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Häussler U, Neres J, Vandenplas C, Eykens C, Kadiu I, Schramm C, Fleurance R, Stanley P, Godard P, de Mot L, van Eyll J, Knobeloch KP, Haas CA, Dedeurwaerdere S. Downregulation of Ubiquitin-Specific Protease 15 (USP15) Does Not Provide Therapeutic Benefit in Experimental Mesial Temporal Lobe Epilepsy. Mol Neurobiol 2024; 61:2367-2389. [PMID: 37874479 PMCID: PMC10973041 DOI: 10.1007/s12035-023-03692-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Accepted: 10/04/2023] [Indexed: 10/25/2023]
Abstract
Structural epilepsies display complex immune activation signatures. However, it is unclear which neuroinflammatory pathways drive pathobiology. Transcriptome studies of brain resections from mesial temporal lobe epilepsy (mTLE) patients revealed a dysregulation of transforming growth factor β, interferon α/β, and nuclear factor erythroid 2-related factor 2 pathways. Since these pathways are regulated by ubiquitin-specific proteases (USP), in particular USP15, we hypothesized that USP15 blockade may provide therapeutic relief in treatment-resistant epilepsies. For validation, transgenic mice which either constitutively or inducibly lack Usp15 gene expression underwent intrahippocampal kainate injections to induce mTLE. We show that the severity of status epilepticus is unaltered in mice constitutively lacking Usp15 compared to wild types. Cell death, reactive gliosis, and changes in the inflammatory transcriptome were pronounced at 4 days after kainate injection. However, these brain inflammation signatures did not differ between genotypes. Likewise, induced deletion of Usp15 in chronic epilepsy did not affect seizure generation, cell death, gliosis, or the transcriptome. Concordantly, siRNA-mediated knockdown of Usp15 in a microglial cell line did not impact inflammatory responses in the form of cytokine release. Our data show that a lack of USP15 is insufficient to modulate the expression of relevant neuroinflammatory pathways in an mTLE mouse model and do not support targeting USP15 as a therapeutic approach for pharmacoresistant epilepsy.
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Affiliation(s)
- Ute Häussler
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Breisacher Strasse 64, 79106, Freiburg, Germany.
- BrainLinks-BrainTools Center, University of Freiburg, Georges-Koehler-Allee 201, 79110, Freiburg, Germany.
| | - João Neres
- Early Solutions, UCB Biopharma SRL, Chemin du Foriest, 1420, Braine L'Alleud, Belgium
| | - Catherine Vandenplas
- Early Solutions, UCB Biopharma SRL, Chemin du Foriest, 1420, Braine L'Alleud, Belgium
| | - Caroline Eykens
- Early Solutions, UCB Biopharma SRL, Chemin du Foriest, 1420, Braine L'Alleud, Belgium
| | - Irena Kadiu
- Early Solutions, UCB Biopharma SRL, Chemin du Foriest, 1420, Braine L'Alleud, Belgium
| | - Carolin Schramm
- Early Solutions, UCB Biopharma SRL, Chemin du Foriest, 1420, Braine L'Alleud, Belgium
| | - Renaud Fleurance
- Early Solutions, UCB Biopharma SRL, Chemin du Foriest, 1420, Braine L'Alleud, Belgium
| | - Phil Stanley
- Early Development Statistics, UCB Celltech, 208 Bath Road, Slough, Berkshire, SL1 3WE, UK
| | - Patrice Godard
- Early Solutions, UCB Biopharma SRL, Chemin du Foriest, 1420, Braine L'Alleud, Belgium
| | - Laurane de Mot
- Early Solutions, UCB Biopharma SRL, Chemin du Foriest, 1420, Braine L'Alleud, Belgium
| | - Jonathan van Eyll
- Early Solutions, UCB Biopharma SRL, Chemin du Foriest, 1420, Braine L'Alleud, Belgium
| | - Klaus-Peter Knobeloch
- Institute for Neuropathology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Breisacher Strasse 64, 79106, Freiburg, Germany.
