Relevance of real-time analyzers to determine mitochondrial quality in endothelial cells and oxidative stress in preeclampsia

Oxidative stress and mitochondrial dysfunction are important elements for the pathophysiology of preeclampsia (PE), a multisystemic hypertensive syndrome of pregnancy, characterized by endothelial dysfunction and responsible for a large part of maternal and fetal morbidity and mortality worldwide. Researchers have dedicated their efforts to unraveling the intricate ways in which certain molecules influence both energy metabolism and oxidative stress. Exploring established methodologies from existing literature, shows that these investigations predominantly focus on the placenta, identified as a pivotal source that drives the changes observed in the disease. In this review, we discuss the role of oxidative stress in pathophysiology of PE, as well as metabolic/endothelial dysfunction. We further discuss the use of seahorse analyzers to study real-time bioenergetics of endothelial cells. Although the benefits are clear, few studies have presented results using this method to assess mitochondrial metabolism in these cells. We performed a search on MEDLINE/PubMed using the terms "Seahorse assay and endothelial dysfunction in HUVEC" as well as "Seahorse assay and preeclampsia". From our research, we selected 16 original peer-review papers for discussion. Notably, the first search retrieved studies involving Human Umbilical Vein Endothelial Cells (HUVECs) but none investigating bioenergetics in PE while the second search retrieved studies exploring the technique in PE but none of the studies used HUVECs. Additional studies are required to investigate real-time mitochondrial bioenergetics in PE. Clearly, there is a need for more complete studies to examine the nuances of mitochondrial bioenergetics, focusing on the contributions of HUVECs in the context of PE.

Plasma eNOS Concentration in Healthy Pregnancy and in Hypertensive Disorders of Pregnancy: Evidence of Reduced Concentrations in Pre-Eclampsia from Two Independent Studies

Hypertensive disorders of pregnancy (HDP), comprising gestational hypertension (GH) and pre-eclampsia (PE), are leading causes of maternal and perinatal morbidity and mortality. Both GH and PE are characterized by new-onset hypertension, but PE additionally includes proteinuria and/or end-organ damage. Impaired nitric oxide (NO) bioavailability may lead to endothelial dysfunction in GH and PE, and the primary source of vascular NO is endothelial NO synthase (eNOS). However, no previous study has investigated plasma eNOS concentrations in patients with GH and PE. In this study, we compared plasma eNOS concentrations in healthy pregnancies and HDP in two independent cohorts. The primary study included 417 subjects, with 43 non-pregnant (NP) and 156 healthy pregnant (HP) women and 122 patients with GH and 96 with PE. The replication study included 85 pregnant women (41 healthy and 44 pre-eclamptic). Plasma concentrations of eNOS were measured using a commercial ELISA kit provided by R&D Systems, and plasma nitrite concentrations were assessed using two ozone-based chemiluminescence assays. Correlations between plasma eNOS concentrations and plasma nitrite concentrations, as well as clinical and biochemical parameters, were evaluated by either Spearman's or Pearson's tests. In the primary study, NP women and HDP had significantly lower plasma eNOS concentrations compared to HP; concentrations were even lower in PE compared to GH. Plasma eNOS concentrations were reduced but not significant in early-onset PE, PE with severe features, preterm birth, and intrauterine growth restriction. No correlation was observed between plasma eNOS and nitrite levels. In HDP, there was a significant positive correlation between levels of eNOS and hemoglobin (r = 0.1496, p = 0.0336) as well as newborn weight (r = 0.1487, p = 0.0316). Conversely, a negative correlation between eNOS levels and proteinuria was observed (r = -0.2167, p = 0.0179). The replication study confirmed significantly reduced plasma concentrations of eNOS in PE compared to HP. Our findings provide evidence of reduced plasma eNOS concentrations in HDP; they were particularly lower in PE compared to GH and HP in two independent studies.

