Soluble fms-like tyrosine kinase 1 (sFlt-1): A novel biochemical marker for acute fatty liver of pregnancy.

INTRODUCTION: Acute fatty liver of pregnancy (AFLP) substantially contributes to maternal and neonatal morbidity and mortality. Other liver-associated pregnancy complications such as preeclampsia-associated HELLP (hemolysis, elevated liver enzyme, low platelet) syndrome may be difficult to differentiate from AFLP as these diseases overlap with regard to multiple clinical and laboratory features. The aim of this study was to investigate angiogenic profiles by measuring soluble fms-like tyrosine kinase-1 (sFlt-1) and placental growth factor (PlGF) in pregnancies compromised by AFLP and to compare them with those complicated by HELLP syndrome. MATERIAL AND METHODS: Pregnant women affected by AFLP or HELLP syndrome were enrolled. The study population of women with HELLP syndrome was part of a larger data collection obtained in our clinic that has been used for previous work. Patients' angiogenic profiles were assessed by measuring sFlt-1 and PlGF serum levels. To assess the diagnostic potential of these angiogenic markers in AFLP, as well as discriminating it from HELLP syndrome, non-parametric tests were used and receiver operating curves were calculated. RESULTS: Six women with AFLP and 48 women with HELLP syndrome were included in the study. Patients with AFLP showed significantly higher sFlt-1 levels (median: 57 570 pg/mL; range 31 609-147 170 pg/mL) than patients with HELLP syndrome (9713 pg/mL; 1348-30 781 pg/mL; p < 0.001). PlGF serum levels were higher in patients with AFLP compared with those with HELLP syndrome (197 pg/mL; 127-487 pg/mL vs. 40 pg/mL; 9-644 pg/mL, respectively; p < 0.01). sFlt-1/PlGF ratios were not significantly different between AFLP and HELLP syndrome patients (192; 157-1159 vs. 232; 3-948, respectively; NS). In our study population, an sFlt-1 cut-off value of 31 100 pg/mL allowed differentiation between these two diseases with a sensitivity and specificity of 100%. A linear correlation was found between the cumulative numbers of Swansea criteria and sFlt-1 serum levels (r = 0.97; p < 0.01). CONCLUSIONS: AFLP is associated with very high sFlt-1 serum levels in particular in women fulfilling eight or more Swansea criteria. Besides the suggested Swansea criteria to diagnose AFLP, an sFlt-1 value above 31 100 pg/mL may be an additional biochemical feature improving discrimination between AFLP and HELLP syndrome. However, because of the small number of pregnancies affected by AFLP included in this work further studies are needed to corroborate our findings.

Ultra-high sensitive C-reactive protein during normal pregnancy and in preeclampsia: a pilot study.

INTRODUCTION: Angiogenic and inflammatory factors have been shown to play an important role in the pathogenesis of preeclampsia. However, there is little information on their interaction. The aims of this study were to investigate the longitudinal pattern of inflammatory markers, such as interleukin-6 (IL-6) and C-reactive protein (CRP) using a novel ultra-high sensitive assay method (uhsCRP), and to explore their relationship with angiogenic factors such as placental growth factor (PLGF), soluble fms-like tyrosine kinase-1 (sFlt-1), and vascular endothelial growth factor (VEGF) in normal pregnancies and pregnancies complicated by preeclampsia. MATERIALS AND METHODS: Serum levels of uhsCRP, IL-6, PLGF, VEGF and s-Flt-1 were longitudinally determined in 16 women with normal, singleton healthy pregnancies at 7-13, 17-22, 27-31 and 37-41 weeks of gestation by ELISA. uhsCRP was measured using a ultra-high sensitivity ELISA test. Serum of women with preeclampsia (n = 15) was available only once, usually in the third trimester of pregnancy. Women with premature rupture of membranes (PROM) or infection such as chorioamnionitis were excluded. Spearman rank correlation, logistic regression, ROC analysis, ANOVA and Mann-Whitney U-test were used for statistical purposes. RESULTS: In normal pregnancies, serum uhsCRP showed a gestational age-dependent increase (r = 0.40; P < 0.001). In women suffering from preeclampsia, uhsCRP levels were higher than in gestational age-matched controls (18010 ±â€Š4763 versus 3026 ±â€Š587 ng/ml; P < 0.001). Similarly, serum IL-6 levels increased throughout pregnancy and correlated with uhsCRP in normal pregnancies and in preeclampsia (n = 64, r = 0.37; P < 0.01 and n = 15, r = 1.00, P < 0.0001). uhsCRP levels were positively correlated with sFlt-1 levels (n = 64, r = 0.34; P < 0.01). CONCLUSION: The increases in uhsCRP (and IL-6) serum levels with advancing gestation indicate a shift towards an inflammatory state during normal pregnancy. The excessive rise in uhsCRP and sFlt-1 in preeclampsia indicate that both may be involved in its pathogenesis. uhsCRP may be useful as an early marker for preeclampsia and studies defining the pattern of its rise throughout pregnancies at risk are urgently needed.

