Indomethacin blocks interleukin 1beta-induced myometrial contractions in pregnant rhesus monkeys

Gestation-dependent increase in cervicovaginal pro-inflammatory cytokines and cervical extracellular matrix proteins is associated with spontaneous preterm delivery within 2 weeks of index assessment in South African women

Introduction

Inflammation-induced remodelling of gestational tissues that underpins spontaneous preterm birth (sPTB, delivery < 37 weeks' gestation) may vary by race and context. To explore relationships between markers of these pathological processes, we (a) characterised the cervicovaginal fluid (CVF) cytokine profiles of pregnant South African women at risk of PTB; (b) determined CVF matrix-metalloproteinase-9 (MMP-9) and its regulator tissue inhibitor of metalloproteinase-1 (TIMP-1); and (c) explored the predictive potential of these markers for sPTB.

Method of study

The concentrations of 10 inflammatory cytokines and MMP-9 and TIMP-1 were determined by ELISA in CVF samples from 47 non-labouring women at high risk of PTB. We studied CVF sampled at three gestational time points (GTPs): GTP1 (20-22 weeks, n = 37), GTP2 (26-28 weeks, n = 40), and GTP3 (34-36 weeks, n = 29) and analysed for changes in protein concentrations and predictive capacities (area under the ROC curve (AUC) and 95% confidence interval (CI)) for sPTB.

Results

There were 11 (GTP1), 13 (GTP2), and 6 (GTP3) women who delivered preterm within 85.3 ± 25.9, 51.3 ± 15.3, and 11.8 ± 7.5 (mean ± SD) days after assessment, respectively. At GTP1, IL-8 was higher (4-fold, p = 0.02), whereas GM-CSF was lower (~1.4-fold, p = 0.03) in the preterm compared with term women with an average AUC = 0.73. At GTP2, IL-1β (18-fold, p < 0.0001), IL-8 (4-fold, p = 0.03), MMP-9 (17-fold, p = 0.0007), MMP-9/TIMP-1 ratio (9-fold, p = 0.004), and MMP-9/GM-CSF ratio (87-fold, p = 0.005) were higher in preterm compared with term women with an average AUC = 0.80. By contrast, IL-10 was associated with term delivery with an AUC (95% CI) = 0.75 (0.55-0.90). At GTP3, IL-1β (58-fold, p = 0.0003), IL-8 (12-fold, p = 0.002), MMP-9 (296-fold, p = 0.03), and TIMP-1 (35-fold, p = 0.01) were higher in preterm compared with term women with an average AUC = 0.85. Elevated IL-1β was associated with delivery within 14 days of assessment with AUC = 0.85 (0.67-0.96). Overall, elevated MMP-9 at GTP3 had the highest (13.3) positive likelihood ratio for distinguishing women at risk of sPTB. Lastly, a positive correlation between MMP-9 and TIMP-1 at all GTPs (ρ ≥ 0.61, p < 0.01) for women delivering at term was only observed at GTP1 for those who delivered preterm (ρ = 0.70, p < 0.03).

Conclusions

In this cohort, sPTB is associated with gestation-dependent increase in pro-inflammatory cytokines, decreased IL-10 and GM-CSF, and dysregulated MMP-9-TIMP-1 interaction. Levels of cytokine (especially IL-1β) and ECM remodelling proteins rise significantly in the final 2 weeks before the onset of labour when sPTB is imminent. The signalling mechanisms for these ECM remodelling observations remain to be elucidated.

The eNAMPT/TLR4 inflammatory cascade drives the severity of intra-amniotic inflammation in pregnancy and predicts infant outcomes

