Activated microglia in ischemic stroke penumbra upregulate MCP‐1 and CCR2 expression in response to lysophosphatidylcholine derived from adjacent neurons and astrocytes

作者：Yuri, Inose; Yoichiro, Kato; Kazuo, Kitagawa; Shinichiro, Uchiyama; Noriyuki, Shibata

来源：Neuropathology, 2015, 35(3): 209-223.

DOI：10.1111/neup.12182

<jats:p>In acute stage of ischemic stroke, the surrounding zone of fresh infarcts is termed penumbra, where microglia are activated in response to damaged cell‐derived proinflammatory mediators. Rescuing penumbra by regulating inflammatory activity would minimize infarct volume, which positively correlates with functional outcome. To elucidate mechanisms by which inflammation occurs in penumbra, we performed immunohistochemical investigations using autopsied human brains affected by acute, subacute and chronic stages of cerebral infarction as well as cell culture experiments using a murine microglia‐derived cell line (<jats:styled-content style="fixed-case">BV</jats:styled-content>‐2). In penumbra of fresh infarcts, immunoreactivity for secretory phospholipase <jats:styled-content style="fixed-case">A<jats:sub>2</jats:sub></jats:styled-content> group <jats:styled-content style="fixed-case">X</jats:styled-content> (<jats:styled-content style="fixed-case">sPLA<jats:sub>2</jats:sub>‐X</jats:styled-content>), which is responsible for the production and release of the proinflammatory mediator lysophosphatidylcholine (<jats:styled-content style="fixed-case">LPC</jats:styled-content>), was intensely detected in neurons and astrocytes. Furthermore, immunoreactivities for the <jats:styled-content style="fixed-case">LPC</jats:styled-content> receptors <jats:styled-content style="fixed-case">G</jats:styled-content> protein‐coupled receptor 132 (<jats:styled-content style="fixed-case">G2A</jats:styled-content>) and <jats:styled-content style="fixed-case">P2X</jats:styled-content> purinoreceptor 7 (<jats:styled-content style="fixed-case">P2X7R</jats:styled-content>), as well as the <jats:styled-content style="fixed-case">CC</jats:styled-content> chemokine monocyte chemoattractant protein‐1 (<jats:styled-content style="fixed-case">MCP</jats:styled-content>‐1) and its receptor <jats:styled-content style="fixed-case">CCR2</jats:styled-content>, were detectable in activated microglia. Prior to cell culture experiments, it was confirmed that <jats:styled-content style="fixed-case">BV</jats:styled-content>‐2 cells were immunoreactive for ionized <jats:styled-content style="fixed-case"><jats:roman>Ca<jats:sup>2+</jats:sup></jats:roman></jats:styled-content>‐binding adaptor molecule 1 (Iba1), <jats:styled-content style="fixed-case">G2A</jats:styled-content>, <jats:styled-content style="fixed-case">P2X7R</jats:styled-content>, <jats:styled-content style="fixed-case">MCP</jats:styled-content>‐1 and <jats:styled-content style="fixed-case">CCR2</jats:styled-content>. Reverse transcription‐quantitative polymerase chain reaction analysis revealed that <jats:styled-content style="fixed-case">MCP</jats:styled-content>‐1 and <jats:styled-content style="fixed-case">CCR2 mRNA</jats:styled-content> expression levels were significantly increased by <jats:styled-content style="fixed-case">LPC</jats:styled-content> stimulation. The <jats:styled-content style="fixed-case">LPC</jats:styled-content>‐driven increase in <jats:styled-content style="fixed-case">MCP</jats:styled-content>‐1 transcripts was lowered by blockade of <jats:styled-content style="fixed-case">G2A</jats:styled-content> or <jats:styled-content style="fixed-case">P2X7R</jats:styled-content> or by inhibition of Rho‐associated protein kinase (<jats:styled-content style="fixed-case">ROCK</jats:styled-content>) or inhibitor of <jats:styled-content style="fixed-case">κBα</jats:styled-content> kinase. The <jats:styled-content style="fixed-case">LPC</jats:styled-content>‐driven increase in <jats:styled-content style="fixed-case">CCR2</jats:styled-content> transcripts was lowered by blockade of <jats:styled-content style="fixed-case">G2A</jats:styled-content> or <jats:styled-content style="fixed-case">P2X7R</jats:styled-content> or by inhibition of <jats:styled-content style="fixed-case">ROCK</jats:styled-content>, phosphatidylinositide 3‐kinanse, extracellular signal‐regulated kinase kinase, or p38 mitogen‐activated protein kinase. The present results provide <jats:italic>in vivo</jats:italic> and <jats:italic>in vitro</jats:italic> evidence that in acute stage of ischemic stroke, the <jats:styled-content style="fixed-case">sPLA<jats:sub>2</jats:sub>‐X</jats:styled-content> enzyme product <jats:styled-content style="fixed-case">LPC</jats:styled-content> is released from neurons and astrocytes and stimulates penumbra microglia via <jats:styled-content style="fixed-case">G2A</jats:styled-content> and <jats:styled-content style="fixed-case">P2X7R</jats:styled-content>, thereby exerting the <jats:styled-content style="fixed-case">MCP‐1/CCR2</jats:styled-content>‐mediated neurotoxicity through distinct cell‐signaling pathways.</jats:p>

• 出版日期2015-6
• 单位南方医科大学