Immunmodulating cytokines induce term and preterm parturition

Two patterns of cytokine production by placental macrophages

INTRODUCTION

Macrophages participate in the regulation immune and morphogenetic events in the placenta. However, these roles remain unclear for placental macrophages (Hofbauer cells). The aims of this study were to characterize the consecutive steps of cytokine production (intracellular synthesis and secretion) in placental macrophages in early and late gestation and to compare the secretory profiles of placental macrophages and villous tissue.

METHODS

Macrophages and villous tissue were isolated from placentas obtained from normal pregnancies at either 9-12 or 38-40 weeks of gestation. Intracellular cytokines were determined by flow cytometry after staining with monoclonal antibodies. Secreted cytokines were quantified by cytometric bead array and ELISA.

RESULTS

Two patterns of cytokine production were revealed in placental macrophages. Cytokines in the first group (IL-1, IL-6, IL-8, IL-10, TNFα) demonstrated low basal production and were stimulated by bacterial endotoxin. Cytokines in the second group (IL-11, IL-17A, IL-17F, TGF-β, VEGF) were characterized by constitutive production and did not respond to stimulation. Gestational age-dependent changes were observed: basal secretion of TNFα and IL-8 increased whereas IL-11 and IL-17 secretion decreased in third-trimester macrophages compared with the first-trimester cells. Comparison of cytokine production at the cellular and tissue levels suggested the contribution of the placental macrophages both in intraplacental and extraplacental cytokine production.

DISCUSSION

It would be safe to assume that the two patterns of cytokine production, revealed in our study, correspond to two regulatory roles of placental macrophages: "immune" and "morphogenetic". The inflammatory phenotype of macrophages is attenuated in early gestation and increases with the progression of pregnancy. The cytokines of the first group supposedly contribute to both local and extraplacental levels, whereas the cytokine effects of the second group are more likely confined to the placental tissue.

A pronounced uterine pro-inflammatory response at parturition is an ancient feature in mammals

Regulating maternal immunity is necessary for successful human pregnancy. Whether this is needed in mammals with less invasive placentation is subject to debate. Indeed, the short gestation times in marsupials have been hypothesized to be due to a lack of immune regulation during pregnancy. Alternatively, the maternal marsupial immune system may be unstimulated in the absence of a highly invasive placenta. Transcripts encoding pro-inflammatory cytokines were found to be overrepresented in the whole uterine transcriptome at terminal pregnancy in the opossum, Monodelphis domestica To investigate this further, immune gene transcripts were quantified throughout opossum gestation. Transcripts encoding pro-inflammatory cytokines remained relatively low during pre- and peri-attachment pregnancy stages. Levels dramatically increased late in gestation, peaking within 12 h prior to parturition. These results mirror the spike of inflammation seen at eutherian parturition but not at attachment or implantation. Our results are consistent with the role of pro-inflammatory cytokines at parturition being an ancient and conserved birth mechanism in therian mammals.

The bacterial etiology of preterm birth

Preterm birth is the leading cause of infant morbidity and mortality. Very preterm births, those occurring before 32 completed weeks of gestation, are associated with the greatest risks. The leading cause of very preterm birth is intrauterine infection, which can lead to an inflammatory response that triggers labor or preterm premature rupture of membranes. How bacteria invade the uterine cavity, which is normally a sterile environment, and the reasons why different species vary in their capacity to induce inflammation and preterm birth are still incompletely understood. However, advanced techniques that circumvent the need for cultivating bacteria, deep sequence analysis that allows for the comprehensive characterization of the microbiome of a given body site and detection of low-prevalence species, and transcriptomics and metabolomics approaches that shed light on the host response to bacterial invasion are all providing a more complete picture of the progression from vaginal colonization to uterine invasion to preterm labor and preterm birth.

A new approach to oxidative stress and inflammatory signaling during labour in healthy mothers and neonates

The objective of the current study was to investigate for the first time and simultaneously the oxidative stress and inflammatory signaling induced during the delivery in healthy mothers and their neonates. 56 mothers with normal gestational course and spontaneous delivery were selected. Blood samples were taken from mother (before and after delivery) both from vein and artery of umbilical cord. Lower antioxidant enzymes activities were observed in neonates compared with their mothers and lower oxidative stress in umbilical cord artery with respect to vein. There was an overexpression of inflammatory cytokines in the mother, such as IL-6 and TNF-α, and, in addition, PGE₂ was also increased. Neonates showed lower levels of IL-6 and TNF-α and higher values of sTNF-RII and PGE₂ in comparison with their mothers. Parturition increases oxidative damage in the mother, although the indicators of oxidative damage were lower in umbilical cord artery with respect to umbilical vein. The overexpression of inflammatory cytokines reveals that fetus suffers its own inflammatory process during parturition.

The timing of cord clamping and oxidative stress in term newborns

BACKGROUND

Clamping and cutting of the umbilical cord is the most prevalent of all operations, but the optimal timing of cord clamping is controversial, with different timings offering advantages and disadvantages. This study, for the first time, compares the influence of early and late cord clamping in correlation with oxidative stress and inflammation signaling, Because cord clamping timing may have a significant influence on placenta-to-infant blood transfer, thereby modifying oxygenation of maternal and fetal tissues, and on the transfer of inflammatory mediators throughout the placenta.

METHODS

Sixty-four pregnant subjects were selected at the Gynecology and Obstetrics Services Department of the Clinico San Cecilio Hospital, Granada, Spain, based on disease-free women who experienced a normal course of pregnancy and a spontaneous, vaginal, single delivery. Half of the subjects had deliveries with early-clamped newborn infants (at 10 s), and the other half had late-clamped deliveries (at 2 min).

RESULTS

Erythrocyte catalase activity was significantly greater in the late-clamped group than in the early-clamped group (P < .01 for the umbilical vein and P < .001 for the artery). The values for superoxide dismutase, total antioxidant status, and soluble tumor necrosis factor receptor II were all significantly higher in the late-clamped group compared with the early-clamped group (P < .01, P < .001, and P < .001, respectively).

CONCLUSIONS

The results suggest a beneficial effect of late cord clamping, produced by an increase in antioxidant capacity and moderation of the inflammatory-mediated effects induced during delivery of term neonates.

Transcriptome interrogation of human myometrium identifies differentially expressed sense-antisense pairs of protein-coding and long non-coding RNA genes in spontaneous labor at term

OBJECTIVE

To identify differentially expressed long non-coding RNA (lncRNA) genes in human myometrium in women with spontaneous labor at term.

