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BACKGROUND: Preeclampsia is a serious condition of pregnancy, complicated by aberrant maternal vascular dysfunction. CNP (C-type natriuretic peptide) contributes to vascular homeostasis, acting through NPR-B (natriuretic peptide receptor-B) and NPR-C (natriuretic peptide receptor-C). CNP mitigates vascular dysfunction of arteries in nonpregnant cohorts; this study investigates whether CNP can dilate maternal arteries in ex vivo preeclampsia models. METHODS: Human omental arteries were dissected from fat biopsies collected during cesarean section. CNP, NPR-B, and NPR-C mRNA expression was assessed in arteries collected from pregnancies complicated by preeclampsia (n=6) and normotensive controls (n=11). Using wire myography, we investigated the effects of CNP on dilation of arteries from normotensive pregnancies. Arteries were preconstricted with either serum from patients with preeclampsia (n=6) or recombinant ET-1 (endothelin-1; vasoconstrictor elevated in preeclampsia; n=6) to model vasoconstriction associated with preeclampsia. Preconstricted arteries were treated with recombinant CNP (0.001-100 µmol/L) or vehicle and vascular relaxation assessed. In further studies, arteries were preincubated with NPR-B (5 µmol/L) and NPR-C (10 µmol/L) antagonists before serum-induced constriction (n=4-5) to explore mechanistic signaling. RESULTS: CNP, NPR-B, and NPR-C mRNAs were not differentially expressed in omental arteries from preeclamptic pregnancies. CNP potently stimulated maternal artery vasorelaxation in our model of preeclampsia (using preeclamptic serum). Its vasodilatory actions were driven through the activation of NPR-B predominantly; antagonism of this receptor alone dampened CNP vasorelaxation. Interestingly, CNP did not reduce ET-1--driven omental artery constriction. CONCLUSIONS: Collectively, these data suggest that enhancing CNP signaling through NPR-B offers a potential therapeutic strategy to reduce systemic vascular constriction in preeclampsia. [ABSTRACT FROM AUTHOR]

Preeclampsia is a hypertensive disorder of pregnancy characterized by maternal endothelial dysfunction and end-organ damage. The antiangiogenic factor, sFlt-1 (soluble FMS-like tyrosine kinase-1) has been strongly implicated in the pathogenesis of preeclampsia. sFlt-1 is secreted into the maternal circulation where it antagonizes VEGF (vascular endothelial growth factor) and ultimately disrupts vascular homeostasis. However, the upstream mechanisms regulating release of sFlt-1 are poorly characterized. We investigated the roles of key prosurvival pathways, EGFR (epidermal growth factor receptor) signaling, and the mitochondria, in regulating sFlt-1 production. We initially found that the mRNA and protein of EGFR and downstream adaptor molecules were significantly increased in preeclamptic placental tissue relative to normotensive controls. Inhibiting the EGFR signaling cascade using siRNA (small interfering ribonucleic acid) or small molecule inhibitors significantly reduced sFlt-1 release from primary cytotrophoblast (placental cells). Additionally, inhibiting the mitochondrial electron transport chain or activating downstream energy-sensing molecules (AMPK [AMP-activated kinase], SIRT1 [sirtuin 1 ], and PGC1α [PPAR-γ co-activator 1]) also significantly reduced sFlt-1 secretion from cytotrophoblast cells, without affecting EGFR signaling. In vivo, treating pregnant mice with gefitinib (an EGFR inhibitor) or resveratrol (perturbs mitochondrial function) significantly reduced circulating murine sFlt-1 compared with vehicle control. Furthermore, treating primary cytotrophoblasts with therapeutics which have been previously found to reduce sFlt-1 secretion, either reduced EGFR signaling (esomeprazole and statins) or perturbed mitochondrial function (esomeprazole, resveratrol, and metformin). Additionally, targeting both pathways simultaneously produced additive reductions in sFlt-1 secretion. Thus, we have identified 2 key survival pathways that seem to be overactive in preeclampsia and involved in the regulation of placental sFlt-1 secretion. [ABSTRACT FROM AUTHOR]

