Computational fluid dynamic simulations of maternal circulation : wall shear stress in the human placenta and its biological implications

Introduction In the human placenta the maternal blood circulates in the intervillous space (IVS). The syncytiotrophoblast (STB) is in direct contact with maternal blood. The wall shear stress (WSS) exerted by the maternal blood flow on the STB has not been evaluated. Our objective was to determine the physiological WSS exerted on the surface of the STB during the third trimester of pregnancy. Material and Methods To gain insight into the shear stress levels that the STB is expected to experience in vivo, we have formulated three different computational models of varying levels of complexity that reflect different physical representations of the IVS. Computations of the flow fields in all models were performed using the CFD module of the finite element code COMSOL Multi-physics 4.4. The mean velocity of maternal blood in the IVS during the third trimester was measured in vivo with dynamic MRI (0.94 +/- 0.14 mm.s(-1)). To investigate if the in silico results are consistent with physiological observations, we studied the cytoadhesion of human parasitized (Plasmodium falciparum) erythrocytes to primary human STB cultures, in flow conditions with different WSS values. Results The WSS applied to the STB is highly heterogeneous in the IVS. The estimated average values are relatively low (0.5 +/- 0.2 to 2.3 +/- 1.1 dyn.cm(-2)). The increase of WSS from 0.15 to 5 dyn.cm(-2) was associated with a significant decrease of infected erythrocyte cytoadhesion. No cytoadhesion of infected erythrocytes was observed above 5 dyn.cm(-2) applied for one hour. Conclusion Our study provides for the first time a WSS estimation in the maternal placental circulation. In spite of high maternal blood flow rates, the average WSS applied at the surface of the chorionic villi is low (<5 dyn.cm(-2)). These results provide the basis for future physiologicallyrelevant in vitro studies of the biological effects of WSS on the STB

French Experience of 2009 A/H1N1v Influenza in Pregnant Women

BACKGROUND: The first reports on the pandemic influenza 2009 A/H1N1v from the USA, Mexico, and Australia indicated that this disease was associated with a high mortality in pregnant women. The aim of this study was to describe and compare the characteristics of severe critically ill and non-severe pregnant women with 2009 A/H1N1v-related illness in France. METHODOLOGY/PRINCIPAL FINDINGS: A national registry was created to screen pregnant women with laboratory-confirmed 2009 A/H1N1v influenza. Three hundred and fifteen patients from 46 French hospitals were included: 40 patients were admitted to intensive care units (severe outcomes), 111 were hospitalized in obstetric or medical wards (moderate outcomes), and 164 were outpatients (mild outcomes). The 2009 A/H1N1v influenza illness occurred during all pregnancy trimesters, but most women (54%), notably the severe patients (70%), were in the third trimester. Among the severe patients, twenty (50%) underwent mechanical ventilation, and eleven (28%) were treated with extracorporeal membrane oxygenation. Three women died from A/H1N1v influenza. We found a strong association between the development of a severe outcome and both co-existing illnesses (adjusted odds ratio [OR], 5.1; 95% confidence interval [CI], 2.2-11.8) and a delay in oseltamivir treatment after the onset of symptoms (>3 or 5 days) (adjusted OR, 4.8; 95% CI, 1.9-12.1 and 61.2, 95% CI; 14.4-261.3, respectively). Among the 140 deliveries after 22 weeks of gestation known to date, 19 neonates (14%) were admitted to a neonatal intensive care unit, mainly for preterm delivery, and two neonates died. None of these neonates developed 2009 A/H1N1v infection. CONCLUSIONS: This series confirms the high incidence of complications in pregnant women infected with pandemic A/H1N1v observed in other countries but depicts a lower overall maternal and neonatal mortality and morbidity than indicated in the USA or Australia. Moreover, our data demonstrate the benefit of early oseltamivir treatment in this specific population

