Changes in Expression and Function of Placental and Intestinal P-gp and BCRP Transporters during Pregnancy

ABC transporters are ubiquitous in the human body and are responsible for the efflux of drugs. They are present in the placenta, intestine, liver and kidney, which are the major organs that can affect the pharmacokinetic and pharmacologic properties of drugs. P-gp and BCRP transporters are the best-characterized transporters in the ABC superfamily, and they have a pivotal role in the barrier tissues due to their efflux mechanism. Moreover, during pregnancy, drug efflux is even more important because of the developing fetus. Recent studies have shown that placental and intestinal ABC transporters have great importance in drug absorption and distribution. Placental and intestinal P-gp and BCRP show gestational-age-dependent expression changes, which determine the drug concentration both in the mother and the fetus during pregnancy. They may have an impact on the efficacy of antibiotic, antiviral, antihistamine, antiemetic and oral antidiabetic therapies. In this review, we would like to provide an overview of the pharmacokinetically relevant expression alterations of placental and intestinal ABC transporters during pregnancy.

Primary, Secondary, and Tertiary Prevention of Congenital Cytomegalovirus Infection

Cytomegalovirus infection is the most common congenital infection, affecting about 1% of births worldwide. Several primary, secondary, and tertiary prevention strategies are already available during the prenatal period to help mitigate the immediate and long-term consequences of this infection. In this review, we aim to present and assess the efficacy of these strategies, including educating pregnant women and women of childbearing age on their knowledge of hygiene measures, development of vaccines, screening for cytomegalovirus infection during pregnancy (systematic versus targeted), prenatal diagnosis and prognostic assessments, and preventive and curative treatments in utero.

Induction of human trophoblast stem-like cells from primed pluripotent stem cells

Treatment with bone morphogenetic protein 4 (BMP4) in human primed pluripotent stem cells (PSCs) for generating trophoblast lineage cells has sparked debate that the resulting cells are closer to amnion lineage cells rather than trophoblast. This study reports that trophoblast stem-like cells (TSLCs) can be generated from human primed PSCs by a short-term treatment of BMP4 without amnion lineage marker expression. In addition, we describe that TSLCs are self-renewing in long-term culture and bipotent as they can differentiate into functional extravillous trophoblasts and syncytiotrophoblasts. We propose an alternative method to generate an available model for studying human placental development from human primed PSCs.

The placenta is a transient but important multifunctional organ crucial for healthy pregnancy for both mother and fetus. Nevertheless, limited access to human placenta samples and the paucity of a proper in vitro model system have hampered our understanding of the mechanisms underlying early human placental development and placenta-associated pregnancy complications. To overcome these constraints, we established a simple procedure with a short-term treatment of bone morphogenetic protein 4 (BMP4) in trophoblast stem cell culture medium (TSCM) to convert human primed pluripotent stem cells (PSCs) to trophoblast stem-like cells (TSLCs). These TSLCs show not only morphology and global gene expression profiles comparable to bona fide human trophoblast stem cells (TSCs) but also long-term self-renewal capacity with bipotency that allows the cells to differentiate into functional extravillous trophoblasts (EVT) and syncytiotrophoblasts (ST). These indicate that TSLCs are equivalent to genuine human TSCs. Our data suggest a straightforward approach to make human TSCs directly from preexisting primed PSCs and provide a valuable opportunity to study human placenta development and pathology from patients with placenta-related diseases.

Mild hearing loss in C57BL6/J mice after exposure to antiretroviral compounds during gestation and nursing

OBJECTIVE

There is evidence of ototoxicity from antiretrovirals (ARVs), and ARV therapy in pregnant/nursing mothers can expose offspring to these compounds. The current work modelled whether exposure to ARVs in utero and during nursing altered the functioning of the auditory system in offspring mice.

