Increase in short telomeres during the third trimester in human placenta.

An increase in telomere shortening in gestational tissues has been proposed as a mechanism involved in the timing for the initiation of parturition. An increase in very short telomeres with increasing gestational age has been observed in mice; this study sought to explore this phenomenon in human pregnancies. Specifically, this study addressed the hypothesis that prior to labor, the quantity of very short telomeres (<3 kilobase (kb) lengths) increases in human placental tissue as term gestation approaches.

Telomeres, oxidative stress, and timing for spontaneous term and preterm labor.

Telomeres are nucleoprotein complexes located at the distal ends of chromosomes. In adults, progressive telomere shortening occurs throughout the lifetime and is thought to contribute to progressive aging, physiological senescence, multiorgan dysfunction, and ultimately, death. As discussed in this review, multiple lines of evidence provide support for the biological plausibility that a telomere-based clock mechanism also determines the length of gestation, leading to the onset of labor (parturition).

Cell-Free Fetal DNA Increases Prior to Labor at Term and in a Subset of Preterm Births.

Cell-free fetal DNA in the maternal circulation has been associated with the onset of labor at term. Moreover, clinical studies have suggested that cell-free fetal DNA has value to predict pregnancy complications such as spontaneous preterm labor leading to preterm birth. However, a mechanistic link between cell-free fetal DNA and preterm labor and birth has not been established.

Modulation of IL10 and Its Receptor Subunits in Normal and Progesterone-Prolonged Gestation in the Mouse.

These experiments aimed to understand the relationship between interleukin 10 (IL10), the IL10 receptor subunits, and progesterone (P4) at the time of parturition. We hypothesized that there is a biologic connection between IL10 and P4, supporting an immunomodulatory mechanism for the onset of labor. Using samples from control and P4-treated pregnant mice, we assessed the production of IL10 and its receptor subunits (IL10Rα and IL10Rβ) in gestational tissues.

The telomere gestational clock: increasing short telomeres at term in the mouse.

Background: The biologic mechanism(s) regulating the length of gestation are currently poorly understood. After peaking at the blastocyst stage, the average telomere lengths have been reported to shorten during the remainder of gestation in the placenta and fetal membranes in both human and mouse pregnancies, thereby providing a potential countdown biologic clock. These previous studies have reported changes in the average telomere lengths, whereas it has now been shown that the shortest telomeres, not the average telomere lengths, are the mediators of telomere dysfunction which limits cellular survival and results in aging.

Cell-Free DNA Release by Mouse Fetal Membranes.

Introduction: Cell-free "fetal" DNA is released from the placenta. Because the fetal membranes also arise from the trophectoderm layer of the blastocyst, these studies sought to test the hypothesis that the membranes also release cell-free DNA (cfDNA).

Methods: Fetal membranes were harvested from pregnant CD-1 mice and cultured in 12-well plates containing media alone or with staurosporine and thapsigargin (apoptosis stimulators), Q-VD-OPh (caspase inhibitor), Trolox (vitamin E analog), and lipopolysaccharide and tumor necrosis factor α (TNFα; inflammatory mediators).

The Effect of Maternal Obesity on Placental Cell-Free DNA Release in a Mouse Model.

Background: The fetal fraction of cell-free DNA (cfDNA) in maternal plasma is decreased in obese women. The underlying mechanism is not well understood. The amount of cfDNA released from the placenta has not been directly examined in maternal obesity.

Fetal and Placental DNA Stimulation of TLR9: A Mechanism Possibly Contributing to the Pro-inflammatory Events During Parturition.

Introduction: While there is evidence for a relationship between cell-free fetal DNA (cffDNA) and parturition, questions remain regarding whether cffDNA could trigger a pro-inflammatory response on the pathway to parturition. We hypothesized that placental and/or fetal DNA stimulates toll-like receptor 9 (TLR9) leading to secretion of pro-inflammatory cytokines by macrophage cells.

Methods: Four in vitro DNA stimulation studies were performed using RAW 264.

Cell-free DNA release by mouse placental explants.

Although suggested that "fetal" cell-free DNA (cfDNA) is derived from trophoblast cells, the exact origin is unclear. The studies in this report sought to demonstrate that placental tissue releases cfDNA in parallel with cell death, that the size range of cfDNA is similar to that found in maternal plasma, and that the cfDNA fragments are able to stimulate a proinflammatory cytokine response. Placentas were harvested from near term pregnant CD-1 mice and cultured in DMEM/Ham's F12/FBS media in 8% or 21% O2.

Estradiol and progesterone influence on influenza infection and immune response in a mouse model.

Problem: Influenza infection severity may be mediated by estradiol and/or progesterone.

Method Of Study: An exploratory study was designed to evaluate 17-β-estradiol and progesterone on influenza infection and examine immune-mediated response in a mouse model. Inoculation with placebo or mouse-adapted H1N1 influenza virus occurred.

Birth and death: Evidence for the same biologic clock.

In mammals, there exists a strong correlation between the average life span (in years) and the length of gestation (in days), suggesting that the same biologic clock mechanisms control both of these physiologic events. Life span is determined by a complex sequence of events leading to organismal senescence, and ultimately death. Although multiple biochemical and cellular phenomena are believed to be involved, progressive telomere shortening due to oxidative stress and loss during DNA replication is believed to be an important determinant contributing to aging, senescence, and adult death.

Hormone Modulation of Toll-Like Receptor 5 in Cultured Human Bladder Epithelial Cells.

Aim: The effect of hormone levels on the stimulation of Toll-like receptor 5 (TLR5) in the bladder is unknown. We aimed to study the effect of estradiol and progesterone on TLR5 expression and function in human bladder epithelial cells.

