A Spatial Transcriptomics Study of the Brain-Electrode Interface in Rat Motor Cortex

AbstractThe study of the foreign body reaction to implanted electrodes in the brain is an important area of research for the future development of neuroprostheses and experimental electrophysiology. After electrode implantation in the brain, microglial activation, reactive astrogliosis, and neuronal cell death create an environment immediately surrounding the electrode that is significantly altered from its homeostatic state. To uncover physiological changes potentially affecting device function and longevity, spatial transcriptomics was implemented in this preliminary study to identify changes in gene expression driven by electrode implantation. This RNA-sequencing technique (10x Genomics, Visium) uses spatially coded, RNA-binding oligonucleotides on a microscope slide to spatially identify each sequencing read. For these experiments, sections of rat motor cortex implanted with Michigan-style silicon electrodes were mounted on the Visium slide for processing. Each tissue section was labeled for neurons and astrocytes using immunohistochemistry to provide a spatial reference for mapping each sequencing read relative to the device tract. Results from rat motor cortex at 24 hours, 1 week, and 6 weeks post implantation showed up to 5811 differentially expressed genes between implanted and non-implanted tissue sections. Many of these genes are related to biological mechanisms previously reported in studies of the foreign body response to implanted electrodes, while others are novel to this study. These results will provide a foundation for future work to both improve and measure the effects of gene expression on the long-term stability of recordings from implanted electrodes in the brain. Ongoing work will expand on these initial observations as we gain a better understanding of the dynamic, molecular changes taking place in the brain in response to electrode implantation.

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Transcriptomic analysis of frontotemporal lobar degeneration with TDP-43 pathology reveals cellular alterations across multiple brain regions

10.1101/2021.10.06.21264635 ◽

2021 ◽

Author(s):

Rahat Hasan ◽

Jack Humphrey ◽

Conceicao Bettencourt ◽

Tammaryn Lashley ◽

Pietro Fratta ◽

...

Keyword(s):

Gene Expression ◽

Frontotemporal Lobar Degeneration ◽

Molecular Mechanisms ◽

Rna Binding ◽

Temporal Cortex ◽

Neuronal Loss ◽

Underlying Disease ◽

Brain Regions ◽

Neuronal Markers ◽

The Brain

Frontotemporal lobar degeneration (FTLD) is a group of heterogeneous neurodegenerative disorders affecting the frontal and temporal lobes of the brain. Nuclear loss and cytoplasmic aggregation of the RNA-binding protein TDP-43 represents the major FTLD pathology, known as FTLD-TDP. To date, there is no effective treatment for FTLD-TDP due to an incomplete understanding of the molecular mechanisms underlying disease development. Here we compared post-mortem tissue RNA-seq transcriptomes from the frontal cortex, temporal cortex and cerebellum between 28 controls and 30 FTLD-TDP patients to profile changes in cell-type composition, gene expression and transcript usage. We observed downregulation of neuronal markers in all three regions of the brain, accompanied by upregulation of microglia, astrocytes, and oligodendrocytes, as well as endothelial cells and pericytes, suggesting shifts in both immune activation and within the vasculature. We validate our estimates of neuronal loss using neuropathological atrophy scores and show that neuronal loss in the cortex can be mainly attributed to excitatory neurons, and that increases in microglial and endothelial cell expression are highly correlated with neuronal loss. All our analyses identified a strong involvement of the cerebellum in the neurodegenerative process of FTLD-TDP. Altogether, our data provides a detailed landscape of gene expression alterations to help unravel relevant disease mechanisms in FTLD.

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Induction of the Nrf2 Pathway by Sulforaphane Is Neuroprotective in a Rat Temporal Lobe Epilepsy Model

Antioxidants ◽

10.3390/antiox10111702 ◽

2021 ◽

Vol 10 (11) ◽

pp. 1702

Author(s):

Sereen Sandouka ◽

Tawfeeq Shekh-Ahmad

Keyword(s):

