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Wallis GJ, Bell LA, Wagner JN, Buxton L, Balachandar L, Wilcox KS. Reactive microglia fail to respond to environmental damage signals in a viral-induced mouse model of temporal lobe epilepsy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.06.583768. [PMID: 38558969 PMCID: PMC10979929 DOI: 10.1101/2024.03.06.583768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Microglia are highly adaptable innate immune cells that rapidly respond to damage signals in the brain through adoption of a reactive phenotype and production of defensive inflammatory cytokines. Microglia express a distinct transcriptome, encoding receptors that allow them to dynamically respond to pathogens, damage signals, and cellular debris. Expression of one such receptor, the microglia-specific purinergic receptor P2ry12, is known to be downregulated in reactive microglia. Here, we explore the microglial response to purinergic damage signals in reactive microglia in the TMEV mouse model of viral brain infection and temporal lobe epilepsy. Using two-photon calcium imaging in acute hippocampal brain slices, we found that the ability of microglia to detect damage signals, engage calcium signaling pathways, and chemoattract towards laser-induced tissue damage was dramatically reduced during the peak period of seizures, cytokine production, and infection. Using combined RNAscope in situ hybridization and immunohistochemistry, we found that during this same stage of heightened infection and seizures, microglial P2ry12 expression was reduced, while the pro-inflammatory cytokine TNF-a expression was upregulated in microglia, suggesting that the depressed ability of microglia to respond to new damage signals via P2ry12 occurs during the time when local elevated cytokine production contributes to seizure generation following infection. Therefore, changes in microglial purinergic receptors during infection likely limit the ability of reactive microglia to respond to new threats in the CNS and locally contain the scale of the innate immune response in the brain.
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Affiliation(s)
- Glenna J Wallis
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT 80904
| | - Laura A Bell
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT 80904
- Interdepartmental Program in Neuroscience, University of Utah, Salt Lake City, UT, 80904
| | - John N Wagner
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT 80904
| | - Lauren Buxton
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT 80904
| | - Lakshmini Balachandar
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT 80904
| | - Karen S Wilcox
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT 80904
- Interdepartmental Program in Neuroscience, University of Utah, Salt Lake City, UT, 80904
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Sun B, Yao J, Chen AW, Estillore JP, Wang R, Back TG, Chen SRW. Genetically and pharmacologically limiting RyR2 open time prevents neuronal hyperactivity of hippocampal CA1 neurons in brain slices of 5xFAD mice. Neurosci Lett 2021; 758:136011. [PMID: 34090936 DOI: 10.1016/j.neulet.2021.136011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 03/19/2021] [Accepted: 05/28/2021] [Indexed: 12/11/2022]
Abstract
Neuronal hyperactivity is an early, common manifestation of Alzheimer's disease (AD), and is believed to drive AD progression. Neuronal hyperactivity in the form of baseline activity (or spontaneous Ca2+ transients) has consistently been demonstrated in mouse models of AD using two-photon in vivo Ca2+ imaging of cortical or hippocampal neurons in anesthetized animals. Notably, these AD-related spontaneous Ca2+ transients were hardly detected in acute hippocampal slices, probably due to neuronal damage during brain slicing. To better preserve neuronal activity, we employed the N-methyl-D-glucamine (NMDG) protective brain slicing protocol. We performed confocal in vitro Ca2+ imaging of hippocampal CA1 neurons in optimized hippocampal slices. Consistent with previous in vivo studies, our in vitro studies using optimized brain slices also showed that limiting the open duration of the ryanodine receptor 2 (RyR2) by the RyR2 mutation E4872Q or by the R-carvedilol enantiomer prevented and rescued neuronal hyperactivity of hippocampal CA1 neurons from 5xFAD mice. Thus, genetically and pharmacologically limiting RyR2 open time prevented and rescued AD-related neuronal hyperactivity in vitro in optimized brain slices in the absence of anesthetics' influence. Our data also suggest that the NMDG protective brain slicing preparation offers an alternative means to study neuronal hyperactivity of various cell types in different brain regions, especially in regions that are not readily accessible to two-photon in vivo Ca2+ imaging.
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Affiliation(s)
- Bo Sun
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada
| | - Jinjing Yao
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada
| | - Alexander W Chen
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada
| | - John Paul Estillore
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada
| | - Ruiwu Wang
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada
| | - Thomas G Back
- Department of Chemistry, University of Calgary, Calgary, AB, Canada
| | - S R Wayne Chen
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.
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Yao J, Sun B, Institoris A, Zhan X, Guo W, Song Z, Liu Y, Hiess F, Boyce AKJ, Ni M, Wang R, Ter Keurs H, Back TG, Fill M, Thompson RJ, Turner RW, Gordon GR, Chen SRW. Limiting RyR2 Open Time Prevents Alzheimer's Disease-Related Neuronal Hyperactivity and Memory Loss but Not β-Amyloid Accumulation. Cell Rep 2021; 32:108169. [PMID: 32966798 PMCID: PMC7532726 DOI: 10.1016/j.celrep.2020.108169] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 07/23/2020] [Accepted: 08/27/2020] [Indexed: 12/31/2022] Open
Abstract
Neuronal hyperactivity is an early primary dysfunction in Alzheimer’s disease (AD) in humans and animal models, but effective neuronal hyperactivity-directed anti-AD therapeutic agents are lacking. Here we define a previously unknown mode of ryanodine receptor 2 (RyR2) control of neuronal hyperactivity and AD progression. We show that a single RyR2 point mutation, E4872Q, which reduces RyR2 open time, prevents hyperexcitability, hyperactivity, memory impairment, neuronal cell death, and dendritic spine loss in a severe early-onset AD mouse model (5xFAD). The RyR2-E4872Q mutation upregulates hippocampal CA1-pyramidal cell A-type K+ current, a well-known neuronal excitability control that is downregulated in AD. Pharmacologically limiting RyR2 open time with the R-carvedilol enantiomer (but not racemic carvedilol) prevents and rescues neuronal hyperactivity, memory impairment, and neuron loss even in late stages of AD. These AD-related deficits are prevented even with continued β-amyloid accumulation. Thus, limiting RyR2 open time may be a hyperactivity-directed, non-β-amyloid-targeted anti-AD strategy. Yao et al. show that genetically or pharmacologically limiting the open duration of ryanodine receptor 2 upregulates the A-type potassium current and prevents neuronal hyperexcitability and hyperactivity, memory impairment, neuronal cell death, and dendritic spine loss in a severe early-onset Alzheimer’s disease mouse model, even with continued accumulation of β-amyloid.
