Nicotine Suppresses the Invasiveness of Human Trophoblasts by Downregulation of CXCL12 Expression through the Alpha-7 Subunit of the Nicotinic Acetylcholine Receptor

Jing Chen,Xiaohong Li,Jian Zhuang,Sheng Wang,Min Qiu,Chengbin Zhou,Jimei Chen,Yanji Qu,Zirui Huang,Fengzhen Han

doi:10.1007/s43032-019-00095-4

Abstract

Smoke exposure during pregnancy has detrimental effects upon numerous fetal and neonatal outcomes. Nicotine (the main component of tobacco) has been suggested to affect placental development. During placental development, efficient invasion by trophoblasts is required for establishment of the fetus–maternal circulation. In this study we explored the regulation of trophoblast invasion by nicotine. An immortalized first trimester extravillous trophoblast cell line (HTR-8/SVneo cells) was used for all the experiments, which were treated by nicotine, methyllycaconitine, and C-X-C motif chemokine ligand 12 (CXCL12). Total RNA and protein were used to study the expressions of nicotinic acetylcholine receptors (nAChRs), and transwell assay was used to study invasiveness. Changes of RNA expression due to nicotine treatment were detected by RNA sequence. Level of CXCL12 mRNA was verified by quantitative PCR. We showed that HTR-8/SVneo expressed subunits α2–4, α7, α9, β1, and β2 of nAChRs. Nicotine downregulated CXCL12 expression and inhibited trophoblast invasion. Methyllycaconitine, as an antagonist of the α7 homopolymer, blocked the inhibitory effect of nicotine. CXCL12 could rescue the nicotine-induced inhibitory effect on invasion of HTR-8/SVneo cells. These results suggest that the α7 subunit of the nAChR has important roles in modulating trophoblast invasion through CXCL12.

Highlights

Maternal exposure to environmental tobacco smoke (ETS) has been shown to be an important risk factor for pregnancy complications in several epidemiology studies [1, 2]
At the mRNA level, the nicotinic acetylcholine receptors (nAChRs) subunits α3, α5, α6, α7, α9, α10, β1, and β2 were expressed in HTR-8/SVneo cells
Analyses of reversetranscribed mRNA for all nAChR subunits tested resulted in expression of α3, α5, α6, α7, α9, α10, β1, and β2 subunits, but not of α1, α2, α4, β3, β4, δ, or ε subunits, in human HTR-8/SVneo cells

Summary

Introduction

Maternal exposure to environmental tobacco smoke (ETS) has been shown to be an important risk factor for pregnancy complications in several epidemiology studies [1, 2]. The negative effects of ETS during pregnancy are abruptio placenta, placenta previa, and intrauterine growth restriction, as well as an increased risk of heart, breathing, and brain abnormalities in the fetus [3,4,5]. A reduction in the diameter of chorionic villi within the placenta, abnormal apoptosis of trophoblast cells, calcification, DNA methylation, and arterial resistance in the umbilical cord can occur with ETS exposure [6,7,8,9,10]. Nicotine binds to nicotinic acetylcholine receptors (nAChRs). NAChRs belong to the cys-loop family of ligand-gated ion channels and include 16 subunits (α1–10, β1–4, δ, ε, and γ) in mammals [12] Nicotine binds to nicotinic acetylcholine receptors (nAChRs). nAChRs belong to the cys-loop family of ligand-gated ion channels and include 16 subunits (α1–10, β1–4, δ, ε, and γ) in mammals [12]

Methods

Results

Conclusion