Abstract:Aim To explore the effect of urotensin Ⅱ （UⅡ） on expression of interleukin-6 （IL-6） in rat aortic adventitial fibroblast （AF） and its intracellular mechanisms. Methods Growth-arrested AF was incubated in serum-free medium with UⅡ （10－10～10－7 mol/L）. In order to explore the mechanism of UⅡ effects, the cells were pretreated with some inhibitors of signal transduction pathways for 30 min, and then incubated with UⅡ （10－8 mol/L） for 3 h to 24 h. The IL-6 mRNA expression in the cells and secretion from the cells induced by UⅡ were evaluated by reverse transcription polymerase chain reaction （RT-PCR） and enzyme-linked immunosorbent assay （ELISA）, respectively. Results （1）UⅡ significantly increased IL-6 mRNA expression and protein secretion in rat AF, in a concentration-dependent （10－10～10－7 mol/L） and a time-dependent manner, with maximal effect at 10－8 mol/L at 3 h for mRNA expression, or at 24 h for protein secretion （both P<0.01）. （2）The effect of UⅡ was inhibited by SB710411 （10－6 mol/L）, nicardipine （10－5 mol/L）, PD98059 （10－5 mol/L）, H7 （10－5 mol/L）, Y-27632 （10－5 mol/L） and cyclosporine A （CsA） （10－5 mol/L）, the inhibitors of UⅡ receptor, Ca2＋ channel, mitogen activated protein kinase, protein kinase C, Rho kinase, and calcineurin, respectively. Conclusion UⅡ significantly induces IL-6 expression in rat AF, via activation of its receptor, Ca2＋ channel, mitogen activated protein kinase, protein kinase C, Rho kinase and calcineurin signal transduction pathways, indicating that UⅡ induced-IL-6 expression is one of the important mechanisms responsible for accelerated atherosclerosis.
