emotional callousness seen in psychopathy, since several studies have linked these genes to autism and social interaction.

Astrocytes are the most abundant cell type in the brain. They were long considered only as passive support for neuronal cells. However, recent data have revealed many active roles for these cells both in maintenance of the normal physiological homeostasis in the brain as well as in neurodegeneration and disease. Moreover, human astrocytes have been found to be much more complex than their rodent counterparts, and to date, astrocytes are known to actively participate in a multitude of processes such as neurotransmitter uptake and recycling, gliotransmitter release, neuroenergetics, inflammation, modulation of synaptic activity, ionic balance, maintenance of the blood–brain barrier, and many other crucial functions of the brain. This review focuses on the role of astrocytes in human neurodegenerative disease and the potential of the novel stem cell-based platforms in modeling astrocytic functions in health and in disease.

The research on neurodegenerative disorders has long focused on neuronal pathology and used transgenic mice as disease models. However, our understanding of the chronic neurodegenerative process in the human brain is still very limited. It is increasingly recognized that neuronal loss is not caused solely by intrinsic degenerative processes but rather via impaired interactions with surrounding glia and other brain cells. Dysfunctional astrocytes do not provide sufficient nutrients and antioxidants to the neurons, while dysfunctional microglia cannot efficiently clear pathogens and cell debris from extracellular space, thus resulting in chronic inflammatory processes in the brain. Importantly, human glia, especially the astrocytes, differ significantly in morphology and function from their mouse counterparts, and therefore more human-based disease models are needed. Recent advances in stem cell technology make it possible to reprogram human patients' somatic cells to induced pluripotent stem cells (iPSC) and differentiate them further into patient-specific glia and neurons, thus providing a virtually unlimited source of human brain cells. This review summarizes the recent studies using iPSC-derived glial models of Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis and discusses the applicability of these models to drug testing. This line of research has shown that targeting glial metabolism can improve the survival and function of cocultured neurons and thus provide a basis for future neuroprotective treatments.

Lipid peroxidation-initiated ferroptosis is an iron-dependent mechanism of programmed cell death taking place in neurological diseases. Here we show that a condensed benzo[b]thiazine derivative small molecule with an arylthiazine backbone (ADA-409-052) inhibits tert-Butyl hydroperoxide (TBHP)-induced lipid peroxidation (LP) and protects against ferroptotic cell death triggered by glutathione (GSH) depletion or glutathione peroxidase 4 (GPx4) inhibition in neuronal cell lines. In addition, ADA-409-052 suppresses pro-inflammatory activation of BV2 microglia and protects N2a neuronal cells from cell death induced by pro-inflammatory RAW 264.7 macrophages. Moreover, ADA-409-052 efficiently reduces infarct volume, edema and expression of pro-inflammatory genes in a mouse model of thromboembolic stroke. Targeting ferroptosis may be a promising therapeutic strategy in neurological diseases involving severe neuronal death and neuroinflammation.

Parkinson’s disease (PD) affects one to two individuals per thousands, making it the most common neurodegenerative disorder affecting movement. PD prevalence increases with age, and men are more likely (1.5x) to be afflicted. Currently, there is no cure for PD and no satisfactory therapeutics are available that can slow the progressive loss of dopaminergic neurons or prevent Lewy body formation. Loss of dopamine-producing neurons in PD is often accompanied by an inflammatory response in surrounding glial cells, microglia, and astrocytes. Glial cells, and in particular microglia, represent the first line of defense in the brain and react to pathological events through a cascade of inflammatory processes. In turn, astrocytes, in their reactive state, modulate positively or negatively the progression of multiple neurological disorders, including PD. Glial cells express PD-associated genes and mutations in these genes may alter their function, thereby contributing to the onset and progression of neuronal degeneration through non–cell-autonomous mechanisms. Because of difficulties in accessing patient brain tissue, the majority of glia research in the PD field has been obtained from postmortem brains or animal studies. Recent advances in stem cell technology make it possible to reprogram patients’ somatic cells to induced pluripotent stem cells (iPSCs) and to differentiate these further into disease-relevant cell types. Here, we summarize recent progress in the studies on the non–cell-autonomous mechanisms in PD. We review the potential of novel stem cell–based platforms in modeling PD pathology as well as address the key challenges of using stem cell technology. Finally, we highlight future directions for the use of iPSC-derived brain cells in PD research.