Oxidative Stress ◽

Cell Death ◽

Status Epilepticus ◽

Temporal Lobe Epilepsy ◽

Antioxidant Capacity ◽

Temporal Lobe ◽

Epileptiform Activity ◽

Neuronal Cell Death ◽

Neuronal Cell ◽

The Brain

Epilepsy is a chronic disease of the brain that affects over 65 million people worldwide. Acquired epilepsy is initiated by neurological insults, such as status epilepticus, which can result in the generation of ROS and induction of oxidative stress. Suppressing oxidative stress by upregulation of the transcription factor, nuclear factor erythroid 2-related factor 2 (Nrf2) has been shown to be an effective strategy to increase endogenous antioxidant defences, including in brain diseases, and can ameliorate neuronal damage and seizure occurrence in epilepsy. Here, we aim to test the neuroprotective potential of a naturally occurring Nrf2 activator sulforaphane, in in vitro epileptiform activity model and a temporal lobe epilepsy rat model. Sulforaphane significantly decreased ROS generation during epileptiform activity, restored glutathione levels, and prevented seizure-like activity-induced neuronal cell death. When given to rats after 2 h of kainic acid-induced status epilepticus, sulforaphane significantly increased the expression of Nrf2 and related antioxidant genes, improved oxidative stress markers, and increased the total antioxidant capacity in both the plasma and hippocampus. In addition, sulforaphane significantly decreased status epilepticus-induced neuronal cell death. Our results demonstrate that Nrf2 activation following an insult to the brain exerts a neuroprotective effect by reducing neuronal death, increasing the antioxidant capacity, and thus may also modify epilepsy development.

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Peroxiredoxin II Maintains the Mitochondrial Membrane Potential against Alcohol-Induced Apoptosis in HT22 Cells

Antioxidants ◽

10.3390/antiox9010001 ◽

2019 ◽

Vol 9 (1) ◽

pp. 1

Author(s):

Mei-Hua Jin ◽

Jia-Bin Yu ◽

Hu-Nan Sun ◽

Ying-Hua Jin ◽

Gui-Nan Shen ◽

...

Keyword(s):

Membrane Potential ◽

Mitochondrial Membrane Potential ◽

Mitochondrial Membrane ◽

Neuronal Cell Death ◽

Neuronal Cell ◽

Ht22 Cells ◽

Apoptotic Protein ◽

Intracellular Ros ◽

Induced Apoptosis ◽

The Brain

Excessive alcohol intake can significantly reduce cognitive function and cause irreversible learning and memory disorders. The brain is particularly vulnerable to alcohol-induced ROS damage; the hippocampus is one of the most sensitive areas of the brain for alcohol neurotoxicity. In the present study, we observed significant increasing of intracellular ROS accumulations in Peroxiredoxin II (Prx II) knockdown HT22 cells, which were induced by alcohol treatments. We also found that the level of ROS in mitochondrial was also increased, resulting in a decrease in the mitochondrial membrane potential. The phosphorylation of GSK3β (Ser9) and anti-apoptotic protein Bcl2 expression levels were significantly downregulated in Prx II knockdown HT22 cells, which suggests that Prx II knockdown HT22 cells were more susceptible to alcohol-induced apoptosis. Scavenging the alcohol-induced ROS with NAC significantly decreased the intracellular ROS levels, as well as the phosphorylation level of GSK3β in Prx II knockdown HT22 cells. Moreover, NAC treatment also dramatically restored the mitochondrial membrane potential and the cellular apoptosis in Prx II knockdown HT22 cells. Our findings suggest that Prx II plays a crucial role in alcohol-induced neuronal cell apoptosis by regulating the cellular ROS levels, especially through regulating the ROS-dependent mitochondrial membrane potential. Consequently, Prx II may be a therapeutic target molecule for alcohol-induced neuronal cell death, which is closely related to ROS-dependent mitochondria dysfunction.

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Neuroprotective Effect of Antioxidants in the Brain

International Journal of Molecular Sciences ◽

10.3390/ijms21197152 ◽

2020 ◽

Vol 21 (19) ◽

pp. 7152 ◽

Cited By ~ 1

Author(s):

Kyung Hee Lee ◽

Myeounghoon Cha ◽

Bae Hwan Lee

Keyword(s):

