The immunohistochemical evaluation of VEGF in placenta biopsies of pregnancies complicated by preeclampsia

FtMt reduces oxidative stress-induced trophoblast cell dysfunction via the HIF-1α/VEGF signaling pathway

BACKGROUND

Preeclampsia (PE) is a complication of pregnancy that causes long-term adverse outcomes for the mother and fetus and may even lead to death. Oxidative stress caused by the imbalance of oxidants and antioxidants in the placenta has been considered as one of the key mechanisms of preeclampsia (together with inflammation, etc.), in which the placental mitochondria play an important role. The expression of hypoxia-inducible factor-1 (HIF-1α) and vascular endothelial growth factor (VEGF) is known to be increased in patients with PE. Mitochondrial ferritin (FtMt) is known to protect the mitochondria from oxidative stress, although its specific role in PE remains unclear.

METHODS

We used qRT-PCR and western blotting to detect the expression levels of FtMt, HIF-1α, and VEGF in placental tissues from patients with PE. Human chorionic trophoblast cells were also administered with hypoxia treatment, followed by the detection of cell proliferation, invasion and angiogenic capacity by CCK8, Transwell, and endothelial cell angiogenesis assays; we also detected the expression of HIF-1α and VEGF in these cells. Finally, overexpression or inhibitory FtMt lentiviral vectors, along with negative control vectors, were constructed and transfected into hypoxia-treated human chorionic trophoblast cells; this was followed by analyses of cell function.

RESULTS

The expression levels of FtMt, HIF-1α and VEGF in the PE group were higher than those in the control group (P < 0.05). Following hypoxia, there was an increase in the expression levels of HIF-1α and VEGF protein in trophoblast cells. There was also an increase in invasion ability and vascular formation ability along with a reduction in cell proliferation ability. These effects were reversed by transfecting cells with the knockout FtMt lentivirus vector. The differences were statistically significant.

CONCLUSION

Analyses showed that FtMt plays a key role in the vascular regulation of PE trophoblast cells after hypoxia possibly acting via the HIF-1α/VEGF signaling pathway. These results provide us an enhanced understanding of the pathogenesis of PE and suggest that the HIF-1α/VEGF signaling pathway represents a new target for the treatment of PE.

Quantification of Protein Expression by Proximity Ligation Assay in the Nonhuman Primate in Response to Estrogen

In the field of protein biology, immunology-based techniques are continuously evolving for the detection and quantification of individual protein levels, protein-protein interaction, and protein modifications in cells and tissues. The proximity ligation assay (PLA), a method of detection that combines immunologic and PCR-based approaches, was developed to overcome some of the drawbacks that are inherent with other detection methods. The PLA allows for very sensitive and discretely quantifiable measures of unmodified, native protein levels and protein-protein interaction/modification complexes in situ in both fixed tissues and cultured cells. We describe herein the PLA method and its applicability to quantify the effects of estrogen on expression of angioregulatory factors, e.g., endothelial nitric oxide synthase (eNOS) in the vasculature, vascular endothelial growth factor (VEGF) in the placenta, and melanocortin 2 receptor (MC2R)/accessory protein (MRAP) in the fetal adrenal of the nonhuman primate.

Prenatal vitamin D supplementation reduces blood pressure and improves placental angiogenesis in an animal model of preeclampsia

BACKGROUND

Preeclampsia (PE), a pregnancy complication, is characterized by abnormal placental angiogenesis. The current study examines the effect of vitamin D deficiency/supplementation on pregnancy outcome and placental angiogenesis using an animal model of PE.

METHODS

Pregnant Wistar rats were divided into four groups: Control; PE; Vitamin D deficient with PE (VDD-PE) and Vitamin D supplemented with PE (VDS-PE). PE was induced by administering l-nitroarginine methyl ester (l-NAME) at the dose of 50 mg per kg body weight per day from day 14 to day 19 gestation in all the 4 groups. During the pre-pregnancy and pregnancy period, the rats from the Control and PE groups were fed a control diet, the VDD-PE group received a vitamin D deficient diet and the VDS-PE group received a vitamin D supplemented diet. Dams were sacrificed at d20 of gestation.