MATERIALS AND METHODS

Myometrium was obtained from women undergoing cesarean deliveries who were not in labor (n = 19) and women in spontaneous labor at term (n = 20). RNA was extracted and profiled using an Illumina® microarray platform. We have used computational approaches to bound the extent of long non-coding RNA representation on this platform, and to identify co-differentially expressed and correlated pairs of long non-coding RNA genes and protein-coding genes sharing the same genomic loci.

RESULTS

We identified co-differential expression and correlation at two genomic loci that contain coding-lncRNA gene pairs: SOCS2-AK054607 and LMCD1-NR_024065 in women in spontaneous labor at term. This co-differential expression and correlation was validated by qRT-PCR, an experimental method completely independent of the microarray analysis. Intriguingly, one of the two lncRNA genes differentially expressed in term labor had a key genomic structure element, a splice site, that lacked evolutionary conservation beyond primates.

CONCLUSIONS

We provide, for the first time, evidence for coordinated differential expression and correlation of cis-encoded antisense lncRNAs and protein-coding genes with known as well as novel roles in pregnancy in the myometrium of women in spontaneous labor at term.

Characterization of the myometrial transcriptome in women with an arrest of dilatation during labor

OBJECTIVE

The molecular basis of failure to progress in labor is poorly understood. This study was undertaken to characterize the myometrial transcriptome of patients with an arrest of dilatation (AODIL).

STUDY DESIGN

Human myometrium was prospectively collected from women in the following groups: (1) spontaneous term labor (TL; n=29) and (2) arrest of dilatation (AODIL; n=14). Gene expression was characterized using Illumina® HumanHT-12 microarrays. A moderated Student's t-test and false discovery rate adjustment were used for analysis. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) of selected genes was performed in an independent sample set. Pathway analysis was performed on the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway database using Pathway Analysis with Down-weighting of Overlapping Genes (PADOG). The MetaCore knowledge base was also searched for pathway analysis.

RESULTS

(1) Forty-two differentially expressed genes were identified in women with an AODIL; (2) gene ontology analysis indicated enrichment of biological processes, which included regulation of angiogenesis, response to hypoxia, inflammatory response, and chemokine-mediated signaling pathway. Enriched molecular functions included transcription repressor activity, heat shock protein (Hsp) 90 binding, and nitric oxide synthase (NOS) activity; (3) MetaCore analysis identified immune response chemokine (C-C motif) ligand 2 (CCL2) signaling, muscle contraction regulation of endothelial nitric oxide synthase (eNOS) activity in endothelial cells, and triiodothyronine and thyroxine signaling as significantly overrepresented (false discovery rate <0.05); (4) qRT-PCR confirmed the overexpression of Nitric oxide synthase 3 (NOS3); hypoxic ischemic factor 1A (HIF1A); Chemokine (C-C motif) ligand 2 (CCL2); angiopoietin-like 4 (ANGPTL4); ADAM metallopeptidase with thrombospondin type 1, motif 9 (ADAMTS9); G protein-coupled receptor 4 (GPR4); metallothionein 1A (MT1A); MT2A; and selectin E (SELE) in an AODIL.

CONCLUSION

The myometrium of women with AODIL has a stereotypic transcriptome profile. This disorder has been associated with a pattern of gene expression involved in muscle contraction, an inflammatory response, and hypoxia. This is the first comprehensive and unbiased examination of the molecular basis of an AODIL.

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.

Serum markers for prediction of spontaneous preterm delivery in preterm labour

BACKGROUND

Simple, more sensitive markers to predict spontaneous preterm delivery in preterm labour are needed. The aim of this study is to compare the clinical effectiveness of various serum inflammatory markers and cervix length for prediction of spontaneous preterm delivery.

MATERIALS AND METHODS

We retrospectively reviewed medical records of 175 patients hospitalized for preterm labour (102 with preterm delivery and 73 with term delivery). For all study subjects, haematological markers and cervix length were recorded on admission. Because neutrophil to lymphocyte ratio (NLR) showed the potential as a diagnostic marker, we designed a combined marker by dividing cervix length by NLR. The diagnostic and prognostic accuracy of the combined marker was analysed using multivariate analyses.

RESULTS

The levels of combined marker (P < 0·001), neutrophil (P < 0·001), lymphocyte (P = 0·02), NLR (P < 0·001), C-reactive protein (P = 0·016) and the cervix length (P < 0·001) in preterm delivery group were significantly different from those of term delivery group. Compared to cervix length or systemic inflammatory markers alone, combined marker showed higher sensitivity (64·2%) and specificity (88·3%) for prediction of preterm delivery. On Cox multivariate analysis, combined marker positive (< 0·29) and short cervix length (< 1·7 cm) were independent poor prognostic factors and combined marker positive was the most powerful prognostic marker for spontaneous preterm delivery (hazard ratio = 5·60, P < 0·001).

CONCLUSIONS

Combined marker could be used as a simple and sensitive parameter for identifying women at risk of spontaneous preterm delivery.

Periodontal disease and bacterial vaginosis as genetic and environmental markers for the risk of spontaneous preterm labor and preterm birth

OBJECTIVE

The aim of this study was to review the evidence associating periodontal disease, and bacterial vaginosis with preterm birth, and the link with gene polymorphism, as well as the preventions and interventions which might reduce the risk of spontaneous preterm labor and preterm births in women with periodontal disease and/or bacterial vaginosis.

BACKGROUND

Preterm birth accounts for 70% of perinatal mortality, nearly 50% of long term neurological morbidity, and a significant impact on health care costs. There is evidence that spontaneous preterm labor and preterm birth are associated with intrauterine infection due to abnormal genital and/or oral colonization. Periodontal disease and bacterial vaginosis share microbiological similarities, and both conditions are associated with spontaneous preterm labor and preterm birth. In addition, periodontal disease and bacterial vaginosis have been linked through gene polymorphism.

METHODS

A review of the literature using widely accepted scientific search engines in English language.

RESULTS

Studies evaluating antibiotic administration to eradicate periodontal disease and/or bacterial vaginosis responsible organisms, and minimize the risk of preterm births have yielded conflicting results. With respect to bacterial vaginosis, the timing and the choice of antibiotic administration might partly explain the conflicting results. The use of scaling and/or root planning for women with periodontal disease appears to reduce the risk of preterm birth, but routine administration of antibiotics has not demonstrated any impact on preterm birth.

CONCLUSION

Prospective studies evaluating the association of gene polymorphism with preterm birth, and the contribution of periodontal disease and bacterial vaginosis are needed.

