Biology subjects

Levison, S. W.

Publications and source records attributed to Levison, S. W..

9 recordsLinked to original sources

bioRxiv2026

Modeling Prenatal Immune Activation in Human Brain Organoids Uncovers IL-6-Dependent Interneuron Dysmaturation

Prenatal inflammation has been associated with an increased likelihood of the child developing neurodevelopmental conditions, such as autism spectrum disorder (ASD). Several pro-inflammatory cytokines are significantly upregulated and play critical roles during immune activation, with interleukin-6 (IL-6) being particularly prominent. However, the specific impact of elevated IL-6 levels on human neural development remains to be elucidated. To address this, we established a human pluripotent stem cell-based forebrain organoid model enriched for multiple interneuron lineages, validated through immunohistochemistry and transcriptomic alignment with human fetal reference datasets. We showed IL-6 responsiveness via the activation of the JAK/STAT pathway and characterized downstream effects using bulk and single-nucleus RNA sequencing (RNA-seq). Bulk RNA-seq at the end of IL-6 exposure uncovered activation of inflammatory pathways, upregulation of MHC-I machinery, and early disruption of GABAergic signaling programs. Notably, single-nucleus RNA-sequencing performed one month after IL-6 withdrawal revealed a persistent inflammatory transcriptional signature across interneuron development, accompanied by accelerated progression through maturation stages and altered interneuron subtype output. Together, these findings demonstrate that transient prenatal IL-6 exposure is sufficient to reshape human interneuron fate specification and maturation trajectories, providing mechanistic insights into neuroimmune contributions to ASD.

neuroscience↗

bioRxiv2025

Transcriptional profiling defines unique subtypes of transit amplifying neural progenitors within the neonatal mouse subventricular zone

While significant progress has been made in understanding the heterogeneity of Neural Stem Cells (NSCs), our understanding of similar heterogeneity among the more abundant transit amplifying progenitors is lagging. Our work on the neural progenitors (NPs) of the neonatal subventricular zone (SVZ) began over a decade ago, when we used antibodies to the 4 antigens, CD133, LeX, CD140a, and NG2 to perform FACS to classify subsets of the neonatal SVZ as either multi-potential (MP1, MP2, MP3, MP4 and PFMPs), glial-restricted (GRP1, GRP2, and GRP3) or neuron-astrocyte restricted (BNAP). Using RNASeq, we have characterized the distinctive molecular fingerprints of 4 SVZ neural progenitors and compared their gene expression profiles to those of the NSCs. We performed bioinformatic analyses to provide insights into each NP types unique interactome and the transcription factors regulating their development. Overall, we identified 1581 genes upregulated in at least one NP compared to the NSCs. Of these genes, 796 genes were upregulated in BNAP/GRP1 compared to NSCs; 653 in GRP2/MP3; 440 in GRP3; and 527 in PFMPs. One gene that emerged from our analysis that can be used to distinguish the NPs from the NSCs is Etv1, also known as Er81. Also notable is that the neural stem cells downregulated cilia formation genes as they differentiated to become multipotential progenitors. Among the NPs, both PFMP and GRP3 subtypes differentially expressed genes related to neuron and oligodendrocyte development, including Matn4, Lhfpl3 and Olig2. GRP3s uniquely expressed Etv5, a transcription factor known to promote glial cell fate specification, while PFMPs uniquely expressed Lhx6, a transcription factor that regulates interneuron specification. PFMPs also expressed transcripts for olfactory receptors. Unlike the other NPs, the GRP1 and GRP2 NPs upregulated expression of genes for proteins involved in immune function. The present work will serve as an important resource for investigators interested in further defining the transit amplifying progenitors of the mammalian SVZ.

neuroscience↗

bioRxiv2025

Leukemia Inhibitory Factor as a late-stage treatment for delayed white matter loss in concussive head injury

