The effect of maternal obesity on the expression and functionality of placental P-glycoprotein: Implications in the individualized transplacental digoxin treatment for fetal heart failure

Obesity-induced blood-brain barrier dysfunction: phenotypes and mechanisms

Obesity, a burgeoning global health issue, is increasingly recognized for its detrimental effects on the central nervous system, particularly concerning the integrity of the blood-brain barrier (BBB). This manuscript delves into the intricate relationship between obesity and BBB dysfunction, elucidating the underlying phenotypes and molecular mechanisms. We commence with an overview of the BBB's critical role in maintaining cerebral homeostasis and the pathological alterations induced by obesity. By employing a comprehensive literature review, we examine the structural and functional modifications of the BBB in the context of obesity, including increased permeability, altered transport mechanisms, and inflammatory responses. The manuscript highlights how obesity-induced systemic inflammation and metabolic dysregulation contribute to BBB disruption, thereby predisposing individuals to various neurological disorders. We further explore the potential pathways, such as oxidative stress and endothelial cell dysfunction, that mediate these changes. Our discussion culminates in the summary of current findings and the identification of knowledge gaps, paving the way for future research directions. This review underscores the significance of understanding BBB dysfunction in obesity, not only for its implications in neurodegenerative diseases but also for developing targeted therapeutic strategies to mitigate these effects.

Obesity in pregnancy-Long-term effects on offspring hypothalamic-pituitary-adrenal axis and associations with placental cortisol metabolism: A systematic review

Obesity, affecting one in three pregnant women worldwide, is not only a major obstetric risk factor. The resulting low-grade inflammation may have a long-term impact on the offspring's HPA axis through dysregulation of maternal, placental and fetal corticosteroid metabolism, and children born of obese mothers have increased risk of diabetes and cardiovascular disease. The long-term effects of maternal obesity on offspring neurodevelopment are, however, undetermined and could depend on the specific effects on placental and fetal cortisol metabolism. This systematic review evaluates how maternal obesity affects placental cortisol metabolism and the offspring's HPA axis. Pubmed, Embase and Scopus were searched for original studies on maternal BMI, obesity, and cortisol metabolism and transfer. Fifteen studies were included after the screening of 4556 identified records. Studies were small with heterogeneous exposures and outcomes. Two studies found that maternal obesity reduced placental HSD11β2 activity. In one study, umbilical cord blood cortisol levels were affected by maternal BMI. In three studies, an altered cortisol response was consistently seen among offspring in childhood (n = 2) or adulthood (n = 1). Maternal BMI was not associated with placental HSD11β1 or HSD11β2 mRNA expression, or placental HSD11β2 methylation. In conclusion, high maternal BMI is associated with reduced placental HSD11β2 activity and a dampened cortisol level among offspring, but the data is sparse. Further investigations are needed to clarify whether the HPA axis is affected by prenatal factors including maternal obesity and investigate if adverse effects can be ameliorated by optimising the intrauterine environment.

ABCB1 expression is increased in human first trimester placenta from pregnant women classified as overweight or obese

