Oxidative mechanisms of IL-4-induced IL-6 expression in vascular endothelium.
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.
Lee
Yong Woo
YW
Laboratory of Vascular Biology, Department of Biomedical Sciences and Pathobiology, School of Biomedical Engineering and Sciences, Virginia Tech, Blacksburg, VA 24061, USA. ywlee@vt.edu
Lee
Won Hee
WH
Kim
Paul H
PH
D000818:Animals; D001011:Aorta / Q000166:cytology; D016718:Arachidonic Acid / Q000378:metabolism; D002478:Cells, Cultured; D003609:Dactinomycin / Q000494:pharmacology; D004579:Electron Transport / Q000502:physiology; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D006801:Humans; D015847:Interleukin-4 / Q000494:pharmacology*; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D010084:Oxidation-Reduction; D017382:Reactive Oxygen Species / Q000378:metabolism; D014969:Xanthine Oxidase / Q000378:metabolism
D015850:Interleukin-6; D017382:Reactive Oxygen Species; D003609:Dactinomycin; D015847:Interleukin-4; D016718:Arachidonic Acid; D014969:Xanthine Oxidase; D019255:NADPH Oxidases