Leukemia Inhibitory Factor (LIF) is an injury-induced cytokine that peaks 48 hours after a traumatic brain injury (TBI). Juvenile LIF haplodeficient mice exhibit desynchronized glial responses, increased neurodegeneration, decreased axonal conductivity and behavioral deficits after a concussive head injury. Given the necessity of LIF during the acute recovery phase after injury, we hypothesized that intranasal LIF (IN-LIF) treatment would prevent neurodegeneration when administered during the chronic recovery period from a mild TBI (mTBI). Young adult male CD1 mice were subjected to a midline, closed-head frontal cortex injury using a flat metal impactor with a 3mm tip to induce a mTBI. In the 6-8 weeks post-mTBI, known to precede axonal atrophy in this mTBI model, two doses of 40 ng and 100 ng of LIF were administered twice daily, 5 days/week for two consecutive weeks. Sensorimotor functions were assessed at 4 and 8 weeks post mTBI, followed by ex-vivo brain magnetic resonance imaging at 9.4T and histopathology. mTBI mice showed sensorimotor deficits at 4 weeks, which worsened by 8 weeks post-injury. IN-LIF treatment prevented the progressive sensorimotor loss seen in the vehicle-treated controls. Increased mean diffusivity and decreased fractional anisotropy were observed in the corpus callosum and prefrontal cortex of mTBI brains. In a dose-dependent manner, IN-LIF prevented the mTBI-induced mean diffusivity increase and fractional anisotropy decrease. Histologically, there was significantly less astrogliosis, microgliosis and axonal injury in the IN-LIF treated mice vs. controls. These results support the therapeutic potential of IN-LIF to reduce delayed neurodegeneration and improve neurological outcomes after mTBIs.

neuroscience↗

bioRxiv2021

Perinatal Inflammation Disturbs Secondary Germinal Zone Neurogenesis and Gliogenesis Producing Deficits in Sociability

Epidemiologic studies have demonstrated that infections during pregnancy increase the risk of offspring developing Schizophrenia, Autism, Depression and Bipolar Disorder and have implicated interleukin-6 (IL-6) as a causal agent. However, other cytokines have been associated with psychiatric disorders; therefore, it remains to be established whether elevating IL-6 is sufficient to alter the trajectory of neural development. Furthermore, most rodent studies have manipulated the maternal immune system at mid-gestation, which affects the stem cells and progenitors in both the primary and secondary germinal matrices. Therefore, a question that remains to be addressed is whether elevating IL-6 when the secondary germinal matrices are most active will affect brain development. Here, we have increased IL-6 from postnatal days 3-6, when the secondary germinal matrices are rapidly expanding. Using Nestin-CreERT2 fate mapping we show that this transient increase in IL-6 decreased neurogenesis in the dentate gyrus of the dorsal hippocampus, reduced astrogliogenesis in the prefrontal cortex and amygdala and decreased oligodendrogenesis in the body and splenium of the corpus callosum all by [~]50%. Moreover, the IL-6 treatment elicited behavioral changes classically associated with neurodevelopmental disorders. As adults, IL-6 injected male mice lost social preference in the social approach test, spent [~]30% less time socially engaging with sexually receptive females and produced [~]50% fewer ultrasonic vocalizations during mating. They also engaged [~]50% more time in self-grooming behavior and had an increase in inhibitory avoidance. Altogether, these data provide new insights into the biological mechanisms linking perinatal immune activation to complex neurodevelopmental brain disorders. Significance statementIn these studies, we doubled circulating IL-6 levels in mice from postnatal days 3-6 to test the hypothesis that this would be sufficient to disturb neural development. More specifically, we hypothesized that IL-6 would affect postnatal neural stem cell and progenitor expansion and specification. We show that this transient increase in IL-6 decreases the numbers of granule neurons in the dorsal hippocampus, astrocytes in the prefrontal cortex and amygdala and oligodendrocytes in the corpus callosum. Importantly, this transient increase in IL-6 changes the sociability, communication and repetitive behaviors of the treated mice as adults, which are core symptoms pertinent to several neurodevelopmental psychiatric disorders.