Obesity has become a global health challenge also affecting reproductive health. In pregnant women, obesity increases the risk of complications such as preterm birth, macrosomia, gestational diabetes, and preeclampsia. Moreover, obesity is associated with long-term adverse effects for the offspring, including increased risk of cardiovascular and metabolic diseases and neurodevelopmental difficulties. The underlying mechanisms are far from understood, but placental function is essential for pregnancy outcome. Transporter proteins P-glycoprotein (P-gp) and Breast Cancer Resistance Protein (BCRP) are important for trans-placental transport of endogenous substances like lipids and cortisol, a key hormone in tissue maturation. They also hold a protective function protecting the fetus from xenobiotics (e.g. pharmaceuticals). Animal studies suggest that maternal nutritional status can affect expression of placental transporters, but little is known about the effect on the human placenta, especially in early pregnancy. Here, we investigated if overweight and obesity in pregnant women altered mRNA expression of ABCB1 encoding P-gp or ABCG2 encoding BCRP in first trimester human placenta. With informed consent, 75 first trimester placental samples were obtained from women voluntarily seeking surgical abortion (< gestational week 12) (approval no.: 20060063). Villous samples (average gestational age 9.35 weeks) were used for qPCR analysis. For a subset (n = 38), additional villi were snap-frozen for protein analysis. Maternal BMI was defined at the time of termination of pregnancy. Compared to women with BMI 18.5-24.9 kg/m² (n = 34), ABCB1 mRNA expression was significantly increased in placenta samples from women classified as overweight (BMI 25-29.9 kg/m², n = 18) (p = 0.040) and women classified as obese (BMI ≥ 30 kg/m², n = 23) (p = 0.003). Albeit P-gp expression did not show statistically significant difference between groups, the effect of increasing BMI was the same in male and female pregnancies. To investigate if the P-gp increase was compensated, we determined the expression of ABCG2 which was unaffected by maternal obesity (p = 0.291). Maternal BMI affects ABCB1 but not ABCG2 mRNA expression in first trimester human placenta. Further studies of early placental function are needed to understand how the expression of placental transport proteins is regulated by maternal factors such as nutritional status and determine the potential consequences for placental-fetal interaction.

Regulation of Placental Efflux Transporters during Pregnancy Complications

The placenta is essential for regulating the exchange of solutes between the maternal and fetal circulations. As a result, the placenta offers support and protection to the developing fetus by delivering crucial nutrients and removing waste and xenobiotics. ATP-binding cassette transporters, including multidrug resistance protein 1, multidrug resistance-associated proteins, and breast cancer resistance protein, remove chemicals through active efflux and are considered the primary transporters within the placental barrier. Altered transporter expression at the barrier could result in fetal exposure to chemicals and/or accumulation of xenobiotics within trophoblasts. Emerging data demonstrate that expression of these transporters is changed in women with pregnancy complications, suggesting potentially compromised integrity of placental barrier function. The purpose of this review is to summarize the regulation of placental efflux transporters during medical complications of pregnancy, including 1) placental inflammation/infection and chorioamnionitis, 2) hypertensive disorders of pregnancy, 3) metabolic disorders including gestational diabetes and obesity, and 4) fetal growth restriction/altered fetal size for gestational age. For each disorder, we review the basic pathophysiology and consider impacts on the expression and function of placental efflux transporters. Mechanisms of transporter dysregulation and implications for fetal drug and toxicant exposure are discussed. Understanding how transporters are up- or downregulated during pathology is important in assessing possible exposures of the fetus to potentially harmful chemicals in the environment as well as the disposition of novel therapeutics intended to treat placental and fetal diseases. SIGNIFICANCE STATEMENT: Diseases of pregnancy are associated with reduced expression of placental barrier transporters that may impact fetal pharmacotherapy and exposure to dietary and environmental toxicants.

Transporter Regulation in Critical Protective Barriers: Focus on Brain and Placenta

Drug transporters play an important role in the maintenance of chemical balance and homeostasis in different tissues. In addition to their physiological functions, they are crucial for the absorption, distribution, and elimination of many clinically important drugs, thereby impacting therapeutic efficacy and toxicity. Increasing evidence has demonstrated that infectious, metabolic, inflammatory, and neurodegenerative diseases alter the expression and function of drug transporters. However, the current knowledge on transporter regulation in critical protective barriers, such as the brain and placenta, is still limited and requires more research. For instance, while many studies have examined P-glycoprotein, it is evident that research on the regulation of highly expressed transporters in the blood–brain barrier and blood–placental barrier are lacking. The aim of this review is to summarize the currently available literature in order to better understand transporter regulation in these critical barriers.

