The molecular pathophysiology of bacterially induced preterm labor: insights from the murine model

Peripartum infectious morbidity in women with preeclampsia

BACKGROUND

Dysregulated maternal systemic inflammatory response is a commonly accepted component in the pathogenesis of preeclampsia. Chronic inflammation then occurs characterized by oxidative stress, proinflammatory cytokine production, and abnormal T-cell function. Infection results in similar physiologic changes.

OBJECTIVE

The objective of this study was to examine the association between the diagnosis of preeclampsia and the development of chorioamnionitis, postpartum fever, endometritis and wound infection. We hypothesize that the heightened chronic inflammatory state of preeclampsia increases the risk for maternal peripartum infection.

STUDY DESIGN

This was a retrospective cohort study from the Consortium on Safe Labor (CSL). In the present analysis, we included all women from the CSL database and compared their characteristics and pregnancy outcomes between those with and without a diagnosis of preeclampsia prior to labor. Women presenting with preterm prelabor rupture of membranes or were diagnosed with preeclampsia during labor or postpartum were excluded. The primary outcome was a composite of maternal peripartum infections including intrapartum chorioamnionitis, postpartum fever, endometritis, and wound infection. This outcome was compared between women with and without a diagnosis of preeclampsia prior to labor using univariable and multivariable analyses.

RESULTS

A total of 227,052 women were eligible for the analysis, of these 14,268 (6.3%) were diagnosed with preeclampsia. In univariable analysis, the rate of composite maternal peripartum infection was higher among women with preeclampsia (4.2 versus 3.8%, p = .026). When looking at each individual component, that rates of wound infection (1.0 versus 0.5%, p < .001) and postpartum fever (8.2 versus 4.4%, p < .001) were higher among women with diagnosis of preeclampsia, whereas the rate of intrapartum chorioamnionitis was lower among women with preeclampsia (1.3 versus 1.7% p = .004). Endometritis rates did not differ between the two groups. In multivariable logistic regression, adjusted for confounding variables, including maternal race, insurance status, prepregnancy BMI, maternal age, number of fetuses, number of vaginal exams, intrauterine pressure catheter and fetal scalp electrode placement, mode of delivery, group B streptococcus positivity, maternal education level, induction of labor, prelabor rupture of membranes, tobacco use, presence of diabetes (pregestational and gestational), gestational age at delivery, and chronic hypertension, the association between preeclampsia and composite maternal peripartum infection did not persist. In fact, after controlling for these influences, women with preeclampsia showed lower rates of intrapartum chorioamnionitis (aOR 0.83, 95% CI 0.70-0.99). The rest of the individual component of the primary composite outcome, postpartum fever, endometritis, and wound infection, were not associated with the diagnosis of preeclampsia.

CONCLUSIONS

In this large cohort of women diagnosed with preeclampsia prior to labor, the rate of intrapartum chorioamnionitis was decreased and the rate of postpartum infectious morbidity was not higher compared to women without a diagnosis of preeclampsia.

Interleukin-1 Receptor Modulation Using β-Substituted α-Amino-γ-Lactam Peptides From Solid-Phase Synthesis and Diversification

As a key cytokine mediator of inflammation, interleukin-1β (IL-1β) binds to the IL-1 receptor (IL-1R) and activates various downstream signaling mediators, including NF-κB, which is required for immune vigilance and cellular protection. Toward the development of IL-1-targeting therapeutics which exhibit functional selectivity, the all-D-amino acid peptide 1 (101.10, H-D-Arg-D-Tyr-D-Thr-D-Val-D-Glu-D-Leu-D-Ala-NH₂) was conceived as an allosteric IL-1R modulator that conserves NF-κB signaling while inhibiting other IL-1-activated pathways. Employing β-hydroxy-α-amino-γ-lactam (Hgl) stereoisomers to study the conformation about the Thr³ residue in 1, [(3R,4S)-Hgl³]-1 (2b), among all possible diastereomers, was found to exhibit identical in vitro and in vivo activity as the parent peptide and superior activity to the α-amino-γ-lactam (Agl) counterpart. Noting the relevance of the β-hydroxyl substituent and configuration for the activity of (3R,4S)-2b, fifteen different β-substituted-Agl³ analogs of 1 (e.g., 2c-q) have now been synthesized by a combination of solution- and solid-phase methods employing N-Fmoc-β-substituted-Agl³-Val-OH dipeptide building blocks. Introduction of a β-azido-Agl³ residue into the resin bound peptide and subsequent reduction and CuAAC chemistry gave access to a series of amine and triazole derivatives (e.g., 2h-q). β-Substituted-[Agl³]-1 analogs 2c-q exhibited generally similar circular dichroism (CD) spectra as that of Hgl analog 2b in water, presenting curve shapes indicative of β-turn structures. The relevance of the β-substituent was indicated in rodent models of preterm labor and retinopathy of prematurity (ROP), in which certain analogs inhibited preterm birth and vaso-obliteration, respectively, with activity similar to 1 and 2b. The β-substituted-[Agl³]-1 analogs exhibited functional selectivity on IL-1-induced signaling pathways. The described solid-phase method has provided discerning probes for exploring peptide structure-activity relationships and valuable leads for developing prototypes to treat inflammatory events leading to prematurity and retinopathy of prematurity, which are leading causes of infant morbidity and blindness respectively.

Role of IRG1 in Regulating Pro-inflammatory and Pro-labor Mediators in Human Myometrium

Preterm birth is a major contributor to neonatal deaths and associated long-term morbidities for the survivors, yet therapies remain elusive, given our incomplete understanding of the mechanisms driving human labor and delivery. Human labor is an inflammatory process, and we investigated whether IRG1 (immunoresponsive gene-1) plays a role in these processes. We demonstrate that IRG1 mRNA and protein expression is significantly increased in myometrium with human term labor, compared to no labor samples, and with preterm (LPS) labor in a mouse model. Pro-labor mediators such as pro-inflammatory cytokines TNF and IL1B, and TLR ligands fsl-1, flagellin, LPS, and poly(I:C) also increased IRG1 mRNA expression in myometrial explants. IRG1 silencing, using siRNA in primary myometrial cells, displayed a decrease in the expression of inflammation-induced pro-inflammatory cytokines (IL1A, IL6), chemokines (CCL2, CXCL1, CXCL8), adhesion molecules (ICAM1, VCAM1), and contractility (PTGFR mRNA expression, prostaglandin F_2α release, and in situ gel contraction assay). Our results suggest that IRG1 is involved when pro-labor mediators activate the inflammatory processes of human labor, warranting further investigation.

From germ cells to neonates: the beginning of life and the KEAP1-NRF2 system

The Kelch-like ECH-associated protein 1(KEAP1)-NF-E2-related factor 2 (NRF2) system is one of the most studied environmental stress response systems. In the presence of oxidative and electrophilic insults, the thiols of cysteine residues in KEAP1 are modified, and subsequently stabilized NRF2 activates its target genes that are involved in detoxification and cytoprotection. A myriad of recent studies has revealed the broad range of contributions of the KEAP1-NRF2 system to physiological and pathological processes. However, its functions during gametic and embryonic development are still open for investigation. Although oxidative stress is harmful for embryos, Nrf2-/- mice do not show any apparent morphological abnormalities during development, probably because of the compensatory antioxidant functions of NF-E2-related factor 1 (NRF1). It can also be considered that the antioxidant system is essential for protecting germ cells during reproduction. The maturation processes of germ cells in both sexes are affected by Nrf2 mutation. Hence, in this review, we focus on the stress response system related to reproduction and embryonic development through the functions of the KEAP1-NRF2 system.

Compartmentalized profiling of amniotic fluid cytokines in women with preterm labor

Objective

Amniotic fluid cytokines have been implicated in the mechanisms of preterm labor and birth. Cytokines can be packaged within or on the surface of extracellular vesicles. The main aim of this study was to test whether the protein abundance internal to and on the surface of extracellular vesicles changes in the presence of sterile intra-amniotic inflammation and proven intra-amniotic infection in women with preterm labor as compared to the women with preterm labor without either intra-amniotic inflammation or proven intra-amniotic infection.

Study design

Women who had an episode of preterm labor and underwent an amniocentesis for the diagnosis of intra-amniotic infection or intra-amniotic inflammation were classified into three groups: 1) preterm labor without either intra-amniotic inflammation or proven intra-amniotic infection, 2) preterm labor with sterile intra-amniotic inflammation, and 3) preterm labor with intra-amniotic infection. The concentrations of 38 proteins were determined on the extracellular vesicle surface, within the vesicles, and in the soluble fraction of amniotic fluid.

