Notch Activation Enhances the Microglia-Mediated Inflammatory Response Associated With Focal Cerebral Ischemia

    Authors

    Z. L. Wei; S. Chigurupati; T. V. Arumugam; D. G. Jo; H. Li;S. L. Chan

    Comments

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    Abbreviated Journal Title

    Stroke

    Keywords

    apoptosis; brain ischemia; focal ischemia; inflammation; neuroprotection; neuroregeneration; NF-KAPPA-B; TUMOR-NECROSIS-FACTOR; UP-REGULATION; BRAIN-DAMAGE; STROKE; CELLS; PROLIFERATION; DEATH; Clinical Neurology; Peripheral Vascular Disease

    Abstract

    Background and Purpose-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 gamma-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-kappa B 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-kappa B 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. (Stroke. 2011;42:2589-2594.)

    Journal Title

    Stroke

    Volume

    42

    Issue/Number

    9

    Publication Date

    1-1-2011

    Document Type

    Article

    Language

    English

    First Page

    2589

    Last Page

    U344

    WOS Identifier

    WOS:000294342800048

    ISSN

    0039-2499

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