Activities of metabolizing enzymes in human placenta

Aspirin increases estrogen levels in the placenta to prevent preeclampsia by regulating placental metabolism and transport function

Preeclampsia is a unique multisystem progressive disease during pregnancy, which seriously endangers the health of pregnant women and fetuses. In clinical practice, aspirin is recommended for the prevention of preeclampsia, but the mechanism by which aspirin prevents preeclampsia has not yet been revealed. This report comprehensively evaluates the effects of aspirin on the expression and activity of placental metabolic enzymes and transporters. We found that after aspirin administration, only the expression of organic anion transporter 4 (OAT4) in the placenta showed a significant increase at both mRNA and protein levels, consistent with the results in JAR cells. Meanwhile, studies on the metabolic enzyme activity in the placenta showed a high upregulation of CYP19A1 activity. Subsequently, significant increases in endogenous substrates of OAT4 and CYP19A1 (dehydroepiandrosterone sulfate (DHEAS) and androstenedione) as well as estrone were detected in placental tissue. In summary, aspirin enhances the transport of DHEAS through OAT4 and promotes the metabolism of androstenedione through CYP19A1, thereby increasing estrogen levels in the placenta. This may be the mechanism by which aspirin prevents preeclampsia and maintains pregnancy by regulating the metabolism and transport function of the placenta.

Fetus Exposure to Drugs and Chemicals: A Holistic Overview on the Assessment of Their Transport and Metabolism across the Human Placental Barrier

BACKGROUND

The placenta exerts a crucial role in fetus growth and development during gestation, protecting the fetus from maternal drugs and chemical exposure. However, diverse drugs and chemicals (xenobiotics) can penetrate the maternal placental barrier, leading to deleterious, adverse effects concerning fetus health. Moreover, placental enzymes can metabolize drugs and chemicals into more toxic compounds for the fetus. Thus, evaluating the molecular mechanisms through which drugs and chemicals transfer and undergo metabolism across the placental barrier is of vital importance. In this aspect, this comprehensive literature review aims to provide a holistic approach by critically summarizing and scrutinizing the potential molecular processes and mechanisms governing drugs and chemical transfer and metabolism across the placental barrier, which may lead to fetotoxicity effects, as well as analyzing the currently available experimental methodologies used to assess xenobiotics placental transfer and metabolism.

METHODS

A comprehensive and in-depth literature review was conducted in the most accurate scientific databases such as PubMed, Scopus, and Web of Science by using relevant and effective keywords related to xenobiotic placental transfer and metabolism, retrieving 8830 published articles until 5 February 2024. After applying several strict exclusion and inclusion criteria, a final number of 148 relevant published articles were included.

RESULTS

During pregnancy, several drugs and chemicals can be transferred from the mother to the fetus across the placental barrier by either passive diffusion or through placental transporters, resulting in fetus exposure and potential fetotoxicity effects. Some drugs and chemicals also appear to be metabolized across the placental barrier, leading to more toxic products for both the mother and the fetus. At present, there is increasing research development of diverse experimental methodologies to determine the potential molecular processes and mechanisms of drug and chemical placental transfer and metabolism. All the currently available methodologies have specific strengths and limitations, highlighting the strong demand to utilize an efficient combination of them to obtain reliable evidence concerning drug and chemical transfer and metabolism across the placental barrier. To derive the most consistent and safe evidence, in vitro studies, ex vivo perfusion methods, and in vivo animal and human studies can be applied together with the final aim to minimize potential fetotoxicity effects.

CONCLUSIONS

Research is being increasingly carried out to obtain an accurate and safe evaluation of drug and chemical transport and metabolism across the placental barrier, applying a combination of advanced techniques to avoid potential fetotoxic effects. The improvement of the currently available techniques and the development of novel experimental protocols and methodologies are of major importance to protect both the mother and the fetus from xenobiotic exposure, as well as to minimize potential fetotoxicity effects.