Methods: After growing to near confluence, T24 human urinary bladder (HUB) cells were incubated in hormone-free (HF) media for 72 hours.

Cell-Free Fetal DNA, Telomeres, and the Spontaneous Onset of Parturition.

Multiple previous reports have provided compelling support for the premise that spontaneous parturition is mediated by activation of inflammation-related signaling pathways leading to increased secretion of cytokines and chemokines, the influx of neutrophils and macrophages into the pregnant uterus, increased production of uterine activation proteins (eg, connexin-43, cyclo-oxygenase-2, oxytocin receptors, etc), activation of matrix metalloproteinases, and the release of uterotonins leading to cervical ripening, membrane rupture, and myometrial contractions. The missing link has been the fetal/placental signal that triggers these proinflammatory events in the absence of microbial invasion and intrauterine infection. This article reviews the biomedical literature regarding the increase in cell-free fetal DNA (cffDNA), which is released during apoptosis in the placenta and fetal membranes at term, the ability of apoptosis modified vertebrate DNA to stimulate toll-like receptor-9 (TLR9) leading to increased release of cytokines and chemokines, and the potential "fail-safe" role for the anti-inflammatory cytokine IL-10.

Molecular Regulation of Parturition: The Role of the Decidual Clock.

The timing of birth is a critical determinant of perinatal outcome. Despite intensive research, the molecular mechanisms responsible for the onset of labor both at term and preterm remain unclear. It is likely that a "parturition cascade" exists that triggers labor at term, that preterm labor results from mechanisms that either prematurely stimulate or short-circuit this cascade, and that these mechanisms involve the activation of proinflammatory pathways within the uterus.

Influenza, immune system, and pregnancy.

Influenza is a major health problem worldwide. Both seasonal influenza and pandemics take a major toll on the health and economy of our country. The present review focuses on the virology and complex immunology of this RNA virus in general and in relation to pregnancy.

Phospholipid scramblase expression in the pregnant mouse uterus in LPS-induced preterm delivery.

Phospholipid scramblases (PLSCR), stimulated by proinflammatory cytokines, are thought to mediate the loss of lipid asymmetry in cell membranes, allowing for specific reactions in the coagulation cascade. The PLSCR may therefore provide a link between inflammation, coagulation, and, because thrombin is a uterotonic, preterm birth (PTB). To explore the relationship between PLSCR expression and inflammation-related PTB, we utilized reverse transcriptase-polymerase chain reaction and Western blot studies to quantify messenger RNA (mRNA) and protein expression for the 4 PLSCR homologues (PLSCR 1-4).

Expression of coagulation-related protein genes during LPS-induced preterm delivery in the pregnant mouse.

Preterm delivery (PTD) has been associated with inflammation along with activation of the coagulation pathway. These studies sought to characterize the expression of several coagulation pathway genes including plasminogen activator inhibitor 1 (PAI-1), tissue factor (TF), protease-activated receptor 1 (Par1), protease-activated receptor 2 (Par2), fibrinogen-like protein 2 (Fgl2), and thrombomodulin (TM) during lipopolysaccharide (LPS)-induced PTD in day 15 pregnant CD-1 mice. Western blot studies confirmed protein expression for PAI-1, Par1, Par2, Fgl2, and TM in the mouse uterus.

Role of nonreceptor protein tyrosine kinases during phospholipase C-gamma 1-related uterine contractions in the rat.

Activated phospholipase C1, produced in response to tyrosine phosphorylation, appears to play an important role during uterine contractions. These studies sought to determine which non-receptor protein tyrosine kinases are involved in the activation of phospholipase C1 in rat uterine tissue. In vitro contraction studies were performed utilizing isoform specific protein tyrosine kinase inhibitors.

Resistance to lipopolysaccharide-induced preterm delivery mediated by regulatory T cell function in mice.

Intrauterine or intraperitoneal administration of lipopolysaccharide (LPS) into normal mice at midgestation induces preterm delivery (PTD) within 24 h through a mechanism dependent on Toll-like receptor signaling and expression of inflammatory cytokines. The exact participants in the cellular network involved in PTD are not known. Although the activities of innate immune cells are thought to be important, the extent to which this process depends on T and B cells has yet to be examined.

Modulation of monocyte chemotactic protein-1 expression during lipopolysaccharide-induced preterm delivery in the pregnant mouse.

Preterm delivery is often associated with increased cytokine and chemokine production. These studies characterize the expression of the chemokine monocyte chemotactic protein-1 (MCP-1) in mice during lipopolysaccharide (LPS)-induced preterm delivery. Uterine and other tissues were harvested from CD-1 mice on gestational day 15 after intrauterine LPS injection.

The role of phospholipase Cgamma1 tyrosine phosphorylation during phasic myometrial contractions.

Objective: Phospholipase Cgamma1 (PLCgamma1) is expressed in myometrium and is activated by tyrosine phosphorylation. These studies sought to determine the association between PLCgamma1 tyrosine phosphorylation and spontaneous uterine contractions.

Study Design: In vitro contraction studies were performed with spontaneously contracting rat uterine strips along with strips that were treated with potassium bisperoxo(1,10 phenanthroline)oxovanadate (bpV(phen), a protein tyrosine phosphatase inhibitor.

Tissue prothrombinase activity in myometrium from timed-pregnant rats.

Objective: Fgl2 and thrombin potentially play roles during inflammation-induced preterm delivery. These studies sought to demonstrate functional prothrombinase enzyme activity in rat uterus, consistent with the expression of Fgl2 in this tissue.

Methods: Myometrial and other tissue obtained from non-pregnant and timed-pregnant rats was homogenized in Tris-buffered saline.