Placental transfer of maraviroc in an ex vivo human cotyledon perfusion model and influence of ABC transporter expression.

Nowadays, antiretroviral therapy is recommended during pregnancy to prevent mother-to-child transmission of HIV. However, for many antiretroviral drugs, including maraviroc, a CCR5 antagonist, very little data exist regarding placental transfer. Besides, various factors may modulate this transfer, including efflux transporters belonging to the ATP-binding cassette (ABC) transporter superfamily. We investigated maraviroc placental transfer and the influence of ABC transporter expression on this transfer using the human cotyledon perfusion model. Term placentas were perfused ex vivo for 90 min with maraviroc (600 ng/ml) either in the maternal-to-fetal (n = 10 placentas) or fetal-to-maternal (n = 6 placentas) direction. Plasma concentrations were determined by ultra performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS). Fetal transfer rates (FTR) and clearance indexes (CLI) were calculated as ratios of fetal to maternal concentrations at steady state (mean values between 30 and 90 min) and ratios of FTR of maraviroc to that of antipyrine, respectively. ABC transporter gene expression levels were determined by quantitative reverse transcription (RT)-PCR and ABCB1 protein expression by Western blotting. For the maternal-to-fetal direction, the mean FTR and CLI were 8.0% ± 3.0 and 0.26 ± 0.07, respectively, whereas the mean CLI was 0.52 ± 0.23 for the fetal-to-maternal direction. We showed a significant inverse correlation between maraviroc CLI and ABCC2, ABCC10, and ABCC11 placental gene expression levels (P < 0.05). To conclude, we report a low maraviroc placental transfer probably involving ABC efflux transporters and thus in all likelihood associated with a limited fetal exposition. Nevertheless, these results would need to be supported by in vivo data obtained from paired maternal and cord blood samples.

ABC drug transporter and nuclear receptor expression in human cytotrophoblasts: influence of spontaneous syncytialization and induction by glucocorticoids.

OBJECTIVES: ABC transporters in the human placenta play a major role in protecting the fetus against potential toxic drugs. The glucocorticoid dexamethasone has been shown to induce ABCB1 expression in enterocytes and hepatocytes. However, in placental cells, little data exists either for dexamethasone, betamethasone or prednisone while these three glucocorticoids may be used during pregnancy. We investigated the modulation of placental ABC transporter and nuclear receptor expression by these drugs. METHODS: Cytotrophoblasts were isolated from normal full-term placentas. We first assessed the influence of spontaneous syncytialization on transporter and nuclear receptor gene expression by taking samples of cytotrophoblasts after 24, 48 and 72 h of cell culture (n = 7 placentas). Incubations were then conducted with dexamethasone (50 nM-1 µM), betamethasone (20-400 nM) and prednisone (50 nM-1 µM) versus no drug for 24 h (n = 6). mRNA expression was determined by qRT-PCR. RESULTS: Influence of syncytialization was observed only for ABCB1, ABCC2 and ABCC5 gene expression between t = 24 and 48 h (p < 0.05). Therefore, the following induction studies were conducted between t = 48 h and 72 h. Dexamethasone and betamethasone significantly induced ABCB1 gene expression by around 4-fold (p < 0.01 and 0.001, respectively). In parallel, 100 nM betamethasone decreased the glucocorticoid receptor gene expression by 22% (p < 0.01). Prednisone showed no effect on transporter or receptor expression. CONCLUSIONS: These results suggest that dexamethasone or betamethasone administration may decrease the maternal-fetal transfer of an associated treatment being ABCB1 substrate, which may be either protective or deleterious for the fetus depending on the treatment's therapeutic aim.