The potentially protective role of ATP-binding cassette transporters in preeclampsia via Nrf2

Iron metabolism and ferroptosis: A pathway for understanding preeclampsia

Preeclampsia (PE) is a serious medical condition that poses a significant health risk to women and children worldwide, particularly in the middle- and low-income countries. It is a complex syndrome that occurs as a result of abnormal pregnancy. Hypertension is the most common symptom of PE, with proteinuria and specific organ systems as detrimental targets. PE's pathogenesis is diverse, and its symptoms can overlap with other diseases. In early pregnancy, when the placenta takes over control, oxidative stress may be closely associated with ferroptosis, a type of cell death caused by intracellular iron accumulation. Ferroptosis in the placenta is defined by redox-active iron availability, loss of antioxidant capacity and phospholipids containing polyunsaturated fatty acids (PUFA) oxidation. Recent studies suggest a compelling potential link between ferroptosis and PE. In this article, we comprehensively review the current understanding of PE and discuss one of its emerging underlying mechanisms, the ferroptosis pathway. We also provide perspective and analysis on the implications of this process in the diagnosis, prevention, and treatment of preeclampsia. We aim to bridge the gap between clinicians and basic scientists in understanding this harmful disease and challenge the research community to put more effort into this exciting new area.

The nuclear factor erythroid 2-related factor 2/p53 axis in breast cancer

One of the most important factors involved in the response to oxidative stress (OS) is the nuclear factor erythroid 2-related factor 2 (Nrf2), which regulates the expression of components such as antioxidative stress proteins and enzymes. Under normal conditions, Kelch-like ECH-associated protein 1 (Keap1) keeps Nrf2 in the cytoplasm, thus preventing its translocation to the nucleus and inhibiting its role. It has been established that Nrf2 has a dual function; on the one hand, it promotes angiogenesis and cancer cell metastasis while causing resistance to drugs and chemotherapy. On the other hand, Nrf2 increases expression and proliferation of glutathione to protect cells against OS. p53 is a tumour suppressor that activates the apoptosis pathway in aging and cancer cells in addition to stimulating the glutaminolysis and antioxidant pathways. Cancer cells use the antioxidant ability of p53 against OS. Therefore, in the present study, we discussed function of Nrf2 and p53 in breast cancer (BC) cells to elucidate their role in protection or destruction of cancer cells as well as their drug resistance or antioxidant properties.

Modulation of NRF2/KEAP1 Signaling in Preeclampsia

Placentation is a key and tightly regulated process that ensures the normal development of the placenta and fetal growth. Preeclampsia (PE) is a hypertensive pregnancy-related disorder involving about 5-8% of all pregnancies and clinically characterized by de novo maternal hypertension and proteinuria. In addition, PE pregnancies are also characterized by increased oxidative stress and inflammation. The NRF2/KEAP1 signaling pathway plays an important role in protecting cells against oxidative damage due to increased reactive oxygen species (ROS) levels. ROS activate NRF2, allowing its binding to the antioxidant response element (ARE) region present in the promoter of several antioxidant genes such as heme oxygenase, catalase, glutathione peroxidase and superoxide dismutase that neutralize ROS, protecting cells against oxidative stress damages. In this review, we analyze the current literature regarding the role of the NRF2/KEAP1 pathway in preeclamptic pregnancies, discussing the main cellular modulators of this pathway. Moreover, we also discuss the main natural and synthetic compounds that can regulate this pathway in in vivo and in vitro models.

LINC00240/miR-155 axis regulates function of trophoblasts and M2 macrophage polarization via modulating oxidative stress-induced pyroptosis in preeclampsia

Background

This study aimed to investigate the effects of LINC00240/miR-155/Nrf2 axis on trophoblast function and macrophage polarization in the pathogenesis of preeclampsia.

Methods

Bindings between LINC00240, miR-155 and Nrf2 were validated by dual luciferase reporter assay or RNA-immunoprecipitation. Cell proliferation, migration, invasion, and pyroptosis were detected by CCK-8, clone formation, wound healing, Transwell system, and flow cytometry, respectively. Macrophage polarization was tested by flow cytometry. The expression levels of LINC00240, miR-155, Nrf2, and oxidative stress and pyroptosis-related markers in in vitro and in vivo preeclampsia models were analyzed by qPCR, western blot, or ELISA assays. Blood pressure, urine protein levels, liver and kidney damages, and trophoblast markers in placenta tissues were further studied in vivo.