RESULTS

l-NAME administration increased systolic as well as diastolic blood pressure in both PE and VDD-PE groups as compared to the control (p < 0.01). Vitamin D supplementation was beneficial in reducing the blood pressure. Vitamin D deficiency also lowered the placental protein levels of pro-angiogenic proteins VEGF and Flt-1 (p < 0.05 and p < 0.01, respectively), while the levels of these proteins in the VDS-PE group were similar to those in the control group. Vitamin D status did not influence the levels of PlGF and Hif1α.

CONCLUSION

A low dose vitamin D supplementation given from pre-pregnancy and throughout pregnancy was beneficial in reducing the blood pressure and normalizing the placental levels of VEGF and Flt-1. This has implications for reducing the severity of preeclampsia.

An Insight into the Angiogenic and Lymphatic Interplay in Pre-eclampsia Comorbid with HIV Infection

PURPOSE OF REVIEW

To provide insight on the imbalance of angiogenic and lymphangiogenic factors in pre-eclampsia, as well as highlight polymorphism in genes related to angiogenesis and lymphangiogenesis.

RECENT FINDINGS

The pregnancy-specific disorder pre-eclampsia is diagnosed by the presence of hypertension with/without proteinuria, after 20 weeks of gestation. The pathogenesis of pre-eclampsia remains ambiguous, but research over the years has identified an imbalance in maternal and foetal factors. Familial predisposition and gene variation are also linked to pre-eclampsia development. The sFlt-1/PIGF ratio has attracted great attention over the years; more recently several researchers have reported that a sFlt-1/PIGF ratio of ≤ 38 can be used to predict short-term absence of pre-eclampsia. This ratio has the potential to prevent adverse pregnancy outcomes and reduce healthcare costs significantly. Genome-wide studies have additionally identified variation in the foetal gene near Flt-1. The development of preeclampsia is not limited to the maternal interface, but foetal involvement as well as genetic interplay is associated with the disorder.

Maternal omega-3 fatty acids and vitamin E improve placental angiogenesis in late-onset but not early-onset preeclampsia

Abnormal placental vasculature is associated with preeclampsia. Preeclampsia is of two types, i.e., early- and late-onset preeclampsia (LOP), both having different etiologies. We have earlier demonstrated low levels of omega-3 fatty acids and vitamin E in women with preeclampsia. The current study examines the effect of maternal omega-3 fatty acids and vitamin E supplementation on angiogenic factors in a rat model of preeclampsia. Pregnant rats were divided into a total of five groups control, early-onset preeclampsia (EOP); LOP; EOP supplemented with omega-3 fatty acid and vitamin E and LOP supplemented with omega-3 fatty acid and vitamin E. Preeclampsia was induced by administering L-nitroarginine methylester (L-NAME) at the dose of 50 mg/kg body weight/day. The vascular endothelial growth factor gene expression and protein levels were lower (p < 0.01 for both) in animals from both EOP as well as LOP groups (p < 0.01). In the EOP group, the protein levels of VEGF receptor-1 were also lower (p < 0.01). Supplementation of omega-3 fatty acids and vitamin E to LOP improved the levels of VEGF and VEGF receptor-1 only in the LOP but not in the EOP group. In the EOP group, the gene expression of hypoxia inducible factor 1 alpha (HIF-1α) in the placenta was higher (p < 0.05) and supplementation normalized these levels. Our findings indicate that maternal supplementation of omega-3 fatty acids and vitamin E has differential effect on preeclampsia subtypes.

Placental growth factor, vascular endothelial growth factor, and hypoxia-inducible factor-1α in the placentas of women with pre-eclampsia

BACKGROUND

Although the exact mechanism of pre-eclampsia - high blood pressure and proteinuria after 20 gestational weeks - is not yet fully understood, placental growth factor (PLGF), vascular endothelial growth factor (VEGF), and hypoxia-inducible factor (HIF) are known to play important roles in vascularization and in the pathology of pre-eclampsia.

METHODS

PLGF, VEGF, and HIF-1α were evaluated by immunohistochemistry in the placentas of Sudanese women with mild or severe pre-eclampsia, and in normal controls.