Differing prevalence and diversity of bacterial species in fetal membranes from very preterm and term labor

BACKGROUND

Intrauterine infection may play a role in preterm delivery due to spontaneous preterm labor (PTL) and preterm prolonged rupture of membranes (PPROM). Because bacteria previously associated with preterm delivery are often difficult to culture, a molecular biology approach was used to identify bacterial DNA in placenta and fetal membranes.

METHODOLOGY/PRINCIPAL FINDINGS

We used broad-range 16S rDNA PCR and species-specific, real-time assays to amplify bacterial DNA from fetal membranes and placenta. 74 women were recruited to the following groups: PPROM <32 weeks (n = 26; 11 caesarean); PTL with intact membranes <32 weeks (n = 19; all vaginal birth); indicated preterm delivery <32 weeks (n = 8; all caesarean); term (n = 21; 11 caesarean). 50% (5/10) of term vaginal deliveries were positive for bacterial DNA. However, little spread was observed through tissues and species diversity was restricted. Minimal bacteria were detected in term elective section or indicated preterm deliveries. Bacterial prevalence was significantly increased in samples from PTL with intact membranes [89% (17/19) versus 50% (5/10) in term vaginal delivery p = 0.03] and PPROM (CS) [55% (6/11) versus 0% (0/11) in term elective CS, p = 0.01]. In addition, bacterial spread and diversity was greater in the preterm groups with 68% (13/19) PTL group having 3 or more positive samples and over 60% (12/19) showing two or more bacterial species (versus 20% (2/10) in term vaginal deliveries). Blood monocytes from women with PTL with intact membranes and PPROM who were 16S bacterial positive showed greater level of immune paresis (p = 0.03). A positive PCR result was associated with histological chorioamnionitis in preterm deliveries.

CONCLUSION/SIGNIFICANCE

Bacteria are found in both preterm and term fetal membranes. A greater spread and diversity of bacterial species were found in tissues of women who had very preterm births. It is unclear to what extent the greater bacterial prevalence observed in all vaginal delivery groups reflects bacterial contamination or colonization of membranes during labor. Bacteria positive preterm tissues are associated with histological chorioamnionitis and a pronounced maternal immune paresis.

Characterization of cytokine production by human term placenta macrophages in vitro

PROBLEM

Macrophages are apparently the only immune cells within placenta villi, yet functions of these cells remain obscure. It has been postulated that placental macrophages accomplish regulatory roles at the fetal-maternal interface by means of wide variety of secreted cytokines. We attempt to analyze the patterns of cytokine production in an isolated population of placental macrophages.

METHOD OF STUDY

Macrophages were obtained from term placentas in the absence of spontaneous labor. The basal and lipopolysaccharide (LPS)-stimulated levels of intracellular cytokines were detected by flow cytometry. The basal cytokine secretion was determined by BD Cytometry Bead Array (BD Biosciences, San Diego, CA, USA).

RESULTS

Intracellular IL-1alpha, IL-1beta, IL-6, and TNFalpha were detected in 31, 27, 4, and 3% CD68+ cells, respectively. Stimulation with LPS increased the proportions of cytokine-producing CD68+ cells to 48, 50, 28, and 49%, respectively. Under basal conditions, levels of released TNFalpha and IL-6, respectively, were 20- and 25-fold higher when compared with IL-1b while IL-10 was secreted in small but detectable amounts. When a secretory activity was estimated for cytokine-producing cells, the secretion rate for TNFalpha and IL-6 overwhelmingly surpassed that for IL-1beta (TNFalpha:IL-6:IL-1beta ratio was 192:145:1).

CONCLUSION

These results suggest functional heterogeneity of the placental macrophage population and contribute to the elucidation of regulatory roles of these cells in gestation.

Amniotic fluid interleukin-6 and tumor necrosis factor-alpha at mid-trimester genetic amniocentesis: relationship to intra-amniotic microbial invasion and preterm delivery

OBJECTIVE

To determine the value of amniotic fluid interleukin-6 (AF IL-6) and tumor necrosis factor-alpha (AF TNF-alpha) in the diagnosis of microbial invasion of the amniotic cavity and in the prediction of preterm delivery (PTD).

STUDY DESIGN

Following amniocentesis, a sample of amniotic fluid was sent for aerobic and anaerobic bacterial cultures along with Ureaplasma urealyticum culture and it was also assessed for IL-6 and TNF-alpha.

RESULTS

Forty-eight women who delivered preterm (<37 weeks) were matched with 96 controls. The AF IL-6 and TNF-alpha concentrations of women with spontaneous PTD were significantly higher than those who delivered at term (IL-6: 176.3 pg/ml [130.6-208.6] vs. 52.3 pg/ml [37.2-92.3]; TNF-alpha: 8.8 pg/ml [7.2-10.7] vs. 5.5 pg/ml [5.0-6.3]). AF IL-6 and TNF-alpha concentrations of >99.3 pg/ml and of >6.6 pg/ml respectively, had a sensitivity of 89.6% and 81.3% and a specificity of 80.3% and 79.2% for the prediction of spontaneous PTD. Moreover, AF IL-6 and TNF-alpha concentrations of >99.3 pg/ml and of 6.3 pg/ml respectively, had a sensitivity of 91.9% and 78.4% and a specificity of 73.8% and 70.1% for the prediction of a positive AF culture.

CONCLUSIONS

Elevated mid-trimester concentrations of AF IL-6, or/and of TNF-alpha can identify women at risk for intra-amniotic infection and for spontaneous PTD.

Physiology and pathophysiology of canonical transient receptor potential channels

The existence of a mammalian family of TRPC ion channels, direct homologues of TRP, the visual transduction channel of flies, was discovered during 1995-1996 as a consequence of research into the mechanism by which the stimulation of the receptor-Gq-phospholipase Cbeta signaling pathway leads to sustained increases in intracellular calcium. Mammalian TRPs, TRPCs, turned out to be nonselective, calcium-permeable cation channels, which cause both a collapse of the cell's membrane potential and entry of calcium. The family comprises 7 members and is widely expressed. Many cells and tissues express between 3 and 4 of the 7 TRPCs. Despite their recent discovery, a wealth of information has accumulated, showing that TRPCs have widespread roles in almost all cells studied, including cells from excitable and nonexcitable tissues, such as the nervous and cardiovascular systems, the kidney and the liver, and cells from endothelia, epithelia, and the bone marrow compartment. Disruption of TRPC function is at the root of some familial diseases. More often, TRPCs are contributing risk factors in complex diseases. The present article reviews what has been uncovered about physiological roles of mammalian TRPC channels since the time of their discovery. This analysis reveals TRPCs as major and unsuspected gates of Ca(2+) entry that contribute, depending on context, to activation of transcription factors, apoptosis, vascular contractility, platelet activation, and cardiac hypertrophy, as well as to normal and abnormal cell proliferation. TRPCs emerge as targets for a thus far nonexistent field of pharmacological intervention that may ameliorate complex diseases.