- CIBSS - Centre for Integrative Biological Signalling Studies, Freiburg, Germany.
| | - Carola A Haas
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Breisacher Strasse 64, 79106, Freiburg, Germany
- BrainLinks-BrainTools Center, University of Freiburg, Georges-Koehler-Allee 201, 79110, Freiburg, Germany
- Center for Basics in NeuroModulation, Faculty of Medicine, University of Freiburg, 79106, Freiburg, Germany
- Bernstein Center Freiburg, University of Freiburg, Hansastr. 9a, 79104, Freiburg, Germany
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Kleis P, Paschen E, Häussler U, Haas CA. Low frequency stimulation for seizure suppression: Identification of optimal targets in the entorhinal-hippocampal circuit. Brain Stimul 2024; 17:395-404. [PMID: 38531502 DOI: 10.1016/j.brs.2024.03.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 03/15/2024] [Accepted: 03/22/2024] [Indexed: 03/28/2024] Open
Abstract
BACKGROUND Mesial temporal lobe epilepsy (MTLE) with hippocampal sclerosis (HS) is a common form of drug-resistant focal epilepsy in adults. Treatment for pharmacoresistant patients remains a challenge, with deep brain stimulation (DBS) showing promise for alleviating intractable seizures. This study explores the efficacy of low frequency stimulation (LFS) on specific neuronal targets within the entorhinal-hippocampal circuit in a mouse model of MTLE. OBJECTIVE Our previous research demonstrated that LFS of the medial perforant path (MPP) fibers in the sclerotic hippocampus reduced seizures in epileptic mice. Here, we aimed to identify the critical neuronal population responsible for this antiepileptic effect by optogenetically stimulating presynaptic and postsynaptic compartments of the MPP-dentate granule cell (DGC) synapse at 1 Hz. We hypothesize that specific targets for LFS can differentially influence seizure activity depending on the cellular identity and location within or outside the seizure focus. METHODS We utilized the intrahippocampal kainate (ihKA) mouse model of MTLE and targeted specific neural populations using optogenetic stimulation. We recorded intracranial neuronal activity from freely moving chronically epileptic mice with and without optogenetic LFS up to 3 h. RESULTS We found that LFS of MPP fibers in the sclerotic hippocampus effectively suppressed epileptiform activity while stimulating principal cells in the MEC had no impact. Targeting DGCs in the sclerotic septal or non-sclerotic temporal hippocampus with LFS did not reduce seizure numbers but shortened the epileptiform bursts. CONCLUSION Presynaptic stimulation of the MPP-DGC synapse within the sclerotic hippocampus is critical for seizure suppression via LFS.
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Affiliation(s)
- Piret Kleis
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany; Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Enya Paschen
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany; Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Ute Häussler
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany; BrainLinks-BrainTools Center, University of Freiburg, Freiburg, Germany
| | - Carola A Haas
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany; BrainLinks-BrainTools Center, University of Freiburg, Freiburg, Germany.
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Paschen E, Kleis P, Vieira DM, Heining K, Boehler C, Egert U, Häussler U, Haas CA. On-demand low-frequency stimulation for seizure control: efficacy and behavioural implications. Brain 2024; 147:505-520. [PMID: 37675644 DOI: 10.1093/brain/awad299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 07/24/2023] [Accepted: 08/28/2023] [Indexed: 09/08/2023] Open
Abstract
Mesial temporal lobe epilepsy (MTLE), the most common form of focal epilepsy in adults, is often refractory to medication and associated with hippocampal sclerosis. Deep brain stimulation represents an alternative treatment option for drug-resistant patients who are ineligible for resective brain surgery. In clinical practice, closed-loop stimulation at high frequencies is applied to interrupt ongoing seizures, yet has (i) a high incidence of false detections; (ii) the drawback of delayed seizure-suppressive intervention; and (iii) limited success in sclerotic tissue. As an alternative, low-frequency stimulation (LFS) has been explored recently in patients with focal epilepsies. In preclinical epilepsy models, hippocampal LFS successfully prevented seizures when applied continuously. Since it would be advantageous to reduce the stimulation load, we developed a protocol for on-demand LFS. Given the importance of the hippocampus for navigation and memory, we investigated potential consequences of LFS on hippocampal function. To this end, we used the intrahippocampal kainate mouse model, which recapitulates the key features of MTLE, including spontaneous seizure activity and hippocampal sclerosis. Specifically, our online detection algorithm monitored epileptiform activity in hippocampal local field potential recordings and identified short epileptiform bursts preceding focal seizure clusters, triggering hippocampal LFS to stabilize the network state. To probe behavioural performance, we tested the acute influence of LFS on anxiety-like behaviour in the light-dark box test, spatial and non-spatial memory in the object location memory and novel object recognition test, as well as spatial navigation and long-term memory in the Barnes maze. On-demand LFS was almost as effective as continuous LFS in preventing focal seizure clusters but with a significantly lower stimulation load. When we compared the behavioural performance of chronically epileptic mice to healthy controls, we found that both groups were equally mobile, but epileptic mice displayed an increased anxiety level, altered spatial learning strategy and impaired memory performance. Most importantly, with the application of hippocampal LFS before behavioural training and test sessions, we could rule out deleterious effects on cognition and even show an alleviation of deficits in long-term memory recall in chronically epileptic mice. Taken together, our findings may provide a promising alternative to current therapies, overcoming some of their major limitations, and inspire further investigation of LFS for seizure control in focal epilepsy syndromes.
