Aiko Aoki

Role of autophagy in oocytogenesis, embryogenesis, implantation, and pathophysiology of pre‐eclampsia

Autophagy is a well‐conserved mechanism in cells from yeast to mammals, and autophagy maintains homeostasis against stress. The role of autophagy was originally shown to be a mechanism of energy production under starvation. In fact, multiple lines of evidence reveal that autophagy has numerous functions, such as protection from stress, energy regulation, immune regulation, differentiation, proliferation, and cell death. In the field of reproduction, the role of autophagy in implantation, embryogenesis, placentation, and delivery has become clearer. In addition, recent study has elucidated that the placenta has the ability to protect extraplacental cells from virus infection by activating autophagy. During resent research into autophagy, several issues have occurred in the interpretation of the autophagy status. In this review, we discuss the relation between autophagy and reproductive events, and show the importance of autophagy for placentation and pre‐eclampsia.

Aberrant methylation of H19-DMR acquired after implantation was dissimilar in soma versus placenta of patients with Beckwith–Wiedemann syndrome†

Gain of methylation (GOM) at the H19‐differentially methylated region (H19‐DMR) is one of several causative alterations in Beckwith–Wiedemann syndrome (BWS), an imprinting‐related disorder. In most patients with epigenetic changes at H19‐DMR, the timing of and mechanism mediating GOM is unknown. To clarify this, we analyzed methylation at the imprinting control regions of somatic tissues and the placenta from two unrelated, naturally conceived patients with sporadic BWS. Maternal H19‐DMR was abnormally and variably hypermethylated in both patients, indicating epigenetic mosaicism. Aberrant methylation levels were consistently lower in placenta than in blood and skin. Mosaic and discordant methylation strongly suggested that aberrant hypermethylation occurred after implantation, when genome‐wide de novo methylation normally occurs. We expect aberrant de novo hypermethylation of H19‐DMR happens to a greater extent in embryos than in placentas, as this is normally the case for de novo methylation. In addition, of 16 primary imprinted DMRs analyzed, only H19‐DMR was aberrantly methylated, except for NNAT DMR in the placental chorangioma of Patient 2. To our knowledge, these are the first data suggesting when GOM of H19‐DMR occurs.

Autophagy regulation in preeclampsia: Pros and cons

Autophagy is an evolutionarily conserved process in eukaryotes to maintain cellular homeostasis against stress. This process has two main functions: producing energy and quality control of intracellular proteins. During early pregnancy, extravillous trophoblasts (EVTs) invade the uterine myometrium and migrate along the lumina of spiral arterioles under hypoxic and low-nutrient conditions. Autophagy activation is observed in EVTs under these conditions, suggesting that EVTs use autophagy for adjusting to such harsh conditions. On the other hand, soluble endoglin, which is increased in sera in preeclamptic cases, inhibits autophagy in vitro, resulting in suppression of EVT functions, invasion and vascular remodeling. In addition, p62/SQSTM1, a substrate degraded by autophagy, accumulates in EVTs in preeclamptic placental biopsy samples, exhibiting impaired autophagy in vivo. There are, however, some opposing reports in which autophagy activation, an increase of autophagy vacuoles or LC3 dots, was more frequently observed in preeclamptic or FGR placentas than in normal pregnancy. Thus, changes in autophagy status are seen in preeclamptic placentas, but the mechanism by which autophagy modulates biological changes in the placentas is still unknown. Recently, there is increasing evidence that autophagy is involved in maintaining pregnancy. This review introduces the role of autophagy for maintaining pregnancy and its correlation with preeclampsia.

Beckwith–Wiedemann syndrome with placental chorangioma due to H19-differentially methylated region hypermethylation: A case report

Beckwith–Wiedemann syndrome (BWS) is a common overgrowth syndrome that involves abdominal wall defects, macroglossia, and gigantism. It is sometimes complicated by placental tumor and polyhydramnios. We report a case of BWS, prenatally diagnosed with ultrasonography. A large and well‐circumscribed tumor also existed on the fetal surface of the placenta, which was histologically diagnosed as chorangioma after delivery. Polyhydramnios was obvious and the fetal heart enlarged progressively during pregnancy. Because the biophysical profiling score dropped to 4 points at 33 weeks of gestation, we carried out cesarean section. By epigenetic analysis, H19‐differentially methylated region hypermethylation was observed in the placental tumor, normal placental tissue, and cord blood mononuclear cells. This is the first report of BWS with placental tumor due to H19‐differentially methylated region hypermethylation.

Massive postpartum hemorrhage after chemotherapy in a patient with acute promyelocytic leukemia.

