Assessment of Chlorpyrifos impact on Human Placenta through in-vitro cell models

MAGALI E. RIDANO; ANA C. RACCAA; JÉSICA FLORES-MARTIN; SUSANA GENTI-RAIMONDI; GRACIELA M. PANZETTA-DUTARI

Buenos Aires

Simposio; “Frontiers in BioScience”: Joint Symposium of the Max Planck Society and the Ministry of Science, Technology and Innovation; 2012

Max Planck Society and the MinCyT

Environmental contaminants may alter the normal function of the human placenta affecting pregnancy and/or the fetus and even the adult life of the developing individual. The trophoblasts are the main functional cells of the placenta and their differentiation and function are intimately related to fetal development and maternal health. Extravillous trophoblasts participate in pregnancy immunotolerance, angiogenesis and maternal blood efflux control, among other functions, and villous trophoblasts regulate nutrient, gases and metabolic waste exchange between the mother and fetus. They differentiate into a syncytium layer which acts as a placental barrier protecting the fetus from endogenous and exogenous toxic metabolites that arrive through the maternal blood. An increased risk of pregnancy disorders in women chronically exposed to organophosphate pesticides (OP) has been reported. Moreover, their developmental neurobehavioral outcomes and their consequences in adult life are being widely studied. Herein, we investigated whether Chlorpyrifos (CPF), one of the most widely used OP, has any effect on cellular viability and morphology and on the expression of genes important for placental function. As an initial approach we employed the choriocarcinoma-derived JEG-3 cell line as an in-vitro trophoblast model. In conditions of unaltered cell viability, only a slight increase in fragmented and/or condensed nuclei was observed. However, mRNAs coding for GCM1, a key transcription factor involved in trophoblast differentiation, and for hCG, a trophoblast differentiation marker, were increased when cells were exposed to increasing CPF concentrations (up to 100 M) for 24 and 48 h. Also, intracytoplasmic hCG protein and its secretion were higher in cells treated with CPF. The expression of the ABCG2 efflux transporter, known to affect drug transfer across the placental barrier, was increased in cells exposed to this pesticide. To improve the in-vitro model we purified cytotrophoblasts from term placentas and exposed them to CPF. MTT assays revealed a signal increase in cells treated with CPF during 64h. Morphological differentiation into syncytium-like structures was not interrupted by this toxic. Instead, hCG and the P-gp efflux transporter mRNA levels were increased after 22h and the ABCG2 mRNA level was slightly increased after 64h of culture in the presence of CPF. Interestingly, P-gp levels are much higher in primary trophoblast cells than in JEG-3 cells. In sum, present data support the idea that the human placenta is a target of CPF and they suggest that trophoblast CPF toxicity depends on the genetic background of the cells, especially on the expression of genes implicated in xenobiotic transport and metabolism. We are extending our study in order to investigate if CPF is a P-gp substrate in placenta as it has been described in the intestine. Thus this transporter could have an important role in protecting the fetus from CPF toxicity. Supported by SACyT, CONICET, FONCyT, MinCyT of Córdoba and SECyT-UNC.