Human stem cell-derived brain organoids provide a physiologically relevant in vitro 3D brain model for studies of neurological development that are unique to the human nervous system. Prior studies have reported protocols that support the maturation of microglia from mesodermal progenitors leading to innately developing microglia within the organoids. However, although microglia are known to support neuronal development in rodents, none of the previous studies have reported what is the impact of microglia on neuronal growth and maturation in human brain organoids. Here we show that incorporating microglial progenitors into the developing organoid supports neuronal maturation, the emergence of neurons capable of firing repetitive action potentials and the appearance of synaptic and neuronal bursting activity. Immunocompetent organoids enable experimental strategies for interrogating fundamental questions on microglial and neuronal diversity and function during human brain development.

Human stem cell-derived brain organoids provide a physiologically relevant in vitro 3D brain model for studies of neurological development that are unique to the human nervous system. Prior studies have reported protocols that support the maturation of microglia from mesodermal progenitors leading to innately developing microglia within the organoids. However, although microglia are known to support neuronal development in rodents, none of the previous studies have reported what is the impact of microglia on neuronal growth and maturation in human brain organoids. Here we show that incorporating microglial progenitors into the developing organoid supports neuronal maturation, the emergence of neurons capable of firing repetitive action potentials and the appearance of synaptic and neuronal bursting activity. Immunocompetent organoids enable experimental strategies for interrogating fundamental questions on microglial and neuronal diversity and function during human brain development.

Human astrocytes are multifunctional brain cells and may contribute to the pathophysiology of schizophrenia (SCZ). We differentiated astrocytes from induced pluripotent stem cells of monozygotic twins discordant for SCZ, and found sex-specific gene expression and signaling pathway alterations related particularly to inflammation and synaptic functions. While Ingenuity Pathway Analysis identified SCZ disease and synaptic transmission pathway changes in SCZ astrocytes, the most consistent findings were related to collagen and cell adhesion associated pathways. Neuronal responses to glutamate and GABA differed between astrocytes from control persons, affected twins, and their unaffected co-twins, and were normalized by clozapine treatment. SCZ astrocyte cell transplantation to the mouse forebrain caused gene expression changes in demyelination, synaptic dysfunction and inflammation pathways of mouse brain cells and resulted in behavioral changes in cognitive and olfactory functions. Altogether, our results show that astrocytes contribute to both familial risk and clinical manifestation of SCZ in a sex-specific manner.

The molecular pathophysiological mechanisms underlying schizophrenia have remained unknown, and no treatment exists for primary prevention. Studies using stem cell-derived neurons have investigated differentially expressed genes (DEGs) and GO and KEGG pathways between patients and controls, but not analyzed data-driven causal molecular pathways involved. We used Ingenuity Pathway Analysis (IPA) to analyze canonical and causal pathways in two different datasets, including patients from Finland and USA. The most significant findings in canonical pathway analysis were observed for glutamate receptor signaling, hepatic fibrosis, and glycoprotein 6 (GP6) pathways in the Finnish dataset, and GP6 and hepatic fibrosis pathways in the US dataset. In data-driven causal pathways, ADCYAP1, ADAMTS, and CACNA genes were involved in the majority of the top 10 pathways differentiating patients and controls in both Finnish and US datasets. In contrast, no dopamine-specific genes were consistently involved. Results from a Finnish nation-wide database showed that the risk of schizophrenia relapse was 41% lower among first-episode patients during the use of losartan, the master regulator of an ADCYAP1, ADAMTS, and CACNA -related pathway, compared to those time periods when the same individual did not use the drug. This association was not attributable to general adherence to drug treatments. The results from the two independent datasets suggest that the GP6 signaling pathway, and the ADCYAP1, ADAMTS, and CACNA -related purine, oxidative stress, and glutamatergic signaling pathways are primary pathophysiological alterations in schizophrenia among patients with European ancestry. While no reproducible dopaminergic alterations were observed, the results imply that agents such as losartan, and ADCYAP1/PACAP -deficit alleviators, such as metabotropic glutamate 2/3 agonist MGS0028 and 5-HT7 antagonists – which have shown beneficial effects in an experimental Adcyap1-/- mouse model for schizophrenia – could be potential treatments before the full manifestation of illness involving dopaminergic abnormalities.

