351
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Baune BT, Wiede F, Braun A, Golledge J, Arolt V, Koerner H. Cognitive dysfunction in mice deficient for TNF- and its receptors. Am J Med Genet B Neuropsychiatr Genet 2008; 147B:1056-64. [PMID: 18286589 DOI: 10.1002/ajmg.b.30712] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Recent evidence suggests a role for tumor necrosis factor alpha (TNF) in the functioning of the central nervous system (CNS). The aim of this work was to examine the effect of a deficiency of TNF (TNF(-/-)) and its main receptors (TNF-R1(-/-) and TNF-R2(-/-)) on cognitive function. A standardized survey on cognition-like behavior assessing learning and retention, spatial learning/memory, cognitive flexibility, and learning effectiveness was used in B6.WT and B6.TNF gene targeted mice strains (B6.wild-type, B6.TNF(-/-), B6.TNF-R1(-/-), B6.TNF-R2(-/-) mice). All studied mice strains demonstrated successful exploration and learning processes during the training phases of the tests, which made the specific cognition-like tests valid in these mice strains. In the specific cognition-like tests, the B6.TNF(-/-) mice demonstrated significantly poorer learning and retention in the novel object test compared to B6.WT, B6.TNF-R1(-/-) and B6.TNF-R2(-/-) mice. In addition, spatial learning and learning effectiveness were significantly poorer in B6.TNF(-/-) mice compared to B6.WT mice. Moreover, the moderately impaired cognitive performance with similar degrees in B6.TNF-R1(-/-) or B6.TNF-R2(-/-) mice was generally better than in TNF(-/-) mice but also poorer than in B6.WT mice. While the absence of TNF was correlated with poor cognitive functioning, the deletion of both TNF-receptors was involved in partially reduced cognitive functioning. Low-levels of TNF under non-inflammatory immune conditions appear essential for normal cognitive function. TNF displays an interesting candidate gene for cognitive function. Translational research is required to investigate associations between genetic variants of TNF and cognitive function in healthy subjects and neuropsychiatric samples.
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Affiliation(s)
- Bernhard T Baune
- Psychogenetics Research Unit, School of Medicine and Comparative Genomics Centre, James Cook University, Townsville, Australia.
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352
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Wellen J, Walter J, Jangouk P, Hartung HP, Dihné M. Neural precursor cells as a novel target for interferon-beta. Neuropharmacology 2008; 56:386-98. [PMID: 18930745 DOI: 10.1016/j.neuropharm.2008.09.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2008] [Revised: 08/05/2008] [Accepted: 09/11/2008] [Indexed: 02/07/2023]
Abstract
The immunomodulating agent interferon-beta (IFNbeta) is administered therapeutically in several autoimmune diseases and endogenously released by immune cells during diverse infections. As in recent years a variety of pro- and anti-inflammatory substances were shown to influence significantly neural precursor cells that are implicated in a variety of regenerative mechanisms but also in tumor growth, we studied a possible effect of IFNbeta on neural precursor cells derived from murine embryonic day 14 neurospheres. First, we demonstrated that interferon type-I receptors are expressed on neural precursor cells and that these cells respond to IFNbeta treatment by up-regulating IFNbeta inducible genes including Myxovirus 1 and viperin. Furthermore, we could show for the first time that IFNbeta treatment significantly inhibited the proliferation of neural precursor cells possibly through induction of p21, a cyclin-dependent kinase inhibitor. IFNbeta did not exert cytotoxic or neuroprotective effects and we could not see effects on the differentiation of neural precursor cells into total amounts of neurons, astrocytes or oligodendrocytes. However, we found that IFNbeta markedly diminished neurite outgrowth and neuronal maturation of neural precursor-derived neurons.