Introduction: Intra-amniotic inflammation (IAI) or chorioamnionitis is a common complication of pregnancy producing significant maternal morbidity/mortality, premature birth and neonatal risk of chronic lung diseases such as bronchopulmonary dysplasia (BPD). We examined eNAMPT (extracellular nicotinamide phosphoribosyltransferase), a critical inflammatory DAMP and TLR4 ligand, as a potential therapeutic target to reduce IAI severity and improve adverse fetal/neonatal outcomes. Methods: Blood/tissue samples were examined in: 1) women with histologically-proven chorioamnionitis, 2) very low birth weight (VLBW) neonates, and 3) a preclinical murine pregnancy model of IAI. Groups of pregnant IAI-exposed mice and pups were treated with an eNAMPT-neutralizing mAb. Results: Human placentas from women with histologically-proven chorioamnionitis exhibited dramatic NAMPT expression compared to placentas without chorioamnionitis. Increased NAMPT expression in whole blood from VLBW neonates (day 5) significantly predicted BPD development. Compared to untreated LPS-challenged murine dams (gestational day 15), pups born to eNAMPT mAb-treated dams (gestational days 15/16) exhibited a > 3-fold improved survival, reduced neonate lung eNAMPT/cytokine levels, and reduced development and severity of BPD and pulmonary hypertension (PH) following postnatal exposure to 100% hyperoxia days 1-14. Genome-wide gene expression studies of maternal uterine and neonatal cardiac tissues corroborated eNAMPT mAb-induced reductions in inflammatory pathway genes. Discussion: The eNAMPT/TLR4 inflammatory pathway is a highly druggable contributor to IAI pathobiology during pregnancy with the eNAMPT-neutralizing mAb a novel therapeutic strategy to decrease premature delivery and improve short- and long-term neonatal outcomes. eNAMPT blood expression is a potential biomarker for early prediction of chronic lung disease among premature neonates.

Gene profiling reveals the role of inflammation, abnormal uterine muscle contraction and vascularity in recurrent implantation failure

Objective: Recurrent implantation failure (RIF) is now disturbing numerous infertile couples accepting assisted reproductive technology (ART). And the endometrial factors are crucial causes of recurrent implantation failure. However, its mechanism is still unclear. Thus, the aim of this study is to identify altered biologic processes in endometrium that may contribute to recurrent implantation failure. Methods: We recruited two microarray datasets (GSE103465, GSE111974) from Gene Expression Omnibus database (GEO), which contain endometrium from RIF and normal women during implantation period. Using the online tools GEO2R and Venny, we identified Differentially Expressed Genes (DEGs) of selected datasets, and obtained common DEGs. Gene Ontology (GO) terms, Kyoto Encyclopedia of Genes and Genomes (KEGG) and BioCatar pathway enrichment were conducted with Enrichr platform, "ssgsea" and "ggplot2" package of RStudio. PPI networks and hub gene related TF-gene interaction and TF-miRNA co-regulation networks were built via online tools STRING and NetworkAnalyst. Immune infiltration analysis was performed by CIBERSORT platform. Recurrent implantation failure subgroup identification was achieved through "ConsensusClusterPlus," "tsne," "ssgsea", and "ggpubr" package in RStudio. Diagnostic characteristic ROC curves were constructed via "pROC" and "ggplot2" package of RStudio. Enrichr platform was utilized to find drugs targeting hub genes. Results: 26 common DEGs were confirmed. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes/BioCarta analysis determined common DEGs were mainly enriched in inflammation associated pathways including TNF, NF-κB, IL-4, IL-10, IL-6, and TGF-β signaling pathways. Five hub genes (PTGS2, VCAM1, EDNRB, ACTA2, and LIF) and related TF-gene and TF-miRNA interactions were identified. Immune infiltration analysis indicated the importance of macrophage M2 in recurrent implantation failure patients. Importantly, subgroup identification analysis highlighted that recurrent implantation failure patients can be divided into two subgroups with different phenotypes. Moreover, the ROC curves and drugs may provide new diagnostic and therapeutic thought for recurrent implantation failure.

Betamethasone as a potential treatment for preterm birth associated with sterile intra-amniotic inflammation: a murine study

OBJECTIVES

Preterm birth remains the leading cause of perinatal morbidity and mortality worldwide. Preterm birth is preceded by spontaneous preterm labor, which is commonly associated with sterile intra-amniotic inflammation; yet, no approved treatment exists for this clinical condition. Corticosteroids are the standard of care to improve neonatal outcomes in women at risk of preterm birth. Herein, we first validated our model of alarmin-induced preterm birth. Next, we investigated whether treatment with betamethasone could prevent preterm birth resulting from sterile intra-amniotic inflammation in mice.

METHODS

Under ultrasound guidance, the first cohort of dams received an intra-amniotic injection of the alarmin high-mobility group box-1 (HMGB1, n=10) or phosphate-buffered saline (PBS, n=9) as controls. A second cohort of dams received HMGB1 intra-amniotically and were subcutaneously treated with betamethasone (n=15) or vehicle (n=15). Dams were observed until delivery, and perinatal outcomes were observed.

RESULTS

Intra-amniotic HMGB1 reduced gestational length (p=0.04), inducing preterm birth in 40% (4/10) of cases, of which 100% (4/4) were categorized as late preterm births. Importantly, treatment with betamethasone extended the gestational length (p=0.02), thereby reducing the rate of preterm birth by 26.6% (from 33.3% [5/15] to 6.7% [1/15]). Treatment with betamethasone did not worsen the rate of neonatal mortality induced by HMGB1 or alter weight gain in the first three weeks of life.