Polypharmacy in polymorbid pregnancies and the risk of congenital malformations-A systematic review

With an increased prevalence of concurrent morbidities during pregnancy, polypharmacy has become increasingly common in pregnant women. The risks associated with polypharmacy may exceed those of individual medication because of drug-drug interactions. This systematic review aims to evaluate the risk of congenital malformations in polymorbid pregnancies exposed to first-trimester polypharmacy. PubMed, Embase and Scopus were searched to identify original human studies with first- trimester polypharmacy due to polymorbidity as the exposure and congenital malformations as the outcome. After screening of 4034 identified records, seven studies fulfilled the inclusion criteria. Four of the seven studies reported an increased risk of congenital malformations compared with unexposed or monotherapy, odds ratios ranging from 1.1 to >10.0. Particularly, short-term anti-infective treatment combined with other drugs and P-glycoprotein substrates were associated with increased malformation risks. In conclusion, knowledge is limited on risks associated with first-trimester polypharmacy due to polymorbidity with the underlying evidence of low quantity and quality. Therefore, an increased focus on pharmacovigilance to enable safe drug use in early pregnancy is needed. Large-scale register-based studies and better knowledge of placental biology are needed to support the clinical management of polymorbid pregnancies that require polypharmacy.

Mechanistic Modeling of Placental Drug Transfer in Humans: How Do Differences in Maternal/Fetal Fraction of Unbound Drug and Placental Influx/Efflux Transfer Rates Affect Fetal Pharmacokinetics?

Background: While physiologically based pharmacokinetic (PBPK) models generally predict pharmacokinetics in pregnant women successfully, the confidence in predicting fetal pharmacokinetics is limited because many parameters affecting placental drug transfer have not been mechanistically accounted for. Objectives: The objectives of this study were to implement different maternal and fetal unbound drug fractions in a PBPK framework; to predict fetal pharmacokinetics of eight drugs in the third trimester; and to quantitatively investigate how alterations in various model parameters affect predicted fetal pharmacokinetics. Methods: The ordinary differential equations of previously developed pregnancy PBPK models for eight drugs (acyclovir, cefuroxime, diazepam, dolutegravir, emtricitabine, metronidazole, ondansetron, and raltegravir) were amended to account for different unbound drug fractions in mother and fetus. Local sensitivity analyses were conducted for various parameters relevant to placental drug transfer, including influx/efflux transfer clearances across the apical and basolateral membrane of the trophoblasts. Results: For the highly-protein bound drugs diazepam, dolutegravir and ondansetron, the lower fraction unbound in the fetus vs. mother affected predicted pharmacokinetics in the umbilical vein by ≥10%. Metronidazole displayed blood flow-limited distribution across the placenta. For all drugs, umbilical vein concentrations were highly sensitive to changes in the apical influx/efflux transfer clearance ratio. Additionally, transfer clearance across the basolateral membrane was a critical parameter for cefuroxime and ondansetron. Conclusion: In healthy pregnancies, differential protein binding characteristics in mother and fetus give rise to minor differences in maternal-fetal drug exposure. Further studies are needed to differentiate passive and active transfer processes across the apical and basolateral trophoblast membrane.

Effects of Maternal Obesity On Placental Phenotype

The incidence of obesity is rising rapidly worldwide with the consequence that more women are entering pregnancy overweight or obese. This leads to an increased incidence of clinical complications during pregnancy and of poor obstetric outcomes. The offspring of obese pregnancies are often macrosomic at birth although there is also a subset of the progeny that are growth-restricted at term. Maternal obesity during pregnancy is also associated with cardiovascular, metabolic and endocrine dysfunction in the offspring later in life. As the interface between the mother and fetus, the placenta has a central role in programming intrauterine development and is known to adapt its phenotype in response to environmental conditions such as maternal undernutrition and hypoxia. However, less is known about placental function in the abnormal metabolic and endocrine environment associated with maternal obesity during pregnancy. This review discusses the placental consequences of maternal obesity induced either naturally or experimentally by increasing maternal nutritional intake and/or changing the dietary composition. It takes a comparative, multi-species approach and focusses on placental size, morphology, nutrient transport, metabolism and endocrine function during the later stages of obese pregnancy. It also examines the interventions that have been made during pregnancy in an attempt to alleviate the more adverse impacts of maternal obesity on placental phenotype. The review highlights the potential role of adaptations in placental phenotype as a contributory factor to the pregnancy complications and changes in fetal growth and development that are associated with maternal obesity.

