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Zhang Z, Ishrat S, O'Bryan M, Klein B, Saraswati M, Robertson C, Kannan S. Pediatric Traumatic Brain Injury Causes Long-Term Deficits in Adult Hippocampal Neurogenesis and Cognition. J Neurotrauma 2020; 37:1656-1667. [DOI: 10.1089/neu.2019.6894] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Affiliation(s)
- Zhi Zhang
- Department of Natural Sciences, University of Michigan-Dearborn, Dearborn, Michigan, USA
| | - Samiha Ishrat
- Department of Natural Sciences, University of Michigan-Dearborn, Dearborn, Michigan, USA
| | - Megan O'Bryan
- Department of Natural Sciences, University of Michigan-Dearborn, Dearborn, Michigan, USA
| | - Brandon Klein
- Department of Natural Sciences, University of Michigan-Dearborn, Dearborn, Michigan, USA
| | - Manda Saraswati
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland, USA
| | - Courtney Robertson
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland, USA
| | - Sujatha Kannan
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland, USA
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Victor TR, Tsirka SE. Microglial contributions to aberrant neurogenesis and pathophysiology of epilepsy. NEUROIMMUNOLOGY AND NEUROINFLAMMATION 2020; 7:234-247. [PMID: 33154976 PMCID: PMC7641338 DOI: 10.20517/2347-8659.2020.02] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Microglia are dynamic cells that constitute the brain's innate immune system. Recently, research has demonstrated microglial roles beyond immunity, which include homeostatic roles in the central nervous system. The function of microglia is an active area of study, with insights into changes in neurogenesis and synaptic pruning being discovered in both health and disease. In epilepsy, activated microglia contribute to several changes that occur during epileptogenesis. In this review, we focus on the effects of microglia on neurogenesis and synaptic pruning, and discuss the current state of anti-seizure drugs and how they affect microglia during these processes. Our understanding of the role of microglia post-seizure is still limited and may be pivotal in recognizing new therapeutic targets for seizure intervention.
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Affiliation(s)
- Tanya R Victor
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, NY 11794, USA
| | - Stella E Tsirka
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, NY 11794, USA
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Matsuda T, Nakashima K. Natural and forced neurogenesis in the adult brain: Mechanisms and their possible application to treat neurological disorders. Neurosci Res 2020; 166:1-11. [PMID: 32497571 DOI: 10.1016/j.neures.2020.05.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 05/18/2020] [Accepted: 05/19/2020] [Indexed: 01/17/2023]
Abstract
Neural stem cells (NSCs) in the adult hippocampus generate new neurons via a process referred to as neurogenesis, supporting cognitive functions. Since altered neurogenesis has been reportedly associated with several diseases such as epilepsy, the molecular basis of NSC activity is an important focus in the study of neurogenesis. Furthermore, facilitation of neurogenesis in the injured brain would be an ideal approach to replenish lost neurons for damage recovery. However, natural neurogenesis by endogenous NSCs in the adult brain is insufficient for complete recovery after severe injury. Recent advances in understanding forced neurogenesis from brain-resident non-neuronal cells by direct reprogramming and clearing hurdles to achieve it have improved the ability to replace damaged neurons in the brain. In this review, we describe molecular mechanisms underlying natural and forced neurogenesis, and discuss future directions for treatments of diseases in the central nervous system.
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Affiliation(s)
- Taito Matsuda
- Department of Stem Cell Biology and Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
| | - Kinichi Nakashima
- Department of Stem Cell Biology and Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
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Endonuclease VIII-like 1 deficiency impairs survival of newly generated hippocampal neurons and memory performance in young-adult male mice. Life Sci 2020; 254:117755. [PMID: 32437792 DOI: 10.1016/j.lfs.2020.117755] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 04/29/2020] [Accepted: 05/04/2020] [Indexed: 11/20/2022]
Abstract
AIMS Efficient memory formation in rodents depends on adult neurogenesis in the subgranular zone of the hippocampus, and mounting evidence suggests that deficiencies in initiating repair of oxidatively induced DNA damage may impair neurogenesis. Hence, we aimed to determine whether loss of the DNA glycosylase, endonuclease VIII-like 1 (Neil1), affects hippocampal neurogenesis and memory performance in young-adult mice. MAIN METHODS Eight-week-old male wild-type and Neil1-deficient (Neil1-/-) mice were treated with bromodeoxyuridine to track neuronal proliferation and differentiation. A neurosphere formation assay was further used to measure neuroprogenitor proliferative capacity. Hippocampus-related memory functions were assessed with Y-maze spontaneous alternation and novel object recognition tests. KEY FINDINGS Young-adult male Neil1-/- mice exhibited diminished adult hippocampal neurogenesis in the dentate gyrus, probably as a result of poor survival of newly proliferated neurons. Furthermore, the Y-maze spontaneous alternation and novel object recognition tests respectively revealed that Neil1 deficiency impairs spatial and non-spatial hippocampus-related memory functions. We also found that expression of p53, a central regulator of apoptosis, was upregulated in the dentate gyrus of Neil1-/- mice, while the level of β-catenin, a key cell survival molecule, was downregulated. SIGNIFICANCE The DNA glycosylase, Neil1, promotes successful hippocampal neurogenesis and learning and memory in young-adult mice.
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Yamanaka G, Morichi S, Takamatsu T, Takahashi R, Watanabe Y, Ishida Y, Takeshita M, Morishita N, Kasuga A, Kanou K, Oana S, Suzuki S, Go S, Kashiwagi Y, Kawashima H. Granzyme A Participates in the Pathogenesis of Infection-Associated Acute Encephalopathy. J Child Neurol 2020; 35:208-214. [PMID: 31709864 DOI: 10.1177/0883073819886217] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
OBJECTIVE The present study aimed to determine whether granzymes are implicated in the pathogenesis of infection-associated acute encephalopathy (AE). METHODS We investigated granzyme and cytokine levels in the cerebrospinal fluid of patients with acute encephalopathy or complex febrile seizures (cFS). A total of 24 acute encephalopathy patients and 22 complex febrile seizures patients were included in the present study. Levels of granzymes A and B were measured using enzyme-linked immunosorbent assay, and levels of tumor necrosis factor α (TNF-α), interferon-γ (IFN-γ), interleukin 1β (IL-1β), IL-1 receptor antagonist (IL-1RA), IL-4, IL-6, IL-8, and IL-10 were assessed using the Bio-Plex suspension array system. RESULTS Cerebrospinal fluid levels of granzyme A were significantly higher, and those of TNF-α and IL-1RA were significantly lower in the AE group than in the cFS group; however, no significant differences in the levels of granzyme B, IFN-γ, IL-1β, IL-4, IL-6, IL-8, and IL-10 were observed between the 2 groups. In addition, no significant differences in granzyme A, granzyme B, or cytokine levels were observed between acute encephalopathy patients with and those without neurologic sequelae. CONCLUSIONS Our findings indicate the involvement of granzyme A in the pathogenesis of acute encephalopathy.
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Affiliation(s)
- Gaku Yamanaka
- Department of Pediatrics and Adolescent Medicine, Tokyo Medical University, Shinjuku, Tokyo, Japan
| | - Shinichiro Morichi
- Department of Pediatrics and Adolescent Medicine, Tokyo Medical University, Shinjuku, Tokyo, Japan
| | - Tomoko Takamatsu
- Department of Pediatrics and Adolescent Medicine, Tokyo Medical University, Shinjuku, Tokyo, Japan
| | - Ryou Takahashi
- Department of Pediatrics and Adolescent Medicine, Tokyo Medical University, Shinjuku, Tokyo, Japan
| | - Yusuke Watanabe
- Department of Pediatrics and Adolescent Medicine, Tokyo Medical University, Shinjuku, Tokyo, Japan
| | - Yu Ishida
- Department of Pediatrics and Adolescent Medicine, Tokyo Medical University, Shinjuku, Tokyo, Japan
| | - Mika Takeshita
- Department of Pediatrics and Adolescent Medicine, Tokyo Medical University, Shinjuku, Tokyo, Japan
| | - Natsumi Morishita
- Department of Pediatrics and Adolescent Medicine, Tokyo Medical University, Shinjuku, Tokyo, Japan
| | - Akiko Kasuga
- Department of Pediatrics and Adolescent Medicine, Tokyo Medical University, Shinjuku, Tokyo, Japan
| | - Kanako Kanou
- Department of Pediatrics and Adolescent Medicine, Tokyo Medical University, Shinjuku, Tokyo, Japan
| | - Singo Oana
- Department of Pediatrics and Adolescent Medicine, Tokyo Medical University, Shinjuku, Tokyo, Japan
| | - Shunsuke Suzuki
- Department of Pediatrics and Adolescent Medicine, Tokyo Medical University, Shinjuku, Tokyo, Japan
| | - Soken Go
- Department of Pediatrics and Adolescent Medicine, Tokyo Medical University, Shinjuku, Tokyo, Japan
| | - Yasuyo Kashiwagi
- Department of Pediatrics and Adolescent Medicine, Tokyo Medical University, Shinjuku, Tokyo, Japan
| | - Hisashi Kawashima
- Department of Pediatrics and Adolescent Medicine, Tokyo Medical University, Shinjuku, Tokyo, Japan
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Mazzolini J, Le Clerc S, Morisse G, Coulonges C, Kuil LE, van Ham TJ, Zagury J, Sieger D. Gene expression profiling reveals a conserved microglia signature in larval zebrafish. Glia 2020; 68:298-315. [PMID: 31508850 PMCID: PMC6916425 DOI: 10.1002/glia.23717] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 08/21/2019] [Accepted: 08/22/2019] [Indexed: 12/23/2022]
Abstract
Microglia are the resident macrophages of the brain. Over the past decade, our understanding of the function of these cells has significantly improved. Microglia do not only play important roles in the healthy brain but are involved in almost every brain pathology. Gene expression profiling allowed to distinguish microglia from other macrophages and revealed that the full microglia signature can only be observed in vivo. Thus, animal models are irreplaceable to understand the function of these cells. One of the popular models to study microglia is the zebrafish larva. Due to their optical transparency and genetic accessibility, zebrafish larvae have been employed to understand a variety of microglia functions in the living brain. Here, we performed RNA sequencing of larval zebrafish microglia at different developmental time points: 3, 5, and 7 days post fertilization (dpf). Our analysis reveals that larval zebrafish microglia rapidly acquire the core microglia signature and many typical microglia genes are expressed from 3 dpf onwards. The majority of changes in gene expression happened between 3 and 5 dpf, suggesting that differentiation mainly takes place during these days. Furthermore, we compared the larval microglia transcriptome to published data sets of adult zebrafish microglia, mouse microglia, and human microglia. Larval microglia shared a significant number of expressed genes with their adult counterparts in zebrafish as well as with mouse and human microglia. In conclusion, our results show that larval zebrafish microglia mature rapidly and express the core microglia gene signature that seems to be conserved across species.
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Affiliation(s)
- Julie Mazzolini
- Centre for Discovery Brain SciencesUniversity of EdinburghEdinburghUK
| | - Sigrid Le Clerc
- Laboratoire GBCM, EA7528, Conservatoire National des Arts et MétiersHESAM UniversitéParisFrance
| | - Gregoire Morisse
- Centre for Discovery Brain SciencesUniversity of EdinburghEdinburghUK
| | - Cédric Coulonges
- Laboratoire GBCM, EA7528, Conservatoire National des Arts et MétiersHESAM UniversitéParisFrance
| | - Laura E. Kuil
- Department of Clinical Genetics, Erasmus MCUniversity Medical Center RotterdamRotterdamThe Netherlands
| | - Tjakko J. van Ham
- Department of Clinical Genetics, Erasmus MCUniversity Medical Center RotterdamRotterdamThe Netherlands
| | - Jean‐François Zagury
- Laboratoire GBCM, EA7528, Conservatoire National des Arts et MétiersHESAM UniversitéParisFrance
| | - Dirk Sieger
- Centre for Discovery Brain SciencesUniversity of EdinburghEdinburghUK
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Synaptic Pruning by Microglia in Epilepsy. J Clin Med 2019; 8:jcm8122170. [PMID: 31818018 PMCID: PMC6947403 DOI: 10.3390/jcm8122170] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Revised: 11/27/2019] [Accepted: 12/05/2019] [Indexed: 12/16/2022] Open
Abstract
Structural and functional collapse of the balance between excitatory (E) and inhibitory (I) synapses, i.e., synaptic E/I balance, underlies the pathogeneses of various central nervous system (CNS) disorders. In epilepsy, the synaptic E/I balance tips toward excitation; thus, most of the existing epileptic remedies have focused on how to directly suppress the activity of neurons. However, because as many as 30% of patients with epilepsy are drug resistant, the discovery of new therapeutic targets is strongly desired. Recently, the roles of glial cells in epilepsy have gained attention because glial cells manipulate synaptic structures and functions in addition to supporting neuronal survival and growth. Among glial cells, microglia, which are brain-resident immune cells, have been shown to mediate inflammation, neuronal death and aberrant neurogenesis after epileptic seizures. However, few studies have investigated the involvement of synaptic pruning—one of the most important roles of microglia—in the epileptic brain. In this review, we propose and discuss the hypothesis that synaptic pruning by microglia is enhanced in the epileptic brain, drawing upon the findings of previous studies. We further discuss the possibility that aberrant synaptic pruning by microglia induces synaptic E/I imbalance, promoting the development and aggravation of epilepsy.
