title: MicroRNA-146a: a key regulator of astrocyte-mediated inflammatory response.
abstract: Increasing evidence supports the involvement of microRNAs (miRNA) in the regulation of inflammation in human neurological disorders. In the present study we investigated the role of miR-146a, a key regulator of the innate immune response, in the modulation of astrocyte-mediated inflammation. Using Taqman PCR and in situ hybridization, we studied the expression of miR-146a in epilepsy-associated glioneuronal lesions which are characterized by prominent activation of the innate immune response. In addition, cultured human astrocytes were used to study the regulation of miR-146a expression in response to proinflammatory cytokines. qPCR and western blot were used to evaluate the effects of overexpression or knockdown of miR-146a on IL-1β signaling. Downstream signaling in the IL-1β pathway, as well as the expression of IL-6 and COX-2 were evaluated by western blot and ELISA. Release several cytokines was evaluated using a human magnetic multiplex cytokine assay on a Luminex® 100™/200™ platform. Increased expression of miR-146a was observed in glioneuronal lesions by Taqman PCR. MiR-146a expression in human glial cell cultures was strongly induced by IL-1β and blocked by IL-1β receptor antagonist. Modulation of miR-146a expression by transfection of astrocytes with anti-miR146a or mimic, regulated the mRNA expression levels of downstream targets of miR-146a (IRAK-1, IRAK-2 and TRAF-6) and the expression of IRAK-1 protein. In addition, the expression of IL-6 and COX-2 upon IL-1β stimulation was suppressed by increased levels of miR-146a and increased by the reduction of miR-146a. Modulation of miR-146a expression affected also the release of several cytokines such as IL-6 and TNF-α. Our observations indicate that in response to inflammatory cues, miR-146a was induced as a negative-feedback regulator of the astrocyte-mediated inflammatory response. This supports an important role of miR-146a in human neurological disorders associated with chronic inflammation and suggests that this miR may represent a novel target for therapeutic strategies.
authors.affiliation: Department of Neuro-Pathology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Anand
authors.initials: A
authors.lastname: Iyer
authors.forename: Emanuele
authors.initials: E
authors.lastname: Zurolo
authors.forename: Avanita
authors.initials: A
authors.lastname: Prabowo
authors.forename: Kees
authors.initials: K
authors.lastname: Fluiter
authors.forename: Wim G M
authors.initials: WG
authors.lastname: Spliet
authors.forename: Peter C
authors.initials: PC
authors.lastname: van Rijen
authors.forename: Jan A
authors.initials: JA
authors.lastname: Gorter
authors.forename: Eleonora
authors.initials: E
authors.lastname: Aronica
mesh_terms: D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D001927:Brain Diseases / Q000235:genetics / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D051546:Cyclooxygenase 2 / Q000378:metabolism; D004827:Epilepsy / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D005260:Female; D018303:Ganglioglioma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D007113:Immunity, Innate / Q000187:drug effects; D018836:Inflammation Mediators / Q000378:metabolism*; D053592:Interleukin-1 Receptor-Associated Kinases / Q000378:metabolism; D053583:Interleukin-1beta / Q000494:pharmacology; D015850:Interleukin-6 / Q000378:metabolism; D008297:Male; D054220:Malformations of Cortical Development / Q000235:genetics / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D065703:Malformations of Cortical Development, Group I; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D011247:Pregnancy; D017472:Receptors, Interleukin-1 / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D048029:TNF Receptor-Associated Factor 6 / Q000378:metabolism; D051193:Toll-Like Receptors / Q000378:metabolism
chemical_list: D018836:Inflammation Mediators; D053583:Interleukin-1beta; D015850:Interleukin-6; C542542:MIRN146 microRNA, human; D035683:MicroRNAs; D016328:NF-kappa B; D017472:Receptors, Interleukin-1; D048029:TNF Receptor-Associated Factor 6; D051193:Toll-Like Receptors; D051546:Cyclooxygenase 2; D053592:Interleukin-1 Receptor-Associated Kinases