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Affiliation(s)
- Jennifer Wellen
- Department of Neurology, Heinrich-Heine University, Moorenstr. 5, 40225 Düsseldorf, Germany
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353
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Iosif RE, Ahlenius H, Ekdahl CT, Darsalia V, Thored P, Jovinge S, Kokaia Z, Lindvall O. Suppression of stroke-induced progenitor proliferation in adult subventricular zone by tumor necrosis factor receptor 1. J Cereb Blood Flow Metab 2008; 28:1574-87. [PMID: 18493257 DOI: 10.1038/jcbfm.2008.47] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Stroke induced by middle cerebral artery occlusion leads to transiently increased progenitor proliferation in the subventricular zone (SVZ) and long-lasting striatal neurogenesis in adult rodents. Tumor necrosis factor-alpha (TNF-alpha) is upregulated in stroke-damaged brain. Whether TNF-alpha and its receptors influence SVZ progenitor proliferation after stroke is unclear. Here we show that the increased proliferation 1 week after stroke occurred concomitantly with elevated microglia numbers and TNF-alpha and TNF receptor-1 (TNF-R1) gene expression in the SVZ of wild-type mice. TNF receptor-1 was expressed on sorted SVZ progenitor cells from nestin-green fluorescent protein reporter mice. In animals lacking TNF-R1, stroke-induced SVZ cell proliferation and neuroblast formation were enhanced. In contrast, deletion of TNF-R1 did not alter basal or status epilepticus-stimulated cell proliferation in SVZ. Addition of TNF-alpha reduced the size and numbers of SVZ neurospheres through a TNF-R1-dependent mechanism without affecting cell survival. Our results provide the first evidence that TNF-R1 is a negative regulator of stroke-induced SVZ progenitor proliferation. Blockade of TNF-R1 signaling might be a novel strategy to promote the proliferative response in SVZ after stroke.
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Affiliation(s)
- Robert E Iosif
- Laboratory of Neurogenesis and Cell Therapy, Section of Restorative Neurology, Wallenberg Neuroscience Center, University Hospital, Lund, Sweden
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354
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Chen Z, Palmer TD. Cellular repair of CNS disorders: an immunological perspective. Hum Mol Genet 2008; 17:R84-92. [PMID: 18632702 DOI: 10.1093/hmg/ddn104] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Cellular repair is a promising strategy for treating central nervous system (CNS) disorders. Several strategies have been contemplated including replacement of neurons or glia that have been lost due to injury or disease, use of cellular grafts to modify or augment the functions of remaining neurons and/or use of cellular grafts to protect neural tissue by local delivery of growth or trophic factors. Depending on the specific disease target, there may be one or many cell types that could be considered for therapy. In each case, an additional variable must be considered--the role of the immune system in both the injury process itself and in the response to incoming cells. Cellular transplants can be roughly categorized into autografts, allografts and xenografts. Despite the immunological privilege of the CNS, allografts and xenografts can elicit activation of the innate and adaptive immune system. In this article, we evaluate the various effects that immune cells and signals may have on the survival, proliferation, differentiation and migration/integration of transplanted cells in therapeutic approaches to CNS injury and disease.