Preeclampsia is a major pregnancy complication associated with poor placental perfusion and placental hypoxia. Systemic and placental inflammation and elevated placental secretion of the antiangiogenic factors sFlt-1 (soluble fms-like tyrosine kinase 1) and sEng (soluble endoglin) are hallmarks of preeclampsia, causing endothelial dysfunction and multiorgan injury. A molecule that links placental hypoxia, inflammation, and antiangiogenic factor release has not been described. ATF3 (activating transcription factor 3) is highly expressed in placenta. We assessed whether placental ATF3 is dysregulated in preterm preeclampsia, is altered by hypoxia, and regulates proinflammatory cytokine and antiangiogenic factor production. ATF3 mRNA and protein expression was significantly reduced in preterm preeclamptic placentas compared with gestation-matched controls. Hypoxia reduced ATF3 expression in primary cytotrophoblast and placental explants. Silencing ATF3 in primary cytotrophoblast increased proinflammatory cytokine (IL-6 [interleukin 6], TNF-α [tumor necrosis factor α]) and NF-κB (nuclear factor κB) expression. In silico analysis identified an ATF3-binding site in the promoter of Flt-1 (the transcript from which sFlt-1 is produced). Silencing ATF3 increased sFlt-1 and sEng secretion from primary cytotrophoblast possibly by increasing Rab11a and Arf1, cargo proteins that facilitate exosomal release of sFlt-1. ATF3 knockout mice did not have a preeclampsia phenotype, suggesting that these pathways may be specific to humans (preeclampsia is a uniquely human condition). To conclude, we have shown that ATF3 is decreased in preeclamptic placentas and that this decrease is likely to occur after prolonged hypoxia. We show that ATF3 is a regulator of placental proinflammatory cytokines and antiangiogenic factors sFlt-1 and sEng. Therefore, reduced ATF3 may be centrally involved in the pathology of preeclampsia. [ABSTRACT FROM AUTHOR]

Preeclampsia is a severe complication of pregnancy. Antiangiogenic factors soluble fms-like tyrosine kinase-1 (sFlt-1) and soluble endoglin are secreted in excess from the placenta, causing hypertension, endothelial dysfunction, and multiorgan injury. Oxidative stress and vascular inflammation exacerbate the endothelial injury. A drug that can block these pathophysiological steps would be an attractive treatment option. Proton pump inhibitors (PPIs) are safe in pregnancy where they are prescribed for gastric reflux. We performed functional studies on primary human tissues and animal models to examine the effects of PPIs on sFlt-1 and soluble endoglin secretion, vessel dilatation, blood pressure, and endothelial dysfunction. PPIs decreased sFlt-1 and soluble endoglin secretion from trophoblast, placental explants from preeclamptic pregnancies, and endothelial cells. They also mitigated tumor necrosis factor-α-induced endothelial dysfunction: PPIs blocked endothelial vascular cell adhesion molecule-1 expression, leukocyte adhesion to endothelium, and disruption of endothelial tube formation. PPIs decreased endothelin-1 secretion and enhanced endothelial cell migration. Interestingly, the PPI esomeprazole vasodilated maternal blood vessels from normal pregnancies and cases of preterm preeclampsia, but its vasodilatory effects were lost when the vessels were denuded of their endothelium. Esomeprazole decreased blood pressure in a transgenic mouse model where human sFlt-1 was overexpressed in placenta. PPIs upregulated endogenous antioxidant defenses and decreased cytokine secretion from placental tissue and endothelial cells. We have found that PPIs decrease sFlt-1 and soluble endoglin secretion and endothelial dysfunction, dilate blood vessels, decrease blood pressure, and have antioxidant and anti-inflammatory properties. They have therapeutic potential for preeclampsia and other diseases where endothelial dysfunction is involved. [ABSTRACT FROM AUTHOR]

In preeclampsia, the antiangiogenic factor soluble fms-like tyrosine kinase-1 (sFLT-1) is released from placenta into the maternal circulation, causing endothelial dysfunction and organ injury. A recently described splice variant, sFLT-1 e15a, is primate specific and the most abundant placentally derived sFLT-1. Therefore, it may be the major sFLT-1 isoform contributing to the pathophysiology of preeclampsia. sFLT-1 e15a protein remains poorly characterized: its bioactivity has not been comprehensively examined, and serum levels in normal and preeclamptic pregnancy have not been reported. We generated and validated an sFLT-1 e15a-specific ELISA to further characterize serum levels during pregnancy, and in the presence of preeclampsia. Furthermore, we performed assays to examine the bioactivity and antiangiogenic properties of sFLT-1 e15a protein. sFLT-1 e15a was expressed in the syncytiotrophoblast, and serum levels rose across pregnancy. Strikingly, serum levels were increased 10-fold in preterm preeclampsia compared with normotensive controls. We confirmed sFLT-1 e15a is bioactive and is able to inhibit vascular endothelial growth factor signaling of vascular endothelial growth factor receptor 2 and block downstream Akt phosphorylation. Furthermore, sFLT-1 e15a has antiangiogenic properties. sFLT-1 e15a decreased endothelial cell migration, invasion, and inhibited endothelial cell tube formation. Administering sFLT-1 e15a blocked vascular endothelial growth factor induced sprouts from mouse aortic rings ex vivo. We have demonstrated that sFLT-1 e15a is increased in preeclampsia, antagonizes vascular endothelial growth factor signaling, and has antiangiogenic activity. Future development of diagnostics and therapeutics for preeclampsia should consider targeting placentally derived sFLT-1 e15a. [ABSTRACT FROM AUTHOR]

