Identification, Quantification, and Functional Characterization of Transporters in Human Placenta, Developing Gut and Fetal Brain

总结

SUMMARY The placenta, often referred to as the “intestine” of the fetus, is an essential organ that controls the exchange of nutrients (including vitamins) and xenobiotics (i.e., dietary supplements and FDA approved drugs) between the mother and her fetus. The fetus can also ingest nutrients and xenobiotics via the digestive tract, so do neonates and infants through breastfeeding after birth. The fetal, neonate, and infant blood-brain barrier (BBB) serves a critical role in protecting the developing brain from xenobiotics and supplying nutrients to the brain. Thus, the placenta, the developing BBB and gut are key organs responsible for nutrient and xenobiotic distribution and absorption impacting early human development and xenobiotic toxicity. Transporters can play an essential role in the absorption, systemic exposure, and tissue distribution of nutrients and xenobiotics in the fetus, neonates, and infants across the placental, intestinal, and blood-brain barriers. Identification and quantification of transporters in these tissue barriers is important for understanding and predicting fetal or neonate/infant uptake of, and exposure to, nutrients and xenobiotics, and hence impacting early development as well as the safe and efficacious use of medications/supplements in these vulnerable populations. While the expression and function of a few ABC transporters in human term placenta, such as P-glycoprotein (P-gp) and Breast Cancer Resistance Protein (BCRP), have been well-delineated, such data are sorely missing for transporters in early gestation placenta, and in the developing gut and BBB during pregnancy and after birth. In this application, we propose to establish a Transporter Elucidation Center (TEC) at the University of Washington that addresses the goals articulated in RFA-HD-23-003. Using quantitative global and targeted proteomics, we will systematically identify and quantify the ontogeny of transporters in the human placenta (from early gestation to term), the developing gut as well as the developing BBB (from early and mid-gestation and after birth). Then, through in vitro (transporter-transfected cells, immunohistochemistry, immunolocalization) and ex vivo (e.g., placental perfusion, intestinal organoids, and iPSC-derived human fetal BBB models) transport studies, we will determine novel substrates, cellular localization, and transport activity of highly abundant transporters in these tissues. Combined, these studies will address a critical knowledge gap in our understanding of transporters that control essential physiological functions and xenobiotic disposition in the developing fetus and neonate/infant. Consequently, the proposed studies will enhance our ability to predict the toxicity or efficacy of xenobiotics and physiological efficacy of nutrients (or lack thereof) in these vulnerable populations.