Hirotada Suzuki

Alterations in Placental Growth Factor Levels before and after the Onset of Preeclampsia Are More Pronounced in Women with Early Onset Severe Preeclampsia

It has been established that the serum placental growth factor (PlGF) decreases and the soluble fms-like tyrosine kinase-1 (sFlt-1) increases in women with preeclampsia. However, there have been no studies on the relation between preeclampsia onset time and the changes in PlGF and sFlt-1. Furthermore, the PlGF and sFlt-1 levels have not been evaluated using their reference values specific to each gestational age. In this study we reevaluated the serum PlGF and sFlt-1 levels before and after the clinical manifestation of early and late onset severe preeclampsia using the new reference values developed in our recent longitudinal study. Blood specimens were obtained immediately after the clinical manifestation of severe preeclampsia in 34 referred women, and both before and after the clinical manifestation in 8 women receiving a routine checkup at our institute. Both women with early and those with late preeclampsia showed decreased PlGF and increased sFlt-1 levels compared to normotensive controls at 28 and 37 weeks (n=68). However, those with early onset preeclampsia had a higher incidence of low PlGF (<5th percentile on the reference values) and high sFlt-1 (≥95th percentile) than those with late onset (low PlGF: 93% vs. 55%; high sFlt-1: 100% vs. 60%). log10PlGF (r=0.574, p<0.001) and log10(sFlt-1/PlGF) (r=−0.556, p<0.001) were correlated with the week of onset of preeclampsia. Before the onset of preeclampsia, the incidence rate of low PlGF in the women with early onset preeclampsia was 100% (5/5), whereas that in the women with late onset preeclampsia was 0% (0/2) (p=0.048). Therefore, alterations in the PlGF levels both before and after the onset of preeclampsia may be more pronounced in women with early onset than those with late onset severe preeclampsia.

Evaluation of a new and automated electrochemiluminescence immunoassay for plasma sFlt-1 and PlGF levels in women with preeclampsia.

The first commercial automated immunoassays specific for soluble fms-like tyrosine kinase 1 (sFlt-1) and placental growth factor (PlGF) (Elecsys sFlt-1 and Elecsys PlGF, respectively) have recently been introduced. We constructed reference range values of plasma levels of sFlt-1 and PlGF, and the sFlt-1/PlGF ratio using Elecsys sFlt-1 and Elecsys PlGF during the second half of pregnancy and evaluated their sensitivity and specificity for the diagnosis of preeclampsia. Plasma samples were collected from 144 normal pregnant women at 19–25, 27–31 and 34–38 weeks of gestation and from 34 women with preeclampsia. The most appropriate reference range curves for plasma levels of sFlt-1 and PlGF, and the sFlt-1/PlGF ratio are presented as quadratic curves after logarithmic transformation. The sFlt-1/PlGF ratio showed the best diagnostic power for both early-onset and late-onset preeclampsia. In addition, a cutoff value of 45 for the sFlt-1/PlGF ratio resulted in the best sensitivity and specificity for the diagnosis of all preeclampsia (97 and 95%, respectively), and for the diagnosis of early-onset preeclampsia (100 and 95%, respectively). Using another 50 pairs of serum and plasma samples, including those from normal pregnant women and preeclamptic women, the plasma recovery rates of sFlt-1 and PlGF were 0.89 and 0.85, respectively; the correlation determinations between serum and plasma samples were 0.999 for sFlt-1, 0.990 for PlGF and 0.987 for sFlt-1/PlGF ratio. In conclusion, measurement of the plasma sFlt-1/PlGF ratio determined by Elecsys sFlt-1 and Elecsys PlGF and using a cutoff value of 45 might assist in the diagnosis of preeclampsia, especially for early-onset preeclampsia.