Results

Placenta tissues from preeclampsia patients and animals showed decreased LINC00240 and Nrf2 and increased miR-155 expression levels, and the decreased M2 macrophage polarization. LINC00240 directly bound and inhibited expression of miR-155, which then inhibited oxidative stress-induced pyroptosis, promoting proliferation, migration and invasion abilities of trophoblasts, and M2 macrophage polarization. Inhibition of miR-155 led to increased Nrf2 expression and similar changes as LINC00240 overexpression in trophoblast function and macrophage polarization. Overexpression of LINC00240 in in vivo preeclampsia model decreased blood pressure, urine protein, liver and kidney damages, increased fetal weight and length, and induced trophoblast function and M2 macrophage polarization.

Conclusion

LINC00240 inhibited symptoms of preeclampsia through regulation on miR-155/Nrf2 axis, which suppressed oxidative stress-induced pyroptosis to improve trophoblast function and M2 macrophage polarization. LINC00240 could be a potential therapeutic target for preeclampsia.

Puerariae lobatae Radix Alleviates Pre-Eclampsia by Remodeling Gut Microbiota and Protecting the Gut and Placental Barriers

Pre-eclampsia (PE) is a serious pregnancy complication, and gut dysbiosis is an important cause of it. Puerariae lobatae Radix (PLR) is a medicine and food homologous species; however, its effect on PE is unclear. This study aimed to investigate the efficacy of PLR in alleviating PE and its mechanisms. We used an NG-nitro-L-arginine methyl ester (L-NAME)-induced PE mouse model to examine the efficacy of preventive and therapeutic PLR supplementation. The results showed that both PLR interventions alleviated hypertension and proteinuria, increased fetal and placental weights, and elevated the levels of VEGF and PlGF. Moreover, PLR protected the placenta from oxidative stress via activating the Nrf2/HO-1/NQO1 pathway and mitigated placental damage by increasing intestinal barrier markers (ZO-1, Occludin, and Claudin-1) expression and reducing lipopolysaccharide leakage. Notably, preventive PLR administration corrected gut dysbiosis in PE mice, as evidenced by the increased abundance and positive interactions of beneficial bacteria including Bifidobacterium, Blautia, and Turicibacter. Fecal microbiota transplantation confirmed that the gut microbiota partially mediated the beneficial effects of PLR on PE. Our findings revealed that modulating the gut microbiota is an effective strategy for the treatment of PE and highlighted that PLR might be used as an intestinal nutrient supplement in PE patients.

NRF2 Serves a Critical Role in Regulation of Immune Checkpoint Proteins (ICPs) During Trophoblast Differentiation

Using cultured human trophoblast stem cells (hTSCs), mid-gestation human trophoblasts in primary culture, and gene-targeted mice, we tested the hypothesis that the multinucleated syncytiotrophoblast (SynT) serves a critical role in pregnancy maintenance through production of key immune modulators/checkpoint proteins (ICPs) under control of the O2-regulated transcription factor, NRF2/NFE2L2. These ICPs potentially act at the maternal-fetal interface to protect the hemiallogeneic fetus from rejection by the maternal immune system. Using cultured hTSCs, we observed that several ICPs involved in the induction and maintenance of immune tolerance were markedly upregulated during differentiation of cytotrophoblasts (CytTs) to SynT. These included HMOX1, kynurenine receptor, aryl hydrocarbon receptor, PD-L1, and GDF15. Intriguingly, NRF2, C/EBPβ, and PPARγ were markedly induced when CytTs fused to form SynT in a 20% O2 environment. Notably, when hTSCs were cultured in a hypoxic (2% O2) environment, SynT fusion and the differentiation-associated induction of NRF2, C/EBPβ, aromatase (CYP19A1; SynT differentiation marker), and ICPs were blocked. NRF2 knockdown also prevented induction of aromatase, C/EBPβ and the previously mentioned ICPs. Chromatin immunoprecipitation-quantitative PCR revealed that temporal induction of the ICPs in hTSCs and mid-gestation human trophoblasts cultured in 20% O2 was associated with increased binding of endogenous NRF2 to putative response elements within their promoters. Moreover, placentas of 12.5 days postcoitum mice with a global Nrf2 knockout manifested decreased mRNA expression of C/ebpβ, Pparγ, Hmox1, aryl hydrocarbon receptor, and Nqo1, another direct downstream target of Nrf2, compared with wild-type mice. Collectively, these compelling findings suggest that O2-regulated NRF2 serves as a key regulator of ICP expression during SynT differentiation.

