Elsevier

Epilepsy Research

Volume 174, August 2021, 106664
Epilepsy Research

Effects of antiseizure medications on placental cells: Focus on heterodimeric placental carriers

https://doi.org/10.1016/j.eplepsyres.2021.106664Get rights and content

Highlights

  • Antiseizure medications (ASMs) can alter the expression of key placental carriers.

  • The effects on carrier expression are drug-specific and concentration-dependent.

  • Heterodimeric transporters are co-regulated in ASM-treated placental cells.

  • Our results suggest a novel mechanism for adverse placental and fetal effect of ASMs.

Abstract

Objective

Appropriate placental nutrient transfer is essential for optimal fetal development. We have previously shown that antiseizure medications (ASMs) can alter the expression of placental carriers for folate and thyroid hormones. Here we extended our analysis to heterodimeric carriers that mediate the placental uptake of amino acids and antioxidant precursors. We focused on the L-type amino acid transporter (LAT)2/SLC7A8, the cystine/glutamate antiporter xCT/SLC7A11, and their chaperone 4F2hc/SLC3A2.

Methods

BeWo cells were exposed for two or five days to therapeutic concentrations of valproate, levetiracetam, carbamazepine, lamotrigine, or lacosamide. Transcript levels were measured by quantitative PCR. Levetiracetam effects on placental carriers were further explored using a tailored gene array.

Results

At five days, 30 μg/mL levetiracetam (high therapeutic concentrations) significantly reduced the expression of all studied genes (p < 0.05). Carbamazepine treatment was associated with lower SLC7A8 (LAT2) expression (p < 0.05), whereas valproate increased the transcript levels of this transporter by up to 2.0-fold (p < 0.01). Some of these effects were already observed after two incubation days. Lamotrigine did not alter gene expression, and lacosamide slightly elevated SLC3A2 levels (p < 0.05). The array analysis confirmed the trends observed for levetiracetam and identified additional affected genes.

Significance

Altered expression of placental heterodimeric transporters may represent a mechanism by which ASM affect fetal development. The placental effects are differential, with valproate, carbamazepine and levetiracetam as the more active compounds. The concentration-dependence of those ASM effects are in line with established dose-dependent teratogenicity implying that ASM doses should be adjusted during pregnancy with caution.

Introduction

Continuous supply of nutrients via the placenta is essential for optimal embryonic and fetal development. To acquire nutrients from maternal blood, placental trophoblasts rely on specialized carriers in their plasma membrane, mostly of the solute carrier (SLC) family (Lin et al., 2015; Palm and Thompson, 2017; Tetro et al., 2018). Some of these transport mechanisms additionally control the transplacental transfer of drugs taken by the pregnant mother, including antiseizure medications (ASMs) (Hasegawa et al., 2020; Ohman et al., 2005) or may be modulated by ASMs (Tetro et al., 2018). For instance, valproate affects the expression of transporters for carnitine (Lahjouji et al., 2004; Wu et al., 2004), folate (Fathe et al., 2014; Rubinchik-Stern et al., 2015), and thyroid hormones (Rubinchik-Stern et al., 2015) in placental brush-border membrane vesicles or in cultured cells and numerous transporters in rodent placentas in vivo (Jinno et al., 2020; Meir et al., 2016). We have additionally demonstrated that valproate modulates at the transcriptional level major carriers for folate and amino acids in term human placentas (Rubinchik-Stern et al., 2018) and in cultured placental tissue of gestational age 6–13 weeks (Tetro et al., 2019). Lamotrigine, carbamazepine and levetiracetam altered in the placental cell line BeWo the levels of carriers for folate, thyroid hormones, or both, including the L-type amino acid transporter LAT1/SLC7A5 (Rubinchik-Stern et al., 2015).

Given the emerging effects of ASMs on the growth and the structural and cognitive development of the fetus (Meador, 2020; Meador et al., 2013, 2020; Stephen et al., 2019; Tomson et al., 2018, 2011), in this work we extended our analysis to spotlight representative heterodimeric placental transporters. These transporters are comprised of a light chain (SLC7) and a heavy chain (SLC3). Among the heavy chains, rBAT (SLC3A1) is important for amino acid transport system b0,+, whereas 4F2hc/SLC3A2 interacts with transporters of several systems, including LAT1, LAT2 (SLC7A8) (system L) and the cystine/glutamate antiporter xCT (SLC7A11) (Gottesdiener et al., 1988). LAT-mediated transport of essential amino acids activates pro-growth pathways, whereas cystine helps protect against oxidative stress (McCracken and Edinger, 2013; Timmerman et al., 2013).

Section snippets

Reagents

Cell culture reagents were purchased from Biological Industries (Beit Haemek, Israel). The RNeasy mini-isolation kit was from Qiagen (Valencia, CA, U.S.A.). TaqMan reverse transcription reagents and fluorescent minor groove binder (MGB) probes were from Applied Biosystems (Foster City, CA, U.S.A.). Lacosamide was from UCB Pharma, Brussels, Belgium. All other reagents and drugs were purchased from Sigma-Aldrich (Rehovot, Israel).

Cell culture and treatments

The human placental trophoblastic choriocarcinoma BeWo cell line

Results

BeWo cells were sensitive to valproate, levetiracetam and carbamazepine, whereas the effects of lamotrigine and lacosamide were minimal. After a short incubation period (two days), valproate increased SLC7A8 (LAT2) and SLC7A11 (xCT) expression in a concentration-dependent manner, with 2.0-fold and 1.8-fold increases at 166 μg/mL valproate, respectively (p < 0.01) (Fig. 1A). Valproate effect on SLC7A8 expression was sustained at five days (Fig. 1B). Levetiracetam at its high therapeutic

Discussion

Fetal exposure to ASMs can produce structural malformations, cognitive deficits, and behavioral abnormalities, and has been associated with pregnancy complications (Stephen et al., 2019). Valproate is the most teratogenic ASM whereas the risk is lower with lamotrigine, levetiracetam, carbamazepine and oxcarbazepine (Kasradze et al., 2017; Meador et al., 2013; Stephen et al., 2019; Tomson et al., 2018). However, it has been suggested that even pregnancy-safer ASMs can harm the fetus at high

Funding

The study was supported by the Israel Science Foundation (ISF) Grant #2054/18. The sponsor was not involved in study design; collection, analysis and interpretation of data; writing of the report; and the decision to submit the article for publication.

Declaration of Competing Interest

Sara Eyal has received speaker honoraria from Megapharm, Israel. The other authors have no conflicts of interest.

Acknowledgments

We acknowledge the support of the Israel Science Foundation (Grant #506/13). Sara Eyal is affiliated with the David R. Bloom Centre for Pharmacy and Dr. Adolf and Klara Brettler Center for Research in Molecular Pharmacology and Therapeutics at The Hebrew University of Jerusalem, Israel.

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