CONCLUSIONS

Treatment with betamethasone prevents preterm birth induced by the alarmin HMGB1. This study supports the potential utility of betamethasone for treating women with sterile intra-amniotic inflammation.

Immunobiology of Acute Chorioamnionitis

Acute chorioamnionitis is characterized by neutrophilic infiltration and inflammation at the maternal fetal interface. It is a relatively common complication of pregnancy and can have devastating consequences including preterm labor, maternal infections, fetal infection/inflammation, fetal lung, brain, and gastrointestinal tract injury. In this review, we will discuss current understanding of the pathogenesis, immunobiology, and mechanisms of this condition. Most commonly, acute chorioamnionitis is a result of ascending infection with relatively low-virulence organisms such as the Ureaplasma species. Furthermore, recent vaginal microbiome studies suggest that there is a link between vaginal dysbiosis, vaginal inflammation, and ascending infection. Although less common, microorganisms invading the maternal-fetal interface via hematogenous route (e.g., Zika virus, Cytomegalovirus, and Listeria) can cause placental villitis and severe fetal inflammation and injury. We will provide an overview of the knowledge gleaned from different animal models of acute chorioamnionitis and the role of different immune cells in different maternal-fetal compartments. Lastly, we will discuss how infectious agents can break the maternal tolerance of fetal allograft during pregnancy and highlight the novel future therapeutic approaches.

TNF-Signaling Modulates Neutrophil-Mediated Immunity at the Feto-Maternal Interface During LPS-Induced Intrauterine Inflammation

Accumulation of activated neutrophils at the feto-maternal interface is a defining hallmark of intrauterine inflammation (IUI) that might trigger an excessive immune response during pregnancy. Mechanisms responsible of this massive neutrophil recruitment are poorly investigated. We have previously showed that intraamniotic injection of LPS in rhesus macaques induced a neutrophil predominant inflammatory response similar to that seen in human IUI. Here, we demonstrate that anti-TNF antibody (Adalimumab) inhibited ~80% of genes induced by LPS involved in inflammatory signaling and innate immunity in chorio-decidua neutrophils. Consistent with the gene expression data, TNF-blockade decreased LPS-induced neutrophil accumulation and activation at the feto-maternal interface. We also observed a reduction in IL-6 and other pro-inflammatory cytokines but not prostaglandins concentrations in the amniotic fluid. Moreover, TNF-blockade decreased mRNA expression of inflammatory cytokines in the chorio-decidua but not in the uterus, suggesting that inhibition of TNF-signaling decreased the inflammation in a tissue-specific manner within the uterine compartment. Taken together, our results demonstrate a predominant role for TNF-signaling in modulating the neutrophilic infiltration at the feto-maternal interface during IUI and suggest that blockade of TNF-signaling could be considered as a therapeutic approach for IUI, the major leading cause of preterm birth.

Antibiotic administration can eradicate intra-amniotic infection or intra-amniotic inflammation in a subset of patients with preterm labor and intact membranes

BACKGROUND

Intra-amniotic infection is present in 10% of patients with an episode of preterm labor, and is a risk factor for impending preterm delivery and neonatal morbidity/mortality. Intra-amniotic inflammation is often associated with intra-amniotic infection, but is sometimes present in the absence of detectable microorganisms. Antibiotic treatment of intra-amniotic infection has traditionally been considered to be ineffective. Intra-amniotic inflammation without microorganisms has a prognosis similar to that of intra-amniotic infection.

OBJECTIVE

To determine whether antibiotics can eradicate intra-amniotic infection or intra-amniotic inflammation in a subset of patients with preterm labor and intact membranes.

MATERIALS AND METHODS

The study population consisted of women who met the following criteria: 1) singleton gestation between 20 and 34 weeks; 2) preterm labor and intact membranes; 3) transabdominal amniocentesis performed for the evaluation of the microbiologic/inflammatory status of the amniotic cavity; 4) intra-amniotic infection and/or intra-amniotic inflammation; and 5) received antibiotic treatment that consisted of ceftriaxone, clarithromycin, and metronidazole. Follow-up amniocentesis was performed in a subset of patients. Amniotic fluid was cultured for aerobic and anaerobic bacteria and genital mycoplasmas, and polymerase chain reaction was performed for Ureaplasma spp. Intra-amniotic infection was defined as a positive amniotic fluid culture or positive polymerase chain reaction, and intra-amniotic inflammation was suspected when there was an elevated amniotic fluid white blood cell count or a positive result of a rapid test for matrix metalloproteinase-8. For this study, the final diagnosis of intra-amniotic inflammation was made by measuring the interleukin-6 concentration in stored amniotic fluid (>2.6 ng/mL). These results were not available to managing clinicians. Treatment success was defined as eradication of intra-amniotic infection and/or intra-amniotic inflammation or delivery ≥37 weeks.