V-chain preference of gamma/delta T-cell receptors in peripheral blood during term labor

PROBLEM

An altered function of the maternal immune system creates a favorable environment for the developing fetus during pregnancy. At term, new regulatory mechanisms are activated, to initiate labor. Earlier we showed that in peripheral blood of pregnant women gamma/delta T cells of cytotoxic phenotype are replaced by those of a non-cytotoxic phenotype. Here we studied the Vgamma and Vdelta chain usage of peripheral gamma/delta T cells from women in labor.

METHOD OF STUDY

Vgamma and Vdelta chain expression on peripheral blood lymphocytes obtained at the 3rd trimester of pregnancy and during parturition were examined by immuncytochemistry and flow cytometry.

RESULTS

Increased % of Vgamma9/Vdelta2 and decreased % of Vgamma4/Vdelta1 T cells were found in peripheral blood during labor, together with unaltered percentages of single Vgamma+ or Vdelta+ cells. The initially high Vgamma4/Vdelta1 to Vgamma9/Vdelta2 ratio decreased during labor.

CONCLUSION

The initiation of labor is characterized by an altered V-chain usage of gamma/delta T cells.

In vitro secretion profiles of interleukin (IL)-1beta, IL-6, IL-8, IL-10, and TNF alpha after selective infection with Escherichia coli in human fetal membranes

BACKGROUND

Chorioamniotic membranes infection is a pathologic condition in which an abnormal secretion of proinflammatory cytokines halts fetal immune tolerance. The aim of the present study was to evaluate the functional response of human chorioamniotic membranes, as well as the individual contribution of the amnion and choriodecidua after stimulation with Escherichia coli, a pathogen associated with preterm labor.

METHODS

Explants of chorioamniotic membranes from 10 women (37-40 weeks of gestation) were mounted and cultured in a Transwell system, which allowed us to test the amnion and choriodecidua compartments independently. Escherichia coli (1 x 10 6 CFU/mL) was added to either the amniotic or the choriodecidual regions or both; after a 24-h incubation, the secretion of IL-1beta, IL-6, TNFalpha, IL-8, and IL-10 in both compartments was measured using a specific ELISA. Data were analyzed by Kruskal-Wallis one-way analysis of variance.

RESULTS

After stimulation with Escherichia coli, the choriodecidua compartment showed an increase in the secretion of IL-1beta (21-fold), IL-6 (2-fold), IL-8 (6-fold), and IL-10 (37-fold), regardless of which side of the membrane was stimulated; TNFalpha secretion augmented (22-fold) also but only when the stimulus was applied simultaneously to both sides. When the amnion was stimulated directly, the level of IL-1beta (13-fold) rose significantly; however, the increase in IL-8 secretion was larger (20-fold), regardless of the primary site of infection. TNFalpha secretion in the amnion compartment rose markedly only when Escherichia coli was simultaneously applied to both sides.

CONCLUSION

Selective stimulation of fetal membranes with Escherichia coli results in a differential production of IL-1beta, IL-6, TNFalpha, IL-8, and IL-10. These tissues were less responsive when the amnion side was stimulated. This is in agreement with the hypothesis that the choriodecidua may play a primary role during an ascending intrauterine infection, being the main barrier to progression of the infection into the amniotic cavity. Therefore, the tissue-specific capacities for the secretion of these immune modulators could be a determining factor for the degree of severity of the inflammation process in fetal membranes.

Spontaneous and LPS-induced secretion of cytokines by villous chorion tissue

Secretion of IL-1alpha, IL-1beta, IL-6, IL-10, and TNF-alpha cytokines by villous chorion cultures (7-14 weeks) during normal pregnancy and in spontaneous abortions was studied. Secretion of IL-1alpha and IL-6 increased 4.5 and 7.3 times in miscarriages, while secretion of IL-1beta, IL-10, and TNF-alpha decreased. LPS stimulated the production of IL-1alpha and IL-6 in samples obtained during surgical abortion. LPS stimulated IL-1alpha and TNF-alpha secretion in miscarriages, while the level of IL-6 production decreased significantly. It is hypothesized that increased production of IL-1alpha and IL-6 and attenuation of the antiinflammatory effect of IL-10 play an important role in the pathogenesis of miscarriages at early stages of gestation. The results suggest that cytokine regulation of the fetus rejection is different at early and late stages of gestation.

Management of preterm prelabour rupture of membranes: an audit. How do the results compare with clinical practice guidelines?

BACKGROUND

Preterm prelabour rupture of membranes is a common clinical event. It is associated with infection in approximately 50% of cases. Clinical practice guidelines have been developed at the Royal Women's Hospital, Melbourne, Australia for investigation and management of this condition.

AIM

To perform an audit of management of women presenting with this diagnosis and assess how inpatient management compares with the Hospital's current clinical practice guideline and how the clinical practice guideline compares with the evidence in the literature.

METHODS

Retrospective audit over a 3-month period collecting data on maternal age, gestation, microbiological results, other investigations, pharmacological treatment and outcome.

RESULTS

All the 56 women admitted for this reason received at least one dose of antibiotic, most commonly erythromycin. More than two thirds of patients had the antibiotic changed at least once during their admission. Ten patients were prescribed intravenous antibiotics without a clear indication. Sixty-four percent received steroids for lung maturation of the neonate and 30% received tocolysis with nifedipine. Almost two thirds of patients delivered within 7 days and there were four neonatal deaths.

CONCLUSION

In general management of women with premature rupture of membranes is in keeping with the current clinical practice guideline at the Royal Women's Hospital although antibiotic prescribing and management of Group B streptococcus colonisation could be improved. In addition, routine measurement of C reactive protein should cease. The current clinical practice guideline should be modified to reflect the current evidence in the literature.

The role of nuclear factor kappa B in human labour

Preterm birth remains the leading cause of perinatal mortality and morbidity, largely as a result of a poor understanding of the precise mechanisms controlling labour onset in humans. Inflammation has long been recognised as a key feature of both preterm and term labour, with an influx of inflammatory cells into the uterus and elevated levels of pro-inflammatory cytokines observed during parturition. Nuclear factor kappa B (NF-κB) is a transcription factor family classically associated with inflammation. Accumulating evidence points to a role for NF-κB in the physiology and pathophysiology of labour. NF-κB activity increases with labour onset and is central to multiple prolabour pathways. Premature or aberrant activation of NF-κB may thus contribute to preterm labour. The current understanding of NF-κB in the context of human labour is discussed here.

