• Yoshiro-Furuya, Makiko
• Sato, Shuzo
• Temmoku, Jumpei
• Watanabe, Hiroshi
• Matsuoka, Naoki
• Migita, Kiyoshi
• Yoshida, Shuhei
• Fujita, Yuya
• Matsumoto, Haruki
• Yokose, Kohei
• Yamada, Shunya

Abstract

<jats:title>Abstract</jats:title><jats:sec><jats:title>Objective</jats:title><jats:p>Interferon-gamma (IFN-γ) is overexpressed in rheumatoid synovium and thought to be involved in the pathogenesis of rheumatoid arthritis (RA). In this study, we examined our hypothesis that IFN-γ activates innate immune cells and upregulates inflammatory cytokines. Peripheral blood neutrophils were stimulated with IFN-γ in the presence or absence of Janus kinase (JAK) inhibitors. Interleukin-6 (IL-6) mRNA and protein expression were analyzed using real-time polymerase chain reaction (PCR) method and enzyme-linked immunosorbent assay. Protein phosphorylation of JAKs or STAT1 was assessed by Western blot using phospho-specific antibodies.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>IFN-γ stimulation induces IL-6 expression in protein and mRNA levels in human neutrophils. Furthermore, IFN-γ stimulation induces JAK1/JAK2 phosphorylation and downstream signal transducer and activator of transcription (STAT) 1 phosphorylation in human neutrophils. Although all JAKi, blocked IFN-γ-induced JAK1.2/STAT1 phosphorylation at higher concentrations (100 nM), baricitinib most efficiently inhibited IFN-γ-induced JAK1.2/STAT1 phosphorylation at lower concentrations (≤ 25 nM). Among these JAKi, baricitinib was the most potent regulator for IFN-γ-induced IL-6 production in human neutrophils. Our data indicate that IFN-γ upregulates IL-6 production via the JAK1/2-STAT1 pathway in human innate immune cells. Furthermore, this IFN-γ-mediated IL-6 induction via JAK/STAT was downregulated by JAKi.</jats:p></jats:sec>

Topics

• impedance spectroscopy
• size-exclusion chromatography