RESULTS

Of 62 patients with intra-amniotic infection and/or intra-amniotic inflammation, 50 received the antibiotic regimen. Of those patients, 29 were undelivered for ≥7 days and 19 underwent a follow-up amniocentesis. Microorganisms were identified by culture or polymerase chain reaction of amniotic fluid obtained at admission in 21% of patients (4/19) who had a follow-up amniocentesis, and were eradicated in 3 of the 4 patients. Resolution of intra-amniotic infection/inflammation was confirmed in 79% of patients (15/19), and 1 other patient delivered at term, although resolution of intra-amniotic inflammation could not be confirmed after a follow-up amniocentesis. Thus, resolution of intra-amniotic inflammation/infection or term delivery (treatment success) occurred in 84% of patients (16/19) who had a follow-up amniocentesis. Treatment success occurred in 32% of patients (16/50) with intra-amniotic infection/inflammation who received antibiotics. The median amniocentesis-to-delivery interval was significantly longer among women who received the combination of antibiotics than among those who did not (11.4 days vs 3.1 days: P = .04).

CONCLUSION

Eradication of intra-amniotic infection/inflammation after treatment with antibiotics was confirmed in 79% of patients with preterm labor, intact membranes, and intra-amniotic infection/inflammation who had a follow-up amniocentesis. Treatment success occurred in 84% of patients who underwent a follow-up amniocentesis and in 32% of women who received the antibiotic regimen.

IL-1 signaling mediates intrauterine inflammation and chorio-decidua neutrophil recruitment and activation

Neutrophil infiltration of the chorioamnion-decidua tissue at the maternal-fetal interface (chorioamnionitis) is a leading cause of prematurity, fetal inflammation, and perinatal mortality. We induced chorioamnionitis in preterm rhesus macaques by intraamniotic injection of LPS. Here, we show that, during chorioamnionitis, the amnion upregulated phospho-IRAK1-expressed neutrophil chemoattractants CXCL8 and CSF3 in an IL-1-dependent manner. IL-1R blockade decreased chorio-decidua neutrophil accumulation, neutrophil activation, and IL-6 and prostaglandin E2 concentrations in the amniotic fluid. Neutrophils accumulating in the chorio-decidua had increased survival mediated by BCL2A1, and IL-1R blockade also decreased BCL2A1+ chorio-decidua neutrophils. Readouts for inflammation in a cohort of women with preterm delivery and chorioamnionitis were similar to findings in the rhesus macaques. IL-1 is a potential therapeutic target for chorioamnionitis and associated morbidities.

Prostaglandin dehydrogenase is a target for successful induction of cervical ripening

The cervix represents a formidable structural barrier for successful induction of labor. Approximately 10% of pregnancies undergo induction of cervical ripening and labor with prostaglandin (PG) E₂ or PGE analogs, often requiring many hours of hospitalization and monitoring. On the other hand, preterm cervical ripening in the second trimester predicts preterm birth. The regulatory mechanisms of this paradoxical function of the cervix are unknown. Here, we show that PGE₂ uses cell-specific EP2 receptor-mediated increases in Ca²⁺ to dephosphorylate and translocate histone deacetylase 4 (HDAC4) to the nucleus for repression of 15-hydroxy prostaglandin dehydrogenase (15-PGDH). The crucial role of 15-PGDH in cervical ripening was confirmed in vivo. Although PGE₂ or 15-PGDH inhibitor alone did not alter gestational length, treatment with 15-PGDH inhibitor + PGE₂ or metabolism-resistant dimethyl-PGE₂ resulted in preterm cervical ripening and delivery in mice. The ability of PGE₂ to selectively autoamplify its own synthesis in stromal cells by signaling transcriptional repression of 15-PGDH elucidates long sought-after molecular mechanisms that govern PG action in the cervix. This report details unique mechanisms of action in the cervix and serves as a catalyst for (i) the use of 15-PGDH inhibitors to initiate or amplify low-dose PGE₂-mediated cervical ripening or (ii) EP2 receptor antagonists, HDAC4 inhibitors, and 15-PGDH activators to prevent preterm cervical ripening and preterm birth.