Prolonged preterm rupture of fetal membranes, a consequence of an increased maternal anti-fetal T cell responsiveness

A fetus, although semi-allogeneic, is usually accepted by the maternal immune system. However, complications, including alloresponsive mechanisms, are thought to be potentially detrimental for a successful pregnancy. Therefore, we compared allogeneic T cell responses of nonpregnant women with the response of healthy pregnant women and pregnant women who have various gestation-associated diseases. Peripheral blood mononuclear cells (PBMCs) of all three groups were stimulated with PBMCs from unrelated volunteers. Pregnant women had significantly reduced stimulation indices (SIs) compared with nonpregnant women. Exposing PBMCs from pregnant women to PBMCs of their own fetus led to a further significant decrease of SIs. Among the two groups of pregnant individuals, SIs of women with prolonged preterm rupture of fetal membranes (PPROM) were significantly higher when the maternal PBMCs were stimulated with PBMCs of their own fetus. This phenomenon could not be observed after stimulation with PBMCs from unrelated volunteers. In addition, an increased humoral immune response was assessed for women with PPROM in comparison with women with uncontrollable preterm labor. Our results revealed a strongly reduced allogeneic T cell response of PBMCs from pregnant women that was further down-regulated when PBMCs from their own fetus were used as stimulators. By contrast, data from women with PPROM suggest an increased maternal T cell response specifically toward the fetal HLA antigens.

Maternal infection and adverse fetal and neonatal outcomes

Adverse pregnancy outcomes can follow direct placental, fetal, or neonatal infection, or preterm birth associated with vaginal, cervical, intrauterine, or even nonpelvic infections. These latter infections appear to be associated with the majority of very early preterm births, and may explain some of the long-term neurologic damage associated with preterm birth. Bacterial vaginosis and its associated intrauterine infections likely contribute far more to the overall burden of adverse pregnancy outcomes than the more classical perinatal infections such as rubella and syphilis.

Cytokines in the oviparity/viviparity transition: evidence of the interleukin-1 system in a species with reproductive bimodality, the lizard Lacerta vivipara

Placental viviparity is a reproductive strategy usually attributed to mammals. However, it is also present in other vertebrate species, e.g. in Squamate reptiles. Although the immunological mechanisms that allow the survival of the semi-allogenic embryo in maternal tissues are still largely unknown, cytokines seem to play an important role in mammalian reproduction. Previous studies in our laboratory showed that interleukin-1 (IL-1), a cytokine associated with implantation in mice, is also expressed at the materno-fetal interface of placental viviparous Squamates. In this study, we used the model of Lacerta vivipara, which exhibits reproductive bimodality, that is, the coexistence of oviparous and viviparous populations. By means of immunohistochemistry and anti-human antibodies, we showed that uterine tissues of L. vivipara (seven oviparous and six viviparous animals) expressed the two IL-1 isoforms, IL-1alpha and IL-1beta, and the type I IL-1 receptor (IL-1R tI) both at the pre-ovulatory stage and during gestation, with no significant difference between oviparous and viviparous females. In L. vivipara, as in most oviparous Squamates, an important phase of embryonic development takes place in the mother's oviduct, before egg-laying. Moreover, although thinner than in oviparous females, an eggshell membrane persists throughout gestation in viviparous females also, which develop a very simple type of placenta. The data suggest that immunological mechanisms that allow the survival of the semi-allogenic embryo in maternal tissues are independent of the timing or intimacy of contact between maternal and fetal tissues.

A review of the role of proinflammatory cytokines in labor and noninfectious preterm labor

The prevention of preterm labor has the potential to reduce newborn morbidity and mortality by decreasing the incidence of preterm birth. Half of all preterm births occur in women with no known clinical risk factors. Labor onset and progress is multifactorial, and we are just beginning to understand the role of cytokines in uterine activity. The purpose of this article is to review the role of cytokines in labor and preterm labor not associated with infection and to provide implications for research and practice.

Tumor necrosis factor-alpha suppresses the expression of steroid receptor coactivator-1 and -2: a possible mechanism contributing to changes in steroid hormone responsiveness

Inflammation is associated in some tissues with diminished responsiveness to steroid hormone action. We hypothesized that proinflammatory cytokines alter steroid hormone sensitivity, in part, by reducing levels of key nuclear receptor coactivators. Treatment of cultured human uterine smooth muscle cells (UtSMC) with TNF-alpha significantly reduced mRNA for the coactivators, SRC-1 (42%, P<0.01) and 2 (47%, P<0.03), and diminished the respective protein levels, but did not significantly alter the mRNAs encoding SRC-3, CBP and the corepressors, NCoR and SMRT; or progesterone receptor protein levels. To assess TNF-alpha effects on steroid hormone-mediated transcriptional activity, UtSMC were transfected with progesterone receptor B (PR-B) and a model PRE2-luciferase reporter construct. Transfected UtSMC were treated with progesterone alone or in the presence of TNF-alpha, and assayed for luciferase activity. TNF-alpha (10 ng/ml) diminished progesterone-stimulated PR-B-mediated transactivation by approximately 60% (P<0.02). The TNF-alpha-dependent decrease in PRE-luciferase activity was fully prevented by cotransfection with SRC-2, and partially prevented with exogenous SRC-1. In conclusion, TNF-alpha impairs progesterone-stimulated PR-B-mediated transactivation, and these effects appear to be due, in part, to reduced expression of SRC-1 and -2, which is a novel mechanism by which inflammation can functionally block steroid hormone action.

Secretions of interleukin-1beta and tumor necrosis factor alpha by whole fetal membranes depend on initial interactions of amnion or choriodecidua with lipopolysaccharides or group B streptococci

The present study evaluated the secretions of interleukin (IL)-1beta and tumor necrosis factor (TNF) alpha by fetal membranes stimulated with group B streptococci (GBS) and lipopolysaccharide (LPS). The aim was to evaluate the initial response of full-thickness membranes to the microbial insult using an in vitro experimental model that allowed testing of the individual contributions of amnion and choriodecidua to stimulation. Full-thickness membranes were obtained after delivery by elective cesarean section from women at 37-40 wk of gestation without evidence of active labor. The membranes were mounted in Transwell devices, physically separating the upper and lower chambers. The LPS (500 ng/ml) or GBS (1 x 10(6) colony-forming units/ml) was added to either the amniotic or choriodecidual surface, and accumulation of IL-1beta and TNFalpha were measured in both compartments using a specific ELISA. Fetal membranes followed different patterns of secretion of proinflammatory cytokines that depended on the side to which the stimulus was added or the nature of the stimulus itself. The TNFalpha was secreted by amnion and choriodecidua in the presence of LPS or GBS, and stimulation with GBS induced a greater synthesis of IL-1beta than did stimulation with LPS. Choriodecidual tissue was more responsive than amniotic tissue, and this response tended to be higher even when the stimulation was only on the amniotic side. However, the amnion plays an active role in recognizing LPS or GBS, contributing a significant amount of TNFalpha. Thus, cooperative and bidirectional communications occur between amnion and choriodecidua in response to bacterial products, which include intermembranous cytokine traffic and signaling between tissues.