RESULTS

Sixty-two women had severe pre-eclampsia, 102 had mild pre-eclampsia and 101 women served as healthy controls. Immunohistochemical staining of PLGF was significantly lower in placentas of women with severe pre-eclampsia (16%) compared with those with mild pre-eclampsia (8.8%) and placentas of normotensive women (40.6%; p < .001). Significantly more of the pre-eclamptic placentas expressed VEGF: in 32%, 17.6%, and 14.9% (p = .020) of the placentas of women with severe or mild pre-eclampsia and in controls, respectively. Significantly more of the pre-eclamptic placentas expressed HIF-1α: in 15%, 10.8%, and 5.0% of the placentas of women with severe or mild pre-eclampsia, and in controls, respectively (p = .044).

CONCLUSION

The current study showed that PLGF, VEGF, and HIF-1α are involved in the pathophysiology of pre-eclampsia.

VEGF may contribute to macrophage recruitment and M2 polarization in the decidua

It is increasingly evident that cytokines and growth factors produced in the decidua play a pivotal role in the regulation of the local immune microenvironment and the establishment of pregnancy. One of the major growth factors produced in the decidua is vascular endothelial growth factor (VEGF), which acts not only on endothelial cells, but also on multiple other cell types, including macrophages. We sought to determine whether decidua-derived VEGF affects macrophage recruitment and polarization using human endometrial/decidual tissue samples, primary human endometrial stromal cells (ESCs), and the human monocyte cell line THP1. In situ hybridization was used for assessment of local VEGF expression and immunohistochemistry was used for identification and localization of CD68-positive endometrial macrophages. Macrophage migration in culture was assessed using a transwell migration assay, and the various M1/M2 phenotypic markers and VEGF expression were assessed using quantitative real-time PCR (qRT-PCR). We found dramatic increases in both VEGF levels and macrophage numbers in the decidua during early pregnancy compared to the secretory phase endometrium (non-pregnant), with a significant increase in M2 macrophage markers, suggesting that M2 is the predominant macrophage phenotype in the decidua. However, decidual samples from preeclamptic pregnancies showed a significant shift in macrophage phenotype markers, with upregulation of M1 and downregulation of M2 markers. In THP1 cultures, VEGF treatment significantly enhanced macrophage migration and induced M1 macrophages to shift to an M2 phenotype. Moreover, treatment with conditioned media from decidualized ESCs induced changes in macrophage migration and polarization similar to that of VEGF treatment. These effects were abrogated by the addition of a potent VEGF inhibitor. Together these results suggest that decidual VEGF plays a significant role in macrophage recruitment and M2 polarization, and that inhibition of VEGF signaling may contribute to the shift in macrophage polarity observed in different pregnancy disorders, including preeclampsia.

Micro- and Nano-vesicles from First Trimester Human Placentae Carry Flt-1 and Levels Are Increased in Severe Preeclampsia

BACKGROUND/OBJECTIVES

Preeclampsia is a life-threatening hypertensive disease affecting 3-5% of pregnancies. While the pathogenesis of preeclampsia remains unclear, it is known that placenta-derived factors trigger the disease by activating maternal endothelial cells prior to the onset of clinical symptoms. Extracellular vesicles (EVs) of different sizes extruded by the placenta may be one factor. The truncated/secreted form of Flt-1 (sFlt-1) has also been implicated in the pathogenesis of preeclampsia. We investigated whether placental EV production is altered in preeclampsia such that they induce endothelial cell activation, and whether (s)Flt-1 is involved.

METHODS

Macro-, micro-, and nano-vesicles were collected from normal and preeclamptic (PE) placental explants, and separated by differential centrifugation. The number and size of micro- and nano-vesicles was measured by nanoparticle tracking analysis and their ability to activate endothelial cells was quantified by endothelial cell intercellular adhesion molecule 1 expression and monocyte adhesion. The levels of Flt-1 were measured by western blots and ELISA.

