| 11. |
- Rahpeymai Bogestål, Yalda, 1977, et al.
(author)
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Signaling through C5aR is not involved in basal neurogenesis.
- 2007
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In: Journal of neuroscience research. - : Wiley. - 0360-4012 .- 1097-4547. ; 85:13, s. 2892-7
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Journal article (peer-reviewed)abstract
- The complement system, an important part of the innate immune system, provides protection against invading pathogens, in part through its proinflammatory activities. Although most complement proteins are synthesized locally in the brain and the relevant complement receptors are expressed on resident brain cells, little is known about brain-specific role(s) of the complement system. C3a and C5a, complement-derived peptides with anaphylatoxic properties, have been implicated in noninflammatory functions, such as tissue regeneration and neuroprotection. Recently, we have shown that signaling through C3a receptor (C3aR) is involved in the regulation of neurogenesis. In the present study, we assessed basal neurogenesis in mice lacking C5a receptor (C5aR(-/-)) and mice expressing C3a and C5a, respectively in the CNS under the control of glial fibrillary acidic protein (GFAP) promoter (C3a/GFAP and C5a/GFAP, respectively) and thus without the requirement for complement activation. We did not observe any difference among C5aR(-/-), C3a/GFAP and C5a/GFAP mice and their respective controls in the number of newly formed neuroblasts and newly formed neurons in the subventricular zone (SVZ) of lateral ventricles and hippocampal dentate gyrus, the two neurogenic niches in the adult brain, or the olfactory bulb, the final destination of new neurons formed in the SVZ. Our results indicate that signaling through C5aR is not involved in basal neurogenesis in adult mice and that basal neurogenesis in adult C3a/GFAP and C5a/GFAP mice is not altered. (c) 2007 Wiley-Liss, Inc.
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| 12. |
- Smith, Peter L P, 1982, et al.
(author)
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Neonatal Peripheral Immune Challenge Activates Microglia and Inhibits Neurogenesis in the Developing Murine Hippocampus.
- 2014
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In: Developmental neuroscience. - : S. Karger AG. - 1421-9859 .- 0378-5866. ; 36:2, s. 119-131
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Journal article (peer-reviewed)abstract
- The early postnatal period represents an important window in rodent hippocampal development with peak hilar neurogenesis and widespread microgliogenesis occurring in the first week of life. Inflammation occurring during this period may negatively influence development, potentially facilitating or increasing susceptibility to later-life pathology. We administered the Gram-negative bacterial coat protein lipopolysaccharide (LPS) systemically at postnatal day 5 (1 mg/kg i.p.) and assessed potential effects on microgliogenesis, inflammation and neurogenesis in the developing hippocampus. LPS administration led to an acute but transient increase in absolute number and density of ionized calcium-binding adaptor molecule 1-immunoreactive microglia, a change attributable to increased proliferation of central nervous system-resident microglia/microglial precursor cells but not infiltration of peripheral monocyte-derived macrophages. qRT-PCR analysis of hippocampal gene expression showed these LPS-mediated changes to be associated with persistent dysregulation of genes associated with both M1 and M2 microglial phenotypes, indicating prolonged alteration in hippocampal inflammatory status. Further, analysis of progenitor cell regulation in the hippocampal subgranular zone revealed a transient inhibition of the neuronal differentiation pathway up to 2 weeks after LPS administration, a change occurring specifically through effects on type 3 neural progenitor cells and independently of altered cell proliferation or survival of newly born cells. Together, our results show that systemic inflammation occurring during the early neonatal period is sufficient to alter inflammatory status and dysregulate the ongoing process of neurogenesis in the developing hippocampal germinal niche. © 2014 S. Karger AG, Basel.
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| 13. |
- Smith, Peter L P, 1982, et al.
(author)
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Peripheral myeloid cells contribute to brain injury in male neonatal mice
- 2018
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In: Journal of Neuroinflammation. - : Springer Science and Business Media LLC. - 1742-2094. ; 15:1
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Journal article (peer-reviewed)abstract
- BackgroundNeonatal brain injury is increasingly understood to be linked to inflammatory processes that involve specialised CNS and peripheral immune interactions. However, the role of peripheral myeloid cells in neonatal hypoxic-ischemic (HI) brain injury remains to be fully investigated.MethodsWe employed the Lys-EGFP-ki mouse that allows enhanced green fluorescent protein (EGFP)-positive mature myeloid cells of peripheral origin to be easily identified in the CNS. Using both flow cytometry and confocal microscopy, we investigated the accumulation of total EGFP(+) myeloid cells and myeloid cell subtypes: inflammatory monocytes, resident monocytes and granulocytes, in the CNS for several weeks following induction of cerebral HI in postnatal day 9 mice. We used antibody treatment to curb brain infiltration of myeloid cells and subsequently evaluated HI-induced brain injury.ResultsWe demonstrate a temporally biphasic pattern of inflammatory monocyte and granulocyte infiltration, characterised by peak infiltration at 1day and 7days after hypoxia-ischemia. This occurs against a backdrop of continuous low-level resident monocyte infiltration. Antibody-mediated depletion of circulating myeloid cells reduced immune cell accumulation in the brain and reduced neuronal loss in male but not female mice.ConclusionThis study offers new insight into sex-dependent central-peripheral immune communication following neonatal brain injury and merits renewed interest in the roles of granulocytes and monocytes in lesion development.