Oxidative Stress ◽

Neurodegenerative Diseases ◽

Intracellular Signaling ◽

Neuronal Damage ◽

Neuroprotective Effect ◽

Neuronal Cell Death ◽

Neuronal Cell ◽

High Energy ◽

Antioxidant Compounds ◽

The Brain

The brain is vulnerable to excessive oxidative insults because of its abundant lipid content, high energy requirements, and weak antioxidant capacity. Reactive oxygen species (ROS) increase susceptibility to neuronal damage and functional deficits, via oxidative changes in the brain in neurodegenerative diseases. Overabundance and abnormal levels of ROS and/or overload of metals are regulated by cellular defense mechanisms, intracellular signaling, and physiological functions of antioxidants in the brain. Single and/or complex antioxidant compounds targeting oxidative stress, redox metals, and neuronal cell death have been evaluated in multiple preclinical and clinical trials as a complementary therapeutic strategy for combating oxidative stress associated with neurodegenerative diseases. Herein, we present a general analysis and overview of various antioxidants and suggest potential courses of antioxidant treatments for the neuroprotection of the brain from oxidative injury. This review focuses on enzymatic and non-enzymatic antioxidant mechanisms in the brain and examines the relative advantages and methodological concerns when assessing antioxidant compounds for the treatment of neurodegenerative disorders.

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Heme–Hemopexin Complex Attenuates Neuronal Cell Death and Stroke Damage

Journal of Cerebral Blood Flow & Metabolism ◽

10.1038/jcbfm.2009.19 ◽

2009 ◽

Vol 29 (5) ◽

pp. 953-964 ◽

Cited By ~ 62

Author(s):

Rung-chi Li ◽

Sofiyan Saleem ◽

Gehua Zhen ◽

Wangsen Cao ◽

Hean Zhuang ◽

...

Keyword(s):

Cortical Neurons ◽

Neuronal Cell Death ◽

Neuronal Cell ◽

Artery Occlusion ◽

Neuronal Cultures ◽

Tert Butyl Hydroperoxide ◽

Primary Mouse ◽

Free Heme ◽

Cerebral Artery Occlusion ◽

The Brain

Hemoproteins undergo degradation during hypoxic/ischemic conditions, but the prooxidant free heme that is released cannot be recycled and must be degraded. The extracellular heme associates with its high-affinity binding protein, hemopexin (HPX). Hemopexin is shown here to be expressed by cortical neurons and it is present in mouse cerebellum, cortex, hippocampus, and striatum. Using the transient ischemia model (90-min middle cerebral artery occlusion followed by 96-h survival), we provide evidence that HPX is protective in the brain, as neurologic deficits and infarct volumes were significantly greater in HPX−/− than in wild-type mice. Addressing the potential protective HPX cellular pathway, we observed that exogenous free heme decreased cell survival in primary mouse cortical neuron cultures, whereas the heme bound to HPX was not toxic. Heme-HPX complexes induce HO1 and, consequently, protect primary neurons against the toxicity of both heme and prooxidant tert-butyl hydroperoxide; such protection was decreased in HO1−/− neuronal cultures. Taken together, these data show that HPX protects against heme-induced toxicity and oxidative stress and that HO1 is required. We propose that the heme-HPX system protects against stroke-related damage by maintaining a tight balance between free and bound heme. Thus, regulating extracellular free heme levels, such as with HPX, could be neuroprotective.

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Persisting Rickettsia typhi Causes Fatal Central Nervous System Inflammation

Infection and Immunity ◽

10.1128/iai.00034-16 ◽

2016 ◽

Vol 84 (5) ◽

pp. 1615-1632 ◽

Cited By ~ 11

Author(s):

Anke Osterloh ◽

Stefanie Papp ◽

Kristin Moderzynski ◽

Svenja Kuehl ◽

Ulricke Richardt ◽

...

Keyword(s):

