Title The Association between Smoking and Ectopic Pregnancy: Why Nicotine Is BAD for Your Fallopian Tube

Epidemiological studies have shown that cigarette smoking is a major risk factor for tubal ectopic pregnancy but the reason for this remains unclear. Here, we set out to determine the effect of smoking on Fallopian tube gene expression. An oviductal epithelial cell line (OE-E6/E7) and explants of human Fallopian tubes from non-pregnant women (n = 6) were exposed to physiologically relevant concentrations of cotinine, the principle metabolite of nicotine, and changes in gene expression analyzed using the Illumina Human HT-12 array. Cotinine sensitive genes identified through this process were then localized and quantified in Fallopian tube biopsies from non-pregnant smokers (n = 10) and non-smokers (n = 11) using immunohistochemistry and TaqMan RT-PCR. The principle cotinine induced change in gene expression detected by the array analysis in both explants and the cell line was significant down regulation (P,0.05) of the pro-apoptotic gene BAD. We therefore assessed the effect of smoking on cell turnover in retrospectively collected human samples. Consistent with the array data, smoking was associated with decreased levels of BAD transcript (P,0.01) and increased levels of BCL2 transcript (P,0.05) in Fallopian tube biopsies. BAD and BCL2 specific immunolabelling was localized to Fallopian tube epithelium. Although no other significant differences in levels of apoptosis or cell cycle associated proteins were observed, smoking was associated with significant changes in the morphology of the Fallopian tube epithelium (P,0.05). These results suggest that smoking may alter tubal epithelial cell turnover and is associated with structural, as well as functional, changes that may contribute to the development of ectopic pregnancy. Citation: Horne AW, Brown JK, Nio-Kobayashi J, Abidin HBZ, Adin ZEHA, et al. (2014) The Association between Smoking and Ectopic Pregnancy: Why Nicotine Is BAD for Your Fallopian Tube. PLoS ONE 9(2): e89400. doi:10.1371/journal.pone.0089400 Editor: Hiroyoshi Ariga, Hokkaido University, Japan Received December 5, 2013; Accepted January 22, 2014; Published February 20, 2014 Copyright: 2014 Horne et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: Array studies were funded by the Chief Scientist Office (SCD/02) and the laboratory work was supported by The Cunningham Trust and the MRC (G0802808). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: [email protected]