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| 14. |
- Stridh, Linnea, 1983, et al.
(author)
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Regulation of Toll-like receptor 1 and -2 in neonatal mouse brain after hypoxia-ischemia.
- 2011
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In: Journal of neuroinflammation. - : Springer Science and Business Media LLC. - 1742-2094. ; 8:1
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Journal article (peer-reviewed)abstract
- ABSTRACT: BACKGROUND: Hypoxic-ischemic (HI) brain injury remains a major problem in newborns, resulting in increased risk of neurological disorders. Neonatal HI triggers a broad inflammatory reaction in the brain, including activation of the innate immune system. Toll-like receptors (TLRs), which are key components of the innate immune system, are believed to play a role in adult cerebral ischemic injury. The expression of TLRs in the neonatal brain and their regulation after HI is unknown. METHODS: Wild type C57BL/6, TLR 1 knockout (KO) and TLR 2 KO mice were subjected to HI at postnatal day 9 and sacrificed 30 min, 6h, 24h or 5 days after HI. TLR mRNA expression was determined by RT-qPCR and protein and cell type localisation by immunohistochemistry (IHC). To evaluate brain injury, infarct volume was measured in the injured hemisphere. RESULTS: mRNA expression was detected for all investigated TLRs (TLR1-9), both in normal and HI exposed brains. After HI, TLR-1 was down-regulated at 30 min and up-regulated at 6h and 24h. TLR-2 was up-regulated at 6h and 24h, and TLR-7 at 24h. Both TLR-5 and TLR-8 were down-regulated at 24h and 30 min respectively. IHC showed an increase of TLR-1 in neurons in the ipsilateral hemisphere after HI. TLR-2 was constitutively expressed in astrocytes and in a population of neurons in the paraventricular nucleus in the hypothalamus. No changes in expression were detected following HI. Following HI, TLR-2 KO mice, but not TLR-1 KO, showed a decreased infarct volume compared to wild type (p= 0.0051). CONCLUSIONS: This study demonstrates that TLRs are regulated after HI in the neonatal brain. TLR-1 protein was up-regulated in injured areas of the brain but TLR-1 KO animals were not protected from HI. In contrast, TLR-2 was constitutively expressed in the brain and TLR-2 deficiency reduced HI injury. These data suggest that TLR-2, but not TLR-1, plays a role in neonatal HI brain injury.
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| 15. |
- Wilhelmsson, Ulrika, 1970, et al.
(author)
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Astrocytes negatively regulate neurogenesis through the Jagged1-mediated notch pathway.
- 2012
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In: Stem cells (Dayton, Ohio). - : Oxford University Press (OUP). - 1549-4918 .- 1066-5099. ; 30:10, s. 2320-9
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Journal article (peer-reviewed)abstract
- Adult neurogenesis is regulated by a number of cellular players within the neurogenic niche. Astrocytes participate actively in brain development, regulation of the mature central nervous system (CNS), and brain plasticity. They are important regulators of the local environment in adult neurogenic niches through the secretion of diffusible morphogenic factors, such as Wnts. Astrocytes control the neurogenic niche also through membrane-associated factors, however, the identity of these factors and the mechanisms involved are largely unknown. In this study, we sought to determine the mechanisms underlying our earlier finding of increased neuronal differentiation of neural progenitor cells when cocultured with astrocytes lacking glial fibrillary acidic protein (GFAP) and vimentin (GFAP(-/-) Vim(-/-) ). We used primary astrocyte and neurosphere cocultures to demonstrate that astrocytes inhibit neuronal differentiation through a cell-cell contact. GFAP(-/-) Vim(-/-) astrocytes showed reduced endocytosis of Notch ligand Jagged1, reduced Notch signaling, and increased neuronal differentiation of neurosphere cultures. This effect of GFAP(-/-) Vim(-/-) astrocytes was abrogated in the presence of immobilized Jagged1 in a manner dependent on the activity of γ-secretase. Finally, we used GFAP(-/-) Vim(-/-) mice to show that in the absence of GFAP and vimentin, hippocampal neurogenesis under basal conditions as well as after injury is increased. We conclude that astrocytes negatively regulate neurogenesis through the Notch pathway, and endocytosis of Notch ligand Jagged1 in astrocytes and Notch signaling from astrocytes to neural stem/progenitor cells depends on the intermediate filament proteins GFAP and vimentin.
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