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Microglial P2Y12 Receptor Regulates Seizure-Induced Neurogenesis and Immature Neuronal Projections. J Neurosci 2019; 39:9453-9464. [PMID: 31597724 DOI: 10.1523/jneurosci.0487-19.2019] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2019] [Revised: 10/01/2019] [Accepted: 10/02/2019] [Indexed: 11/21/2022] Open
Abstract
Seizures are common in humans with various etiologies ranging from congenital aberrations to acute injuries that alter the normal balance of brain excitation and inhibition. A notable consequence of seizures is the induction of aberrant neurogenesis and increased immature neuronal projections. However, regulatory mechanisms governing these features during epilepsy development are not fully understood. Recent studies show that microglia, the brain's resident immune cell, contribute to normal neurogenesis and regulate seizure phenotypes. However, the role of microglia in aberrant neurogenic seizure contexts has not been adequately investigated. To address this question, we coupled the intracerebroventricular kainic acid model with current pharmacogenetic approaches to eliminate microglia in male mice. We show that microglia promote seizure-induced neurogenesis and subsequent seizure-induced immature neuronal projections above and below the pyramidal neurons between the DG and the CA3 regions. Furthermore, we identify microglial P2Y12 receptors (P2Y12R) as a participant in this neurogenic process. Together, our results implicate microglial P2Y12R signaling in epileptogenesis and provide further evidence for targeting microglia in general and microglial P2Y12R in specific to ameliorate proepileptogenic processes.SIGNIFICANCE STATEMENT Epileptogenesis is a process by which the brain develops epilepsy. Several processes have been identified that confer the brain with such epileptic characteristics, including aberrant neurogenesis and increased immature neuronal projections. Understanding the mechanisms that promote such changes is critical in developing therapies to adequately restrain epileptogenesis. We investigated the role of purinergic P2Y12 receptors selectively expressed by microglia, the resident brain immune cells. We report, for the first time, that microglia in general and microglial P2Y12 receptors in specific promote both aberrant neurogenesis and increased immature neuronal projections. These results indicate that microglia enhance epileptogenesis by promoting these processes and suggest that targeting this immune axis could be a novel therapeutic strategy in the clinic.
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Manakkat Vijay GK, Hu C, Peng J, Garcia-Martinez I, Hoque R, Verghis RM, Ma Y, Mehal WZ, Shawcross DL, Wen L. Ammonia-Induced Brain Edema Requires Macrophage and T Cell Expression of Toll-Like Receptor 9. Cell Mol Gastroenterol Hepatol 2019; 8:609-623. [PMID: 31401214 PMCID: PMC6889059 DOI: 10.1016/j.jcmgh.2019.08.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 07/31/2019] [Accepted: 08/02/2019] [Indexed: 01/05/2023]
Abstract
BACKGROUND & AIM Ammonia is central in the pathogenesis of brain edema in acute liver failure (ALF) with infection and systemic inflammation expediting development of intracranial hypertension (ICH). Patients with acetaminophen-induced ALF have increased neutrophil TLR9 expression which can be induced by ammonia. We determined whether ammonia-induced brain edema and immune dysfunction are mediated by TLR9 and if this could be prevented in a TLR9-deficient mouse model. METHODS Ammonium acetate (NH4-Ac; 4mmol/kg) was injected intraperitoneally in wild type (WT), Tlr9-/- and Lysm-Cre Tlr9fl/fl mice (TLR9 absent in neutrophils and macrophages including Kupffer cells) and compared to controls. Six hours after NH4-Ac injection, intracellular cytokine production was determined in splenic macrophages, CD4+ and CD8+ T cells. Brain water (BW) and total plasma DNA (tDNA) were also measured. The impact of the TLR9 antagonist ODN2088 (50μg/mouse) was evaluated. RESULTS Following NH4-Ac injection, BW, macrophage and T cell cytokine production increased (P < .0001) in WT but not Tlr9-/- mice (P < .001). ODN2088 inhibited macrophage and T cell cytokine production (P < .05) and prevented an increase in BW (P < .0001). Following NH4-Ac injection, macrophage cytokine production and BW were ameliorated in Lysm-Cre Tlr9fl/fl mice compared to WT mice (P < .05) but there was no difference compared to Tlr9-/- mice. Following NH4-Ac injection, plasma tDNA levels increased in WT and Tlr9-/- mice (P < .05) suggesting that TLR9 may be activated by DNA released from ammonia-stimulated cells. CONCLUSION Ammonia-induced brain edema requires macrophage and T cell expression of TLR9. Amelioration of brain edema and lymphocyte cytokine production by ODN2088 supports exploration of TLR9 antagonism in early ALF to prevent progression to ICH.
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Affiliation(s)
- Godhev Kumar Manakkat Vijay
- Liver Sciences Department, Faculty of Life Sciences and Medicine, King’s College London, London, United Kingdom,Section of Endocrinology, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Changyun Hu
- Section of Endocrinology, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Jian Peng
- Section of Endocrinology, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Irma Garcia-Martinez
- Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Rafaz Hoque
- Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Rejina Mariam Verghis
- Welcome Wolfson Institute of Experimental Medicine, School of Medicine, Dentistry and Biomedical Science, Queens University, Belfast, United Kingdom
| | - Yun Ma
- Liver Sciences Department, Faculty of Life Sciences and Medicine, King’s College London, London, United Kingdom
| | - Wajahat Zafar Mehal
- Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Debbie Lindsay Shawcross
- Liver Sciences Department, Faculty of Life Sciences and Medicine, King’s College London, London, United Kingdom,Correspondence Address correspondence to: Debbie Lindsay Shawcross, BSc, MBBS, PhD, Liver Sciences Department, Faculty of Life Sciences and Medicine, King’s College London, King’s College Hospital Campus, Denmark Hill, London, SE5 9RS United Kingdom. fax: +44 (0)20 3299 3167.
| | - Li Wen
- Section of Endocrinology, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut,Li Wen, MD, PhD, Section of Endocrinology, Department of Internal Medicine, Yale University School of Medicine, PO Box 208020, 333 Cedar Street, New Haven, Connecticut 06520. fax: (203) 737–5558.
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Toll-like receptor 9 antagonism modulates astrocyte function and preserves proximal axons following spinal cord injury. Brain Behav Immun 2019; 80:328-343. [PMID: 30953770 DOI: 10.1016/j.bbi.2019.04.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 03/14/2019] [Accepted: 04/02/2019] [Indexed: 02/07/2023] Open
Abstract
Increasing evidence indicates that innate immune receptors play important, yet controversial, roles in traumatic central nervous system (CNS) injury. Despite many advances, the contributions of toll-like receptors (TLRs) to spinal cord injury (SCI) remain inadequately defined. We previously reported that a toll-like receptor 9 (TLR9) antagonist, oligodeoxynucleotide 2088 (ODN 2088), administered intrathecally, improves the functional and histopathological outcomes of SCI. However, the molecular and cellular changes that occur at the injury epicenter following ODN 2088 treatment are not completely understood. Following traumatic SCI, a glial scar, consisting primarily of proliferating reactive astrocytes, forms at the injury epicenter and assumes both beneficial and detrimental roles. Increased production of chondroitin sulfate proteoglycans (CSPGs) by reactive astrocytes inhibits the regeneration of injured axons. Astrocytes express TLR9, which can be activated by endogenous ligands released by damaged cells. It is not yet known how TLR9 antagonism modifies astrocyte function at the glial scar and how this affects axonal preservation or re-growth following SCI. The present studies were undertaken to address these issues. We report that in female mice sustaining a severe mid-thoracic (T8) contusion injury, the number of proliferating astrocytes in regions rostral and caudal to the lesion border increased significantly by 30- and 24-fold, respectively, compared to uninjured controls. Intrathecal ODN 2088 treatment significantly reduced the number of proliferating astrocytes by 60% in both regions. This effect appeared to be, at least partly, mediated through the direct actions of ODN 2088 on astrocytes, since the antagonist decreased proliferation in pure SC astrocyte cultures by preventing the activation of the Erk/MAPK signaling pathway. In addition, CSPG immunoreactivity at the lesion border was more pronounced in vehicle-treated injured mice compared to uninjured controls and was significantly reduced following administration of ODN 2088 to injured mice. Moreover, ODN 2088 significantly decreased astrocyte migration in an in vitro scratch-wound assay. Anterograde tracing and quantification of corticospinal tract (CST) axons in injured mice, indicated that ODN 2088 preserves proximal axons. Taken together, these findings suggest that ODN 2088 modifies the glial scar and creates a milieu that fosters axonal protection at the injury site.
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61
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Assessment of genetic variant burden in epilepsy-associated brain lesions. Eur J Hum Genet 2019; 27:1738-1744. [PMID: 31358956 DOI: 10.1038/s41431-019-0484-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 06/29/2019] [Accepted: 07/05/2019] [Indexed: 01/31/2023] Open
Abstract
It is challenging to estimate genetic variant burden across different subtypes of epilepsy. Herein, we used a comparative approach to assess the genetic variant burden and genotype-phenotype correlations in four most common brain lesions in patients with drug-resistant focal epilepsy. Targeted sequencing analysis was performed for a panel of 161 genes with a mean coverage of >400×. Lesional tissue was histopathologically reviewed and dissected from hippocampal sclerosis (n = 15), ganglioglioma (n = 16), dysembryoplastic neuroepithelial tumors (n = 8), and focal cortical dysplasia type II (n = 15). Peripheral blood (n = 12) or surgical tissue samples histopathologically classified as lesion-free (n = 42) were available for comparison. Variants were classified as pathogenic or likely pathogenic according to American College of Medical Genetics and Genomics guidelines. Overall, we identified pathogenic and likely pathogenic variants in 25.9% of patients with a mean coverage of 383×. The highest number of pathogenic/likely pathogenic variants was observed in patients with ganglioglioma (43.75%; all somatic) and dysembryoplastic neuroepithelial tumors (37.5%; all somatic), and in 20% of cases with focal cortical dysplasia type II (13.33% somatic, 6.67% germline). Pathogenic/likely pathogenic positive genes were disorder specific and BRAF V600E the only recurrent pathogenic variant. This study represents a reference for the genetic variant burden across the four most common lesion entities in patients with drug-resistant focal epilepsy. The observed large variability in variant burden by epileptic lesion type calls for whole exome sequencing of histopathologically well-characterized tissue in a diagnostic setting and in research to discover novel disease-associated genes.
