Gestational Age–Dependent Abundance of Human Placental Transporters as Determined by Quantitative Targeted Proteomics

Abstract

Some women take medication during pregnancy to address a variety of clinical conditions. Because of ethical and logistical concerns, it is impossible to determine fetal drug exposure, and therefore fetal risk, during pregnancy. Hence, alternative approaches need to be developed to predict maternal-fetal drug exposure throughout pregnancy. To do so, we previously developed and verified a maternalfetal physiologically based pharmacokinetic model, which can predict fetal exposure to drugs that passively cross the placenta. However, many drugs are actively transported by the placenta (e.g., human immunodeficiency virus protease inhibitors). To extend our maternal-fetal physiologically based pharmacokinetic model to these actively transported drugs, we determined the gestational age-dependent changes in the protein abundance of placental transporters. Total cellular membrane fractions from first trimester (T1; n = 15), second trimester (T2; n = 19), and term (n = 15) human placentae obtained from uncomplicated pregnancies were isolated by ultracentrifugation. Transporter protein abundance was determined by targeted quantitative proteomics using liquid chromatography tandem mass specrometry. We observed that breast cancer resistance protein and P-glycoprotein abundance significantly decreased from T1 to term by 55% and 69%, respectively (per gram of tissue). Organic anion-transporting polypeptide (OATP) 2B1 abundance significantly decreased from T1 to T2 by 32%. In contrast, organic cation transporter (OCT) 3 and organic anion transporter 4 abundance significantly increased with gestational age (2-fold from T1 to term, 1.6-fold from T2 to term). Serotonin transporter and norepinephrine transporter did not change with gestational age. The abundance of bile salt export pump, multidrug resistance-associated protein 1-5, Na +-taurocholate cotransporting polypeptide, OATP1B1, OATP1B3, OCTN1-2, concentrative nucleoside transporter 1-3, equilibrative nucleoside transporter 2, and multidrug and toxin extrusion 1 could not be quantified. These data can be incorporated into our maternal-fetal physiologically based pharmacokinetic model to predict fetal exposure to drugs that are actively transported across the placenta. SIGNIFICANCE STATEMENT We quantified the protein abundance of key placental uptake and efflux transporters [organic cation transporter (OCT) 3, P-glycoprotein (P-gp), breast cancer resistance protein (BCRP)] across gestational ages (first trimester, second trimester, and term) using quantitative targeted proteomics. We observed that the protein abundance of P-gp and BCRP decreased, whereas that of OCT3 increased with gestational age. Incorporating the protein abundance determined in this study into maternal-fetal physiologically based pharmacokinetic model can help us better predict fetal drug exposure to substrates of these transporters.

Exploring the Use of Serum‐Derived Small Extracellular Vesicles as Liquid Biopsy to Study the Induction of Hepatic Cytochromes P450 and Organic Anion Transporting Polypeptides

“…Therefore, reported normal pregnancy-related changes in placental OATP expression, as well as maternal urine (plasma) coproporphyrin, bile acid, and bilirubin profiles, may be independent of maternal liver OATP expression. [42][43][44][45] Nonparametric analysis demonstrated significantly higher CYP2D6 expression in liver sEVs from T3 vs. T0 women (P = 0.03; Figure 5a). Although the study was not powered to undertake a formal parametric assessment, the apparent mean difference in liver sEV-derived CYP2D6 expression between T0 and T3 women (3.7-fold) is comparable to the ~ 3-fold increase proposed by Ke et al 15 in their PBPK of CYP2D6 substrates (T3 vs. postpartum).…”

PBPK Modeling Approach to Predict the Behavior of Drugs Cleared by Kidney in Pregnant Subjects and Fetus

“…This transporter has been identified on the apical membrane of the placenta, limiting the transfer of its substrates into the fetal tissues [60,61]. However, a recent proteomic study could not quantify the amount of this transporter at different stages of pregnancy [62]. Therefore, the effect of MRP4 on CFX and CZ transplacental transfer was captured through the permeability parameters which lumped effect of MRP4 amount and activity in the placenta tissue.…”

Development and Verification of a Linked Δ9-THC/11-OH-THC Physiologically Based Pharmacokinetic Model in Healthy, Nonpregnant Population and Extrapolation to Pregnant Women

“…The magnitude of THC placental active efflux as well as additional mechanisms that may contribute to THC fetal exposure needs to be experimentally characterized. Since the placental expression of P-gp and BCRP varies with gestational age (Anoshchenko et al, 2020), and since prenatal use of THC at different stages of pregnancy can differentially impact neonatal outcomes (Grzeskowiak et al, 2020), it is important to understand the fetal exposure of THC throughout pregnancy. Further investigation into THC and 11-OH-THC placental metabolism and transport (or other reasons for this low F/M ratio) are ongoing in our laboratory to further refine the fetal THC and 11-OH-THC predictions.…”