Results

1) Intra-amniotic inflammation, regardless of detected microbes, was associated with an increased abundance of amniotic fluid cytokines on the extracellular vesicle surface, within vesicles, and in the soluble fraction. These changes were most prominent in women with proven intra-amniotic infection. 2) Cytokine changes on the surface of extracellular vesicles were correlated with those determined in the soluble fraction; yet the magnitude of the increase was significantly different between these compartments. 3) The performance of prediction models of early preterm delivery based on measurements on the extracellular vesicle surface was equivalent to those based on the soluble fraction.

Conclusions

Differential packaging of amniotic fluid cytokines in extracellular vesicles during preterm labor with sterile intra-amniotic inflammation or proven intra-amniotic infection is reported herein for the first time. The current study provides insights into the biology of the intra-amniotic fluid ad may aid in the development of biomarkers for obstetrical disease.

Pro- and anti-inflammatory effects of sulforaphane on placental cytokine production

Placental inflammation increases the risk of adverse pregnancy outcomes and possibly neurodevelopmental disorders in the offspring. Previous research suggests it may be possible to modulate the placental immune response to bacteria to favor an anti-inflammatory phenotype with dietary factors. Sulforaphane (SFN) is a dietary supplement with known anti-inflammatory activities, however, its effects on placental cytokine production are unclear. Therefore, we evaluated the effects of SFN on biomarkers of inflammation and neurodevelopment under basal conditions and a setting of mild infection. Placental explant cultures were established and treated with up to 10 μM SFN in the presence and absence of 10⁷ CFU/ml heat-killed E. coli. Concentrations of IL-1β, TNF-α, IL-6, sgp130, HO-1 and BDNF in conditioned medium were quantified by immunoassay. SFN increased antioxidant HO-1 expression in the absence, but not the presence, of infection. SFN inhibited IL-1β and IL-10, but tended to promote, TNF-α production by bacteria-stimulated cultures. IL-6 and BDNF were inhibited by SFN irrespective of co-treatment with E.coli. A negative regulator of IL-6 signaling, sgp130, was increased by SFN under basal conditions, but not in E. coli-stimulated cultures. These results suggest that SFN has mixed effects on the placenta inhibiting both pro-inflammatory (IL-1β) and anti-inflammatory factors (IL-10) but promoting regulators of oxidative stress and inflammation (HO-1 and sgp130) in an infection-dependent manner.

Inflammation induced preterm labor and birth

Preterm birth which occurs before 37 weeks gestation is one of the most common obstetrical complication in humans. After many studies, it appears that "not one answer fits all" regarding the risk factors, causes and the treatments for this syndrome. However, it is becoming more evident that one of the major risk factors is inflammation and/or infection in the fetoplacental unit. In animal models (usually consisting of mice injected with lipopolysaccharide at 14 days of gestation), IL-22 and IL-6 have been identified as factors related to preterm birth. There are some clinical tests available to determine the risk for preterm labor and delivery, which can be identified before, during early, or at mid-gestation. However, treatment of preterm birth with antibiotics so far has not been "curable" and studies using anti-inflammatory treatments are not readily available. More studies regarding causes and treatments for preterm labor and delivery in humans are necessary to prevent neonatal deaths and/or developmental abnormalities associated with this common syndrome.

Alteration in Uterine Protease-Activated Receptor 2 Expression in Preterm Birth Induced Experimentally in Brp-39 Null Mutant Mice

Breast regression protein 39 (Brp-39) is a mouse homolog of human Chitinase 3-like 1, which belongs to the 18-glycosyl-hydrolase family and plays a role in inflammatory reaction and tissue remodeling. The aim of this study is to investigate the role of Brp-39 in a mouse model of preterm birth. Pregnant wild-type (WT) or Brp-39(-/-) mice were injected intraperitoneally with lipopolysaccharide (LPS) at embryonic day 15. Pregnancy outcomes were evaluated for 24 hours after LPS injection. Quantitative real-time polymerase chain reaction and immunoblotting were performed to analyze messenger RNA (mRNA) and protein expressions of cytokines and contraction-associated proteins in uterine and/or placental tissue after LPS injection. LPS injection led to preterm birth in both WT and Brp-39(-/-) mice, but the proportion of pubs delivered was reduced in Brp-39(-/-) mice, along with a longer interval from the LPS injection to delivery, compared to WT mice. Inflammatory cell infiltration and mRNA expression of cytokines and Ptgs2 in the uteri and the placentas were not significantly different between WT and Brp-39(-/-) mice. Par-2 mRNA expression in the WT uteri was increased before delivery after LPS injection and decreased after delivery, while there was no significant change in Par-2 expression in the Brp-39(-/-) uteri. Protein expressions of Par-2 and Ptgs2 were lower in the Brp-39(-/-) uteri than in the WT uteri before and after delivery. Attenuated preterm birth in Brp-39(-/-) mice indicates the significance of Brp-39 during murine preterm birth. Altered expression of Par-2 in Brp-39(-/-) uteri suggests its potential role in attenuated preterm birth of Brp-39(-/-) mice.

Periodontal infection with Porphyromonas gingivalis induces preterm birth and lower birth weight in rats

Preterm birth (PTB), accompanied by low birth weight (LBW) or not, is a syndrome with tremendous risk factors and long-term health consequences for children. In recent decades, overwhelming studies have shown that periodontitis contributes to prematurity and LBW. This study was conducted to determine the link between maternal periodontitis and the pathogenesis of PTB and/or LBW through a rat infection model induced by Porphyromonas gingivalis, an important periodontopathic bacterium. The murine model was established by surgically ligating the left mandibular first molars and inoculating with P. gingivalis, and then all female rats initiated mating 6 weeks post infection. The gestational day and birth weight were recorded, and blood, amniotic fluid, and placental specimens were collected. Rats with a PTB and LBW newborns were observed in the P. gingivalis-infected group. Additionally, P. gingivalis infection significantly increased the maternal serum levels of interferon-γ and interleukin-1β, whereas no significant difference in the cytokine response was observed in the amniotic fluid. Moreover, with the translocation of P. gingivalis to placentas, remarkable changes in gestational tissues were found, followed by significantly enhanced expression of Toll-like receptor 2 (TLR2) as well as Fas and Fas ligand (FasL). These results support the concept that severe cases of periodontitis caused by P. gingivalis infection may be indicative of rats being more susceptible to PTB/LBW, probably through the activation of the TLR2 and Fas/FasL pathways within the placental tissues. This study gave us new insight into how maternal periodontopathogens might be linked to placental damage and premature pathogenesis.

Intra-amniotic administration of lipopolysaccharide induces spontaneous preterm labor and birth in the absence of a body temperature change

OBJECTIVE

Intra-amniotic infection is associated with spontaneous preterm labor. In most cases, the infection is subclinical and bacteria are detected in the amniotic cavity rather than in the chorioamniotic membranes. The aims of this study were to establish a model of intra-amniotic lipopolysaccharide (LPS)-induced preterm labor/birth that resembles the subclinical syndrome and to compare this model to two established models of LPS-induced preterm labor/birth.

METHODS

Pregnant B6 mice received an intra-amniotic, intra-uterine, or intra-peritoneal injection of LPS (100 ng/amniotic sac, 15 μg/25 μL, and 15 μg/200 μL respectively) or PBS (control). Following injection, body temperature (every two hours for a 12-h period), gestational age, and the rate of preterm labor/birth were recorded.

RESULTS

An intra-amniotic injection of LPS resulted in preterm labor/birth [LPS 80 ± 24.79% (8/10) versus PBS 0% (0/8); p = 0.001] without causing maternal hypothermia. Intra-peritoneal [LPS 100% (8/8) versus PBS 0% (0/8); p < 0.001)] and intra-uterine [LPS 100% (8/8) versus PBS 28.57 ± 33.47% (2/7); p =0 .007] injections of LPS induced preterm labor/birth; yet, maternal hypothermia was observed.

CONCLUSION

Intra-amniotic injection of LPS induces preterm labor/birth in the absence of a body temperature change, which resembles the subclinical syndrome.

Neonatal protection and preterm birth reduction following maternal group B streptococcus vaccination in a mouse model

PURPOSE

Evaluate effects of maternal immunization in a mouse model of Group B Streptococcus (GBS) vaginal colonization using clinical isolates.

MATERIALS AND METHODS

Female pregnant mice were immunized with heat-killed GBS 21 days before pregnancy and were inoculated intravaginally with GBS cultures (5 × 10⁷ CFU twice a day for three days) from the 16th day of pregnancy. Gestation period and mice survival were monitored. Maternal anti-GBS IgG levels have been determined by ELISA analysis in vaccinated, unvaccinated mothers and newborns.