Activation of Nrf2 signaling protects hypoxia-induced HTR-8/SVneo cells against ferroptosis

AIM

This article aims to investigate the possible mechanism by which nuclear factor erythroid 2-related factor 2 (Nrf2) signaling exerts protective effects on the progression of preeclampsia (PE).

METHODS

HTR-8/SVneo cells were cultured under hypoxic conditions to establish PE cell model. Cell viability and invasion were respectively examined by CCK-8 assay and transwell assay. The detection of oxidative stress and Fe²⁺ content was carried out by corresponding commercial kits, and the expression of corresponding proteins and genes was detected by western blot and qPCR. After Nrf2 was overexpressed in HTR-8/SVneo cells, the above assays were conducted to confirm the exact effects of Nrf2 activation on ferroptosis.

RESULTS

Hypoxia reduced the invasion of HTR-8/SVneo cells, induced oxidative stress (upregulated levels of glutathione [GSH], malondialdehyde [MDA], and reactive oxygen species [ROS]), and induced ferroptosis which exhibited by upregulated Fe²⁺ and downregulated expression of solute carrier family 7 member 11/System xCT (SCL7A11), glutathione peroxidase 4 (GPX4), and ferroportin1 (FPN1). Meanwhile, hypoxia promoted the translocation of Nrf2 to the nucleus, leading to Nrf2/HO-1 signaling activation. These changes upon hypoxia induction were strengthened by ferric ammonium citrate (FAC) but were abolished by deferoxamine (DFO). Moreover, Nrf2 overexpression in hypoxia-induced HTR-8/SVneo cells exerted inhibitory effects on levels of GSH, MDA, ROS, and Fe²⁺ , and promotive effects on Nrf2/HO-1 signaling activation and expression of SCL7A11, GPX4, and FPN1, indicating that Nrf2 overexpression decreased oxidative stress and ferroptosis in hypoxia-induced HTR-8/SVneo cells.

CONCLUSION

Collectively, activation of Nrf2 signaling alleviated hypoxia-induced invasion lacking, oxidative stress, and ferroptosis in hypoxia-induced HTR-8/SVneo cells, suggesting that Nrf2 signaling activation play a protective role in PE, which can provide instructions for the targeted treatment of PE.

1-O-Hexyl-2,3,5-Trimethylhydroquinone Ameliorates the Development of Preeclampsia through Suppression of Oxidative Stress and Endothelial Cell Apoptosis

1-O-Hexyl-2,3,5-trimethylhydroquinone (HTHQ), a potent nuclear factor-E2-related factor 2 (Nrf2) activator, has potent antioxidant activity by scavenging reactive oxygen species (ROS). However, the role of HTHQ on the development of preeclampsia (PE) and the underlying mechanisms have barely been explored. In the present study, PE model was induced by adenovirus-mediated overexpression of soluble fms-like tyrosine kinase 1 (sFlt-1) in pregnant mice. The results showed that HTHQ treatment significantly relieved the high systolic blood pressure (SBP) and proteinuria and increased the fetal weight and fetal weight/placenta weight in preeclamptic mice. Furthermore, we found that HTHQ treatment significantly decreased soluble endoglin (sEng), endothelin-1 (ET-1), and activin A and restored vascular endothelial growth factor (VEGF) in preeclamptic mice. In addition, HTHQ treatment inhibited oxidative stress and endothelial cell apoptosis by increasing the levels of Nrf2 and its downstream haemoxygenase-1 (HO-1) protein. In line with the data in vivo, we discovered that HTHQ treatment attenuated oxidative stress and cell apoptosis in human umbilical vein endothelial cells (HUVECs) following hypoxia and reperfusion (H/R), and the HTHQ-mediated protection was lost after transfected with siNrf2. In conclusion, these results suggested that HTHQ ameliorates the development of preeclampsia through suppression of oxidative stress and endothelial cell apoptosis.

