Human neutrophils contribute to the regulation of inflammation via the generation of a range of cytokines that affect all elements of the immune system. Here, we investigated their ability to express some of the members of the IL-12 family after incubation with TLR8 agonists. Highly pure human neutrophils were thus incubated for up to 48 h with or without R848, or other TLR8 agonists, to then measure the expression levels of transcripts and proteins for IL-12 family member subunits by RNA-seq, reverse transcription quantitative PCR, and ELISA. We show a TLR8-mediated inducible expression of IL-12B and IL-23A, but not IL-12A, mRNA, which occurs via chromatin remodeling (as assessed by ChIP-seq), and subsequent production of IL-23 and IL-12B, but no IL-12, proteins. Induction of IL-23 requires endogenous TNF-alpha, as both mRNA and protein levels were blocked in TLR8-activated neutrophils via a TNF-alpha-neutralizing Ab. We also show that supernatants from TLR8-activated neutrophils, but not autologous monocytes, induce the differentiation of Th17 cells from naive T cells in an IL-23-dependent fashion. This study unequivocally demonstrates that highly pure human neutrophils express and produce IL-23, further supporting the key roles played by these cells in the important IL-17/IL-23 network and Th17 responses.

Human neutrophils activated via TLR8 promote Th17 polarization through IL-23

Tamassia, Nicola;Gardiman, Elisa;Bianchetto-Aguilera, Francisco;Gasperini, Sara;Annunziato, Francesco;Cassatella, Marco A
2019-01-01

Abstract

Human neutrophils contribute to the regulation of inflammation via the generation of a range of cytokines that affect all elements of the immune system. Here, we investigated their ability to express some of the members of the IL-12 family after incubation with TLR8 agonists. Highly pure human neutrophils were thus incubated for up to 48 h with or without R848, or other TLR8 agonists, to then measure the expression levels of transcripts and proteins for IL-12 family member subunits by RNA-seq, reverse transcription quantitative PCR, and ELISA. We show a TLR8-mediated inducible expression of IL-12B and IL-23A, but not IL-12A, mRNA, which occurs via chromatin remodeling (as assessed by ChIP-seq), and subsequent production of IL-23 and IL-12B, but no IL-12, proteins. Induction of IL-23 requires endogenous TNF-alpha, as both mRNA and protein levels were blocked in TLR8-activated neutrophils via a TNF-alpha-neutralizing Ab. We also show that supernatants from TLR8-activated neutrophils, but not autologous monocytes, induce the differentiation of Th17 cells from naive T cells in an IL-23-dependent fashion. This study unequivocally demonstrates that highly pure human neutrophils express and produce IL-23, further supporting the key roles played by these cells in the important IL-17/IL-23 network and Th17 responses.
IL-23; TLR8; TNF-α; Th17 cells; neutrophils
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11562/998104
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