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62
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Mao XY, Zhou HH, Jin WL. Ferroptosis Induction in Pentylenetetrazole Kindling and Pilocarpine-Induced Epileptic Seizures in Mice. Front Neurosci 2019; 13:721. [PMID: 31379480 PMCID: PMC6652743 DOI: 10.3389/fnins.2019.00721] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 06/26/2019] [Indexed: 12/21/2022] Open
Abstract
Epilepsy is a serious neurological disorder and is characterized by recurrent and unprovoked seizures. A critical pathological factor in the seizure genesis is neuronal loss. Until now, apart from the known regulatory cell death pathways, ferroptosis is a newly discovered type of cell death with the features of iron accumulation and the excessive production of lipid reactive oxygen species (ROS). In our present work, it was illustrated that ferroptosis occurs in murine models of pentylenetetrazole (PTZ) kindling and pilocarpine (Pilo)-induced seizures. In both of these seizure models, treatment with ferroptosis inhibitor ferrostatin-1 (Fer-1) efficiently alleviates seizures. This was achieved through elevated levels of glutathione peroxidase 4 (GPX4) and glutathione (GSH) as well as inhibitions of lipid degradation products including 4-hydroxynonenal (4-HNE) and malonaldehyde (MDA), iron accumulation, and PTGS2 mRNA in the hippocampus. It was concluded that ferroptosis is involved in seizure genesis in PTZ- and Pilo-treated mice, while the suppression of ferroptosis mitigates PTZ kindling, and Pilo-induced seizures in mice.
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Affiliation(s)
- Xiao-Yuan Mao
- Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha China.,Hunan Key Laboratory of Pharmacogenetics, Institute of Clinical Pharmacology, Central South University, Changsha, China.,Engineering Research Center of Applied Technology of Pharmacogenomics, Ministry of Education, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Changsha, China
| | - Hong-Hao Zhou
- Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha China.,Hunan Key Laboratory of Pharmacogenetics, Institute of Clinical Pharmacology, Central South University, Changsha, China.,Engineering Research Center of Applied Technology of Pharmacogenomics, Ministry of Education, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Changsha, China
| | - Wei-Lin Jin
- Centers for Translational Medicine, Ruikang Hospital, Guangxi University of Chinese Medicine, Nanning, China.,Key Laboratory for Thin Film and Microfabrication Technology of Ministry of Education, Department of Instrument Science and Engineering, School of Electronic Information and Electronic Engineering, Institute of Nano Biomedicine and Engineering, Shanghai Jiao Tong University, Shanghai, China
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63
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Ohgomori T, Jinno S. The expression of keratan sulfate reveals a unique subset of microglia in the mouse hippocampus after pilocarpine-induced status epileptics. J Comp Neurol 2019; 528:14-31. [PMID: 31237692 DOI: 10.1002/cne.24734] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 06/03/2019] [Accepted: 06/18/2019] [Indexed: 12/22/2022]
Abstract
Induction of keratan sulfate in microglia has been found in several animal models of neurological disorders. However, the significance of keratan sulfate-expressing microglia is not fully understood. To address this issue, we analyzed the characteristics of microglia labeled by the 5D4 epitope, a marker of high-sulfated keratan sulfate, in the mouse hippocampus during the latent period after pilocarpine-induced status epilepticus (SE). Only 5D4-negative (5D4- ) microglia were found in the CA1 region of vehicle-treated controls and pilocarpine-treated mice at 1 day after SE onset. A few 5D4+ microglia appeared in the strata oriens and radiatum at 5 days post-SE, and they were distributed into the stratum pyramidale at 14 days post-SE. The expressions of genes related to both anti- and pro-inflammatory cytokines were higher in 5D4+ cells than in 5D4- cells at 5 but not 14 days post-SE. The expressions of genes related to phagocytosis were higher in 5D4+ cells than in 5D4- cells throughout the latent period. The phagocytic activity of microglia, as measured by engulfment of the zymosan bioparticles, was higher in 5D4+ cells than in 5D4- cells. The contact ratios between excitatory synaptic boutons and microglia were also higher in 5D4+ cells than in 5D4- cells at 5 and 14 days post-SE. The excitatory/inhibitory ratios of synaptic boutons within the microglial domain were lower in 5D4+ cells than in 5D4- cells at 14 days post-SE. Our findings indicate that 5D4+ microglia may play some role in epileptogenesis via pruning of excitatory synapses during the latent period after SE.
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Affiliation(s)
- Tomohiro Ohgomori
- Department of Anatomy and Neuroscience, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Shozo Jinno
- Department of Anatomy and Neuroscience, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
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64
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Zhao X, Liao Y, Morgan S, Mathur R, Feustel P, Mazurkiewicz J, Qian J, Chang J, Mathern GW, Adamo MA, Ritaccio AL, Gruenthal M, Zhu X, Huang Y. Noninflammatory Changes of Microglia Are Sufficient to Cause Epilepsy. Cell Rep 2019; 22:2080-2093. [PMID: 29466735 PMCID: PMC5880308 DOI: 10.1016/j.celrep.2018.02.004] [Citation(s) in RCA: 118] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Revised: 12/27/2017] [Accepted: 01/31/2018] [Indexed: 12/25/2022] Open
Abstract
Microglia are well known to play a critical role in maintaining brain homeostasis. However, their role in epileptogenesis has yet to be determined. Here, we demonstrate that elevated mTOR signaling in mouse microglia leads to phenotypic changes, including an amoeboid-like morphology, increased proliferation, and robust phagocytosis activity, but without a significant induction of pro-inflammatory cytokines. We further provide evidence that these noninflammatory changes in microglia disrupt homeostasis of the CNS, leading to reduced synapse density, marked microglial infiltration into hippocampal pyramidal layers, moderate neuronal degeneration, and massive proliferation of astrocytes. Moreover, the mice thus affected develop severe early-onset spontaneous recurrent seizures (SRSs). Therefore, we have revealed an epileptogenic mechanism that is independent of the microglial inflammatory response. Our data suggest that microglia could be an opportune target for epilepsy prevention.
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Affiliation(s)
- Xiaofeng Zhao
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY 12208, USA
| | - Yuan Liao
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, NY 12208, USA
| | - Shannon Morgan
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY 12208, USA
| | - Ramkumar Mathur
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, NY 12208, USA
| | - Paul Feustel
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY 12208, USA
| | - Joseph Mazurkiewicz
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY 12208, USA
| | - Jiang Qian
- Department of Pathology, Albany Medical College, Albany, NY 12208, USA
| | - Julia Chang
- Department of Neurosurgery, Brain Research Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Gary W Mathern
- Department of Neurosurgery, Brain Research Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Matthew A Adamo
- Department of Neurosurgery, Albany Medical College, Albany, NY 12208, USA
| | | | - Michael Gruenthal
- Department of Neurology, Albany Medical College, Albany, NY 12208, USA
| | - Xinjun Zhu
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, NY 12208, USA; Department of Medicine, Albany Medical College, Albany, NY 12208, USA
| | - Yunfei Huang
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY 12208, USA.
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65
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Feng L, Murugan M, Bosco DB, Liu Y, Peng J, Worrell GA, Wang HL, Ta LE, Richardson JR, Shen Y, Wu LJ. Microglial proliferation and monocyte infiltration contribute to microgliosis following status epilepticus. Glia 2019; 67:1434-1448. [PMID: 31179602 DOI: 10.1002/glia.23616] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 03/18/2019] [Accepted: 03/19/2019] [Indexed: 12/15/2022]
Abstract
Microglial activation has been recognized as a major contributor to inflammation of the epileptic brain. Seizures are commonly accompanied by remarkable microgliosis and loss of neurons. In this study, we utilize the CX3CR1GFP/+ CCR2RFP/+ genetic mouse model, in which CX3CR1+ resident microglia and CCR2+ monocytes are labeled with GFP and RFP, respectively. Using a combination of time-lapse two-photon imaging and whole-cell patch clamp recording, we determined the distinct morphological, dynamic, and electrophysiological characteristics of infiltrated monocytes and resident microglia, and the evolution of their behavior at different time points following kainic acid-induced seizures. Seizure activated microglia presented enlarged somas with less ramified processes, whereas, infiltrated monocytes were smaller, highly motile cells that lacked processes. Moreover, resident microglia, but not infiltrated monocytes, proliferate locally in the hippocampus after seizure. Microglial proliferation was dependent on the colony-stimulating factor 1 receptor (CSF-1R) pathway. Pharmacological inhibition of CSF-1R reduced seizure-induced microglial proliferation, which correlated with attenuation of neuronal death without altering acute seizure behaviors. Taken together, we demonstrated that proliferation of activated resident microglia contributes to neuronal death in the hippocampus via CSF-1R after status epilepticus, providing potential therapeutic targets for neuroprotection in epilepsy.
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Affiliation(s)
- Lijie Feng
- School of Basic Medical Sciences, Anhui Medical University, Hefei, Anhui, China.,Department of Cell Biology and Neuroscience, School of Arts and Sciences, Rutgers University, Piscataway, New Jersey
| | - Madhuvika Murugan
- Department of Cell Biology and Neuroscience, School of Arts and Sciences, Rutgers University, Piscataway, New Jersey.,Department of Neurology, Mayo Clinic, Rochester, Minnesota
| | - Dale B Bosco
- Department of Neurology, Mayo Clinic, Rochester, Minnesota
| | - Yong Liu
- Department of Neurology, Mayo Clinic, Rochester, Minnesota
| | - Jiyun Peng
- Department of Cell Biology and Neuroscience, School of Arts and Sciences, Rutgers University, Piscataway, New Jersey.,Department of Neurology, Mayo Clinic, Rochester, Minnesota
| | | | - Hai-Long Wang
- Department of Neurology, Mayo Clinic, Rochester, Minnesota
| | - Lauren E Ta
- Department of Neurology, Mayo Clinic, Rochester, Minnesota
| | - Jason R Richardson
- Department of Environmental Health Sciences, Robert Stempel School of Public Health and Social Work, Florida International University, Miami, Florida
| | - Yuxian Shen
- School of Basic Medical Sciences, Anhui Medical University, Hefei, Anhui, China
| | - Long-Jun Wu
- Department of Cell Biology and Neuroscience, School of Arts and Sciences, Rutgers University, Piscataway, New Jersey.,Department of Neurology, Mayo Clinic, Rochester, Minnesota.,Department of Neuroscience, Mayo Clinic, Jacksonville, Florida.,Department of Immunology, Mayo Clinic, Rochester, Minnesota
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66
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Abstract
BACKGROUND It is well-known that the pharmacokinetics of various drugs are influenced by inflammation. This study evaluated the relationship between C-reactive protein (CRP; an inflammation marker) and the pharmacokinetics of perampanel. METHODS Among 111 patients who underwent measurement of both CRP and perampanel, 23 patients had a serum CRP level exceeding 1.5 mg/dL (CRP-positive). We compared the concentration/dose ratio (CD ratio) of perampanel in these 23 patients between the times when they were CRP-positive and CRP-negative. To evaluate the effect of CRP on the CD ratio, multiple regression analysis was performed with the following covariates: CRP-positive status, body weight, and use of phenytoin, carbamazepine, or phenobarbital, and combinations of these drugs. RESULTS In 10 patients using enzyme-inducing antiepileptic drugs (AEDs), the mean CD ratio increased by 53.5% [from 1389 to 2132 (ng/mL)/(mg/kg)] when they were CRP-positive. In 13 patients without enzyme-inducing AEDs, the mean CD ratio increased by 100.8% [from 3826 ng/mL to 7683 (ng/mL)/(mg/kg)] when they were CRP-positive. By multiple regression analysis, the CRP level was a significant independent determinant of the CD ratio of perampanel. Despite a marked increase of the CD ratio, no adverse events were reported. CONCLUSIONS Irrespective of concomitant administration of enzyme-inducing AEDs, the serum perampanel concentration showed a marked increase in patients with inflammation. However, this increase was not associated with central nervous system toxicity. Although it is unknown whether the concentration of free and/or bound perampanel was increased, it seems likely that dose reduction is unnecessary for elevation of the serum perampanel level in patients with inflammation.
