Abstract
Objectives. To evaluate the effect of nicotine on the production of soluble fms-like tyrosine kinase-1 (sFlt-1) and soluble endoglin (sEng) in human umbilical vein endothelial cells (HUVECs) and trophoblast cells, and to assess the involvement of alpha 7 nicotinic acetylcholine receptor (α7 nAChR) in this process. Methods. Commercially available full-term placental trophoblasts and HUVECs derived from the umbilical cord of a normal pregnancy were used. The expression of α7 nAChR was assessed by immunostaining, RT-PCR, and western blotting. The expression of sFlt-1 and sEng protein in the cell media after 6 and 24 hours of treatment with nicotine was evaluated using a commercially available ELISA. To determine the involvement of α7 nAChR in the nicotinic effect, cells were treated with the α7 nAChR antagonist α-bungarotoxin (α-BGT) prior to the nicotine exposure. Levels of significance were determined using the Student's t-test and one-way ANOVA, and a p-value < 0.05 was considered significant. Main outcome measures. The levels of sFlt-1 and sEng protein were evaluated before and after the nicotine treatment with or without α-BGT pre-treatment. Results. In trophoblast cells, a significant reduction of sFlt-1 and sEng protein was observed after 24 hours of nicotine treatment as compared to the untreated group (p = 0.002, 0.000). In HUVECs, nicotine only had a suppressive effect on the expression of sEng at 6 hours (p = 0.03); there was no effect on sFlt-1 expression. However, pre-treatment with α-BGT did not reverse the nicotine-induced suppressive effect on the expression of sFlt-1 and sEng in trophoblasts and HUVECs. Conclusions. Nicotine reduced the production of sFlt-1 and sEng in trophoblasts and sEng in HUVECs. This effect was not mediated by α7 nAChR.
Acknowledgements
The authors wish to thank Yong Son Maeng, Moung Hwa Kang, and Jeong Hye Hwang for technical assistance.
Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.