RESULTS

PE placentae extruded significantly more micro- and nano-vesicles than control placentae and the extruded micro-vesicles were larger than those from control placentae. Micro- and nano-vesicles from both first trimester and term human placentae carried Flt-1 and levels were significantly increased in EVs from severe, but not mild, PE compared to normotensive placentae. All fractions of EVs from PE placentae activated endothelial cells, and for micro- and nano-vesicles, activation was reduced in the presence of exogenous vascular endothelial growth factor (VEGF), a Flt-1 neutralizing antibody, or by pre-treatment with VEGF. While EV-bound VEGF constituted over 20% of the total detected VEGF secreted by PE and normotensive placentae, EV-bound Flt-1 did not significantly contribute to the total level of sFlt-1/Flt-1 released by human third trimester placentae.

DISCUSSION

Micro- and nano-vesicles extruded by human placentae carry Flt-1 across gestation and in severe preeclampsia, the levels of vesicle-bound Flt-1 are upregulated. All fractions of PE placental EVs activated endothelial cells and for micro- and nano-vesicles, this was in part due to the ability of EV-bound Flt-1 to sequester VEGF. That placental EVs can activate endothelial cells supports the contention that EVs are one placental toxin contributing to the pathogenesis of preeclampsia.

Assessment of Protein Expression by Proximity Ligation Assay in the Nonhuman Primate Endometrium, Placenta, and Fetal Adrenal in Response to Estrogen

In the field of protein biology, immunology-based techniques have been evolving for detection and quantification of protein levels, protein-protein interaction, and protein modifications in cells and tissues. The proximity ligation assay (PLA), a method of detection that combines immunologic and PCR-based approaches, was developed to overcome some of the drawbacks that are inherent to other detection methods. The PLA allows for very sensitive and discretely quantifiable measures of unmodified, native protein levels, and protein-protein interaction/modification complexes in situ in both fixed tissues and cultured cells. We describe herein the PLA method and its applicability to quantify the effects of estrogen on expression of angioregulatory factors, e.g., angiopoietin-1 (Ang-1) in the endometrium, vascular endothelial growth factor (VEGF) in the placenta, and melanocortin 2 receptor (MC2R)/accessory protein (MRAP) in the fetal adrenal of the nonhuman primate.

Role of vascular endothelial growth factor and placental growth factor expression on placenta structure in pre-eclamptic pregnancy

AIM

Pre-eclampsia is a hypertensive disease that is characterized by high blood pressure and proteinuria after 20 gestational weeks and complicates 3-8% of all pregnancies. It is classified as either mild or severe pre-eclampsia according to severity, and the aim of this study was to investigate the structural differences between these two classifications.

METHODS

Placenta samples were collected from 68 women who underwent cesarean delivery. Total volume of villi and numerical density of vascular endothelial growth factor (VEGF)- and placental growth factor (PIGF)-positive cells were estimated on stereology and evaluated using one-way ANOVA.

RESULTS

There was no significantly difference in total villi volumes between the groups (P > 0.05). In contrast, on immunohistochemistry, the numerical density of VEGF-positive cells in severe pre-eclampsia was significantly different to the control and mild pre-eclampsia groups (P<0.05). Additionally, the numerical density of PIGF-positive cells in the mild and severe pre-eclampsia group was significantly higher than in the control group (P<0.01).

CONCLUSION

There is no relationship between villi volume and pre-eclampsia, although growth factors play a role in placental changes. The present results were supported by histopathology and several studies in the literature.

Novel expression of EGFL7 in placental trophoblast and endothelial cells and its implication in preeclampsia

The mammalian placenta is the site of nutrient and gas exchange between the mother and fetus, and is comprised of two principal cell types, trophoblasts and endothelial cells. Proper placental development requires invasion and differentiation of trophoblast cells, together with coordinated fetal vasculogenesis and maternal vascular remodeling. Disruption in these processes can result in placental pathologies such as preeclampsia (PE), a disease characterized by late gestational hypertension and proteinuria. Epidermal Growth Factor Like Domain 7 (EGFL7) is a largely endothelial-restricted secreted factor that is critical for embryonic vascular development, and functions by modulating the Notch signaling pathway. However, the role of EGFL7 in placental development remains unknown. In this study, we use mouse models and human placentas to begin to understand the role of EGFL7 during normal and pathological placentation. We show that Egfl7 is expressed by the endothelium of both the maternal and fetal vasculature throughout placental development. Importantly, we uncovered a previously unknown site of EGFL7 expression in the trophoblast cell lineage, including the trophectoderm, trophoblast stem cells, and placental trophoblasts. Our results demonstrate significantly reduced Egfl7 expression in human PE placentas, concurrent with a downregulation of Notch target genes. Moreover, using the BPH/5 mouse model of PE, we show that the downregulation of Egfl7 in compromised placentas occurs prior to the onset of characteristic maternal signs of PE. Together, our results implicate Egfl7 as a possible factor in normal placental development and in the etiology of PE.