Physiological induction of transient receptor potential canonical proteins, calcium entry channels, in human myometrium: influence of pregnancy, labor, and interleukin-1 beta

This study investigated gestational regulation of transient receptor potential canonical (TrpC) proteins, putative calcium entry channels in human myometrium, and the potential modulation of TrpC expression by IL-1 beta, a cytokine implicated in labor. Total RNA and proteins were isolated from myometrial biopsies obtained from NP women, pregnant women at term not in labor (TNL), or term active labor (TAL) and from primary cultured human myometrial smooth muscle cells incubated with IL-1 beta or IL-1 beta with or without nimesulide. Semiquantitative RT-PCR demonstrated significant up-regulation of TrpC1 in TAL and TNL (P < or = 0.01) and TrpC6 (P < or = 0.01) and TrpC7 (P < or = 0.05) in TAL samples. TrpC3 and TrpC4 mRNA expression was unaffected. Western blot demonstrated significant up-regulation of TrpC1 in TAL and TNL (P < or = 0.05) and TrpC3 (P < or = 0.01), TrpC4 (P < or = 0.05), and TrpC6 (P < or = 0.01) in TAL samples. IL-1 beta did not alter TrpC1, 3, 4, 6, or 7 mRNA expression; but IL-1 beta exclusively up-regulated TrpC3 protein expression (P < or = 0.05). TrpC3 up-regulation was unaffected by cyclooxygenase blockade. These data demonstrate physiological regulation of TrpC mRNA and protein and suggest an important role for TrpC proteins in human myometrium during labor.

Psychological and physiological stress: impact on preterm birth

Stress increases corticotropin-releasing hormone and may ultimately result in increased uterine contractility. Stress also increases cytokine production, which independently may lead to preterm birth or increase susceptibility to infection, thereby increasing the risk of preterm birth. Finally, stress may change health behaviors that lead to preterm birth. Research findings on the relationship between stress and preterm birth have been contradictory. In this article, the authors propose a model of the relationship between stress and preterm birth, evaluate the research on stress and pregnancy outcomes, and discuss the implications for nursing practice and research.

Immunology of term and preterm labor

During pregnancy there is an alteration in maternal immunity within the uterus where innate, proinflammatory immune responses are tightly regulated to prevent immunological rejection of the fetal allograft. Disruption of the delicate balance of cytokines by bacteria or other factors increases the production of proinflammatory cytokines at the maternal-fetal interface and activates the parturition mechanism prematurely. Despite years of searching, there is still no broadly effective strategy for preventing preterm labor and most therapies are directed at inhibiting myometrial contractions and improving neonatal outcome. Recent studies with progestins and interleukin-10 (IL-10), however, are showing promise in randomized clinical trials and animal studies. Furthermore, the identification of the Toll-like receptors as upstream mediators of inflammation may offer alternative therapeutic targets for preventing this common pregnancy complication.

Infection as a cause of preterm birth

In summary, there is little question that intrauterine and some extrauterine infections play important roles in the etiology of early, spontaneous, preterm labor and PROM. Disappointing are the mixed results from various treatment attempts, usually with antibiotics, to reduce the preterm birth rate. Clearly, a better understanding of the pathways leading from infection to preterm birth will be necessary to develop effective interventions to reduce infection-related preterm delivery. Research must also address the question of individual susceptibility to infections and the influence of other exposures that may moderate the association between infection and preterm birth.

Anthrax during pregnancy: case reports and review

We review, in detail, 2 cases of anthrax during pregnancy, its maternal and perinatal complications, and its management. Patient 1 was a 33-year-old woman at 32 weeks of gestation. She had a submandibular eschar; extensive edema on her face, neck, and upper thorax that inhibited respiratory function; and fever. The patient was treated with penicillin G and prednisolone after the diagnosis of anthrax. She recovered within 10 days but delivered a preterm baby. Patient 2 was a 29-year-old woman at 33 weeks of gestation. Her anthrax lesion was on her right elbow, and therapy consisted of procaine penicillin. She also delivered a preterm baby. These 2 cases show that anthrax during pregnancy can be successfully managed, but preterm delivery could be a complication.

Pro-inflammatory maternal cytokine profile in preterm delivery

PROBLEM

The objective of this study was to determine the levels of cytokines produced by maternal peripheral blood mononuclear cells (PBMC) upon stimulation with a mitogen, with autologous placental cells and with a trophoblast antigen extract.

METHOD OF STUDY

Peripheral blood mononuclear cells from 54 women with a history of successful pregnancy and 30 women undergoing preterm delivery (PTD) were stimulated with the mitogen and antigens, and the cytokine levels in mitogen-stimulated culture supernatants assessed.

RESULTS

Significantly higher levels of the type 1 cytokines, interferon (IFN)-gamma and interleukin (IL)-2, were produced by the PTD group than by the normal pregnancy group, which on the contrary showed significantly greater production of the type 2 cytokines, IL-4, IL-5 and IL-10. A comparison of the ratios of type 2 to type 1 cytokines is indicative of a type 1 cytokine bias in PTD.

CONCLUSIONS

These data are suggestive of a maternal type 1 cytokine bias in PTD.

