Exposure to Mancozeb impairs embryo implantation via disrupting embryo- epithelium interaction in vitro trophoblast/endometrial cells co-culture model

Abstract

Study question: Will Mancozeb affect implantation using spheroidendometrium co-culture model? What is the underlying mechanism that Mancozeb affect endometrium receptivity? Summary answer: Mancozeb decreased spheroid attachment onto endometrial epithelial cells in vitro and modulated steroid hormone receptor expression and in turns embryo implantation. What is known already: Mancozeb, is a manganese/zinc containing fungicide belonging to the ethylene bisdithiocarbamate (EBDC) family. Mancozeb has already been classified as a potential endocrine disrupting chemical (EDC), which is reported to modulate androgen and thyroid hormone receptor pathways in recent years. It is widely used in agriculture to protect the fruits, crops and vegetables from fungal diseases. Mancozeb has short half-life (1~3 days) and very low acute mammalian toxicity. However, the role of Mancozeb on human reproductive process especially embryo implantation remains largely unknown. Study design, size, duration: We used the JEG-3 and endometrial adenocarcinoma Ishikawa cells lines to mimic embryo implantation. Methotrexate (5 μM) was used as a positive control. JEG-3 and/or Ishikawa cells were treated with different concentrations of Mancozeb (0.01 μg/ml, 0.1 μg/ml, 1 μg/ml and 3 μg/ml) for 24 or 48 hours. Participants/materials, setting, methods: Total RNA and protein were extracted from Ishikawa and JEG-3 cells. The attachment rate of JEG-3 spheroids and the expression of adhesion molecules (N-catenin and E-cadherin) were measured. The expression of Wnt/β-catenin signaling molecules and steroid receptors (ER, PR and AR) transcripts and proteins in Ishikawa cells were measured by qPCR and Western blotting, respectively. The function role of ERb receptor on implantation was confirmed by inhibitor. Main results and the role of chance: Mancozeb did not suppress cell proliferation at concentration less than 10 μg/ml. Mancozeb (>1 μg/ml) could decrease the attachment rates when both JEG-3 and Ishikawa cells were treated. The decrease in attachment rate was more prominent by treating the Ishikawa than JEG-3 cells only. Mancozeb affected the expression of N-cadherin in JEG-3 but not in Ishikawa cells, and down-regulated ERβ transcript and protein levels in Ishikawa cells. No change was observed for the expression of ERα, PR and AR. To confirm the role of ERβ in embryo implantation, we used highly selective ERβ antagonist PHTPP (10 μM) on Ishikawa cells and found PHTPP could reduce the attachment rate in spheroids attachment assay which indicate the association of ERβ in implantation. However, in Wnt/β-catenin signaling pathway, no significant change was observed under environmental conditions. Limitations, reasons for caution: As Mancozeb has a relative short half-life in the cells and environment, its metabolite ethylene thiourea (ETU) should be evaluated. Present study was laboratory study, data from in vivo studies and concentration of Mancozeb and its metabolite in patient with fertility problem should be investigated. Wider implications of the findings: This study indicates that fungicide Mancozeb could affect implantation process through steroid hormone receptor. Countries with high usage on Mancozeb should be investigated in women with high serum Mancozeb level seeking for infertility treatment since exposure to Mancozeb happens via food chain easily.