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67
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Benbenishty A, Gadrich M, Cottarelli A, Lubart A, Kain D, Amer M, Shaashua L, Glasner A, Erez N, Agalliu D, Mayo L, Ben-Eliyahu S, Blinder P. Prophylactic TLR9 stimulation reduces brain metastasis through microglia activation. PLoS Biol 2019; 17:e2006859. [PMID: 30921319 PMCID: PMC6469801 DOI: 10.1371/journal.pbio.2006859] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2018] [Revised: 04/17/2019] [Accepted: 02/28/2019] [Indexed: 02/07/2023] Open
Abstract
Brain metastases are prevalent in various types of cancer and are often terminal, given the low efficacy of available therapies. Therefore, preventing them is of utmost clinical relevance, and prophylactic treatments are perhaps the most efficient strategy. Here, we show that systemic prophylactic administration of a toll-like receptor (TLR) 9 agonist, CpG-C, is effective against brain metastases. Acute and chronic systemic administration of CpG-C reduced tumor cell seeding and growth in the brain in three tumor models in mice, including metastasis of human and mouse lung cancer, and spontaneous melanoma-derived brain metastasis. Studying mechanisms underlying the therapeutic effects of CpG-C, we found that in the brain, unlike in the periphery, natural killer (NK) cells and monocytes are not involved in controlling metastasis. Next, we demonstrated that the systemically administered CpG-C is taken up by endothelial cells, astrocytes, and microglia, without affecting blood-brain barrier (BBB) integrity and tumor brain extravasation. In vitro assays pointed to microglia, but not astrocytes, as mediators of CpG- C effects through increased tumor killing and phagocytosis, mediated by direct microglia-tumor contact. In vivo, CpG-C-activated microglia displayed elevated mRNA expression levels of apoptosis-inducing and phagocytosis-related genes. Intravital imaging showed that CpG-C-activated microglia cells contact, kill, and phagocytize tumor cells in the early stages of tumor brain invasion more than nonactivated microglia. Blocking in vivo activation of microglia with minocycline, and depletion of microglia with a colony-stimulating factor 1 inhibitor, indicated that microglia mediate the antitumor effects of CpG-C. Overall, the results suggest prophylactic CpG-C treatment as a new intervention against brain metastasis, through an essential activation of microglia.
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Affiliation(s)
- Amit Benbenishty
- School of Psychological Sciences, Tel Aviv University, Tel Aviv, Israel
- Neurobiology Department, Tel Aviv University, Tel Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Meital Gadrich
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
- School for Molecular Cell Biology & Biotechnology, Tel Aviv University, Tel Aviv, Israel
| | - Azzurra Cottarelli
- Department of Neurology, Columbia University Medical Center, New York, New York, United States of America
| | - Alisa Lubart
- Neurobiology Department, Tel Aviv University, Tel Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - David Kain
- Neurobiology Department, Tel Aviv University, Tel Aviv, Israel
| | - Malak Amer
- Department of Pathology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Lee Shaashua
- School of Psychological Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Ariella Glasner
- The Lautenberg Centre for General and Tumor Immunology, The Hebrew University Hadassah Medical School, Jerusalem, Israel
| | - Neta Erez
- Department of Pathology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Dritan Agalliu
- Department of Neurology, Columbia University Medical Center, New York, New York, United States of America
| | - Lior Mayo
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
- School for Molecular Cell Biology & Biotechnology, Tel Aviv University, Tel Aviv, Israel
| | - Shamgar Ben-Eliyahu
- School of Psychological Sciences, Tel Aviv University, Tel Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Pablo Blinder
- Neurobiology Department, Tel Aviv University, Tel Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
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68
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Matsuda T, Irie T, Katsurabayashi S, Hayashi Y, Nagai T, Hamazaki N, Adefuin AMD, Miura F, Ito T, Kimura H, Shirahige K, Takeda T, Iwasaki K, Imamura T, Nakashima K. Pioneer Factor NeuroD1 Rearranges Transcriptional and Epigenetic Profiles to Execute Microglia-Neuron Conversion. Neuron 2019; 101:472-485.e7. [PMID: 30638745 DOI: 10.1016/j.neuron.2018.12.010] [Citation(s) in RCA: 142] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 10/23/2018] [Accepted: 12/05/2018] [Indexed: 02/07/2023]
Abstract
Minimal sets of transcription factors can directly reprogram somatic cells into neurons. However, epigenetic remodeling during neuronal reprogramming has not been well reconciled with transcriptional regulation. Here we show that NeuroD1 achieves direct neuronal conversion from mouse microglia both in vitro and in vivo. Exogenous NeuroD1 initially occupies closed chromatin regions associated with bivalent trimethylation of histone H3 at lysine 4 (H3K4me3) and H3K27me3 marks in microglia to induce neuronal gene expression. These regions are resolved to a monovalent H3K4me3 mark at later stages of reprogramming to establish the neuronal identity. Furthermore, the transcriptional repressors Scrt1 and Meis2 are induced as NeuroD1 target genes, resulting in a decrease in the expression of microglial genes. In parallel, the microglial epigenetic signature in promoter and enhancer regions is erased. These findings reveal NeuroD1 pioneering activity accompanied by global epigenetic remodeling for two sequential events: onset of neuronal property acquisition and loss of the microglial identity during reprogramming.
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Affiliation(s)
- Taito Matsuda
- Department of Stem Cell Biology and Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
| | - Takashi Irie
- Department of Stem Cell Biology and Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Shutaro Katsurabayashi
- Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan
| | - Yoshinori Hayashi
- Department of Aging Science and Pharmacology, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Tatsuya Nagai
- Department of Stem Cell Biology and Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Nobuhiko Hamazaki
- Department of Stem Cell Biology and Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Aliya Mari D Adefuin
- Department of Stem Cell Biology and Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Fumihito Miura
- Department of Biochemistry, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Takashi Ito
- Department of Biochemistry, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Hiroshi Kimura
- Cell Biology Unit, Institute of Innovative Research, Tokyo Institute of Technology, Tokyo, Japan
| | - Katsuhiko Shirahige
- Laboratory of Genome Structure and Function, Research Center for Epigenetic Disease, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo, Japan
| | - Tadayuki Takeda
- Genome Network Analysis Support Facility (GeNAS), RIKEN Center for Life Science Technologies, Kanagawa, Japan
| | - Katsunori Iwasaki
- Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan
| | - Takuya Imamura
- Department of Stem Cell Biology and Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Kinichi Nakashima
- Department of Stem Cell Biology and Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
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Embryonic Neocortical Microglia Express Toll-Like Receptor 9 and Respond to Plasmid DNA Injected into the Ventricle: Technical Considerations Regarding Microglial Distribution in Electroporated Brain Walls. eNeuro 2018; 5:eN-MNT-0312-18. [PMID: 30627652 PMCID: PMC6325556 DOI: 10.1523/eneuro.0312-18.2018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 10/19/2018] [Accepted: 10/27/2018] [Indexed: 12/25/2022] Open
Abstract
Microglia, the resident immune cells in the CNS, play multiple roles during development. In the embryonic cerebral wall, microglia modulate the functions of neural stem/progenitor cells through their distribution in regions undergoing cell proliferation and/or differentiation. Previous studies using CX3CR1-GFP transgenic mice demonstrated that microglia extensively survey these regions. To simultaneously visualize microglia and neural-lineage cells that interact with each other, we applied the in utero electroporation (IUE) technique, which has been widely used for gene-transfer in neurodevelopmental studies, to CX3CR1-GFP mice (males and females). However, we unexpectedly faced a technical problem: although microglia are normally distributed homogeneously throughout the mid-embryonic cortical wall with only limited luminal entry, the intraventricular presence of exogenously derived plasmid DNAs induced microglia to accumulate along the apical surface of the cortex and aggregate in the choroid plexus. This effect was independent of capillary needle puncture of the brain wall or application of electrical pulses. The microglial response occurred at plasmid DNA concentrations lower than those routinely used for IUE, and was mediated by activation of Toll-like receptor 9 (TLR9), an innate immune sensor that recognizes unmethylated cytosine-phosphate guanosine motifs abundant in microbial DNA. Administration of plasmid DNA together with oligonucleotide 2088, the antagonist of TLR9, partially restored the dispersed intramural localization of microglia and significantly decreased luminal accumulation of these cells. Thus, via TLR9, intraventricular plasmid DNA administration causes aberrant distribution of embryonic microglia, suggesting that the behavior of microglia in brain primordia subjected to IUE should be carefully interpreted.
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70
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Fiebich BL, Batista CRA, Saliba SW, Yousif NM, de Oliveira ACP. Role of Microglia TLRs in Neurodegeneration. Front Cell Neurosci 2018; 12:329. [PMID: 30333729 PMCID: PMC6176466 DOI: 10.3389/fncel.2018.00329] [Citation(s) in RCA: 187] [Impact Index Per Article: 31.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 09/10/2018] [Indexed: 12/13/2022] Open
Abstract
Toll-like receptors (TLRs) are a group of receptors widely distributed in the organism. In the central nervous system, they are expressed in neurons, astrocytes and microglia. Although their involvement in immunity is notorious, different articles have demonstrated their roles in physiological and pathological conditions, including neurodegeneration. There is increasing evidence of an involvement of TLRs, especially TLR2, 4 and 9 in neurodegenerative diseases such as Alzheimer’s disease (AD), Parkinson’s disease (PD), and amyotrophic lateral sclerosis (ALS). In this sense, their expression in microglia might modulate the activity of these cells, which in turn, lead to protective or deleterious effects over neurons and other cells. Therefore, TLRs might mediate the link between inflammation and neurodegenerative diseases. However, further studies have to be performed to elucidate the role of the other TLRs in these diseases and to further prove and confirm the pathophysiological role of all TLRs in neurodegeneration. In this article, we revise and summarize the current knowledge regarding the role of TLRs in neurodegeneration with the focus on the possible functions of these receptors in microglia.
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Affiliation(s)
- Bernd L Fiebich
- Neuroimmunology and Neurochemistry Research Group, Department of Psychiatry and Psychotherapy, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | | | - Soraya Wilke Saliba
- Neuroimmunology and Neurochemistry Research Group, Department of Psychiatry and Psychotherapy, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Nizar M Yousif
- Neuroimmunology and Neurochemistry Research Group, Department of Psychiatry and Psychotherapy, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany
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71
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Chen SD, Yang JL, Hwang WC, Yang DI. Emerging Roles of Sonic Hedgehog in Adult Neurological Diseases: Neurogenesis and Beyond. Int J Mol Sci 2018; 19:ijms19082423. [PMID: 30115884 PMCID: PMC6121355 DOI: 10.3390/ijms19082423] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2018] [Revised: 08/10/2018] [Accepted: 08/13/2018] [Indexed: 12/14/2022] Open
Abstract
Sonic hedgehog (Shh), a member of the hedgehog (Hh) family, was originally recognized as a morphogen possessing critical characters for neural development during embryogenesis. Recently, however, Shh has emerged as an important modulator in adult neural tissues through different mechanisms such as neurogenesis, anti-oxidation, anti-inflammation, and autophagy. Therefore, Shh may potentially have clinical application in neurodegenerative diseases and brain injuries. In this article, we present some examples, including ours, to show different aspects of Shh signaling and how Shh agonists or mimetics are used to alter the neuronal fates in various disease models, both in vitro and in vivo. Other potential mechanisms that are discussed include alteration of mitochondrial function and anti-aging effect; both are critical for age-related neurodegenerative diseases. A thorough understanding of the protective mechanisms elicited by Shh may provide a rationale to design innovative therapeutic regimens for various neurodegenerative diseases.
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Affiliation(s)
- Shang-Der Chen
- Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung City 83301, Taiwan.
- Institute for Translational Research in Biomedicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung City 83301, Taiwan.
- College of Medicine, Chang Gung University, Taoyuan City 33302, Taiwan.
| | - Jenq-Lin Yang
- Institute for Translational Research in Biomedicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung City 83301, Taiwan.
| | - Wei-Chao Hwang
- Department of Neurology, Taipei City Hospital, Taipei 11556, Taiwan.
| | - Ding-I Yang
- Institute of Brain Science, National Yang-Ming University, Taipei 11221, Taiwan.
- Brain Research Center, National Yang-Ming University, Taipei 11221, Taiwan.
