Endothelin-1 induces interleukin-6 release via acctivation of the transcription factor NF-κB in human vascular smooth muscle cells

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Abstract
The potent vasoconstrictor peptide endothelin-1 (ET-1) has been implicated in the pathophysiology of atherosclerosis and ist complications. Since inflammation of the vessel wall is a hallmark of atherosclerosis, the purpose of the present study was to investigate the influence of ET-1 on cytokine production in human vascular smooth muscle cells (SMC) as a marker of inflammatory cell activation. ET-1 (100 pM – 1 μM) stimulated interleukin-6 (IL-6) secretion from human vascular SMC in a concentration-dependent manner. The ET-A-receptor antagonist BQ-123 (10 μM), but not the ET-B-receptor antagonist BQ-788, inhibited IL-6 release. ET-1 also transiently increased IL-6 mRNA compatible with regulation of IL-6 release at the pretranslational level. Electrophoretic mobility shift assays demonstrated time-and concentration-dependent activation of the proinflammatory transcription factor nuclear factor-κB (NF-κB) in ET-1-stimulated human vascular SMC. A decoy oligodeoxynucleotide bearing the NF-κB binding site inhibited ET-1-stimulated IL-6 release to a great extent suggesting that this transcription factor plays a key role for cytokine production elicited by ET-1. Moreover, the antioxidant pyrrolidine dithiocarbamate (10 μM) inhibited ET-1-induced IL-6 release indicating involvement of reactive oxygen species in ET-1 signaling. ET-1-stimulated IL-6 secretion was also suppressed by diphenylene iodonium (40 μM), an inhibitor of flavon-containing enzymes such as NADH/NADPH oxidase. The results demonstrate the ability of ET-1 to induce an inflammatory response in human vascular SMC. These observations may contribute to a better understanding of the role of ET-1 in inflammatory activation of the vessel wall during atherogenesis.

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