NF-κB pathway mediates vascular smooth muscle response to nicotine

Vascular smooth muscle cells (SMCs) and endothelial cells (ECs) play important roles in nicotine-induced cardiovascular disease. To elucidate the mechanism underlying the abnormal SMC behavioral response to nicotine, we investigated the activation of the NF-κB signal transduction pathway and cell adhesion molecular (CAM) expression on SMCs. Also we used different cell culture manner of SMC sole and EC-SMC co-culture with a 0.4 or a 3 μm membrane pore, to observe whether there is a crosstalk between EC/SMC involved in the process of NF-κB pathway activation. Nicotine-induced effects were observed in SMCs by both monoculture and co-culture with the 3 μm-pore size, including the phosphorylation of IKK and IκB, the shift of transcription factor NF-κB, and the enhancement of SMC cytoskeleton protein expression and migration ability, but none were observed by co-culture with the 0.4 μm-pore size. All of the actions could be distinctly blocked by α-bungarotoxin (α7 nicotinic receptor inhibitor) or PDTC (NF-κB suppressor). Flow cytometry analysis showed that the adhesion molecules ICAM-1 and LFA-1 and VCAM-1 and VLA-4 were better expressed similarly on the surface of SMCs in the monoculture and 3 μm-pore size co-culture system vs. the 0.4 μm co-culture way. The results imply that nicotine induces SMC cytoskeleton protein up-expression and migration via the NF-κB signaling pathway and that EC-SMC crosstalk via CAM facilitates its response to nicotine.