Interleukin (IL)-1 in rat parturition: IL-1 receptors 1 and 2 and accessory proteins abundance in pregnant rat uterus at term - regulation by progesterone

The role of interleukin-1 (IL-1), a pro-inflammatory cytokine, in parturition is typically noted by changes in its concentrations. Studying the expression of its receptor family, IL-1 receptor (IL-1R) 1, IL-1R2, IL-1R accessory protein (IL-1RAcP), and its predominantly brain isoform, IL-1RAcPb, during late gestation in the uterus in the Long-Evans rat is another. We assessed changes in their mRNA and protein relative abundance in the uterus and compared IL-1RAcP and IL-1RAcPb mRNA abundance in uterus, cervix, ovaries, placenta, and whole blood of Long-Evans rats during late gestation or in RU486 and progesterone-treated dams using quantitative real-time PCR and western immunoblotting. IL-1R1, IL-1RAcP, and IL-1RAcPb mRNA abundance significantly increased in the uterus at delivery whereas IL-1R2 mRNA abundance significantly decreased. IL-1R1 protein increased at term and IL-1R2 protein decreased at term compared to nonpregnant uteri. IL1-RAcPb mRNA abundance was less than IL-1RAcP, but in the lower uterine segment it was the highest of all tissues examined. RU486 stimulated preterm delivery and an increase in IL-1R1 mRNA abundance whereas progesterone administration extended pregnancy and suppressed the increase in IL-1R1. These data suggest that changes in uterine sensitivity to IL-1 occur during late gestation and suggest another level of regulation for the control of delivery. The roles for IL-1RAcP and IL-1RAcPb need to be determined, but may relate to different intracellular signaling pathways.

Inflammatory Signalling in Fetal Membranes: Increased Expression Levels of TLR 1 in the Presence of Preterm Histological Chorioamnionitis

Histological chorioamnionitis (HCA) is an established marker of ascending infection, a major cause of preterm birth. No studies have characterised the global change in expression of genes involved in the toll-like receptor (TLR) signalling pathways in the presence of HCA in the setting of preterm birth (pHCA). Fetal membranes were collected immediately after delivery and underwent histological staging for inflammation to derive 3 groups; term spontaneous labour without HCA (n = 9), preterm birth <34 weeks gestation without HCA (n = 8) and pHCA <34 weeks (n = 12). Profiling arrays ran in triplicate for each group were used to determine the expression of 84 genes associated with TLR signalling and screen for genes of interest (fold change >2; p<0.1). Expression of identified genes was validated individually for all samples, relative to GAPDH, using RT-PCR. Expression of TLR 1, TLR 2, lymphocyte antigen 96, interleukin 8 and Interleukin-1 receptor-associated kinase-like 2 was increased in pHCA (p<0.05). Degree of expression was positively associated with histological staging of both maternal and fetal inflammation (p<0.05). The inflammatory expression profile at the maternal/fetal interface associated with pHCA, a reflection of ascending infection, is extremely heterogeneous suggesting polymicrobial involvement with activation of a common pathway. Antagonism of TLR 1 and TLR 2 signalling in this setting warrants further assessment.

Neutrophil recruitment and activation in decidua with intra-amniotic IL-1beta in the preterm rhesus macaque

Chorioamnionitis, an infection/inflammation of the fetomaternal membranes, is frequently associated with preterm delivery. The mechanisms of inflammation in chorioamnionitis are poorly understood. We hypothesized that neutrophils recruited to the decidua would be the major producers of proinflammatory cytokines. We injected intra-amniotic (IA) interleukin 1beta (IL-1beta) at ∼80% gestation in rhesus macaque monkeys, Macaca mulatta, delivered the fetuses surgically 24 h or 72 h after IA injections, and investigated the role of immune cells in the chorion-amnion decidua. IA IL-1beta induced a robust infiltration of neutrophils and significant increases of proinflammatory cytokines in the chorioamnion decidua at 24 h after exposure, with a subsequent decrease at 72 h. Neutrophils in the decidua were the major source of tumor necrosis factor alpha (TNFalpha) and IL-8. Interestingly, IA IL-1beta also induced a significant increase in anti-inflammatory indoleamine 2,3-dioxygenase (IDO) expression in the decidua neutrophils. The frequency of regulatory T cells (Tregs) and FOXP3 mRNA expression in the decidua did not change after IA IL-1beta injection. Collectively, our data demonstrate that in this model of sterile chorioamnionitis, the decidua neutrophils cause the inflammation in the gestational tissues but may also act as regulators to dampen the inflammation. These results help to understand the contribution of neutrophils to the pathogenesis of chorioamnionitis-induced preterm labor.