RESULTS

Maternal immunization before pregnancy provided protection to newborns for three of the four GBS strains used. Evaluation of the immunogenicity showed that this vaccination induced higher levels of IgG in vaccinated compared to unvaccinated dams and the presence of antibodies in the offspring at embryonic and postnatal age, and a Th1 response and high levels of IgG2a subclass antibody and IFN-γ were detected. A significant reduction of preterm births was observed in vaccinated mothers (p< 0.05).

CONCLUSIONS

Our finding suggest that vaccinated mothers could protect their progeny from GBS infection and preterm birth through passive immunization. The proposed mouse model may represent a noninvasive and effective tool to investigate pathogenetic mechanisms of GBS ascending infection and for vaccine protection studies.

N,N-Dimethylacetamide Significantly Attenuates LPS- and TNFα-Induced Proinflammatory Responses Via Inhibition of the Nuclear Factor Kappa B Pathway

Previously, we have shown that N,N-dimethylacetamide (DMA) prevents inflammation-induced preterm birth in a murine model, inhibits LPS-induced increases in placental pro-inflammatory cytokines and up-regulates the anti-inflammatory cytokine Interleukin-10 (IL-10). However, DMA's mechanism of action remains to be elucidated. In the current study we investigate how DMA produces its anti-inflammatory effect. Using in vitro and ex vivo models, we show that DMA suppresses secretion of pro-inflammatory cytokines in lipopolysaccharide (LPS)-induced RAW 264.7 cells, TNFα-challenged JEG-3 cells and LPS-stimulated human placental explants. DMA significantly attenuated the secretion of TNFα, IL-6, IL-10, and granulocyte macrophage colony stimulating factor (GM-CSF) from LPS-stimulated RAW 264.7 cells, IL-6 secretion from TNFα-stimulated JEG-3 cells and TNFα, IL-6, IL-10, GM-CSF and Interleukin-8 (IL-8) from LPS-stimulated human placental explants. We further investigated if DMA's effect on cytokine expression involves the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and mitogen-activated protein kinase (MAPK) pathways. DMA (10 mM) significantly inhibited nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (IκBα) degradation in LPS-stimulated RAW 264.7 cells, but there was no significant change in the expression of phosphorylated or native forms of downstream proteins in the MAPK pathway. In addition, DMA significantly attenuated luciferase activity in cells co-transfected with NF-κB-Luc reporter plasmid, but not with AP-1-Luc or CEBP-Luc reporters. Overall, our findings suggest that the anti-inflammatory activity of DMA is mediated by inhibition of the NF-κB pathway via decreased IκBα degradation.

Interferon-Gamma and Fas Are Involved in Porphyromonas gingivalis-Induced Apoptosis of Human Extravillous Trophoblast-Derived HTR8/SVneo Cells via Extracellular Signal-Regulated Kinase 1/2 Pathway

BACKGROUND

A number of studies recently revealed a link between periodontal disease and preterm birth (PTB). PTB can be induced by dental infection with Porphyromonas gingivalis (Pg), a periodontopathic bacterium. This study aims to investigate responses of human extravillous trophoblast-derived HTR8/SVneo cells to Pg infection.

METHODS

Cell apoptosis, cell viability, protein expression, and cytokine production in HTR8 cells were measured via: 1) flow cytometry, 2) CCK-8 assay, 3) western blot, and 4) enzyme-linked immunosorbent assay methods, respectively.

RESULTS

Pg decreased cell viability and increased cell apoptosis, active caspase-3 and Fas expression, and interferon-gamma (IFN-γ) secretion in HTR8 cells. Extracellular signal-regulated kinase (ERK) 1/2 inhibitor U0126 and FasL neutralizing antibody NOK1 that blocks FasL/Fas interaction both significantly suppressed Pg-induced apoptosis. U0126 also inhibited IFN-γ secretion and Fas expression close to control levels. Moreover, treatment with recombinant IFN-γ also significantly decreased number of viable HTR8 cells and increased Fas expression, suggesting IFN-γ may play an important role in Pg-induced apoptosis of HTR8 cells, at least partially through regulation of Fas expression.

CONCLUSIONS

To the best of the authors' knowledge, this is the first study to demonstrate Pg induces IFN-γ secretion, Fas expression, and apoptosis in human extravillous trophoblast-derived HTR8/SVneo cells in an ERK1/2-dependent manner, and IFN-γ (explored by recombinant IFN-γ) and Fas are involved in Pg-induced apoptosis. The finding that Pg infection abnormally regulates inflammation and apoptosis of human trophoblasts may give new insights into the possible link of PTB with maternal periodontal disease and periodontal pathogens.

Porphyromonas gingivalis induces IL-8 and IFN-gamma secretion and apoptosis in human extravillous trophoblast derived HTR8/SVneo cells via activation of ERK1/2 and p38 signaling pathways

INTRODUCTION

Preterm birth is a major cause for infant mortality and morbidity. A large number of studies have suggested a link between periodontal disease and preterm birth. The purpose of this study was to investigate the interaction between a periodontopathic bacterium Porphyromonas gingivalis and human extravillous trophoblast derived HTR8/SVneo cells.

METHODS

Production of cytokines in HTR8 cells was measured via ELISA. Annexin V/PI flow cytometry was performed to assess apoptosis. Protein expression was measured by western blot. Specific pharmacological inhibitors were used to inactivate relevant signaling pathways (p38 MAPK, SB203580; ERK1/2, U0126; JNK, SP600125; NF-κB, JSH-23) to determine their roles in inflammation and apoptosis.

RESULTS

HTR8 cells released significant amounts of IL-8 and IFN-γ during exposure to P. gingivalis. Meanwhile, the percentages of both early and late apoptotic cells increased significantly in response to P. gingivalis. The most significant effect on inflammation was found using SB203580 and U0126, followed by SP600125 and JSH-23. Moreover, U0126 and SB203580 both partially but significantly suppressed P. gingivalis-induced apoptosis, with a large effect by U0126. Additionally, both heat-killed P. gingivalis and P. gingivalis lipopolysaccharide significantly induced IL-8 production.

CONCLUSION

P. gingivalis induces inflammation and apoptosis in HTR8 cells, and we demonstrated for the first time that activation of ERK1/2 and p38 MAPK pathways participates in P. gingivalis-induced inflammation and apoptosis. The abnormal regulation of inflammation and apoptosis in human trophoblasts by P. gingivalis infection may give new insights into how maternal periodontal disease and periodontal pathogens might be linked to preterm birth.

alpha-actin down regulation and perforin loss in uterine natural killer cells from LPS-treated pregnant mice

One of the most abundant immunologic cell types in early decidua is the uterine natural killer (UNK) cell that despite the presence of cytoplasmic granules rich in perforin and granzymes does not degranulate in normal pregnancy. UNK cells are important producers of angiogenic factors that permit normal dilation of uterine arteries to provide increased blood flow for the growing feto-placental unit. Gram-negative bacteria lipopolysaccharide (LPS) administration can trigger an imbalance of pro-inflammatory and anti-inflammatory cytokines impairing the normal immune cells activity as well as uterine homeostasis. The present study aimed to evaluate by immunohistochemistry the reactivity of perforin and alpha-actin on UNK cell from LPS-treated pregnant mice. For the first time, we demonstrate that LPS injection in pregnant mice causes alpha-actin down regulation, concomitantly with perforin loss in UNK cells. This suggests that LPS alters UNK cell migration and activates cytotoxic granule release.

About one-half of early spontaneous preterm deliveries can be identified by a rapid matrix metalloproteinase-8 (MMP-8) bedside test at the time of mid-trimester genetic amniocentesis

OBJECTIVE

Mid-trimester amniocentesis continues to be used for the prenatal diagnosis of chromosomal anomalies and other genetic disorders. Analysis of amniotic fluid obtained at the time of mid-trimester genetic amniocentesis identifies those patients who are at risk for early spontaneous preterm delivery. This is based on a solid body of evidence that found subclinical intra-amniotic inflammation/infection to be causally linked to early spontaneous preterm birth. Although several biomarkers have been proposed to identify intra-amniotic inflammation, the accumulated data suggest that the determination of amniotic fluid matrix metalloproteinase-8 (MMP-8), or neutrophil collagenase, is a powerful predictor of spontaneous preterm delivery. MMP-8 is released by inflammatory cells in response to microbial products or "danger signals". A rapid point-of-care test has been developed to determine MMP-8 at the bedside within 20 min, and without the requirement of laboratory equipment. The objective of this study was to determine whether an elevation of MMP-8 in the amniotic fluid, measured by a rapid point-of-care test, can identify those patients at risk for spontaneous preterm delivery after a mid-trimester genetic amniocentesis.

