Anaïs Wakx has graduated in Toxicology from the Paris Descartes University, works on the impact of micropollutants, particularly endocrine disruptors and carcinogenic, mutagenic and reprotoxic substances on placenta. She is the recipient of the OPAL Prize awarded by the National Academy of Pharmacy for her work on alternative methods for animal experimentation. Her current work is supported by the French Agency for Food, Environmental and Occupational Health & Safety (ANSES).
Statement of the Problem: Benzo(a)pyrene (BaP) is a persistent environmental pollutant produced by organic combustion from various sources, and is currently classified as highly carcinogenic, mutagenic and reprotoxic substance. Human placenta-an interface between the fetus and the mother plays a critical role as a barrier against many xenobiotics. However, pollutants such as BaP could reach and cross this barrier and thus modify its physiological functions, with significant implications on pregnancy outcome. Within the cell, the main target of BaP is the aryl hydrocarbon receptor (AhR), a cytosolic ligand-activated transcription factor which relocates and triggers the expression of genes involved in xenobiotic metabolism. However, recent data suggest that the AhR is not limited to this process and may assure functions other than detoxification. Our aim was to evaluate the expression, localization and activation of the AhR in several placental models, as well as the impact of BaP exposure toward these parameters. Methodology & Theoretical Orientation: we characterized, for the first time, the expression profile of the AhR and its activity toward its main target genes in human placental chorionic villi during different periods of pregnancy. Using different methods such as cell fractionation and fluorescence microscopy, we unexpectedly demonstrated a nuclear localization of the AhR in 1) freshly harvested chorionic villi throughout pregnancy, 2) purified term placental primary cells during differentiation into syncytiotrophoblast and 3) BeWo cell line in the absence of any exogenous activator, suggesting an intrinsic activation of the AhR. Furthermore, we studied the impact of BaP exposure toward the localization and activity of this receptor in human trophoblast cells. The expression of AhR, its partner ARNT and its repressor AhRR were unaffected. However, we demonstrated a role of the AhR upon BaP exposure (using RT-qPCR) on the expression of various critical genes involved in different processes such as detoxification, placental function, oxidative stress, inflammation, and epithelial to mesenchymal transition. Conclusion & Significance: To our knowledge, this is the first study of a global functional cartography of the AhR in human placenta. Recent Publications 1.Wakx A, Regazzetti A, Dargère D, Auzeil N, Gil S, Evain-Brion D, Laprévote O, Rat P (2016) New in vitro biomarkers to detect toxicity in human placental cells: The example of benzo[A]pyrene. Toxicol. In Vitro 32: 76-85. 2.Stejskalova L, Pavek P (2011) The function of cytochrome P450 1A1 enzyme (CYP1A1) and aryl hydrocarbon receptor (AhR) in the placenta. Curr. Pharm. Biotechnol. 12(5): 715-30.
Anja Mikolić has graduated from the Faculty of Food Technology and Biotechnology, University of Zagreb in 2005. She acquired her PhD in Biomedicine and Health Sciences from the Faculty of Pharmacy and Biochemistry, University of Zagreb in 2015. She is employed in Analytical Toxicology and Mineral Metabolism Unit at Institute for Medical Research and Occupational Health (IMROH), Zagreb, Croatia since 2007. Her professional fields are designing and performing in vivo studies on experimental animals (rats); studying biomarkers of oxidative stress; assessment of human exposure to essential and toxic metals by bio-monitoring, interactions of metals and reproductive toxicity; development and application of analytical methods regarding hormone and antioxidant enzyme analysis. She has published 6 original scientific papers in the international peer-reviewed journals, participated in few national and international scientific conferences and is a member of few scientific associations.
Terbuthylazine is a chlorotriazine herbicide that acts primarily as an inhibitor of photosynthesis. It is used mainly in the production of maize but is also applied in the cultivation of various fruits, and vegetables, as well as in forestry. We evaluated the in vivo effects of terbuthylazine following a 28-day oral administration in adult male Wistar rats at 2.300 mg/kg b.w./day, 0.400 mg/kg b.w./day, and 0.004 mg/kg b.w./day. After treatment, oxidative stress responses were measured in the blood of both the terbuthylazine-treated and the control rats using biomarkers of lipid peroxidation, activities of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and catalase. To establish DNA damaging effects, we applied an alkaline comet assay on the leukocytes of the exposed and control animals. Exposure to terbuthylazine slightly disturbed lipid peroxidation, which was not dose-dependent. Treatment also led to increases of GSH-Px activity in blood, which was statistically significant at 0.400 mg/kg b.w./day. The observed increase of SOD activity in erythrocytes was most prominent at the highest dose tested. On the other hand, plasma SOD activity dropped significantly at two lower doses. Catalase activity in plasma decreased, which was statistically significant at the highest dose. Terbuthylazine produced measurable effects on leukocyte rat DNA. Based on the values measured for comet tail length and tail intensity, which were both lower at the two higher concentrations, it can be concluded that one of possible mechanisms of terbuthylazine’s effect on the DNA molecule includes intercalation. This may in turn slow down the migration of DNA during electrophoresis. Taken together, our findings suggest that the 28-day exposure of rats to very low doses of terbuthylazine, which were within toxicology reference values, resulted in oxidative stress responses and low-level DNA instability. Our results call for further research using other sensitive biomarkers of effect, along with different exposure scenarios.