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Affiliation(s)
- Enya Paschen
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center-University of Freiburg, Faculty of Medicine, Freiburg 79106, Germany
- Faculty of Biology, University of Freiburg, Freiburg 79104, Germany
| | - Piret Kleis
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center-University of Freiburg, Faculty of Medicine, Freiburg 79106, Germany
- Faculty of Biology, University of Freiburg, Freiburg 79104, Germany
| | - Diego M Vieira
- Biomicrotechnology, Department of Microsystems Engineering-IMTEK, Faculty of Engineering, University of Freiburg, Freiburg 79108, Germany
| | - Katharina Heining
- Department of Neuroscience, Karolinska Institutet, Stockholm 17177, Sweden
| | - Christian Boehler
- Department of Microsystems Engineering (IMTEK), Bioelectronic Microtechnology (BEMT), University of Freiburg, Freiburg 79108, Germany
| | - Ulrich Egert
- Biomicrotechnology, Department of Microsystems Engineering-IMTEK, Faculty of Engineering, University of Freiburg, Freiburg 79108, Germany
- BrainLinks-BrainTools Center, University of Freiburg, Freiburg 79110, Germany
| | - Ute Häussler
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center-University of Freiburg, Faculty of Medicine, Freiburg 79106, Germany
- BrainLinks-BrainTools Center, University of Freiburg, Freiburg 79110, Germany
| | - Carola A Haas
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center-University of Freiburg, Faculty of Medicine, Freiburg 79106, Germany
- BrainLinks-BrainTools Center, University of Freiburg, Freiburg 79110, Germany
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Jean G, Carton J, Haq K, Musto AE. The role of dendritic spines in epileptogenesis. Front Cell Neurosci 2023; 17:1173694. [PMID: 37601280 PMCID: PMC10433379 DOI: 10.3389/fncel.2023.1173694] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 07/06/2023] [Indexed: 08/22/2023] Open
Abstract
Epilepsy is a chronic central nervous system (CNS) disease associated with high morbidity. To date, there is no known disease-modifying therapy for epilepsy. A leading hypothesis for a mechanism of epileptogenesis is the generation of aberrant neuronal networks. Although the underlying biological mechanism is not clear, scientific evidence indicates that it is associated with a hyperexcitable synchronous neuronal network and active dendritic spine plasticity. Changes in dendritic spine morphology are related to altered expression of synaptic cytoskeletal proteins, inflammatory molecules, neurotrophic factors, and extracellular matrix signaling. However, it remains to be determined if these aberrant dendritic spine formations lead to neuronal hyperexcitability and abnormal synaptic connections or whether they constitute an underlying mechanism of seizure susceptibility. Focusing on dendritic spine machinery as a potential target for medications could limit or reverse the development of epilepsy.
