Article

Interferon Regulatory Factor 3 Inhibits Astrocyte Inflammatory Gene Expression Through Suppression of the Proinflammatory miR-155 and miR-155

Department of Pathology, Albert Einstein College of Medicine, Bronx, NY, USA.
Glia (Impact Factor: 6.03). 12/2011; 59(12):1911-22. DOI: 10.1002/glia.21233
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ABSTRACT Astrocytes, together with microglia and macrophages, participate in innate inflammatory responses in the CNS. Although inflammatory mediators such as interferons generated by astrocytes may be critical in the defense of the CNS, sustained unopposed cytokine signaling could result in harmful consequences. Interferon regulatory factor 3 (IRF3) is a transcription factor required for IFNβ production and antiviral immunity. Most cells express low levels of IRF3 protein, and the transcriptional mechanism that upregulates IRF3 expression is not known. In this study, we explored the consequence of adenovirus-mediated IRF3 gene transfer (Ad-IRF3) in primary human astrocytes. We show that IRF3 transgene expression suppresses proinflammatory cytokine gene expression upon challenge with IL-1/IFNγ and alters astrocyte activation phenotype from a proinflammatory to an anti-inflammatory one, akin to an M1-M2 switch in macrophages. This was accompanied by the rescue of neurons from cytokine-induced death in glial-neuronal co-cultures. Furthermore, Ad-IRF3 suppressed the expression of microRNA-155 and its star-form partner miR-155*, immunoregulatory miRNAs highly expressed in multiple sclerosis lesions. Astrocyte miR-155/miR155* were induced by cytokines and TLR ligands with a distinct hierarchy and involved in proinflammatory cytokine gene induction by targeting suppressor of cytokine signaling 1, a negative regulator of cytokine signaling and potentially other factors. Our results demonstrate a novel proinflammatory role for miR-155/miR-155* in human astrocytes and suggest that IRF3 can suppress neuroinflammation through regulating immunomodulatory miRNA expression. © 2011 Wiley-Liss, Inc.

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Available from: Sunhee C Lee, May 26, 2014
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    • "Previous studies have demonstrated that loss of critical components of the IFN signaling pathway, such as STAT1, can lead to enhanced inflammation and pathology during infection with HSV-1, and such disease can be independent of changes in viral titers (Lundberg et al., 2008; Pasieka et al., 2009, 2008). Several studies have also reported that IRF-3 has antiinflammatory properties which may help control immune-mediated pathology (Hua et al., 2002; Suh et al., 2009; Tarassishin et al., 2011a, 2011b). These studies therefore prompted us to investigate in this study whether a dysfunctional immune response was contributing to the observed pathology and mortality. "
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