THU0275 SEVERE PREECLAMPSIA RELATED TO ANTIPHOSPHOLIPID SYNDROME: AN EUROPEAN STUDY OF 40 WOMEN

Background:One of the 3 features of obstetrical antiphospholipid syndrome (APS) is severe preeclampsia (PE). Its time of occurrence, the associated risk of thromboses and systemic lupus erythematosus (SLE) have not been reported yet.Objectives:We analyzed severe PE in a series of women with APS.Methods:We retrospectively collected data of female patients from 5 French internal medicine and 1 Italian rheumatology units. Inclusion criteria were: a severe PE/eclampsia(1), that occurred before 34 weeks of gestation (WG) in patients who met the APS classification criteria(2).Results:40 patients were enrolled (Table 1). Because of known APS/positive aPL/previous obstetrical complications, 23(57.5%) patients were treated during the index PE: 4 with low dose aspirin (LDA), 4 with low molecular weight heparin (LMWH), and 15 with a combination of both. 7 patients were also treated with hydroxychloroquine, 8 with corticosteroids and 3 with immunosuppressants. 17(42.5%) patients received no treatment. 24(60%) live births were observed. During a follow-up period of 3 years, 26(65%) patients had at least 1 new pregnancy, with a total of 38 pregnancies which resulted in 33(86.8%) live births. 57.5% pregnancies who resulted in live births occurred without any maternal or fetal complications. All 26 patients who had at least 1 pregnancy after index PE were treated with LDA; LMWH was given at prophylactic and therapeutic dosage in 13(50%) patients, respectively. No patient experienced 3 consecutive miscarriages.Table 1.40 APS patients with severe PEOverall features (n, %)Patients40 (100)Age at PE, (median, IQR)30.5 (27-33)PE term, WG (median, IQR)25.5 (23-29) Live births24 (60) Birth term, WG (median, IQR)25.5 (23.7-30.3) Associated SLE12 (30)Maternal complications (n, %)25 (62.5) HELLP18 (45) E6 (15) CAPS3 (7.5) Placental abruptions3 (7.5)Fetal complications (n, %)31 (77.5) IUGR18 (45) IUFD11 (2.5) Preterm delivery22 (55)Obstetrical history (n, %) Primiparous21 (52.5) Index PE before APS12 (30)Thrombosis (n, %) Thrombosis before PE index14 (35.0) Thrombosis after PE index2 (5.0)Abs at APS diagnosis (n, %) aPL triple positivity21 (52.5) IgG/IgM anti-cardiolipin34 (85.0) IgG/IgM anti-β2GPI25 (62.5) LAC33 (82.5)Legend to Table 1:PE: preeclampsia; APS: antiphospholipid syndrome; IQR: interquartile range; WG: weeks of gestation; SLE: systemic lupus erythematosus; HELLP: Hemolysis, elevated liver enzymes, low platelet; E: eclampsia; CAPS: catastrophic APS; IUGR: intrauterine growth restriction; IUFD: intrauterine fetal death; CHB: congenital atrioventricular block; aPL: antiphospholipid antibodies; LAC: lupus anticoagulant.Conclusion:Among the APS criteria, "3 consecutive miscarriages criterion" was not found. The majority of patients also experienced thrombosis and SLE before the index PE.References:[1]Diagnosis and Management of preeclampsia and eclampsia. International Journal of Gynecology &Obestetrics 2002;77:67-75.[2]Miyakis S, et al. International consensus statement on an update of the classification criteria for definite antiphospholipid syndrome (APS). J Thromb Haemost 2006;4:295e 306.Disclosure of Interests:Maddalena Larosa: None declared, Nathalie Morel: None declared, Meriem BELHOCINE: None declared, Amelia Ruffatti: None declared, Nicolas Martin Silva: None declared, Romain Paul: None declared, Luc Mouthon: None declared, Michel DREYFUS: None declared, Jean-Charles PIETTE: None declared, Odile Souchaud-Debouverie: None declared, Catherine Deneux-Tharaux: None declared, Vassilis Tsatsaris: None declared, Emmanuelle Pannier: None declared, Gaêlle Guettrot Imbert: None declared, Véronique LE GUERN Grant/research support from: UCB for GR2 study (to our institution), Andrea Doria Consultant of: GSK, Pfizer, Abbvie, Novartis, Ely Lilly, Speakers bureau: UCB pharma, GSK, Pfizer, Janssen, Abbvie, Novartis, Ely Lilly, BMS, Nathalie Costedoat-Chalumeau Grant/research support from: UCB to my institutio

