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  • Autocrine feedback loop inv...
    Nguyen, Hung N.; Noss, Erika H.; Mizoguchi, Fumitaka; Huppertz, Christine; Wei, Kevin S.; Watts, Gerald F. M.; Brenner, Michael B.

    Immunity (Cambridge, Mass.), 02/2017, Letnik: 46, Številka: 2
    Journal Article

    Fibroblasts are major contributors to and regulators of inflammation and dominant producers of interleukin-6 (IL-6) in inflammatory diseases like rheumatoid arthritis. Yet, compared to leukocytes, the regulation of inflammatory pathways in fibroblasts is largely unknown. Here, we report that analyses of genes coordinately upregulated with IL-6 pointed to STAT4 and leukemia inhibitory factor (LIF) as potentially linked. Gene silencing revealed that STAT4 was required for IL-6 transcription. STAT4 was recruited to the IL-6 promoter following fibroblast activation, and LIF receptor (LIFR) and STAT4 formed a molecular complex that together with JAK1 and TYK2 kinases, controlled STAT4 activation. Importantly, a positive feedback loop involving autocrine LIF, LIFR and STAT4 drove sustained IL-6 transcription. Besides IL-6, this autorine loop also drove the production of other key inflammatory factors including IL-8, granulocyte-colony stimulating factor (G-CSF), IL-33, IL-11, IL-1α and IL-1β. These findings define the transcriptional regulation of fibroblast-mediated inflammation as distinct from leukocytes. Growing evidence implicates fibroblasts as inflammatory cells in sites of peripheral inflammation. Nguyen and colleagues demonstrate that regulation of IL-6 along with a set of other inflammatory cytokines and chemokines is regulated by a positive feedback loop involving LIF, LIF receptor, and STAT4 that selectively operates in fibroblasts.