Effect of Recombinant Placental Growth Factor 2 on Hypertension Induced by Full-Length Mouse Soluble fms-Like Tyrosine Kinase 1 Adenoviral Vector in Pregnant Mice

The first aim of our study was to develop a pregnant mouse model for preeclampsia using adenoviral vector containing mouse full-length soluble fms-like tyrosine kinase 1 (sFlt-1) but not truncated sFlt-1. The second aim was to evaluate effects of recombinant mouse (rm) vascular endothelial growth factor (VEGF) and rm placental growth factor (PlGF) on a preeclampsia model induced by adenoviral vector containing mouse full-length sFlt-1. We injected adenoviral vector containing mouse full-length sFlt-1 on day 8.5 or 9.5 of gestation into pregnant Institute of Cancer Research mice, resulting in hypertension, proteinuria, and similar glomerular histological changes as those seen in human preeclamptic women with glomerular endotheliosis on day 16.5 or 17.5 of gestation. The preeclampsia models were treated with 100 &mgr;g/kg of rmVEGF164 (n=5), 100 &mgr;g/kg of rmPlGF-2 (n=5), or vehicle (n=7) twice a day for 2 days IP. The rmVEGF164 treatment significantly decreased the mean blood pressure on day 16.5 or 17.5 of gestation compared with the vehicle treatment (85±4 versus 97±2 mm Hg; P=0.018). The rmPlGF-2 treatment also significantly decreased the mean blood pressure on day 16.5 or 17.5 of gestation compared with the vehicle treatment (86±3 versus 97±2 mm Hg; P=0.018). However, proteinuria was not affected by either rmVEGF164 or rmPlGF-2. In conclusion, we, for the first time, created a mouse preeclampsia model using mouse full-length sFlt-1. VEGF and PlGF may be promising for ameliorating hypertension in women with preeclampsia. Additional study of PlGF as a potential drug for preeclampsia is warranted.

Normal and High-Normal Blood Pressures, but Not Body Mass Index, Are Risk Factors for the Subsequent Occurrence of Both Preeclampsia and Gestational Hypertension: A Retrospective Cohort Study

Blood pressure (BP) levels and body mass index (BMI) are known as risk factors for preeclampsia and gestational hypertension. However, there have been few investigations regarding the effects of BP and BMI levels on preeclampsia and gestational hypertension in the same cohort. In the present study, we conducted a retrospective cohort study using multiple logistic regression analysis. The cohort included 1,518 patients without nephritis. The unadjusted odds ratios (ORs) of preeclampsia and gestational hypertension were increased in pregnant women with normal BP (120–129 mmHg systolic or 80–84 mmHg diastolic), high-normal BP and hypertension in the second trimester compared to those with optimal BP. The unadjusted ORs of preeclampsia and gestational hypertension were also increased in obese women in the pre-pregnancy period compared to women with normal range BMI. When adjustment was made for both the BP levels and pre-pregnancy BMI levels, the ORs (95% confidence intervals) of normal BP, high-normal BP, hypertension and obesity for the subsequent occurrence of preeclampsia were 5.1 (2.2–12), 8.3 (3.1–22), 16 (5.0–50) and 2.0 (0.67–5.9), and those for the subsequent occurrence of gestational hypertension were 7.0 (2.6–19), 7.4 (2.1–25), 22 (6.1–83) and 1.3 (0.33–4.8), respectively. For the subsequent occurrence of preeclampsia or gestational hypertension, normal BP, high-normal BP and hypertension in the second trimester may be independent risk factors. Obesity in the pre-pregnancy period, however, may not be an independent risk factor.

Establishing Reference Values for Both Total Soluble Fms-Like Tyrosine Kinase 1 and Free Placental Growth Factor in Pregnant Women