Expression, purification, and structural insights for the human uric acid transporter, GLUT9, using the Xenopus laevis oocytes system.

The urate transporter, GLUT9, is responsible for the basolateral transport of urate in the proximal tubule of human kidneys and in the placenta, playing a central role in uric acid homeostasis. GLUT9 shares the least homology with other members of the glucose transporter family, especially with the glucose transporting members GLUT1-4 and is the only member of the GLUT family to transport urate. The recently published high-resolution structure of XylE, a bacterial D-xylose transporting homologue, yields new insights into the structural foundation of this GLUT family of proteins. While this represents a huge milestone, it is unclear if human GLUT9 can benefit from this advancement through subsequent structural based targeting and mutagenesis. Little progress has been made toward understanding the mechanism of GLUT9 since its discovery in 2000. Before work can begin on resolving the mechanisms of urate transport we must determine methods to express, purify and analyze hGLUT9 using a model system adept in expressing human membrane proteins. Here, we describe the surface expression, purification and isolation of monomeric protein, and functional analysis of recombinant hGLUT9 using the Xenopus laevis oocyte system. In addition, we generated a new homology-based high-resolution model of hGLUT9 from the XylE crystal structure and utilized our purified protein to generate a low-resolution single particle reconstruction. Interestingly, we demonstrate that the functional protein extracted from the Xenopus system fits well with the homology-based model allowing us to generate the predicted urate-binding pocket and pave a path for subsequent mutagenesis and structure-function studies.

Regulation of human trophoblast GLUT1 glucose transporter by insulin-like growth factor I (IGF-I).

Glucose transport to the fetus across the placenta takes place via glucose transporters in the opposing faces of the barrier layer, the microvillous and basal membranes of the syncytiotrophoblast. While basal membrane content of the GLUT1 glucose transporter appears to be the rate-limiting step in transplacental transport, the factors regulating transporter expression and activity are largely unknown. In view of the many studies showing an association between IGF-I and fetal growth, we investigated the effects of IGF-I on placental glucose transport and GLUT1 transporter expression. Treatment of BeWo choriocarcinoma cells with IGF-I increased cellular GLUT1 protein. There was increased basolateral (but not microvillous) uptake of glucose and increased transepithelial transport of glucose across the BeWo monolayer. Primary syncytial cells treated with IGF-I also demonstrated an increase in GLUT1 protein. Term placental explants treated with IGF-I showed an increase in syncytial basal membrane GLUT1 but microvillous membrane GLUT1 was not affected. The placental dual perfusion model was used to assess the effects of fetally perfused IGF-I on transplacental glucose transport and syncytial GLUT1 content. In control perfusions there was a decrease in transplacental glucose transport over the course of the perfusion, whereas in tissues perfused with IGF-I through the fetal circulation there was no change. Syncytial basal membranes from IGF-I perfused tissues showed an increase in GLUT1 content. These results demonstrate that IGF-I, whether acting via microvillous or basal membrane receptors, increases the basal membrane content of GLUT1 and up-regulates basal membrane transport of glucose, leading to increased transepithelial glucose transport. These observations provide a partial explanation for the mechanism by which IGF-I controls nutrient supply in the regulation of fetal growth.

A randomized comparison of microtip and air-charged catheter for the measurement of maximum urethral closure pressure.

BACKGROUND: Measurements of maximum urethral closure pressure (MUCP) are a part of urodynamic investigations preceding an incontinence surgery and a part of urethral function tests. OBJECTIVES: The aim of the study was to compare maximum urethral closure pressure determined by a microtip catheter with those measured by an air-charged catheter. MATERIAL AND METHODS: A prospective randomized study in a tertiary referral centre. 122 female patients with urodynamic stress incontinence were randomly assigned to have their urethral pressure profiles measured at rest by both microtip and air-charged catheters. INTERVENTION AND MEASUREMENTS: Each patient had three measurements taken by each catheter type. Means of the measurements were compared with regard to correlation and repeatability. For statistical analysis, an approach proposed by Bland-Altman was applied to assess the agreement between the two techniques. RESULTS: Correlation coefficient between MUCP by the air-charged and the microtip catheter was r=0.8507 (95% CI 0.7928 - 0.8934; p<0.0001). MUCP by the air-charged catheter was significantly lower than MUCP measured by the microtip catheter. The two-tailed p value was <0.0001, considered extremely significant. (95% CI of the differences; mean difference = -3.033; mean of paired differences -3.730 to -2.335). Discrepancies between measurements of the microtip and the air-charged catheters suggest good agreement between the two catheters since the mean difference was 2.8 cmH2O and the 95% CI of agreement were narrow with -0.03319 to 0.3151. CONCLUSION: Air-charged catheters give lower readings for MUCP than microtip catheters with a good agreement between the two catheters.

