Effect of thrombin on human amnion mesenchymal cells, mouse fetal membranes, and preterm birth

Here, we investigated the effects of thrombin on matrix metalloproteinases (MMPs) and prostaglandin (PG) synthesis in fetal membranes. Thrombin activity was increased in human amnion from preterm deliveries. Treatment of mesenchymal, but not epithelial, cells with thrombin resulted in increased MMP-1 and MMP-9 mRNA and enzymatic activity. Thrombin also increased COX2 mRNA and PGE2 in these cells. Protease-activated receptor-1 (PAR-1) was localized to amnion mesenchymal and decidual cells. PAR-1-specific inhibitors and activating peptides indicated that thrombin-induced up-regulation of MMP-9 was mediated via PAR-1. In contrast, thrombin-induced up-regulation of MMP-1 and COX-2 was mediated through Toll-like receptor-4, possibly through thrombin-induced release of soluble fetal fibronectin. In vivo, thrombin-injected pregnant mice delivered preterm. Mmp8, Mmp9, and Mmp13, and PGE2 content was increased significantly in fetal membranes from thrombin-injected animals. These results indicate that thrombin acts through multiple mechanisms to activate MMPs and PGE2 synthesis in amnion.

Treatment decision-making for post-partum hemorrhage using dynamic contrast-enhanced computed tomography

AIM

Post-partum hemorrhage (PPH) is the leading cause of maternal mortality. Identification of the precise bleeding site is generally important to control hemorrhage, but such an approach has not been fully established in the context of PPH. We postulated that visualization of bleeding sites could aid treatment decisions in the management of PPH.

METHODS

We conducted a prospective review of 26 patients who underwent dynamic computed tomography (CT) for PPH.

RESULTS

A total of 17 cases presented with uterine bleeding, eight with vaginal hematomas, and one with hemoperitoneum. Overall, dynamic CT identified contrast media extravasation in the arterial phase in 12 of 26 (46.2%) cases: the upper (n = 4) and the lower uterine segment including the cervix (n = 2), subfascial space (n = 1) and vagina (n = 5). Identification of precise arterial bleeding sites using CT provided informative guidance about where to place balloons for intractable uterine bleeding, and how to manage hemoperitoneum and vaginal hematomas. In addition, dynamic CT revealed the existence of a subtype of uterine atony, which is characterized by focal active arterial bleeding in the upper uterine segment. Furthermore, negative contrast extravasation extracted cases of PPH that were well controlled without the need for surgical or radiological intervention. No patient required emergency hysterectomy to control PPH.

CONCLUSION

Dynamic CT has potential clinical utility in treatment decision-making for PPH.

Vaginal delivery in the presence of huge vulvar varicosities: a case report with MRI evaluation

Vulvar varicosities are generally not an indication for a caesarean section but in a rare case of severe vulvar varicosities, it would be a controversial issue whether to perform a caesarean section for fear they might rupture during a vaginal delivery. We present a case of huge vulvar varicosities during pregnancy. MRI revealed obstruction of the internal iliac system by the gravid uterus and subsequent incompetence of a collateral pathway via the round ligament vein that emptied into the ovarian vein. The patient went into labour at 38 weeks, and successfully vaginally delivered a baby. The vulvar varicose veins became compressed by the foetal head from the inside, and markedly diminished in size during crowning and after delivery. Women with vulvar varicosities can be allowed to attempt a vaginal birth regardless of their severity. The use of MRI aids in the overall anatomical understanding of vulvar varicosities in pregnancy.

