Persistence of risk factors associated with maternal cardiovascular disease following aberrant inflammation in rat pregnancy.

INTRODUCTION: Pre-eclampsia is associated with increased risk of subsequent cardiovascular and metabolic disease in the affected mothers. While aberrant inflammation contributes to the pathophysiology of pre-eclampsia, it is unclear whether maternal inflammation contributes to the increased risk of disease. Here, we determined the effect of aberrant inflammation in pregnancy on cardiovascular and metabolic disease risk factors. METHODS: Wistar rats were administered low doses of lipopolysaccharide (LPS) on gestational days (GD) 13.5-16.5 to induce inflammation. Controls included pregnant rats treated with saline and nonpregnant rats treated with LPS or saline. We previously showed that LPS-treated pregnant rats exhibit key features of pre-eclampsia. Echocardiographic parameters, heart weight, blood pressure, blood lipids, pulse-wave velocity, and glucose tolerance, were assessed at 16 weeks postpartum. Messenger RNA levels of transcription factors associated with cardiac growth were measured in left ventricular tissue; histone modifications and global DNA methylation were determined in hearts and livers at GD 17.5 and at 16 weeks postpartum. RESULTS: Compared with saline-treated pregnant rats and nonpregnant rats treated with LPS or saline, LPS-treated pregnant rats exhibited left ventricular hypertrophy and increased blood cholesterol and low-density lipoprotein levels at 16 weeks postdelivery. LPS-treated rats had increased left ventricular mRNA levels of hypertrophy-associated transcription factors at GD 17.5 and increased levels of modified histones in hearts and livers at GD 17.5 and 16 weeks postpartum. Other parameters remained unchanged. CONCLUSION: Aberrant inflammation during pregnancy results in persistent alterations in maternal physiological parameters and epigenetic modifications that could contribute to the pathophysiology of cardiovascular disease.

Spontaneous pregnancy loss mediated by abnormal maternal inflammation in rats is linked to deficient uteroplacental perfusion.

Abnormal maternal inflammation during pregnancy is associated with spontaneous pregnancy loss and intrauterine fetal growth restriction. However, the mechanisms responsible for these pregnancy outcomes are not well understood. In this study, we used a rat model to demonstrate that pregnancy loss resulting from aberrant maternal inflammation is closely linked to deficient placental perfusion. Administration of LPS to pregnant Wistar rats on gestational day 14.5, to induce maternal inflammation, caused fetal loss in a dose-dependent manner 3-4 h later, and surviving fetuses were significantly growth restricted. Pregnancy loss was associated with coagulopathy, structural abnormalities in the uteroplacental vasculature, decreased placental blood flow, and placental and fetal hypoxia within 3 h of LPS administration. This impairment in uteroplacental hemodynamics in LPS-treated rats was linked to increased uterine artery resistance and reduced spiral arteriole flow velocity. Pregnancy loss induced by LPS was prevented by maternal administration of the immunoregulatory cytokine IL-10 or by blocking TNF-α activity after treatment with etanercept (Enbrel). These results indicate that alterations in placental perfusion are responsible for fetal morbidities associated with aberrant maternal inflammation and support a rationale for investigating a potential use of immunomodulatory agents in the prevention of spontaneous pregnancy loss.

Aberrant inflammation in rat pregnancy leads to cardiometabolic alterations in the offspring and intrauterine growth restriction in the F2 generation.

Children of women with pre-eclampsia have increased risk of cardiovascular (CV) and metabolic disease in adult life. Furthermore, the risk of pregnancy complications is higher in daughters born to women affected by pre-eclampsia than in daughters born after uncomplicated pregnancies. While aberrant inflammation contributes to the pathophysiology of pregnancy complications, including pre-eclampsia, the contribution of maternal inflammation to subsequent risk of CV and metabolic disease as well as pregnancy complications in the offspring remains unclear. Here, we demonstrate that 24-week-old female rats (F1) born to dams (F0) exposed to lipopolysaccharide (LPS) during pregnancy (to induce inflammation) exhibited mild systolic dysfunction, increased cardiac growth-related gene expression, altered glucose tolerance, and coagulopathy; whereas male F1 offspring exhibited altered glucose tolerance and increased visceral fat accumulation compared with F1 sex-matched offspring born to saline-treated dams. Both male and female F1 offspring born to LPS-treated dams had evidence of anemia. Fetuses (F2) from F1 females born to LPS-treated dams were growth restricted, and this reduction in fetal growth was associated with increased CD68 positivity (indicative of macrophage presence) and decreased expression of glucose transporter-1 in their utero-placental units. These results indicate that abnormal maternal inflammation can contribute to increased risk of CV and metabolic disease in the offspring, and that the effects of inflammation may cross generations. Our findings provide evidence in support of early screening for CV and metabolic disease, as well as pregnancy complications in offspring affected by pre-eclampsia or other pregnancy complications associated with aberrant inflammation.

