Submitted on July 17, 2006
Accepted on May 17, 2007
The Effect of Cigarette Smoke on Placental Antioxidant Enzyme Expression
Elizabeth H Sidle1, Richard Casselman2, and Graeme N. Smith3*
1 Anatomy and Cell Biology, Queen's University, Kingston, Canada
2 Anatomy & Cell Biology, Queen's University, Kingston, Canada
3 Obstetrics and Gynaecology, Queen's University, Kingston,, Canada
* To whom correspondence should be addressed. E-mail: gns{at}post.queensu.ca.
Cigarette smoking, due to systemic oxidative stress, results in the upregulation of antioxidant systems (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and haeme oxygenase (HO)) in some tissues but the response in the human placenta is unknown. The aim of this study was to determine the effect of cigarette smoke exposure on placental antioxidant expression in vivo and in vitro in the HTR-8SVNeo trophoblast cell line. Methods: Normal term placentas were obtained following elective caesarean section. The chorionic villi (CV), anchoring villi (AV) and basal plate (BP) were dissected and western blot analysis was carried out for HO-1, HO-2, SOD, CAT, and GPx. A cigarette smoke extract (CSE) was prepared, diluted to 0.5, 1 and 2% concentrations, and incubated with HTR-8SVNeo cells for 48 hours. Western blots were carried out for HO-1, HO-2, SOD, and CAT. Results: HO-1 and HO-2 expression was increased in the BP of placentas from smokers compared to non-smokers. CAT, GPx, and SOD levels in all placental regions, and HO-1 and HO-2 expression in the AV and CV were unchanged. Treatment of HTR-8SVNeo cells with CSE dose-dependently increased HO-1 expression only. Conclusions: Cigarette smoke exposure increases HO-1 and HO-2 expression in the placental basal plate and HO-1 expression in the HTR-8SVNeo cells. This may increase the local production of the antioxidants biliverdin and bilirubin, the products of haeme metabolism. This could function to reduce the oxidative damage in the pre-eclamptic (PE) placenta, and may contribute to the observed decreased incidence of PE in smokers.
