Though commonly classified as maternal tissue, the placenta is actually a fetal organ that secretes hormones necessary for development and serves as a buffer from the environment in early pregnancy, according to Jennifer Adibi, Sc.D. She spoke Sept. 7 as part of the NIEHS Keystone Science Lecture Seminar Series.
In her talk, “The Placenta: A Battleground of Viruses, Plastics, and Hormones,” Adibi described using a fusion of epidemiological and basic research to explore how the first-trimester placenta mediates the effects of the maternal environment on both fetal development and the child’s long-term health.
Cultivating a unique research program
Now a faculty member in the University of Pittsburgh Departments of Epidemiology and Obstetrics, Gynecology and Reproductive Sciences, Adibi is one of the few scientists in the world studying how environmental chemicals, particularly phthalates, affect early placental development and help determine fetal health. She has cultivated a research program that combines epidemiology with in vitro lab techniques.
“Going into the lab, I wanted to dive deep,” Adibi explained, “but I didn’t want to dive too deep, where what I was doing was not going to be translatable back to epidemiology and to human pregnancy.”
“The placenta is a newly recognized target for endocrine disrupting chemicals,” said Jerry Heindel, Ph.D., of the NIEHS Population Health Branch. He explained that Adibi’s unique approach sheds light on how chemicals in the environment affect placental function, beyond direct effects on the fetus, to include the effect of placental changes on fetal development.
Placenta — a fetal endocrine organ
The structure and function of the placenta changes over the course of pregnancy, and Adibi has found that certain environmental exposures can have considerable effects during the early stages of development, before the onset of maternal-placental blood flow. Such exposures include endocrine disrupting chemicals (EDCs), like phthalates, which she said enter the human body largely through plastics.
For example, Adibi found that exposure in the first-trimester to mono-benzyl phthalate and mono-n-butyl phthalate affects placental hormones. In vitro models of the early human placenta further indicated different hormonal responses to phthalate exposure between males and females, highlighting the role of the placenta in sex-specific endocrine response.
Extending her focus to long-term effects on fetal health, Adibi suggested that the placenta, as a target for endocrine disruption, may help determine how EDCs affect the developing fetus. “Our approach is … to understand how the placenta influences developmental pathways related to reproduction and brain development,” she said, adding that this method would involve longer term follow-up, including into childhood.
Her future studies will aim to reach a deeper understanding of the early placenta, observing early time points in human development, and ultimately translating that knowledge to prenatal screening, for better monitoring of environmental risks in pregnancy. This work may also provide insights into the complicated ways that infections might affect placental-fetal interactions, which is a particularly relevant step in light of the recent Zika virus outbreak.
“It’s neat to see a young investigator delve into epidemiology and basic research, to do work that no one else is doing, in the area of early placental development and sex differences,” said Thad Schug, Ph.D., from the NIEHS Division of Extramural Research and Training, who hosted Adibi’s talk.
(Emily Mesev is an Intramural Research Training Award postbaccalaureate fellow in the NIEHS Intracellular Regulation Group.)