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Affiliation(s)
- Gary Jean
- Medical Program, School of Medicine, Eastern Virginia Medical School, Norfolk, VA, United States
| | - Joseph Carton
- Medical Program, School of Medicine, Eastern Virginia Medical School, Norfolk, VA, United States
| | - Kaleem Haq
- Department of Pathology and Anatomy, Eastern Virginia Medical School, Norfolk, VA, United States
| | - Alberto E. Musto
- Department of Pathology and Anatomy, Eastern Virginia Medical School, Norfolk, VA, United States
- Department of Neurology, Eastern Virginia Medical School, Norfolk, VA, United States
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Franz J, Barheier N, Wilms H, Tulke S, Haas CA, Häussler U. Differential vulnerability of neuronal subpopulations of the subiculum in a mouse model for mesial temporal lobe epilepsy. Front Cell Neurosci 2023; 17:1142507. [PMID: 37066079 PMCID: PMC10090355 DOI: 10.3389/fncel.2023.1142507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 03/06/2023] [Indexed: 03/30/2023] Open
Abstract
Selective loss of inhibitory interneurons (INs) that promotes a shift toward an excitatory predominance may have a critical impact on the generation of epileptic activity. While research on mesial temporal lobe epilepsy (MTLE) has mostly focused on hippocampal changes, including IN loss, the subiculum as the major output region of the hippocampal formation has received less attention. The subiculum has been shown to occupy a key position in the epileptic network, but data on cellular alterations are controversial. Using the intrahippocampal kainate (KA) mouse model for MTLE, which recapitulates main features of human MTLE such as unilateral hippocampal sclerosis and granule cell dispersion, we identified cell loss in the subiculum and quantified changes in specific IN subpopulations along its dorso-ventral axis. We performed intrahippocampal recordings, FluoroJade C-staining for degenerating neurons shortly after status epilepticus (SE), fluorescence in situ hybridization for glutamic acid decarboxylase (Gad) 67 mRNA and immunohistochemistry for neuronal nuclei (NeuN), parvalbumin (PV), calretinin (CR) and neuropeptide Y (NPY) at 21 days after KA. We observed remarkable cell loss in the ipsilateral subiculum shortly after SE, reflected in lowered density of NeuN+ cells in the chronic stage when epileptic activity occurred in the subiculum concomitantly with the hippocampus. In addition, we show a position-dependent reduction of Gad67-expressing INs by ∼50% (along the dorso-ventral as well as transverse axis of the subiculum). This particularly affected the PV- and to a lesser extent CR-expressing INs. The density of NPY-positive neurons was increased, but the double-labeling for Gad67 mRNA expression revealed that an upregulation or de novo expression of NPY in non-GABAergic cells with a concomitant reduction of NPY-positive INs underlies this observation. Our data suggest a position- and cell type-specific vulnerability of subicular INs in MTLE, which might contribute to hyperexcitability of the subiculum, reflected in epileptic activity.
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Affiliation(s)
- Julia Franz
- Experimental Epilepsy Research, Department of Neurosurgery, Faculty of Medicine, Medical Center-University of Freiburg, Freiburg, Germany
| | - Nicole Barheier
- Experimental Epilepsy Research, Department of Neurosurgery, Faculty of Medicine, Medical Center-University of Freiburg, Freiburg, Germany
- Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Henrike Wilms
- Experimental Epilepsy Research, Department of Neurosurgery, Faculty of Medicine, Medical Center-University of Freiburg, Freiburg, Germany
| | - Susanne Tulke
- Experimental Epilepsy Research, Department of Neurosurgery, Faculty of Medicine, Medical Center-University of Freiburg, Freiburg, Germany
| | - Carola A. Haas
- Experimental Epilepsy Research, Department of Neurosurgery, Faculty of Medicine, Medical Center-University of Freiburg, Freiburg, Germany
- Center for Basics in NeuroModulation, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- BrainLinks-BrainTools, University of Freiburg, Freiburg, Germany
| | - Ute Häussler
- Experimental Epilepsy Research, Department of Neurosurgery, Faculty of Medicine, Medical Center-University of Freiburg, Freiburg, Germany
- BrainLinks-BrainTools, University of Freiburg, Freiburg, Germany
- *Correspondence: Ute Häussler,
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Kilias A, Tulke S, Barheier N, Ruther P, Häussler U. Integration of the CA2 region in the hippocampal network during epileptogenesis. Hippocampus 2023; 33:223-240. [PMID: 36421040 DOI: 10.1002/hipo.23479] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 10/14/2022] [Accepted: 11/02/2022] [Indexed: 11/26/2022]
Abstract