Vinclozolin exposure throughout pregnancy and its developmental toxicity

Vinclozolin administration effects: placenta, fetal tissues and skeletal measurements during pregnancy.

Vascular endothelial growth factor and its receptors in the placental villi of pregnant patients with pre-eclampsia

Comparative morphological study of the placentas from women with pre-eclampsia of different severity was carried out. The expression of vascular endothelial growth factor and its receptors (VEGFR-1, VEGFR-2, VEGFR-3) was studied by immunohistochemical methods. Branched angiogenesis processes predominated in the placentas of patients with pre-eclampsia. The syncytiocapillary membranes were thickened, the number of syncytial buds was greater than normally. Immunohistochemical studies showed high expression of VEGF and VEGFR-1 and low expression of VEGFR-2 in the placental villous structures.

VEGF, PIGF and HIF-1α in placentas of early- and late-onset pre-eclamptic patients

PURPOSE

The aim of this study was to compare the VEGF, PIGF, and HIF-1α levels in the placentas of early- and late-onset pre-eclamptic patients, which are thought to be important in pathophysiology of pre-eclampsia.

MATERIAL AND METHOD

Pre-eclamptic early-onset (n = 22) and late-onset (n = 24) pregnant women and a control group of healthy pregnant women (n = 22) were recruited for this case-control study. A semi-quantitative immunohistochemical analysis of VEGF, PIGF and HIF-1α was performed in cross-sections of the placentas of the subjects, after which results were compared.

RESULTS

Levels of VEGF and PIGF in the placentas of pre-eclamptic patients were found to be lower than the levels in the placentas of healthy pregnant women (p < 0.001 and p = 0.025, respectively), whereas the levels of HIF-1α were found significantly higher (p < 0.001). No difference was observed in terms of VEGF, PIGF and HIF-1α in a comparison of the early- and late-onset pre-eclampsia groups (p > 0.05).

CONCLUSION

The results of the study indicated that there is no relationship between the time of onset of pre-eclampsia and the placental changes that occur in these factors.

The differential expression of Kiss1, MMP9 and angiogenic regulators across the feto-maternal interface of healthy human pregnancies: implications for trophoblast invasion and vessel development

Genes involved in invasion of trophoblast cells and angiogenesis are crucial in determining pregnancy outcome. We therefore studied expression profiles of these genes in both fetal and maternal tissues to enhance our understanding of feto-maternal dialogue. We investigated the expression of genes involved in trophoblast invasion, namely Kiss1, Kiss1 Receptor (Kiss1R) and MMP9 as well as the expression of angiogenic ligands Vascular Endothelial Growth Factor-A (VEGF-A) and Prokineticin-1 (PROK1) and their respective receptors (VEGFR1, VEGFR2 and PROK1R) across the feto-maternal interface of healthy human pregnancies. The placenta, placental bed and decidua parietalis were sampled at elective caesarean delivery. Real-time RT-PCR was used to investigate transcription, while immunohistochemistry and western blot analyses were utilized to study protein expression. We found that the expression of Kiss1 (p<0.001), Kiss1R (p<0.05) and MMP9 (p<0.01) were higher in the placenta compared to the placental bed and decidua parietalis. In contrast, the expression of VEGF-A was highest in the placental bed (p<0.001). While VEGFR1 expression was highest in the placenta (p<0.01), the expression of VEGFR2 was highest in the placental bed (p<0.001). Lastly, both PROK1 (p<0.001) and its receptor PROK1R (p<0.001) had highest expression in the placenta. Genes associated with trophoblast invasion were highly expressed in the placenta which could suggest that the influence on invasion capacity may largely be exercised at the fetal level. Furthermore, our findings on angiogenic gene expression profiles suggest that angiogenesis may be regulated by two distinct pathways with the PROK1/PROK1R system specifically mediating angiogenesis in the fetus and VEGFA/VEGFR2 ligand-receptor pair predominantly mediating maternal angiogenesis.

