Maternal serum soluble fms-like tyrosine kinase 1 concentrations are not increased in early pregnancy and decrease more slowly postpartum in women who develop preeclampsia.

OBJECTIVE: We measured maternal serum soluble fms-like tyrosine kinase 1 concentrations across pregnancy and immediately postpartum in women who developed preeclampsia and normal pregnant women. STUDY DESIGN: This was a nested case control study of 113 normal pregnant women and 55 women with preeclampsia. RESULTS: Serum soluble fms-like tyrosine kinase 1 concentrations increased similarly in early pregnancy in both groups. Mean serum soluble fms-like tyrosine kinase 1 concentrations were increased in women who developed preeclampsia, compared with normal pregnant women, and this increase was most pronounced in severe preeclampsia. However, many women with preeclampsia had soluble fms-like tyrosine kinase 1 concentrations similar to normal pregnant women. Lastly, soluble fms-like tyrosine kinase 1 decreased rapidly after delivery, but this decrease was significantly slower in women with severe preeclampsia. CONCLUSION: Increased soluble fms-like tyrosine kinase 1 is not an early-pregnancy event among women who later develop preeclampsia. Increased soluble fms-like tyrosine kinase 1 is more likely to be present in women with severe preeclampsia, but it is not present in all women with preeclampsia. Soluble fms-like tyrosine kinase 1 concentrations decrease more slowly after delivery in women with preeclampsia, consistent with a decreased rate of excretion or continued production.

Extra-placental expression of vascular endothelial growth factor receptor-1, (Flt-1) and soluble Flt-1 (sFlt-1), by peripheral blood mononuclear cells (PBMCs) in normotensive and preeclamptic pregnant women.

The soluble VEGF receptor, sFlt-1 (otherwise referred to as sVEGFR-1), has been implicated in the pathogenesis of preeclampsia. The preeclamptic placenta has been previously demonstrated to produce high levels of the soluble VEGF receptor. Here we tested the hypothesis that peripheral blood mononuclear cells (PBMCs) may also represent an additional source for circulating sFlt-1 during normal and preeclamptic pregnancies. We first demonstrate that preeclamptic placentae show five-fold increased Flt-1 and sFlt-1 mRNA levels. We also show that the Flt-1 and sFlt-1 levels are eight-fold higher in preeclamptic placentae if we collect biopsies without rinsing them in saline to remove excess blood. Cultured villous explants from women with preeclampsia failed to show the increased amount of Flt-1 and sFlt-1 mRNA that was observed in the placental biopsies of normal pregnancy and preeclampsia. Under normoxic conditions the Flt-1 and sFlt-1 mRNA levels in the explants were 3.11+/-0.6 fold in normal pregnancy and 3.6+/-0.4 fold in women with preeclampsia (p = NS by ANOVA). However, the same villous explants showed hypoxic induction of Flt-1 mRNA (NP 3.96+/-0.4 fold, p = NS and PE 5.24+/-0.6 fold, p < 0.05 by ANOVA). We analyzed Flt-1 and sFlt-1 protein levels in the peripheral blood mononuclear cells (PBMCs) to analyze the possibility of an extra-placental sFlt-1 source. Our results indicate that PBMCs of pregnant women are capable of expressing variable amounts of Flt-1 proteins. PBMCs from pregnant women exposed to hypoxia show up-regulation of HIF-1alpha and Flt-1 proteins. PBMCs obtained from women with preeclampsia (n = 9) produced significantly higher amounts of sFlt-1 under normal tissue culture conditions (104.6+/-14.3 pg/ml vs. 46.23+/-5.03 pg/ml, p < 0.05 by ANOVA) and much higher concentrations under hypoxia (196.74+/-26.3pg/ml vs. 83.3+/-13.6pg/ml, p < 0.05 by ANOVA) than PBMCs from normal pregnant women (n = 11). Moreover, analysis of PBMCs from a different group of women with a history of preeclampsia showed persistent abnormality of Flt-1 women one year post-partum. The present study indicates that Flt-1 dysregulation in PBMCs of pregnant women resulting in over-expression of sFlt-1 could be an additional (extra-placental) source of sFlt-1 that contributes to the pathogenesis of preeclampsia.

Maternal and fetal amino acid concentrations and fetal outcomes during pre-eclampsia.