The CA2 pyramidal cells are mostly resistant to cell death in mesial temporal lobe epilepsy (MTLE) with hippocampal sclerosis, but they are aberrantly integrated into the epileptic hippocampal network via mossy fiber sprouting. Furthermore, they show increased excitability in vitro in hippocampal slices obtained from human MTLE specimens or animal epilepsy models. Although these changes promote CA2 to contribute to epileptic activity (EA) in vivo, the role of CA2 in the epileptic network within and beyond the sclerotic hippocampus is still unclear. We used the intrahippocampal kainate mouse model for MTLE, which recapitulates most features of the human disease including pharmacoresistant epileptic seizures and hippocampal sclerosis, with preservation of dentate gyrus (DG) granule cells and CA2 pyramidal cells. In vivo recordings with electrodes in CA2 and the DG showed that EA occurs at high coincidence between the ipsilateral DG and CA2 and current source density analysis of silicon probe recordings in dorsal ipsilateral CA2 revealed CA2 as a local source of EA. Cell-specific viral tracing in Amigo2-icreERT2 mice confirmed the preservation of the axonal projection from ipsilateral CA2 pyramidal cells to contralateral CA2 under epileptic conditions and indeed, EA propagated from ipsi- to contralateral CA2 with increasing likelihood with time after KA injection, but always at lower intensity than within the ipsilateral hippocampus. Furthermore, we show that CA2 presents with local theta oscillations and like the DG, shows a pathological reduction of theta frequency already from 2 days after KA onward. The early changes in activity might be facilitated by the loss of glutamic acid decarboxylase 67 (Gad67) mRNA-expressing interneurons directly after the initial status epilepticus in ipsi- but not contralateral CA2. Together, our data highlight CA2 as an active player in the epileptic network and with its contralateral connections as one possible router of aberrant activity.
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Affiliation(s)
- Antje Kilias
- Institute for Physiology I, Medical Faculty, University of Freiburg, Freiburg, Germany
| | - Susanne Tulke
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany
| | - Nicole Barheier
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Patrick Ruther
- Microsystem Materials Laboratory, Department of Microsystems Engineering (IMTEK), University of Freiburg, Freiburg, Germany.,Center BrainLinks-BrainTools, University of Freiburg, Freiburg, Germany
| | - Ute Häussler
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany.,Center BrainLinks-BrainTools, University of Freiburg, Freiburg, Germany
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Kleis P, Paschen E, Häussler U, Bernal Sierra YA, Haas CA. Long-term in vivo application of a potassium channel-based optogenetic silencer in the healthy and epileptic mouse hippocampus. BMC Biol 2022; 20:18. [PMID: 35031048 PMCID: PMC8760681 DOI: 10.1186/s12915-021-01210-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 12/07/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Optogenetic tools allow precise manipulation of neuronal activity via genetically encoded light-sensitive proteins. Currently available optogenetic inhibitors are not suitable for prolonged use due to short-lasting photocurrents, tissue heating, and unintended changes in ion distributions, which may interfere with normal neuron physiology. To overcome these limitations, a novel potassium channel-based optogenetic silencer, named PACK, was recently developed. The PACK tool has two components: a photoactivated adenylyl cyclase from Beggiatoa (bPAC) and a cAMP-dependent potassium channel, SthK, which carries a large, long-lasting potassium current in mammalian cells. Previously, it has been shown that activating the PACK silencer with short light pulses led to a significant reduction of neuronal firing in various in vitro and acute in vivo settings. Here, we examined the viability of performing long-term studies in vivo by looking at the inhibitory action and side effects of PACK and its components in healthy and epileptic adult male mice. RESULTS We targeted hippocampal cornu ammonis (CA1) pyramidal cells using a viral vector and enabled illumination of these neurons via an implanted optic fiber. Local field potential (LFP) recordings from CA1 of freely moving mice revealed significantly reduced neuronal activity during 50-min intermittent (0.1 Hz) illumination, especially in the gamma frequency range. Adversely, PACK expression in healthy mice induced chronic astrogliosis, dispersion of pyramidal cells, and generalized seizures. These side effects were independent of the light application and were also present in mice expressing bPAC without the potassium channel. Light activation of bPAC alone increased neuronal activity, presumably via enhanced cAMP signaling. Furthermore, we applied bPAC and PACK in the contralateral hippocampus of chronically epileptic mice following a unilateral injection of intrahippocampal kainate. Unexpectedly, the expression of bPAC in the contralateral CA1 area was sufficient to prevent the spread of spontaneous epileptiform activity from the seizure focus to the contralateral hippocampus. CONCLUSION Our study highlights the PACK tool as a potent optogenetic inhibitor in vivo. However, further refinement of its light-sensitive domain is required to avoid unexpected physiological changes.