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72
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Schindler SM, Frank MG, Annis JL, Maier SF, Klegeris A. Pattern recognition receptors mediate pro-inflammatory effects of extracellular mitochondrial transcription factor A (TFAM). Mol Cell Neurosci 2018; 89:71-79. [DOI: 10.1016/j.mcn.2018.04.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 04/09/2018] [Accepted: 04/13/2018] [Indexed: 12/11/2022] Open
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Ectopic neurogenesis induced by prenatal antiepileptic drug exposure augments seizure susceptibility in adult mice. Proc Natl Acad Sci U S A 2018; 115:4270-4275. [PMID: 29610328 PMCID: PMC5910824 DOI: 10.1073/pnas.1716479115] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Recent clinical studies suggest that environmental insults, such as valproic acid (VPA) exposure, in utero can have adverse effects on brain function of the offspring in later life, although the underlying mechanisms of these impairments remain poorly understood. By focusing on the property of neural stem/progenitor cells (NS/PCs) residing in the adult hippocampus, we identified the mechanism of increased seizure sensitivity in prenatally VPA-exposed adult mice. Furthermore, we found that voluntary exercise can overcome the adverse effects through normalizing VPA-induced transcriptome alterations in NS/PCs. We believe that our study provides insights for further understanding and developing treatment strategies for neurological disorders induced by prenatal environmental insults. Epilepsy is a neurological disorder often associated with seizure that affects ∼0.7% of pregnant women. During pregnancy, most epileptic patients are prescribed antiepileptic drugs (AEDs) such as valproic acid (VPA) to control seizure activity. Here, we show that prenatal exposure to VPA in mice increases seizure susceptibility in adult offspring through mislocalization of newborn neurons in the hippocampus. We confirmed that neurons newly generated from neural stem/progenitor cells (NS/PCs) are integrated into the granular cell layer in the adult hippocampus; however, prenatal VPA treatment altered the expression in NS/PCs of genes associated with cell migration, including CXC motif chemokine receptor 4 (Cxcr4), consequently increasing the ectopic localization of newborn neurons in the hilus. We also found that voluntary exercise in a running wheel suppressed this ectopic neurogenesis and countered the enhanced seizure susceptibility caused by prenatal VPA exposure, probably by normalizing the VPA-disrupted expression of multiple genes including Cxcr4 in adult NS/PCs. Replenishing Cxcr4 expression alone in NS/PCs was sufficient to overcome the aberrant migration of newborn neurons and increased seizure susceptibility in VPA-exposed mice. Thus, prenatal exposure to an AED, VPA, has a long-term effect on the behavior of NS/PCs in offspring, but this effect can be counteracted by a simple physical activity. Our findings offer a step to developing strategies for managing detrimental effects in offspring exposed to VPA in utero.
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74
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Hiragi T, Ikegaya Y, Koyama R. Microglia after Seizures and in Epilepsy. Cells 2018; 7:cells7040026. [PMID: 29597334 PMCID: PMC5946103 DOI: 10.3390/cells7040026] [Citation(s) in RCA: 100] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 03/24/2018] [Accepted: 03/26/2018] [Indexed: 01/23/2023] Open
Abstract
Microglia are the resident immune cells in the brain that constitute the brain’s innate immune system. Recent studies have revealed various functions of microglia in the development and maintenance of the central nervous system (CNS) in both health and disease. However, the role of microglia in epilepsy remains largely undiscovered, partly because of the complex phenotypes of activated microglia. Activated microglia likely exert different effects on brain function depending on the phase of epileptogenesis. In this review, we mainly focus on the animal models of temporal lobe epilepsy (TLE) and discuss the proepileptic and antiepileptic roles of activated microglia in the epileptic brain. Specifically, we focus on the roles of microglia in the production of inflammatory cytokines, regulation of neurogenesis, and surveillance of the surrounding environment in epilepsy.
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Affiliation(s)
- Toshimitsu Hiragi
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8654, Japan.
| | - Yuji Ikegaya
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8654, Japan.
| | - Ryuta Koyama
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8654, Japan.
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75
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Seong KJ, Kim HJ, Cai B, Kook MS, Jung JY, Kim WJ. Toll-like receptor 2 promotes neurogenesis from the dentate gyrus after photothrombotic cerebral ischemia in mice. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2018; 22:145-153. [PMID: 29520167 PMCID: PMC5840073 DOI: 10.4196/kjpp.2018.22.2.145] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 11/03/2017] [Accepted: 12/07/2017] [Indexed: 01/27/2023]
Abstract
The subgranular zone (SGZ) of hippocampal dentate gyrus (HDG) is a primary site of adult neurogenesis. Toll-like receptors (TLRs), are involved in neural system development of Drosophila and innate immune response of mammals. TLR2 is expressed abundantly in neurogenic niches such as adult mammalian hippocampus. It regulates adult hippocampal neurogenesis. However, the role of TLR2 in adult neurogenesis is not well studied in global or focal cerebral ischemia. Therefore, this study aimed to investigate the role of TLR2 in adult neurogenesis after photochemically induced cerebral ischemia. At 7 days after photothrombotic ischemic injury, the number of bromodeoxyuridine (BrdU)-positive cells was increased in both TLR2 knock-out (KO) mice and wild-type (WT) mice. However, the increment rate of BrdU-positive cells was lower in TLR2 KO mice compared to that in WT mice. The number of doublecortin (DCX) and neuronal nuclei (NeuN)-positive cells in HDG was decreased after photothrombotic ischemia in TLR2 KO mice compared to that in WT mice. The survival rate of cells in HDG was decreased in TLR2 KO mice compared to that in WT mice. In contrast, the number of cleaved-caspase 3 (apoptotic marker) and the number of GFAP (glia marker)/BrdU double-positive cells in TLR2 KO mice were higher than that in WT mice. These results suggest that TLR2 can promote adult neurogenesis from neural stem cell of hippocampal dentate gyrus through increasing proliferation, differentiation, and survival from neural stem cells after ischemic injury of the brain.
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Affiliation(s)
- Kyung-Joo Seong
- Dental Science Research Institute, Department of Oral Physiology, School of Dentistry, Chonnam National University, Gwangju 61186, Korea
| | - Hyeong-Jun Kim
- Dental Science Research Institute, Department of Oral Physiology, School of Dentistry, Chonnam National University, Gwangju 61186, Korea
| | - Bangrong Cai
- Dental Science Research Institute, Department of Oral Physiology, School of Dentistry, Chonnam National University, Gwangju 61186, Korea
| | - Min-Suk Kook
- Department of Oral and Maxillofacial Surgery, School of Dentistry, Chonnam National University, Gwangju 61186, Korea
| | - Ji-Yeon Jung
- Dental Science Research Institute, Department of Oral Physiology, School of Dentistry, Chonnam National University, Gwangju 61186, Korea
| | - Won-Jae Kim
- Dental Science Research Institute, Department of Oral Physiology, School of Dentistry, Chonnam National University, Gwangju 61186, Korea
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76
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Neuroinflammation and physical exercise as modulators of adult hippocampal neural precursor cell behavior. Rev Neurosci 2017; 29:1-20. [DOI: 10.1515/revneuro-2017-0024] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 06/29/2017] [Indexed: 12/15/2022]
Abstract
Abstract
The dentate gyrus of the hippocampus is a plastic structure where adult neurogenesis constitutively occurs. Cell components of the neurogenic niche are source of paracrine as well as membrane-bound factors such as Notch, Bone Morphogenetic Proteins, Wnts, Sonic Hedgehog, cytokines, and growth factors that regulate adult hippocampal neurogenesis and cell fate decision. The integration and coordinated action of multiple extrinsic and intrinsic cues drive a continuous decision process: if adult neural stem cells remain quiescent or proliferate, if they take a neuronal or a glial lineage, and if new cells proliferate, undergo apoptotic death, or survive. The proper balance in the molecular milieu of this neurogenic niche leads to the production of neurons in a higher rate as that of astrocytes. But this rate changes in face of microenvironment modifications as those driven by physical exercise or with neuroinflammation. In this work, we first review the cellular and molecular components of the subgranular zone, focusing on the molecules, active signaling pathways and genetic programs that maintain quiescence, induce proliferation, or promote differentiation. We then summarize the evidence regarding the role of neuroinflammation and physical exercise in the modulation of adult hippocampal neurogenesis with emphasis on the activation of progression from adult neural stem cells to lineage-committed progenitors to their progeny mainly in murine models.
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77
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Lannes N, Eppler E, Etemad S, Yotovski P, Filgueira L. Microglia at center stage: a comprehensive review about the versatile and unique residential macrophages of the central nervous system. Oncotarget 2017; 8:114393-114413. [PMID: 29371994 PMCID: PMC5768411 DOI: 10.18632/oncotarget.23106] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 11/15/2017] [Indexed: 02/07/2023] Open
Abstract
Microglia cells are the unique residential macrophages of the central nervous system (CNS). They have a special origin, as they derive from the embryonic yolk sac and enter the developing CNS at a very early stage. They play an important role during CNS development and adult homeostasis. They have a major contribution to adult neurogenesis and neuroinflammation. Thus, they participate in the pathogenesis of neurodegenerative diseases and contribute to aging. They play an important role in sustaining and breaking the blood-brain barrier. As innate immune cells, they contribute substantially to the immune response against infectious agents affecting the CNS. They play also a major role in the growth of tumours of the CNS. Microglia are consequently the key cell population linking the nervous and the immune system. This review covers all different aspects of microglia biology and pathology in a comprehensive way.
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Affiliation(s)
- Nils Lannes
- Albert Gockel, Anatomy, Department of Medicine, University of Fribourg, CH-1700 Fribourg, Switzerland
| | - Elisabeth Eppler
- Pestalozzistrasse Zo, Department of BioMedicine, University of Basel, CH-4056 Basel, Switzerland
| | - Samar Etemad
- Building 71/218 RBWH Herston, Centre for Clinical Research, The University of Queensland, QLD 4029 Brisbane, Australia
| | - Peter Yotovski
- Albert Gockel, Anatomy, Department of Medicine, University of Fribourg, CH-1700 Fribourg, Switzerland
| | - Luis Filgueira
- Albert Gockel, Anatomy, Department of Medicine, University of Fribourg, CH-1700 Fribourg, Switzerland
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78
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Hsieh J, Zhang CL. Neurogenesis in Cancun: where science meets the sea. Development 2017; 143:1649-54. [PMID: 27190035 DOI: 10.1242/dev.138412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 04/11/2016] [Indexed: 11/20/2022]
Abstract
In March 2016, meeting organizers Sebastian Jessberger and Hongjun Song brought together over 100 scientists from around the world to Cancun, Mexico to present the latest research on neurogenesis. The meeting covered diverse aspects of embryonic and adult neurogenesis with a focus on novel technologies, including chemogenetics and optogenetics, live cell two-photon imaging, cell fate reprogramming and human pluripotent stem cell models. This Meeting Review describes the exciting work that was presented and some of the emerging themes from the meeting.
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Affiliation(s)
- Jenny Hsieh
- Department of Molecular Biology, Hamon Center for Regenerative Science and Medicine, UT Southwestern Medical Center, Dallas, TX 75390-9148, USA
| | - Chun-Li Zhang
- Department of Molecular Biology, Hamon Center for Regenerative Science and Medicine, UT Southwestern Medical Center, Dallas, TX 75390-9148, USA
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79
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High-glucose induces tau hyperphosphorylation through activation of TLR9-P38MAPK pathway. Exp Cell Res 2017; 359:312-318. [PMID: 28803064 DOI: 10.1016/j.yexcr.2017.07.032] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 07/24/2017] [Accepted: 07/26/2017] [Indexed: 12/22/2022]
Abstract
Diabetic encephalopathy (DE) is one of the most common complications of diabetes. The major pathological variations include neurofibrillary tangles (NFTs), which are caused by tau hyperphosphorylation, and senile plaques (SPs) consisting of amyloid β- protein(Aβ) deposits. In recent years, DE research studies have focused on exploring the activation of the inflammatory signaling pathway in immune cells. Toll-like receptor 9 (TLR9) is well known to regulate the inflammatory reactions in immune processes. During the tau hyperphosphorylation process, TLR9 in microglia plays bidirectional roles. However, no studies have clearly demonstrated the relationship between TLR9 and tau hyperphosphorylation in neurons. Based on our experiments, we found significant increase in TLR9 expression in neurons and an increase in tau hyperphosphorylation in high-glucose media. However, these alterations can be reversed by TLR9 inhibitor. Furthermore, we specifically inhibited the activation of P38mitogenactivated protein kinase(P38MAPK) and found an effective decrease in tau hyperphosphorylation. This effect is likely related to Unc93b1. Meanwhile, High glucose levels can induce neuronal apoptosis via the TLR9 signaling pathway. Our studies are the first to reveal that high glucose can regulate tau hyperphosphorylation and neuronal apoptosis via TLR9-P38MAPK signaling pathway. These findings provide a new method for studying the mechanism underlying DE.