Hypertensive disorders of pregnancy and the risk of chronic kidney disease: A Swedish registry-based cohort study

BACKGROUND

Hypertensive disorders of pregnancy (HDP) (preeclampsia, gestational hypertension) are associated with an increased risk of end-stage kidney disease (ESKD). Evidence for associations between HDP and chronic kidney disease (CKD) is more limited and inconsistent. The underlying causes of CKD are wide-ranging, and HDP may have differential associations with various aetiologies of CKD. We aimed to measure associations between HDP and maternal CKD in women who have had at least one live birth and to identify whether the risk differs by CKD aetiology.

METHODS AND FINDINGS

Using data from the Swedish Medical Birth Register (MBR), singleton live births from 1973 to 2012 were identified and linked to data from the Swedish Renal Register (SRR) and National Patient Register (NPR; up to 2013). Preeclampsia was the main exposure of interest and was treated as a time-dependent variable. Gestational hypertension was also investigated as a secondary exposure. The primary outcome was maternal CKD, and this was classified into 5 subtypes: hypertensive, diabetic, glomerular/proteinuric, tubulointerstitial, and other/nonspecific CKD. Cox proportional hazard regression models were used, adjusting for maternal age, country of origin, education level, antenatal BMI, smoking during pregnancy, gestational diabetes, and parity. Women with pre-pregnancy comorbidities were excluded. The final sample consisted of 1,924,409 women who had 3,726,554 singleton live births. The mean (±SD) age of women at first delivery was 27.0 (±5.1) years. Median follow-up was 20.7 (interquartile range [IQR] 9.9-30.0) years. A total of 90,917 women (4.7%) were diagnosed with preeclampsia, 43,964 (2.3%) had gestational hypertension, and 18,477 (0.9%) developed CKD. Preeclampsia was associated with a higher risk of developing CKD during follow-up (adjusted hazard ratio [aHR] 1.92, 95% CI 1.83-2.03, p < 0.001). This risk differed by CKD subtype and was higher for hypertensive CKD (aHR 3.72, 95% CI 3.05-4.53, p < 0.001), diabetic CKD (aHR 3.94, 95% CI 3.38-4.60, p < 0.001), and glomerular/proteinuric CKD (aHR 2.06, 95% CI 1.88-2.26, p < 0.001). More modest associations were observed between preeclampsia and tubulointerstitial CKD (aHR 1.44, 95% CI 1.24-1.68, p < 0.001) or other/nonspecific CKD (aHR 1.51, 95% CI 1.38-1.65, p < 0.001). The risk of CKD was increased after preterm preeclampsia, recurrent preeclampsia, or preeclampsia complicated by pre-pregnancy obesity. Women who had gestational hypertension also had increased risk of developing CKD (aHR 1.49, 95% CI 1.38-1.61, p < 0.001). This association was strongest for hypertensive CKD (aHR 3.13, 95% CI 2.47-3.97, p < 0.001). Limitations of the study are the possibility that cases of CKD were underdiagnosed in the national registers, and some women may have been too young to have developed symptomatic CKD despite the long follow-up time. Underreporting of postpartum hypertension is also possible.

CONCLUSIONS

In this study, we found that HDP are associated with increased risk of maternal CKD, particularly hypertensive or diabetic forms of CKD. The risk is higher after preterm preeclampsia, recurrent preeclampsia, or preeclampsia complicated by pre-pregnancy obesity. Women who experience HDP may benefit from future systematic renal monitoring.

Implication of nuclear factor-erythroid 2-like 2/heme oxygenase 1 pathway in the protective effects of coenzyme Q10 against preeclampsia-like in a rat model

BACKGROUND

Preeclampsia has ranked as one of the leading causes of both maternal and prenatal morbidity and mortality around the world. The hypotensive effect of coenzyme Q10 has been widely reported in preeclampsia rat model. However, the detailed mechanism remains unclear.

METHODS

L-NAME was utilized to establish the preeclampsia rat model. Biomarker assessments were performed to identify the levels of vascular factors including soluble fms-like tyrosine kinase (sFlt-1) and placental growth factor (PlGF), the circulating cytokines including interleukin 6, tumor necrosis factor α and interleukin 1β, and oxidative stress factors including malondialdehyde, H₂ O₂ , glutathione, superoxide dismutase, glutathione peroxidase, and Catalase. QRT-PCR was used to demonstrate the levels of cytokines in placenta tissues, and Western blot was performed to estimate the nuclear factor-erythroid 2-like 2 (Nrf2) and heme oxygenase 1 (HO-1) protein levels.

