title: Notch activation enhances the microglia-mediated inflammatory response associated with focal cerebral ischemia.
abstract: OBJECTIVE
  Activation of Notch worsens ischemic brain damage as antisense knockdown or pharmacological inhibition of the Notch pathway reduces the infarct size and improves the functional outcome in a mouse model of stroke. We sought to determine whether Notch activation contributes to postischemic inflammation by directly modulating the microglial innate response.
  
  
  METHODS
  The microglial response and the attendant inflammatory reaction were evaluated in Notch1 antisense transgenic (Tg) and in nontransgenic (non-Tg) mice subjected to middle cerebral artery occlusion with or without treatment with a γ-secretase inhibitor (GSI). To investigate the impact of Notch on microglial effector functions, primary mouse microglia and murine BV-2 microglial cell line were exposed to oxygen glucose deprivation or lipopolysaccharide in the presence or absence of GSI. Immunofluorescence labeling, Western blotting, and reverse-transcription polymerase chain reaction were performed to measure microglial activation and production of inflammatory cytokines. The nuclear translocation of nuclear factor-κB in microglia was assessed by immunohistochemistry. The neurotoxic potential of microglia was determined in cocultures.
  
  
  RESULTS
  Notch1 antisense mice exhibit significantly lower numbers of activated microglia and reduced proinflammatory cytokine expression in the ipsilateral ischemic cortices compared to non-Tg mice. Microglial activation also was attenuated in Notch1 antisense cultures and in non-Tg cultures treated with GSI. GSI significantly reduced nuclear factor-κB activation and expression of proinflammatory mediators and markedly attenuated the neurotoxic activity of microglia in cocultures.
  
  
  CONCLUSIONS
  These findings establish a role for Notch signaling in modulating the microglia innate response and suggest that inhibition of Notch might represent a complementary therapeutic approach to prevent reactive gliosis in stroke and neuroinflammation-related degenerative disorders.
authors: Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, 4000 Central Florida Blvd, Orlando, FL 32816, USA.
authors: Zelan
authors: Z
authors: Wei
authors: Srinivasulu
authors: S
authors: Chigurupati
authors: Thiruma V
authors: TV
authors: Arumugam
authors: Dong-Gyu
authors: DG
authors: Jo
authors: He
authors: H
authors: Li
authors: Sic L
authors: SL
authors: Chan
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000235:genetics / Q000276:immunology; D053829:Amyloid Precursor Protein Secretases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D000818:Animals; D002545:Brain Ischemia / Q000235:genetics / Q000276:immunology / Q000378:metabolism* / Q000473:pathology / Q000628:therapy; D002460:Cell Line; D002467:Cell Nucleus / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D018920:Coculture Techniques; D016207:Cytokines / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology; D005786:Gene Expression Regulation / Q000235:genetics / Q000276:immunology; D005911:Gliosis / Q000235:genetics / Q000276:immunology / Q000378:metabolism* / Q000473:pathology / Q000628:therapy; D007113:Immunity, Innate / Q000235:genetics / Q000276:immunology; D007249:Inflammation / Q000235:genetics / Q000276:immunology / Q000378:metabolism / Q000473:pathology / Q000628:therapy; D018836:Inflammation Mediators / Q000276:immunology / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D017628:Microglia / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D016328:NF-kappa B / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D009842:Oligopeptides / Q000494:pharmacology; D051881:Receptor, Notch1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000276:immunology / Q000378:metabolism*
chemical_list: D016207:Cytokines; D018836:Inflammation Mediators; D016328:NF-kappa B; C497762:Notch1 protein, mouse; D009842:Oligopeptides; D051881:Receptor, Notch1; C523462:benzyloxycarbonyl-leucyl-leucyl-norleucinal; D053829:Amyloid Precursor Protein Secretases