Ethanol Impairs NRF2/Antioxidant and Growth Signaling in the Intact Placenta In Vivo and in Human Trophoblasts

Modeling the human placenta: in vitro applications in developmental and reproductive toxicology

During its temporary tenure, the placenta has extensive and specialized functions that are critical for pre- and post-natal development. The consequences of chemical exposure in utero can have profound effects on the structure and function of pregnancy-associated tissues and the life-long health of the birthing person and their offspring. However, the toxicological importance and critical functions of the placenta to embryonic and fetal development and maturation have been understudied. This narrative will review early placental development in humans and highlight some in vitro models currently in use that are or can be applied to better understand placental processes underlying developmental toxicity due to in utero environmental exposures.

Ethanol inhibition of undifferentiated rat neural progenitor cell replication can be prevented by chlorogenic acid via the NFATc4/CSE signaling pathway

BACKGROUND

Prenatal ethanol exposure hinders oxidative stress-mediated neuroblast/neural progenitor cell proliferation by inhibiting G1-S transition, a process vital to neocortical development. We previously showed that ethanol elicits this redox imbalance by repressing cystathionine γ-lyase (CSE), the rate-limiting enzyme in the transsulfuration pathway in fetal brain and cultured cerebral cortical neurons. However, the mechanism by which ethanol impacts the CSE pathway in proliferating neuroblasts is not known. We conducted experiments to define the effects of ethanol on CSE regulation and the molecular signaling events that control this vital pathway. This enabled us to develop an intervention to prevent the ethanol-associated cytostasis.

METHODS

Spontaneously immortalized undifferentiated E18 rat neuroblasts from brain cerebral cortex were exposed to ethanol to mimic an acute consumption pattern in humans. We performed loss- and gain-of-function studies to evaluate whether NFATc4 is a transcriptional regulator of CSE. The neuroprotective effects of chlorogenic acid (CGA) against the effects of ethanol were assessed using ROS and GSH/GSSG assays as measures of oxidative stress, transcriptional activation of NFATc4, and expression of NFATc4 and CSE by qRT-PCR and immunoblotting.

RESULTS

Ethanol treatment of E18-neuroblast cells elicited oxidative stress and significantly reduced CSE expression with a concomitant decrease in NFATc4 transcriptional activation and expression. In parallel, inhibition of the calcineurin/NFAT pathway by FK506 exaggerated ethanol-induced CSE loss. In contrast, NFATc4 overexpression prevented loss of ethanol-induced CSE. CGA increased and activated NFATc4, amplified CSE expression, rescued ethanol-induced oxidative stress, and averted the cytostasis of neuroblasts by rescuing cyclin D1 expression.

CONCLUSIONS

These findings demonstrate that ethanol can perturb CSE-dependent redox homeostasis by impairing the NFATc4 signaling pathway in neuroblasts. Notably, ethanol-associated impairments were rescued by genetic or pharmacological activation of NFATc4. Furthermore, we found a potential role for CGA in mitigating the ethanol-related neuroblast toxicity with a compelling connection to the NFATc4/CSE pathway.

Effect of Postnatal Epigallocatechin-Gallate Treatment on Cardiac Function in Mice Prenatally Exposed to Alcohol

Prenatal alcohol exposure affects the cardiovascular health of the offspring. Epigallocatechin-3-gallate (EGCG) may be a protective agent against it, but no data are available regarding its impact on cardiac dysfunction. We investigated the presence of cardiac alterations in mice prenatally exposed to alcohol and the effect of postnatal EGCG treatment on cardiac function and related biochemical pathways. C57BL/6J pregnant mice received 1.5 g/kg/day (Mediterranean pattern), 4.5 g/kg/day (binge pattern) of ethanol, or maltodextrin until Day 19 of pregnancy. Post-delivery, treatment groups received EGCG-supplemented water. At post-natal Day 60, functional echocardiographies were performed. Heart biomarkers of apoptosis, oxidative stress, and cardiac damage were analyzed by Western blot. BNP and Hif1α increased and Nrf2 decreased in mice prenatally exposed to the Mediterranean alcohol pattern. Bcl-2 was downregulated in the binge PAE drinking pattern. Troponin I, glutathione peroxidase, and Bax increased in both ethanol exposure patterns. Prenatal alcohol exposure led to cardiac dysfunction in exposed mice, evidenced by a reduced ejection fraction, left ventricle posterior wall thickness at diastole, and Tei index. EGCG postnatal therapy restored the physiological levels of these biomarkers and improved cardiac dysfunction. These findings suggest that postnatal EGCG treatment attenuates the cardiac damage caused by prenatal alcohol exposure in the offspring.