Neurogenic characteristics of placental stem cells in preeclampsia.

OBJECTIVE: Preeclampsia is associated with perinatal brain injury. Autologous placenta stem cell transplantation represents a promising future treatment option for neuroregeneration. The aim of this study was to compare the neuroregenerative capacity of preeclampsia-placenta stem cells to previously characterized placentas from uncomplicated pregnancies. STUDY DESIGN: Placenta stem cells from amnion (epithelium, mesenchyme) and chorion were assessed for cell surface markers and the formation of neuronal-like cells, oligodendrocytes and their progenitors in culture. RESULTS: Markers of preeclampsia-placenta stem cells were different from uncomplicated pregnancies-placenta stem cells in amnion epithelium and chorion, but not in amnion mesenchyme. Similarly to uncomplicated pregnancies-placenta stem cells, preeclampsia-placenta stem cells derived from amnion and chorion differentiated preferably into nestin-positive stem/progenitor cells and Tuj-1-positive neurons. However, other important markers were varying after neurogenic differentiation of uncomplicated pregnancies- and preeclampsia-placenta stem cells. CONCLUSION: Surface marker expression patterns of preeclampsia-placenta stem cell's and uncomplicated pregnancies-placenta stem cell's differ. In vitro differentiation assays, however, provide evidence that both preeclampsia-placenta stem cells and uncomplicated pregnancies-placenta stem cells are comparably suitable for neuroregeneration purposes.

First-trimester serum levels of soluble endoglin and soluble fms-like tyrosine kinase-1 as first-trimester markers for late-onset preeclampsia.

OBJECTIVE: The aim of this investigation was to assess soluble endoglin (sEng) and soluble fms-like tyrosine kinase-1 (sFlt1) as first-trimester serum markers to predict preeclampsia. STUDY DESIGN: First-trimester sera were obtained from 46 women with subsequent late-onset preeclampsia and from 92 controls. sEng and sFlt1 concentrations were determined immunoanalytically. Correlation analysis with inhibin A and placental growth factor levels was performed. RESULTS: sEng and sFlt1 serum concentrations were higher in women with subsequent preeclampsia than in controls (mean +/- SD, sEng: 5.57 +/- 1.18 ng/mL vs 5.02 +/- 1.01 ng/mL, P = .009; sFlt1: 1764 +/- 757 pg/mL vs 1537 +/- 812 pg/mL, P = .036). Sensitivities and specificities for predicting preeclampsia were 63% and 57% for sEng and 64% and 56% for sFlt1, respectively. When sEng and inhibin A were combined, the sensitivity increased to 68%, whereas the specificity was 61%. CONCLUSION: sEng and sFlt1 are increased in the first trimester in women with subsequent late-onset preeclampsia and might therefore prove useful to predict preeclampsia.

Hypoxic upregulation of glucose transporters in BeWo choriocarcinoma cells is mediated by hypoxia-inducible factor-1.

Placental hypoxia has been implicated in pregnancy pathologies, including fetal growth restriction and preeclampsia; however, the mechanism by which the trophoblast cell responds to hypoxia has not been adequately explored. Glucose transport, a process crucial to fetoplacental growth, is upregulated by hypoxia in a number of cell types. We investigated the effects of hypoxia on the regulation of trophoblast glucose transporter (GLUT) expression and activity in BeWo choriocarcinoma cells, a trophoblast cell model, and human placental villous tissue explants. GLUT1 expression in BeWo cells was upregulated by the hypoxia-inducing chemical agents desferroxamine and cobalt chloride. Reductions in oxygen tension resulted in dose-dependent increases in GLUT1 and GLUT3 expression. Exposure of cells to hypoxic conditions also resulted in an increase in transepithelial glucose transport. A role for hypoxia-inducible factor (HIF)-1 was suggested by the increase in HIF-1alpha as a result of hypoxia and by the increase in GLUT1 expression following treatment of BeWo with MG-132, a proteasomal inhibitor that increases HIF-1 levels. The function of HIF-1 was confirmed in experiments where the hypoxic upregulation of GLUT1 and GLUT3 was inhibited by antisense HIF-1alpha. In contrast to BeWo cells, hypoxia produced minimal increases in GLUT1 expression in explants; however, treatment with MG-132 did upregulate syncytial basal membrane GLUT1. Our results show that GLUTs are upregulated by hypoxia via a HIF-1-mediated pathway in trophoblast cells and suggest that the GLUT response to hypoxia in vivo will be determined not only by low oxygen tension but also by other factors that modulate HIF-1 levels.