Source of angiopoietin-2 in the sera of women during pregnancy

Angiogenic factors and the lectin pathway of complement in women with secondary recurrent pregnancy loss

The poor remodeling of placental spiral arteries seen in preeclampsia is also discussed to contribute to recurrent pregnancy loss (RPL) preceded by abnormal angiogenesis and excessive complement activation. Low levels of Mannose-binding-lectin (MBL), a pattern recognition molecule (PRM) of the lectin pathway, have been found in women with RPL. We propose that pregnancy loss is connected to defective angiogenesis with reperfusion damage in the placenta and decreased levels of PRM in the lectin pathway in women with RPL. In this cohort study, we investigate the angiogenic factors and the lectin complement pathway in early pregnancy and their time-dependent relationship with pregnancy outcomes in 76 women with secondary RPL (sRPL) who have at least four prior pregnancy losses and a live birth. We evaluated levels of Angiopoietin-1 (Ang-1), Angiopoietin-2 (Ang-2), Vascular Endothelial Growth Factor (VEGF), soluble fms-like tyrosine kinase-1 (sFlt-1), and the PRMs, MBL, ficolin-1, -2, -3 and an additional soluble PRM, Pentraxin-3, during the 5th, 6th, and 7th gestational weeks. Our results showed that, compared to live births, pregnancies that ended in loss were associated with elevated VEGF levels and decreased levels of the Ang-2/Ang-1 ratio. Also, increasing levels of ficolin-2 were significantly associated with pregnancy loss, with MBL showing no association. Our research suggests that women with sRPL may have inadequate placentation with impaired angiogenesis in pregnancies ending in a loss.

Relationship between second-trimester amniotic fluid and plasma levels of angiopoietin-2 and thrombomodulin with adverse pregnancy outcome

Our objective is to investigate maternal midtrimester plasma and amniotic fluid (AF) levels of angiopoietin-2 (Ang-2) and thrombomodulin (TM), which are involved in vascular remodelling and endothelium activation, in placental disorders including foetal growth restriction (FGR) and preeclampsia (PE). This prospective multiparametric pilot study was conducted at the Perinatology Division of Trakya University in a population undergoing genetic amniocentesis. Both AF and plasma aliquots were kept in -80 °C until ELISA assay. The pregnancies were followed up until the end of gestation in terms of obstetric results. Amniotic fluid and plasma aliquots from 127 pregnancies who underwent genetic amniocentesis between 16 and 24 weeks of gestation were analysed. During the final data evaluation, 39 were excluded with various reasons. Twelve subsequently developed FGR and 11 complicated with PE. The control group (n = 65) was consisted of women delivered >37th week with an uncomplicated outcome. The midtrimester maternal Ang-2 levels in both AF and plasma and also TM levels in plasma were found to be significantly increased in pregnancies who subsequently developed FGR or PE (p< .05). The midtrimester Ang-2, which rises in both plasma and AF and the midtrimester TM, which only significantly increase in plasma compartment in PE group, as compensatory mechanism may be the precursors of placental disorders including FGR and PE.Impact StatementWhat is already known on this subject? It is known that angiopoietin-2 (Ang-2) has important role in placental angiogenesis and vascular remodelling. TM which is a receptor for Ang-2 plays a protective role in pregnancy by preventing the uteroplacental circulation from thrombosis.What do the results of this study add? The present study demonstrates that both midtrimester maternal plasma Ang-2/TM and amniotic fluid (AF) Ang-2 levels were significantly higher in PE and FGR group than uncomplicated group. Midtrimester AF TM levels were not significantly higher in PE group than the control group.What the implications are of these findings for clinical practice and/or further research? In the clinical practice, high levels of midtrimester Ang-2 and TM in plasma may be used for the prediction of FGR and PE. Although amniocentesis is not practical in the clinical use, the levels of these two markers in both AF and plasma compartments may contribute to explain the pathophysiology of FGR and PE.

Investigation on the ability of first trimester glycodelin and angiopoietin-2 to predict small-for-gestational age pregnancies at delivery

BACKGROUND

The aim was to investigate whether first trimester glycodelin and angiopoietin-2 can predict small-for-gestational age (SGA) at delivery, individually or in combination.

METHODS

In this case-control study we measured glycodelin and angiopoietin-2 on serum from 170 singleton pregnant women delivering SGA neonates and 985 singleton pregnant women delivering normal-weighted neonates. All values were converted to multiples of the medians (MoM).

RESULTS

Pregnant women delivering SGA neonates had lower first trimester glycodelin and angiopoietin-2 MoM values [median (interquartile range)] compared with pregnant women delivering normal-weighted neonates for glycodelin: 0.86 (0.58-1.24) vs. 1.03 (0.74-1.45), p<0.001, and for angiopoietin-2: 0.89 (0.69-1.19) vs. 1.01 (0.78-1.31), p<0.001. The prediction performances of the biomarkers showed that the areas under the curve (AUC) were 0.59 (glycodelin), 0.58 (angiopoietin-2), and 0.60 (glycodelin and angiopoietin-2).

CONCLUSIONS

We demonstrated that first trimester glycodelin and angiopoietin-2 were associated with SGA, but they were, individually and in combination, poor predictors of SGA at delivery. The AUCs were low which indicate low detection rates and high false positive rates.