The role of angiogenic, anti-angiogenic and vasoactive factors in pre-eclamptic African women: early- versus late-onset pre-eclampsia

Abstract

The pathogenesis and aetiology of pre-eclampsia (PE) is still unclear. We investigated the role of angiogenic, anti-angiogenic and vasoactive factors in black South African women with early- and late-onset PE. Serum soluble fms-like tyrosine kinase 1 (sFlt-1), soluble vascular endothelial growth factor (VEGF) and placental growth factor (PlGF) levels were determined using the ELISA technique, and placental mRNA expression levels of sFlt-1, VEGF, PlGF and AT1 receptors were determined using real-time PCR.

Serum sFlt-1 levels were significantly elevated and PlGF significantly reduced in early-onset PE compared to the normotensive group. Placental VEGF mRNA expression levels were significantly reduced in the late-onset preeclamptic group compared with the normotensives. The placental mRNA expression of AT1 receptor in the late-onset pre-eclamptic group was relatively raised compared to the normotensives, suggesting hypersensitivity to pressor agents.

We believe that the excess of serum sFlt-1 and reduced VEGF and PlGF levels favour an anti-angiogenic state and endothelial dysfunction leading to PE, and that the aetiology and pathogenesis of early- and late-onset PE differ.

Effects of angiogenic factors, antagonists, and podocyte injury on development of proteinuria in preeclampsia

Proteinuria is universal to all patients with preeclampsia. We examined the urinary podocytes in women with preeclampsia (n = 14), gestational hypertension (n = 14), and normal pregnancy. Maternal serum and urinary concentrations of vascular endothelial growth factor (VEGF), placental growth factor (PlGF), and the antiangiogenic factor soluble fms-like tyrosine kinase 1 (sFlt-1) were detected. These concentrations were used to evaluate the urinary excretion of podocytes and the alteration of angiogenic factors and to assess their relationships to proteinuria in preeclampsia. Our studies suggest that the urinary podocyte number and angiogenic factors are correlated with random urine albumin/creatinine ratio and blood pressure. Receiver-operating characteristic (ROC) curves of serum and urinary PlGF and the PlGF/sFlt-1 ratio as well as the presence of podocyturia confirmed their usefulness in distinguishing preeclamptic and normotensive pregnant women. In addition, combinations of serum or urinary PlGF or podocyturia tests in parallel or in series provided the best clue for identifying patients with preeclampsia. We considered that the dysregulation of angiogenic factors and its subsequent podocyte injury may contribute to the mechanism of proteinuria development in preeclampsia.

The vascular endothelial growth factor family in adverse pregnancy outcomes

BACKGROUND

Pre-eclampsia, small-for-gestational-age infants, preterm birth and recurrent miscarriage complicate a significant number of pregnancies. The vascular endothelial growth factor (VEGF) family of angiogenic growth factors is implicated in the pathophysiology of these complications. We aimed to elucidate the role of these angiogenic factors in placentation and to evaluate the predictive value of their protein concentrations and genetic variations in pregnancy complications.

METHODS

We performed a systematic search of PubMed, and retrieved original articles. The search included a combination of terms such as VEGF-A, placental growth factor (PlGF), kinase insert domain receptor, fms-like-tyrosine-kinase receptor 1, soluble fms-like-tyrosine-kinase receptor 1, pre-eclampsia, small-for-gestational-age infants, preterm birth, recurrent miscarriage, placenta, prediction and polymorphisms.