It has been reported that the concentration of free placental growth factor (PlGF) is decreased and that of soluble fms-like tyrosine kinase 1 (sFlt-1) is increased before the onset of preeclampsia. However, no study has determined the reference values for sFlt-1 and free PlGF during pregnancy using a commercially available enzyme-linked immunosorbent assay (ELISA) kit. This longitudinal cohort study was undertaken to address this issue. Serum samples were collected from 148 women at 10, 18, 28, and 37 weeks of gestation. Preeclampsia occurred in 6 women: 4 women who delivered at <37 weeks of gestation, and 2 women who delivered at ≥37 weeks. The average and 90% confidence interval (90% CI) of the serum concentration of both sFlt-1 and free PlGF were determined in a total of 433 specimens from 148 subjects with 1 to 4 collections at 7 to 39 weeks of gestation, and were represented as quadric curves. The mean values (90% CI) of sFlt-1 (pg/ml) at 10, 18, 28, and 37 weeks of gestation were 413 (174–981), 296 (125–704), 413 (174–982), and 1,130 (477–2,690), respectively. The mean values (90% CI) of free PlGF (pg/ml) were 36 (14–89), 206 (83–515), 518 (207–1,290), and 354 (142–884), respectively. We also established the reference values for the ratio of sFlt-1/PlGF. These values may be useful for predicting the subsequent occurrence of preeclampsia.

Alteration of serum soluble endoglin levels after the onset of preeclampsia is more pronounced in women with early-onset.

It has been established that serum soluble endoglin (sEng) increases in women with preeclampsia. However, sEng levels have not been evaluated using a normal reference value specific to each gestational age. First, we established the normal reference value for sEng using 85 pregnant controls without preeclampsia, from whom serum samples were collected three times at 20–23, 27–30, and 36–38 weeks of gestation. Second, we evaluated the serum sEng levels after the onset of preeclampsia in 56 preeclamptic patients. In three women (3.5%) with normal pregnancies, sustained high sEng levels (>15 ng/mL) were observed. We calculated the reference value for sEng using the remaining 82 normal controls. The log10sEng was almost normally distributed at each gestational week during 20–38 weeks, and the mean log10sEng was represented as a quadratic curve of gestational week. The SD of log10sEng was represented as a linear equation of gestational week. The mean log10sEng significantly and gradually increased from 20–23 weeks to 27–30 weeks of gestation and then rapidly increased at 36–38 weeks of gestation. Ninety-three percent of preeclamptic women showed sEng≥95th percentile of the reference value. The log10sEng levels and the SD score (SDS) of log10sEng in women with early-onset preeclampsia (onset<32 weeks of gestation) were significantly higher than those in women with late-onset preeclampsia (onset≥32 weeks of gestation) (1.97±0.23 vs. 1.78±0.28, 9.94±2.61 vs. 4.47±2.06, respectively). In conclusion, alteration of serum sEng levels after the onset of preeclampsia was more pronounced in women with early-onset preeclampsia compared to those with late onset.

Onset threshold of the plasma levels of soluble fms-like tyrosine kinase 1/placental growth factor ratio for predicting the imminent onset of preeclampsia within 4 weeks after blood sampling at 19–31 weeks of gestation

Our aim was to evaluate the onset threshold of plasma levels of the soluble fms-like tyrosine kinase 1 (sFlt-1)/placental growth factor (PlGF) ratio for predicting the imminent onset of preeclampsia (PE) within 4 weeks after blood sampling. We prospectively measured the plasma levels of sFlt-1 and PlGF by an automated electrochemiluminescence immunoassay at 19–25 weeks of gestation in 1199 women and at 26–31 weeks of gestation in 798 women. The onset threshold of the sFlt-1/PlGF ratio was determined as the 2.5th percentile of the 95th confidence interval (CI) of a regression line between the onset gestational weeks of PE and the standard deviation score of log10(sFlt-1/PlGF), using 25 samples taken within 1 week after the onset of PE. The imminent onset of PE was identified in 2 (0.2%) women recruited at 19–25 weeks and in 6 (0.8%) women recruited at 26–31 weeks. The onset threshold of plasma levels of the sFlt-1/PlGF ratio at 19–25 weeks showed a sensitivity (SE) of 1.00, a specificity (SP) of 1.00, a positive likelihood ratio (LR+) of ∞ and a positive predictive value (PPV) of 1.00; the onset threshold of plasma levels of the sFlt-1/PlGF ratio at 26–31 weeks showed a SE of 0.83, a SP of 0.994, a LR+ of 132 (95% CI: 51–339) and a PPV of 0.50. In conclusion, the onset threshold of plasma levels of the sFlt-1/PlGF ratio was shown to be a highly sensitive and a highly specific screening method for detecting the imminent onset of PE within 4 weeks after blood sampling at 19–31 weeks.