A double mutation (KM670/671NL) in amyloid precursor protein gene (APP) is causative for familial Alzheimer's disease and has been shown to increase the total Aβ burden. Here we report the generation and characterization of an iPSC line from a fAD patient carrying APP KM670/671NL. The generated iPSCs retained the mutation, expressed pluripotency markers, showed a normal karyotype and differentiated into all three germ layers. This iPSC line can be used, for example, in disease modeling and mechanistic studies.Resource table.Unlabelled TableUnique stem cell line identifierUEFi002-AAlternative name(s) of stem cell lineLL008 1.4InstitutionA.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, FinlandContact information of distributorProf. Jari Koistinaho(jari.koistinaho@uef.fi; jari.koistinaho@helsinki.fi)Type of cell lineiPSCOriginHumanAdditional origin infoAge: 58Sex: FemaleEthnicity: ScandinavianCell SourceSkin fibroblastsClonalityClonalMethod of reprogrammingSendai virus carrying OCT3/4, SOX2, KLF4 and c-MYC(CytoTune 1.0)Genetic ModificationNoType of ModificationN/AAssociated diseaseFamilial Alzheimer's diseaseGene/locusAPP (MIM # 104760) located on the long arm of chromosome 21 at position 21q21.3; 27,269,939 G > T, 27269938 A > C (rs63751263, rs63750445)Method of modificationN/AName of transgene or resistanceN/AInducible/constitutive systemN/ADate archived/stock dateMarch 2016Cell line repository/bankN/AEthical approvalEthical license number 2017/834–31/1 (The ethical review board of Karolinska Institutet/Karolinska University Hospital)

It has remained unclear why schizophrenia typically manifests after adolescence and which neurobiological mechanisms are underlying the cascade leading to the actual onset of the illness. Here we show that the use of induced pluripotent stem cell-derived neurons of monozygotic twins from pairs discordant for schizophrenia enhances disease-specific signal by minimizing genetic heterogeneity. In proteomic and pathway analyses, clinical illness is associated especially with altered glycosaminoglycan, GABAergic synapse, sialylation, and purine metabolism pathways. Although only 12% of all 19,462 genes are expressed differentially between healthy males and females, up to 61% of the illness-related genes are sex specific. These results on sex-specific genes are replicated in another dataset. This implies that the pathophysiology differs between males and females, and may explain why symptoms appear after adolescence when the expression of many sex-specific genes change, and suggests the need for sex-specific treatments. Noise due to genetic heterogeneity potentially impacts the the discovery of genes that contribute to diseases such as schizophrenia (SCZ). In this study, authors minimize the disease-irrelevant noise between SCZ and healthy individuals by profiling transcriptional signatures among discordant monozygotic twin pairs, and demonstrate that although sexes share many of the final common pathways, the underlying primary pathophysiology of SCZ differs between males and females.

Summary The blood-brain barrier (BBB) presents a barrier for circulating factors, but simultaneously challenges drug delivery. How the BBB is altered in Alzheimer disease (AD) is not fully understood. To facilitate this analysis, we derived brain endothelial cells (iBECs) from human induced pluripotent stem cells (hiPSCs) of several patients carrying the familial AD PSEN1 mutation. We demonstrate that, compared with isogenic PSEN1 corrected and control iBECs, AD-iBECs exhibit altered tight and adherens junction protein expression as well as efflux properties. Furthermore, by applying focused ultrasound (FUS) that transiently opens the BBB and achieves multiple therapeutic effects in AD mouse models, we found an altered permeability to 3–5 kDa dextran as a model cargo and the amyloid-β (Aβ) peptide in AD-iBECs compared with control iBECs. This presents human-derived in vitro models of the BBB as a valuable tool to understand its role and properties in a disease context, with possible implications for drug delivery., Highlights • iBECs with familial AD mutation express altered levels of tight junction proteins • AD-iBECs exhibit altered efflux transporter expression and function to control iBECs • Focused ultrasound disrupts iBEC monolayer indicating effects of BBB opening • AD-iBECs respond differently to control iBECs to effects of focused ultrasound, In this article, Oikari and colleagues use patient-derived iPSCs with a familial Alzheimer disease (AD) mutation to study the phenotypical and functional differences of brain endothelial cells (iBECs) in AD. In addition, the authors study the effects of focused ultrasound on the iBEC monolayer to model blood-brain barrier opening and demonstrate key differences between AD and control iBECs.