Elevated placental release of the antiangiogenic factors, soluble fms-like tyrosine kinase-1 (sFlt-1) and soluble endoglin (sENG), is central to the pathophysiology of preeclampsia. It is widely accepted that heme oxygenase-1 (HO-1) is decreased in preeclamptic placenta and negatively regulates sFlt-1 and sENG production. We set out to verify these contentions. There was no difference in HO-1 mRNA or protein levels in preterm preeclamptic placentas (n=17) compared with gestationally matched controls (n=27). In silico analysis of microarray studies did not identify decreased placental HO-1 expression in preeclamptic placenta. Silencing HO-1 in primary trophoblasts did not affect sFlt-1 protein secretion after 24 or 48 hours. Silencing nuclear factor (erythroid-derived 2)-like 2 (transcription factor that upregulates HO-1) in trophoblasts also did not affect sFlt-1 secretion. Administering tin protoporphyrin IX dichloride (HO-1 inhibitor) or cobalt protoporphyrin (HO-1 inducer) into placental explants did not affect sFlt-1 or sENG secretion. Silencing HO-1 in 2 types of primary endothelial cells (human umbilical vein endothelial and uterine microvascular endothelial cells) significantly increased sFlt-1 secretion but not sENG secretion. However, HO-1 silencing selectively increased mRNA expression of sFlt-1 i13 (generically expressed sFlt-1 variant) but not of sFlt-1 e15a (sFlt-1 variant mainly expressed in placenta). Furthermore, adding tin protoporphyrin IX dichloride decreased sFlt-1, whereas adding HO-1 inducers (cobalt protoporphyrin, dimethyl fumarate, and rosiglitazone) either had no effect or increased sFlt-1 or sENG secretion (these trends are opposite to what is expected). We conclude that HO-1 expression is not decreased in preeclamptic placenta and HO-1 does not negatively regulate placental sFlt-1 and sENG secretion in placental or endothelial cells. [ABSTRACT FROM AUTHOR]

Preeclampsia is a major pregnancy complication where excess placental release of soluble fms-like tyrosine kinase-1 (sFlt-1) and soluble endoglin causes maternal endothelial and multisystem organ injury. Clinical trials have commenced examining whether pravastatin can be used to treat preeclampsia. However, the preclinical evidence supporting pravastatin as a treatment is limited to animal models, with almost no studies in human tissues. Therefore, we examined whether pravastatin reduced sFlt-1 and soluble endoglin secretion and decreased endothelial dysfunction in primary human tissues. Pravastatin reduced sFlt-1 secretion from primary endothelial cells, purified cytotrophoblast cells, and placental explants obtained from women with preterm preeclampsia. It increased soluble endoglin secretion from endothelial cells but did not change secretion from placental explants. The regulation of sFlt-1 by pravastatin seemed to be mediated via the 3-hydroxy-3-methylglutaryl-coenzyme A reductase cholesterol synthesis pathway. Pravastatin also reduced markers of endothelial dysfunction, including vascular cell adhesion molecule-1 expression and leukocyte adhesion on endothelial cells and increased endothelial cell migration and invasion. We also treated 4 patients with preterm preeclampsia presenting at <30 weeks of gestation with daily pravastatin. Pravastatin seemed to stabilize blood pressure, proteinuria, and serum uric acid levels. Furthermore, serum sFlt-1 levels decreased. We collected the placentas at delivery and found that pravastatin reduced sFlt-1 secretion. These results indicate that pravastatin reduced sFlt-1 and soluble endoglin production and decreased endothelial dysfunction in primary human tissues. We also present pilot data, suggesting that pravastatin can stabilize clinical and biochemical features of preterm preeclampsia. Our data obtained in human tissues support the concept that pravastatin is a candidate therapeutic for preeclampsia. [ABSTRACT FROM AUTHOR]