Effects of Maternal Obesity and Gestational Diabetes Mellitus on the Placenta: Current Knowledge and Targets for Therapeutic Interventions

Obesity and gestational diabetes mellitus (GDM) are becoming more common among pregnant women worldwide and are individually associated with a number of placenta-mediated obstetric complications, including preeclampsia, macrosomia, intrauterine growth restriction and stillbirth. The placenta serves several functions throughout pregnancy and is the main exchange site for the transfer of nutrients and gas from mother to fetus. In pregnancies complicated by maternal obesity or GDM, the placenta is exposed to environmental changes, such as increased inflammation and oxidative stress, dyslipidemia, and altered hormone levels. These changes can affect placental development and function and lead to abnormal fetal growth and development as well as metabolic and cardiovascular abnormalities in the offspring. This review aims to summarize current knowledge on the effects of obesity and GDM on placental development and function. Understanding these processes is key in developing therapeutic interventions with the goal of mitigating these effects and preventing future cardiovascular and metabolic pathology in subsequent generations.

Inter-individual variations and modulators of MDR1 transport activity in human placenta

INTRODUCTION

ATP binding cassette (ABC) membrane transporter multidrug resistance 1 (MDR1) is one of the most important efflux transporters in the human placenta protecting the fetus from exposure to xenobiotic toxicity. Recent studies have focused on placental MDR1 expression, but few studies have analyzed placental MDR1 transport activity. The purpose of this study was to investigate placental MDR1 transport activity using a relatively large sample size of human placentas. Furthermore, the effect of ABCB1 gene polymorphisms were investigated along with physiological factors including maternal age, times of pregnancy, BMI, delivery mode or pregnancy complications on placental MDR1 transport activity.

METHODS

A total of 252 human placentas were obtained after delivery. MDR1 transport activity was detected by N-methyl quinidine uptake in placental microvillus membrane vesicles (MVMVs). Nine common single nucleotide polymorphisms (SNPs) in ABCB1 genes were determined by Snapshot. The association between ABCB1 gene polymorphisms, maternal age, times of pregnancy, BMI, delivery mode or pregnancy complications, and transporter activity was investigated.

RESULTS

Inter-individual variations of MDR1 transport activity were observed among 252 subjects. The per unit protein activity was ranged from 0.05 to 0.15/mg. Nine SNPs in ABCB1 gene didn't exhibit significant association with transporter activity of MDR1. Likewise, neither age, times of pregnancy, delivery mode nor pregnancy complications showed any significant effect of placental MDR1 transport activity. But placental MDR1 transport activity in obese pregnant women was lower than those in non-obese pregnant women.

CONCLUSION

Inter-individual variations of MDR1 transport activity existed in human placentas. This may contribute to variations in drug exposure to the fetus affecting clinical outcomes. Maternal age, times of pregnancy, delivery mode nor pregnancy complications included in this study maybe not significantly impact placental MDR1 transport activity, but maternal obese could inhibit placental MDR1 activity.

Prediction of Maternal and Fetal Pharmacokinetics of Dolutegravir and Raltegravir Using Physiologically Based Pharmacokinetic Modeling

BACKGROUND

Predicting drug pharmacokinetics in pregnant women including placental drug transfer remains challenging. This study aimed to develop and evaluate maternal-fetal physiologically based pharmacokinetic models for two antiretroviral drugs, dolutegravir and raltegravir.

Placental transporter-mediated drug interactions and offspring congenital anomalies

Aims

P‐glycoprotein (P‐gp) and breast cancer resistance protein (BCRP) are efflux transporters expressed in the placenta, limiting their substrates from reaching the foetus. Our aim was to investigate if concomitant prenatal exposure to several substrates or inhibitors of these transporters increases the risk of congenital anomalies.