Role for the thromboxane A2 receptor β-isoform in the pathogenesis of intrauterine growth restriction

Intrauterine growth restriction (IUGR) is a pathology of pregnancy that results in failure of the fetus to reach its genetically determined growth potential. In developed nations the most common cause of IUGR is impaired placentation resulting from poor trophoblast function, which reduces blood flow to the fetoplacental unit, promotes hypoxia and enhances production of bioactive lipids (TXA₂ and isoprostanes) which act through the thromboxane receptor (TP). TP activation has been implicated as a pathogenic factor in pregnancy complications, including IUGR; however, the role of TP isoforms during pregnancy is poorly defined. We have determined that expression of the human-specific isoform of TP (TPβ) is increased in placentae from IUGR pregnancies, compared to healthy pregnancies. Overexpression of TPα enhanced trophoblast proliferation and syncytialisation. Conversely, TPβ attenuated these functions and inhibited migration. Expression of the TPβ transgene in mice resulted in growth restricted pups and placentae with poor syncytialisation and diminished growth characteristics. Together our data indicate that expression of TPα mediates normal placentation; however, TPβ impairs placentation, and promotes the development of IUGR, and represents an underappreciated pathogenic factor in humans.

Angiopoietin 1 and 2 serum concentrations in first trimester of pregnancy as biomarkers of adverse pregnancy outcomes

OBJECTIVE

To assess angiopoietin-1 (Ang-1), angiopoietin-2 (Ang-2), and the Ang-1/Ang-2 ratio levels in the first trimester of pregnancy, their association with adverse pregnancy outcomes, and their predictive accuracy.

STUDY DESIGN

This cohort study measured serum Ang-1 and Ang-2 levels in 4785 women with singleton pregnancies attending first trimester screening in New South Wales, Australia. Multivariate logistic regression models were used to assess the association and predictive accuracy of serum biomarkers with subsequent adverse pregnancy outcomes (small for gestational age, preterm birth, preeclampsia, miscarriage >10 weeks, and stillbirth).

RESULTS

Median (interquartile range) levels for Ang-1, Ang-2, and the Ang-1/Ang-2 ratio for the total population were 19.6 ng/mL (13.6-26.4), 15.5 ng/mL (10.3-22.7), and 1.21 (0.83-1.73), respectively. Maternal age, weight, country of birth, and socioeconomic status significantly affected Ang-1, Ang-2, and the Ang-1/Ang-2 ratio levels. After adjusting for maternal and clinical risk factors, women with low Ang-2 levels (<10th percentile) and high Ang-1/Ang-2 ratio (>90th percentile) had increased risk of developing most adverse pregnancy outcomes. Compared with the Ang-1/Ang-2 ratio alone, maternal and clinical risk factors had better predictive accuracy for most adverse pregnancy outcomes. The exception was miscarriage (Ang-1/Ang-2 ratio area under receiver operating characteristic curve = 0.70; maternal risk factors = 0.58). Overall, adding the Ang-1/Ang-2 ratio to maternal risk factors did not improve the ability of the models to predict adverse pregnancy outcomes.

CONCLUSION

Our findings suggest that the Ang-1/Ang-2 ratio in first trimester is associated with most adverse pregnancy outcomes, but do not predict outcomes any better than clinical and maternal risk factor information.

Serum angiopoietin-2 and β-hCG as predictors of prolonged uterine bleeding after medical abortion in the first trimester

OBJECTIVE

The combination of mifepristone and misoprostol is an established method for induction of early first trimester abortion, but there is no consensus about the best evaluation of treatment outcome. We evaluate serum Angiopoietin-2 (Ang-2) and β human chorionic gonadotropin (β-hCG) in women who had undergone a medical abortion as markers of prolonged uterine bleeding (PUB).

METHODS

Prospective trial involving 2843 women attending an gynecology outpatient clinic who following a medical abortion with mifepristone and misoprostol, the study cohort was divided into women with duration of uterine bleeding >14 days (PUB) and women with duration of uterine bleeding ≤14 days (normal uterine bleeding, NUB). Serum determinations of Ang-2 levels by ELISA and β-hCG levels by electrochemiluminiscence immunoassay. Receiver Operating Characteristics (ROC) analyses were calculated and plotted for the diagnostic accuracy of serum β-hCG and Ang-2 concentration to discriminate PUB and NUB.

RESULTS

Baseline characteristics for both groups were similar, Only duration of bleeding showed a significant difference between the PUB group and NUB group. Ang-2 serum levels moderately correlated with serum β-hCG levels with statistically significant correlation coefficients of 0.536. Serum β-hCG and Ang-2 levels on day 7 and on day 14 after medical abortion were signifcantly higher in PUB group than in NUB group. Plotted as ROC curves, β-hCG area under curve (AUC) was 0.65 (95% CI, 0.53-0.76) on day 7, rising to AUC = 0.83 (95% CI, 0.75-0.92) on day 14. Using Ang-2 on day 7 and day 14 as predictive parameter resulted in an analogous AUC (AUC = 0.61 on day 7, AUC = 0.78 on day 14).

CONCLUSIONS

Both parameters are clinically useful as a diagnostic test in predicting PUB after medical abortion, and can be helpful in uncertain clinical situations, but should be considered as supplementary to a general clinical evaluation.