Chemosensitization of cancer in vitro and in vivo by nitric oxide signaling.

PURPOSE: Hypoxia contributes to drug resistance in solid cancers, and studies have revealed that low concentrations of nitric oxide (NO) mimetics attenuate hypoxia-induced drug resistance in tumor cells in vitro. Classic NO signaling involves activation of soluble guanylyl cyclase, generation of cyclic GMP (cGMP), and activation of cGMP-dependent protein kinase. Here, we determined whether chemosensitization by NO mimetics requires cGMP-dependent signaling and whether low concentrations of NO mimetics can chemosensitize tumors in vivo. EXPERIMENTAL DESIGN: Survival of human prostate and breast cancer cells was assessed by clonogenic assays following exposure to chemotherapeutic agents. The effect of NO mimetics on tumor chemosensitivity in vivo was determined using a mouse xenograft model of human prostate cancer. Drug efflux in vitro was assessed by measuring intracellular doxorubicin-associated fluorescence. RESULTS: Low concentrations of the NO mimetics glyceryl trinitrate (GTN) and isosorbide dinitrate attenuated hypoxia-induced resistance to doxorubicin and paclitaxel. Similar to hypoxia-induced drug resistance, inhibition of various components of the NO signaling pathway increased resistance to doxorubicin, whereas activation of the pathway with 8-bromo-cGMP attenuated hypoxia-induced resistance. Drug efflux was unaffected by hypoxia and inhibitors of drug efflux did not significantly attenuate hypoxia-induced chemoresistance. Compared with mice treated with doxorubicin alone, tumor growth was decreased in mice treated with doxorubicin and a transdermal GTN patch. The presence of GTN and GTN metabolites in plasma samples was confirmed by gas chromatography. CONCLUSION: Tumor hypoxia induces resistance to anticancer drugs by interfering with endogenous NO signaling and reactivation of NO signaling represents a novel approach to enhance chemotherapy.

Activation of the PD-1/PD-L1 immune checkpoint confers tumor cell chemoresistance associated with increased metastasis.

The ability of tumor cells to avoid immune destruction (immune escape) as well as their acquired resistance to anti-cancer drugs constitute important barriers to the successful management of cancer. Interaction between the Programmed Death Ligand 1 (PD-L1) on the surface of tumor cells with the Programmed Death-1 (PD-1) receptor on cytotoxic T lymphocytes leads to inactivation of these immune effectors and, consequently, immune escape. Here we show that the PD-1/PD-L1 axis also leads to tumor cell resistance to conventional chemotherapeutic agents. Using a panel of PD-L1-expressing human and mouse breast and prostate cancer cell lines, we found that incubation of breast and prostate cancer cells in the presence of purified recombinant PD-1 resulted in resistance to doxorubicin and docetaxel as determined using clonogenic survival assays. Co-culture with PD-1-expressing Jurkat T cells also promoted chemoresistance and this was prevented by antibody blockade of either PD-L1 or PD-1 or by silencing of the PD-L1 gene. Moreover, inhibition of the PD-1/PD-L1 axis using anti-PD-1 antibody enhanced doxorubicin chemotherapy to inhibit metastasis in a syngeneic mammary orthotopic mouse model of metastatic breast cancer. To further investigate the mechanism of tumor cell survival advantage upon PD-L1 ligation, we show that exposure to rPD-1 promoted ERK and mTOR growth and survival pathways leading to increased cell proliferation. Overall, the findings of this study indicate that combinations of chemotherapy and immune checkpoint blockade may limit chemoresistance and progression to metastatic disease.

Moderate Exercise Attenuates Lipopolysaccharide-Induced Inflammation and Associated Maternal and Fetal Morbidities in Pregnant Rats.