RESULTS

This review summarizes the current knowledge of the roles of the VEGF family in early placentation and of the abnormalities in maternal plasma and placental expression of angiogenic proteins in adverse pregnancy outcomes compared with normal pregnancy. PlGF and sFLT-1 in combination with other clinical and biochemical markers in late first or second trimester appear to predict early-onset pre-eclampsia with a high sensitivity and specificity. However, VEGF family proteins do not have sufficient power to accurately predict late-onset pre-eclampsia, small-for-gestational age pregnancies or preterm birth. Functional polymorphisms in these angiogenic genes are implicated in pregnancy complications, but their contribution appears to be minor.

CONCLUSIONS

Although the VEGF family has important roles in normal and complicated pregnancy, the current predictive value of the VEGF family as biomarkers appears to be limited to early-onset pre-eclampsia.

Transcriptome landscape of the human placenta

BACKGROUND

The placenta is a key component in understanding the physiological processes involved in pregnancy. Characterizing genes critical for placental function can serve as a basis for identifying mechanisms underlying both normal and pathologic pregnancies. Detailing the placental tissue transcriptome could provide a valuable resource for genomic studies related to placental disease.

RESULTS

We have conducted a deep RNA sequencing (RNA-Seq) study on three tissue components (amnion, chorion, and decidua) of 5 human placentas from normal term pregnancies. We compared the placental RNA-Seq data to that of 16 other human tissues and observed a wide spectrum of transcriptome differences both between placenta and other human tissues and between distinct compartments of the placenta. Exon-level analysis of the RNA-Seq data revealed a large number of exons with differential splicing activities between placenta and other tissues, and 79% (27 out of 34) of the events selected for RT-PCR test were validated. The master splicing regulator ESRP1 is expressed at a proportionately higher level in amnion compared to all other analyzed human tissues, and there is a significant enrichment of ESRP1-regulated exons with tissue-specific splicing activities in amnion. This suggests an important role of alternative splicing in regulating gene function and activity in specific placental compartments. Importantly, genes with differential expression or splicing in the placenta are significantly enriched for genes implicated in placental abnormalities and preterm birth. In addition, we identified 604-1007 novel transcripts and 494-585 novel exons expressed in each of the three placental compartments.

CONCLUSIONS

Our data demonstrate unique aspects of gene expression and splicing in placental tissues that provide a basis for disease investigation related to disruption of these mechanisms. These data are publicly available providing the community with a rich resource for placental physiology and disease-related studies.

Neonatal programming by immunological challenge: effects on ovarian function in the adult rat

Neonatal exposure to an immunological challenge (lipopolysaccharide, LPS) increases the activity of hypothalamo-pituitary-adrenal axis and sensitises the GNRH pulse generator to the inhibitory influence of stress in adult rats. We investigated the effects of neonatal exposure to LPS on various reproductive parameters during puberty and into adulthood in female rats. LPS (50 μg/kg, i.p.) or saline was administered on postnatal days 3 and 5. Vaginal opening was recorded, and oestrous cyclicity was monitored immediately post puberty and again at 8-9 weeks of age. At 10 weeks of age, the ovaries were removed and the number of follicles was counted, together with the thickness of the theca interna of the largest antral follicles. Ovarian sympathetic nerve activity was assessed immunohistochemically by measurement of the levels of ovarian low-affinity receptor of nerve growth factor (p75NGFR). In rats exposed to LPS in early life, there was a significant delay in puberty and disruption of oestrous cyclicity immediately post puberty, which persisted into adulthood. The follicle reserve was decreased, the thickness of the theca interna increased and the expression profile of ovarian p75NGFR increased in the neonatal LPS-treated animals. These data suggest that exposure to LPS during early neonatal life can have long-term dysfunctional effects on the female reproductive system, which might involve, at least in part, increased ovarian sympathetic nerve activity.

Enhanced angiogenic capacity of human umbilical vein endothelial cells from women with preeclampsia

Maternal and placental angiogenic abnormalities are a common feature of preeclampsia. The aim of this study was to determine if endothelial cells from women with preeclampsia exhibit different angiogenic responses compared to healthy cells. Using the endothelial tube formation assay, we have shown that primary human umbilical vein endothelial cells (HUVECs) isolated from women with preeclampsia display greater levels of in vitro angiogenic branching compared to cells from healthy women. A comparable increase in tube formation was observed in healthy cells cultured at 0.5% O(2). Vascular endothelial growth factor (VEGF) receptor inhibition resulted in a decrease in angiogenesis in both healthy hypoxic cells and cells from women with preeclampsia. These findings demonstrate that HUVECs from women with preeclampsia exhibit inherent differences in their angiogenic capacity which are apparent in the absence of placental or maternal factors.