STUDY DESIGN

A case-control study was designed to obtain amniotic fluid from asymptomatic singleton pregnant women who underwent mid-trimester genetic amniocentesis. An MMP-8 bedside test was performed to analyze the amniotic fluid of 64 patients with early spontaneous preterm delivery (<30 weeks) and 128 matched controls with normal pregnancy outcomes.

RESULTS

(1) The MMP-8 bedside test (Yoon's MMP-8 Check™) was positive in 42.2% (27/64) of patients with spontaneous preterm delivery but in none (0/128) of the control cases (p < 0.001); (2) the MMP-8 bedside test had a sensitivity of 42.2%, and a specificity of 100% in the prediction of spontaneous preterm delivery (<30 weeks) following a mid-trimester genetic amniocentesis; and (3) among the patients with spontaneous preterm delivery, those with a positive MMP-8 bedside test had a significantly higher rate of spontaneous delivery within 2 weeks and 4 weeks of an amniocentesis [40.7% (11/27) versus 5.4% (2/37); 63.0% (17/27) versus 24.3% (9/37)] and a shorter interval-to-delivery period than those with a negative test [interval-to-delivery: median (range), 16 d (0-95 d) versus 42 d (2-91 d); p < 0.05 for each].

CONCLUSION

We conclude that 42% of patients with an early spontaneous preterm delivery (< 30 weeks) could be identified by a rapid MMP-8 bedside test at the time of their mid-trimester genetic amniocentesis. The MMP-8 bedside test is a powerful predictor of early spontaneous preterm birth in asymptomatic pregnant women.

Gastric fluid versus amniotic fluid analysis for the identification of intra-amniotic infection due to Ureaplasma species

OBJECTIVE

Early neonatal sepsis is often due to intra-amniotic infection. The stomach of the neonate contains fluid swallowed before and during delivery. The presence of bacteria as well as neutrophils detected by culture or Gram stain of the gastric fluid during the first day of life is suggestive of exposure to bacteria or inflammation. We undertook this study to determine the relationship between gastric fluid analysis and amniotic fluid obtained by transabdominal amniocentesis in the detection of Ureaplasma species, the most frequent microorganisms responsible for intra-amniotic infection.

MATERIALS AND METHODS

The study population consisted of 100 singleton pregnant women who delivered preterm neonates (<35 weeks) within 7 days of amniocentesis. Gastric fluid of newborns was obtained by nasogastric intubation on the day of birth. Amniotic fluid and gastric fluid were cultured for genital Mycoplasmas, and polymerase chain reaction (PCR) for Ureaplasma species was performed. Intra-amniotic inflammation was defined as an elevated amniotic fluid matrix metalloproteinase-8 concentration (>23 ng/mL).

RESULTS

(1) Ureaplasma species were detected by culture or PCR in 18% (18/100) of amniotic fluid samples and in 5% (5/100) of gastric fluid samples; (2) among the amniotic fluid cases positive for Ureaplasma species, these microorganisms were identified in 27.8% (5/18) of gastric fluid samples; (3) none of the cases negative for Ureaplasma species in the amniotic fluid were found to be positive for these microorganisms in the gastric fluid; (4) patients with amniotic fluid positive for Ureaplasma species but with gastric fluid negative for these microorganisms had a significantly higher rate of intra-amniotic inflammation, acute histologic chorioamnionitis, and neonatal death than those with both amniotic fluid and gastric fluid negative for Ureaplasma species; and (5) no significant differences were observed in the rate of intra-amniotic inflammation, acute histologic chorioamnionitis, and neonatal death between patients with amniotic fluid positive for Ureaplasma species but with gastric fluid negative for these microorganisms and those with both amniotic fluid and gastric fluid positive for Ureaplasma species.

CONCLUSIONS

Gastric fluid analysis has 100% specificity in the identification of intra-amniotic infection with Ureaplasma species. However, the detection of Ureaplasma species by culture or PCR in the gastric fluid of neonates at birth did not identify these microorganisms in two-thirds of cases with microbial invasion of the amniotic cavity. Thus, amniotic fluid analysis is superior to that of gastric fluid in the identification of intra-amniotic infection.

Evidence of perturbations of the cytokine network in preterm labor

OBJECTIVE

Intraamniotic inflammation/infection is the only mechanism of disease with persuasive evidence of causality for spontaneous preterm labor/delivery. Previous studies about the behavior of cytokines in preterm labor have been largely based on the analysis of the behavior of each protein independently. Emerging evidence indicates that the study of biologic networks can provide insight into the pathobiology of disease and improve biomarker discovery. The goal of this study was to characterize the inflammatory-related protein network in the amniotic fluid of patients with preterm labor.

STUDY DESIGN

A retrospective cohort study was conducted that included women with singleton pregnancies who had spontaneous preterm labor and intact membranes (n = 135). These patients were classified according to the results of amniotic fluid culture, broad-range polymerase chain reaction coupled with electrospray ionization mass spectrometry, and amniotic fluid concentration of interleukin (IL)-6 into the following groups: (1) those without intraamniotic inflammation (n = 85), (2) those with microbial-associated intraamniotic inflammation (n = 15), and (3) those with intraamniotic inflammation without detectable bacteria (n = 35). Amniotic fluid concentrations of 33 inflammatory-related proteins were determined with the use of a multiplex bead array assay.

RESULTS

Patients with preterm labor and intact membranes who had microbial-associated intraamniotic inflammation had a higher amniotic fluid inflammatory-related protein concentration correlation than those without intraamniotic inflammation (113 perturbed correlations). IL-1β, IL-6, macrophage inflammatory protein (MIP)-1α, and IL-1α were the most connected nodes (highest degree) in this differential correlation network (degrees of 20, 16, 12, and 12, respectively). Patients with sterile intraamniotic inflammation had correlation patterns of inflammatory-related proteins, both increased and decreased, when compared to those without intraamniotic inflammation (50 perturbed correlations). IL-1α, MIP-1α, and IL-1β were the most connected nodes in this differential correlation network (degrees of 12, 10, and 7, respectively). There were more coordinated inflammatory-related protein concentrations in the amniotic fluid of women with microbial-associated intraamniotic inflammation than in those with sterile intraamniotic inflammation (60 perturbed correlations), with IL-4 and IL-33 having the largest number of perturbed correlations (degrees of 15 and 13, respectively).

CONCLUSIONS

We report for the first time an analysis of the inflammatory-related protein network in spontaneous preterm labor. Patients with preterm labor and microbial-associated intraamniotic inflammation had more coordinated amniotic fluid inflammatory-related proteins than either those with sterile intraamniotic inflammation or those without intraamniotic inflammation. The correlations were also stronger in patients with sterile intraamniotic inflammation than in those without intraamniotic inflammation. The findings herein could be of value in the development of biomarkers of preterm labor.

Advances in the Prevention of Infection-Related Preterm Birth

Infection-related preterm birth (PTB) is more common at early gestational ages and is associated with major neonatal mortality and morbidity. Abnormal genital tract microflora in early pregnancy predicts late miscarriage and early PTB. Accordingly, it is logical to consider antibiotics as an intervention. Unfortunately, the conclusions of systematic reviews and meta-analyses (SR&MAs) carried out in an attempt to explain the confusion over the heterogeneity of individual studies are flawed by the fact that undue reliance was placed on studies which: (a) had a suboptimal choice of antibiotic (mainly metronidazole) or used antibiotics not recommended for the treatment of bacterial vaginosis (BV) or BV-related organisms; (b) used antibiotics too late in pregnancy to influence outcome (23–27 weeks); and (c) included women whose risk of PTB was not due to abnormal genital tract colonization and hence unlikely to respond to antibiotics. These risks included: (a) previous PTB of indeterminate etiology; (b) low weight/body mass index; or (c) detection of fetal fibronectin, ureaplasmas, Group B streptococcus or Trichomonas vaginalis). While individual studies have found benefit of antibiotic intervention for the prevention of PTB, in meta-analyses these effects have been negated by large methodologically flawed studies with negative results. As a result, many clinicians think that any antibiotic given at any time in pregnancy to any woman at risk of PTB will cause more harm than good. Recently, a more focused SR&MA has demonstrated that antibiotics active against BV-related organisms, used in women whose risk of PTB is due to abnormal microflora, and used early in pregnancy before irreversible inflammatory damage has occurred, can reduce the rate of PTB. This review presents those data, the background and attempts to explain the confusion using new information from culture-independent molecular-based techniques. It also gives guidance on the structure of putative future antibiotic intervention studies.