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Affiliation(s)
- P Kleis
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, 79106, Freiburg, Germany
| | - E Paschen
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, 79106, Freiburg, Germany.,Faculty of Biology, University of Freiburg, 79104, Freiburg, Germany
| | - U Häussler
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, 79106, Freiburg, Germany.,BrainLinks-BrainTools, University of Freiburg, 79110, Freiburg, Germany
| | - Y A Bernal Sierra
- Experimental Biophysics, Institute of Biology, Humboldt University of Berlin, 10115, Berlin, Germany
| | - C A Haas
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, 79106, Freiburg, Germany. .,BrainLinks-BrainTools, University of Freiburg, 79110, Freiburg, Germany. .,Center for Basics in NeuroModulation, Faculty of Medicine, University of Freiburg, 79106, Freiburg, Germany.
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Freiman TM, Häussler U, Zentner J, Doostkam S, Beck J, Scheiwe C, Brandt A, Haas CA, Puhahn-Schmeiser B. Mossy fiber sprouting into the hippocampal region CA2 in patients with temporal lobe epilepsy. Hippocampus 2021; 31:580-592. [PMID: 33720466 DOI: 10.1002/hipo.23323] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 02/23/2021] [Accepted: 02/27/2021] [Indexed: 01/28/2023]
Abstract
Hippocampal sclerosis (HS) in Temporal Lobe Epilepsy (TLE) shows neuronal death in cornu ammonis (CA)1, CA3, and CA4. It is known that granule cells and CA2 neurons survive and their axons, the mossy fibers (MF), lose their target cells in CA3 and CA4 and sprout to the granule cell layer and molecular layer. We examined in TLE patients and in a mouse epilepsy model, whether MF sprouting is directed to the dentate gyrus or extends to distant CA regions and whether sprouting is associated with death of target neurons in CA3 and CA4. In 319 TLE patients, HS was evaluated by Wyler grade and International League against Epilepsy (ILAE) types using immunohistochemistry against neuronal nuclei (NeuN). Synaptoporin was used to colocalize MF. In addition, transgenic Thy1-eGFP mice were intrahippocampally injected with kainate and sprouting of eGFP-positive MFs was analyzed together with immunocytochemistry for regulator of G-protein signaling 14 (RGS14). In human HS Wyler III and IV as well as in ILAE 1, 2, and 3 specimens, we found synaptoporin-positive axon terminals in CA2 and even in CA1, associated with the extent of granule cell dispersion. Sprouting was seen in cases with cell death of target neurons in CA3 and CA4 (classical severe HS ILAE type 1) but also without this cell death (atypical HS ILAE type 2). Similarly, in epileptic mice eGFP-positive MFs sprouted to CA2 and beyond. The presence of MF terminals in the CA2 pyramidal cell layer and in CA1 was also correlated with the extent of granule cell dispersion. The similarity of our findings in human specimens and in the mouse model highlights the importance and opens up new chances of using translational approaches to determine mechanisms underlying TLE.