DESIGN

The females of seven breeding pairs of C57BL6/J mice were given daily doses of ARVs lamivudine and tenofovir disoproxil fumarate by oral gavage during gestation and nursing. Three breeder females were given equivalent volumes of water as controls. At wean age (3 weeks after birth), the offspring mice were tested with auditory brainstem responses (ABRs). At the conclusion of the experiment, the offspring mice's cochleae were examined for hair cell counts.

STUDY SAMPLE

Ten breeder female C57BL6/J mice and 69 offspring mice.

RESULTS

The offspring mice exposed to ARVs during development showed higher ABR thresholds than the control offspring. No differences were found in supra-threshold ABRs. There was no evidence of missing hair cells.

CONCLUSIONS

Hearing impairment may be a possible consequence of exposure to ARVs during gestation and development. Because the threshold differences were not large, if they are occurring in humans, it is unlikely they would be identified in any hearing screening tests.

COVID-19 during Pregnancy and Postpartum

Coronavirus Disease 2019 (COVID-19) triggered by Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) infection has been declared a pandemic by the World Health Organization (WHO) on March 11, 2020. Oxidative stress and its related metabolic syndromes are potential risk factors in the susceptibility to, and severity of COVID-19. In concert with the earliest reports of COVID-19, obstetricians started to diagnose and treat SARS-CoV-2 infections during pregnancy ("COVID-19-Pregnancy"). High metabolic demand to sustain normal fetal development increases the burden of oxidative stress in pregnancy. Intracellular redox changes intertwined with acute phase responses at the maternal-fetal interface could amplify during pregnancy. Interestingly, mother-to-fetus transmission of SARS-CoV-2 has not been detected in most of the COVID-19-Pregnancy cases. This relative absence of vertical transmission may be related to the presence of lactoferrin in the placenta, amniotic fluid, and lacteal secretions. However, the cytokine-storm induced during COVID-19-Pregnancy may cause severe inflammatory damage to the fetus, and if uncontrolled, may later result in autism spectrum-like disorders and brain development abnormalities in neonates. Considering this serious health threat to child growth and development, the prevention of COVID-19 during pregnancy should be considered a high priority. This review summarizes the intricate virulence factors of COVID-19 and elucidate its pathobiological spectrum during pregnancy and postpartum periods with a focus on the putative and complex roles of endogenous and exogenous lactoferrin in conferring immunological advantage to the host.

Contributions of Drug Transporters to Blood-Placental Barrier

The placenta is the only organ linking two different individuals, mother and fetus, termed as blood-placental barrier. The functions of the blood-placental barrier are to regulate material transfer between the maternal and fetal circulation. The main functional units are the chorionic villi within which fetal blood is separated by only three or four cell layers (placental membrane) from maternal blood in the surrounding intervillous space. A series of drug transporters such as P-glycoprotein (P-GP), breast cancer resistance protein (BCRP), multidrug resistance-associated proteins (MRP1, MRP2, MRP3, MRP4, and MRP5), organic anion-transporting polypeptides (OATP4A1, OATP1A2, OATP1B3, and OATP3A1), organic anion transporter 4 (OAT4), organic cation transporter 3 (OCT3), organic cation/carnitine transporters (OCTN1 and OCTN2), multidrug and toxin extrusion 1 (MATE1), and equilibrative nucleoside transporters (ENT1 and ENT2) have been demonstrated on the apical membrane of syncytiotrophoblast, some of which also expressed on the basolateral membrane of syncytiotrophoblast or fetal capillary endothelium. These transporters are involved in transport of most drugs in the placenta, in turn, affecting drug distribution in fetus. Moreover, expressions of these transporters in the placenta often vary along with the gestational ages and are also affected by pathophysiological factor. This chapter will mainly illustrate function and expression of these transporters in placentas, their contribution to drug distribution in fetus, and their clinical significance.