Longitudinal Study of Plasma Visfatin/Nicotinamide Phosphoribosyltransferase (NAMPT) Levels in Healthy Pregnant Women

Visfatin/nicotinamide phosphorybosil transferase (NAMPT) is a novel adipocytokine with potential roles in the pathophysiology of metabolic disorders, including gestational disorders. However, there is no clear interpretation regarding the circulating visfatin levels in a healthy pregnancy. Therefore, we conducted the first longitudinal study of plasma visfatin levels that followed up healthy pregnant women until the third trimester, including the postpartum period (PPP). The study recruited healthy women with singleton pregnancy who were not using any drug (including tobacco and alcohol). We have excluded pregnant women who did not attend all scheduled exams and developed gestational diabetes or hypertension, obesity, preeclampsia, or any infections during pregnancy. Nine women were considered eligible and examined during all three trimesters of pregnancy and between 8 and 12 weeks postpartum (PPP). Visfatin/NAMPT concentrations were measured in EDTA-plasma by ELISA. The mean age of pregnant women included was 22±5 years (54% primiparous), and the mean of gestational age at delivery was 40±1.2 weeks. Mean systolic and diastolic blood pressures were 90 and 70 mmHg, respectively. Mean values (± standard error mean) of visfatin concentrations (μg/L) during trimesters were 11.38±1.45 (first, 11-14 weeks), 9.18±1.82 (second, 20-24 weeks), 18.67±2.65 (third, 34-36 weeks), and 10.12±1.49 in the PPP. The value of the third trimester was significantly higher than the second trimester, and significantly reduced in the PPP (p<0.05, ANOVA with Bonferroni's multiple comparison tests). Visfatin/NAMPT levels are significantly lower in the PPP, suggesting that factors stimulating its production would be limited to pregnancy, thereby contributing to its potential application as a biomarker in pregnancy complications.

Circulating levels of tissue inhibitor of metalloproteinase 3, a protein with inhibitory effects on angiogenesis, are increased in pre-eclampsia

OBJECTIVE

To assess and compare circulating tissue inhibitor of metalloproteinase 3 (TIMP-3) concentrations between women with pre-eclampsia and healthy pregnant women. We also aimed to determine the relationships between circulating TIMP-3 and matrix metalloproteinase 2 (MMP-2), MMP-9, TIMP-1, and TIMP-2 concentrations in pre-eclampsia.

METHODS

A primary case-control study included patients with pre-eclampsia (n = 219) and gestational hypertension (n = 118), healthy pregnant women (n = 214), and non-pregnant women (n = 66), and a replication case-control study included patients with pre-eclampsia (n = 177) and healthy pregnant women (n = 124), all from southeastern Brazil. Plasma TIMP-3, MMP-2, MMP-9, TIMP-1, and TIMP-2 concentrations were assessed using commercially available enzyme-linked immunosorbent assay kits, and the relationships between them were analyzed using Spearman's correlation.

RESULTS

In our primary study, patients with pre-eclampsia and gestational hypertension exhibited increased TIMP-3 concentrations compared with healthy pregnant women (both P < 0.0001) and non-pregnant women (both P < 0.001). These findings were confirmed in the replication study, showing elevated TIMP-3 concentrations in women with pre-eclampsia versus healthy pregnant women (P < 0.001). We found no difference in TIMP-3 concentrations between early-onset and late-onset pre-eclampsia. Moreover, TIMP-3 concentrations were significantly correlated with plasma concentrations of TIMP-1 (r = 0.2333; P = 0.0086) and MMP-2 (r = 0.2159; P = 0.0156) in pre-eclampsia.

CONCLUSIONS

Circulating TIMP-3 concentration is increased in women with pre-eclampsia compared with healthy pregnant women, and it is positively correlated with plasma MMP-2 and TIMP-1 concentrations in pre-eclampsia.

Vitamin D decreases expression of NLRP1 and NLRP3 ninflammasomes in placental explants from women with preeclampsia cultured with hydrogen peroxide