Risk factors and mediators of the vascular dysfunction associated with hypertension in pregnancy

Normal pregnancy is associated with significant hemodynamic changes and vasodilation in the uterine and systemic circulation in order to meet the metabolic demands of the mother and developing fetus. Hypertension in pregnancy (HTN-Preg) and preeclampsia (PE) are major complications and life-threatening conditions to both the mother and fetus. PE is precipitated by various genetic, dietary and environmental factors. Although the initiating events of PE are unclear, inadequate invasion of cytotrophoblasts into the uterine artery is thought to reduce uteroplacental perfusion pressure and lead to placental ischemia/hypoxia. Placental hypoxia induces the release of biologically active factors such as growth factor inhibitors, anti-angiogenic proteins, inflammatory cytokines, reactive oxygen species, hypoxia-inducible factors, and antibodies to vascular angiotensin II receptor. These bioactive factors affect the production/activity of various vascular mediators in the endothelium, smooth muscle and extracellular matrix, leading to severe vasoconstriction and HTN. As an endothelial cell disorder, PE is associated with decreased vasodilator mediators such as nitric oxide, prostacyclin and hyperpolarizing factor and increased vasoconstrictor mediators such as endothelin, angiotensin II and thromboxane A(2). PE also involves enhanced mechanisms of vascular smooth muscle contraction including intracellular free Ca(2+) concentration ([Ca(2+)](i)), and [Ca(2+)](i) sensitization pathways such as protein kinase C, Rho-kinase and mitogen-activated protein kinase. Changes in extracellular matrix composition and matrix metalloproteases activity also promote vascular remodeling and further vasoconstriction in the uterine and systemic circulation. Characterization of the predisposing risk factors, the biologically active factors, and the vascular mediators associated with PE holds the promise for early detection, and should help design specific genetic and pharmacological tools for the management of the vascular dysfunction associated with HTN-Preg.

Circulating and Vascular Bioactive Factors during Hypertension in Pregnancy

Normal pregnancy is associated with significant vascular remodeling in the uterine and systemic circulation in order to meet the metabolic demands of the mother and developing fetus. The pregnancy-associated vascular changes are largely due to alterations in the amount/activity of vascular mediators released from the endothelium, vascular smooth muscle and extracellular matrix. The endothelium releases vasodilator substances such as nitric oxide, prostacyclin and hyperpolarizing factor as well as vasoconstrictor factors such as endothelin, angiotensin II and thromboxane A(2). Vascular smooth muscle contraction is mediated by intracellular free Ca(2+) concentration ([Ca(2+)](i)), and [Ca(2+)](i) sensitization pathways such as protein kinase C, Rho-kinase and mitogen-activated protein kinase. Extracellular matrix and vascular remodeling are regulated by matrix metalloproteases. Hypertension in pregnancy and preeclampsia are major complications and life threatening conditions to both the mother and fetus, precipitated by various genetic, dietary and environmental factors. The initiating mechanism of preeclampsia and hypertension in pregnancy is unclear; however, most studies have implicated inadequate invasion of cytotrophoblasts into the uterine artery, leading to reduction in the uteroplacental perfusion pressure and placental ischemia/hypoxia. This placental hypoxic state is thought to induce the release of several circulating bioactive factors such as growth factor inhibitors, anti-angiogenic proteins, inflammatory cytokines, reactive oxygen species, hypoxia-inducible factors, and vascular receptor antibodies. Increases in the plasma levels and vascular content of these factors during pregnancy could cause an imbalance in the vascular mediators released from the endothelium, smooth muscle and extracellular matrix, and lead to severe vasoconstriction and hypertension. This review will discuss the interactions between the various circulating bioactive factors and the vascular mediators released during hypertension in pregnancy, and provide an insight into the current and future approaches in the management of preeclampsia.