Acute chorioamnionitis and funisitis: definition, pathologic features, and clinical significance

Acute inflammatory lesions of the placenta consist of diffuse infiltration of neutrophils at different sites in the organ. These lesions include acute chorioamnionitis, funisitis, and chorionic vasculitis and represent a host response (maternal or fetal) to a chemotactic gradient in the amniotic cavity. While acute chorioamnionitis is evidence of a maternal host response, funisitis and chorionic vasculitis represent fetal inflammatory responses. Intraamniotic infection generally has been considered to be the cause of acute chorioamnionitis and funisitis; however, recent evidence indicates that "sterile" intraamniotic inflammation, which occurs in the absence of demonstrable microorganisms induced by "danger signals," is frequently associated with these lesions. In the context of intraamniotic infection, chemokines (such as interleukin-8 and granulocyte chemotactic protein) establish a gradient that favors the migration of neutrophils from the maternal or fetal circulation into the chorioamniotic membranes or umbilical cord, respectively. Danger signals that are released during the course of cellular stress or cell death can also induce the release of neutrophil chemokines. The prevalence of chorioamnionitis is a function of gestational age at birth, and present in 3-5% of term placentas and in 94% of placentas delivered at 21-24 weeks of gestation. The frequency is higher in patients with spontaneous labor, preterm labor, clinical chorioamnionitis (preterm or term), or ruptured membranes. Funisitis and chorionic vasculitis are the hallmarks of the fetal inflammatory response syndrome, a condition characterized by an elevation in the fetal plasma concentration of interleukin-6, and associated with the impending onset of preterm labor, a higher rate of neonatal morbidity (after adjustment for gestational age), and multiorgan fetal involvement. This syndrome is the counterpart of the systemic inflammatory response syndrome in adults: a risk factor for short- and long-term complications (ie, sterile inflammation in fetuses, neonatal sepsis, bronchopulmonary dysplasia, periventricular leukomalacia, and cerebral palsy). This article reviews the definition, pathogenesis, grading and staging, and clinical significance of the most common lesions in placental disease. Illustrations of the lesions and diagrams of the mechanisms of disease are provided.

Alkaline phosphatase protects lipopolysaccharide-induced early pregnancy defects in mice

Excessive cytokine inflammatory response due to chronic or superphysiological level of microbial infection during pregnancy leads to pregnancy complications such as early pregnancy defects/loss and preterm birth. Bacterial toxin lipopolysaccharide (LPS), long recognized as a potent proinflammatory mediator, has been identified as a risk factor for pregnancy complications. Alkaline phosphatase (AP) isozymes have been shown to detoxify LPS by dephosphorylation. In this study, we examined the role of alkaline phosphatase (AP) in mitigating LPS-induced early pregnancy complications in mice. We found that 1) the uterus prior to implantation and implantation sites following embryo implantation produce LPS recognition and dephosphorylation molecules TLR4 and tissue non-specific AP (TNAP) isozyme, respectively; 2) uterine TNAP isozyme dephosphorylates LPS at its sites of production; 3) while LPS administration following embryo implantation elicits proinflammatory cytokine mRNA levels at the embryo implantation sites (EISs) and causes early pregnancy loss, dephosphorylated LPS neither triggers proinflammatory cytokine mRNA levels at the EISs nor induces pregnancy complications; 4) AP isozyme supplementation to accelerate LPS detoxification attenuates LPS-induced pregnancy complications following embryo implantation. These findings suggest that a LPS dephosphorylation strategy using AP isozyme may have a unique therapeutic potential to mitigate LPS- or Gram-negative bacteria-induced pregnancy complications in at-risk women.

Compensatory fetal membrane mechanisms between biglycan and decorin in inflammation

Preterm premature rupture of fetal membranes (PPROM) is associated with infection, and is one of the most common causes of preterm birth. Abnormal expression of biglycan and decorin, two extracellular matrix proteoglycans, leads to preterm birth and aberrant fetal membrane morphology and signaling in the mouse. In humans and mice, decorin dysregulation is associated with inflammation in PPROM. We therefore investigated the link between biglycan and decorin and inflammation in fetal membranes using mouse models of intraperitoneal Escherichia coli injections superimposed on genetic biglycan and decorin deficiencies. We assessed outcomes in vivo as well as in vitro using quantitative PCR, Western blotting, and enzyme-linked immunosorbent assays. Our results suggest that biglycan and decorin compensate for each other in the fetal membranes, but lose the ability to do so under inflammation, leading to decreased latency to preterm birth. Furthermore, our findings suggest that biglycan and decorin play discrete roles in fetal membrane signaling pathways during inflammation, leading to changes in the abundance of MMP8 and collagen α1VI, two components of the fetal membrane extracellular matrix that influence the pathophysiology of PPROM. In summary, these findings underline the importance of biglycan and decorin as targets for the manipulation of fetal membrane extracellular matrix stability in the context of inflammation.

Inhibition of sphingosine kinase prevents lipopolysaccharide-induced preterm birth and suppresses proinflammatory responses in a murine model

Premature delivery occurs in 12% of all births, and accounts for nearly half of long-term neurological morbidity, and 60% to 80% of perinatal mortality. Despite advances in obstetrics and neonatology, the rate of premature delivery has increased approximately 12% since 1990. The single most common cause of spontaneous preterm birth is infection. Several lines of evidence have demonstrated the role of endothelin-1 as both a constrictor of uterine myometrial smooth muscle and a proinflammatory mediator. Endothelin-1 activates the phospholipase C pathway, leading to activation of protein kinase C and, in turn, sphingosine kinase (SphK). The inhibition of SphK has been recently shown to control the proinflammatory response associated with sepsis. We show herein, for the first time, that SphK inhibition prevents inflammation-associated preterm birth in a murine model. Rescue of pups from premature abortion with an SphK inhibitor occurs by suppression of the proinflammatory cytokines tumor necrosis factor α, Il-1β, and Il-6 and attenuation of polymorphonuclear inflammatory cells into the placental labyrinth. Moreover, we postulate that inhibition of SphK leads to suppression of endothelin-converting enzyme-1 expression, indicating the presence of an endothelin-converting enzyme 1/endothelin 1-SphK positive feedback loop. This work introduces a novel approach for the control of infection-triggered preterm labor, a condition for which there is no effective treatment.

Group B Streptococcus β-hemolysin/cytolysin breaches maternal-fetal barriers to cause preterm birth and intrauterine fetal demise in vivo

BACKGROUND

Maternal vaginal colonization with Streptococcus agalactiae (Group B Streptococcus [GBS]) is a precursor to chorioamnionitis, fetal infection, and neonatal sepsis, but the understanding of specific factors in the pathogenesis of ascending infection remains limited.

METHODS

We used a new murine model to evaluate the contribution of the pore-forming GBS β-hemolysin/cytolysin (βH/C) to vaginal colonization, ascension, and fetal infection.

RESULTS

Competition assays demonstrated a marked advantage to βH/C-expressing GBS during colonization. Intrauterine fetal demise and/or preterm birth were observed in 54% of pregnant mice colonized with wild-type (WT) GBS and 0% of those colonized with the toxin-deficient cylE knockout strain, despite efficient colonization and ascension by both strains. Robust placental inflammation, disruption of maternal-fetal barriers, and fetal infection were more frequent in animals colonized with WT bacteria. Histopathologic examination revealed bacterial tropism for fetal lung and liver.

CONCLUSIONS

Preterm birth and fetal demise are likely the direct result of toxin-induced damage and inflammation rather than differences in efficiency of ascension into the upper genital tract. These data demonstrate a distinct contribution of βH/C to GBS chorioamnionitis and subsequent fetal infection in vivo and showcase a model for this most proximal step in GBS pathogenesis.

MyD88 signaling is directly involved in the development of murine placental malaria

Malaria is a widespread infectious disease caused by the parasite Plasmodium. During pregnancy, malaria infection leads to a range of complications that can affect both the mother and fetus, including stillbirth, infant mortality, and low birth weight. In this study, we utilized a mouse model of placental malaria (PM) infection to determine the importance of the protein MyD88 in the host immune response to Plasmodium during pregnancy. Initially, we demonstrated that Plasmodium berghei NK65GFP adhered to placental tissue via chondroitin sulfate A and induced PM in mice with a C57BL/6 genetic background. To evaluate the involvement of MyD88 in the pathology of PM, we performed a histopathological analysis of placentas obtained from MyD88(-/-) and wild-type (WT) mice following infection on the 19th gestational day. Our data demonstrated that the detrimental placental alterations observed in the infected mice were correlated with the expression of MyD88. Moreover, in the absence of this protein, production of interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-α) was significantly reduced in the infected mice. More importantly, in contrast to fetuses from infected WT mice, which exhibited a reduction in body weight, the fetuses from infected MyD88(-/-) mice did not display significant weight loss compared to their noninfected littermates. In addition, we observed a decrement of maternal care associated with malaria infection, which was attenuated in the MyD88-deficient mice. Collectively, the results of this study illustrate the pivotal importance of the MyD88 signaling pathway in the pathogenesis of placental malaria, thus presenting new possibilities for targeting MyD88 in therapeutic interventions.