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Affiliation(s)
- Jinjing Yao
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Bo Sun
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada; Medical School, Kunming University of Science and Technology, Kunming 650504, China
| | - Adam Institoris
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Xiaoqin Zhan
- Hotchkiss Brain Institute, Department of Cell Biology and Anatomy, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Wenting Guo
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Zhenpeng Song
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Yajing Liu
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Florian Hiess
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Andrew K J Boyce
- Hotchkiss Brain Institute, Department of Cell Biology and Anatomy, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Mingke Ni
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Ruiwu Wang
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Henk Ter Keurs
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Thomas G Back
- Department of Chemistry, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Michael Fill
- Department of Physiology & Biophysics, Rush University Medical Center, Chicago, IL 60612, USA
| | - Roger J Thompson
- Hotchkiss Brain Institute, Department of Cell Biology and Anatomy, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Ray W Turner
- Hotchkiss Brain Institute, Department of Cell Biology and Anatomy, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Grant R Gordon
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - S R Wayne Chen
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada; Department of Physiology & Biophysics, Rush University Medical Center, Chicago, IL 60612, USA.
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Tvrdik P, Kalani MYS. In Vivo Imaging of Microglial Calcium Signaling in Brain Inflammation and Injury. Int J Mol Sci 2017; 18:ijms18112366. [PMID: 29117112 PMCID: PMC5713335 DOI: 10.3390/ijms18112366] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Revised: 11/01/2017] [Accepted: 11/04/2017] [Indexed: 12/20/2022] Open
Abstract
Microglia, the innate immune sentinels of the central nervous system, are the most dynamic cells in the brain parenchyma. They are the first responders to insult and mediate neuroinflammation. Following cellular damage, microglia extend their processes towards the lesion, modify their morphology, release cytokines and other mediators, and eventually migrate towards the damaged area and remove cellular debris by phagocytosis. Intracellular Ca2+ signaling plays important roles in many of these functions. However, Ca2+ in microglia has not been systematically studied in vivo. Here we review recent findings using genetically encoded Ca2+ indicators and two-photon imaging, which have enabled new insights into Ca2+ dynamics and signaling pathways in large populations of microglia in vivo. These new approaches will help to evaluate pre-clinical interventions and immunomodulation for pathological brain conditions such as stroke and neurodegenerative diseases.
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Affiliation(s)
- Petr Tvrdik
- Department of Neurosurgery, University of Utah School of Medicine, Salt Lake City, UT 84132, USA.
| | - M Yashar S Kalani
- Department of Neurosurgery, University of Virginia School of Medicine, Charlottesville, VA 22908, USA.
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Fadl NN, Ahmed HH, Booles HF, Sayed AH. Serrapeptase and nattokinase intervention for relieving Alzheimer's disease pathophysiology in rat model. Hum Exp Toxicol 2014; 32:721-35. [PMID: 23821590 DOI: 10.1177/0960327112467040] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Serrapeptase (SP) and nattokinase (NK) are proteolytic enzymes belonging to serine proteases. In this study, we hypothesized that SP and NK could modulate certain factors that are associated with Alzheimer's disease (AD) pathophysiology in the experimental model. Oral administration of aluminium chloride (AlCl3) in a dose of 17 mg/kg body weight (bw) daily for 45 days induced AD-like pathology in male rats with a significant increase in brain acetylcholinesterase (AchE) activity, transforming growth factor β (TGF-β), Fas and interleukin-6 (IL-6) levels. Meanwhile, AlCl3 supplementation produced significant decrease in brain-derived neurotrophic factor (BDNF) and insulin-like growth factor-1 (IGF-1) when compared with control values. Also, AlCl3 administration caused significant decline in the expression levels of disintegrin and metalloproteinase domain 9 (ADAM9) and a disintegrin and metalloproteinase domain 10 (ADAM10) genes in the brain. Histological investigation of brain tissue of rat model of AD showed neuronal degeneration in the hippocampus and focal hyalinosis with cellular as well as a cellular amyloid plaques formation. Oral administration of SP or NK in a rat model of AD daily for 45 days resulted in a significant decrease in brain AchE activity, TGF-β, Fas and IL-6 levels. Also, the treatment with these enzymes produced significant increase in BDNF and IGF-1 levels when compared with the untreated AD-induced rats. Moreover, both SP and NK could markedly increase the expression levels of ADAM9 and ADAM10 genes in the brain tissue of the treated rats. These findings were well confirmed by the histological examination of the brain tissue of the treated rats. The present results support our hypothesis that the oral administration of proteolytitc enzymes, SP and/or NK, would have an effective role in modulating certain factors characterizing AD. Thus, these enzymes may have a therapeutic application in the treatment of AD.
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Affiliation(s)
- N N Fadl
- Medical Physiology Department, National Research Centre, Dokki, Cairo, Egypt
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