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80
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Chemokine CCL2-CCR2 Signaling Induces Neuronal Cell Death via STAT3 Activation and IL-1β Production after Status Epilepticus. J Neurosci 2017; 37:7878-7892. [PMID: 28716963 DOI: 10.1523/jneurosci.0315-17.2017] [Citation(s) in RCA: 124] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Revised: 06/20/2017] [Accepted: 07/12/2017] [Indexed: 12/17/2022] Open
Abstract
Elevated levels of chemokine C-C motif ligand 2 (CCL2) and its receptor CCR2 have been reported in patients with temporal lobe epilepsy and in experimental seizures. However, the functional significance and molecular mechanism underlying CCL2-CCR2 signaling in epileptic brain remains largely unknown. In this study, we found that the upregulated CCL2 was mainly expressed in hippocampal neurons and activated microglia from mice 1 d after kainic acid (KA)-induced seizures. Taking advantage of CX3CR1GFP/+:CCR2RFP/+ double-transgenic mice, we demonstrated that CCL2-CCR2 signaling has a role in resident microglial activation and blood-derived monocyte infiltration. Moreover, seizure-induced degeneration of neurons in the hippocampal CA3 region was attenuated in mice lacking CCL2 or CCR2. We further showed that CCR2 activation induced STAT3 (signal transducer and activator of transcription 3) phosphorylation and IL-1β production, which are critical for promoting neuronal cell death after status epilepticus. Consistently, pharmacological inhibition of STAT3 by WP1066 reduced seizure-induced IL-1β production and subsequent neuronal death. Two weeks after KA-induced seizures, CCR2 deficiency not only reduced neuronal loss, but also attenuated seizure-induced behavioral impairments, including anxiety, memory decline, and recurrent seizure severity. Together, we demonstrated that CCL2-CCR2 signaling contributes to neurodegeneration via STAT3 activation and IL-1β production after status epilepticus, providing potential therapeutic targets for the treatment of epilepsy.SIGNIFICANCE STATEMENT Epilepsy is a global concern and epileptic seizures occur in many neurological conditions. Neuroinflammation associated with microglial activation and monocyte infiltration are characteristic of epileptic brains. However, molecular mechanisms underlying neuroinflammation in neuronal death following epilepsy remain to be elucidated. Here we demonstrate that CCL2-CCR2 signaling is required for monocyte infiltration, which in turn contributes to kainic acid (KA)-induced neuronal cell death. The downstream of CCR2 activation involves STAT3 (signal transducer and activator of transcription 3) phosphorylation and IL-1β production. Two weeks after KA-induced seizures, CCR2 deficiency not only reduced neuronal loss, but also attenuated seizure-induced behavioral impairments, including anxiety, memory decline, and recurrent seizure severity. The current study provides a novel insight on the function and mechanisms of CCL2-CCR2 signaling in KA-induced neurodegeneration and behavioral deficits.
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81
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Klein RS, Hunter CA. Protective and Pathological Immunity during Central Nervous System Infections. Immunity 2017; 46:891-909. [PMID: 28636958 PMCID: PMC5662000 DOI: 10.1016/j.immuni.2017.06.012] [Citation(s) in RCA: 99] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Revised: 06/05/2017] [Accepted: 06/05/2017] [Indexed: 02/08/2023]
Abstract
The concept of immune privilege of the central nervous system (CNS) has dominated the study of inflammatory processes in the brain. However, clinically relevant models have highlighted that innate pathways limit pathogen invasion of the CNS and adaptive immunity mediates control of many neural infections. As protective responses can result in bystander damage, there are regulatory mechanisms that balance protective and pathological inflammation, but these mechanisms might also allow microbial persistence. The focus of this review is to consider the host-pathogen interactions that influence neurotropic infections and to highlight advances in our understanding of innate and adaptive mechanisms of resistance as key determinants of the outcome of CNS infection. Advances in these areas have broadened our comprehension of how the immune system functions in the brain and can readily overcome immune privilege.
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Affiliation(s)
- Robyn S Klein
- Departments of Medicine, Pathology and Immunology, Neuroscience, Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - Christopher A Hunter
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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82
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Sadangi C, Rosenow F, Norwood BA. Validation of reference genes for quantitative gene expression analysis in experimental epilepsy. J Neurosci Res 2017; 95:2357-2366. [PMID: 28573671 DOI: 10.1002/jnr.24089] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 04/27/2017] [Accepted: 05/04/2017] [Indexed: 02/06/2023]
Abstract
To grasp the molecular mechanisms and pathophysiology underlying epilepsy development (epileptogenesis) and epilepsy itself, it is important to understand the gene expression changes that occur during these phases. Quantitative real-time polymerase chain reaction (qPCR) is a technique that rapidly and accurately determines gene expression changes. It is crucial, however, that stable reference genes are selected for each experimental condition to ensure that accurate values are obtained for genes of interest. If reference genes are unstably expressed, this can lead to inaccurate data and erroneous conclusions. To date, epilepsy studies have used mostly single, nonvalidated reference genes. This is the first study to systematically evaluate reference genes in male Sprague-Dawley rat models of epilepsy. We assessed 15 potential reference genes in hippocampal tissue obtained from 2 different models during epileptogenesis, 1 model during chronic epilepsy, and a model of noninjurious seizures. Reference gene ranking varied between models and also differed between epileptogenesis and chronic epilepsy time points. There was also some variance between the four mathematical models used to rank reference genes. Notably, we found novel reference genes to be more stably expressed than those most often used in experimental epilepsy studies. The consequence of these findings is that reference genes suitable for one epilepsy model may not be appropriate for others and that reference genes can change over time. It is, therefore, critically important to validate potential reference genes before using them as normalizing factors in expression analysis in order to ensure accurate, valid results.
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Affiliation(s)
| | - Felix Rosenow
- Department of Neurology, Philipps University, Marburg, Germany.,Epilepsy Center Frankfurt Rhine-Main, Department of Neurology, Goethe University, Frankfurt am Main, Germany
| | - Braxton A Norwood
- Department of Neurology, Philipps University, Marburg, Germany.,Epilepsy Center Frankfurt Rhine-Main, Department of Neurology, Goethe University, Frankfurt am Main, Germany.,Expesicor LLC, Neuroscience Division, Kalispell, Montana
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83
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Zhang P, Zhang N, Liu L, Zheng K, Zhu L, Zhu J, Cao L, Jiang Y, Liu G, He Q. Polymorphisms of toll-like receptors 2 and 9 and severity and prognosis of bacterial meningitis in Chinese children. Sci Rep 2017; 7:42796. [PMID: 28202935 PMCID: PMC5311876 DOI: 10.1038/srep42796] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 01/13/2017] [Indexed: 02/07/2023] Open
Abstract
Toll-like receptors (TLRs) play a crucial role in innate immunity, protecting the host from bacterial pathogens. We investigated whether bacterial meningitis (BM) in children was associated with gene polymorphisms in TLR2 (rs3804099), TLR3 (rs3775291 and rs3775290) and TLR9 (rs352139 and rs352140). Blood samples were taken from 218 child patients with confirmed BM and 330 healthy adult controls (HC) and polymorphisms of these genes were analyzed by PCR-based sequencing. For TLR2 rs3804099, frequencies of the minor allele C were markedly higher in patients with severe BM (defined as CSF glucose concentration ≤ 1.5 mmol/L and seizures) than those without (43.5% and 40.1% vs. 30.1% and 29.1%, p = 0.008 and p = 0.016, respectively). For TLR9 rs352139, patients who carried genotype AA and minor allele A developed seizures less often than those without (OR = 0.289, p = 0.003 and OR = 0.568, p = 0.004, respectively). However, for TLR9 rs352140, patients who carried genotype TT and minor allele T developed seizures more often than those without (OR = 3.385, p = 0.004 and OR = 1.767, p = 0.004, respectively). Our finding suggested that genetic variations in TLR2 and TLR9 are associated with severity and prognosis of bacterial meningitis in Chinese children. However, the results should be interpreted with caution since the number of subjects included was limited.
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Affiliation(s)
- Pingping Zhang
- Department of Infectious Diseases, Beijing Children's Hospital, Capital Medical University, Beijing 100045, China
| | - Nan Zhang
- Department of Medical Microbiology and Research Centre of Microbiome, Capital Medical University, Beijing 100069, China
| | - Linlin Liu
- Department of Infectious Diseases, Beijing Children's Hospital, Capital Medical University, Beijing 100045, China
| | - Kai Zheng
- Department of Medical Microbiology and Research Centre of Microbiome, Capital Medical University, Beijing 100069, China
| | - Liang Zhu
- Department of Infectious Diseases, Beijing Children's Hospital, Capital Medical University, Beijing 100045, China
| | - Junping Zhu
- Department of Medical Microbiology and Research Centre of Microbiome, Capital Medical University, Beijing 100069, China
| | - Lina Cao
- Department of Medical Microbiology and Research Centre of Microbiome, Capital Medical University, Beijing 100069, China
| | - Yiyuan Jiang
- Department of Medical Microbiology and Research Centre of Microbiome, Capital Medical University, Beijing 100069, China
| | - Gang Liu
- Department of Infectious Diseases, Beijing Children's Hospital, Capital Medical University, Beijing 100045, China
| | - Qiushui He
- Department of Medical Microbiology and Research Centre of Microbiome, Capital Medical University, Beijing 100069, China.,Department of Medical Microbiology and Immunology, University of Turku, Turku 20520, Finland
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84
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Sawano T, Tsuchihashi R, Morii E, Watanabe F, Nakane K, Inagaki S. Homology analysis detects topological changes of Iba1 localization accompanied by microglial activation. Neuroscience 2017; 346:43-51. [PMID: 28077279 DOI: 10.1016/j.neuroscience.2016.12.052] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2016] [Revised: 12/21/2016] [Accepted: 12/29/2016] [Indexed: 01/01/2023]
Abstract
The state of microglial activation provides important information about the central nervous system. However, a reliable index of microglial activation in histological samples has yet to be established. Here, we show that microglial activation induces topological changes of Iba1 localization that can be detected by analysis based on homology theory. Analysis of homology was applied to images of Iba1-stained tissue sections, and the 0-dimentional Betti number (b0: the number of solid components) and the 1-dimentional Betti number (b1: the number of windows surrounded by solid components) were obtained. We defined b1/b0 as the Homology Value (HV), and investigated its validity as an index of microglial activation using cerebral ischemia model mice. Microglial activation was accompanied by changes to Iba1 localization and morphology of microglial processes. In single microglial cells, the change of Iba1 localization increased b1. Conversely, thickening or retraction of microglial processes decreased b0. Consequently, microglial activation increased the HV. The HV of a tissue area increased with proximity to the ischemic core and showed a high degree of concordance with the number of microglia expressing activation makers. Furthermore, the HV of human metastatic brain tumor tissue also increased with proximity to the tumor. These results suggest that our index, based on homology theory, can be used to correctly evaluate microglial activation in various tissue images.
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Affiliation(s)
- Toshinori Sawano
- Group of Neurobiology, Division of Health Sciences, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Ryo Tsuchihashi
- Group of Neurobiology, Division of Health Sciences, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Eiichi Morii
- Department of Pathology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Fumiya Watanabe
- Group of Neurobiology, Division of Health Sciences, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Kazuaki Nakane
- Division of Health Sciences, Graduate School of Medicine, Osaka University, Osaka, Japan.
| | - Shinobu Inagaki
- Group of Neurobiology, Division of Health Sciences, Graduate School of Medicine, Osaka University, Osaka, Japan.