N,N-dimethylacetamide regulates the proinflammatory response associated with endotoxin and prevents preterm birth

The proinflammatory response leads to various types of pathologic pathways, including the development of preterm birth. Preterm birth occurs in 12% of deliveries in the United States and causes more than 70% of perinatal morbidity and mortality. The most common cause of spontaneous preterm birth is intrauterine infection in the mother. There is accumulating evidence indicating that the release of proinflammatory cytokines plays a critical role in the pathogenesis of inflammation-associated premature delivery. We found that the common organic solvent, N,N-dimethylacetamide (DMA), prevents endotoxin-induced preterm birth in timed pregnant C57BL/6 embryonic day (E)15.5 mice and rescues their pups from spontaneous abortion at doses many-fold lower than those currently used clinically and in a dose-dependent fashion. We also provide histologic evidence that DMA suppresses the endotoxin-triggered proinflammatory response by significantly attenuating inflammatory cell infiltration of placental tissue. Furthermore, immunoblotting analysis of placental tissue harvested from our murine models revealed DMA-mediated regulation of expression of the proinflammatory cytokines IL-1β, tumor necrosis factor α, and IL-6, and increased expression of the regulatory inflammatory cytokine IL-10. By using in vitro studies, we provide evidence that DMA suppresses macrophage function and that this small molecule prevents nuclear translocation of nuclear factor-kB. These results suggest that DMA represents a newly discovered, nontoxic therapy for a broad range of inflammatory disorders.

The consequences of chorioamnionitis: preterm birth and effects on development

Preterm birth is a major cause of perinatal mortality and long-term morbidity. Chorioamnionitis is a common cause of preterm birth. Clinical chorioamnionitis, characterised by maternal fever, leukocytosis, tachycardia, uterine tenderness, and preterm rupture of membranes, is less common than subclinical/histologic chorioamnionitis, which is asymptomatic and defined by inflammation of the chorion, amnion, and placenta. Chorioamnionitis is often associated with a fetal inflammatory response. The fetal inflammatory response syndrome (FIRS) is defined by increased systemic inflammatory cytokine concentrations, funisitis, and fetal vasculitis. Clinical and epidemiological studies have demonstrated that FIRS leads to poor cardiorespiratory, neurological, and renal outcomes. These observations are further supported by experimental studies that have improved our understanding of the mechanisms responsible for these outcomes. This paper outlines clinical and experimental studies that have improved our current understanding of the mechanisms responsible for chorioamnionitis-induced preterm birth and explores the cellular and physiological mechanisms underlying poor cardiorespiratory, neural, retinal, and renal outcomes observed in preterm infants exposed to chorioamnionitis.

Mice deficient in surfactant protein A (SP-A) and SP-D or in TLR2 manifest delayed parturition and decreased expression of inflammatory and contractile genes

Previously we obtained compelling evidence that the fetus provides a critical signal for the initiation of term labor through developmental induction of surfactant protein (SP)-A expression by the fetal lung and secretion into amniotic fluid (AF). We proposed that interactions of AF macrophage (Mϕ) Toll-like receptors (TLRs) with SP-A, at term, or bacterial components, at preterm, result in their activation and migration to the pregnant uterus. Herein the timing of labor in wild-type (WT) C57BL/6 mice was compared with mice homozygous null for TLR2, SP-A, SP-D, or doubly deficient in SP-A and SP-D. Interestingly, TLR2(-/-) females manifested a significant (P < 0.001) delay in timing of labor compared with WT as well as reduced expression of the myometrial contraction-associated protein (CAP) gene, connexin-43, and Mϕ marker, F4/80, at 18.5 d postcoitum (dpc). Whereas in first pregnancies, SP-A(-/-), SP-D(-/-), and SP-A/D(-/-) females delivered at term (∼19.5 dpc), in second pregnancies, parturition was delayed by approximately 12 h in SP-A(-/-) (P = 0.07) and in SP-A/D(-/-) (P <0.001) females. Myometrium of SP-A/D(-/-) females expressed significantly lower levels of IL-1β, IL-6, and CAP genes, connexin-43, and oxytocin receptor at 18.5 dpc compared with WT. F4/80(+) AF Mϕs from TLR2(-/-) and SP-A/D(-/-) mice expressed significantly lower levels of both proinflammatory and antiinflammatory activation markers (e.g. IL-1β, IL-6, ARG1, YM1) compared with gestation-matched WT AF Mϕs. These novel findings suggest that the pulmonary collectins acting via TLR2 serve a modulatory role in the timing of labor; their relative impact may be dependent on parity.

Protein Microarrays and Midtrimester Amniotic Fluids: A Novel Approach for the Diagnosis of Early Intrauterine Inflammation Related to Preterm Delivery

Novel technologies that allow simultaneous assessment of multiple biomarkers provide new and promising diagnostic/prognostic approaches. By protein microarrays, here we analyzed amniotic fluids (AF) from 50 women with preterm delivery (PTD) and 50 control women, who delivered at term. In detail, cytokines, chemokines, matrix metalloproteinases and antigen-specific antibodies were assessed. The AF analysis showed significant differences between women with preterm and term delivery in the levels of IL-1α, IL-1β, IL-4, IL-6, IL-8, MCP-1, IFN-γ and anti-HSV2 IgG. No significant differences were observed in the levels of TNF-α, MMP-2, MMP-9 and specific IgG for seven vertically transmitted pathogens. In conclusion, we demonstrated the feasibility of protein microarrays in the diagnosis of early intrauterine inflammation. The significant association between the increased levels of certain cytokines and preterm delivery argues on their relevance as early pathogenetic markers for identification of risk patients.

TLR9 provokes inflammation in response to fetal DNA: mechanism for fetal loss in preterm birth and preeclampsia

Preterm birth, the major cause of neonatal mortality in developed countries, is associated with intrauterine infections and inflammation, although the exact mechanisms underlying this event are unclear. In this study, we show that circulating fetal DNA, which is elevated in pregnancies complicated by preterm labor or preeclampsia, triggers an inflammatory reaction that results in spontaneous preterm birth. Fetal DNA activates NF-κB, shown by IκBα degradation in human PBMCs resulting in production of proinflammatory IL-6. We show that fetal resorption and preterm birth are rapidly induced in mice after i.p. injection of CpG or fetal DNA (300 μg/dam) on gestational day 10-14. In contrast, TLR9(-/-) mice were protected from these effects. Furthermore, this effect was blocked by oral administration of the TLR9 inhibitor chloroquine. Our data therefore provide a novel mechanism for preterm birth and preeclampsia, highlighting TLR9 as a potential therapeutic target for these common disorders of pregnancy.

Gonadal and nongonadal FSHR and LHR dysfunction during lipopolysaccharide induced failure of blastocyst implantation in mouse

PURPOSE

The purpose of the present study was to investigate the impact of lipopolysaccharide (LPS) on follicle-stimulating hormone (FSH), luteinizing hormone (LH) and their receptors during preimplantation days of pregnancy.

METHOD

The PBS or lipopolysaccharide (LPS) was injected intraperitoneally in the pregnant females on day 0.5 of pregnancy and serum, embryos, ovaries and uterine horns were collected on days 1.5, 2.5, 3.5, 4.0, 4.125, 4.33 and 4.42 of pregnancy.

RESULT(S)

In the LPS-treated pregnant females, the secretion of FSH and LH is disturbed with respect to normal pregnancy. Furthermore, the expression of FSHR mRNA in embryos and ovaries, LHR mRNA in embryos and uterus get modulated in response to LPS during preimplantation days of pregnancy.

CONCLUSION(S)

The disturbance in the serum level of FSH and LH in response to LPS leads implantation failure in mouse which suggests that these gonadotropins plays an integral role in the process of the successful implantation. This study also suggests a possible nongonadal role of FSHR and LHR in LPS-induced implantation failure in the mouse.

The role of inflammation and infection in preterm birth

Much emphasis in recent decades has been devoted to inflammation and infection as a premier causal mechanism of preterm birth. This article explores the epidemiologic, clinical, and animal data that exist to support this conceptual paradigm as well as proposed mechanisms through which to potentially mitigate the adversity of prematurity. Truly successful interventions are not likely to occur until the pathogenesis of preterm birth and the role of inflammation in causing not only parturition but also fetal and neonatal injury is fully elucidated.