Interleukin-1beta induces calcium transients and enhances basal and store operated calcium entry in human myometrial smooth muscle

We have previously reported increased protein expression of sarcoplasmic reticulum calcium ATPase (SERCA) 2b in myometrium from women in labor at term, but the stimulus for this change is unknown. Proinflammatory cytokines have been implicated in the cascade of events leading to preterm and term labor, and we hypothesize that interleukin (IL)-1beta may induce changes in key calcium homeostatic mechanisms and, in turn, augment myometrial contractility before labor. The aim of the present study was to investigate the long-term effects of IL-1beta on SERCA 2b protein expression, calcium mobilization from intracellular stores, and store-operated calcium entry. Myometrial biopsies were obtained, with consent, from women undergoing elective cesarean section at term. Primary-cultured human myometrial smooth muscle (HMSM) cells were exposed to IL-1beta (10 ng/ml) for 24 h or to culture medium alone (control). Cells were subsequently used in Western blot studies or loaded with fura-2 to assess calcium dynamics using fluorescent digital imaging. The present study clearly demonstrated that IL-1beta significantly increased SERCA 2b protein expression in HMSM cells. Cyclopiazonic acid-induced calcium transients were also augmented, predominantly by activation of lanthanum-sensitive, store-operated calcium entry. HMSM cell excitability was enhanced, as evidenced by increased basal calcium entry and the initiation of spontaneous calcium transients in 37% of IL-1beta-treated cells. IL-1beta modulation of calcium mobilization may be an important mechanism in the cascade of events preparing the pregnant uterus for labor.

Tumor necrosis factor alpha stimulates adenylyl cyclase activity in human myometrial cells

Cytokines such as tumor necrosis factor alpha (TNFalpha) have been implicated in amniotic fluid infections and preterm and term labor. The underlying mechanisms are incompletely understood. In some smooth muscle cells, TNFalpha affects function of the beta-adrenergic/adenylyl cyclase pathway. The present study was performed to examine the effects of chronic TNFalpha exposure on adenylyl cyclase activity in cell cultures of human myometrium. Chronic TNFalpha exposure led to a dose- and time-dependent increase in basal-, GTP-, NaF-, and forskolin-stimulated adenylyl cyclase (AC) activity. The increase in AC activity was not mediated by changes in the expression of the heterotrimeric G proteins G(s)alpha or G(i)alpha as determined by immunoblotting. In addition, increases in AC activity occurred in the presence of indomethacin, indicating that these changes were not provoked by TNFalpha-induced changes in prostaglandin production. The present results suggest that TNFalpha-induced increases in AC activity in human myometrial cells obtained from the lower uterine segment occur at the level of G-protein/AC interaction or at the level of the AC enzyme itself.

Cytokines of the placenta and extra-placental membranes: roles and regulation during human pregnancy and parturition

Summary In an earlier, companion, review, we concluded that cytokines produced by the placenta and associated membranes are likely to be involved in control of the processes of implantation and placental development (Bowen et al., 2002). In this review, we discuss evidence that cytokines continue to be part of a paracrine/autocrine regulatory network in the placenta and membranes throughout the mid and late stages of gestation. Cytokines are involved in regulation of placental growth during these later stages of pregnancy and also function to protect the fetus from pathological organisms. The evidence, while not entirely consistent, suggests that production of certain cytokines within the extraplacental membranes is altered during normal term parturition, whereas in the villous placenta evidence of labour-associated changes is much more equivocal. Roles for cytokines have been postulated in many facets of parturition, including expulsion of the fetus by uterine contractions, membrane rupture, and dilation of the cervix. Imbalances and disruptions to the cytokine milieu have been implicated in a number of diseases of pregnancy involving abnormalities of both placental growth/establishment and initiation of parturition. Cytokine secretion induced by intrauterine infection is associated with increased occurrence or severity of some neonatal diseases. This wealth of data supports the view that cytokines are an integral part of a functional regulatory/communication network operating within the placental-maternal unit during normal gestation.

Intra-amniotic infection in patients with preterm prelabor rupture of membranes. Pathophysiology, detection, and management

The recent increase in knowledge about infection and preterm delivery has engendered many new questions and should make us rethink our long held beliefs and management strategies. Although this article focused primarily on infection as an important factor in the pathogenesis of PPROM, multiple other causes do exist. The various serologic and amniotic fluid assays that can identify activation of the host immune and inflammatory responses as a consequence of the microbial invasion of the amniotic cavity detailed in the preceding paragraphs are very promising but not yet available for clinical use. These tests identify the fetus in the early stages of an infectious process, before the full clinical manifestations of chorioamnionitis. Should such fetuses be treated with antibiotics in an effort to sterilize the amniotic cavity? Should patients with documented microbial invasion be delivered immediately or is there room for a more conservative management with aggressive antibiotic in utero treatment, altering the natural course of PPROM, avoiding extremely preterm deliveries? Certainly many questions remain unanswered. Continuing the search for information on the relationship between infection and PPROM can only add hope to one day finding an option for prevention, because many and probably most cases of PPROM are apparently caused by infection, and the opportunity for preventing this problem most probably lies here.

Transcriptional regulation of oxytocin receptor by interleukin-1beta and interleukin-6

The up-regulation of oxytocin (OT) receptors in late pregnancy results principally from increased synthesis of messenger RNA. The 5'-flanking region of the human OT receptor gene contains several putative binding sites for nuclear factor-interleukin-6 (NF-IL6), also known as CAAT/enhancer binding protein-beta. This trans-acting factor modulates the expression of genes involved in acute inflammatory responses. Proinflammatory cytokines, such as IL-1beta or IL-6, have been implicated as mediators in both preterm and term labor, particularly in association with intrauterine infection. We hypothesized that IL-1beta and IL-6 induce OT receptor gene expression in human myometrial cells, and this is mediated by NF-IL6 and cognate response elements in the 5'-flanking region of the OT receptor gene. Contrary to the hypothesis, both IL-1beta and IL-6 treatment resulted in a significant decrease in OT receptor messenger RNA measured by ribonuclease protection analysis. Using electrophoretic mobility shift assay, we have shown that NF-IL6 is present at low levels that appear to be increased after treatment with either IL-1beta or IL-6. Using deletion analysis and functional transfection studies in HeLa cells, we demonstrated that the OT receptor gene promoter displays constitutive basal activity and is negatively regulated by both IL-1beta and IL-6. This suppressive ability of IL-1beta and IL-6 depends on the -1203/-722 region of the OT receptor promoter, which contains binding sites for NF-IL6, acute phase response element, and NF-kappaB. Our findings suggest a role for IL-1beta and IL-6 in the transcriptional regulation of the human OT receptor gene.

