endothelin-1 and Premature-Birth

Preterm birth (PTB), defined as birth before 37 completed weeks of gestation, occurs in up to 18 percent of births worldwide and accounts for the majority of perinatal morbidity and mortality. While the single most common cause of PTB has been identified as inflammation, safe and effective pharmacotherapy to prevent PTB has yet to be developed.. Our group has used an in vivo model of inflammation-driven PTB, biochemical methods, pharmacological approaches, a novel endothelin receptor antagonist that we synthesized and RNA knockdown to help establish the role of endothelin-1 (ET-1) in inflammation-associated PTB. Further, we have used our in vivo model to test whether sphingosine kinase, which acts downstream of ET-1, plays a role in PTB.. We have shown that levels of endothelin converting enzyme-1 (ECE-1) and ET-1 are increased when PTB is induced in timed pregnant mice with lipopolysaccharide (LPS) and that blocking ET-1 action, pharmacologically or using ECE-1 RNA silencing, rescues LPS-induced mice from PTB. ET-1 activates the sphingosine kinase/sphingosine-1-phosphate (SphK/S1P) pathway. S1P, in turn, is an important signaling molecule in the proinflammatory response. Interestingly, we have shown that SphK inhibition also prevents LPS-induced PTB in timed pregnant mice. Further, we showed that SphK inhibition suppresses the ECE-1/ET-1 axis, implicating positive feedback regulation of the SphK/S1P/ECE-1/ET-1 axis.. The ET-1/SphK/SIP pathway is a potential pharmacotherapeutic target for the prevention of PTB.

Topics: Animals; Endothelin-1; Female; Humans; Inflammation; Lipopolysaccharides; Lysophospholipids; Mice; Phosphotransferases (Alcohol Group Acceptor); Pregnancy; Premature Birth; Sphingosine

Placental blood vessels play important roles in maternal-fetal circulation. Although pathologic mechanisms of preeclampsia are unclear, it is known that placental vascular dysfunction could contribute to pregnant hypertension. However, placental micro-vessel function or dysfunction at preterm has not been investigated.. Human placentas from normal and preeclamptic pregnancies at preterm and term were obtained. Placental micro-vessels were used for determining vascular tension and responses to various vasoconstrictors as well as intracellular calcium store capability. It was the first time to show vascular responses in placental arteries to angiotensin II, endothelin-1, and other vascular drugs at preterm.. Compared to the control, placental vascular contractile responses to angiotensin II and caffeine were significantly decreased, while placental vascular responses to KCl, endothelin-1, and bradykinin were not significantly altered in the later term group in preeclampsia. In comparison of placental micro-vessel tension between the preterm and later term, caffeine- and serotonin-induced vascular contractions were significantly weaker in the preterm than that in the later term. On the contrary, vascular response to angiotensin II was increased in the preterm preeclampsia, while KCl-, endothelin-1, and bradykinin-mediated placental vessel responses in the preterm preeclampsia were similar to that in later term preeclampsia.. New data showed that micro-vessel responses to angiotensin II and serotonin, not endothelin- 1 or bradykinin, were significantly reduced in the human placentas at preterm, and intracellular Ca2+ store capacity was damaged too, providing important information on possible contributions of placental vascular dysfunction to pregnant hypertension.

Topics: Angiotensin II; Arteries; Endothelin-1; Female; Humans; In Vitro Techniques; Infant, Newborn; Microvessels; Placenta; Pre-Eclampsia; Pregnancy; Premature Birth; Serotonin; Term Birth; Vasoconstriction; Vasoconstrictor Agents

Endogenous uterine agonists can activate numerous signaling pathways to effect increased force. Our objective was to assess expression of key constituents of these pathways, in alliance with contractile function, through late gestation and during term and preterm labor.. Using myography, we measured the response to 3 agonists compared with depolarization alone (K(+), 124 mEq/L) and calculated agonist/depolarization ratio. We measured gene expression using quantitative reverse transcription-polymerase chain reaction.. Contractile responsiveness to depolarization alone, oxytocin, or endothelin-1 increased during pregnancy compared with nonpregnant animals. The agonist/depolarization ratio did not change during uterine activation or parturition. Inhibition of rhoA-associated kinase decreased responses to oxytocin in all tissues, but significantly more during uterine activation. Expression of rhoA and rhoA-associated kinase was increased significantly in active labor at term or preterm.. The rhoA/rhoA-associated kinase pathway is a key regulator of uterine activation during labor and may be a useful target for the prevention of spontaneous preterm birth.