Fetal growth restriction (FGR) and coagulopathies are often associated with aberrant maternal inflammation. Moderate-intensity exercise during pregnancy has been shown to increase utero-placental blood flow and to enhance fetal nutrition as well as fetal and placental growth. Furthermore, exercise is known to reduce inflammation. To evaluate the effect of moderate-intensity exercise on inflammation associated with the development of maternal coagulopathies and FGR, Wistar rats were subjected to an exercise regime before and during pregnancy. To model inflammation-induced FGR, pregnant rats were administered daily intraperitoneal injections of E. coli lipopolysaccharide (LPS) on gestational days (GD) 13.5-16.5 and sacrificed at GD 17.5. Control rats were injected with saline. Maternal hemostasis was assessed by thromboelastography. Moderate-intensity exercise prevented LPS-mediated increases in white blood cell counts measured on GD 17.5 and improved maternal hemostasis profiles. Importantly, our data reveal that exercise prevented LPS-induced FGR. Moderate-intensity exercise initiated before and maintained during pregnancy may decrease the severity of maternal and perinatal complications associated with abnormal maternal inflammation.

Inhibition of human trophoblast invasiveness by high glucose concentrations.

CONTEXT: Trophoblast invasion of the uterus is regulated by local microenvironmental factors. OBJECTIVE: Because certain conditions may affect uterine glucose levels during placentation, the aim of this study was to determine the effect of glucose concentration on trophoblast invasion. RESULTS: Compared with incubation in 0.2 and 2.5 mm glucose, a 24-h incubation in increasing glucose concentrations (5 and 10 mm) resulted in up to a 62% inhibition (P < 0.01) of the in vitro invasiveness of immortalized HTR-8/SVneo trophoblasts. This decreased invasiveness in 5 and 10 mm glucose was paralleled by inhibition of a plasminogen activator (PA) activity corresponding to active urokinase-type PA (uPA). Inhibition of pro-uPA binding to the uPA receptor decreased the invasiveness of cells incubated in 0.2 and 2.5 mm glucose to levels observed in cells incubated in higher glucose concentrations (P < 0.05). Gelatin zymography and Western blot analysis revealed that the levels of matrix metalloproteinase-2 and -9, PA inhibitor-1, and uPA receptor were unaffected by glucose. Glucose transporter-1 levels were 26 and 34% higher in cells cultured in 2.5 and 0.2 mm glucose, respectively, vs. 5 or 10 mm glucose (P < 0.05). In contrast, glucose transporter-3 levels were not affected by incubation in various glucose concentrations. CONCLUSIONS: These findings indicate that high glucose concentrations inhibit the invasiveness of HTR-8/SVneo cells by preventing uPA activation. Therefore, through its effects on uPA activity, glucose may be an important regulator of trophoblast invasiveness during implantation and placentation.

Abnormal inflammation leads to maternal coagulopathies associated with placental haemostatic alterations in a rat model of foetal loss.

Spontaneous pregnancy loss is often associated with aberrant maternal inflammation and systemic coagulopathies. However, the role of inflammation in the development of obstetric coagulopathies is poorly understood. Further, questions remain as to whether systemic coagulopathies are linked to placental haemostatic alterations, and whether these local alterations contribute to a negative foetal outcome. Using a model of spontaneous foetal loss in which pregnant rats are given a single injection of bacterial lipopolysaccharide (LPS), we characterised the systemic maternal coagulation status following LPS administration using thromboelastography (TEG), a global haemostatic assay that measures the kinetics of clot formation. Systemic maternal coagulopathy was evident in 82% of LPS-treated rats. Specifically, we observed stage-I, -II, and -III disseminated intravascular coagulation (DIC) and hypercoagulability. Modulation of inflammation through inhibition of tumour necrosis factor α with etanercept resulted in a 62% reduction in the proportion of rats exhibiting coagulopathy. Moreover, inflammation-induced systemic coagulopathies were associated with placental haemostatic alterations, which included increased intravascular, decidual, and labyrinth fibrin deposition in cases of DIC-I and hypercoagulability, and an almost complete absence of fibrin deposition in cases of DIC-III. Furthermore, systemic and placental haemostatic alterations were associated with impaired utero-placental haemodynamics, and inhibition of these haemostatic alterations by etanercept was associated with maintenance of utero-placental haemodynamics. These findings indicate that modulation of maternal inflammation may be useful in the prevention of coagulopathies associated with complications of pregnancy.

Coordinated regulation of human trophoblast invasiveness by macrophages and interleukin 10.