Quantification of ENT1 and ENT2 Proteins at the Placental Barrier and Contribution of These Transporters to Ribavirin Uptake

The aims of this study are to quantify the protein levels of nucleoside transporters in placental microvillous membranes (MVMs) and to clarify the contributions of these transporters to ribavirin uptake at the placental barrier. Placental MVMs of human and rat expressed equilibrative nucleoside transporter (ENT) 1 protein, whereas the expression of ENT2 protein was obscure. Maternal-to-fetal transfer of [³H]ribavirin in rats was much higher than that of [¹⁴C]sucrose. The uptake of [³H]ribavirin by rat placental trophoblast TR-TBT 18 d-1 cells, which functionally express both ENT1 and ENT2 proteins, was saturable, and was significantly inhibited by 0.1 μM nitrobenzylthioinosine, which selectively abolishes ENT1-mediated uptake. Dipyridamole at 10 μM is capable of inhibiting ENT2 as well as ENT1, but a degree of inhibition by 10 μM dipyridamole on [³H]ribavirin uptake was not much different from that by 0.1 μM nitrobenzylthioinosine (ENT1-specific inhibitor). Therefore, ENT2 may contribute little to [³H]ribavirin uptake by these cells. Rat ENT1 cRNA-injected oocytes showed increased [³H]ribavirin uptake compared with water-injected oocytes, while rat ENT2 cRNA-injected oocytes did not. In conclusion, ENT1 protein expressed in placental MVMs appears to play a predominant role in the uptake of ribavirin.

[Management of pregnant women with first episode of genital herpes. Guidelines for clinical practice from the French college of gynecologists and obstetricians (CNGOF)]

OBJECTIVE

To provide guidelines for the management of first episode genital herpes during pregnancy and in the immediate postpartum period.

METHODS

MedLine and Cochrane Library databases search and review of the main foreign guidelines.

RESULTS

In case of first episode genital herpes during pregnancy, antiviral treatment with acyclovir (200mg 5 times daily) or valacyclovir (1000mg twice daily) for 5 to 10 days is recommended (grade C). The patient should be tested for HIV if not previously done (grade B). Daily suppressive antiviral treatment with acyclovir (400mg 3 times daily) or valacyclovir (500mg twice daily) is recommended from 36 weeks for women who have had a first episode genital herpes during pregnancy (grade B). A cesarean section should be performed in case of suspicion of first episode genital herpes at the onset of labor (grade B) or premature rupture of the membranes at term (professional consensus), or in case of first episode genital herpes less than 6 weeks before delivery (professional consensus). In the event of first episode genital herpes highlighted in the postpartum period, the neonatologist should be informed (professional consensus). The patient may be treated according the scheme described above.

CONCLUSION

A cesarean section should be performed in case of first episode genital herpes less than 6 weeks before delivery.

Role of nucleoside transporters in transplacental pharmacokinetics of nucleoside reverse transcriptase inhibitors zidovudine and emtricitabine

INTRODUCTION

Zidovudine (AZT) and emtricitabine (FTC) are effective and well tolerated antiretroviral drugs, routinely used in the prevention of perinatal HIV transmission. However, precise mechanism(s) involved in their transfer from mother to fetus are not fully elucidated. Since both drugs are nucleoside analogues, we hypothesized that the mechanisms of their transplacental passage might include equilibrative nucleoside transporters, ENT1 and/or ENT2.

METHODS

To address this issue, we performed in vitro accumulation assays in the BeWo placental trophoblast cell line, ex vivo uptake studies in fresh villous fragments isolated from human placenta and in situ dually perfused rat term placenta experiments.

RESULTS

Applying this complex array of methods, we did not prove that ENTs play a significant role in transfer of AZT or FTC across the placenta.

DISCUSSION

We conclude that the transplacental passage of AZT and FTC is independent of ENTs. Disposition of either compound into the fetal circulation should thus not be affected by ENT-mediated drug-drug interactions or placental expression of the transporters.

