1. Role of TLR4 (Toll-Like Receptor 4) in N1/N2 Neutrophil Programming After Stroke
- Author
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Ignacio Lizasoain, Andrés Hidalgo, María A. Moro, Sara Palma-Tortosa, Ana Moraga, Violeta Durán-Laforet, María Isabel Cuartero, Angel L. Corbí, Juan de la Parra, Carolina Peña-Martínez, Alicia García-Culebras, Iván Ballesteros, Instituto de Salud Carlos III, Comunidad de Madrid, Ministerio de Economía y Competitividad (España), Ballesteros, Iván [0000-0002-6246-2353], Cuartero, María Isabel [0000-0003-4728-068X], de la Parra, Juan [0000-0002-4443-8931], Hidalgo, Andrés [0000-0001-5513-555X], Corbí, Angel L.[0000-0003-1980-5733], Moro, María A. [0000-0003-1010-8237], Lizasoain, Ignacio, Ballesteros, Iván, Cuartero, María Isabel, de la Parra, Juan, Hidalgo, Andrés, Corbí, Angel L., and Moro, María A.
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Male ,Pathology ,medicine.medical_specialty ,Neutrophils ,Population ,Ischemia ,Inflammation ,Neuroprotection ,Flow cytometry ,Mice ,03 medical and health sciences ,0302 clinical medicine ,Parenchyma ,medicine ,Animals ,Receptor ,education ,030304 developmental biology ,Mice, Knockout ,Advanced and Specialized Nursing ,0303 health sciences ,education.field_of_study ,medicine.diagnostic_test ,business.industry ,Brain ,Infarction, Middle Cerebral Artery ,medicine.disease ,Mice, Inbred C57BL ,Toll-Like Receptor 4 ,Phenotype ,Neutrophil Infiltration ,Infalmmation ,TLR4 ,Neurology (clinical) ,medicine.symptom ,Cardiology and Cardiovascular Medicine ,business ,030217 neurology & neurosurgery - Abstract
11p.-5 fig., Background and Purpose—After stroke, the population of infiltrated neutrophils in the brain is heterogeneous, including a population of alternative neutrophils (N2) that express M2 phenotype markers. We explored the role of TLR4 (toll-likereceptor 4) on neutrophil infiltration and polarization in this setting., Methods—Focal cerebral ischemia was induced by occlusion of the middle cerebral artery occlusion in TLR4-KO and WT (wild type) mice. Infarct size was measured by Nissl staining and magnetic resonance imaging. Leukocyte infiltration was quantified 48 hours after middle cerebral artery occlusion by immunofluorescence and flow cytometry. To elucidate mechanisms underlying TLR4-mediated N2 phenotype, a cDNA microarray analysis was performed in neutrophils isolated from blood 48 hours after stroke in WT and TLR4-KO mice., Results—As demonstrated previously, TLR4-deficient mice presented lesser infarct volumes than WT mice. TLR4-deficient mice showed higher density of infiltrated neutrophils 48 hours after stroke compared with WT mice, concomitantly to neuroprotection. Furthermore, cytometric and stereological analyses revealed an increased number of N2 neutrophils(YM1+ cells) into the ischemic core in TLR4-deficient mice, suggesting a protective effect of this neutrophil subset that was corroborated by depleting peripheral neutrophils or using mice with TLR4 genetically ablated in the myeloid lineage.Finally, cDNA microarray analysis in neutrophils, confirmed by quantitative polymerase chain reaction, showed that TLR4 modulates several pathways associated with ischemia-induced inflammation, migration of neutrophils into the parenchyma,and their functional priming, which might explain the opposite effect on outcome of the different neutrophil subsets., Conclusions—TLR4 deficiency increased the levels of alternative neutrophils (N2)—an effect associated with neuroprotection after stroke—supporting that modulation of neutrophil polarization is a major target of TLR4 and highlighting the crucial role of TLR4 at the peripheral level after stroke., This work was supported by grants from Instituto de Salud Carlos III and cofinanced by the European Development Regional Fund “A way to achieve Europe” (PI17/01601 and RETICS RD16/0019/0009;Dr Lizasoain), from Regional Madrid Government B2017/BMD-3688 (Dr Lizasoain) and from Spanish Ministry of Economy and Competitiveness SAF2015-68632-R (Dr Moro).
- Published
- 2019
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