Translation suppression underlies the restrained COVID-19 mRNA vaccine response in the high-risk immunocompromised group

Background

Immunocompromised (IC) patients show diminished immune response to COVID-19 mRNA vaccines (Co-mV). To date, there is no ‘empirical’ evidence to link the perturbation of translation, a rate-limiting step for mRNA vaccine efficiency (VE), to the dampened response of Co-mV.

Materials and methods

Impact of immunosuppressants (ISs), tacrolimus (T), mycophenolate (M), rapamycin/sirolimus (S), and their combinations on Pfizer Co-mV translation were determined by the Spike (Sp) protein expression following Co-mV transfection in HEK293 cells. In vivo impact of ISs on SARS-CoV-2 spike specific antigen (SpAg) and associated antibody levels (IgGSp) in serum were assessed in Balb/c mice after two doses (2D) of the Pfizer vaccine. Spike Ag and IgGSp levels were assessed in 259 IC patients and 50 healthy controls (HC) who received 2D of Pfizer or Moderna Co-mV as well as in 67 immunosuppressed solid organ transplant (SOT) patients and 843 non-transplanted (NT) subjects following three doses (3D) of Co-mV. Higher Co-mV concentrations and transient drug holidays were evaluated.

Results

We observed significantly lower IgGSP response in IC patients (p<0.0001) compared to their matched controls in 2D and 3D Co-mV groups. IC patients on M or S showed a profound dampening of IgGSP response relative to those that were not on these drugs. M and S, when used individually or in combination, significantly attenuated the Co-mV-induced Sp expression, whereas T did not exert significant influence. Sirolimus combo pretreatment in vivo significantly attenuated the Co-mV induced IgMSp and IgGSp production, which correlated with a decreasing trend in the early levels (after day 1) of Co-mV induced Sp immunogen levels. Neither higher Co-mV concentrations (6μg) nor withholding S for 1-day could overcome the inhibition of Sp protein levels. Interestingly, 3-days S holiday or using T alone rescued Sp levels in vitro.

Conclusions

This is the first study to demonstrate that ISs, sirolimus and mycophenolate inhibited Co-mV-induced Sp protein synthesis via translation repression. Selective use of tacrolimus or drug holiday of sirolimus can be a potential means to rescue translation-dependent Sp protein production. These findings lay a strong foundation for guiding future studies aimed at improving Co-mV responses in high-risk IC patients.

The effect of ethanol and nicotine on ER stress in human placental villous explants

•

Nicotine increased the GRP78/BiP protein in first trimester and term placental villous explants.

•

Nicotine can cause endoplasmic reticulum stress in human placenta.

•

Placental villous explants can be isolated from first trimester and term placenta to compare responses to toxic compounds.

Pregnant mothers continue smoking and drinking during pregnancy. To clarify the mechanisms of nicotine and ethanol toxicity during development, we have examined their effects on endoplasmic reticulum (ER) stress in human first trimester and term placental explants. First trimester and term human placental explants were treated with ethanol (2 ‰) or nicotine (15 µM), or their combination. The ER stress markers glucose regulated protein 78 (GRP78/BiP) and inositol requiring enzyme 1 α (IRE1α) were analyzed by immunoblotting. A statistically significant increase (p < 0.05) of GRP78/BiP by nicotine was noted in first trimester placental explants at 48 h, and in term placental explants at 24 h. Ethanol did not change protein expression of GRP78/BiP in either first trimester or term placental explants. IRE1α increased, although not statistically significantly, by all treatments in both first trimester and term placental explants. Thus, regardless of the known structural and functional differences in early and late placenta, both responded very similarly to the toxic compounds studied. These data support our earlier results in BeWo cells (Repo et al., 2014) implicating that nicotine induces ER stress in human placenta and may interfere with placental functions potentially disrupting fetal growth and development.