ATP-binding cassette transporter A1 expression is decreased in preeclamptic placentas

Preeclampsia is a pregnancy-specific multisystem disorder characterized by hypertension and proteinuria. Accentuated maternal hyperlipidemia, especially high serum levels of oxidized low-density lipoprotein (oxLDL), is one of the features of preeclampsia. We previously reported that lectin-like oxidized LDL receptor 1 (LOX-1) expression was decreased in preeclamptic placentas. Here, we show that decreased LOX-1 expression is associated with low expression of adenosine triphosphate-binding cassette transporter A1 (ABCA1) in the placenta. The ABCA1 mediates cellular efflux of cholesterol, and liver X receptors (LXRs) are its predominant transcriptional regulators. Both ABCA1 and LXR expressions were significantly lower in preeclamptic placentas than those in normal controls. Oxidized LDL upregulated ABCA1 expression, while LOX-1 blockade resulted in the alleviation of increasing ABCA1 messenger RNA in JAR cells. These results suggest that low LOX-1 expression may lead to insufficient oxLDL uptake, thereby contributing to reduced LXR activation and decreased ABCA1 expression in preeclamptic placentas.

Fetal fibronectin signaling induces matrix metalloproteases and cyclooxygenase-2 (COX-2) in amnion cells and preterm birth in mice

Fetal fibronectin (fFN) in cervical and vaginal secretions has been used as a predictor of preterm delivery. Here, we clarified the pathological function of fFN on cell type-specific matrix metalloproteinases (MMPs) and prostaglandin synthesis in fetal membranes. Treatment of amnion mesenchymal cells with fFN resulted in dramatic increases in MMP-1 and MMP-9 mRNA and enzymatic activity as well as COX-2 mRNA and prostaglandin E(2) synthesis, activating both NFκB and ERK1/2 signaling. Fetal FN-induced increases in MMPs and COX-2 were mediated through its extra domain A and Toll-like receptor 4 expressed in mesenchymal cells. Lipopolysaccharide and TNF-α increased the release of free FN in medium of amnion epithelial cells in culture. Finally, injection of fFN in pregnant mice resulted in preterm birth. Collectively, these results indicate that fFN is not only a marker of preterm delivery but also plays a significant role in the pathogenesis of preterm labor and premature rupture of fetal membranes.

Decreased lectin-like oxidized LDL receptor 1 (LOX-1) and low Nrf2 activation in placenta are involved in preeclampsia

CONTEXT

Serum concentration of oxidized low-density lipoprotein (oxLDL) is higher in women with preeclampsia than in normal pregnant woman. Lectin-like oxLDL receptor-1 (LOX-1) is one of the scavenger receptors for oxLDL and is abundantly expressed in placenta. It is well known that oxLDL activates nuclear factor erythroid 2-related factor 2 (Nrf2), a master regulator of antioxidant and cytoprotective genes such as heme oxygenase-1 (HO-1), which play an important role in preeclampsia. However, it has yet to be elucidated whether LOX-1, along with Nrf2, participates in the pathology of preeclampsia.

OBJECTIVE

The objective of the study was to assess LOX-1 expression and Nrf2 activation in preeclamptic placentas and to manifest their physiological roles in preeclampsia.

METHODS

Expression and regulation of LOX-1, HO-1, and Nrf2 were evaluated by real-time quantitative RT-PCR and Western blotting. The functions of LOX-1 and Nrf2 were examined using an anti-LOX-1 antibody and Nrf2 activator in JAR, a choriocarcinoma cell line, and placental explants.

RESULTS

Both LOX-1 expression and Nrf2 activation were significantly decreased in preeclamptic placentas compared with normal controls. A significant decrease in LOX-1 mRNA was found in placental explant cultures under hypoxic conditions. Activation of Nrf2 up-regulated HO-1 in both the JAR cells and placental explants. Furthermore, oxLDL increased HO-1 mRNA, whereas the blockade of LOX-1 inhibited the increase of HO-1 mRNA in JAR cells.

CONCLUSION

Decreasing LOX-1 expression in preeclamptic placenta may contribute to high oxLDL concentration, low Nrf2 activation, and low HO-1 expression. These findings provide novel insights into the crucial role of LOX-1 and Nrf2 in the pathogenesis of preeclampsia.