Methods

The national Drugs and Pregnancy database, years 1996–2014, was utilized in this population‐based birth cohort study. In the database, the Medical Birth Register, the Register on Induced Abortions, the Malformation register and the Register on Reimbursed Drug Purchases have been linked. The University of Washington Metabolism and Transport Drug Interaction Database was used to identify substrates and inhibitors of P‐gp and BCRP. We included singleton pregnancies ending in birth or elective termination of pregnancy due to foetal anomaly. Known teratogens were excluded. We identified women exposed 1 month before pregnancy or during the first trimester to P‐gp/BCRP polytherapy (n = 21 186); P‐gp/breast cancer resistance protein monotherapy (n = 97 906); non‐P‐gp/BCRP polytherapy (n = 78 636); and unexposed (n = 728 870). We investigated the association between the exposure groups and major congenital anomalies using logistic regression adjusting for several confounders.

Results

The prevalence of congenital anomalies was higher in the P‐gp/BCRP polytherapy group (5.5%) compared to the P‐gp/BCRP monotherapy (4.7%, OR 1.13; 95% CI 1.05–1.21), the non‐P‐gp/BCRP polytherapy (4.9%, OR 1.14; 95% CI 1.06–1.22), and to the unexposed groups (4.2%, OR 1.23; 95% CI 1.15–1.31).

Conclusion

The results suggest a role of placental transporter‐mediated drug interactions in teratogenesis.

Investigation of Lipid Metabolism by a New Structured Lipid with Medium- and Long-Chain Triacylglycerols from Cinnamomum camphora Seed Oil in Healthy C57BL/6J Mice

In the present study, a new structured lipid with medium- and long-chain triacylglycerols (MLCTs) was synthesized from camellia oil (CO) and Cinnamomum camphora seed oil (CCSO) by enzymatic interesterification. Meanwhile, the antiobesity effects of structured lipid were investigated through observing the changes of enzymes related to lipid mobilization in healthy C57BL/6J mice. Results showed that after synthesis, the major triacylgeride (TAG) species of intesterificated product changed to LaCC/CLaC (12.6 ± 0.46%), LaCO/LCL (21.7 ± 0.76%), CCO/LaCL (14.2 ± 0.55%), COO/OCO (10.8 ± 0.43%), and OOO (18.6 ± 0.64%). Through second-stage molecular distillation, the purity of interesterified product (MLCT) achieved 95.6%. Later, male C57BL/6J mice were applied to study whether the new structured lipid with MLCT has the efficacy of preventing the formation of obesity or not. After feeding with different diets for 6 weeks, MLCTs could reduce body weight and fat deposition in adipose tissue, lower plasma triacylglycerols (TG) (0.89 ± 0.16 mmol/L), plasma total cholesterol (TC) (4.03 ± 0.08 mmol/L), and hepatic lipids (382 ± 34.2 mg/mice) by 28.8%, 16.0%, and 30.5%, respectively, when compared to the control 2 group. This was also accompanied by increasing fecal lipids (113%) and the level of enzymes including cyclic adenosine monophosphate (cAMP), protein kinase A (PKA), hormone-sensitive lipase (HSL), and adipose triglyceride lipase (ATGL) related to lipid mobilization in MLCT group. From the results, it can be concluded that MLCT reduced body fat deposition probably by modulating enzymes related to lipid mobilization in C57BL/6J mice.

HDAC2 was involved in placental P-glycoprotein regulation both in vitro and vivo

INTRODUCTION

Placental P-glycoprotein (P-gp) plays a significant role in regulating drugs' transplacental transfer rates. Investigations on placental P-gp regulation could provide more therapeutic targets for individualized and safe pharmacotherapy during pregnancy. Currently, the epigenetic regulation of placental P-gp is rare. Our previous study has demonstrated that HDACs inhibition could up-regulate placental P-gp and HDAC1/2/3 might be involved in this process. The present study was carried out to further explore whether HDAC1/2/3 were indeed involved in the regulation of placental P-gp or not and screen out the subtype engaged in this process.

