Biology subjects

Ebert, A. D.

Publications and source records attributed to Ebert, A. D..

5 recordsLinked to original sources

bioRxiv2026

Cytomegalovirus Infection in Human Cortical Organoids Induces Unique Developmental and Viral Substates

Human Cytomegalovirus (HCMV) is a ubiquitous {beta}-herpesvirus with exposure resulting in a life-long infection. Severe HCMV disease can occur in conditions of insufficient immunity, and this includes congenital infection. Infection of the developing brain can cause severe birth defects including microcephaly and sensorineural hearing loss. Also, increasing evidence suggests the contribution of HCMV infection in adult CNS diseases. Studying HCMV replication and its impact on CNS is restricted by host tropism and anatomy. In these studies, we define the impact of infection on healthy iPSC-derived cortical organoids using single cell RNA sequencing. We uncovered 16 cell type clusters in uninfected tissues using the Human Neural Organoid Cell Atlas. Following infection by HCMV expressing GFP, several clusters were altered in both GFP-positive and GFP-negative populations, including the likely transition of the Glutamatergic/GABAergic Neuron cluster into a CMV-Infected Cell cluster. Expressions of viral genes varied between cells and cell types, requiring us to introduce a TC (temporal class) indexing score to account for varying stages of infection. This analysis in conjunction with machine learning approaches revealed cells that are likely producing de novo HCMV along with several viral sub-states. Several viral sub-states had significant enrichments of genes involved in epithelial-to-mesenchymal (EMT) transition, including expression of EpCAM. We independently verified HCMV-induction of EpCAM protein expression in cortical organoids and glutamatergic neurons. In summary, our studies reveal unique features of HCMV infection of cortical organoid tissues, including varying viral sub-states and tropisms, and introduced new approaches to analyze these multi-dimensional complex data sets.

microbiology↗

bioRxiv2024

Stabilizing microtubules aids neurite structure and disrupts syncytia formation in human cytomegalovirus-infected human forebrain neurons

Human cytomegalovirus (HCMV) is a prolific human herpesvirus that infects most individuals by adulthood. While typically asymptomatic in adults, congenital infection can induce serious neurological symptoms including hearing loss, visual deficits, cognitive impairment, and microcephaly in 10-15% of cases. HCMV has been shown to infect most neural cells with our group recently demonstrating this capacity in stem cell-derived forebrain neurons. Infection of neurons induces deleterious effects on calcium dynamics and electrophysiological function paired with gross restructuring of neuronal morphology. Here, we utilize an iPSC-derived model of the human forebrain to demonstrate how HCMV infection induces syncytia, drives neurite retraction, and remodels microtubule networks to promote viral production and release. We establish that HCMV downregulates microtubule associated proteins at 14 days postinfection while simultaneously sparing other cytoskeletal elements, and this includes HCMV-driven alterations to microtubule stability. Further, we pharmacologically modulate microtubule dynamics using paclitaxel (stabilize) and colchicine (destabilize) to examine the effects on neurite structure, syncytial morphology, assembly compartment formation, and viral release. With paclitaxel, we found improvement of neurite outgrowth with a corresponding disruption to HCMV-induced syncytia formation and Golgi network disruptions but with limited impact on viral titers. Together, these data suggest that HCMV infection-induced disruption of microtubules in human cortical neurons can be partially mitigated with microtubule stabilization, suggesting a potential avenue for future neuroprotective therapeutic exploration. IMPORTANCEInfection by human cytomegalovirus (HCMV) continues to cause significant damage to human health. In the absence of a vaccine, vertical transmission from mother to fetus can result in profound neurological damage impacting quality of life. These studies focus on understanding the impact of HCMV infection on forebrain cortical neurons derived from iPSCs. We show that infection results in loss of neurite extension accompanied by cell-to-cell fusion. These pathogenic changes involve HCMV infection-mediated disruption to the microtubule network. Upon addition of the microtubule stabilization agent paclitaxel, the structural damage was limited, but infection still progressed to produce infectious particles. This work is part of our continued efforts to define putative strategies to limit HCMV-induced neurological damage.

neuroscience↗

bioRxiv2021

Nitric Oxide Attenuates Human Cytomegalovirus Infection yet Disrupts Neural Cell Differentiation and Tissue Organization