Establishment of LC-MS/MS method for quantifying chlorpromazine metabolites with application to its metabolism in liver and placenta microsomes

Chlorpromazine has sedative and antiemetic pharmacological effects and is widely used in clinic. Its main metabolites include 7-hydroxychlorpromazine, N-monodesmethylchlorpromazine and chlorpromazine sulfoxide, which affect the therapeutic efficacy. To support metabolism research, the quantitative analysis method of 7-hydroxychlorpromazine, N-monodesmethylchlorpromazine and chlorpromazine sulfoxide in microsomal enzymes was established for the first time by LC-MS/MS. This method has been fully validated in rat liver microsomes, and partially verified in human liver microsomes and human placenta microsomes. The intra-day and inter-day accuracy and precision of the analytes were all within ± 15%. The extraction recovery was good, and no matrix effect was detected. This accurate and sensitive method was successfully applied to chlorpromazine metabolism in different microsomal enzymes. In particular, the biotransformation of chlorpromazine in human placenta microsomes was detected for the first time. The metabolites detected in human liver and placenta microsomes presented different formation rates, indicating the wide distribution and different activities of drug-metabolizing enzymes.

Prenatal Exposition to Different Immunosuppressive Protocols Results in Vacuolar Degeneration of Hepatocytes

Immunosuppressive drugs are essential for transplant recipients, since they prolong proper function of graft; however, they affect the morphology and function of organs, including liver. One commonly observed alteration in hepatocytes is vacuolar degeneration. Numerous medications are contraindicated in pregnancy and breastfeeding, mostly due to a lack of data concerning their advert effects. The aim of the current study was to compare the effects of prenatal exposition to different protocols of immunosuppressants on vacuolar degeneration in the hepatocytes of livers of rats. Thirty-two livers of rats with usage of digital analysis of the images were examined. Area, perimeter, axis length, eccentricity and circularity regarding vacuolar degeneration were analysed. The most prominent vacuolar degeneration in hepatocytes in the aspects of presence, area and perimeter was observed in rats exposed to tacrolimus, mycophenolate mofetil and glucocorticoids, and cyclosporine A, everolimus with glucocorticoids.This is the first study that demonstrates the results of the influence of multidrug immnunosuppression distributed in utero on the hepatic tissue of offspring.

Altered activities of CYP1A1 and CYP19A1 enzymes in women using SSRI medication during pregnancy

INTRODUCTION

Selective serotonin reuptake inhibitors (SSRIs) are commonly used medication for the treatment of depression during pregnancy. Their use may affect various biological molecules such as enzymes which regulate placental hormonal production and xenobiotic metabolism. Our aim was to investigate the effect of maternal SSRI use on activities of three placental enzymes.

METHODS

We analyzed activities of xenobiotic metabolism enzymes cytochrome P450 1A1 (CYP1A1), aromatase (CYP19A1), and glutathione-S-transferase (GST) from placental microsomal and cytosolic subcellular fractions. Term placentas were collected from 47 SSRI users and 49 control women participating Kuopio Birth cohort (KuBiCo) during the years 2013-2015. Among SSRI users, escitalopram was the most widely used SSRI medication.

RESULTS

The mean enzyme activities of all studied enzymes were lower in SSRI users compared to controls. A statistically significant difference was observed in the enzyme activities of CYP19A1 (p = 0.001) and CYP1A1 (p = 0.002) between the study groups after adjusting for use of additional medication, gestational diabetes, sex of the newborn and gestational weeks at delivery. SSRI use had no significant effect on placental GST enzyme activity.

DISCUSSION

Our results indicate that SSRI medication alters placental enzyme activities. This may lead disturbances in maternal steroid hormone balance as well as in xenobiotic metabolism and may provide risk for both developing fetus and pregnant women.

Predicting Human Fetal Drug Exposure Through Maternal-Fetal PBPK Modeling and In Vitro or Ex Vivo Studies

Medication (drug) use in human pregnancy is prevalent. Determining fetal safety and efficacy of drugs is logistically challenging. However, predicting (not measuring) fetal drug exposure (systemic and tissue) throughout pregnancy is possible through maternal-fetal physiologically based pharmacokinetic (PBPK) modeling and simulation. Such prediction can inform fetal drug safety and efficacy. Fetal drug exposure can be quantified in 2 complementary ways. First, the ratio of the steady-state unbound plasma concentration in the fetal plasma (or area under the plasma concentration-time curve) to the corresponding maternal plasma concentration (ie, Kp,uu ). Second, the maximum unbound peak (Cu,max,ss,f ) and trough (Cu,min,ss,f ) fetal steady-state plasma concentrations. We (and others) have developed a maternal-fetal PBPK model that can successfully predict maternal drug exposure. To predict fetal drug exposure, the model needs to be populated with drug specific parameters, of which transplacental clearances (active and/or passive) and placental/fetal metabolism of the drug are critical. Herein, we describe in vitro studies in cells/tissue fractions or the perfused human placenta that can be used to determine these drug-specific parameters. In addition, we provide examples whereby this approach has successfully predicted systemic fetal exposure to drugs that passively or actively cross the placenta. Apart from maternal-fetal PBPK models, animal studies also have the potential to estimate fetal drug exposure by allometric scaling. Whether such scaling will be successful is yet to be determined. Here, we review the above approaches to predict fetal drug exposure, outline gaps in our knowledge to make such predictions and map out future research directions that could fill these gaps.