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Affiliation(s)
- Zhiguo Chen
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA 94305, USA
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355
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Peng H, Whitney N, Wu Y, Tian C, Dou H, Zhou Y, Zheng J. HIV-1-infected and/or immune-activated macrophage-secreted TNF-alpha affects human fetal cortical neural progenitor cell proliferation and differentiation. Glia 2008; 56:903-16. [PMID: 18383342 DOI: 10.1002/glia.20665] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Neurogenesis, tied to the proliferation, migration and differentiation of neural progenitor cells (NPC) is affected during neurodegenerative diseases, but how neurogenesis is affected during HIV-1 associated dementia (HAD) has not been fully addressed. Here we test the hypothesis that HIV-1-infected and/or immune-activated brain macrophages affect NPC proliferation and differentiation through the regulation of cytokines. We showed that human monocyte-derived macrophages (MDM) conditioned medium (MCM) induces a dose dependent increase in NPC proliferation. Conditioned media from lipopolysaccharide (LPS)-activated MDM (LPS-MCM) or HIV-infected MCM (HIV-MCM) induced a profound increase in NPC proliferation. HIV-infected and LPS-activated MCM (HIV+LPS-MCM) induced the most robust increase in NPC proliferation. Moreover, LPS-MCM and HIV+LPS-MCM decreased beta-III-tubulin and increased GFAP expression, demonstrating an induction of gliogenesis and inhibition of neurogenesis. The increase of NPC proliferation and gliogenesis correlated with increases in production of TNF-alpha by infected/activated MDM. Although both IL-1beta and TNF-alpha induced NPC proliferation and gliogenesis, these effects were only partially abrogated by soluble TNF-alpha receptors R1 and R2 (TNF-R1R2), but not by the IL-1 receptor antagonist (IL-1ra). This indicated that the HIV-1-infected/LPS-activated MCM-mediated effects were, in part, through TNF-alpha. These observations were confirmed in severe combined immunodeficient (SCID) mice with HIV-1 encephalitis (HIVE). In these HIVE mice, NPC injected with HIV-infected MDM showed more astrocyte differentiation and less neuronal differentiation compared to NPC injection alone. These observations demonstrated that HIV-1-infected and immune-activated MDM could affect neurogenesis through induction of NPC proliferation, inhibition of neurogenesis, and activation of gliogenesis.
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Affiliation(s)
- Hui Peng
- Laboratory of Neurotoxicology, University of Nebraska Medical Center, Omaha, Nebraska 68190-5880, USA
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356
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Brain inflammation and adult neurogenesis: the dual role of microglia. Neuroscience 2008; 158:1021-9. [PMID: 18662748 DOI: 10.1016/j.neuroscience.2008.06.052] [Citation(s) in RCA: 568] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2008] [Revised: 06/18/2008] [Accepted: 06/20/2008] [Indexed: 12/16/2022]
Abstract
In the adult mammalian brain, neurogenesis from neural stem/progenitor cells continues in two regions: the subgranular zone in the dentate gyrus and the subventricular zone lining the lateral ventricles. The generated neuroblasts migrate to their appropriate location and differentiate to mature granule cells and olfactory bulb interneurons, respectively. Following injury such as stroke, neuroblasts generated in the subventricular zone migrate also into areas which are not normally neurogenic, e.g. striatum and cerebral cortex. In the initial studies in rodents, brain inflammation and microglia activation were found to be detrimental for the survival of the new hippocampal neurons early after they had been born. The role of inflammation for adult neurogenesis has, however, turned out to be much more complex. Recent experimental evidence indicates that microglia under certain circumstances can be beneficial and support the different steps in neurogenesis, progenitor proliferation, survival, migration, and differentiation. Here we summarize the current knowledge on the role of inflammation and in particular of microglia in adult neurogenesis in the intact and injured mammalian brain. We conclude that microglia activation, as an indicator of inflammation, is not pro- or antineurogenic per se but the net outcome is dependent on the balance between secreted molecules with pro- and antiinflammatory action.