Spirostane saponins with a rearranged A/B ring system isolated from the rhizomes of Ophiopogon japonicus

In this study, the popular food and medicinal herb Ophiopogon japonicus was investigated alongside a 70% ethanol extract of its rhizomes, revealing twenty-three steroidal glycosides with four undescribed steroidal saponins, named ophiopogonols A-D. Among them, ophiopogonols A-B are two unusual spirostanols with a rearranged A/B ring system (5/7/6/5/5/6 ring system) that have not previously been identified in plants. The chemical structures of all isolated steroidal glycosides were elucidated by comprehensive analysis through chemical methods, HRESIMS, and NMR spectroscopy. Further, putative biosynthetic pathways for ophiopogonols A-B were proposed. In addition, based on traditional applications of O. japonicus, cytotoxic effects of the isolates were evaluated using human large cell lung carcinoma cells (NCI-H460 cells). Sprengerinin C displayed a remarkable cytotoxic effect with IC₅₀ values of 2.1 ± 0.8 μM by inducing apoptosis and G2/M phase cycle arrest in the NCI-H460 cell line.

Melatonin rescues cerebral ischemic events through upregulated tunneling nanotube-mediated mitochondrial transfer and downregulated mitochondrial oxidative stress in rat brain

BACKGROUND

Cerebral ischemic events, comprising of excitotoxicity, reactive oxygen production, and inflammation, adversely impact the metabolic-redox circuit in highly active neuronal metabolic profile which maintains energy-dependent brain activities. Therefore, we investigated neuro-regenerative potential of melatonin (Mel), a natural biomaterial secreted by pineal gland.

METHODS

We specifically determined whether Mel could influence tunneling nanotubes (TNTs)-mediated transfer of functional mitochondria (Mito) which in turn may alter membrane potential, oxidative stress and apoptotic factors. In vitro studies assessed the effects of Mito on levels of cytochrome C, mitochondrial transfer, reactive oxygen species, membrane potential and mass, which were all further enhanced by Mel pre-treatment, whereas in vivo studies examined brain infarct area (BIA), neurological function, inflammation, brain edema and integrity of neurons and myelin sheath in control, ischemia stroke (IS), IS + Mito and IS + Mel-Mito group rats.

RESULTS

Results showed that Mel pre-treatment significantly increased mitochondrial transfer and antioxidants, and inhibited apoptosis. Mel-pretreated Mito also significantly reduced BIA with improved neurological function. Apoptotic, oxidative-stress, autophagic, mitochondrial/DNA-damaged biomarkers indices were also improved.

CONCLUSION

Conclusively, Mel is a potent biomaterial which could potentially impart neurogenesis through repairing impaired metabolic-redox circuit via enhanced TNT-mediated mitochondrial transfer, anti-oxidation, and anti-apoptotic activities in ischemia.

Sildenafil augments fetal weight and placental adiponectin in gestational testosterone-induced glucose intolerant rats

Testosterone induces intra-uterine growth restriction (IUGR) with maternal glucose dysregulation and oxidant release in various tissues. Adiponectin, which modulates the antioxidant nuclear factor erythroid 2-related factor 2 (Nrf2) signaling is expressed in the placenta and affects fetal growth. Sildenafil, a phosphodiesterase type 5 inhibitor (PDE5i), used mainly in erectile dysfunction has been widely studied as a plausible pharmacologic candidate in IUGR. Therefore, the present study sought to determine the effect of PDE5i on placental adiponectin/Nrf2 pathway in gestational testosterone-induced impaired glucose tolerance and fetal growth. Fifteen pregnant Wistar rats were allotted into three groups (n = 5/group) receiving vehicles (Ctr; distilled water and olive oil), testosterone propionate (Tes; 3.0 mg/kg; sc) or combination of testosterone propionate (3.0 mg/kg; sc) and sildenafil (50.0 mg/kg; po) from gestational day 14-19. On gestational day 20, plasma and placenta homogenates were obtained for biochemical analysis as well as fetal biometry. Pregnant rats exposed to testosterone had 4-fold increase in circulating testosterone compared with control (20.9 ± 2.8 vs 5.1 ± 1.7 ng/mL; p < 0.05) whereas placenta testosterone levels were similar in testosterone- and vehicle-treated rats. Exposure to gestational testosterone caused reduction in fetal and placental weights, placental Nrf2 and adiponectin. Moreover, impaired glucose tolerance, elevated plasma triglyceride-glucose (TyG) index, placental triglyceride, total cholesterol, lactate, malondialdehyde and alanine aminotransferase were observed in testosterone-exposed rats. Treatment with sildenafil improved glucose tolerance, plasma TyG index, fetal and placental weights and reversed placental adiponectin in testosterone-exposed pregnant rats without any effect on placental Nrf2. Therefore, in testosterone-exposed rats, sildenafil improves impaired glucose tolerance, poor fetal outcome which is accompanied by augmented placental adiponectin regardless of depressed Nrf2.