Central Nervous System ◽

Nervous System ◽

Neuronal Cell Death ◽

Neuronal Cell ◽

Rickettsia Typhi ◽

Content Type ◽

Inflammatory Phenotype ◽

Obligate Intracellular Bacteria ◽

Immunocompromised Mice ◽

The Brain

Rickettsioses are emerging febrile diseases caused by obligate intracellular bacteria belonging to the familyRickettsiaceae. Rickettsia typhibelongs to the typhus group (TG) of this family and is the causative agent of endemic typhus, a disease that can be fatal. In the present study, we analyzed the course ofR. typhiinfection in C57BL/6 RAG1−/−mice. Although these mice lack adaptive immunity, they developed only mild and temporary symptoms of disease and survivedR. typhiinfection for a long period of time. To our surprise, 3 to 4 months after infection, C57BL/6 RAG1−/−mice suddenly developed lethal neurological disorders. Analysis of these mice at the time of death revealed high bacterial loads, predominantly in the brain. This was accompanied by a massive expansion of microglia and by neuronal cell death. Furthermore, high numbers of infiltrating CD11b+macrophages were detectable in the brain. In contrast to the microglia, these cells harboredR. typhiand showed an inflammatory phenotype, as indicated by inducible nitric oxide synthase (iNOS) expression, which was not observed in the periphery. Having shown thatR. typhipersists in immunocompromised mice, we finally asked whether the bacteria are also able to persist in resistant C57BL/6 and BALB/c wild-type mice. Indeed,R. typhicould be recultivated from lung, spleen, and brain tissues from both strains even up to 1 year after infection. This is the first report demonstrating persistence and reappearance ofR. typhi, mainly restricted to the central nervous system in immunocompromised mice.

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Mud sticks after all: Chronically implanted microelectrodes but not electrical stimulation cause c-fos expression along their trajectory

10.1101/203877 ◽

2017 ◽

Author(s):

Patrick Pflüger ◽

Richard C. Pinnell ◽

Nadja Martini ◽

Ulrich G. Hofmann

Keyword(s):

Brain Tissue ◽

Neuronal Cell Death ◽

Neuronal Cell ◽

Cell Loss ◽

Glial Scar ◽

Tissue Response ◽

High Frequency Stimulation ◽

Dorsolateral Striatum ◽

Frequency Stimulation ◽

The Brain

ABSTRACTThe goal of CNS implanted devices is to build a stable brain-machine-interface. The brain tissue response to the foreign body limits the functionality and viability of this brain-machine connection. Notably the astrocytic glial scar formation and inflammation with resulting neuronal cell loss is considered to be responsible for the signal deterioration over time. We chronically implanted a polyimide microelectrode in the dorsolateral striatum of rats. First, we analyzed the c-fos immunoreactivity following high frequency stimulation (HFS) of the dorsolateral striatum and second, using GFAP and ED1 immunocytochemistry, the brain tissue response. Acute as well as chronic HFS showed no significant change of neuronal c-fos expression in the dorsolateral striatum and corresponding cortical areas. We found that the sole chronic implantation of a polyimide microelectrode leads to a reaction of the surrounding neurons, i.e. c-fos expression, along the implantation trajectory. We also observed the formation of a glial scar around the microelectrode with a low number of inflammation cells. Histological and statistical analysis of NeuN positive cells showed no ‘kill zone’, which accompanied neuronal cell death around the implantation site.

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Levosimendan prevents tau pathology by inhibiting disulfide-linked tau oligomerization posing as a promising anti-tau therapeutics

10.21203/rs.3.rs-128169/v1 ◽

2020 ◽

Author(s):

Yun Kyung Kim ◽

Sungsu Lim ◽

Seulgi Shin ◽

Ha Eun Lee ◽

Ji Yeon Song ◽

...

Keyword(s):

Therapeutic Strategy ◽

Isotope Labeling ◽

Neuronal Cell Death ◽

Neuronal Cell ◽

Tau Pathology ◽

Tau Oligomers ◽

Disease Modifying Therapy ◽

Cellular Context ◽

Targeted Drug Discovery ◽

The Brain

Abstract Tau oligomers play critical roles in tau pathology, responsible for neuronal cell death and transmitting the disease in the brain. Accordingly, preventing tau oligomerization becomes an important therapeutic strategy to treat tauopathies including Alzheimer’s disease, however progress has been slow due to difficulties of detecting tau oligomers in cellular context. Toward tau-targeted drug discovery, our group have developed a tau-BiFC platform to monitor and quantify tau oligomerization. By using the tau-BiFC platform, we screened 1,018 compounds in FDA-approved & Passed Phase I drug library, and identified levosimendan as a potent anti-tau agent inhibiting tau oligomerization. 14C-isotope labeling of levosimendan identified that levosimendan covalently bound to tau cysteines, directly inhibiting disulfide-linked tau oligomerization. In addition, levosimendan was able to disassemble tau oligomers into monomers, and rescuing neurons from aggregation states. In comparison, the well-known anti-tau agents, methylene blue (MB) and LMTM, failed to protect neurons from tau-mediated toxicity, generating high-molecular weight tau oligomers. The administration of levosimendan also suppressed tau pathology in the brain, preventing cognitive declines in TauP301L-BiFC transgenic mice. Although careful validation is required, here we present the potential of levosimendan as a disease modifying therapy for tauopathies targeting tau oligomerization.