BACKGROUND: The estimated heritability of schizophrenia is 80–85%, and if one of monozygotic twins has the illness, the risk for the other twin is about 50%. It has remained unclear which factors are associated just with the increased risk, and which neurobiological mechanisms are related to the cascade leading to actual onset of illness. It has also remained a mystery why this neurodevelopmental disorder manifests itself after adolescence. METHODS: We used iPSC-derived neurons from 5 monozygotic twin pairs discordant for schizophrenia (3 female and 2 male pairs; all 5 affected individuals were chronically symptomatic and treated with antipsychotics, 3 with clozapine) and 6 healthy controls matched by age and sex to enhance signal by minimizing genetic heterogeneity. Diagnoses were assigned using DSM-IV criteria and SCID-I interviews, and severity of symptoms was assessed with PANSS. Skin biopsy-derived fibroblasts were reprogrammed into integration-free induced pluripotent stem cell (iPSCs) lines by Sendai virus technology. The cells were further differentiated into cortical-like neurons expressing markers of GABAergic and glutamatergic neurons. The top genes from RNAseq analysis were validated by quantitative polymerase chain reaction (qPCR). In the proteomic analysis, the 16 samples were processed through the SysQuant workflow using Tandem Mass Tag (TMT) reagents within two TMT 10plexes. A reference pool containing all samples was also included. To identify statistically significant regulated features (peptide, phosphopeptides or proteins), a LIMMA-based modified t-test was performed at the peptide, phosphopeptide and protein levels in pairwise comparisons using distribution-dependent fold change (FC) and p-value (p) thresholds. RESULTS: Transcriptomic and proteomic analyses showed very large effect sizes (differences up to 7.3-fold in gene expression and 2.7-fold in protein levels in the comparison between affected twin versus healthy twin). Among the most robust findings related to disease status were down-regulation of COL6A3, SSTR2, and LHX1 genes, and altered glycosaminoglycan, CAMK2G-related AMPA/NMDA/glutamate, GABAergic synapse, and purine metabolism pathways. While only 12% of genes were differentially expressed between healthy males and females, up to 61% of the illness-related genes were sex-specific (p-values down to 2.3 x 10E-295 for the difference). Most of the genes with the largest effect sizes were different between males and females. At gestational age of 90 days, neurons of affected twins showed altered calcium responses for NMDA-specific glutamate (p < 0.001) and for GABA exposure compared with their healthy twins, and these alterations were normalized when the neurons were treated with clozapine. DISCUSSION: Results imply that somatostatin 2 receptor defect may contribute to dysfunction of NMDA receptors in somatostatin/calreticulin GABAergic interneurons, and that clozapine might have a beneficial effect on this cascade. Consistent findings on down-regulation of N-glygan and calnexin/calreticulin pathways, affecting protein folding in endoplastic reticulum, indicate also their major role in schizophrenia. Our results imply that although both sexes share many of the final common pathways involving the same proteins, the underlying primary pathophysiology of schizophrenia may differ between males and females. This may explain why the disease typically manifests after adolescence, when the expression levels of many sex-specific genes change.

Cerebral stroke induces massive Th1-shifted inflammation both in the brain and the periphery, contributing to the outcome of stroke. A Th1-type response is neurotoxic whereas a Th2-type response is accompanied by secretion of anti-inflammatory cytokines, such as interleukin-4 (IL-4). Interleukin-33 (IL-33) is a cytokine known to induce a shift towards the Th2-type immune response, polarize macrophages/microglia towards the M2-type, and induce production of anti-inflammatory cytokines. We found that the plasma levels of the inhibitory IL-33 receptor, sST2, are increased in human stroke and correlate with a worsened stroke outcome, suggesting an insufficient IL-33-driven Th2-type response. In mouse, peripheral administration of IL-33 reduced stroke-induced cell death and improved the sensitivity of the contralateral front paw at 5days post injury. The IL-33-treated mice had increased levels of IL-4 in the spleen and in the peri-ischemic area of the cortex. Neutralization of IL-4 by administration of an IL-4 antibody partially prevented the IL-33-mediated protection. IL-33 treatment also reduced astrocytic activation in the peri-ischemic area and increased the number of Arginase-1 immunopositive microglia/macrophages at the lesion site. In human T-cells, IL-33 treatment induced IL-4 secretion, and the conditioned media from IL-33-exposed T-cells reduced astrocytic activation. This study demonstrates that IL-33 is protective against ischemic insult by induction of IL-4 secretion and may represent a novel therapeutic approach for the treatment of stroke.