Non-invasively triggered spreading depolarizations induce a rapid pro-inflammatory response in cerebral cortex

Tsubasa Takizawa, Tao Qin, Andreia Lopes de Morais, Kazutaka Sugimoto, Joon Yong Chung, Liza Morsett, Inge Mulder, Paul Fischer, Tomoaki Suzuki, Maryam Anzabi, Maximilian Böhm, Wen-Sheng Qu, Takeshi Yanagisawa, Suzanne Hickman, Joseph El Khoury, Michael J. Whalen, Andrea M. Harriott, David Y. Chung, Cenk Ayata

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Cortical spreading depolarization (CSD) induces pro-inflammatory gene expression in brain tissue. However, previous studies assessing the relationship between CSD and inflammation have used invasive methods that directly trigger inflammation. To eliminate the injury confounder, we induced CSDs non-invasively through intact skull using optogenetics in Thy1-channelrhodopsin-2 transgenic mice. We corroborated our findings by minimally invasive KCl-induced CSDs through thinned skull. Six CSDs induced over 1 h dramatically increased cortical interleukin-1β (IL-1β), chemokine (C-C motif) ligand 2 (CCL2), and tumor necrosis factor-α (TNF-α) mRNA expression peaking around 1, 2 and 4 h, respectively. Interleukin-6 (IL-6) and intercellular adhesion molecule-1 (ICAM-1) were only modestly elevated. A single CSD also increased IL-1β, CCL2, and TNF-α, and revealed an ultra-early IL-1β response within 10 min. The response was blunted in IL-1 receptor-1 knockout mice, implicating IL-1β as an upstream mediator, and suppressed by dexamethasone, but not ibuprofen. CSD did not alter systemic inflammatory indices. In summary, this is the first report of pro-inflammatory gene expression after non-invasively induced CSDs. Altogether, our data provide novel insights into the role of CSD-induced neuroinflammation in migraine headache pathogenesis and have implications for the inflammatory processes in acute brain injury where numerous CSDs occur for days.
Original languageEnglish
JournalJournal of cerebral blood flow and metabolism
Publication statusPublished - 1 Jan 2019
Externally publishedYes

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