Oxidative mechanisms of IL-4-induced IL-6 expression in vascular endothelium

Cytokine. 2010 Jan;49(1):73-9. doi: 10.1016/j.cyto.2009.08.009. Epub 2009 Oct 12.

Abstract

The present study is designed to investigate the effects of interleukin-4 (IL-4) on expression of interleukin-6 (IL-6), as well as to examine the role of distinct sources of reactive oxygen species (ROS) in this process. Real-time reverse transcriptase-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) showed that IL-4 significantly up-regulated the mRNA and protein expression of IL-6 in human aortic endothelial cells (HAEC) and C57BL/6 mice. Dihydroethidium (DHE) and dichlorofluorescein (DCF) fluorescence staining demonstrated that IL-4 significantly increased ROS generation in HAEC. A significant and dose-dependent inhibition of IL-4-induced IL-6 expression was observed in HAEC pre-treated with antioxidants, such as pyrrolidine dithiocarbamate (PDTC) and epigallocatechin gallate (EGCG), indicating that IL-4-induced IL-6 expression is mediated via an ROS-dependent mechanism. Additionally, pharmacological inhibitor of NADPH oxidase (NOX) significantly attenuated IL-4-induced ROS generation and IL-6 expression in HAEC. Furthermore, the disruption of NOX gene dramatically and significantly reduced IL-4-induced IL-6 expression in NOX knockout mice (B6.129S6-Cybb(tm1Din)/J). In contrast, overexpression of IL-6 in IL-4-activated HAEC was not affected by inhibiting other ROS generating pathways, such as xanthine oxidase, arachidonic acid metabolism, and the mitochondrial electron transport chain. These results demonstrate that IL-4 up-regulates IL-6 expression in vascular endothelium through NOX-mediated ROS generation.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Aorta / cytology
  • Arachidonic Acid / metabolism
  • Cells, Cultured
  • Dactinomycin / pharmacology
  • Electron Transport / physiology
  • Endothelium, Vascular / cytology
  • Endothelium, Vascular / drug effects*
  • Endothelium, Vascular / metabolism*
  • Humans
  • Interleukin-4 / pharmacology*
  • Interleukin-6 / genetics
  • Interleukin-6 / metabolism*
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • NADPH Oxidases / antagonists & inhibitors
  • NADPH Oxidases / genetics
  • NADPH Oxidases / metabolism
  • Oxidation-Reduction
  • Reactive Oxygen Species / metabolism
  • Xanthine Oxidase / metabolism

Substances

  • Interleukin-6
  • Reactive Oxygen Species
  • Dactinomycin
  • Interleukin-4
  • Arachidonic Acid
  • Xanthine Oxidase
  • NADPH Oxidases