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85
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Cai Q, Li Y, Mao J, Pei G. Neurogenesis-Promoting Natural Product α-Asarone Modulates Morphological Dynamics of Activated Microglia. Front Cell Neurosci 2016; 10:280. [PMID: 28018174 PMCID: PMC5145874 DOI: 10.3389/fncel.2016.00280] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 11/21/2016] [Indexed: 11/13/2022] Open
Abstract
α-Asarone is an active constituent of Acori Tatarinowii, one of the widely used traditional Chinese Medicine to treat cognitive defect, and recently is shown to promote neurogenesis. Here, we demonstrated that low level (3 μM) of α-asarone attenuated LPS-induced BV2 cell bipolar elongated morphological change, with no significant effect on the LPS-induced pro-inflammatory cytokine expressions. In addition, time-lapse analysis also revealed that α-asarone modulated LPS-induced BV2 morphological dynamics. Consistently a significant reduction in the LPS-induced Monocyte Chemoattractant Protein (MCP-1) mRNA and protein levels was also detected along with the morphological change. Mechanistic study showed that the attenuation effect to the LPS-resulted morphological modulation was also detected in the presence of MCP-1 antibodies or a CCR2 antagonist. This result has also been confirmed in primary cultured microglia. The in vivo investigation provided further evidence that α-asarone reduced the proportion of activated microglia, and reduced microglial tip number and maintained the velocity. Our study thus reveals α-asarone effectively modulates microglial morphological dynamics, and implies this effect of α-asarone may functionally relate to its influence on neurogenesis.
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Affiliation(s)
- Qing Cai
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of SciencesShanghai, China; Graduate School, University of Chinese Academy of Sciences, Chinese Academy of SciencesShanghai, China
| | - Yuanyuan Li
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of SciencesShanghai, China; Graduate School, University of Chinese Academy of Sciences, Chinese Academy of SciencesShanghai, China
| | - Jianxin Mao
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of SciencesShanghai, China; Graduate School, University of Chinese Academy of Sciences, Chinese Academy of SciencesShanghai, China
| | - Gang Pei
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of SciencesShanghai, China; School of Life Science and Technology, and the Collaborative Innovation Center for Brain Science, Tongji UniversityShanghai, China
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86
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Luo C, Ikegaya Y, Koyama R. Microglia and neurogenesis in the epileptic dentate gyrus. NEUROGENESIS 2016; 3:e1235525. [PMID: 27928548 DOI: 10.1080/23262133.2016.1235525] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 09/05/2016] [Accepted: 09/07/2016] [Indexed: 01/22/2023]
Abstract
Microglia are recognized as major immune cells in the brain. They have been traditionally studied in various contexts of disease, where their activation has been assumed to induce mostly detrimental effects. Recent studies, however, have challenged the current view of microglia, clarifying their essential contribution to the development of neural circuits and brain function. In this review, we particularly discuss the role of microglia as the major orchestrators that regulate adult neurogenesis in the hippocampus. We also review the roles of microglia in seizure-induced adult neurogenesis in the epileptic dentate gyrus. Specifically, we introduce our recent study, in which we identified a novel mechanism by which viable newborn cells in the adult dentate gyrus are phagocytosed and eliminated by microglia after status epilepticus, maintaining homeostasis of the dentate circuitry. This review aims to reconsider the microglial function in adult neurogenesis, especially when they are activated during epileptogenesis, challenging the dogma that microglia are harmful neurotoxic cells.
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Affiliation(s)
- Cong Luo
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo , Tokyo, Japan
| | - Yuji Ikegaya
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo , Tokyo, Japan
| | - Ryuta Koyama
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo , Tokyo, Japan
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87
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Cohen S, Ke X, Liu Q, Fu Q, Majnik A, Lane R. Adverse early life environment increases hippocampal microglia abundance in conjunction with decreased neural stem cells in juvenile mice. Int J Dev Neurosci 2016; 55:56-65. [PMID: 27666383 DOI: 10.1016/j.ijdevneu.2016.09.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Revised: 09/20/2016] [Accepted: 09/21/2016] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Adverse maternal lifestyle resulting in adverse early life environment (AELE) increases risks for neuropsychiatric disorders in offspring. Neuropsychiatric disorders are associated with impaired neurogenesis and neuro-inflammation in the hippocampus (HP). Microglia are neuro-inflammatory cells in the brain that regulate neurogenesis via toll-like receptors (TLR). TLR-9 is implicated in neurogenesis inhibition and is responsible for stress-related inflammatory responses. We hypothesized that AELE would increase microglia cell count and increase TLR-9 expression in juvenile mouse HP. These increases in microglia cell count and TLR-9 expression would be associated with decrease neural stem cell count and neuronal cell count. METHODS We developed a mouse model of AELE combining Western diet and a stress environment. Stress environment consisted of random change from embryonic day 13 (E13) to E17 as well as static change in maternal environment from E13 to postnatal day 21(P21). At P21, we measured hippocampal cell numbers of microglia, neural stem cell and neuron, as well as hippocampal TLR-9 expression. RESULTS AELE significantly increased total microglia number and TLR-9 expression in the hippocampus. Concurrently, AELE significantly decreased neural stem cell and neuronal numbers. CONCLUSIONS AELE increased the neuro-inflammatory cellular response in the juvenile HP. We speculate that increased neuro-inflammatory responses may contribute to impaired neurogenesis seen in this model.
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Affiliation(s)
- Susan Cohen
- Division of Neonatology, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, United States.
| | - Xingrao Ke
- Division of Neonatology, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Qiuli Liu
- Division of Neonatology, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Qi Fu
- Division of Neonatology, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Amber Majnik
- Division of Neonatology, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Robert Lane
- Division of Neonatology, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, United States
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88
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Noguchi H, Kimura A, Murao N, Namihira M, Nakashima K. Prenatal deletion of DNA methyltransferase 1 in neural stem cells impairs neurogenesis and causes anxiety-like behavior in adulthood. NEUROGENESIS 2016; 3:e1232679. [PMID: 27844025 DOI: 10.1080/23262133.2016.1232679] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 08/30/2016] [Accepted: 08/31/2016] [Indexed: 12/25/2022]
Abstract
Despite recent advances in our understanding of epigenetic regulation of central nervous system development, little is known regarding the effects of epigenetic dysregulation on neurogenesis and brain function in adulthood. In the present study, we show that prenatal deletion of DNA methyltransferase 1 (Dnmt1) in neural stem cells results in impaired neurogenesis as well as increases in inflammatory features (e.g., elevated glial fibrillary acidic protein [GFAP] expression in astrocytes and increased numbers of microglia) in the adult mouse brain. Moreover, these mice exhibited anxiety-like behavior during an open-field test. These findings suggest that Dnmt1 plays a critical role in regulating neurogenesis and behavior in the developing brain and into adulthood.
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Affiliation(s)
- Hirofumi Noguchi
- Stem Cell Biology and Medicine, Department of Stem Cell Biology and Medicine, Graduate School of Medical Sciences, Kyushu University , Fukuoka, Japan
| | - Ayaka Kimura
- Stem Cell Biology and Medicine, Department of Stem Cell Biology and Medicine, Graduate School of Medical Sciences, Kyushu University , Fukuoka, Japan
| | - Naoya Murao
- Stem Cell Biology and Medicine, Department of Stem Cell Biology and Medicine, Graduate School of Medical Sciences, Kyushu University , Fukuoka, Japan
| | - Masakazu Namihira
- Molecular Neurophysiology Research Group, Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology , Ibaraki, Japan
| | - Kinichi Nakashima
- Stem Cell Biology and Medicine, Department of Stem Cell Biology and Medicine, Graduate School of Medical Sciences, Kyushu University , Fukuoka, Japan
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89
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Takamura R, Watamura N, Nikkuni M, Ohshima T. All-trans retinoic acid improved impaired proliferation of neural stem cells and suppressed microglial activation in the hippocampus in an Alzheimer's mouse model. J Neurosci Res 2016; 95:897-906. [PMID: 27448243 DOI: 10.1002/jnr.23843] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 06/28/2016] [Accepted: 06/28/2016] [Indexed: 01/21/2023]
Abstract
Alzheimer's disease (AD) is the most common neurodegenerative disorder characterized by cognitive impairment with neuronal loss. The number of patients suffering from AD has increased, but none of the present therapies stops the progressive symptoms in patients with AD. It has been reported that the activation of microglial cells induces harmful chronic inflammation, leading to neuronal death. Furthermore, the impairment of adult neurogenesis in the hippocampus has been observed earlier than amyloid plaque formation. Inflammatory response may lead to impaired adult neurogenesis in patients with AD. This study examines the relationship between adult neurogenesis and neuroinflammation using APPswe/PS1M146V/tauP301L (3 × Tg) mice. We observed a decline in the proliferation of neural stem cells and the occurrence of severe inflammation in the hippocampus of 3 × Tg mouse brains at 12 months of age. Previously, our research had shown an anti-inflammatory effect of all-trans retinoic acid (ATRA) in the 3 × Tg mouse brain. We found that ATRA has effects on the recovery of proliferative cells along with suppression of activated microglia in the hippocampus. These results suggest that the inhibition of microglial activation by ATRA leads to recovery of adult neurogenesis in the hippocampus in an AD mouse model. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Risa Takamura
- Laboratory for Molecular Brain Science, Department of Life Science and Medical Bioscience, Graduate School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
| | - Naoto Watamura
- Laboratory for Molecular Brain Science, Department of Life Science and Medical Bioscience, Graduate School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
| | - Miyu Nikkuni
- Laboratory for Molecular Brain Science, Department of Life Science and Medical Bioscience, Graduate School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
| | - Toshio Ohshima
- Laboratory for Molecular Brain Science, Department of Life Science and Medical Bioscience, Graduate School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
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90
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Luo C, Koyama R, Ikegaya Y. Microglia engulf viable newborn cells in the epileptic dentate gyrus. Glia 2016; 64:1508-17. [PMID: 27301702 DOI: 10.1002/glia.23018] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 05/24/2016] [Accepted: 05/26/2016] [Indexed: 12/12/2022]
Abstract
Microglia, which are the brain's resident immune cells, engulf dead neural progenitor cells during adult neurogenesis in the subgranular zone (SGZ) of the dentate gyrus (DG). The number of newborn cells in the SGZ increases significantly after status epilepticus (SE), but whether and how microglia regulate the number of newborn cells after SE remain unclear. Here, we show that microglia rapidly eliminate newborn cells after SE by primary phagocytosis, a process by which viable cells are engulfed, thereby regulating the number of newborn cells that are incorporated into the DG. The number of newborn cells in the DG was increased at 5 days after SE in the adult mouse brain but rapidly decreased to the control levels within a week. During this period, microglia in the DG were highly active and engulfed newborn cells. We found that the majority of engulfed newborn cells were caspase-negative viable cells. Finally, inactivation of microglia with minocycline maintained the increase in the number of newborn cells after SE. Furthermore, minocycline treatment after SE induced the emergence of hilar ectopic granule cells. Thus, our findings suggest that microglia may contribute to homeostasis of the dentate neurogenic niche by eliminating excess newborn cells after SE via primary phagocytosis. GLIA 2016;64:1508-1517.
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Affiliation(s)
- Cong Luo
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Japan
| | - Ryuta Koyama
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Japan
| | - Yuji Ikegaya
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Japan
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91
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Eyo UB, Murugan M, Wu LJ. Microglia-Neuron Communication in Epilepsy. Glia 2016; 65:5-18. [PMID: 27189853 DOI: 10.1002/glia.23006] [Citation(s) in RCA: 187] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 04/20/2016] [Accepted: 04/28/2016] [Indexed: 12/22/2022]
Abstract
Epilepsy has remained a significant social concern and financial burden globally. Current therapeutic strategies are based primarily on neurocentric mechanisms that have not proven successful in at least a third of patients, raising the need for novel alternative and complementary approaches. Recent evidence implicates glial cells and neuroinflammation in the pathogenesis of epilepsy with the promise of targeting these cells to complement existing strategies. Specifically, microglial involvement, as a major inflammatory cell in the epileptic brain, has been poorly studied. In this review, we highlight microglial reaction to experimental seizures, discuss microglial control of neuronal activities, and propose the functions of microglia during acute epileptic phenotypes, delayed neurodegeneration, and aberrant neurogenesis. Future research that would help fill in the current gaps in our knowledge includes epilepsy-induced alterations in basic microglial functions, neuro-microglial interactions during chronic epilepsy, and microglial contribution to developmental seizures. Studying the role of microglia in epilepsy could inform therapies to better alleviate the disease. GLIA 2016;65:5-18.
