Angiopoietin-2 primes infection-induced preterm delivery.

Current knowledge on the participation of angiopoietin-2 (Ang-2) in the inflammatory process and on the importance of bacterial endotoxins (LPS) in the induction of preterm delivery (PTD) led us to investigate the role of Ang-2/LPS interplay in the pathogenesis of PTD. At a first stage, Ang-2 was measured at the end of the first trimester of pregnancy in the serum of 50 women who delivered prematurely; of 88 women well-matched for age and parity who delivered full-term; and of 20 non-pregnant healthy women. Ang-2 was greater in pregnant than in non-pregnant women. The time until delivery was shorter among those with Ang-2 greater than 4 ng/ml (odds ratio for delivery until week 34; p: 0.040). To further investigate the role of Ang-2 for PTD, an experimental model of PTD induced by the intraperitoneal injection of LPS in mice was used. Ang-2 was administered intraperitoneally before LPS on day 14 of pregnancy. When Ang-2 was administered before the LPS diluent, all mice delivered full-term. However, administration of Ang-2 prior LPS accelerated further the time until delivery. Sacrifice experiments showed that the effect of Ang-2 was accompanied by decrease of the penetration of Evans Blue in the embryos and by increase of its penetration in maternal tissues. In parallel, the concentration of tumour necrosis factor-alpha in the maternal circulation, in fetal tissues and in the placentas was significantly decreased. Results indicate that Ang-2 accelerated the phenomena of PTD induced by LPS. This is related with deprivation of fetal perfusion

Angiopoietin-2 Primes Infection-Induced Preterm Delivery

Current knowledge on the participation of angiopoietin-2 (Ang-2) in the inflammatory process and on the importance of bacterial endotoxins (LPS) in the induction of preterm delivery (PTD) led us to investigate the role of Ang-2/LPS interplay in the pathogenesis of PTD. At a first stage, Ang-2 was measured at the end of the first trimester of pregnancy in the serum of 50 women who delivered prematurely; of 88 women well-matched for age and parity who delivered full-term; and of 20 non-pregnant healthy women. Ang-2 was greater in pregnant than in non-pregnant women. The time until delivery was shorter among those with Ang-2 greater than 4 ng/ml (odds ratio for delivery until week 34; p: 0.040). To further investigate the role of Ang-2 for PTD, an experimental model of PTD induced by the intraperitoneal injection of LPS in mice was used. Ang-2 was administered intraperitoneally before LPS on day 14 of pregnancy. When Ang-2 was administered before the LPS diluent, all mice delivered full-term. However, administration of Ang-2 prior LPS accelerated further the time until delivery. Sacrifice experiments showed that the effect of Ang-2 was accompanied by decrease of the penetration of Evans Blue in the embryos and by increase of its penetration in maternal tissues. In parallel, the concentration of tumour necrosis factor-alpha in the maternal circulation, in fetal tissues and in the placentas was significantly decreased. Results indicate that Ang-2 accelerated the phenomena of PTD induced by LPS. This is related with deprivation of fetal perfusion

Tissue penetration of Evans blue.

<p>Female pregnant female mice were challenged at 14.5 days after plugging with water for injection (WFI, group A, n = 5), with recombinant human angiopoietin-2 (Ang-2 B, n = 5), with lipopolysaccharide of <i>Escherichia coli</i> O55:B5 (LPS, n = 5) and with Ang-2 followed after two hours with LPS (Ang-2+LPS, n = 7). One day after challenge with LPS, mice were sacrificed. Evans blue was measured in the fetuses (panel A), in the placentas (panel B), in the kidneys of mothers (panel C) and in the lungs of mothers (panel D). P values indicate statistical significances between the LPS and the LPS+Ang-2 groups.</p

Study flow-chart.

<p>PTD: preterm delivery.</p

The effect of Ang-2 on TNFα.

<p>Pregnant female mice were challenged at 14.5 days after plugging with water for injection (WFI, group A, n = 5), with recombinant human angiopoietin-2 (Ang-2 B, n = 5), with lipopolysaccharide of <i>Escherichia coli</i> O55:B5 (LPS, n = 5) and with Ang-2 followed after two hours with LPS (Ang-2+LPS, n = 7). One day after challenge with LPS, mice were sacrificed. Concentrations of TNFα were measured in the sera of mothers (panel A); in the homogenates of fetuses (panel B); and in the homogenates of the placentas (panel C). P values of statistically comparisons between groups: <u>Comparisons LPS vs WFI </u>^ap<0.0001 LPS vs WFI; ^bp: 0.012. <u>Comparisons LPS vs Ang-2 </u>^cp<0.0001; ^dp: 0.006. <u>Comparisons LPS vs LPS+Ang-2 </u>^ep<0.0001; ^fp: 0.006.</p

Concentrations of Ang-2 during pregnancy.

<p>A) Serum levels of Ang-2 were measured at week 12 in serum of 50 women who delivered prematurely (PTD); of 88 women who delivered full-term; and of 20 non-pregnant healthy women. P values represent comparisons to non-pregnant healthy women. B) Time until delivery in relation with the level of circulating Ang-2 at week 12. P is the value of comparisons between women with serum Ang-2 below and above 4 ng/ml.</p

Ang-2 accelerates preterm delivery (PTD).

<p>Female pregnant female mice were challenged at 14.5 days after plugging with water for injection (WFI, group A, n = 6), with recombinant human angiopoieting-2 (Ang-2 B, n = 6), with lipopolysaccharide of <i>Escherichia coli</i> O55:B5 (LPS, n = 6) and with Ang-2 followed after two hours with LPS (Ang-2+LPS, n = 6). The time until delivery of alive offspring was recorded every two hours after challenge with LPS. Statistical comparisons between groups after correction for multiple testing by Bonferroni were: log-rank_{WFI vs LPS:} 13.679, p: 0.000217; log-rank_{WFI vs LPS+Ang-2}: 15.251, p: 0.000094; log-rank_{LPS vs LPS+Ang-2}: 6.290, p: 0.012.</p