Differential Expression of Vegfr-2 and Its Soluble Form in Preeclampsia

Several studies have suggested that the main features of preeclampsia (PE) are consequences of endothelial dysfunction related to excess circulating anti-angiogenic factors, most notably, soluble sVEGFR-1 (also known as sFlt-1) and soluble endoglin (sEng), as well as to decreased PlGF. Recently, soluble VEGF type 2 receptor (sVEGFR-2) has emerged as a crucial regulator of lymphangiogenesis. To date, however, there is a paucity of information on the changes of VEGFR-2 that occur during the clinical onset of PE. Therefore, the aim of our study was to characterize the plasma levels of VEGFR-2 in PE patients and to perform VEGFR-2 immunolocalization in placenta.By ELISA, we observed that the VEGFR-2 plasma levels were reduced during PE compared with normal gestational age matched pregnancies, whereas the VEGFR-1 and Eng plasma levels were increased. The dramatic drop in the VEGFR-1 levels shortly after delivery confirmed its placental origin. In contrast, the plasma levels of Eng and VEGFR-2 decreased only moderately during the early postpartum period. An RT-PCR analysis showed that the relative levels of VEGFR-1, sVEGFR-1 and Eng mRNA were increased in the placentas of women with severe PE. The relative levels of VEGFR-2 mRNA as well as expressing cells, were similar in both groups. We also made the novel finding that a recently described alternatively spliced VEGFR-2 mRNA variant was present at lower relative levels in the preeclamptic placentas.Our results indicate that the plasma levels of anti-angiogenic factors, particularly VEGFR-1 and VEGFR-2, behave in different ways after delivery. The rapid decrease in plasma VEGFR-1 levels appears to be a consequence of the delivery of the placenta. The persistent circulating levels of VEGFR-2 suggest a maternal endothelial origin of this peptide. The decreased VEGFR-2 plasma levels in preeclamptic women may serve as a marker of endothelial dysfunction

Comparative Methylation of ERVWE1/Syncytin-1 and Other Human Endogenous Retrovirus LTRs in Placenta Tissues

Human endogenous retroviruses (HERVs) are globally silent in somatic cells. However, some HERVs display high transcription in physiological conditions. In particular, ERVWE1, ERVFRDE1 and ERV3, three proviruses of distinct families, are highly transcribed in placenta and produce envelope proteins associated with placenta development. As silencing of repeated elements is thought to occur mainly by DNA methylation, we compared the methylation of ERVWE1 and related HERVs to appreciate whether HERV methylation relies upon the family, the integration site, the tissue, the long terminal repeat (LTR) function or the associated gene function. CpG methylation of HERV-W LTRs in placenta-associated tissues was heterogeneous but a joint epigenetic control was found for ERVWE1 5′LTR and its juxtaposed enhancer, a mammalian apparent LTR retrotransposon. Additionally, ERVWE1, ERVFRDE1 and ERV3 5′LTRs were all essentially hypomethylated in cytotrophoblasts during pregnancy, but showed distinct and stage-dependent methylation profiles. In non-cytotrophoblastic cells, they also exhibited different methylation profiles, compatible with their respective transcriptional activities. Comparative analyses of transcriptional activity and LTR methylation in cell lines further sustained a role for methylation in the control of functional LTRs. These results suggest that HERV methylation might not be family related but copy-specific, and related to the LTR function and the tissue. In particular, ERVWE1 and ERV3 could be developmentally epigenetically regulated HERVs

Stimulation of human trophoblast invasion by placental growth hormone

A critical step in establishment of human pregnancy is the invasion of the uterus wall by the extravillous cytotrophoblast (EVCT), a process regulated by multiple autocrine and paracrine factors. Hormones belonging to the GH/prolactin family are expressed at the maternofetal interface. Because they are involved in cell motility in various models, we examined the possible regulatory role of human placental GH (hPGH) in EVCT invasiveness. By using an in vitro invasion model, we found that EVCT isolated from first-trimester chorionic villi and cultured on Matrigel secreted hPGH and expressed human GH receptor ( hGHR). These data were confirmed by in situ immunohistochemistry. EVCT expressed the full-length and truncated forms of hGHR, and the Janus kinase-2/signal transducer and activator of transcription factor-5 signaling pathway was activated in EVCT by hPGH treatment. Strong hPGH and hGHR expression was observed when EVCT invaded Matrigel and moved through the pores of the filter on which they were cultured. hPGH stimulated EVCT invasiveness, and this effect was inhibited by a Janus kinase-2 inhibitor. Interestingly, hPGH was more efficient than pituitary GH in stimulating EVCT invasiveness. These results offer the first evidence for a placental role of hPGH and suggest an autocrine/ paracrine role of hPGH in the regulation of trophoblast invasion