Topics: Animals; Endothelin-1; Female; Models, Animal; Myography; Oxytocin; Parturition; Potassium; Pregnancy; Premature Birth; Rats; Reverse Transcriptase Polymerase Chain Reaction; rho-Associated Kinases; rhoA GTP-Binding Protein; Uterine Contraction

To evaluate plasma endothelin-1 (ET-1) and fetuin-A concentrations in women with intrahepatic cholestasis of pregnancy (ICP) and to determine whether there is any association between these parameters and fetal asphyxia.. We carried out a prospective case-control study consisting of 32 women with ICP at third trimester of pregnancy and 32 pregnant women without ICP. Blood samples from maternal peripheral venous circulation were collected and ET-1 and fetuin-A levels were determined from the plasma samples. Pulse-wave Doppler and Apgar scores were also recorded.. ET-1 concentrations were significantly higher in ICP patients. No difference was observed in fetuin-A levels between the two groups. Six newborns were declared as asphyctic (APGAR score at the 5 min <7). Maternal ET-1 levels did not correlate with the APGAR score at 5 min, total bile acid (TBA) and umbilical artery systolic/diastolic ratio with ICP patients. TBA levels were positively correlated with umbilical artery systolic/diastolic ratio negatively correlated with APGAR score at the 1' and 5'-Apgar score in all subjects. Plasma ET-1 concentration was higher in the preterm neonates of mothers with ICP compared with normal term neonates of mothers.. Although these data did not show evidence that maternal ET-1 would be associated with fetal distress, we can speculate that maternal ET-1 may be playing a role in the underlying pathology regarding microvascular dysfunction especially in the preterm neonates of mothers with ICP. Elevated TBA levels may increase the risk of asphyxia whereas fetuin-a (as an anti-inflammation marker) does not seem to have effect in women with ICP.

Topics: Adolescent; Adult; alpha-2-HS-Glycoprotein; Apgar Score; Asphyxia Neonatorum; Blood Proteins; Case-Control Studies; Cholestasis, Intrahepatic; Endothelin-1; Female; Fetal Distress; Humans; Infant, Newborn; Laser-Doppler Flowmetry; Pregnancy; Pregnancy Complications; Premature Birth; Prospective Studies; Umbilical Arteries; Young Adult

Preterm birth (PTB) currently accounts for 13% of all births in the United States, with the leading cause of PTB being maternal infection. Endothelin-1, an extremely potent vasoconstrictor capable of increasing myometrial smooth muscle tone, has been shown to be up-regulated in the setting of infection in pregnancy, ultimately leading to PTB. In previous work, we have shown that infection-associated PTB is controlled in our murine model by using phospharamidon, an endothelin-converting enzyme-1 inhibitor; knocking down endothelin-converting enzyme-1 mRNA; or blocking the binding of endothelin-1 to the endothelin-A (ET(A)) receptor with either BQ-123 or with HJP-272, the 6-OH compound of our series of novel synthetic (ET(A)) receptor antagonists. In the current study, we show that HJP-272, a highly selective ET(A) receptor antagonist with an IC(50) of 70.1 nmol/L, binds in a noncompetitive manner to the ET(A) receptor. Additionally, we introduce n-propyl (HJP-286) and n-butyl (HJP-278) analogs of HJP-272. We find that the LD(50) of HJP-272, the analog in the series most effective in controlling preterm birth, is more than 20-fold higher than its therapeutic dose. Acute exposure to high doses of these compounds produces no histological changes in any organ, while chronic exposure produces only a rare hepatotoxic effect. These findings may be of clinical significance, as there is currently no FDA-approved therapy for women presenting with threatened preterm delivery.

Topics: Animals; Aspartic Acid Endopeptidases; Benzodioxoles; Binding, Competitive; Endothelin A Receptor Antagonists; Endothelin-1; Endothelin-Converting Enzymes; Female; Hydroxyquinolines; Lipopolysaccharides; Metalloendopeptidases; Mice; Mice, Inbred C57BL; Pregnancy; Pregnancy Complications, Infectious; Pregnancy, Animal; Premature Birth; Quinolones; Receptor, Endothelin A; Swine

Premature delivery occurs in 12% of all births and accounts for nearly half of long-term morbidity. Current therapeutic approaches to preterm delivery are ineffective and present serious risks to both mother and fetus. The single most common cause of preterm birth is infection. Previous in vitro investigations have shown that endothelin-1 (ET-1) is induced by inflammatory cytokines and that it increases myometrial smooth muscle tone. Furthermore, we have previously shown that both the endothelin-converting enzyme-1 (ECE-1) inhibitor, phosphoramidon, as well as a novel ET-1 receptor A antagonist synthesized by our group, control premature delivery in a mouse model of inflammation-associated preterm delivery. In the current work, we show that levels of both ET-1 and ECE-1 are increased in gestational tissues in E16.5 mice induced to deliver prematurely after lipopolysaccharide administration. We also show that premature delivery is controlled by treatment with the selective endothelin receptor A antagonist BQ-123 in a dose-dependent manner. Finally, we show here for the first time that premature delivery can be controlled using RNA silencing, by hydrodynamic transfection of E15 mice with ECE-1 RNAi. Taken together, these data support a critical role for the ECE-1/ET-1 system in inflammation-associated premature delivery. The ability to control premature delivery by antagonizing or silencing the ECE-1/ET-1 system offers a novel approach to an unmet clinical need.

Topics: Animals; Aspartic Acid Endopeptidases; Endothelin A Receptor Antagonists; Endothelin-1; Endothelin-Converting Enzymes; Female; Immunohistochemistry; Inflammation; Lipopolysaccharides; Metalloendopeptidases; Mice; Mice, Inbred C57BL; Models, Animal; Obstetric Labor, Premature; Peptides, Cyclic; Placenta; Pregnancy; Premature Birth; RNA, Small Interfering; Uterus