This study aimed to evaluate the immunomodulatory effect of vitamin D (VD) on the NLRP1 and NLRP3 inflammasomes in placental explants from preeclamptic (PE) and normotensive (NT) pregnant women. Placental explants from eight PE and eight NT pregnant women were cultured with or without hydrogen peroxide (H₂O₂)_, VD or H₂O₂ + VD. Gene and protein expression of NLRP1, NLRP3, HMGB1, caspase-1, IL-1β, TNF-α and IL-18 were determined by qPCR and Western blotting/ELISA. Compared to NT pregnant women, the endogenous gene expression of NLRP1, NLRP3, HMGB1, IL-1β, TNF-α and IL-18 was significantly higher in explants from PE and became decreased after VD treatment. Similarly, VD decreased the protein expression of NLRP1, NLRP3, caspase-1, HMGB1, IL-1β, TNF-α and IL-18 in PE. Placental explants from NT cultured with H₂O₂ showed increased gene and protein expression of NLRP1, NLRP3, caspase-1, IL-1β, TNF-α and HMGB1, while H₂O₂ was also able to increase TNF-α and caspase-1 gene expression in PE. Treatment with H₂O₂ + VD decreased gene/protein expression of NLRP1, NLRP3, caspase-1, HMGB1, IL-1β, TNF-α and IL-18 in PE and NT explants with H₂O₂. NLRP1 and NLRP3 are upregulated in the PE. VD may play an immunomodulatory role in the placental inflammation and downregulates oxidative stress induced in vitro by H₂O_2.

Effects of vitamin D-induced supernatant of placental explants from preeclamptic women on oxidative stress and nitric oxide bioavailability in human umbilical vein endothelial cells

The study evaluated the effect of the supernatant of placental explants from preeclamptic (PE) and normotensive (NT) pregnant women after tissue treatment with or without vitamin D (VD) on oxidative stress and nitric oxide (NO) bioavailability in human umbilical vein endothelial cells (HUVEC). Placental explants were prepared from eight NT and eight PE women, and supernatants were obtained after incubation with or without hydrogen peroxide (H₂O₂) and/or VD. HUVEC were cultured for 24 h with supernatants, and the following parameters were analyzed in HUVEC cultures: NO, nitrate (NO₃^-), and nitrite (NO₂^-) levels, lipid peroxidation, and intracellular reactive oxygen species (ROS). Results showed that the production of NO₃^-, NO₂^-, malondialdehyde (MDA), and ROS were significantly higher in HUVEC treated with explant supernatant from PE compared to NT pregnant women, while the supernatant of PE explants treated with VD led to a decrease in these parameters. A significantly high production of NO was detected in HUVEC cultured with control supernatant of NT group, and in cultures treated with supernatant of PE explants treated with VD. Taken together, these results demonstrated that cultures of placental explants from PE women with VD treatment generated a supernatant that decreased oxidative stress and increased the bioavailability of NO in endothelial cells.

Association between cytokine profile and transcription factors produced by T-cell subsets in early- and late-onset pre-eclampsia

Pre-eclampsia (PE) is an obstetric pathology characterized by abnormal activation of the innate and adaptive immune systems dependent on the imbalance of T helper subsets. The present study aimed to evaluate the gene and protein expression of T helper type 1 (Th1)/Th2/Th17/regulatory T (Treg) cell transcription factors in peripheral blood lymphocytes from pregnant women with PE employing quantitative RT-PCR and flow cytometry techniques, as well as the cytokine profile produced by these CD4+ T-cell subsets in the plasma of pregnant women with PE, classified as early-onset PE (n = 20), late-onset PE (n = 20) and normotensive pregnant women (n = 20). Results showed a higher percentage of CD4+ T cells expressing the RORc transcription factor (Th17) and a lower percentage of cells expressing FoxP3 (Treg) in women with early-onset PE compared with late-onset PE and normotensive groups. A lower gene expression of GATA-3 transcription factor was detected in cells of women with early-onset PE compared with the late-onset PE group. Endogenous plasma levels of interleukin-6 (IL-6), IL-17 and tumour necrosis factor-α were significantly higher in the early-onset PE group than in the late-onset PE and normotensive groups, whereas IL-4 (Th2 profile) and IL-22 (Th17 profile), were not significantly different between the studied groups. The endogenous levels of transforming growth factor-β and IL-10 were significantly lower in the pre-eclamptic than in the normotensive groups of the same gestational age, with a significant difference between early- and late-onset PE. The results show that in women with PE there is an imbalance between inflammatory and anti-inflammatory profiles in CD4+ T-cell subsets, with polarization to Th17 profiles in the early-onset PE, considered as the severe form of PE.