The Role of PXR Genotype and Transporter Expression in the Placental Transport of Lopinavir in Mice

Lopinavir (LPV), an antiretroviral protease inhibitor frequently prescribed in HIV-positive pregnancies, is a substrate of Abcb1 and Abcc2. As differences in placental expression of these transporters were seen in Pregnane X Receptor (PXR) −/− mice, we examined the impact of placental transporter expression and fetal PXR genotype on the fetal accumulation of LPV. PXR +/− dams bearing PXR +/+, PXR +/−, and PXR −/− fetuses were generated by mating PXR +/− female mice with PXR +/− males. On gestational day 17, dams were administered 10 mg/kg LPV (i.v.) and sacrificed 30 min post injection. Concentrations of LPV in maternal plasma and fetal tissue were measured by LC-MS/MS, and transporter expression was determined by quantitative RT-PCR. As compared to the PXR +/+ fetal units, placental expression of Abcb1a, Abcc2, and Abcg2 mRNA were two- to three-fold higher in PXR −/− fetuses (p < 0.05). Two-fold higher fetal:maternal LPV concentration ratios were also seen in the PXR +/+ as compared to the PXR −/− fetuses (p < 0.05), and this significantly correlated to the placental expression of Abcb1a (r = 0.495; p < 0.005). Individual differences in the expression of placental transporters due to genetic or environmental factors can impact fetal exposure to their substrates.

SOMANZ guidelines for the investigation and management sepsis in pregnancy

SOMANZ (Society of Obstetric Medicine Australia and New Zealand) has written a guideline to provide evidence-based guidance for the investigation and care of women with sepsis in pregnancy or the postpartum period. The guideline is evidence-based and incorporates recent changes in the definition of sepsis. The etiology, investigation and treatment of bacterial, viral and non-infective causes of sepsis are discussed. Obstetric considerations relevant to anaesthetic and intensive care treatment in sepsis are also addressed. A multi-disciplinary group of clinicians with experience in all aspects of the care of pregnant women have contributed to the development of the guidelines. This is an executive summary of the guidelines.

Tolerance of the newborn to antiretroviral drug exposure in utero

INTRODUCTION

The prevention of mother-to-child HIV-1 transmission by antiretroviral drug treatment is remarkably effective. The risk of transmission to the child is now almost zero for women optimally treated during pregnancy. The rapid expansion of this prophylactic treatment has led the World Health Organization to aspire to the virtual elimination of mother-to-child transmission and pediatric AIDS over the next few years. In 2014, more than 900,000 women worldwide were treated with antiretroviral drugs during pregnancy. The issue of fetal and neonatal antiretroviral drug tolerance is therefore extremely important.

AREAS COVERED

This review focuses on the possible impact of in utero exposure to antiretroviral drug on newborn health. To restrict analysis to this period is justified by the specificities of transplacental drug exposure and fetal vulnerability. Relevant data are available from trials and observational cohorts. The significance of various bio-markers detectable at birth is still unresolved, but merits a careful evaluation. Long-term assessment is associated with various logistical difficulties.

EXPERT OPINION

The health of 'exposed but not infected' children poses no major problem in the immense majority of cases, but a series of biological, clinical and imaging-based warning signs have emerged indicating the need for careful attention to be paid to this issue. Some effects that are straightforward to manage in industrialized countries may have more severe consequences in countries in which access to effective healthcare is limited. Nucleoside/nucleotide analogs are potentially genotoxic to mitochondrial and nuclear DNA, and the principal question to be addressed concerns their potential long-term effects.