Effect of Ethanol Consumption on the Placenta and Liver of Partially IGF-1-Deficient Mice: The Role of Metabolism via CYP2E1 and the Antioxidant Enzyme System

Simple Summary

Ethanol is the most consumed drug worldwide, even during pregnancy. One of its adverse outcomes is fetal growth restriction, an alteration in development due to decreased IGF-1 levels. Several studies have shown that ethanol can impair the IGF-1 signaling pathway, thus exacerbating IGF-1 adverse effects in both intrauterine and postnatal growth and development. In this manuscript, we used a partially IGF-1-deficient mouse model to demonstrate the key role of IGF-1 in fetal development, as well as ethanol’s adverse effects on CYP2E1 expression levels and the antioxidant enzyme system during pregnancy.

Abstract

Ethanol use during pregnancy is a risk factor for developing adverse outcomes. Its metabolism by cytochrome P450 2E1 (CYP2E1) produces radical oxygen species (ROS), promoting cellular injury and apoptosis. To date, no studies have been conducted to elucidate the teratogenic effects due to both IGF-1 deficiency and ethanol consumption in mice placentas. The aim of this study is to determine the effect of ethanol consumption on the placenta and liver of partially IGF-1-deficient mice, the role of metabolism via CYP2E1, and the antioxidant enzyme system. Heterozygous (HZ, Igf1^+/−) pregnant female mice were given water or 10% ethanol. Wild-type (WT, Igf1^+/+) female mice were used as controls. At gestational day 19, pregnant dams were euthanized, and maternal liver and placentas were collected. Pregnant HZ dams were smaller than controls, and this effect was higher due to ethanol consumption. Cyp2e1 gene was overexpressed in the liver of HZ pregnant dams exposed to ethanol; at the protein level, CYP2E1 is reduced in placentas from all genotypes. The antioxidant enzymatic system was altered by ethanol consumption in both the maternal liver and placenta. The results in this work hint that IGF-1 is involved in intrauterine development because its deficiency exacerbates ethanol’s effects on both metabolism and the placenta.

The Placenta as a Target for Alcohol During Pregnancy: The Close Relation with IGFs Signaling Pathway

Alcohol is one of the most consumed drugs in the world, even during pregnancy. Its use is a risk factor for developing adverse outcomes, e.g. fetal death, miscarriage, fetal growth restriction, and premature birth, also resulting in fetal alcohol spectrum disorders. Ethanol metabolism induces an oxidative environment that promotes the oxidation of lipids and proteins, triggers DNA damage, and advocates mitochondrial dysfunction, all of them leading to apoptosis and cellular injury. Several organs are altered due to this harmful behavior, the brain being one of the most affected. Throughout pregnancy, the human placenta is one of the most important organs for women's health and fetal development, as it secretes numerous hormones necessary for a suitable intrauterine environment. However, our understanding of the human placenta is very limited and even more restricted is the knowledge of the impact of toxic substances in its development and fetal growth. So, could ethanol consumption during this period have wounding effects in the placenta, compromising proper fetal organ development? Several studies have demonstrated that alcohol impairs various signaling cascades within G protein-coupled receptors and tyrosine kinase receptors, mainly through its action on insulin and insulin-like growth factor 1 (IGF-1) signaling pathway. This last cascade is involved in cell proliferation, migration, and differentiation and in placentation. This review tries to examine the current knowledge and gaps in our existing understanding of the ethanol effects in insulin/IGFs signaling pathway, which can explain the mechanism to elucidate the adverse actions of ethanol in the maternal-fetal interface of mammals.