The effect of nicotine on the production of soluble fms-like tyrosine kinase-1 and soluble endoglin in human umbilical vein endothelial cells and trophoblasts

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 (alpha7 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 alpha7 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 alpha7 nAChR in the nicotinic effect, cells were treated with the alpha7 nAChR antagonist alpha-bungarotoxin (alpha-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 alpha-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 alpha-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 alpha7 nAChR.ope