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Brain dendritic cells in ischemic stroke: time course, activation state, and origin.

ABSTRACT: The immune response to stroke is comprised of inflammatory and regulatory processes. One cell type involved in both innate and adaptive immunity is the dendritic cell (DC). A DC population residing in the healthy brain (bDC) was identified using a transgenic mouse expressing enhanced yellow fluorescent protein (EYFP) under the promoter for the DC marker, CD11c (CD11c/EYFP Tg). To determine if bDC are involved in the immune response to cerebral ischemia, transient (40 min) middle cerebral artery occlusion (MCAO) followed by 6, 24, or 72 h reperfusion was conducted in CD11c/EYFP Tg mice. Our results demonstrated that DC accumulated in the ischemic hemisphere at 24 h post-MCAO-reperfusion, particularly in the border region of the infarct where T lymphocytes accrued. To distinguish resident bDC from the infiltrating peripheral DC, radiation chimeras [1. wild type (WT) hosts restored with CD11c/EYFP Tg bone marrow (BM) or 2. CD11c/EYFP Tg hosts restored with WT BM] were generated and examined by immunocytochemistry. These data confirmed that DC populating the core of the infarct at 72 h were of peripheral origin, whereas those in the border region were comprised primarily of resident bDC. The brain resident (CD45 intermediate) cells of CD11c/EYFP Tg mice were analyzed by flow cytometry. Compared to microglia, bDC displayed increased major histocompatibility class II (MHC II) and co-stimulatory molecules following MCAO-reperfusion. High levels of MHC II and the co-stimulatory molecule CD80 on bDC at 72 h corresponded to peak lymphocyte infiltration, and suggested a functional interaction between these two immune cell populations.

SUBMITTER: Felger JC

PROVIDER: S-EPMC2885548 | biostudies-literature | 2010 Jul

REPOSITORIES: biostudies-literature

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Brain dendritic cells in ischemic stroke: time course, activation state, and origin.

Felger Jennifer C JC Abe Takato T Kaunzner Ulrike W UW Gottfried-Blackmore Andres A Gal-Toth Judit J McEwen Bruce S BS Iadecola Costantino C Bulloch Karen K

Brain, behavior, and immunity 20091113 5

The immune response to stroke is comprised of inflammatory and regulatory processes. One cell type involved in both innate and adaptive immunity is the dendritic cell (DC). A DC population residing in the healthy brain (bDC) was identified using a transgenic mouse expressing enhanced yellow fluorescent protein (EYFP) under the promoter for the DC marker, CD11c (CD11c/EYFP Tg). To determine if bDC are involved in the immune response to cerebral ischemia, transient (40 min) middle cerebral artery ...[more]

PMID: 19914372

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Project description:Background and objectivesThe goal of this work was to investigate the short-term time-course benefit and risk of ticagrelor with aspirin in acute mild-moderate ischemic stroke or high-risk TIA in The Acute Stroke or Transient Ischemic Attack Treated with Ticagrelor and ASA for Prevention of Stroke and Death (THALES) trial.MethodsIn an exploratory analysis of the THALES trial, we evaluated the cumulative incidence of irreversible efficacy and safety outcomes at different time points during the 30-day treatment period. The efficacy outcome was major ischemic events defined as a composite of ischemic stroke or nonhemorrhagic death. The safety outcome was major hemorrhage defined as a composite of intracranial hemorrhage and fatal bleedings. Net clinical impact was defined as the combination of these 2 endpoints.ResultsThis analysis included a total of 11,016 patients (5,523 in the ticagrelor-aspirin group, 5,493 in the aspirin group) with a mean age of 65 years, and 39% were women. The reduction of major ischemic events by ticagrelor occurred in the first week (4.1% vs 5.3%; absolute risk reduction 1.15%, 95% CI 0.36%-1.94%) and remained throughout the 30-day treatment period. An increase in major hemorrhage was seen during the first week and remained relatively constant in the following weeks (absolute risk increase ≈0.3%). Cumulative analysis showed that the net clinical impact favored ticagrelor-aspirin in the first week (absolute risk reduction 0.97%, 95% CI, 0.17%-1.77%) and remained constant throughout the 30 days.DiscussionIn patients with mild-moderate ischemic stroke or high-risk TIA, the treatment effect of ticagrelor-aspirin was present from the first week. The ischemic benefit of ticagrelor-aspirin outweighs the risk of major hemorrhage throughout the treatment period, which may support the use of 30-day treatment with ticagrelor and aspirin in these patients.Classification of evidenceThis study provides Class II evidence that, for patients with mild-moderate ischemic stroke or high-risk TIA, the ischemic benefit of ticagrelor-aspirin outweighs the risk of major hemorrhage throughout the 30-day treatment period.

Project description:BackgroundThe innate lymphoid cell (ILC) family consists of NK cells, ILC type 1, 2, 3 and lymphoid tissue inducer cells. They have been shown to play important roles in homeostasis and immune responses and are generally considered tissue resident. Not much is known about the presence of ILC members within the central nervous system and whether they are tissue resident in this organ too. Therefore, we studied the presence of all ILC members within the central nervous system and after ischemic brain insult.MethodsWe used the photothrombotic ischemic lesion method to induce ischemic lesions within the mouse brain. Using whole-mount immunofluorescence imaging, we established that the ILCs were present at the rim of the lesion. We quantified the increase of all ILC members at different time-points after the ischemic lesion induction by flow cytometry. Their migration route via chemokine CXCL12 was studied by using different genetic mouse models, in which we induced deletion of Cxcl12 within the blood-brain barrier endothelium, or its receptor, Cxcr4, in the ILCs. The functional role of the ILCs was subsequently established using the beam-walk sensorimotor test.ResultsHere, we report that ILCs are not resident within the mouse brain parenchyma during steady-state conditions, but are attracted towards the ischemic stroke. Specifically, we identify NK cells, ILC1s, ILC2s and ILC3s within the lesion, the highest influx being observed for NK cells and ILC1s. We further show that CXCL12 expressed at the blood-brain barrier is essential for NK cells and NKp46+ ILC3s to migrate toward the lesion. Complementary, Cxcr4-deficiency in NK cells prevents NK cells from entering the infarct area. Lack of NK cell migration results in a higher neurological deficit in the beam-walk sensorimotor test.ConclusionsThis study establishes the lack of ILCs in the mouse central nervous system at steady-state and their migration towards an ischemic brain lesion. Our data show a role for blood-brain barrier-derived CXCL12 in attracting protective NK cells to ischemic brain lesions and identifies a new CXCL12/CXCR4-mediated component of the innate immune response to stroke.

Dataset Information

Brain dendritic cells in ischemic stroke: time course, activation state, and origin.

Publications

Brain dendritic cells in ischemic stroke: time course, activation state, and origin.

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