Background Recent studies reported that vascular adventitial fibroblasts (AFs) are involved in the development of vascular inflammatory diseases, such as atherosclerosis. Urotensin II (UII), a potent vasoconstrictive peptide, could stimulate phenotype differentiation and proliferation of the AFs. The goal of this study was to investigate the effect of UII on the expression of monocyte chemoattractant protein-1 (MCP-1) in rat aortic AFs, and to study the signal transduction pathways of it.
Methods Growth-arrested AFs were incubated in serum-free medium with UII (10−10–10−7 mol/l). In order to explore the mechanism of UII effect, the cells were pretreated with some inhibitors of signal transduction pathways for 30 m, and then incubated with UII (10−8 mol/l) for 3 h to 24 h. The MCP-1 mRNA and protein expression induced by UII were evaluated by the reverse transcriptase PCR and Western Blotting, respectively. The MCP-1 secretion from the cells was determined by ELISA.
Results UII could upregulate MCP-1 expression significantly. The MCP-1 mRNA expression increased after 1 h (p<0.05) of UII (10−8 mol/l) treatment and reached a peak at 3 h (p<0.01). It then declined from 6 to 24 h, and there are no significantly differences from 0 h group. UII dose-dependently induced MCP-1 mRNA expression, with maximal effect at a concentration of 10−8 mol/l at 3 h (p<0.01). The MCP-1 mRNA expression was increased by 70.10%, 109.65%, 189.73% and 122.99% in 10−10 mol/l, 10−9 mol/l, 10−8 mol/l and 10−7 mol/l group, respectively, as compared with the control group (without UII stimulation), and the upregulation was significant (p<0.01 in all groups). The effect of UII was inhibited significantly by the UII receptor antagonist SB710411 (10−6 mol/l), Rho protein kinase inhibitor Y27632 (10−5 mol/l), protein kinase C inhibitor H7 (10−5 mol/l), mitogen-activated protein kinase inhibitor PD98059 (10−5 mol/l), calcineurin inhibitor Cyclosporine A (10−5 mol/l) and Ca2+ channel blocker nicardipine (10−5 mol/l), (p<0.01 in all groups). In addition, UII also induced protein expression and secretion of MCP-1 in the cells, both in a dose-dependent and time-dependent manner, with maximal effect at a concentration of 10−8 mol/l at 12 h (in the level of protein secretion from the cells, p<0.01) or 24 h (in the level of protein expression in the cells, p<0.01), which could also be inhibited by these inhibitors (p<0.01 in all groups).
Conclusion Urotensin II may stimulate the expression of monocyte chemoattractant protein-1 in rat aortic adventitial fibroblasts, through its receptor and the Ca2+ channel, protein kinase C, mitogen-activated protein kinase, calcineurin and Rho kinase signal transduction pathways, contributing to the vascular inflammation.