Preeclampsia is a severe complication of pregnancy, characterized by hypertension, oxidative stress, and severe endothelial dysfunction. Antiangiogenic factors, soluble fms-like tyrosine kinase-1 (sFlt-1) and soluble endoglin, play key pathophysiological roles in preeclampsia. Heme oxygenase-1 (HO-1) is a cytoprotective, antioxidant enzyme reported to be downregulated in preeclampsia. Studies propose that inducing HO-1 may also decrease sFlt-1 production. Sofalcone, a gastric antiulcer agent in clinical use, is known to induce HO-1 in gastric epithelium. We aimed to investigate whether sofalcone induces HO-1 and reduces sFlt-1 release from primary human placental and endothelial cells and blocks endothelial dysfunction in vitro. We isolated human trophoblasts and endothelial cells (human umbilical vein endothelial cells) and also used uterine microvascular cells. We investigated the effects of sofalcone on (1) HO-1 production, (2) activation of the nuclear factor (erythroid-derived 2)-like 2 pathway, (3) sFlt-1 and soluble endoglin release, (4) tumor necrosis factor α-induced monocyte adhesion and vascular cell adhesion molecule upregulation, and (5) endothelial tubule formation. Sofalcone potently increased HO-1 mRNA and protein in both primary trophoblasts and human umbilical vein endothelial cells. Furthermore, sofalcone treatment caused nuclear translocation of nuclear factor (erythroid-derived 2)-like 2 and transactivation of other nuclear factor (erythroid-derived 2)-like 2 responsive genes (NQO1, TXN, and GCLC). Importantly, sofalcone significantly decreased the secretion of sFlt-1 from primary human trophoblasts. Sofalcone potently suppressed endothelial dysfunction in 2 in vitro models, blocking tumor necrosis factor α-induced monocyte adhesion and vascular cell adhesion molecule 1 expression in human umbilical vein endothelial cells. These results indicate that in primary human tissues, sofalcone can potently activate antioxidant nuclear factor (erythroid-derived 2)-like 2/HO-1 pathway, decrease sFlt-1 production, and ameliorate endothelial dysfunction. We propose that sofalcone is a novel therapeutic candidate for preeclampsia. [ABSTRACT FROM AUTHOR]

Preeclampsia is a severe complication of pregnancy, characterized by hypertension, oxidative stress, and severe endothelial dysfunction. Antiangiogenic factors, soluble fms-like tyrosine kinase-1 (sFlt-1) and soluble endoglin, play key pathophysiological roles in preeclampsia. Heme oxygenase-1 (HO-1) is a cytoprotective, antioxidant enzyme reported to be downregulated in preeclampsia. Studies propose that inducing HO-1 may also decrease sFlt-1 production. Sofalcone, a gastric antiulcer agent in clinical use, is known to induce HO-1 in gastric epithelium. We aimed to investigate whether sofalcone induces HO-1 and reduces sFlt-1 release from primary human placental and endothelial cells and blocks endothelial dysfunction in vitro. We isolated human trophoblasts and endothelial cells (human umbilical vein endothelial cells) and also used uterine microvascular cells. We investigated the effects of sofalcone on (1) HO-1 production, (2) activation of the nuclear factor (erythroid-derived 2)-like 2 pathway, (3) sFlt-1 and soluble endoglin release, (4) tumor necrosis factor α-induced monocyte adhesion and vascular cell adhesion molecule upregulation, and (5) endothelial tubule formation. Sofalcone potently increased HO-1 mRNA and protein in both primary trophoblasts and human umbilical vein endothelial cells. Furthermore, sofalcone treatment caused nuclear translocation of nuclear factor (erythroid-derived 2)-like 2 and transactivation of other nuclear factor (erythroid-derived 2)-like 2 responsive genes (NQO1, TXN, and GCLC). Importantly, sofalcone significantly decreased the secretion of sFlt-1 from primary human trophoblasts. Sofalcone potently suppressed endothelial dysfunction in 2 in vitro models, blocking tumor necrosis factor α-induced monocyte adhesion and vascular cell adhesion molecule 1 expression in human umbilical vein endothelial cells. These results indicate that in primary human tissues, sofalcone can potently activate antioxidant nuclear factor (erythroid-derived 2)-like 2/HO-1 pathway, decrease sFlt-1 production, and ameliorate endothelial dysfunction. We propose that sofalcone is a novel therapeutic candidate for preeclampsia. [ABSTRACT FROM AUTHOR]