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357
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Rubio-Araiz A, Arévalo-Martín Á, Gómez-Torres O, Navarro-Galve B, García-Ovejero D, Suetterlin P, Sánchez-Heras E, Molina-Holgado E, Molina-Holgado F. The endocannabinoid system modulates a transient TNF pathway that induces neural stem cell proliferation. Mol Cell Neurosci 2008; 38:374-80. [DOI: 10.1016/j.mcn.2008.03.010] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2007] [Revised: 03/14/2008] [Accepted: 03/28/2008] [Indexed: 12/31/2022] Open
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358
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Das S, Basu A. Inflammation: a new candidate in modulating adult neurogenesis. J Neurosci Res 2008; 86:1199-208. [PMID: 18058947 DOI: 10.1002/jnr.21585] [Citation(s) in RCA: 166] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Any pathological perturbation to the brain provokes a cascade of molecular and cellular events, which manifests in the form of microglial activation and release of various proinflammatory molecules. This eventually culminates in a profound neuroinflammatory reaction that characterizes the brain's response to stress, injury, or infection. The inflammatory cascade is an attempt by the system to eliminate the challenge imposed on the brain, clear the system of the dead and damaged neurons, and rescue the normal functioning of this vital organ. However, during the process of microglial activation, the proinflammatory mediators released exert certain detrimental effects, and neural stem cells and progenitor cells are likely to be affected. Here we review how the proliferation, maturation, and migration of the neural stem cells are modulated under such an inflammatory condition. The fate of the noncommitted neural stem cells and its differentiation potency are often under strict regulation, and these proinflammatory mediators seem to disrupt this critical balance and finely tune the neurogenesis pattern in the two niches of neurogenesis, the subventricular zone and the subgranular zone of the hippocampus. Moreover, the migration ability of these stem cells, which is important for localization to the proper site, is also affected in a major way by the chemokines released following inflammation.
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Affiliation(s)
- Sulagna Das
- National Brain Research Centre, Manesar, Haryana, India.
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359
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Kato T, Mizoguchi Y, Monji A, Horikawa H, Suzuki SO, Seki Y, Iwaki T, Hashioka S, Kanba S. Inhibitory effects of aripiprazole on interferon--induced microglial activation via intracellular Ca2+regulationin vitro. J Neurochem 2008; 106:815-25. [DOI: 10.1111/j.1471-4159.2008.05435.x] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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360
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Bernardino L, Agasse F, Silva B, Ferreira R, Grade S, Malva JO. Tumor necrosis factor-alpha modulates survival, proliferation, and neuronal differentiation in neonatal subventricular zone cell cultures. Stem Cells 2008; 26:2361-71. [PMID: 18583543 DOI: 10.1634/stemcells.2007-0914] [Citation(s) in RCA: 160] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Tumor necrosis factor (TNF)-alpha has been reported to modulate brain injury, but remarkably, little is known about its effects on neurogenesis. We report that TNF-alpha strongly influences survival, proliferation, and neuronal differentiation in cultured subventricular zone (SVZ) neural stem/progenitor cells derived from the neonatal P1-3 C57BL/6 mice. By using single-cell calcium imaging, we developed a method, based on cellular response to KCl and/or histamine, that allows the functional evaluation of neuronal differentiation. Exposure of SVZ cultures to 1 and 10 ng/ml mouse or 1 ng/ml human recombinant TNF-alpha resulted in increased differentiation of cells displaying a neuronal-like profile of [Ca2+](i) responses, compared with the predominant profile of immature cells observed in control, nontreated cultures. Moreover, by using neutralizing antibodies for each TNF-alpha receptor, we found that the proneurogenic effect of 1 ng/ml TNF-alpha is mediated via tumor necrosis factor receptor 1 activation. Accordingly, the percentage of neuronal nuclear protein-positive neurons was increased following exposure to mouse TNF-alpha. Interestingly, exposure of SVZ cultures to 1 ng/ml TNF-alpha induced cell proliferation, whereas 10 and 100 ng/ml TNF-alpha induced apoptotic cell death. Moreover, we found that exposure of SVZ cells to TNF-alpha for 15 minutes or 6 hours caused an increase in the phospho-stress-activated protein kinase/c-Jun N-terminal kinase immunoreactivity initially in the nucleus and then in growing axons, colocalizing with tau, consistent with axonogenesis. Taken together, these results show that TNF-alpha induces neurogenesis in neonatal SVZ cell cultures of mice. TNF-alpha, a proinflammatory cytokine and a proneurogenic factor, may play a central role in promoting neurogenesis and brain repair in response to brain injury and infection.