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The prion protein gene: a role in mouse embryogenesis?

Development ◽

10.1242/dev.115.1.117 ◽

1992 ◽

Vol 115 (1) ◽

pp. 117-122 ◽

Cited By ~ 1

Author(s):

J. Manson ◽

J.D. West ◽

V. Thomson ◽

P. McBride ◽

M.H. Kaufman ◽

...

Keyword(s):

Gene Expression ◽

Nervous System ◽

Prion Protein ◽

In Situ Hybridisation ◽

Neuronal Cell ◽

Normal Function ◽

Cell Populations ◽

Specific Expression ◽

The Brain ◽

Prp Gene

The neural membrane glycoprotein PrP (prion protein) has a key role in the development of scrapie and related neurodegenerative diseases. During pathogenesis, PrP accumulates in and around cells of the brain from which it can be isolated in a disease-specific, protease-resistant form. Although the involvement of PrP in the pathology of these diseases has long been known, the normal function of PrP remains unknown. Previous studies have shown that the PrP gene is expressed tissue specifically in adult animals, the highest levels in the brain, with intermediate levels in heart and lung and low levels in spleen. Prenatally, PrP mRNA has been detected in the brain of rat and hamster just prior to birth. In this study we have examined the expression of the PrP gene during mouse embryonic development by in situ hybridisation and observed dramatic regional and temporal gene expression in the embryo. Transcripts were detected in developing brain and spinal cord by 13.5 days. In addition, PrP gene expression was detected in the peripheral nervous system, in ganglia and nerve trunks of the sympathetic nervous system and neural cell populations of sensory organs. Expression of the PrP gene was not limited to neuronal cells, but was also detected in specific non-neuronal cell populations of the 13.5 and 16.5 day embryos and in extra-embryonic tissues from 6.5 days. This cell-specific expression suggests a pleiotropic role for PrP during development.

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Abstract P801: Impact of Oxidized Phospholipids on Outcomes From Cerebral Ischemia and Reperfusion Injury

Stroke ◽

10.1161/str.52.suppl_1.p801 ◽

2021 ◽

Vol 52 (Suppl_1) ◽

Author(s):

Jin Yu ◽

Hong Zhu ◽

Calvin Yeang ◽

Joseph L Witztum ◽

Sotirios Tsimikas ◽

...

Keyword(s):

Cell Death ◽

Cerebral Ischemia ◽

Neuronal Cell Death ◽

Neuronal Cell ◽

Ischemia And Reperfusion ◽

Oxidized Phospholipids ◽

Ischemia And Reperfusion Injury ◽

Cerebral Ischemia And Reperfusion ◽

The Brain

The mechanisms leading to oxidative stress and cellular dysfunction during stroke are not well understood. To test the hypothesis that transient cerebral artery occlusion (MCAo) in mice results in the generation of oxidized phospholipids (oxPLs) that contribute to neuronal cell death and glial activation. Both in vitro and in vivo cerebral ischemia and reperfusion injury (IRI) resulted in the elevation of specific oxPLs. Neuronal cell death was determined in the presence of oxPLs and the natural oxPL E06 antibody protected the cells from the toxic effects. IRI in mice gave rise to increased immunoreactivity of oxPLs in the brain. E06 reduced inflammatory markers in the brain following IRI, including iba-1, GFAP and inflammatory cytokines. In addition, oxPLs gave rise to M1 and Mox microglial phenotypes which was reversed in the presence of E06 and elicited a more M2 phenotype. Nrf2 deficient mice show increased infarct volumes and microglia from Nrf2 -/- mice show a reduction in Mox gene expression, and E06 protects both mice and cells from the Nrf2 deficit. Cerebral IRI generates oxPLs which triggers neuronal cell loss and inflammation and inactivation of oxPLs in vivo reduces infarct volume and improves outcomes.

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