Epigallocatechin Gallate Ameliorates the Effects of Prenatal Alcohol Exposure in a Fetal Alcohol Spectrum Disorder-Like Mouse Model

Fetal alcohol spectrum disorder is the main preventable cause of intellectual disability in the Western world. Although binge drinking is the most studied prenatal alcohol exposure pattern, other types of exposure, such as the Mediterranean, are common in specific geographic areas. In this study, we analyze the effects of prenatal alcohol exposure in binge and Mediterranean human drinking patterns on placenta and brain development in C57BL/6J mice. We also assess the impact of prenatal treatment with the epigallocatechin-3-gallate antioxidant in both groups. Study experimental groups for Mediterranean or binge patterns: (1) control; (2) ethanol; (3) ethanol + epigallocatechin-3-gallate. Brain and placental tissue were collected on gestational Day 19. The molecular pathways studied were fetal and placental growth, placental angiogenesis (VEGF-A, PLGF, VEGF-R), oxidative stress (Nrf2), and neurodevelopmental processes including maturation (NeuN, DCX), differentiation (GFAP) and neural plasticity (BDNF). Prenatal alcohol exposure resulted in fetal growth restriction and produced imbalances of placental angiogenic factors. Moreover, prenatal alcohol exposure increased oxidative stress and caused significant alterations in neuronal maturation and astrocyte differentiation. Epigallocatechin-3-gallate therapy ameliorated fetal growth restriction, attenuated alcohol-induced changes in placental angiogenic factors, and partially rescued neuronal nuclear antigen (NeuN), (doublecortin) DCX, and (glial fibrillary acidic protein) GFAP levels. Any alcohol consumption (Mediterranean or binge) during pregnancy may generate a fetal alcohol spectrum disorder phenotype and the consequences may be partially attenuated by a prenatal treatment with epigallocatechin-3-gallate.

Cellular and Transcriptional Adaptation of Bovine Granulosa Cells Under Ethanol-Induced Stress In Vitro

AIMS

Granulosa cells (GCs) are the major cellular component in a follicular microenvironment and play an indispensable role in ovarian function. This study was conducted to investigate the effects of ethanol exposure on the cellular and transcriptional changes of ovarian GCs.

METHODS

For this purpose, bovine GCs were exposed to different concentrations of ethanol (0, 50, 100, 200, 500 and 1000) to mimic the effects of alcohol in in vitro. Subsequently, 100 and 1000 mM concentrations were discarded from further experiments, as 100 mM was not different from 50 mM, and 1000 mM was supertoxic to the cells.

RESULTS

The results showed that there was a gradual loss of cell viability with the increase of the ethanol concentration, i.e. lowest viability was observed at the highest concentration (1000 mM), which is further supported by cell proliferation assay. Mitochondrial activity decreased significantly at higher concentrations. The expression of NRF2 decreased significantly (P < 0.05) in ethanol-exposed cells compared with the cells in the control group at the 6-h time point, whereas the expression was increased in 500 mM concentration at the 24-h time point. The expression of antioxidant genes, downstream to Nrf2-pathway activation, showed that overall expression pattern similar to NRF2.

CONCLUSION

The result of this study prompted us to postulate that ethanol exposure decreases the ability of GCs to handle stress by downregulating the expression of genes involved in Nrf2-pathway.

The effects of a technical mixture of naphthenic acids on placental trophoblast cell function

There is considerable concern that naphthenic acids (NA) related to oil extraction can negatively impact reproduction in mammals, yet the mechanisms are unknown. Since placental dysfunction is central to many adverse pregnancy outcomes, the goal of this study was to determine the effects of NA exposure on placental trophoblast cell function. HTR-8/SVneo cells were exposed to a commercial technical NA mixture for 24 hours to assess transcriptional regulation of placentation-related pathways and functional assessment of migration, invasion, and angiogenesis. Pathway analysis suggests that NA treatment resulted in increased epithelial-to-mesenchymal transition. However, there was reduced migration and invasive potential. NA treatment increased angiogenesis-related pathways with a concomitant increase in tube formation. Since decreased trophoblast invasion/migration and aberrant angiogenesis have been associated with placental dysfunction, these findings suggest that it is biologically plausible that exposure to NA may result in altered placental development and/or function.