1
|
Takagi S, Furube E, Nakano Y, Morita M, Miyata S. Microglia are continuously activated in the circumventricular organs of mouse brain. J Neuroimmunol 2017; 331:74-86. [PMID: 29107327 DOI: 10.1016/j.jneuroim.2017.10.008] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2017] [Revised: 10/13/2017] [Accepted: 10/13/2017] [Indexed: 12/11/2022]
Abstract
Microglia are the primary resident immune cells of the brain parenchyma and transform into the amoeboid form in the "activated state" under pathological conditions from the ramified form in the "resting state" under physiologically healthy conditions. In the present study, we found that microglia in the circumventricular organs (CVOs) of adult mice displayed the amoeboid form with fewer branched cellular processes even under normal conditions; however, those in other brain regions showed the ramified form, which is characterized by well-branched and dendritic cellular processes. Moreover, microglia in the CVOs showed the strong protein expression of the M1 markers CD16/32 and CD86 and M2 markers CD206 and Ym1 without any pathological stimulation. Thus, the present results indicate that microglia in the CVOs of adult mice are morphologically and functionally activated under normal conditions, possibly due to the specialized features of the CVOs, namely, the entry of blood-derived molecules into parenchyma through fenestrated capillaries and the presence of neural stem cells.
Collapse
Affiliation(s)
- Shohei Takagi
- Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
| | - Eriko Furube
- Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
| | - Yousuke Nakano
- Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan; Department of Anatomy and Brain Science, Kansai Medical University, Hirakata, Japan
| | - Mitsuhiro Morita
- Department of Biology, Graduate School of Science, Kobe University, Kobe, Japan
| | - Seiji Miyata
- Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan.
| |
Collapse
|
2
|
Almolda B, de Labra C, Barrera I, Gruart A, Delgado-Garcia JM, Villacampa N, Vilella A, Hofer MJ, Hidalgo J, Campbell IL, González B, Castellano B. Alterations in microglial phenotype and hippocampal neuronal function in transgenic mice with astrocyte-targeted production of interleukin-10. Brain Behav Immun 2015; 45:80-97. [PMID: 25449577 DOI: 10.1016/j.bbi.2014.10.015] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Revised: 09/24/2014] [Accepted: 10/25/2014] [Indexed: 12/31/2022] Open
Abstract
Interleukin-10 (IL-10) is a cytokine classically linked with anti-inflammatory and protective functions in the central nervous system (CNS) in different neurodegenerative and neuroinflammatory conditions. In order to study the specific role of local CNS produced IL-10, we have created a new transgenic mouse line with astrocyte-targeted production of IL-10 (GFAP-IL10Tg). In the present study, the effects of local CNS IL-10 production on microglia, astrocytes and neuronal connectivity under basal conditions were investigated using immunohistochemistry, molecular biology techniques, electrophysiology and behavioural studies. Our results showed that, in GFAP-IL10Tg animals, microglia displayed an increase in density and a specific activated phenotype characterised by morphological changes in specific areas of the brain including the hippocampus, cortex and cerebellum that correlated with the level of transgene expressed IL-10 mRNA. Distinctively, in the hippocampus, microglial cells adopted an elongated morphology following the same direction as the dendrites of pyramidal neurons. Moreover, this IL-10-induced microglial phenotype showed increased expression of certain molecules including Iba1, CD11b, CD16/32 and F4/80 markers, "de novo" expression of CD150 and no detectable levels of either CD206 or MHCII. To evaluate whether this specific activated microglial phenotype was associated with changes in neuronal activity, the electrophysiological properties of pyramidal neurons of the hippocampus (CA3-CA1) were analysed in vivo. We found a lower excitability of the CA3-CA1 synapses and absence of long-term potentiation (LTP) in GFAP-IL10Tg mice. This study is the first description of a transgenic mouse with astrocyte-targeted production of the cytokine IL-10. The findings indicate that IL-10 induces a specific activated microglial phenotype concomitant with changes in hippocampal LTP responses. This transgenic animal will be a very useful tool to study IL-10 functions in the CNS, not only under basal conditions, but also after different experimental lesions or induced diseases.
Collapse
Affiliation(s)
- Beatriz Almolda
- Department of Cell Biology, Physiology and Immunology, Institute of Neuroscience, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain.
| | - Carmen de Labra
- Department of Cell Biology, Physiology and Immunology, Institute of Neuroscience, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain
| | - Iliana Barrera
- Department of Cell Biology, Physiology and Immunology, Institute of Neuroscience, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain
| | - Agnès Gruart
- Division of Neurosciences, Pablo de Olavide University, Seville 41013, Spain
| | | | - Nàdia Villacampa
- Department of Cell Biology, Physiology and Immunology, Institute of Neuroscience, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain
| | - Antonietta Vilella
- Department of Biomedical, Metabolic and Neural Sciences, Università degli Studi di Modena e Reggio Emilia, 41125, Italy
| | - Markus J Hofer
- School of Molecular Bioscience, The University of Sydney, Sydney, NSW 2006, Australia
| | - Juan Hidalgo
- Department of Cell Biology, Physiology and Immunology, Institute of Neuroscience, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain
| | - Iain L Campbell
- School of Molecular Bioscience, The University of Sydney, Sydney, NSW 2006, Australia
| | - Berta González
- Department of Cell Biology, Physiology and Immunology, Institute of Neuroscience, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain
| | - Bernardo Castellano
- Department of Cell Biology, Physiology and Immunology, Institute of Neuroscience, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain
| |
Collapse
|
3
|
Villacampa N, Almolda B, Vilella A, Campbell IL, González B, Castellano B. Astrocyte-targeted production of IL-10 induces changes in microglial reactivity and reduces motor neuron death after facial nerve axotomy. Glia 2015; 63:1166-84. [PMID: 25691003 DOI: 10.1002/glia.22807] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 01/28/2015] [Indexed: 12/30/2022]
Abstract
Interleukin-10 (IL-10) is a cytokine that plays a crucial role in regulating the inflammatory response and immune reactions. In the central nervous system (CNS), IL-10 is mainly produced by astrocytes and microglia and it is upregulated after various insults, such as experimental autoimmune encephalomyelitis, middle cerebral artery occlusion, excitotoxicity and traumatic brain injury. To better understand the effects of IL-10 in the normal and injured CNS, we generated transgenic mice (termed GFAP-IL-10Tg) that expressed the murine IL-10 gene under the transcriptional control of the glial fibrillary acidic protein (GFAP) promoter. Previous studies demonstrated marked changes in the microglial phenotype in these mice under basal conditions. The objective of the present study was to investigate the effects of local astrocyte-targeted IL-10 production on glial activation, neuronal degeneration and leukocyte recruitment after axotomy. GFAP-IL-10Tg mice had marked changes in the phenotype of activated microglial cells, as well as in the number of microglial clusters and in microglial cell density. These microglial changes are accompanied by a twofold increase in lymphocyte infiltration in GFAP-IL-10Tg mice and around twofold decrease in neuronal cell death at 21 dpi. Altogether, our findings suggested that astrocyte-targeted production of IL-10 impacted the microglial response and lymphocyte recruitment and culminated in a beneficial effect on neuronal survival.
Collapse
Affiliation(s)
- Nàdia Villacampa
- Department of Cell Biology, Physiology and Immunology, Institute of Neuroscience, Universitat Autònoma de Barcelona, Bellaterra, 08193, Barcelona, Spain
| | | | | | | | | | | |
Collapse
|