• Dan Lu, Fen Peng, Jun Li, Jing Zhao, Xiaojin Ye, Binghan Li, and Wenhui Ding.
• Department of Cardiology, Peking University First Hospital, Beijing, China.
• Arch Med Sci. 2019 Jul 1; 15 (4): 1065-1072.

IntroductionUrotensin II (UII) is an important vasoactive peptide involved in the pathogenesis of atherosclerosis. Monocytes/macrophages play important roles in every step of atherosclerosis. Although UII has a chemoattractant effect on monocytes, it is unclear whether UII regulates inflammatory responses in macrophages. The present study sought to explore whether UII can promote leukotriene B4 (LTB4) production by macrophages.Material And MethodsThe mRNA expression level of LTB4 and 5-lipoxygenase were determined by real-time polymerase chain reaction. The protein level of LTB4 and 5-lipoxygenase expression was assayed by enzyme-linked immunosorbent assay and Western blot, respectively. Western blot analysis was also employed to determine the phosphorylated forms of Akt. Reactive oxygen species (ROS) level was detected by the fluorescent probe 2',7'-dichlorofluorescin diacetate and fluorescence intensity was measured with a multiwell fluorescence plate reader.ResultsUrotensin II promoted LTB4 release and increased 5-lipoxygenase expression in a concentration- and time-dependent manner in RAW264.7 cells. Leukotriene B4 production and 5-lipoxygenase expression were decreased by blocking the UII receptor (UT) with urantide, eliminating ROS with N-acetylcysteine and diphenyliodonium, and inhibiting Akt phosphorylation with LY294002. UII significantly elevated ROS production, whereas urantide, N-acetylcysteine and diphenyliodonium substantially attenuated this effect. UII also enhanced Akt phosphorylation significantly, and this effect was potently inhibited by urantide, N-acetylcysteine, diphenyliodonium and LY294002.ConclusionsUrotensin II may promote 5-lipoxygenase expression and LTB4 release in RAW264.7 macrophages via UT-ROS-Akt pathways. These results indicate that UII may participate in macrophage activation and suggest a potential new mechanism underlying atherosclerosis.

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