Treatment of abnormal vaginal flora in early pregnancy with clindamycin for the prevention of spontaneous preterm birth: a systematic review and metaanalysis

The purpose of this study was to determine whether the administration of clindamycin to women with abnormal vaginal flora at <22 weeks of gestation reduces the risk of preterm birth and late miscarriage. We conducted a systematic review and metaanalysis of randomized controlled trials of the early administration of clindamycin to women with abnormal vaginal flora at <22 weeks of gestation. Five trials that comprised 2346 women were included. Clindamycin that was administered at <22 weeks of gestation was associated with a significantly reduced risk of preterm birth at <37 weeks of gestation and late miscarriage. There were no overall differences in the risk of preterm birth at <33 weeks of gestation, low birthweight, very low birthweight, admission to neonatal intensive care unit, stillbirth, peripartum infection, and adverse effects. Clindamycin in early pregnancy in women with abnormal vaginal flora reduces the risk of spontaneous preterm birth at <37 weeks of gestation and late miscarriage. There is evidence to justify further randomized controlled trials of clindamycin for the prevention of preterm birth. However, a deeper understanding of the vaginal microbiome, mucosal immunity, and the biology of BV will be needed to inform the design of such trials.

Surfactant protein A modulates the lipopolysaccharide-induced inflammatory response related to preterm birth

Surfactant protein A (SP-A) functions in homeostasis of lung surfactant and in innate immunity. SP-A is secreted by the fetal lung into amniotic fluid. Additionally it has been detected in gestational tissues. We propose that SP-A influences intrauterine inflammation that is commonly associated with preterm birth, the main underlying cause of neonatal mortality and morbidity. We used our previously established mouse model of LPS-induced preterm birth of live-born pups to investigate the role of SP-A in preterm birth. Mice overexpressing rat SP-A (rSP-A) under the control of human SP-C promoter were used. Cytokine concentrations in maternal and fetal serum and in amniotic fluid and mRNA levels of several inflammatory mediators in lungs and in intrauterine tissues were quantified using Cytometric Bead Array and RNase Protection Assay, respectively. Higher levels of SP-A mRNA were observed in fetal lungs and intrauterine tissues of rSP-A mice compared with wild-type. Using Western blot we detected excess of SP-A protein in fetal lung and in amniotic fluid of rSP-A animals. Despite some differences in the basal levels of TNF-α and IL-10 between rSP-A and wild-type animals, there were no differences in the duration of pregnancy. However, the levels of TNF-α, IL-10 and some other inflammatory mediators in intrauterine tissues and in amniotic fluid differed significantly between the mouse lines after maternal LPS given at 17dpc. We conclude that SP-A modulates the levels of intrauterine inflammatory mediators involved in preterm birth and may contribute to inflammatory processes related to spontaneous preterm labor.

Functional screening of TLRs in human amniotic epithelial cells

Intrauterine infection is a major cause of spontaneous preterm birth. Amniotic epithelial cells represent the first line of defense against intra-amniotic bacteria. We hypothesize that this epithelial cell barrier is able to recognize and respond to pathogens through the function of TLRs, which are crucial regulators of the innate immune system. In this study, we describe the expression of transcripts for TLR1-TLR10 in human amniotic epithelial cells. We show that amniotic epithelial cells express functional TLR5, TLR6/2, and TLR4. Activation by TLR5 and TLR6/2 agonists produces IL-6 and IL-8, concomitantly with the activation of NF-κB signaling pathway, matrix metalloproteinase-9 induction, and PTGS2 expression. In contrast, TLR4 activation reduced amniotic epithelial cell viability and induced cell apoptosis evidenced by an elevated Bax/Bcl-2 ratio and cleavage of caspase-3. These data suggest specific TLR-mediated functions in human amniotic epithelial cells for initiating different immune responses, which ultimately may lead to preterm birth.

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. Quantitative reverse transcriptase polymerase chain reaction (RT-PCR) confirmed increased PAI-1 messenger RNA (mRNA) in the uteri, lung, kidney, and liver tissues at 2 to 6 hours after LPS injection. In contrast, TF expression significantly decreased by 12 hours in uterine tissue; whereas, its expression was unchanged in the other maternal tissues. The uterine mRNA for Par1, Par2, Fgl2, and TM remained stable. In summary, these studies have confirmed expression of coagulation pathway genes within the pregnant uterus; some of which are modulated during LPS-induced PTD.

Effect of polymyxin B on gram-negative bacterial infection during pregnancy

OBJECTIVE

Polymyxin B (PB) is a naturally occurring cationic cyclic decapeptide which is highly bactericidal to Gram-negative bacteria. The objective of this study was to investigate the effect of PB on the viability of developing embryos during pregnancy and to validate its protective effect on the embryotoxic effect of Gram-negative bacterial lipopolysaccharide (LPS).

MATERIAL AND METHODS

Animals were injected intraperitoneally (i.p.) with PB (5-100 μg/animal), (Minimum effective dose) MD of LPS and MD of LPS+PB (5-100 μg/animal) on day 0.5 of pregnancy. The percentage of normal gestational sacs and histopathologic analysis were assessed.

RESULTS

PB treatment of pregnant females disturbs the pregnancy in a dose dependent manner and increases the substantial risk of congenital abnormalities in the growing fetuses of the mother. However, PB does not show any adverse effect on implantation of embryos. The embryotoxic effect of LPS can be prevented completely by 25 μg PB/animal; however other lower and higher doses of PB were not able to protect against the effect of LPS on pregnancy.

CONCLUSIONS

Our results demonstrate that PB has the ability to protect the LPS-induced pregnancy loss but may not be recommended as a safe drug for the treatment of a mother suffering from Gram-negative bacterial infection during pregnancy.

Upregulated amniotic fluid cytokines and chemokines in emergency cerclage with protruding membranes

PROBLEM  To identify the prognostic factors for pregnancy outcome in women who received emergency cerclage for dilated cervix with protruding membranes. METHOD OF STUDY  A prospective cohort study was performed, and a total of 14 women who received emergency cerclage were included. Clinical features and laboratory findings including amniotic fluid cytokines and chemokines were compared between women who had successful pregnancy (survival group, n = 6) and those who had perinatal death (non-survival group, n = 8). Five healthy pregnant women served for normal controls for amniotic fluid study. RESULTS  The overall neonatal survival was 42.9% in women with emergency cerclage. Serum C-reactive protein levels on postoperative day 3 and 7 were significantly higher in non-survival group when compared with those in survival group (P = 0.002, P = 0.01). Amniotic fluid levels of interleukin (IL)-1α, IL-1β, IL-6, IL-8, IL-10, tumor necrosis factor-α, and monocyte chemoattractant protein-1 levels of the patients were significantly higher than those of normal controls. Amniotic fluid levels of IL-1α, IL-1β, and IL-8 were significantly increased in the non-survival group when compared with those of the survival group. CONCLUSION  Systemic and local inflammatory markers including proinflammatory cytokines and chemokines may predict pregnancy outcome in women with emergency cerclage for dilated cervix with protruding membranes.

Placental inflammation and fetal hemodynamics in a rat model of chorioamnionitis

The relative contributions of inflammation and ischemia to the pathogenesis of periventricular leukomalacia (PVL) have not been elucidated. We hypothesized that fetal cardiovascular function and cerebral blood flow velocity (BFV) would be decreased in a rat model of chorioamnionitis. We also tested whether placental inflammation was related to proximity to the cervix in our model of chorioamnionitis [intracervical lipopolysaccharide (LPS) or vehicle (PBS) injection]. On embryonic d 15, Sprague-Dawley rats underwent baseline maternal and fetal echocardiography, followed by LPS or PBS injection, then serial echocardiographic evaluations until embryonic day (ED) 21. One hour after birth, pups had middle cerebral artery (MCA) BFV measured. Placentas of LPS-exposed pups exhibited uniform, higher inflammation grades (p < 0.001). All fetal BFVs increased with advancing GA (p < 0.001) whereas resistance index (RI) decreased (p < 0.001). There was no difference in fetal BFV between the groups other than a reduced gestation-related increase in descending aorta BFV in LPS-exposed rats (p < 0.05). Newborn pups exposed to LPS had lower heart rate (p = 0.006) and MCA BFV (p = 0.024) and higher RI (p = 0.003) and pulsatility index (PI; p = 0.004). In conclusion, intracervical LPS injection produces an inflammation independent of placental position, a blunted increase in gestation-related aortic BFV, and a decrease in MCA BFV in newborn pups.

