[PDF][PDF] Autocrine loop involving IL-6 family member LIF, LIF receptor, and STAT4 drives sustained fibroblast production of inflammatory mediators

HN Nguyen, EH Noss, F Mizoguchi, C Huppertz… - Immunity, 2017 - cell.com
HN Nguyen, EH Noss, F Mizoguchi, C Huppertz, KS Wei, GFM Watts, MB Brenner
Immunity, 2017cell.com
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 after fibroblast …
Summary
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 after 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.
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