Prostaglandin E2 regulates its own inactivating enzyme, 15-PGDH, by EP2 receptor-mediated cervical cell-specific mechanisms

CONTEXT

Prostaglandins play important roles in parturition and have been used to induce cervical ripening and labor. Prior to cervical ripening at term, 15-hydroxyprostaglandin dehydrogenase (15-PGDH) is highly expressed in the cervix and metabolizes cyclooxygenase-2-mediated increases in active prostaglandin E2 (PGE2) to inactive 15-keto PGE2. At term, 15-PGDH gene expression decreases and PGE2 accumulates, leading to cervical ripening and labor. Previously, we found that the cervical isoform of microphthalmia-associated transcription factor (MiTF-CX) serves as a progestational transcription factor that represses IL-8 and hypoxia-mediated increases in cyclooxygenase-2.

OBJECTIVE

We tested the hypothesis that PGE2 regulates its own inactivation through MiTF-CX.

DESIGN

We used human cervical stromal cells to investigate the regulation of 15-PGDH.

SETTING

This was a laboratory-based study using cells from clinical tissue samples.

MAIN OUTCOME MEASURES

We evaluated the mechanisms by which PGE2 regulates 15-PGDH in human cervical stromal cells.

RESULTS

PGE2 repressed MiTF-CX and 15-PGDH, whereas ectopic overexpression of MiTF-CX induced 15-PGDH expression levels. Stabilization of HIF-1α by deferoxamine resulted in concomitant down-regulation of MiTF-CX and 15-PGDH. Ectopic overexpression of MiTF-CX abrogated PGE2- and deferoxamine-mediated loss of MiTF-CX and 15-PGDH. PGE2-induced loss of MiTF-CX and 15-PGDH was mediated through prostaglandin E2 receptor (EP2) receptors (PTGER2), but not cAMP.

CONCLUSIONS

The 15-PGDH gene is a MiTF-CX target gene in cervical stromal cells and is down-regulated by PGE2 through EP2 receptors. The findings suggest that EP2 receptor-specific antagonists may be used as an adjunct to present clinical management for the prevention of preterm cervical ripening and preterm labor.

Intra-amniotic IL-1β induces fetal inflammation in rhesus monkeys and alters the regulatory T cell/IL-17 balance

Very low birth weight preterm newborns are susceptible to the development of debilitating inflammatory diseases, many of which are associated with chorioamnionitis. To define the effects of chorioamnionitis on the fetal immune system, IL-1β was administered intra-amniotically at ~80% gestation in rhesus monkeys. IL-1β caused histological chorioamnionitis, as well as lung inflammation (infiltration of neutrophils or monocytes in the fetal airways). There were large increases in multiple proinflammatory cytokine mRNAs in the lungs at 24 h postadministration, which remained elevated relative to controls at 72 h. Intra-amniotic IL-1β also induced the sustained expression of the surfactant proteins in the lungs. Importantly, IL-1β significantly altered the balance between inflammatory and regulatory T cells. Twenty-four hours after IL-1β injection, the frequency of CD3(+)CD4(+)FOXP3(+) T cells was decreased in lymphoid organs. In contrast, IL-17A-producing cells (CD3(+)CD4(+), CD3(+)CD4(-), and CD3(-)CD4(-) subsets) were increased in lymphoid organs. The frequency of IFN-γ-expressing cells did not change. In this model of a single exposure to an inflammatory trigger, CD3(+)CD4(+)FOXP3(+) cells rebounded quickly, and their frequency was increased at 72 h compared with controls. IL-17 expression was also transient. Interestingly, the T cell profile alteration was confined to the lymphoid organs and not to circulating fetal T cells. Together, these results suggest that the chorioamnionitis-induced IL-1/IL-17 axis is involved in the severe inflammation that can develop in preterm newborns. Boosting regulatory T cells and/or controlling IL-17 may provide a means to ameliorate these abnormalities.