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Affiliation(s)
- Liliana Bernardino
- Center for Neuroscience and Cell Biology, Institute of Biochemistry, Faculty of Medicine, University of Coimbra, 3004-504 Coimbra, Portugal
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361
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Baron R, Nemirovsky A, Harpaz I, Cohen H, Owens T, Monsonego A. IFN‐γ enhances neurogenesis in wild‐type mice and in a mouse model of Alzheimer's disease. FASEB J 2008; 22:2843-52. [DOI: 10.1096/fj.08-105866] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Rona Baron
- The Shraga Segal Department of Microbiology and ImmunologyBen-Gurion University of the NegevBeer-ShevaIsrael
- The National Institute of Biotechnology in the NegevBen-Gurion University of the NegevBeer-ShevaIsrael
| | - Anna Nemirovsky
- The Shraga Segal Department of Microbiology and ImmunologyBen-Gurion University of the NegevBeer-ShevaIsrael
- The National Institute of Biotechnology in the NegevBen-Gurion University of the NegevBeer-ShevaIsrael
| | - Idan Harpaz
- The Shraga Segal Department of Microbiology and ImmunologyBen-Gurion University of the NegevBeer-ShevaIsrael
- Ministry of Health, Mental Health Center, Anxiety and Stress Research Unit, Faculty of Health SciencesBen-Gurion University of the NegevBeer-ShevaIsrael
- The National Institute of Biotechnology in the NegevBen-Gurion University of the NegevBeer-ShevaIsrael
| | - Hagit Cohen
- Ministry of Health, Mental Health Center, Anxiety and Stress Research Unit, Faculty of Health SciencesBen-Gurion University of the NegevBeer-ShevaIsrael
| | - Trevor Owens
- Medical Biotechnology CenterUniversity of Southern DenmarkOdenseDenmark
| | - Alon Monsonego
- The Shraga Segal Department of Microbiology and ImmunologyBen-Gurion University of the NegevBeer-ShevaIsrael
- The National Institute of Biotechnology in the NegevBen-Gurion University of the NegevBeer-ShevaIsrael
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362
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Endres M, Engelhardt B, Koistinaho J, Lindvall O, Meairs S, Mohr JP, Planas A, Rothwell N, Schwaninger M, Schwab ME, Vivien D, Wieloch T, Dirnagl U. Improving outcome after stroke: overcoming the translational roadblock. Cerebrovasc Dis 2008; 25:268-78. [PMID: 18292653 DOI: 10.1159/000118039] [Citation(s) in RCA: 205] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2007] [Accepted: 07/09/2007] [Indexed: 12/31/2022] Open
Abstract
Stroke poses a massive burden of disease, yet we have few effective therapies. The paucity of therapeutic options stands contrary to intensive research efforts. The failure of these past investments demands a thorough re-examination of the pathophysiology of ischaemic brain injury. Several critical areas hold the key to overcoming the translational roadblock: (1) vascular occlusion: current recanalization strategies have limited effectiveness and may have serious side effects; (2) complexity of stroke pathobiology: therapy must acknowledge the 'Janus-faced' nature of many stroke targets and must identify endogenous neuroprotective and repair mechanisms; (3) inflammation and brain-immune-system interaction: inflammation contributes to lesion expansion, but is also instrumental in lesion containment and repair; stroke outcome is modulated by the interaction of the injured brain with the immune system; (4) regeneration: the potential of the brain for reorganization, plasticity and repair after injury is much greater than previously thought; (5) confounding factors, long-term outcome and predictive modelling. These 5 areas are linked on all levels and therefore need to be tackled by an integrative approach and innovative therapeutic strategies.
