| Background: Urotensin II (Uâ…¡) is an neural cyclic peptide hormone,which is the most potent vasocontractive peptide known so far. It has a wide range of biological functions, such as vasoconstriction, promoting cell proliferation and promoting foam cell formation. In addition, it is also involved in vascular inflammation, involved in a variety of cardiovascular diseases. Studies have determind that the inflammatory mechanism is one of the most important pathogenesis of atherosclerotic disease. Interleukin -6 (IL-6) is one of the inflammatory cytokines, and plays an irreplaceable role in the inflammatory response. Therefore, it is important to detrmine the relationship of urotensin II and IL -6 for clarification of new mechanism of vascular inflammation, such as atherosclerosis and other vascular diseases. Objective To explore the effect of Uâ…¡on the expression of IL-6 in rat aortic adventitial fibroblasts (AFs) , and the possible intracellular signal transduction pathways.Methods The adventitia from thoracic aorta of male Sprague–Dawley rats was isolated and cultured in vitro with DMEM medium containing 20% fetal calf serum to obtain the adventitial fibroblasts(AFs) , and passage 3–5 AFs were used for experiments after incubation with serum-free medium for 24h. Cultured cells were separated into (1)Control group: Cells were cultured in serum-free DMEM and absence of Uâ…¡; (2)Uâ…¡group: different concentration(10-10,10-9,10-8 and 10-7mol/L) and hours(1h,3h,6h,12h,24h) of Uâ…¡stimulation; (3)Uâ…¡+ inhibitors group: Cells were pretreated in DMEM for 0.5 h with Uâ…¡receptor antagonist SB710411(10-6M), Ca2+ channel blocker nicardipine (10-5M), mitogen activated protein kinase(MAPK) inhibitor PD98059 (10-5M), protein kinase C (PKC) inhibitor H7 (10-5M), Rho protein kinase inhibitor Y-27632 (10-5M) or calcineurin inhibitor Cyclosporine A(CSA) (10-5M), followed by Uâ…¡(10-8 mol/L). The cells and medium were collected respectively after incubation. The mRNA and protein expression of IL-6 in rat AFs induced by Uâ…¡were examined by semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay(ELISA), respectively.Results Uâ…¡induced IL-6 expression significantly in rat aortic adventitial fibroblasts. (1)Uâ…¡incduced a dose-dependent increase in IL-6 mRNA expression and protein secretion, compare with control group, AFs IL-6 mRNA was increased by 83.7%(P<0.01),89.6%(P<0.01),166.6%(P<0.01)and 64.1%(P<0.05)in 10- 10, 10-9, 10-8 and 10-7mol/L Uâ…¡group, respectively. The IL-6 protein secretion was increased by 9.86%(P<0.05),20.28%(P<0.01),24.84%(P< 0.01)å'Œ21.31%(P<0.01) in 10- 10,10-9,10-8 and 10-7mol/L Uâ…¡group, respectively. (2)Uâ…¡(10-8 mol/L) incduced a time-dependent increase in IL-6 mRNA expression and protein secretion, compare with control group, AFs IL-6 mRNA was increased by 72.7%(P<0.01),98.0%(P<0.01),59.6%(P<0.01),35.9%(P>0.05)and 30.5%(P<0.05)in 1h, 3h, 6h, 12h and 24h group, respectively. The IL-6 protein secretion was increased by 32.49%(P < 0.05)and 58.49%(P<0.01)in 12h, 24h group , respectively. (3)This effect of Uâ…¡was inhibited by SB710411, nicardipine, PD98059,H7, Y-27632 and CSA. The expression of IL-6 mRNA was inhibited by 23.38%(P<0.01),17.23%(P < 0.05),57.56%(P<0.01),32.94%(P<0.01),40.08%(P<0.01)and 28.84%(P<0.01),and the IL-6 protein secretion was inhibited by 18.95%,16.50%,15.62%,17.32%,21.32% and 18.96%(P<0.01)compare with control group, respectively .Conclusion Uâ…¡could induce IL-6 expression in rat AFs through its recptor and the Ca2+ channel, mitogen activated protein kinase, protein kinase C, Rho kinase, and calcineurin signal transduction pathways, contributing to the development of vascular remodeling by promotion of vascular inflammation. |
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