Inflammation of the fetal ovine skin following in utero exposure to Ureaplasma parvum

There is increasing evidence linking in utero infection and inflammation to preterm birth. Many commensal urogenital tract microorganisms, including the Mycoplasmas and Ureaplasmas, are commonly detected in association with preterm birth. Using an ovine model of sterile fetal inflammation, we demonstrated previously that the fetal skin generates a robust inflammatory response following in utero exposure to lipopolysaccharides from Escherichia coli. The fetal skin's response to colonization of the amniotic fluid by viable microorganisms remains unstudied. We hypothesised that in utero infection with Ureaplasma parvum serovar 3 would induce a proinflammatory response in the fetal skin. We found that (1) cultured fetal keratinocytes (the primary cellular constituent of the epidermis) respond to U. parvum exposure in vitro by increasing the expression of the chemotactant monocyte chemoattractant protein 1 (MCP-1) but not interleukin 1β (IL-1β), IL-6, IL-8, or tumor necrosis factor-α (TNF-α); (2) the fetal skin's response to 7 days of U. parvum exposure is characterized by elevated expression of MCP-1, TNF-α, and IL-10; and (3) the magnitude of inflammatory cytokine/chemokine expression in the fetal skin is dependent on the duration of U parvum exposure. These novel findings provide further support for the role of the fetal skin in the development of fetal inflammation and the preterm birth that may follow.

Interleukin-1 in lipopolysaccharide induced chorioamnionitis in the fetal sheep

We tested the hypothesis that interleukin 1 (IL-1) mediates intra-amniotic lipopolysaccharide (LPS)-induced chorioamnionitis in preterm fetal sheep. Time-mated Merino ewes with singleton fetuses received IL-1α, LPS, or saline (control) by intra-amniotic injection 1 to 2 days before operative delivery at 124 ± 1 days gestational age (N = 5-9/group; term = 150 days). Recombinant human IL-1 receptor antagonist (rhIL-1ra) was given into the amniotic fluid 3 hours before intra-amniotic LPS or saline to block IL-1 signaling. Inflammation in the chorioamnion was determined by histology, cytokine messenger RNA (mRNA), protein expression, and by quantitation of activated inflammatory cells. Intra-amniotic IL-1 and LPS both induced chorioamnionitis. However, IL-1 blockade with IL-1ra did not decrease intra-amniotic LPS-induced increases in pro-inflammatory cytokine mRNAs, numbers of inflammatory cells, myeloperoxidase, or monocyte chemotactic protein-1-expressing cells in the chorioamnion. We conclude that IL-1 and LPS both can cause chorioamnionitis, but IL-1 is not an important mediator of LPS-induced chorioamnionitis in fetal sheep.

Are animal models relevant to key aspects of human parturition?

Preterm birth remains the most serious complication of pregnancy and is associated with increased rates of infant death or permanent neurodevelopmental disability. Our understanding of the regulation of parturition remains inadequate. The scientific literature, largely derived from rodent animal models, suggests two major mechanisms regulating the timing of parturition: the withdrawal of the steroid hormone progesterone and a proinflammatory response by the immune system. However, available evidence strongly suggests that parturition in the human has significantly different regulators and mediators from those in most of the animal models. Our objectives are to critically review the data and concepts that have arisen from use of animal models for parturition and to rationalize the use of a new model. Many animal models have contributed to advances in our understanding of the regulation of parturition. However, we suggest that those animals dependent on progesterone withdrawal to initiate parturition clearly have a limitation to their translation to the human. In such models, a linear sequence of events (e.g., luteolysis, progesterone withdrawal, uterine activation, parturition) gives rise to the concept of a "trigger" mechanism. Conversely, we propose that human parturition may arise from the concomitant maturation of several systems in parallel. We have termed this novel concept "modular accumulation of physiological systems" (MAPS). We also emphasize the urgency to determine the precise role of the immune system in the process of parturition in situations other than intrauterine infection. Finally, we accentuate the need to develop a nonprimate animal model whose physiology is more relevant to human parturition. We suggest that the guinea pig displays several key physiological characteristics of gestation that more closely resemble human pregnancy than do currently favored animal models. We conclude that the application of novel concepts and new models are required to advance translational research in parturition.

Cytokine networks and the regulation of uterine function in pregnancy and parturition

Complex cytokine networks play an important role in a wide range of reproductive and pregnancy related processes. Here, we review the current knowledge concerning the impact of cytokines on uterine physiology and pathophysiology. Cytokines influence a range of uterine functions during the menstrual cycle, implantation, pregnancy and labour. The synergistic interactions between individual cytokines are intricate and dynamic, and modulated by pregnancy hormones. It is not surprising therefore, that perturbations to cytokine signalling are associated with adverse pregnancy outcomes, such as miscarriage, pre-eclampsia, preterm labour and foetal brain injury. Further insight into the complexity of cytokine networks will be required to develop novel therapeutic strategies for the treatment of cytokine imbalances in pregnancy.