Thioredoxin binding protein-2 inhibits excessive fetal hypoglycemia during maternal starvation by suppressing insulin secretion in mice

Glucose is a major fuel for fetal development. Fetal blood glucose level is mainly dependent on maternal blood glucose concentration, though it is also regulated by fetal insulin level. Thioredoxin binding protein-2 (TBP-2), which is identical to vitamin D3 up-regulated protein (VDUP1) and thioredoxin interacting protein (Txnip), was recently reported to be a key transcriptional factor controlling glucose metabolism. Here, we elucidated the functions of TBP-2 in maintaining blood glucose homeostasis during the fetal period. TBP-2(+/-) female mice were mated with TBP-2(+/-) male mice; beginning 16.5-d post coitum, pregnant mice were fed or fasted for 24 h. Under conditions of maternal starvation, the blood glucose levels of TBP-2(-/-) fetuses were significantly lower than those of TBP-2(+/+) fetuses, corresponding to the elevated plasma insulin levels of TBP-2(-/-) fetuses compared with those of TBP-2(+/+) fetuses. There was no difference between TBP-2(+/+) and TBP-2(-/-) fetuses in terms of their pancreatic beta-cell masses or the expression of placental glucose transporters under conditions of either maternal feeding or fasting. Thus, during maternal fasting, fetal TBP-2 suppresses excessive insulin secretion to maintain the fetus's glucose levels, implying that TBP-2 is a critical molecule in mediating fetal glucose homeostasis depending on nutrient availability.

Isocaloric high-protein diet as well as branched-chain amino acids supplemented diet partially alleviates adverse consequences of maternal undernutrition on fetal growth

Maternal undernutrition causes fetal growth restriction. Protein is a vital dietary nutrient for fetal growth, and branched-chain amino acids (BCAA) are noted to have anabolic actions. In this study, we investigated the effects of maternal high-protein diet or BCAA-supplemented diet upon fetal growth under the condition of maternal calorie restriction. Pregnant mice were calorie-restricted (undernutrition: UN), using either a standard diet (S-UN group), high-protein diet (HP-UN group), or BCAA-supplemented diet (BCAA-UN group) to 70% of the control; dams fed ad libitum with a standard diet (S-NN group) from 10.5days post coitum (dpc) to 18.5dpc. The fetal weights of UN groups were significantly decreased compared to that of S-NN. However, the fetal weights of HP-UN and BCAA-UN were significantly higher by 5% and 4%, respectively, than those of S-UN, concomitant with augmentation of the gene and protein expressions of IGF-I and IGF-II in fetal liver. A high-protein diet as well as BCAA-supplemented diet partially improved fetal growth restriction caused by maternal calorie-restriction, suggesting a pivotal role of them in the amelioration of fetal growth restriction.

Isocaloric high-protein diet ameliorates systolic blood pressure increase and cardiac remodeling caused by maternal caloric restriction in adult mouse offspring

Epidemiologic studies have shown that in utero malnutrition is a risk factor for adult cardiovascular disease (CVD). Recently, we reported a mouse animal model of 30% maternal caloric reduction, in which offspring showed a significant increase in systolic blood pressure (SBP) as well as in cardiac remodeling-associated morphological parameters such as cardiac enlargement and coronary perivascular fibrosis in adulthood. Using a similar animal model, we here demonstrated that an increased level of protein consumption during an undernourished pregnancy (high-protein diet; HPD) corrected for the development of CVD risk factors found in fetal undernourishment with less protein consumption (standard-protein diet; SPD). In contrast, maternal ad libitum feeding with HPD resulted in significantly elevated SBP and cardiac enlargement in offspring at 16 wks. Appropriate maternal protein ingestion might partly protect against the development of CVD risk factors in offspring.

Neonatal exposure to leptin augments diet-induced obesity in leptin-deficient Ob/Ob mice

OBJECTIVE

Epidemiological evidence has revealed that undernutrition in utero is closely associated with obesity and related detrimental metabolic sequelae in adulthood. Recently, using a wild-type (wt) mouse model in which offspring were exposed to intrauterine undernutrition (UN offspring), we reported that the premature leptin surge during neonatal growth promotes lifelong changes in energy regulating circuitry in the hypothalamus, thus playing an important role in the development of pronounced obesity on a high-fat diet (HFD) in adulthood. Here, we further evaluate the essential involvement of leptin in the developmental origins of obesity using leptin-deficient ob/ob mice.