neuroscience↗

bioRxiv2021

Hyperoxia Inhibits the Growth of Mouse Forebrain Oligodendrocyte Progenitors

NG2 chondroitin sulfate proteoglycan positive oligodendrocyte progenitor cells (OPCs) reside throughout the brain. They divide asymmetrically and differentiate into myelinating oligodendrocytes throughout adulthood. OPCs have been successfully isolated from rodents using several techniques including magnetic beads, immunopanning and exploiting differential centripetal adhesion. Whereas rat OPCs are relatively simple to propagate in vitro, it has been difficult to expand mouse OPCs. Therefore, we evaluated the effects of oxygen levels, growth factors and extracellular matrix components to produce a simple and reproducible method to prepare large numbers of nearly homogenous cultures of primary mouse OPCs from postnatal day 0-2 mouse telencephala. Using the McCarthy and de Vellis mechanical separation method OPCs were separated from mixed culture of glial cells. When the OPCs were plated onto fibronectin coated tissue culture plates in a biochemically defined medium that contained fibroblast growth factor-2 (FGF-2) and platelet derived growth factor AA (PDGFAA), and they were maintained in a standard tissue culture incubator, they proliferated very slowly. By contrast, mouse OPCs doubled approximately every 7 days when maintained in a 2% oxygen, nitrogen buffered environment. After 3 passages, greater than 99% of these OPCs were NG2+/PDGFR+. In medium containing only FGF-2, mouse OPCs progressed to late stage OPCs whereupon A2B5 expression decreased and O4 expression increased. When these cells were differentiated between passages 1 and 3, the majority of the OPCs differentiated into MBP+ mature oligodendrocytes However, cells that were repeatedly passaged beyond 4 passages progressed to a late O4+ OPC (even with mitogens present) and when differentiated by mitogen removal a minority of the OPCs differentiated into MBP+ cells. These studies reveal significant differences between mouse and rat OPCs and an inhibitory role for oxygen in mouse OPC proliferation.

neuroscience↗

bioRxiv2020

Moderately Inducing Autophagy Reduces Tertiary Brain Injury After Perinatal Hypoxia-Ischemia

Recent studies of cerebral hypoxia-ischemia (HI) have highlighted slowly progressive neurodegeneration whose mechanisms remain elusive, but if blocked, could considerably improve long-term neurological function. We previously established that the cytokine transforming growth factor (TGF){beta}1 is highly elevated following HI and that delivering an antagonist for TGF{beta} receptor activin-like kinase 5 (ALK5) - SB505124 - 3 days after injury in a rat model of moderate pre-term HI significantly preserved the structural integrity of the thalamus and hippocampus as well as neurological functions associated with those brain structures. To elucidate the mechanism whereby ALK5 inhibition reduces cell death, we assessed levels of autophagy markers in neurons and found that SB505124 increased numbers of autophagosomes and levels of lipidated LC3 (light chain 3), a key protein known to mediate autophagy. However, those studies did not determine whether 1) SB was acting directly on the CNS and 2) whether directly inducing autophagy could decrease cell death and improve outcome. Here we show that administering an ALK5 antagonist 3 days after HI reduced actively apoptotic cells by [~]90% when assessed one week after injury. Ex vivo studies using the lysosomal inhibitor chloroquine confirmed that SB505124 enhanced autophagy flux in the injured hemisphere, with a significant accumulation of the autophagic proteins LC3 and p62 in SB505124 + chloroquine treated brain slices. We independently activated autophagy using the stimulatory peptide Tat-Beclin1 to determine if enhanced autophagy is directly responsible for improved outcomes. Administering Tat-Beclin1 starting 3 days after injury preserved the structural integrity of the hippocampus and thalamus with improved sensorimotor function. These data support the conclusion that intervening at this phase of injury represents a window of opportunity where stimulating autophagy is beneficial.

neuroscience↗

bioRxiv2020

Oligodendrocyte progenitor proliferation is disinhibited following traumatic brain injury in LIF heterozygous mice

Traumatic brain injury (TBI) is a significant problem that affects [~]500,000 children each year. As cell proliferation is disturbed by injury and is required for normal brain development, we investigated how a pediatric closed head injury (CHI) would affect the progenitors of the subventricular zone (SVZ). Additionally, we evaluated the contribution of Leukemia Inhibitory Factor (LIF) using LIF-heterozygous mice (LIF Het), as LIF is an injury-induced cytokine, known to influence neurogenesis and gliogenesis. CHIs were performed on P20 LIF Het and WT mice. Ki-67 staining and stereology revealed that cell proliferation increased [~]250% in injured LIF Het mice compared to the 30% increase observed in injured WT mice at 48 h post CHI. Furthermore, Olig2+ cell proliferation increased in the SVZ and white matter of LIF Het injured mice at 48 h recovery. Using an 8-color flow cytometry panel, the proliferation of three distinct multipotential progenitors were greater in LIF Het injured mice compared to WT injured mice. Early oligodendrocyte progenitor cell (OPC) proliferation was 6-fold higher in LIF Het injured mice compared to WT injured mice. In vitro, addition of LIF decreased overall cell proliferation and OPC proliferation compared to controls. Addition of LIF to OPC cultures induced an increase of phospho-Akt after 20 minutes and an increase of phospho-S6RP at 20 and 40 minutes of exposure, suggesting that LIF stimulates the mammalian target of Rapamycin pathway. Altogether, our data provide new insights into the regulatory role of LIF in suppressing neural progenitor cell proliferation after a mild TBI. Main PointsO_LIOPC proliferation is dis-inhibited in LIF haplodeficient mice. C_LIO_LILIF directly inhibits glial progenitor cell proliferation. C_LIO_LILIF stimulates the mTOR pathway. C_LI

neuroscience↗

bioRxiv2020

Perinatal IL-1-induced Inflammation Suppresses Tbr2+ Intermediate Progenitor Cell Proliferation in the Developing Hippocampus accompanied by Long-Term Behavioral Deficits