A pregnant woman was diagnosed with acute promyelocytic leukemia at 38 weeks of gestation. Induction of labor was successful, and the patient delivered a healthy male baby. Soon after delivery, she was treated with chemotherapy using all‐trans‐retinoic acid (ATRA). The number of white blood cells was increased on the fifth postpartum day and retinoic acid syndrome (RAS) was considered a concern. On the sixth postpartum day, remission induction chemotherapy with idarubicin and cytosine arabinoside was started. On the seventh postpartum day, massive uterine bleeding of more than 1300 mL suddenly occurred. As administration of cytotoxic agents may induce disseminated intravascular coagulation, we should take care to avoid uterine bleeding after chemotherapy in acute promyelocytic leukemia cases treated soon after delivery.

Autophagy in Preeclampsia

Autophagy is an evolutionarily conserved process in eukaryotes by which cytoplasmic cargo sequestered inside double-membrane vesicles is delivered to the lysosome for degradation. Recently, there is increasing evidence that modulating autophagy accumulates during pregnancy. In early pregnancy, trophoblasts and the fetus experience hypoxic and low-nutrient conditions; nevertheless, extravillous trophoblasts (EVTs) invade the uterine myometrium up to one third of its depth and migrate along the lumina of spiral arterioles, replacing the maternal endothelial lining. An enhancement of autophagy induced by physiological hypoxia occurs during the invasion and vascular remodeling in EVTs. However, soluble endoglin, which is increased in sera in preeclamptic cases, suppresses EVT invasion or vascular remodeling by inhibiting autophagy in vivo. In addition, a substance selectively degraded by autophagy, p62/SQSTM1, accumulates in EVT cells in preeclamptic placental biopsy samples showing impaired autophagy in vivo. On the other hand, there are some reports about autophagy activation in preeclamptic placentas. Though changes in autophagy may affect the fates of mothers and babies, controversy remains for the evaluation of autophagy status in preeclampsia. In this chapter, we will introduce the role of autophagy in embryogenesis, implantation, and maintaining pregnancy and discuss the autophagy status in preeclampsia.

Neutrophil Depletion Exacerbates Pregnancy Complications, Including Placental Damage, Induced by Silica Nanoparticles in Mice

Recent advances in nanotechnology have led to the development of nanoparticles with innovative functions in various fields. However, the biological effects of nanoparticles—particularly those on the fetus—need to be investigated in detail, because several previous studies have shown that various nanoparticles induce pregnancy complications in mice. In this regard, our previous findings in mice suggested that the increase in peripheral neutrophil count induced by treatment with silica nanoparticles with a diameter of 70 nm (nSP70) may play a role in the associated pregnancy complications. Therefore, here, we sought to define the role of neutrophils in nSP70-induced pregnancy complications. The peripheral neutrophil count in pregnant BALB/c mice at 24 h after treatment with nSP70 was significantly higher than in saline-treated mice. In addition, maternal body weight, uterine weight, and the number of fetuses in nSP70-treated mice pretreated with anti-antibodies, which deplete neutrophils, were significantly lower than those in nSP70-treated mice pretreated with phosphate-buffered saline or isotype-matched control antibodies. Histology revealed that neutrophil depletion increased nSP70-induced placental damage from the decidua through the spongiotrophoblast layer and narrowed spiral arteries in the placentae. In addition, depletion of neutrophils augmented nSP70-induced cytotoxicity to fetal vessels, which were covered with endothelium. The rate of apoptotic cell death was significantly higher in the placentae of anti-nSP70-treated mice than in those from mice pretreated with isotype-matched control antibodies. Therefore, impairment of placental vessels and apoptotic cell death due to nSP70 exposure is exacerbated in the placentae of nSP70-treated mice pretreated with anti-antibodies. Depletion of neutrophils worsens nSP70-induced pregnancy complications in mice; this exacerbation was due to enhanced impairment of placental vessels and increased apoptotic cell death in maternal placentae. Our results provide basic information regarding the mechanism underlying silica-nanoparticle-induced pregnancy complications.

The Role of Autophagy in Maintaining Pregnancy

Autophagy is an evolutionarily conserved process in eukaryotes by which cytoplas‐ mic cargo sequestered inside double‐membrane vesicles is delivered to the lysosome for degradation. In early pregnancy, trophoblasts and the fetus experience hypoxic and low‐nutrient conditions; nevertheless, extravillous trophoblasts (EVTs) invade the uterine myometrium up to one‐third of its depth and migrate along the lumina of spiral arterioles, replacing the maternal endothelial lining. An enhancement of autophagy induced by physiological hypoxia takes part in the invasion and vascular remodeling in EVTs. On the other hand, soluble endoglin, which increased in sera in preeclamptic cases, suppresses EVT‐invasion or ‐vascular remodeling by inhibiting autophagy In vitro. In addition, a substance selectively degraded by autophagy, p62/ SQSTM1, accumulates in EVT cells in preeclamptic placental biopsy samples showing impaired autophagy in vivo. Thus, alternation of autophagy could affect fates of mothers and babies. Recently increasing evidence of modulating autophagy has accumulated during pregnancy. In this chapter, we introduce the role of autophagy in embryogenesis, implantation, and maintaining pregnancy.