Human cytomegalovirus (HCMV) is a prevalent betaherpesvirus that is asymptomatic in healthy individuals but can cause serious disease in immunocompromised patients. HCMV is also the leading cause of viral-mediated birth defects. Many of these defects manifest within the central nervous system and include microcephaly, sensorineural hearing loss, and cognitive developmental delays. Nitric oxide is a critical effector molecule produced as a component of the innate immune response during infection. Using a 3-dimensional cortical organoid model, we demonstrate that nitric oxide inhibits HCMV spread and simultaneously disrupts neural rosette structures resulting in tissue disorganization. Nitric oxide also attenuates HCMV replication in 2-dimensional cultures of neural progenitor cells (NPCs), a prominent cell type in cortical organoids that differentiate into neurons and glial cells. The multipotency factor SOX2 was decreased during nitric oxide exposure, suggesting early neural differentiation is affected. Maximal mitochondrial respiration was also reduced in both uninfected and infected NPCs. We determined this reduction likely influences neural differentiation as neurons (Tuj1+GFAP-Nestin-) and glial populations (Tuj1-GFAP+Nestin-) were reduced following differentiation. We also observed changes in calcium signaling during exposure to nitric oxide with increased cellular response to ATP (purinergic receptors) and KCl (voltage gated calcium channels). Importantly, nitric oxide could not rescue HCMV-mediated defects in calcium response. Our studies indicate a prominent, immunopathogenic role of nitric oxide in promoting developmental defects within the brain despite its antiviral activity during congenital HCMV infection. Author summaryHuman cytomegalovirus (HCMV) infection can result in serious disease to immunocompromised individuals. HCMV is also the leading cause of viral-mediated congenital birth defects. Congenitally-infected infants can have a variety of symptoms, including microcephaly, sensorineural hearing loss, and developmental delays. The use of 3-dimensional (3-D) cortical organoids to model infection of the fetal brain has advanced the current understanding of developmental defects and allowed a broader investigation of the mechanisms behind disease. Here, we investigate the effect of nitric oxide, a critical effector molecule, on cortical development and HCMV infection. We demonstrate that nitric oxide plays an antiviral role during infection yet results in significant disorganization to cortical tissue. Despite inhibiting viral replication in neural progenitor cells, nitric oxide contributes to differentiation defects of these cells and does not rescue functional consequences of HCMV infection on calcium signaling. Our results indicate that immunopathogenic consequences of nitric oxide during congenital infection promote developmental defects that undermine its antiviral activity.

microbiology↗

bioRxiv2021

Viral mediated knockdown of GATA6 in SMA iPSC-derived astrocytes prevents motor neuron loss and microglial activation

Spinal muscular atrophy (SMA), a pediatric genetic disorder, is characterized by the profound loss of spinal cord motor neurons and subsequent muscle atrophy and death. Although the mechanisms underlying motor neuron loss are not entirely clear, data from our work and others support the idea that glial cells contribute to disease pathology. GATA6, a transcription factor that we have previously shown to be upregulated in SMA astrocytes, is negatively regulated by SMN and can increase the expression of inflammatory regulator NF{kappa}B. In this study, we identified upregulated GATA6 as a contributor to increased activation, pro-inflammatory ligand production, and neurotoxicity in spinal-cord patterned astrocytes differentiated from SMA patient induced pluripotent stem cells. Reducing GATA6 expression in SMA astrocytes via lentiviral infection ameliorated these effects to healthy control levels. Additionally, we found that SMA astrocytes contribute to SMA microglial phagocytosis, which was again decreased by lentiviral-mediated knockdown of GATA6. Together these data identify a role of GATA6 in SMA astrocyte pathology and further highlight glia as important targets of therapeutic intervention in SMA.

neuroscience↗

bioRxiv2021

Downregulation of Neurodevelopmental Gene Expression in iPSC-Derived Cerebral Organoids Upon Infection by Human Cytomegalovirus

Human cytomegalovirus (HCMV) is a beta herpesvirus that, upon congenital infection, can cause severe birth defects including vision and hearing loss, microcephaly, and seizures. Currently, no approved treatment options exist for in utero infections. We previously demonstrated that HCMV infection decreases calcium signaling responses and alters neuronal differentiation in induced pluripotent stem cell (iPSC) derived neural progenitor cells (NPCs). Here we aimed to determine the impact of infection on the transcriptome in developing human neurons using iPSC-derived 3-dimensional cerebral organoids. We infected iPSC-derived cerebral organoids with HCMV encoding eGFP and sorted cell populations based on GFP signal strength. Significant transcriptional downregulation was observed including in key neurodevelopmental gene pathways in both the GFP (+) and intermediate groups. Interestingly, the GFP (-) group also showed downregulation of the same targets indicating a mismatch between GFP expression and viral infection. Using a modified HCMV virus destabilizing IE 1 and 2 proteins, we still observed significant downregulation of neurodevelopmental gene expression in infected neural progenitor cells. Together, these data indicate that IE viral proteins are not the main drivers of neurodevelopmental gene dysregulation in HCMV infected neural tissues suggesting therapeutically targeting IE gene expression is insufficient to restore neural differentiation and function.

cell biology↗