Human trophoblast responses to Porphyromonas gingivalis infection

Porphyromonas gingivalis is a periodontal pathogen that is also associated with preterm low-birthweight delivery. We investigated the transcriptional responses of human extravillous trophoblasts (HTR-8) to infection with P. gingivalis. Over 2000 genes were differentially regulated in HTR-8 cells by P. gingivalis. In ontology analyses of regulated genes, overpopulated biological pathways included mitogen-activated protein (MAP) kinase signaling and cytokine production. Immunoblots confirmed overexpression of the MAP kinase pathway components MEK3, p38 and Max. Furthermore, P. gingivalis infection induced phosphorylation and activation of MEK3 and p38. Increased production of interleukin (IL)-1beta and IL-8 by HTR-8 cells was demonstrated phenotypically by enzyme-linked immunosorbent assay of HTR-8 cell lysates and culture supernatants. Hence, infection of trophoblasts by P. gingivalis can impact signal transduction pathways and modulate cytokine expression, outcomes that could disrupt the maintenance of pregnancy.

Blockade of endothelin-1 with a novel series of 1,3,6-trisubstituted-2-carboxy-quinol-4-ones controls infection-associated preterm birth

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.

TLR-mediated preterm birth in response to pathogenic agents

The incidence of preterm birth in developed countries has risen in the past decades. Underlying causes for this enigmatic pregnancy complication are numerous, yet infectious agents that induce dysregulation of immunity at the maternal-fetal interface pose one of the most probable causes of preterm birth. This paper highlights two factors regarding maternal infections that trigger unscheduled inflammatory sequences that are deleterious to the maternal-fetal balance necessary to maintain pregnancy. Firstly, we discuss the role of Toll-like receptors (TLRs) as sentinels of uterine immunity in the context of response to pathogens. We highlight the idea that particular TLR activations lead to differential immune cascades that induce preterm birth. Secondly, two alternative routes of pathogenic entry may prove to be critical for inducing preterm birth via a cytokine storm or a secondary and currently unknown cell-mediated mechanism of uterine inflammation. This paper summarizes pathways that underlie activation of adverse and diverse immune responses to foreign agents that may result in preterm birth.

The matrix metalloproteases and endothelin-1 in infection-associated preterm birth

Preterm birth (PTB) is clinically defined as any delivery which occurs before the completion of 37 weeks of gestation, and is currently the most important problem in obstetrics. In the United States, PTB accounts for 12-13% of all live births, and, with the exception of fetuses suffering from anomalies, is the primary cause of perinatal mortality. While the risk factors for PTB are numerous, the single most common cause is intrauterine infection. As there is currently no FDA-approved therapy for infection-associated PTB, understanding the pathogenesis of preterm labor (PTL) and delivery should be given high priority. The matrix metalloproteinases (MMPs) are a family of enzymes that have been implicated in normal parturition as well as infection-triggered rupture of membranes and preterm birth. Several lines of evidence also suggest a role for endothelin-1 (ET-1) in infection-associated preterm delivery. This paper focuses on the evidence that the MMPs and ET-1 act in the same molecular pathway in preterm birth.

Innate inflammatory responses of human decidual cells to periodontopathic bacteria

OBJECTIVE

The purpose of this study was to test the hypothesis that periodontopathic bacteria exert potent proinflammatory effects in human decidua.

STUDY DESIGN

The immunostimulatory effects of Gram-positive and negative periodontopathic bacteria and their lipopolysaccharides were tested in human decidual cell cultures in comparison with Escherichia coli. Cytokine production was measured by enzyme-linked immunosorbent assay; inflammatory gene expression was measured by oligonucleotide arrays and quantitative real time-polymerase chain reaction.

RESULTS

All bacteria that were tested elicited an inflammatory response, although concentration-dependence and efficacy varied considerably with organism and culture. Lipopolysaccharides were more potent stimuli than intact bacterial cells, although bacteria exerted greater effects at high concentrations. Of 112 genes on the arrays, 18 genes were stimulated significantly by one or more lipopolysaccharide preparation.

CONCLUSION

The ability of periodontopathic bacteria to stimulate a decidual inflammatory response is highly variable and partly dependent on the presence and structure of constituent lipopolysaccharides. This adds to our understanding of the causal association between periodontal disease and preterm birth.

Pentraxin 3 in amniotic fluid: a novel association with intra-amniotic infection and inflammation

OBJECTIVE

Pentraxin 3 (PTX3) is a soluble pattern recognition receptor (PRR) that has an important role in immunoregulation and vascular integrity. The aim of this study was to determine if PTX3 is present in amniotic fluid (AF) and whether its concentration changes with gestational age (GA), in the presence of preterm or term labor, and in cases of intra-amniotic infection/inflammation (IAI) associated with spontaneous preterm labor (PTL) or preterm prelabor rupture of membranes (PROM).

STUDY DESIGN

This cross-sectional study included the following groups: 1) mid-trimester (n=45); 2) uncomplicated pregnancies at term with (n=48) and without (n=40) spontaneous labor; 3) women with PTL and intact membranes who: a) delivered at term (n=44); b) delivered preterm without IAI (n=40); or c) delivered preterm with IAI (n=62); 4) women with preterm PROM with (n=63) and without (n=36) IAI. PTX3 concentration in AF was determined by ELISA. Non-parametric statistics were used for analyses.

RESULTS

1) Among women with PTL and intact membranes, the median AF PTX3 concentration was significantly higher in women with IAI than in those without IAI (7.95 ng/mL vs. 0.38 ng/mL; P<0.001) and than in those who delivered at term (0.55 ng/mL; P<0.001); 2) women with preterm PROM and IAI had a higher median AF PTX3 concentration than those without IAI (9.12 ng/mL vs. 0.76 ng/mL; P<0.001); 3) the median AF PTX3 concentration did not change with GA (mid-trimester: 0.79 ng/mL vs. term not in labor: 0.58 ng/mL; P=0.09); and 4) labor at term was not associated with a significant change of AF PTX 3 concentration (in labor: 0.54 ng/mL vs. not in labor: 0.58 ng/mL, P=0.9).

CONCLUSIONS

PTX3 is a physiologic constituent of the AF, and its median concentration is elevated in the presence of IAI, suggesting that PTX3 may play a role in the innate immune response against IAI.

Adiponectin in amniotic fluid in normal pregnancy, spontaneous labor at term, and preterm labor: a novel association with intra-amniotic infection/inflammation

OBJECTIVE

Adiponectin, an anti-inflammatory and anti-diabetogenic adipokine, has an important regulatory effect on both the innate and adaptive limbs of the immune response. The objective of this study was to determine whether adiponectin is present in amniotic fluid (AF) and if its concentration changes with gestational age, in the presence of labor, and in the presence of intra-amniotic infection (IAI) in patients with spontaneous preterm labor (PTL) and intact membranes.

STUDY DESIGN

This cross-sectional study included 468 patients in the following groups: (1) women in the mid-trimester of pregnancy (14-18 weeks) who underwent amniocentesis for genetic indications and delivered a normal neonate at term (n = 52); (2) normal pregnant women at term with (n = 49) and without (n = 41) spontaneous labor; (3) patients with an episode of PTL and intact membranes who were classified into: (a) PTL who delivered at term (n = 149); (b) PTL who delivered preterm (<37 weeks gestation) without IAI (n = 108); and (c) PTL with IAI (n = 69). Adiponectin concentration in AF was determined by ELISA.

RESULTS

(1) The median AF adiponectin concentration at term was significantly higher than in the mid-trimester (35.6 ng/ml, interquartile range [IQR] 26.4-52.7 vs. 29.9 ng/ml, IQR 19.9-35.2; p = 0.01); (2) among women with PTL and intact membranes, the median AF adiponectin concentration was significantly higher in patients with IAI than in those without IAI who delivered either at term (54.3 ng/ml, 39.0-91.8 vs. 50.1 ng/ml, 33.2-72.8; p = 0.02) or preterm (47.6 ng/ml, 32.6-74.6; p = 0.01); and (3) among women at term, there was no significant difference in the median AF adiponectin concentration between those with and without labor (33.7 ng/ml, IQR 21.7-53.9 vs. 35.6 ng/ml, IQR 26.4-52.7; respectively p = 0.5).

CONCLUSIONS

(1) Adiponectin is a physiologic constituent of AF; and (2) adiponectin concentrations in AF are increased significantly with advancing gestation and in the presence of IAI. Collectively, these findings suggest that adiponectin plays a dynamic role in normal gestation and in the presence of IAI.