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Affiliation(s)
- Matthias Endres
- Department of Neurology, Center for Stroke Research, Charité, Berlin, Germany
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363
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Taoufik E, Tseveleki V, Euagelidou M, Emmanouil M, Voulgari-Kokota A, Haralambous S, Probert L. Positive and Negative Implications of Tumor Necrosis Factor Neutralization for the Pathogenesis of Multiple Sclerosis. NEURODEGENER DIS 2007; 5:32-7. [DOI: 10.1159/000109936] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2006] [Accepted: 01/16/2007] [Indexed: 11/19/2022] Open
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364
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Gemma C, Bachstetter AD, Cole MJ, Fister M, Hudson C, Bickford PC. Blockade of caspase-1 increases neurogenesis in the aged hippocampus. Eur J Neurosci 2007; 26:2795-803. [DOI: 10.1111/j.1460-9568.2007.05875.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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365
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Schmidt HD, Duman RS. The role of neurotrophic factors in adult hippocampal neurogenesis, antidepressant treatments and animal models of depressive-like behavior. Behav Pharmacol 2007; 18:391-418. [PMID: 17762509 DOI: 10.1097/fbp.0b013e3282ee2aa8] [Citation(s) in RCA: 493] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Major depressive disorder (MDD) is characterized by structural and neurochemical changes in limbic structures, including the hippocampus, that regulate mood and cognitive functions. Hippocampal atrophy is observed in patients with depression and this effect is blocked or reversed by antidepressant treatments. Brain-derived neurotrophic factor and other neurotrophic/growth factors are decreased in postmortem hippocampal tissue from suicide victims, which suggests that altered trophic support could contribute to the pathophysiology of MDD. Preclinical studies demonstrate that exposure to stress leads to atrophy and cell loss in the hippocampus as well as decreased expression of neurotrophic/growth factors, and that antidepressant administration reverses or blocks the effects of stress. Accumulating evidence suggests that altered neurogenesis in the adult hippocampus mediates the action of antidepressants. Chronic antidepressant administration upregulates neurogenesis in the adult hippocampus and this cellular response is required for the effects of antidepressants in certain animal models of depression. Here, we review cellular (e.g. adult neurogenesis) and behavioral studies that support the neurotrophic/neurogenic hypothesis of depression and antidepressant action. Aberrant regulation of neuronal plasticity, including neurogenesis, in the hippocampus and other limbic nuclei may result in maladaptive changes in neural networks that underlie the pathophysiology of MDD.
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Affiliation(s)
- Heath D Schmidt
- Division of Molecular Psychiatry, Abraham Ribicoff Research Facilities, Department of Psychiatry and Pharmacology, Yale University School of Medicine, New Haven, Connecticut, USA
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366
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Rolls A, Shechter R, London A, Ziv Y, Ronen A, Levy R, Schwartz M. Toll-like receptors modulate adult hippocampal neurogenesis. Nat Cell Biol 2007; 9:1081-8. [PMID: 17704767 DOI: 10.1038/ncb1629] [Citation(s) in RCA: 458] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2007] [Accepted: 07/16/2007] [Indexed: 12/19/2022]
Abstract
Neurogenesis - the formation of new neurons in the adult brain - is considered to be one of the mechanisms by which the brain maintains its lifelong plasticity in response to extrinsic and intrinsic changes. The mechanisms underlying the regulation of neurogenesis are largely unknown. Here, we show that Toll-like receptors (TLRs), a family of highly conserved pattern-recognizing receptors involved in neural system development in Drosophila and innate immune activity in mammals, regulate adult hippocampal neurogenesis. We show that TLR2 and TLR4 are found on adult neural stem/progenitor cells (NPCs) and have distinct and opposing functions in NPC proliferation and differentiation both in vitro and in vivo. TLR2 deficiency in mice impaired hippocampal neurogenesis, whereas the absence of TLR4 resulted in enhanced proliferation and neuronal differentiation. In vitro studies further indicated that TLR2 and TLR4 directly modulated self-renewal and the cell-fate decision of NPCs. The activation of TLRs on the NPCs was mediated via MyD88 and induced PKCalpha/beta-dependent activation of the NF-kappaB signalling pathway. Thus, our study identified TLRs as players in adult neurogenesis and emphasizes their specified and diverse role in cell renewal.
