Granulocytes are unresponsive to IL-6 due to an absence of gp130

AN Wilkinson, KH Gartlan, G Kelly… - The Journal of …, 2018 - journals.aai.org
AN Wilkinson, KH Gartlan, G Kelly, LD Samson, SD Olver, J Avery, N Zomerdijk, SK Tey
The Journal of Immunology, 2018journals.aai.org
IL-6 mediates broad physiological and pathological effects through its receptor signal
transducing unit gp130. Due to the reportedly wide cellular expression of gp130, IL-6 is
thought to signal ubiquitously via gp130 complex formation with membrane-bound IL-6Rα or
soluble IL-6Rα. gp130 signaling primarily induces p-STAT3 and p-STAT1. In contrast to the
previous dogma, we show in this article that circulating mouse and human granulocytes are
unable to induce p-STAT3 or p-STAT1 after stimulation with IL-6 or an IL-6/soluble IL-6R …
Abstract
IL-6 mediates broad physiological and pathological effects through its receptor signal transducing unit gp130. Due to the reportedly wide cellular expression of gp130, IL-6 is thought to signal ubiquitously via gp130 complex formation with membrane-bound IL-6Rα or soluble IL-6Rα. gp130 signaling primarily induces p-STAT3 and p-STAT1. In contrast to the previous dogma, we show in this article that circulating mouse and human granulocytes are unable to induce p-STAT3 or p-STAT1 after stimulation with IL-6 or an IL-6/soluble IL-6R complex. Furthermore, we demonstrate that this is due to a lack of gp130 expression on mouse and human granulocytes, despite their expression of membrane-bound IL-6R. Importantly, the absence of gp130 is not only a feature of mature granulocytes in healthy individuals, it is also observed after allogeneic stem cell transplantation. Moreover, granulocyte gp130 expression is lost during maturation, because granulocyte-monocyte progenitor cells express gp130 and respond to IL-6. Given that granulocytes constitute 50–70% of circulating leukocytes, this indicates a significantly smaller scope of IL-6 signaling than previously anticipated and has important implications for therapeutic IL-6 inhibition and the mechanisms of action thereof.
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