Pretreatment with toll-like receptor 4 antagonist inhibits lipopolysaccharide-induced preterm uterine contractility, cytokines, and prostaglandins in rhesus monkeys

Intrauterine infection, which occurs in most early preterm births, triggers an immune response culminating in preterm labor. The authors hypothesize that blockade of lipopolysaccharide (LPS)-induced immune responses by a toll-like receptor 4 antagonist (TLR4A) would prevent elevations in amniotic fluid (AF) cytokines, prostaglandins, and uterine contractility. Chronically catheterized rhesus monkeys at 128 to 147 days' gestation received intra-amniotic infusions of either (1) saline (n = 6), (2) LPS (0.15-10 microg; n = 4), or (3) TLR4A pretreatment with LPS (10 microg) 1 hour later (n = 4). AF cytokines, prostaglandins, and uterine contractility were compared using 1-way ANOVA with Bonferroni-adjusted pairwise comparisons. Compared with saline controls, LPS induced significant elevations in AF interleukin-8 (IL-8), tumor necrosis factor (TNF)- alpha, PGE(2), PGF(2)(alpha), and uterine contractility (P < .05). In contrast, TLR4A pretreatment inhibited LPS-induced uterine activity and was associated with significantly lower AF IL-8, TNF-alpha, PGE(2), and PGF(2)( alpha) versus LPS alone (P < .05). Toll-like receptor antagonists, together with antibiotics, may delay or prevent infection-associated preterm birth.

Immunomodulators plus antibiotics delay preterm delivery after experimental intraamniotic infection in a nonhuman primate model

OBJECTIVE

The purpose of this study was to determine whether treatment with ampicillin together with dexamethasone and indomethacin delays preterm birth that is induced by intraamniotic group B Streptococcus in a nonhuman primate model.

STUDY DESIGN

After contraction onset that was induced by group B Streptococcus (10(6) colony-forming units/mL), chronically instrumented rhesus macaques received either no treatment (controls; n = 6); ampicillin (n = 4); or ampicillin + dexamethasone + indomethacin (n = 5). Outcomes included the interval from contraction onset until delivery and concentrations of amniotic fluid inflammatory mediators.

RESULTS

Mean interval from contraction onset until delivery was 33 +/- 8.7 hours in controls, 82 +/- 28.0 hours with ampicillin (P = .18, vs controls), and 213 +/- 50.8 hours with ampicillin + dexamethasone + indomethacin (P = .004, vs controls). Ampicillin eradicated group B Streptococcus; however, uterine activity, amniotic fluid cytokines, prostaglandins, and matrix metalloproteinase-9 remained elevated. Ampicillin + dexamethasone + indomethacin suppressed interleukin-1beta, tumor necrosis factor-alpha, and prostaglandins E2 and F2alpha but did not alter matrix metalloproteinase expression or chorioamnionitis.

CONCLUSION

The combination of ampicillin + dexamethasone + indomethacin suppressed inflammation and significantly prolonged gestation.

Intraperitoneal infusion of proinflammatory cytokines does not cause activation of the rat uterus during late gestation

Increased concentrations of IL-1beta and TNF-alpha have been associated with parturition. However, the role of these cytokines is unknown. Before parturition, the uterus undergoes a process of activation, during which there are significant changes in expression of genes associated with increased uterine contractility, including the receptors for oxytocin (OT) and prostaglandin (PG)F(2alpha) (FP), PGH(2) synthase isoform 2 (PGHS2), the gap junction protein connexin-43 (Cx-43), and the inducible isoform of nitric oxide synthase (iNOS). To determine whether IL-1beta or TNF-alpha was part of the causal mechanism for increased uterine contractions, we placed osmotic pumps infusing IL-1beta or TNF-alpha into the peritoneal cavity of late pregnant rats (gestation day 19) and measured the effects on uterine contractility and on the uterine concentrations of mRNA for the contraction-associated genes 24 h later. Maternal serum concentrations of IL-1beta and TNF-alpha were increased significantly. By day 21, the control animals had significant increases (P < or = 0.05) in mRNA for OT, FP, PGHS2, and Cx-43, a decrease (P < or = 0.05) in iNOS, and an increase (P < or = 0.05) in uterine sensitivity and responsiveness to OT. Infusion of IL-1beta or TNF-alpha had no effect on uterine contractility or on expression of the activation-associated genes. We conclude that intraperitoneal infusion of IL-1beta or TNF-alpha resulting in significantly increased maternal serum cytokine levels does not cause uterine activation. The role of proinflammatory cytokines in the mechanism of parturition remains unclear.