METHODS

BeWo and JAR cells were transfected with HDAC1/2/3 specific siRNA. After 48 h of transfection, cells were harvested for real-time quantitative PCR (qRT-PCR), Western blot, immunofluorescence and fluorescent dye efflux assay to evaluate P-gp expression, localization, and efflux activity, respectively. Hdac2 siRNA was intraperitoneally injected to pregnant mice every 48 h from E7.5 to E15.5 and digoxin was administered by gavages 1 h prior to euthanasia at E16.5. Placental Hdac1/2/3 and P-gp expression were determined by qRT-PCR and Western blot. Maternal plasma and fetal-unit digoxin concentrations were detected by enzyme-multiplied immunoassay.

RESULTS

In vitro, HDAC2 inhibition could significantly elevate P-gp expression and reduce intracellular accumulation of P-gp substrates (DiOC₂ (3) and Rh 123) both in BeWo and JAR, while knockdown of HDAC1/3 had no influence on P-gp expression and its efflux activity. Additionally, in vivo, Hdac2 silencing in pregnant mice also elevated placental P-gp expression and decreased digoxin transplacental transfer rate.

CONCLUSION

HDAC2 inhibition could result in induction of placental P-gp expression and functionality both in vitro and in vivo.

The effect of 17α-ethynylestradiol induced intrahepatic cholestasis of pregnancy on placental P-glycoprotein in mice: Implications in the individualized transplacental digoxin treatment for fetal heart failure

INTRODUCTION

Placental P-glycoprotein (P-gp) plays a significant role in controlling transplacental digoxin transfer rate. Investigations on P-gp regulation in placenta of women with different pregnant pathological states are of great significance to individualized transplacental digoxin treatment for fetal heart failure (FHF). This study aimed to explore the effect of 17α-ethynylestradiol induced intrahepatic cholestasis of pregnancy (ICP) on placental P-gp in mice.

METHODS

ICP model in mice was induced by subcutaneous injection of 17α-ethynylestradiol dissolved in propylene glycol once daily from E12.5 to E16.5. Maternal plasma ALT, AST, TB, DBIL, γ-GT, LDH, ALP and TBA concentrations were measured. HE staining was applied for observation of maternal liver cells degeneration, necrosis and intrahepatic cholestasis. Placental Abcb1a/Abcb1b/HIF-1α mRNA and P-gp/HIF-1α protein expression were determined by real-time quantitative PCR and western-blot. Maternal plasma and fetal-unit digoxin concentrations were detected by a commercial kit assay.

RESULTS

The ICP group showed higher levels of maternal plasma ALT, AST, TB, DBIL, γ-GT, LDH, ALP and TBA concentrations, reduction in fetal survival rates, lower placental and fetal weights, and typical liver cells degeneration, necrosis and intrahepatic cholestasis. The placental Abcb1a mRNA and P-gp expression of ICP group were significantly elevated, while transplacental digoxin transfer rates were significantly decreased. Both placental HIF-1α mRNA and protein expression was significantly elevated in the ICP group, and there was a positive correlation between Abcb1a mRNA and HIF-1α mRNA.

CONCLUSIONS

17α-ethynylestradiol induced ICP could up-regulate placental P-gp expression and reduce transplacental digoxin transfer rate in mice, which might be partly associated with higher expression of HIF-1α.

The Programming Power of the Placenta

Size at birth is a critical determinant of life expectancy, and is dependent primarily on the placental supply of nutrients. However, the placenta is not just a passive organ for the materno-fetal transfer of nutrients and oxygen. Studies show that the placenta can adapt morphologically and functionally to optimize substrate supply, and thus fetal growth, under adverse intrauterine conditions. These adaptations help meet the fetal drive for growth, and their effectiveness will determine the amount and relative proportions of specific metabolic substrates supplied to the fetus at different stages of development. This flow of nutrients will ultimately program physiological systems at the gene, cell, tissue, organ, and system levels, and inadequacies can cause permanent structural and functional changes that lead to overt disease, particularly with increasing age. This review examines the environmental regulation of the placental phenotype with particular emphasis on the impact of maternal nutritional challenges and oxygen scarcity in mice, rats and guinea pigs. It also focuses on the effects of such conditions on fetal growth and the developmental programming of disease postnatally. A challenge for future research is to link placental structure and function with clinical phenotypes in the offspring.