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Affiliation(s)
- Asya Rolls
- Department of Neurobiology, The Weizmann Institute of Science, 76100 Rehovot, Israel
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367
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Hoffmann O, Mahrhofer C, Rueter N, Freyer D, Bert B, Fink H, Weber JR. Pneumococcal cell wall-induced meningitis impairs adult hippocampal neurogenesis. Infect Immun 2007; 75:4289-97. [PMID: 17591796 PMCID: PMC1951165 DOI: 10.1128/iai.01679-06] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Bacterial meningitis is a major infectious cause of neuronal degeneration in the hippocampus. Neurogenesis, a continuous process in the adult hippocampus, could ameliorate such loss. Yet the high rate of sequelae from meningitis suggests that this repair mechanism is inefficient. Here we used a mouse model of nonreplicative bacterial meningitis to determine the impact of transient intracranial inflammation on adult neurogenesis. Experimental meningitis resulted in a net loss of neurons, diminished volume, and impaired neurogenesis in the dentate gyrus for weeks following recovery from the insult. Inducible nitric oxide synthase (iNOS) immunoreactivity was prominent in microglia in nonproliferating areas of the dentate gyrus and hilus region after meningitis induction. Treatment with the specific iNOS inhibitor N6-(1-iminoethyl)-L-lysine restored neurogenesis in experimental meningitis. These data suggest that local central nervous system inflammation in and of itself suppresses adult neurogenesis by affecting both proliferation and neuronal differentiation. Repair of cognitive dysfunction following meningitis could be improved by intervention to interrupt these actively suppressive effects.
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Affiliation(s)
- Olaf Hoffmann
- Department of Cell Biology, Center for Anatomy, Charité--Universitaetsmedizin Berlin, Schumannstr. 20/21, 10117 Berlin, Germany
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368
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Schölzke MN, Schwaninger M. Transcriptional regulation of neurogenesis: potential mechanisms in cerebral ischemia. J Mol Med (Berl) 2007; 85:577-88. [PMID: 17429598 DOI: 10.1007/s00109-007-0196-z] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2006] [Revised: 02/27/2007] [Accepted: 03/20/2007] [Indexed: 12/11/2022]
Abstract
Recent data provides evidence that new neurons are born in cerebral ischemia. Although ultimate evidence for their functional importance is lacking, correlational data suggest that they contribute to recovery. Therefore, the underlying mechanisms of neurogenesis are interesting as a basis for pharmacological enhancement of the phenomenon. Neurogenesis is a multistep process that includes proliferation of precursor cells, migration of the newborn cells to the site of lesion, differentiation, integration into neuronal circuits, and survival. All these steps rely on gene transcription. However, only preliminary data about the specific transcriptional control of neurogenesis in cerebral ischemia have been obtained so far. To promote this investigation, we review currently available information on six pathways (Notch, Wnt/beta-catenin, NF-kappaB, signal transducers and activators of transcription (STA) 3, HIF-1, and cyclic AMP response element-binding protein [CREB]) that have been shown to regulate transcription in neurogenesis and that have been implicated in cerebral ischemia. With the exception of CREB, direct involvement in postischemic neurogenesis is quite conjectural and much more must be learned to draw practical conclusions.
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Affiliation(s)
- Marion N Schölzke
- Department of Neurology, University of Heidelberg, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany
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369
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Kim SJ, Son TG, Kim K, Park HR, Mattson MP, Lee J. Interferon-gamma promotes differentiation of neural progenitor cells via the JNK pathway. Neurochem Res 2007; 32:1399-406. [PMID: 17415631 DOI: 10.1007/s11064-007-9323-z] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2007] [Accepted: 02/27/2007] [Indexed: 12/22/2022]
Abstract
It has been reported that interferon-gamma (IFN-gamma) facilitates differentiation of PC-12 cells and murine adult neural stem cells. Here we show that IFN-gamma promotes the differentiation of C17.2 neural progenitor cells (NPC) into a neuronal phenotype characterized by neurite outgrowth and the expression of the neuronal marker protein beta-III tubulin. IFN-gamma induced an increase in the activity c-jun N-terminal kinase (JNK) without affecting activities of extracellular signal-regulated kinases (ERKs 1 and 2). An inhibitor of JNK blocked the ability of IFN-gamma to promote differentiation of NPC into neurons, whereas an inhibitor of ERKs 1 and 2 did not. Our findings show that the pro-inflammatory cytokine, IFN-gamma has the potential to stimulate neurogenesis, suggesting roles for this cytokine in development and repair of the nervous system.
