IFNα enhances the production of IL-6 by human neutrophils activated via TLR8

Sci Rep. 2016 Jan 21:6:19674. doi: 10.1038/srep19674.

Abstract

Recently, we reported that human neutrophils produce biologically active amounts of IL-6 when incubated with agonists activating TLR8, a receptor recognizing viral single strand RNA. In this study, we demonstrate that IFNα, a cytokine that modulates the early innate immune responses toward viral and bacterial infections, potently enhances the production of IL-6 in neutrophils stimulated with R848, a TLR8 agonist. We also show that such an effect is not caused by an IFNα-dependent induction of TLR7 and its consequent co-activation with TLR8 in response to R848, but, rather, it is substantially mediated by an increased production and release of endogenous TNFα. The latter cytokine, in an autocrine manner, leads to an augmented synthesis of the IkBζ co-activator and an enhanced recruitment of the C/EBPβ transcription factor to the IL-6 promoter. Moreover, we show that neutrophils from SLE patients with active disease state, hence displaying an IFN-induced gene expression signature, produce increased amounts of both IL-6 and TNFα in response to R848 as compared to healthy donors. Altogether, data uncover novel effects that type I IFN exerts in TLR8-activated neutrophils, which therefore enlarge our knowledge on the various biological actions which type I IFN orchestrates during infectious and autoimmune diseases.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • CCAAT-Enhancer-Binding Protein-beta / metabolism
  • Cell Survival / drug effects
  • Female
  • Gene Expression Profiling
  • Gene Expression Regulation / drug effects
  • Genetic Loci
  • Humans
  • Imidazoles / pharmacology
  • Interferon-alpha / metabolism*
  • Interferon-alpha / pharmacology
  • Interleukin-6 / biosynthesis*
  • Interleukin-6 / genetics
  • Lupus Erythematosus, Systemic / genetics
  • Lupus Erythematosus, Systemic / immunology
  • Lupus Erythematosus, Systemic / metabolism
  • Middle Aged
  • Neutrophils / drug effects
  • Neutrophils / immunology
  • Neutrophils / metabolism*
  • Promoter Regions, Genetic
  • Protein Binding
  • Toll-Like Receptor 7 / agonists
  • Toll-Like Receptor 7 / genetics
  • Toll-Like Receptor 7 / metabolism
  • Toll-Like Receptor 8 / agonists
  • Toll-Like Receptor 8 / genetics
  • Toll-Like Receptor 8 / metabolism*
  • Tumor Necrosis Factor-alpha / metabolism
  • Young Adult

Substances

  • CCAAT-Enhancer-Binding Protein-beta
  • Imidazoles
  • Interferon-alpha
  • Interleukin-6
  • Toll-Like Receptor 7
  • Toll-Like Receptor 8
  • Tumor Necrosis Factor-alpha
  • resiquimod