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Affiliation(s)
- Ukpong B Eyo
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey
| | - Madhuvika Murugan
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey
| | - Long-Jun Wu
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey
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92
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Ryan SM, Kelly ÁM. Exercise as a pro-cognitive, pro-neurogenic and anti-inflammatory intervention in transgenic mouse models of Alzheimer's disease. Ageing Res Rev 2016; 27:77-92. [PMID: 27039886 DOI: 10.1016/j.arr.2016.03.007] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 03/22/2016] [Accepted: 03/30/2016] [Indexed: 12/20/2022]
Abstract
It is now well established, at least in animal models, that exercise elicits potent pro-cognitive and pro-neurogenic effects. Alzheimer's disease (AD) is one of the leading causes of dementia and represents one of the greatest burdens on healthcare systems worldwide, with no effective treatment for the disease to date. Exercise presents a promising non-pharmacological option to potentially delay the onset of or slow down the progression of AD. Exercise interventions in mouse models of AD have been explored and have been found to reduce amyloid pathology and improve cognitive function. More recent studies have expanded the research question by investigating potential pro-neurogenic and anti-inflammatory effects of exercise. In this review we summarise studies that have examined exercise-mediated effects on AD pathology, cognitive function, hippocampal neurogenesis and neuroinflammation in transgenic mouse models of AD. Furthermore, we attempt to identify the optimum exercise conditions required to elicit the greatest benefits, taking into account age and pathology of the model, as well as type and duration of exercise.
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93
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Mapping of Variable DNA Methylation Across Multiple Cell Types Defines a Dynamic Regulatory Landscape of the Human Genome. G3-GENES GENOMES GENETICS 2016; 6:973-86. [PMID: 26888867 PMCID: PMC4825665 DOI: 10.1534/g3.115.025437] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
DNA methylation is an important epigenetic modification involved in many biological processes and diseases. Many studies have mapped DNA methylation changes associated with embryogenesis, cell differentiation, and cancer at a genome-wide scale. Our understanding of genome-wide DNA methylation changes in a developmental or disease-related context has been steadily growing. However, the investigation of which CpGs are variably methylated in different normal cell or tissue types is still limited. Here, we present an in-depth analysis of 54 single-CpG-resolution DNA methylomes of normal human cell types by integrating high-throughput sequencing-based methylation data. We found that the ratio of methylated to unmethylated CpGs is relatively constant regardless of cell type. However, which CpGs made up the unmethylated complement was cell-type specific. We categorized the 26,000,000 human autosomal CpGs based on their methylation levels across multiple cell types to identify variably methylated CpGs and found that 22.6% exhibited variable DNA methylation. These variably methylated CpGs formed 660,000 variably methylated regions (VMRs), encompassing 11% of the genome. By integrating a multitude of genomic data, we found that VMRs enrich for histone modifications indicative of enhancers, suggesting their role as regulatory elements marking cell type specificity. VMRs enriched for transcription factor binding sites in a tissue-dependent manner. Importantly, they enriched for GWAS variants, suggesting that VMRs could potentially be implicated in disease and complex traits. Taken together, our results highlight the link between CpG methylation variation, genetic variation, and disease risk for many human cell types.
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95
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A(H1N1) vaccination recruits T lymphocytes to the choroid plexus for the promotion of hippocampal neurogenesis and working memory in pregnant mice. Brain Behav Immun 2016; 53:72-83. [PMID: 26576725 DOI: 10.1016/j.bbi.2015.11.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Revised: 10/30/2015] [Accepted: 11/09/2015] [Indexed: 12/20/2022] Open
Abstract
We previously demonstrated that A(H1N1) influenza vaccine (AIV) promoted hippocampal neurogenesis and working memory in pregnant mice. However, the underlying mechanism of flu vaccination in neurogenesis and memory has remained unclear. In this study, we found that T lymphocytes were recruited from the periphery to the choroid plexus (CP) of the lateral and third (3rd) ventricles in pregnant mice vaccinated with AIV (Pre+AIV). Intracerebroventricular delivery of anti-TCR antibodies markedly decreased neurogenesis and the working memory of the Pre+AIV mice. Similarly, intravenous delivery of anti-CD4 antibodies to the periphery also down-regulated neurogenesis. Furthermore, AIV vaccination caused microglia to skew toward an M2-like phenotype (increased Arginase-1 and Ym1 mRNA levels), and elevated levels of brain-derived growth factor (BDNF) and insulin-like growth factor-1 (IGF-1) were found in the hippocampus, whereas these effects were offset by anti-TCR antibody treatment. Additionally, in the CP, the expression level of adhesion molecules and chemokines, which assist leukocytes in permeating into the brain, were also elevated after AIV vaccination of pregnant mice. Collectively, the results suggested that the infiltrative T lymphocytes in the CP contribute to the increase in hippocampal neurogenesis and working memory caused by flu vaccination, involving activation of the brain's CP, M2 microglial polarization and neurotrophic factor expression.
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97
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Seong KJ, Lee HG, Kook MS, Ko HM, Jung JY, Kim WJ. Epigallocatechin-3-gallate rescues LPS-impaired adult hippocampal neurogenesis through suppressing the TLR4-NF-κB signaling pathway in mice. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2015; 20:41-51. [PMID: 26807022 PMCID: PMC4722190 DOI: 10.4196/kjpp.2016.20.1.41] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 08/21/2015] [Accepted: 09/01/2015] [Indexed: 12/18/2022]
Abstract
Adult hippocampal dentate granule neurons are generated from neural stem cells (NSCs) in the mammalian brain, and the fate specification of adult NSCs is precisely controlled by the local niches and environment, such as the subventricular zone (SVZ), dentate gyrus (DG), and Toll-like receptors (TLRs). Epigallocatechin-3-gallate (EGCG) is the main polyphenolic flavonoid in green tea that has neuroprotective activities, but there is no clear understanding of the role of EGCG in adult neurogenesis in the DG after neuroinflammation. Here, we investigate the effect and the mechanism of EGCG on adult neurogenesis impaired by lipopolysaccharides (LPS). LPS-induced neuroinflammation inhibited adult neurogenesis by suppressing the proliferation and differentiation of neural stem cells in the DG, which was indicated by the decreased number of Bromodeoxyuridine (BrdU)-, Doublecortin (DCX)- and Neuronal Nuclei (NeuN)-positive cells. In addition, microglia were recruited with activatingTLR4-NF-κB signaling in the adult hippocampus by LPS injection. Treating LPS-injured mice with EGCG restored the proliferation and differentiation of NSCs in the DG, which were decreased by LPS, and EGCG treatment also ameliorated the apoptosis of NSCs. Moreover, pro-inflammatory cytokine production induced by LPS was attenuated by EGCG treatment through modulating the TLR4-NF-κB pathway. These results illustrate that EGCG has a beneficial effect on impaired adult neurogenesis caused by LPSinduced neuroinflammation, and it may be applicable as a therapeutic agent against neurodegenerative disorders caused by inflammation.
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Affiliation(s)
- Kyung-Joo Seong
- Dental Science Research Institute, School of Dentistry, Chonnam National University, Gwangju 61186, Korea.; Medical Research Center for Biomineralization Disorders, School of Dentistry, Chonnam National University, Gwangju 61186, Korea.; Department of Oral Physiology, School of Dentistry, Chonnam National University, Gwangju 61186, Korea
| | - Hyun-Gwan Lee
- Dental Science Research Institute, School of Dentistry, Chonnam National University, Gwangju 61186, Korea.; Medical Research Center for Biomineralization Disorders, School of Dentistry, Chonnam National University, Gwangju 61186, Korea.; Department of Oral Physiology, School of Dentistry, Chonnam National University, Gwangju 61186, Korea
| | - Min Suk Kook
- Dental Science Research Institute, School of Dentistry, Chonnam National University, Gwangju 61186, Korea.; Medical Research Center for Biomineralization Disorders, School of Dentistry, Chonnam National University, Gwangju 61186, Korea.; Department of Oral and Maxillofacial Surgery, School of Dentistry, Chonnam National University, Gwangju 61186, Korea
| | - Hyun-Mi Ko
- Department of Microbiology, Collage of Medicine, Seonam Universtity, Namwon 55724, Korea
| | - Ji-Yeon Jung
- Dental Science Research Institute, School of Dentistry, Chonnam National University, Gwangju 61186, Korea.; Medical Research Center for Biomineralization Disorders, School of Dentistry, Chonnam National University, Gwangju 61186, Korea.; Department of Oral Physiology, School of Dentistry, Chonnam National University, Gwangju 61186, Korea
| | - Won-Jae Kim
- Dental Science Research Institute, School of Dentistry, Chonnam National University, Gwangju 61186, Korea.; Medical Research Center for Biomineralization Disorders, School of Dentistry, Chonnam National University, Gwangju 61186, Korea.; Department of Oral Physiology, School of Dentistry, Chonnam National University, Gwangju 61186, Korea
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98
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Reduced Adult Hippocampal Neurogenesis and Cognitive Impairments following Prenatal Treatment of the Antiepileptic Drug Valproic Acid. Stem Cell Reports 2015; 5:996-1009. [PMID: 26677766 PMCID: PMC4682151 DOI: 10.1016/j.stemcr.2015.10.012] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Revised: 10/22/2015] [Accepted: 10/23/2015] [Indexed: 12/02/2022] Open
Abstract
Prenatal exposure to valproic acid (VPA), an established antiepileptic drug, has been reported to impair postnatal cognitive function in children born to VPA-treated epileptic mothers. However, how these defects arise and how they can be overcome remain unknown. Using mice, we found that comparable postnatal cognitive functional impairment is very likely correlated to the untimely enhancement of embryonic neurogenesis, which led to depletion of the neural precursor cell pool and consequently a decreased level of adult neurogenesis in the hippocampus. Moreover, hippocampal neurons in the offspring of VPA-treated mice showed abnormal morphology and activity. Surprisingly, these impairments could be ameliorated by voluntary running. Our study suggests that although prenatal exposure to antiepileptic drugs such as VPA may have detrimental effects that persist until adulthood, these effects may be offset by a simple physical activity such as running. Prenatal VPA treatment caused an untimely enhancement of embryonic neurogenesis Prenatal VPA treatment has the long-term effect of impairing adult neurogenesis Reduced level of adult neurogenesis is associated with cognitive functional impairments Voluntary running can ameliorate the persistent detrimental effects caused by VPA
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99
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Matsuda T, Nakashima K. Bidirectional communication between the innate immune and nervous systems for homeostatic neurogenesis in the adult hippocampus. NEUROGENESIS 2015; 2:e1081714. [PMID: 27604264 PMCID: PMC4973595 DOI: 10.1080/23262133.2015.1081714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 08/03/2015] [Accepted: 08/04/2015] [Indexed: 10/25/2022]
Abstract
A population of proliferating neural stem/progenitor cells located in the subgranular zone of the adult hippocampal dentate gyrus (DG) gives rise to new neurons continuously throughout life, and this process is referred to as adult hippocampal neurogenesis. To date, it has generally been accepted that impairments of adult hippocampal neurogenesis resulting from pathological conditions such as stress, ischemia and epilepsy lead to deficits in hippocampus-dependent learning and memory tasks. Recently, we have discovered that microglia, the major immune cells in the brain, attenuate seizure-induced aberrant hippocampal neurogenesis to withstand cognitive decline and recurrent seizure. In that study, we further showed that Toll-like receptor 9, known as a pathogen-sensing receptor for innate immune system activation, recognizes self-DNA derived from degenerating neurons to induce TNF-α production in the microglia after seizure, resulting in inhibition of seizure-induced aberrant neurogenesis. Our findings provide new evidence that interaction between the innate immune and nervous systems ensures homeostatic neurogenesis in the adult hippocampus and should pave the way for the development of new therapeutic strategies for neurological diseases including epilepsy.
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Affiliation(s)
- Taito Matsuda
- Department of Stem Cell Biology and Medicine; Graduate School of Medical Sciences; Kyushu University ; Fukuoka, Japan
| | - Kinichi Nakashima
- Department of Stem Cell Biology and Medicine; Graduate School of Medical Sciences; Kyushu University ; Fukuoka, Japan
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