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Affiliation(s)
- Thomas M Freiman
- Department of Neurosurgery, Rostock University Medical Center, Rostock, Germany
| | - Ute Häussler
- Department of Neurosurgery, Experimental Epilepsy Research, Medical Center-University of Freiburg, Faculty of Medicine, Freiburg, Germany.,Faculty of Medicine, Center for Basics in NeuroModulation, University of Freiburg, Freiburg, Germany.,BrainLinks-BrainTools Center, University of Freiburg, Freiburg, Germany
| | - Josef Zentner
- Faculty of Medicine, Department of Neurosurgery, Medical Center-University of Freiburg, Freiburg, Germany
| | - Soroush Doostkam
- Faculty of Medicine, Institute of Neuropathology, Medical Center-University of Freiburg, Freiburg, Germany
| | - Jürgen Beck
- Faculty of Medicine, Department of Neurosurgery, Medical Center-University of Freiburg, Freiburg, Germany
| | - Christian Scheiwe
- Faculty of Medicine, Department of Neurosurgery, Medical Center-University of Freiburg, Freiburg, Germany
| | - Armin Brandt
- Epilepsy Center, University Medical Center, Albert-Ludwigs-University, Freiburg, Germany
| | - Carola A Haas
- Department of Neurosurgery, Experimental Epilepsy Research, Medical Center-University of Freiburg, Faculty of Medicine, Freiburg, Germany.,Faculty of Medicine, Center for Basics in NeuroModulation, University of Freiburg, Freiburg, Germany.,BrainLinks-BrainTools Center, University of Freiburg, Freiburg, Germany
| | - Barbara Puhahn-Schmeiser
- Faculty of Medicine, Department of Neurosurgery, Medical Center-University of Freiburg, Freiburg, Germany
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Paschen E, Elgueta C, Heining K, Vieira DM, Kleis P, Orcinha C, Häussler U, Bartos M, Egert U, Janz P, Haas CA. Hippocampal low-frequency stimulation prevents seizure generation in a mouse model of mesial temporal lobe epilepsy. eLife 2020; 9:54518. [PMID: 33349333 PMCID: PMC7800381 DOI: 10.7554/elife.54518] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 12/13/2020] [Indexed: 12/18/2022] Open
Abstract
Mesial temporal lobe epilepsy (MTLE) is the most common form of focal, pharmacoresistant epilepsy in adults and is often associated with hippocampal sclerosis. Here, we established the efficacy of optogenetic and electrical low-frequency stimulation (LFS) in interfering with seizure generation in a mouse model of MTLE. Specifically, we applied LFS in the sclerotic hippocampus to study the effects on spontaneous subclinical and evoked generalized seizures. We found that stimulation at 1 Hz for 1 hr resulted in an almost complete suppression of spontaneous seizures in both hippocampi. This seizure-suppressive action during daily stimulation remained stable over several weeks. Furthermore, LFS for 30 min before a pro-convulsive stimulus successfully prevented seizure generalization. Finally, acute slice experiments revealed a reduced efficacy of perforant path transmission onto granule cells upon LFS. Taken together, our results suggest that hippocampal LFS constitutes a promising approach for seizure control in MTLE.
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Affiliation(s)
- Enya Paschen
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Claudio Elgueta
- Systemic and Cellular Neurophysiology, Institute for Physiology I, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Katharina Heining
- Biomicrotechnology, Department of Microsystems Engineering - IMTEK, Faculty of Engineering, University of Freiburg, Freiburg, Germany.,Bernstein Center Freiburg, University of Freiburg, Freiburg, Germany
| | - Diego M Vieira
- Biomicrotechnology, Department of Microsystems Engineering - IMTEK, Faculty of Engineering, University of Freiburg, Freiburg, Germany.,Bernstein Center Freiburg, University of Freiburg, Freiburg, Germany
| | - Piret Kleis
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany
| | - Catarina Orcinha
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany
| | - Ute Häussler
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany.,Center for Basics in NeuroModulation, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Marlene Bartos
- Systemic and Cellular Neurophysiology, Institute for Physiology I, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Center for Basics in NeuroModulation, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Ulrich Egert
- Biomicrotechnology, Department of Microsystems Engineering - IMTEK, Faculty of Engineering, University of Freiburg, Freiburg, Germany.,Bernstein Center Freiburg, University of Freiburg, Freiburg, Germany
| | - Philipp Janz
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany
| | - Carola A Haas
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany.,Bernstein Center Freiburg, University of Freiburg, Freiburg, Germany.,Center for Basics in NeuroModulation, Faculty of Medicine, University of Freiburg, Freiburg, Germany
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