Influenza and its treatment during pregnancy: A review

The influenza viral infection has dramatic effects during pregnancy on the mother and the fetus. We present a review article on the prevention and treatment recommendations of influenza infection in pregnant women, and the effects of antiviral medications on maternal-fetal outcomes. This viral infection not only leads to miscarriages, preterm deliveries and a high maternal mortality rate, but it also poses negative risks to the fetus including small-for-gestational age infants, and admissions to neonatal intensive care units. Vaccination is the most effective strategy for preventing influenza infection during pregnancy whereby can protect both maternal and fetal immunities. The safety profiles of antiviral drugs during pregnancy are limited. Available risk-benefit evidence has indicated that pregnant women with suspected or confirmed influenza should receive prompt antiviral therapy where these medications reduce the risk of complications among pregnant women, and attenuate the teratogenic effects of the influenza infection. Post-exposure prophylaxis is not recommended for most pregnant women, but it may be prescribed in pandemic settings, particularly to non-vaccinated women. Although some ex vivo models for pharmacokinetic studies have revealed that the transplacental transfer of oseltamivir to fetal circuits may occur, there is no evidence of adverse fetal outcomes as a result of most in utero exposures to neuraminidase inhibitors. Due to the large number of confounding variables, large, population-based studies are needed to assess the association between in utero oseltamivir exposure and fetal outcome.

Genital herpes and its treatment in relation to preterm delivery

To examine the risks of genital herpes and antiherpes treatment during pregnancy in relation to preterm delivery (PTD), we conducted a multicenter, member-based cohort study within 4 Kaiser Permanente regions: northern and southern California, Colorado, and Georgia. The study included 662,913 mother-newborn pairs from 1997 to 2010. Pregnant women were classified into 3 groups based on genital herpes diagnosis and treatment: genital herpes without treatment, genital herpes with antiherpes treatment, and no herpes diagnosis or treatment (unexposed controls). After controlling for potential confounders, we found that compared with being unexposed, having untreated genital herpes during first or second trimester was associated with more than double the risk of PTD (odds ratio (OR) = 2.23, 95% confidence interval (CI): 1.80, 2.76). The association was stronger for PTD due to premature rupture of membrane (OR = 3.57, 95% CI: 2.53, 5.06) and for early PTD (≤35 weeks gestation) (OR = 2.87, 95% CI: 2.22, 3.71). In contrast, undergoing antiherpes treatment during pregnancy was associated with a lower risk of PTD compared with not being treated, and the PTD risk was similar to that observed in the unexposed controls (OR = 1.11, 95% CI: 0.89, 1.38). The present study revealed increased risk of PTD associated with genital herpes infection if left untreated and a potential benefit of antiherpes medications in mitigating the effect of genital herpes infection on the risk of PTD.

Fetal growth retardation and lack of hypotaurine in ezrin knockout mice

Ezrin is a membrane-associated cytoplasmic protein that serves to link cell-membrane proteins with the actin-based cytoskeleton, and also plays a role in regulation of the functional activities of some transmembrane proteins. It is expressed in placental trophoblasts. We hypothesized that placental ezrin is involved in the supply of nutrients from mother to fetus, thereby influencing fetal growth. The aim of this study was firstly to clarify the effect of ezrin on fetal growth and secondly to determine whether knockout of ezrin is associated with decreased concentrations of serum and placental nutrients. Ezrin knockout mice (Ez^−/−) were confirmed to exhibit fetal growth retardation. Metabolome analysis of fetal serum and placental extract of ezrin knockout mice by means of capillary electrophoresis–time-of-flight mass spectrometry revealed a markedly decreased concentration of hypotaurine, a precursor of taurine. However, placental levels of cysteine and cysteine sulfinic acid (precursors of hypotaurine) and taurine were not affected. Lack of hypotaurine in Ez^−/− mice was confirmed by liquid chromatography with tandem mass spectrometry. Administration of hypotaurine to heterogenous dams significantly decreased the placenta-to-maternal plasma ratio of hypotaurine in wild-type fetuses but only slightly decreased it in ezrin knockout fetuses, indicating that the uptake of hypotaurine from mother to placenta is saturable and that disruption of ezrin impairs the uptake of hypotaurine by placental trophoblasts. These results indicate that ezrin is required for uptake of hypotaurine from maternal serum by placental trophoblasts, and plays an important role in fetal growth.

Influenza in pregnancy

Please cite this paper as: Memoli et al. (2012) Influenza in pregnancy. Influenza and Other Respiratory Viruses 00(00), 000–000.