Serum sFlt1:PlGF Ratio, PlGF, and Soluble Endoglin Levels in Gestational Proteinuria

Objective: It was recently reported that both a high soluble fms-like tyrosine kinase 1 (sFlt1): placental growth factor (PlGF) ratio (sFlt1:PlGF ratio) and high soluble endoglin (sEng) levels are related to the later occurrence of preeclampsia. We compared the serum sFlt1:PlGF ratio, PlGF and sEng levels in women with gestational proteinuria (GP) to those in women with preeclampsia. Methods: Seven women with GP and 34 women with preeclampsia were recruited in this study. The 95th percentile values in the reference curves of sFlt1, sFlt1:PlGF ratio and sEng, and the 5th percentile values in the reference curve of PlGF were respectively set as the cutoff values. Results: The incidence rates of a high sFlt1:PlGF ratio, low PlGF and high sEng in women with GP were 57%, 29% and 86%, respectively, whereas those in women with preeclampsia were 94%, 77%, and 88%, respectively (p = 0.028, p = 0.024, and p = 1.000, respectively). The incidence rates of a both high sFlt1:PlGF ratio and high sEng in women with GP and preeclampsia were 57% and 88%, respectively (p = 0.082). Conclusion: The majority of women with GP showed both increases of the sFlt1:PlGF ratio and sEng, thus suggesting some women with GP may represent subclinical preeclampsia. In addition, women with GP showed a significantly lower sFlt1:PlGF ratio and higher PlGF level than those with preeclampsia, suggesting that the PlGF level is a key regulator for developing hypertension in some pregnant women, even with increases of both sFlt1:PlGF ratio and sEng levels.

Anterior placentation as a risk factor for massive hemorrhage during cesarean section in patients with placenta previa.

In placenta previa (PP), anterior placentation, compared with posterior placentation, is reported to more frequently cause massive hemorrhage during cesarean section (CS). Whether this is due to the high incidence of placenta accreta, previous CS, or a transplacental approach in anterior placenta is unclear. We attempted to clarify this issue.

Gestational hypertension as a subclinical preeclampsia in view of serum levels of angiogenesis-related factors.

It is controversial whether gestational hypertension (GH) and preeclampsia (PE) have the same pathophysiology. Our aim was to clarify whether the serum soluble fms-like tyrosine kinase 1 (sFlt-1)/placental growth factor (PlGF) ratio and levels of soluble endoglin (sEng) are different in women with GH and with PE. In women with GH (15 cases), hypertension preceding PE (h-PE, 10 cases) and PE in which hypertension and proteinuria occurred simultaneously (si-PE, 36 cases), blood samples were collected after disease onset. The levels of log10(sFlt-1/PlGF) in women with GH were significantly lower than in women with h-PE and si-PE (1.65±0.39 vs. 2.22±0.35 and 2.15±0.46). The levels of log10sEng in women with GH were also significantly lower than in women with h-PE and si-PE (1.51±0.43 vs. 1.87±0.21 and 1.85±0.32). The incidence rates of the sFlt-1/PlGF ratio ⩾95th percentile of the reference value were 73, 100 and 92%, respectively, (P=0.080), and those of sEng ⩾95th percentile were 67, 100 and 89%, respectively, (P=0.053). In conclusion, the levels of sFlt-1/PlGF ratio and sEng in women with GH were lower than in those with h-PE and with si-PE; however, the majority of women with GH showed abnormal increases of both sFlt-1/PlGF ratio and sEng, suggesting that GH may be a subclinical PE in view of serum levels of angiogenesis-related factors.