Published in:
Open Access
01-12-2018 | Research article
Tofacitinib inhibits granulocyte–macrophage colony-stimulating factor-induced NLRP3 inflammasome activation in human neutrophils
Authors:
Makiko Yashiro Furuya, Tomoyuki Asano, Yuya Sumichika, Shuzo Sato, Hiroko Kobayashi, Hiroshi Watanabe, Eiji Suzuki, Hideko Kozuru, Hiroshi Yatsuhashi, Tomohiro Koga, Hiromasa Ohira, Hideharu Sekine, Atsushi Kawakami, Kiyoshi Migita
Published in:
Arthritis Research & Therapy
|
Issue 1/2018
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Abstract
Background
Granulocyte–macrophage colony-stimulating factor (GM-CSF) has emerged as a crucial cytokine that activates myeloid cells to initiate tissue inflammation. However, the molecular actions of GM-CSF against innate immunity are still poorly characterized. Here, we investigated the in vitro effects of GM-CSF on the activation of human myeloid lineages, neutrophils, and the underlying intracellular signaling mechanism, including inflammasome activation.
Methods
Human neutrophils were stimulated with GM-CSF in the presence or absence of tofacitinib. The cellular supernatants were analyzed for interleukin-1 beta (IL-1β) and caspase-1 by enzyme-linked immunosorbent assay (ELISA) methods. Pro-IL-1β mRNA expressions in human neutrophils were analyzed by real-time polymerase chain reaction. Protein phosphorylation of neutrophils was assessed by Western blot using phospho-specific antibodies.
Results
Stimulation with GM-CSF alone, but not tumor necrosis factor-alpha, was shown to increase the release of IL-1β and cleaved caspase-1 (p20) from human neutrophils. Tofacitinib, which inhibits GM-CSF–induced Janus kinase 2 (Jak2)-mediated signal transduction, completely abrogated GM-CSF–induced IL-1β and caspase-1 (p20) secretion from neutrophils. GM-CSF stimulation also induced pro-IL-1β mRNA expression in neutrophils and induced NLR family pyrin domain-containing 3 (NLRP3) protein expression. Although tofacitinib pretreatment marginally inhibited GM-CSF–induced pro-IL-1β mRNA expression, tofacitinib completely abrogated NLRP3 protein expression in neutrophils.
Conclusions
These results indicate that GM-CSF signaling induces NLRP3 expression and subsequent IL-1β production by affecting neutrophils, which may cause the activation of innate immunity. Therefore, GM-CSF is a key regulator of the NLRP3 inflammasome and IL-1β production by activating innate immune cells. This process can be blocked by tofacitinib, which interferes with JAK/STAT signaling pathways.