The 2009 pandemic served as a strong reminder that influenza‐induced disease can have a great impact on certain at‐risk populations and that pregnant women are one such important population. The increased risk of fatal and severe disease in these women was appreciated more than 500 years ago, and during the last century, pregnant women and their newborns have continued to be greatly affected by both seasonal and pandemic influenza. In this review, we briefly discuss the data collected both before and after the 2009 pandemic as it relates to the impact of influenza on pregnant women and their fetuses/newborns, as well as risk variables, clinical features, clues to pathophysiologic mechanisms, and approaches to treatment and prevention.

Prescribing without evidence - pregnancy

Prescribing of medicines during pregnancy is common, and for some groups of women is essential for maintaining maternal and therefore fetal health. Pregnant women and prescribers are rightly concerned, however, about the potential adverse fetal effects of medicines. These may include fetal death or stillbirth, congenital malformations, developmental impairment, neonatal effects or late carcinogenesis. It is therefore essential that the risks and benefits for mother and fetus are considered carefully before prescribing in pregnancy. This is often challenging because of the paucity of information available. To complicate the issue further, drug pharmacokinetics are commonly altered in pregnancy, potentially affecting optimal dosing as well as interpretation of plasma concentration measurements, with specific information on individual drugs seldom available. Most drugs cross the placenta, especially lipophilic drugs and those with low plasma protein binding. Active membrane transporters also have an important role in enhancing or preventing drug transfer, although this is not yet clearly understood. Animal studies have limited applicability to humans because of species-specific effects, and clinical trials in pregnancy are only undertaken in special circumstances. Prescribers therefore need to rely on observational studies of fetal outcomes following drug exposure in human pregnancy. These often involve limited numbers, and data are also subject to confounding and bias, making interpretation difficult. It therefore remains essential that appropriate mechanisms for systematic data collection, including congenital malformation registries, teratology information services, pregnancy registers and linked population registries, are maintained and enhanced to increase the amount and quality of information available.

Darunavir: a critical review of its properties, use and drug interactions

Darunavir is a synthetic nonpeptidic protease inhibitor which has been shown to be extremely potent against wild-type HIV as well as a large panel of PI-resistant clinical isolates and shows a high genetic barrier to the development of antiretroviral resistance. The treatment of HIV/AIDS requires combinations of multiple antiretroviral drugs. In addition, patients frequently need to coadminister other medications for reasons including the prevention or treatment of opportunistic infections, treatment of concomitant illnesses and management of antiretroviral side effects. Drug interactions have been observed between darunavir and other drugs. New and more comprehensive drug interaction studies will be required since the increase in life expectancy of patients often brings new comorbidities and the concomitant use of different drugs. This paper discusses the impact of the use of darunavir in the treatment of HIV-infected patients, its pharmacological and physical-chemical properties, its drug interactions, and challenges that remain in order to ensure safety and compliance of treatment.

Evolutionary-developmental perspectives on immune system interactions among the pregnant woman, placenta, and fetus, and responses to sexually transmitted infectious agents

A balance has evolved over deep time between the various immune systems of the "triad" that is linked together for a short period: the pregnant woman, the fetus, and the placenta. This balance is affected by, and helps to determine, the immune responses to maternal infectious agents that may be transmitted to the fetus/infant transplacentally, intrapartum, or via breast milk. This review identifies newer evolutionary concepts and processes related particularly to the human placenta, innate and adaptive immune systems involved in tolerance, and in responses to sexually transmitted infectious (STI) agents that may be pathogenic to the fetus/infant at different gestational periods and in the first year of life. An evolutionary-developmental (EVO-DEVO) perspective has been applied to the complexities within, and among, the different actors and their beneficial or deleterious outcomes. Such a phylogenetic and ontogenic approach has helped to stimulate several basic questions and suggested possible explanations and novel practical interventions.