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Affiliation(s)
- So Jung Kim
- Department of Pharmacy, College of Pharmacy and Research Institute for Drug Development, Longevity Life Science and Technology Institutes, Pusan National University, Geumjeong-gu, Busan, Korea
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Gosselin D, Rivest S. Role of IL-1 and TNF in the brain: twenty years of progress on a Dr. Jekyll/Mr. Hyde duality of the innate immune system. Brain Behav Immun 2007; 21:281-9. [PMID: 17275255 DOI: 10.1016/j.bbi.2006.12.004] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2006] [Revised: 12/05/2006] [Accepted: 12/06/2006] [Indexed: 11/26/2022] Open
Abstract
The immune-privileged status of the central nervous system (CNS) has changed quite dramatically during the past two decades. Leukocytes have the ability to infiltrate the CNS and cytokines are produced by resident cells, especially during injuries and diseases. Although the cellular source and role of these immune ligands are better known, their exact contribution to brain protection, repair or diseases still remains highly debated today. The ultimate fate of the immune reaction depends on the cytokines involved and the experimental models. It is now generally accepted that microglia play a central role in this response, at least for the production of cytokines participating in the innate immune system. As macrophages, resident microglia produce numerous cytokines and two of them have been largely studied since the beginning of this field of research. Twenty years ago, interleukin 1 (IL-1) and tumor-necrosis factor (TNF) were cloned and recombinant forms were used to investigate their functions ranging from normal neurophysiological responses to pathological conditions. This review presents the history of these two cytokines during immune responses in the brain and where we are now two decades later.
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Affiliation(s)
- David Gosselin
- Laboratory of Molecular Endocrinology, CHUL Research Center and Department of Anatomy and Physiology, Laval University 2705, Boulevard Laurier, Que., Canada G1V 4G2
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Jakubs K, Nanobashvili A, Bonde S, Ekdahl CT, Kokaia Z, Kokaia M, Lindvall O. Environment matters: synaptic properties of neurons born in the epileptic adult brain develop to reduce excitability. Neuron 2007; 52:1047-59. [PMID: 17178407 DOI: 10.1016/j.neuron.2006.11.004] [Citation(s) in RCA: 210] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2006] [Revised: 09/20/2006] [Accepted: 11/06/2006] [Indexed: 11/24/2022]
Abstract
Neural progenitors in the adult dentate gyrus continuously produce new functional granule cells. Here we used whole-cell patch-clamp recordings to explore whether a pathological environment influences synaptic properties of new granule cells labeled with a GFP-retroviral vector. Rats were exposed to a physiological stimulus, i.e., running, or a brain insult, i.e., status epilepticus, which gave rise to neuronal death, inflammation, and chronic seizures. Granule cells formed after these stimuli exhibited similar intrinsic membrane properties. However, the new neurons born into the pathological environment differed with respect to synaptic drive and short-term plasticity of both excitatory and inhibitory afferents. The new granule cells formed in the epileptic brain exhibited functional connectivity consistent with reduced excitability. We demonstrate a high degree of plasticity in synaptic inputs to adult-born new neurons, which could act to mitigate pathological brain function.
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Affiliation(s)
- Katherine Jakubs
- Laboratory of Neurogenesis and Cell Therapy, Section of Restorative Neurology, Wallenberg Neuroscience Center, University Hospital, SE-221 84 Lund, Sweden
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