Translocator protein (18?kDa) (TSPO) is expressed in reactive retinal microglia and modulates microglial inflammation and phagocytosis

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• 作者：Marcus Karlstetter (1)
  Caroline Nothdurfter (2)
  Alexander Aslanidis (1)
  Katharina Moeller (1)
  Felicitas Horn (1)
  Rebecca Scholz (1)
  Harald Neumann (3)
  Bernhard H F Weber (4)
  Rainer Rupprecht (2)
  Thomas Langmann (1)
  
• 关键词：Translocator protein (18?kDa) ; Microglia ; Retinal degeneration ; Phagocytosis
• 刊名：Journal of Neuroinflammation
• 出版年：2014
• 出版时间：December 2014
• 年：2014
• 卷：11
• 期：1
• 全文大小：1,020 KB
• 作者单位：Marcus Karlstetter (1)
  Caroline Nothdurfter (2)
  Alexander Aslanidis (1)
  Katharina Moeller (1)
  Felicitas Horn (1)
  Rebecca Scholz (1)
  Harald Neumann (3)
  Bernhard H F Weber (4)
  Rainer Rupprecht (2)
  Thomas Langmann (1)
  
  1. Department of Ophthalmology, University of Cologne, D-50931, Cologne, Germany
  2. Department of Psychiatry and Psychotherapy, University of Regensburg, D-93053, Regensburg, Germany
  3. Institute of Reconstructive Neurobiology, University of Bonn, D-53127, Bonn, Germany
  4. Institute of Human Genetics, University of Regensburg, D-93053, Regensburg, Germany
  
• ISSN：1742-2094

文摘

Background The translocator protein (18?kDa) (TSPO) is a mitochondrial protein expressed on reactive glial cells and a biomarker for gliosis in the brain. TSPO ligands have been shown to reduce neuroinflammation in several mouse models of neurodegeneration. Here, we analyzed TSPO expression in mouse and human retinal microglia and studied the effects of the TSPO ligand XBD173 on microglial functions. Methods TSPO protein analyses were performed in retinoschisin-deficient mouse retinas and human retinas. Lipopolysaccharide (LPS)-challenged BV-2 microglial cells were treated with XBD173 and TSPO shRNAs in vitro and pro-inflammatory markers were determined by qRT-PCR. The migration potential of microglia was determined with wound healing assays and the proliferation was studied with Fluorescence Activated Cell Sorting (FACS) analysis. Microglial neurotoxicity was estimated by nitrite measurement and quantification of caspase 3/7 levels in 661?W photoreceptors cultured in the presence of microglia-conditioned medium. The effects of XBD173 on filopodia formation and phagocytosis were analyzed in BV-2 cells and human induced pluripotent stem (iPS) cell-derived microglia (iPSdM). The morphology of microglia was quantified in mouse retinal explants treated with XBD173. Results TSPO was strongly up-regulated in microglial cells of the dystrophic mouse retina and also co-localized with microglia in human retinas. Constitutive TSPO expression was high in the early postnatal Day 3 mouse retina and declined to low levels in the adult tissue. TSPO mRNA and protein were also strongly induced in LPS-challenged BV-2 microglia while the TSPO ligand XBD173 efficiently suppressed transcription of the pro-inflammatory marker genes chemokine (C-C motif) ligand 2 (CCL2), interleukin 6 (IL6) and inducible nitric oxide (NO)-synthase (iNOS). Moreover, treatment with XBD173 significantly reduced the migratory capacity and proliferation of microglia, their level of NO secretion and their neurotoxic activity on 661?W photoreceptor cells. Furthermore, XBD173 treatment of murine and human microglial cells promoted the formation of filopodia and increased their phagocytic capacity to ingest latex beads or photoreceptor debris. Finally, treatment with XBD173 reversed the amoeboid alerted phenotype of microglial cells in explanted organotypic mouse retinal cultures after challenge with LPS. Conclusions These findings suggest that TSPO is highly expressed in reactive retinal microglia and a promising target to control microglial reactivity during retinal degeneration.