Meta-analyses have revealed associations between the incidence of maternal infections during pregnancy, premature birth, smaller brain volumes, and subsequent cognitive, motor and behavioral deficits as these children mature. Inflammation during pregnancy in rodents produces cognitive and behavioral deficits in the offspring that are similar to those reported in human studies. These deficits are accompanied by decreased neurogenesis and proliferation in the subgranular zone (SGZ) of the dentate gyrus (DG) of the hippocampus. As systemically administering interleukin-1 {beta} (IL-1{beta}) to neonatal mice recapitulates many of the brain abnormalities seen in premature babies including developmental delays, the goal of this study was to determine whether IL-1-mediated neuroinflammation would affect hippocampal growth during development to produce cognitive and behavioral abnormalities. For these studies, 10 ng/g IL-1{beta} was administered twice daily to Swiss Webster mice during the first 5 days of life, which increased hippocampal levels of IL-1 and acutely reduced the proliferation of Tbr2+ neural progenitors in the DG. In vitro, both IL-1 and IL-1{beta} produced G1/S cell cycle arrest that resulted in reduced progenitor cell proliferation within the transit amplifying progenitor cell cohort. By contrast, IL-1{beta} treatment increased neural stem cell frequency. Upon terminating IL-1{beta} treatment, the progenitor cell pool regained its proliferative capacity. An earlier study that used this in vivo model of perinatal inflammation showed that mice that received IL-1{beta} as neonates displayed memory deficits which suggested abnormal hippocampal function. To evaluate whether other cognitive and behavioral traits associated with hippocampal function would also be altered, mice were tested in tasks designed to assess exploratory and anxiety behavior as well as working and spatial memory. Interestingly, mice that received IL-1{beta} as neonates showed signs of anxiety in several behavioral assays during adolescence that were also evident in adulthood. Additionally, these mice did not display working memory deficits in adulthood, but they did display deficits in long-term spatial memory. Altogether, these data support the view that perinatal inflammation negatively affects the developing hippocampus producing behavioral deficits that persist into adulthood. These data provide a new perspective into the origin of the cognitive and behavioral impairments observed in prematurely-born sick infants. HighlightsO_LISystemic inflammation during the first 5 days of life increases hippocampal pro-inflammatory cytokines and chemokines C_LIO_LINeuroinflammation reduces Tbr2+ neural progenitor cell proliferation in the dentate gyrus. C_LIO_LIIL-1 arrests the cell cycle of Tbr-2+ progenitors and enriches for neural stem cells. C_LIO_LIAdolescent mice that experienced neonatal systemic inflammation have a persistent anxiety disorder. C_LIO_LIMice that experienced neonatal systemic inflammation have deficits in spatial memory as adults. C_LI

neuroscience↗

bioRxiv2020

Subventricular zone adult mouse neural stem cells and human glioblastoma stem cells require insulin receptor for self-renewal

The insulin receptor (IR) is an evolutionarily conserved signaling protein that regulates development and cellular metabolism. IR signaling regulates neurogenesis in Drosophila; however, a specific role for the IR in maintaining adult neural stem cells (NSCs) in mammals has not been investigated. We show that conditionally deleting the IR reduces adult NSCs of the subventricular zone by [~]70% accompanied by a corresponding increase in progenitors. IR deletion produced hyposmia due to aberrant olfactory bulb neurogenesis. Interestingly, hippocampal neurogenesis was not perturbed nor were hippocampal dependent behaviors. Highly aggressive proneural and mesenchymal glioblastomas (GBMs) had high IR/insulin-like growth factor (IGF) pathway gene expression, and isolated glioma stem cells had an aberrantly high ratio of IR:IGF1R receptors. Moreover, IR knockdown inhibited proneural and mesenchymal GBM tumorsphere growth. Altogether, these data demonstrate that the IR is essential for a subset of normal NSCs as well as for brain tumor cancer stem cell self-renewal.

neuroscience↗