RESULTS

Coenzyme Q10 treatment decreased the blood pressure in rat model with preeclampsia by regulating the circulating levels of sFlt-1 and PlGF. Coenzyme Q10 attenuated serum and placental inflammation and oxidative stress in L-NAME-induced preeclampsia rats. Coenzyme Q10 activated the placental Nrf2/HO-1 pathway in L-NAME-induced preeclampsia rats.

CONCLUSION

Coenzyme Q10 attenuated placental inflammatory and oxidative stress, thereby protecting the rats against preeclampsia by activating the Nrf2/HO-1 pathway.

Biomarkers of placental redox imbalance in pregnancies with preeclampsia and consequent perinatal outcomes

OBJECTIVE

To compare redox and inflammatory markers between normal and PE-derived placentas and to evaluate the relationship between placental redox imbalance markers and perinatal outcomes in pregnancies with PE.

METHODS

This was a cross-sectional study conducted at the maternity hospital of a university hospital in Maceio-Alagoas, Brazil, in 2017, including women diagnosed with PE and healthy pregnant women and their conceptuses. After screening, standardized questionnaires containing socioeconomic, clinical, obstetric and anthropometric data were applied. After delivery, placental samples were collected for quantification of biomarkers of redox imbalance (catalase - CAT; malondialdehyde - MDA; hydrogen peroxide - H₂O₂; superoxide dismutase - SOD; reduced glutathione - GSH; oxidized glutathione - GSSG; and their ratio - GSH/GSSG) and inflammation (myeloperoxidase - MPO; interleukin (IL)-6; IL-8; IL-10; and tumor necrosis factor-alpha - TNF-α). All biomarkers were evaluated via linear regression with adjustments of variables with measures of weight, length, head circumference (HC), chest circumference (CC) and gestational age of newborns at birth, considering p < 0.05 as significant.

RESULTS

A total of 100 pregnant women with PE and 50 healthy pregnant women were studied. Higher placental levels of catalase (p = 0.018), SOD (p = 0.031), the GSH/GSSG ratio (p = 0.019) and IL-6 (p = 0.010) and lower GSSG (p = 0.001) were observed in pregnant women with PE than in the control group. Positive associations between placental GSH levels and body weight, HC, CC and gestational age at birth (p < 0.05) were identified.

CONCLUSION

PE-derived placentas had high concentrations of some antioxidants (enzymes and thiols), which might be a compensation mechanism against oxidative stress. Placental GSH levels were the only biomarker, among the studied ones, related positively with beneficial perinatal outcomes, suggesting that this endogenous antioxidant plays an important role in maintaining the health of the conceptus and women with PE.

Dysfunction of ABC transporters at the blood-brain barrier: Role in neurological disorders

ABC (ATP-binding cassette) transporters represent one of the largest and most diverse superfamily of proteins in living species, playing an important role in many biological processes such as cell homeostasis, cell signaling, drug metabolism and nutrient uptake. Moreover, using the energy generated from ATP hydrolysis, they mediate the efflux of endogenous and exogenous substrates from inside the cells, thereby reducing their intracellular accumulation. At present, 48 ABC transporters have been identified in humans, which were classified into 7 different subfamilies (A to G) according to their phylogenetic analysis. Nevertheless, the most studied members with importance in drug therapeutic efficacy and toxicity include P-glycoprotein (P-gp), a member of the ABCB subfamily, the multidrug-associated proteins (MPRs), members of the ABCC subfamily, and breast cancer resistance protein (BCRP), a member of the ABCG subfamily. They exhibit ubiquitous expression throughout the human body, with a special relevance in barrier tissues like the blood-brain barrier (BBB). At this level, they play a physiological function in tissue protection by reducing or limiting the brain accumulation of neurotoxins. Furthermore, dysfunction of ABC transporters, at expression and/or activity level, has been associated with many neurological diseases, including epilepsy, multiple sclerosis, Alzheimer's disease, and amyotrophic lateral sclerosis. Additionally, these transporters are strikingly associated with the pharmacoresistance to central nervous system (CNS) acting drugs, because they contribute to the decrease in drug bioavailability. This article reviews the signaling pathways that regulate the expression and activity of P-gp, BCRP and MRPs subfamilies of transporters, with particular attention at the BBB level, and their mis-regulation in neurological disorders.