The pathophysiology of pre-eclampsia is contested, but one hypothesis indicates that it is a heterogeneous condition in which only a subset of affected women bear small-for-gestational age (SGA) babies. In intrauterine growth-restricted (IUGR) infants, placental transport of amino acids is diminished and the resulting decrease in cord-blood amino acid concentrations is thought to contribute to their stunted growth. In contrast, the metabolic syndrome (dyslipidaemia, hyperinsulinaemia, hyperglycaemia, hypertension and obesity) which is associated with high amino acid concentrations is more prevalent in women with pre-eclampsia. The focus of this study was to compare maternal and fetal serum amino acid concentrations during normal pregnancy and pre-eclampsia and to evaluate the associations between the amino acid concentrations and fetal growth. The results indicate that maternal and cord-blood amino acid concentrations were significantly higher in women with pre-eclampsia compared with normal pregnant women and the concentrations were inversely associated with measures of infant growth. Maternal and cord-blood amino acid concentrations were also significantly higher in pre-eclamptic mothers with SGA infants compared with pre-eclamptic mothers whose babies were not SGA. These data indicate that, in contrast to IUGR, pre-eclampsia is associated with enhanced placental amino acid transport or reduced fetal amino acid utilization. Furthermore, the data are consistent with the hypothesis that pre-eclampsia is a heterogeneous disease associated with the metabolic syndrome.

Impaired oxygen-dependent reduction of HIF-1alpha and -2alpha proteins in pre-eclamptic placentae.

Pre-eclamptic (PE) placentae overexpress hypoxia inducible transcription factors-1alpha and -2alpha proteins (Biol. Repro. 64: 499-506, 2001; Ibid 1019-1020). Possible explanations include (a) impaired oxygen-dependent reduction, and/or (b) enhanced sensitivity to reduced oxygen. After 18 h equilibration under 21 per cent O(2) atmosphere, we subjected villous explants prepared from placentae of normal pregnant (NP) and pre-eclamptic (PE) women (n=8 each) to 4h of hypoxia (2 per cent oxygen), and then studied the disappearance of HIF-1alpha and -2alpha proteins during subsequent oxygenation over 90 min (21 per cent oxygen). The disappearance of these HIF proteins as assessed by Western analysis was significantly impaired in the pre-eclamptic tissues. Even after 18h equilibration under a 21 per cent O(2) atmosphere, and then a further 4h at 21 per cent O(2), HIF-1alpha and -2alpha protein expression remained increased in villous explants from PE women (both P< 0.04 vs NP). To address whether chronic hypoxia per se (which is believed to exist in the pre-eclamptic placenta) might contribute to these findings, we subjected villous explants from normal placentae (n=6) to 18 h preincubation under 2 per cent or 21 per cent oxygen prior to subsequent incubation for 4h at 2 per cent oxygen and then 90 min at 21 per cent oxygen. The time course of disappearance of HIF proteins during oxygenation was similar irrespective of the 2 per cent or 21 per cent preconditioning. To evaluate oxygen sensitivity, we exposed villous explants from NP and PE women (n=6 each) to different oxygen atmospheres for 4h and measured HIF protein induction. Although the data showed a significant inverse relationship between HIF expression and oxygen concentration, there was no significant difference between the slopes of this relationship for the two groups of women. We conclude that villous explants from PE placentae fail to adequately downregulate HIF protein expression upon oxygenation. This abnormality may contribute to their overexpression in vivo.

Prospective evaluation of 618 pregnant women exposed to parvovirus B19: risks and symptoms.

OBJECTIVE: To assess the risk of maternal parvovirus B19 infection from exposure to various sources and the fetal morbidity of those infections. METHODS: We obtained demographic and occupational information about pregnant women exposed to sources of B19 and about the nature and duration of the exposures. We performed serologic testing 10-14 days after exposure using an indirect capture enzyme-linked immunosorbent assay. Women with immunoglobulin (Ig) M were examined with weekly ultrasound until 12 weeks after exposure, and the outcome of the pregnancy was ascertained from interviews with patients and their obstetricians. Logistic regression analysis was used to determine risk factors for maternal immunity and infection by B19. RESULTS: Of 618 pregnant women exposed, 307 (49.7%) were immune to B19, 259 remained susceptible after exposure, and 52 (16.7% of all susceptibles) contracted B19 infection. None of the 52 fetuses of infected women developed nonimmune hydrops, and there were no fetal deaths attributable to B19 in this group. The relative risk of maternal B19 infection was 2.8 if the source was a related child living in the household (95% confidence interval 1.7, 4.6; P < .001). No significant differences were found for maternal B19 infection in eight categories of maternal occupation. Maternal symptoms of polyarthralgia (46%), fever (19%), and nonspecific rash (38%) were significantly more common (P < .001) in IgM-positive patients than in noninfected women (4.1%, 2.8%, and 5.7%, respectively). Only 17 (33%) of the IgM-positive women were entirely asymptomatic. CONCLUSION: The risk of maternal B19 infection in pregnancy could not be predicted by a gravida's occupation, but it was significantly higher when the source of exposure was her own child. The fetal risk of nonimmune hydrops after maternal B19 infection must be very low. As a consequence, exclusion of pregnant women from the workplace during endemic periods with seasonal clusters of cases is not justified. Weekly fetal ultrasound evaluation in these cases carries a low yield.