Trophoblast invasion and modification of the spiral arterioles are essential for the establishment of adequate uteroplacental blood flow during pregnancy. However, such vascular remodeling is deficient in preeclampsia. This disease is also associated with increased maternal levels of circulating proinflammatory cytokines such as tumor necrosis factor (TNF) and reduced levels of immunoregulatory cytokines such as interleukin 10 (IL10). We have previously shown that activated macrophages inhibit trophoblast invasiveness in vitro. The present study demonstrates that IL10 interferes with the invasion-inhibitory effect that activated macrophages exert on trophoblast cells. Co-culture experiments revealed that human lipopolysaccharide (LPS)-activated macrophages inhibited the ability of immortalized HTR-8/SVneo human trophoblast cells to invade through reconstituted extracellular matrix. This effect of activated macrophages on trophoblast invasiveness was paralleled by decreased expression of urokinase plasminogen activator receptor (PLAUR) on the surface of trophoblast cells, and by increased secretion of plasminogen activator inhibitor type 1 (SERPINE1). Exposure of LPS-treated macrophages to IL10 prior to co-culture prevented their ability to inhibit trophoblast invasion, PLAUR expression, and to stimulate SERPINE1 secretion. Interleukin 10 prevented macrophage activation by LPS as determined by the lack of secretion of TNF in the culture medium, and a neutralizing TNF antibody completely blocked the effect of macrophages on trophoblast invasion. These results indicate that decreased circulating levels of IL10 associated with preeclampsia may contribute to inadequate trophoblast invasion and remodeling of the uterine spiral arterioles.

Activated macrophages inhibit human cytotrophoblast invasiveness in vitro.

Pre-eclampsia is associated with inadequate cytotrophoblast invasion and remodeling of the uterine spiral arterioles, as well as by an aberrant maternal immune response. This study determined the effect of activated macrophages and one of its products, tumor necrosis factor (TNF)-alpha, on cytotrophoblast invasiveness. Coculture with human lipopolysaccharide-activated macrophages decreased the ability of immortalized HTR-8/ SVneo human trophoblast cells to invade through reconstituted extracellular matrix (P < 0.05). This effect of activated macrophages on trophoblast invasiveness was paralleled by abrogation of a 55-kDa caseinolytic activity corresponding to prourokinase plasminogen activator (pro-uPA) and an increased secretion of plasminogen activator inhibitor 1 (PAI1), as determined by gel zymography and ELISA, respectively. Coculture with nonactivated macrophages did not significantly affect trophoblast invasiveness or pro-uPA and PAI1 secretion. Activated macrophages secreted detectable levels of TNF, and administration of exogenous TNF significantly decreased trophoblast invasiveness (P < 0.05), increased the secretion of PAI1 (P < 0.01), and completely inhibited the pro-uPA-associated caseinolytic activity by binding to the TNF receptor 1. Moreover, addition of up to 10 ng/ml of TNF did not increase the rate of apoptosis in HTR-8/SVneo cells. Finally, the increased secretion of PAI1 by trophoblast cells cocultured with activated macrophages was significantly inhibited when a neutralizing anti-TNF antibody was added to the cocultures. These results suggest that the aberrant presence of activated macrophages around uterine vessels may contribute to inadequate trophoblast invasion and remodeling of the uterine spiral arterioles. Thus, the presence of activated macrophages may be important in the etiology of pre-eclampsia.

Inhibition of breast carcinoma and trophoblast cell invasiveness by vascular endothelial growth factor.

Vascular endothelial growth factor (VEGF) is a potent endothelial cell mitogen and angiogenic growth factor that enhances endothelial cell invasion through the extracellular matrix (ECM). While various cell types express VEGF receptors, little is known about the biological actions of VEGF on nonendothelial cells. Therefore, the main objective of the present study was to determine the effect of VEGF on the in vitro invasiveness and proliferation of human MDA-MB-231 breast carcinoma cells and human HTR-8/SVneo trophoblast cells. Reverse-transcriptase polymerase chain reaction analysis demonstrated the presence of transcripts encoding VEGF receptors (VEGFR) -1, -2, and -3 as well as neuropilins-1 and -2 in the trophoblast cells, and the presence of transcripts encoding VEGFR-2 and neuropilins-1 and -2 in the breast carcinoma cells. Both cell lines also expressed transcripts for VEGF-A, -B, -C and -D, as well as for placenta growth factor (PlGF). Although incubation with exogenous VEGF-A(165) or VEGF-A(121) did not affect the rate of proliferation of either the trophoblast or the breast carcinoma cells, incubation with these molecules reduced their ability to invade through reconstituted ECM (Matrigel). The effect of VEGF-A(165) on the invasiveness of both cell lines was inhibited by the inclusion of a neutralizing antibody to VEGF. Exogenous VEGF-A(165) also decreased the cell surface expression of the urokinase-type plasminogen activator (a molecule required for invasion) by the breast carcinoma and trophoblast cells. These results indicate that the biological actions of VEGF on certain cell types may differ from the effects of this molecule on vascular endothelial cells, and therefore are relevant to angiogenesis-based therapies.