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Interferon regulatory factor 3 plays an anti-inflammatory role in microglia by activating the PI3K/Akt pathway

BACKGROUND: Microglia are the principal cells involved in the innate immune response in the CNS. Activated microglia produce a number of proinflammatory cytokines implicated in neurotoxicity but they also are a major source of anti-inflammatory cytokines, antiviral proteins and growth factors. There...

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Autores principales: Tarassishin, Leonid, Suh, Hyeon-Sook, Lee, Sunhee C
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2011
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3259120/
https://www.ncbi.nlm.nih.gov/pubmed/22208359
http://dx.doi.org/10.1186/1742-2094-8-187
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author Tarassishin, Leonid
Suh, Hyeon-Sook
Lee, Sunhee C
author_facet Tarassishin, Leonid
Suh, Hyeon-Sook
Lee, Sunhee C
author_sort Tarassishin, Leonid
collection PubMed
description BACKGROUND: Microglia are the principal cells involved in the innate immune response in the CNS. Activated microglia produce a number of proinflammatory cytokines implicated in neurotoxicity but they also are a major source of anti-inflammatory cytokines, antiviral proteins and growth factors. Therefore, an immune therapy aiming at suppressing the proinflammatory phenotype while enhancing the anti-inflammatory, growth promoting phenotype would be of great benefit. In the current study, we tested the hypothesis that interferon regulatory factor 3 (IRF3), a transcription factor required for the induction of IFNβ following TLR3 or TLR4 activation, is critical to the microglial phenotype change from proinflammatory to anti-inflammatory, and that this phenotype change can be greatly facilitated by IRF3 gene transfer. METHODS: Cultures of primary human fetal microglia were transduced with IRF3 using recombinant adenovirus (Ad-IRF3) and subjected to microarray analysis, real-time PCR, immunoblotting and ELISA to determine inflammatory gene expression. Two different types of immune stimuli were tested, the TLR ligands, poly IC (PIC) and LPS, and the proinflammatory cytokines, IL-1/IFNγ. In addition, the role of the PI3K/Akt pathway was examined by use of a pharmacological inhibitor, LY294002. RESULTS: Our results show that Ad-IRF3 suppressed proinflammatory genes (IL-1α, IL-1β, TNFα, IL-6, IL-8 and CXCL1) and enhanced anti-inflammatory genes (IL-1 receptor antagonist, IL-10 and IFNβ) in microglia, regardless of the cell stimuli applied. Furthermore, Ad-IRF3 activated Akt, and LY294002 reversed the effects of Ad-IRF3 on microglial inflammatory gene expression. pAkt was critical in LPS- or PIC-induced production of IL-10 and IL-1ra. Significantly, microglial IFNβ protein production was also dependent on pAkt and required both Ad-IRF3 and immunological stimuli (PIC > IL-1/IFNγ). pAkt played much less prominent and variable roles in microglial proinflammatory gene expression. This anti-inflammatory promoting role of PI3K/Akt appeared to be specific to microglia, since astrocyte proinflammatory gene expression (as well as IFNβ expression) required PI3K/Akt. CONCLUSIONS: Our results show a novel anti-inflammatory role for the PI3K/Akt signaling pathway in microglia. They further suggest that IRF3 gene therapy could facilitate the microglial phenotype switch from proinflammatory ("M1-like") to anti-inflammatory and immunomodulatory ("M2-like"), in part, by augmenting the level of pAkt.
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spelling pubmed-32591202012-01-17 Interferon regulatory factor 3 plays an anti-inflammatory role in microglia by activating the PI3K/Akt pathway Tarassishin, Leonid Suh, Hyeon-Sook Lee, Sunhee C J Neuroinflammation Research BACKGROUND: Microglia are the principal cells involved in the innate immune response in the CNS. Activated microglia produce a number of proinflammatory cytokines implicated in neurotoxicity but they also are a major source of anti-inflammatory cytokines, antiviral proteins and growth factors. Therefore, an immune therapy aiming at suppressing the proinflammatory phenotype while enhancing the anti-inflammatory, growth promoting phenotype would be of great benefit. In the current study, we tested the hypothesis that interferon regulatory factor 3 (IRF3), a transcription factor required for the induction of IFNβ following TLR3 or TLR4 activation, is critical to the microglial phenotype change from proinflammatory to anti-inflammatory, and that this phenotype change can be greatly facilitated by IRF3 gene transfer. METHODS: Cultures of primary human fetal microglia were transduced with IRF3 using recombinant adenovirus (Ad-IRF3) and subjected to microarray analysis, real-time PCR, immunoblotting and ELISA to determine inflammatory gene expression. Two different types of immune stimuli were tested, the TLR ligands, poly IC (PIC) and LPS, and the proinflammatory cytokines, IL-1/IFNγ. In addition, the role of the PI3K/Akt pathway was examined by use of a pharmacological inhibitor, LY294002. RESULTS: Our results show that Ad-IRF3 suppressed proinflammatory genes (IL-1α, IL-1β, TNFα, IL-6, IL-8 and CXCL1) and enhanced anti-inflammatory genes (IL-1 receptor antagonist, IL-10 and IFNβ) in microglia, regardless of the cell stimuli applied. Furthermore, Ad-IRF3 activated Akt, and LY294002 reversed the effects of Ad-IRF3 on microglial inflammatory gene expression. pAkt was critical in LPS- or PIC-induced production of IL-10 and IL-1ra. Significantly, microglial IFNβ protein production was also dependent on pAkt and required both Ad-IRF3 and immunological stimuli (PIC > IL-1/IFNγ). pAkt played much less prominent and variable roles in microglial proinflammatory gene expression. This anti-inflammatory promoting role of PI3K/Akt appeared to be specific to microglia, since astrocyte proinflammatory gene expression (as well as IFNβ expression) required PI3K/Akt. CONCLUSIONS: Our results show a novel anti-inflammatory role for the PI3K/Akt signaling pathway in microglia. They further suggest that IRF3 gene therapy could facilitate the microglial phenotype switch from proinflammatory ("M1-like") to anti-inflammatory and immunomodulatory ("M2-like"), in part, by augmenting the level of pAkt. BioMed Central 2011-12-30 /pmc/articles/PMC3259120/ /pubmed/22208359 http://dx.doi.org/10.1186/1742-2094-8-187 Text en Copyright ©2011 Tarassishin et al; licensee BioMed Central Ltd. http://creativecommons.org/licenses/by/2.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
spellingShingle Research
Tarassishin, Leonid
Suh, Hyeon-Sook
Lee, Sunhee C
Interferon regulatory factor 3 plays an anti-inflammatory role in microglia by activating the PI3K/Akt pathway
title Interferon regulatory factor 3 plays an anti-inflammatory role in microglia by activating the PI3K/Akt pathway
title_full Interferon regulatory factor 3 plays an anti-inflammatory role in microglia by activating the PI3K/Akt pathway
title_fullStr Interferon regulatory factor 3 plays an anti-inflammatory role in microglia by activating the PI3K/Akt pathway
title_full_unstemmed Interferon regulatory factor 3 plays an anti-inflammatory role in microglia by activating the PI3K/Akt pathway
title_short Interferon regulatory factor 3 plays an anti-inflammatory role in microglia by activating the PI3K/Akt pathway
title_sort interferon regulatory factor 3 plays an anti-inflammatory role in microglia by activating the pi3k/akt pathway
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3259120/
https://www.ncbi.nlm.nih.gov/pubmed/22208359
http://dx.doi.org/10.1186/1742-2094-8-187
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