METHODS AND PROCEDURES

We assessed the progression of obesity on an HFD in adult leptin-deficient ob/ob male mice that were exposed to intrauterine undernutrition by maternal food restriction (ob/ob UN offspring) or to leptin treatment during the neonatal period; this treatment is comparable to the premature leptin surge observed in the wt-UN offspring.

RESULTS

On an HFD, the body weight of the male ob/ob UN offspring paralleled that of the ob/ob offspring exposed to normal intrauterine nutrition (ob/ob NN offspring). In contrast, early exposure to leptin in the ob/ob NN offspring during early neonatal growth reproduced the development of pronounced obesity on an HFD in adulthood.

DISCUSSION

The presence of leptin and associated energy regulation are indispensable in the acceleration of obesity on an HFD caused by undernutrition in utero. The premature leptin surge plays an essential role in the developmental origins of obesity as a programming signal during the early neonatal period.

Undernutrition in utero augments systolic blood pressure and cardiac remodeling in adult mouse offspring: possible involvement of local cardiac angiotensin system in developmental origins of cardiovascular disease

Evidence has emerged that undernutrition in utero is a risk factor for cardiovascular disorders in adulthood, along with genetic and environmental factors. Recently, the local expression of angiotensinogen and related bioactive substances has been demonstrated to play a pivotal role in cardiac remodeling, i.e. fibrosis and hypertrophy. The aim of the present study was to clarify the possible involvement of the local cardiac angiotensin system in fetal undernutrition-induced cardiovascular disorders. We developed a mouse model of undernutrition in utero by maternal food restriction, in which offspring (UN offspring) showed an increase in systolic blood pressure (8 wk of age, P < 0.05; and 16 wk, P < 0.01), perivascular fibrosis of the coronary artery (16 wk, P < 0.05) and cardiac cardiomegaly (16 wk, P < 0.01), and cardiomyocyte enlargement, concomitant with a significant augmentation of angiotensinogen (P < 0.05) and endothelin-1 (P < 0.01) mRNA expression and a tendency to increase in immunostaining for both angiotensin II and endothelin-1 in the left ventricles (16 wk). These findings suggest that fetal undernutrition activated the local cardiac angiotensin system-associated bioactive substances, which contributed, at least partly, to the development of cardiac remodeling in later life, in concert with the effects of increase in blood pressure.

Activated protein C attenuates coagulation-associated over-expression of fibrinolytic activity by suppressing the thrombin-dependent inactivation of PAI-1

Several activated coagulation factors have been reported to enhance fibrinolysis by neutralizing plasminogen activator inhibitor type 1 (PAI-1) activity. We evaluated the physiological relevance of this mechanism using the euglobulin clot lysis time (ECLT) assay in the presence and absence of Ca2+, which is controlled by PAI-1 and mimics physiological thrombolysis. We found that the ECLT (18.5 +/- 0.6 h) was shortened by Ca2+ (5 mm) (6.6 +/- 0.1 h). A significant difference was observed in thrombin generation by the presence of Ca2+ in the euglobulin fraction. Prothrombin was almost fully converted to thrombin within 15 min in the presence of Ca2+, whereas essentially no conversion was observed without Ca2+. The presence of activated protein C (aPC) suppressed thrombin generation, and attenuated the shortening of ECLT in a dose-dependent manner, an effect enhanced by phospholipid and protein S. In the absence of Ca2+, aPC did not prolong the ECLT. After addition of biotin-labeled recombinant PAI-1 to the euglobulin fraction, PAI-1 was cleaved to lower molecular weight forms only in the presence of Ca2+. This cleavage did not occur in the presence of aPC, suggesting that thrombin was the catalyst for PAI-1 cleavage. The cleavage and inactivation of PAI-1 by generated thrombin is proposed to be responsible for the shortening of ECLT by Ca2+ and for coagulation-associated over-expression of fibrinolysis. Under such conditions, aPC appeared to suppress thrombin generation and to normalize highly activated fibrinolysis.