Localization and regulation of IL-1alpha in rat myometrium during late pregnancy and the postpartum period

Interleukin-1 (IL-1) has been implicated as a participant in preterm labor that is induced by bacterial infection. Previously, we showed that serotonin-induced production of IL-1alpha by myometrial smooth muscle cells in vitro is also essential for the synthesis of interstitial collagenase. It is therefore likely that IL-1alpha production in uterine tissues has implications for both the normal physiology of involution and for the pathophysiological mechanisms of preterm labor. The objective of this study was to characterize the serotonin-induced production of IL-1alpha by myometrial cultures in vitro and to assess the production of IL-1alpha and its relationship to collagenase production in vivo during pregnancy and the postpartum period. Immunohistochemistry demonstrated IL-1alpha protein in the nuclei and cytoplasm of serotonin-treated myometrial cells. IL-1alpha levels were decreased by treatment with progesterone or IL-1-receptor antagonist but were unaffected by lipopolysaccharide. Western analysis of myometrium from pregnant rats showed low levels of IL-1alpha during midpregnancy with increased concentrations at days 21 and 22 and postpartum. IL-1alpha mRNA levels also increased from days 15 to 22. Levels of mRNA for IL-1beta also increased, although to a lesser degree than IL-1alpha. Both mRNAs decreased postpartum. Conversely, mRNA for interstitial collagenase was barely detectable at term but increased postpartum. Together, these data show that serotonin stimulates IL-1alpha production in vitro and indicate that normal myometrium from pregnant rats is an identifiable source of IL-1 during late pregnancy. The findings are consistent with the possibility that myometrial IL-1alpha participates in normal labor as well as the postpartum production of interstitial collagenase.

Maternal serum interleukin 6 levels in preterm labor: prediction of admission-to-delivery interval

OBJECTIVE

To evaluate the diagnostic value of maternal serum interleukin 6 (IL-6), C-reactive protein (CRP) levels and white blood cell (WBC) count for the prediction of preterm labor and length of admission-to-delivery interval in patients with preterm labor.

METHODS

Maternal serum IL-6, CRP and WBC count were prospectively determined in eighty-two patients in preterm labor and 21 controls. Data was analyzed in study and control groups, and for the assessment of clinical and laboratory risk factors in the prediction of admission-to-delivery interval in the study group.

RESULTS

Maternal serum IL-6 levels were significantly higher in the study group than controls. The IL-6 value associated with the highest percent of true positives and true negatives for the prediction of preterm labor was 5 pg/ml. The area under curve of maternal IL-6 was significantly higher than the area under curve of of CRP and WBC count. In the study group maternal serum IL-6 levels were significantly higher in patients delivered within 2 and 7 days than the nondelivering ones and a cut off value of 8.3 pg/ml was determined for estimation of preterm delivery.

CONCLUSION

Maternal serum IL-6 is a reliable marker in the prediction and management of preterm labor and delivery.

Cytokines and placental macrophages in regulation of birth activity

The article reviews present notions on functional activity of cytokines of the fetoplacental complex. Particular emphasis is placed on the role of these molecules in the regulation of gestation processes and in pregnancy incompetence. The mechanism of the involvement of placental macrophages and their products in gestation and delivery is discussed.

Current concepts on the pathogenesis and markers of preterm births

Preterm births remain a major cause of neonatal morbidity and mortality despite our efforts over the past several decades. Our improved understanding of the complex mechanisms surrounding preterm labor, however, has resulted in the development of numerous biologic and clinical predictors of spontaneous preterm births. These developments offer the exciting prospect for the creation of specific interventions that are directed toward the various pathways involved with preterm births.

Progesterone exposure prevents matrix metalloproteinase-3 (MMP-3) stimulation by interleukin-1alpha in human endometrial stromal cells

Suppression of endometrial matrix metalloproteinases (MMPs) is necessary to maintain tissue stability during the invasive events of implantation and placental development. Several laboratories have shown that inflammatory cytokines, including interleukin-lalpha (IL-1alpha), can oppose progesterone suppression of MMPs in the human endometrium. Furthermore, we have recently demonstrated colocalization of epithelial cell IL-1alpha and MMP-7 expression at sites of ectopic pregnancy. The current study extends these findings, revealing a previously unrecognized interrelationship between progesterone and IL-1alpha in regulation of MMP-3. Although IL-1alpha is a potent stimulator of MMP-3 in proliferative phase endometrium in organ culture, we demonstrate that progesterone exposure in vivo reduces IL-1alpha stimulation of MMP-3 in secretory phase tissue. This loss of sensitivity to IL-1alpha was duplicated in isolated stromal cells treated with progesterone in vitro, and IL-1alpha stimulation of MMP-3 returned in a dose-dependent manner with progesterone withdrawal. The antiprogestin, onapristone, partially blocked the ability of progesterone to prevent stimulation of MMP-3 by IL-1alpha. These data suggest a novel mechanism by which progesterone may preserve tissue integrity during the establishment and maintenance of pregnancy by limiting stimulation of MMPs by inflammatory cytokines such as IL-1a.

Induction of cyclooxygenase-2 expression in human myometrial smooth muscle cells by interleukin-1beta: involvement of p38 mitogen-activated protein kinase

1. Human myometrial smooth muscle cells (HMSMCs) in culture were exposed to recombinant human interleukin-1beta (IL-1beta, 10 ng ml-1) for 1 to 24 h. Cyclooxygenase-2 (COX-2) mRNA and protein were rapidly induced, with expression sustained at 24 h. 2. Cycloheximide (10 microg ml-1, 6 h) blocked IL-1beta-induced COX-2 protein expression and super-induced COX-2 mRNA expression. Induction of COX-2 mRNA and protein was blocked by dexamethasone (1 microm, 6 h). 3. IL-1beta-induced COX-2 expression was accompanied by a 3-fold increase of prostaglandin E2 release into the culture medium. 4. IL-1beta induced a transient (5-30 min) activation of p42/44 and p38 mitogen-activated protein kinase (MAPK) enzymes in HMSMCs. Activity of p38 MAPK was monitored by in-gel activity of its substrate MAP kinase-activated protein kinase-2 (MAPKAP kinase-2). Induction of MAPKAP kinase-2 activity was prevented by the p38 MAPK inhibitor SB 203580 (10 microm, 5-30 min). 5. COX-2 protein expression detected after 6 h IL-1beta stimulation was blocked by SB 203580 (10 microM). Exposure of HMSMCs to 10 ng ml-1 IL-1beta for only 30 min induced a level of COX-2 protein expression at 6 h culture similar to that detected in cells exposed to the cytokine for 6 h. 6. Exposure of cells to SB 203580 (10 microM during only the first 30 min of IL-1beta stimulation was effective in blocking COX-2 protein expression assayed after 6 h in culture. 7. This study has established that a transient activation of the p38 MAPK cascade is involved in IL-1beta-stimulated COX-2 expression in human myometrial smooth muscle cells. Induction of COX-2 by IL-1beta in HMSMCs provides support for the hypothesis that autocrine prostaglandin signalling in the myometrium, initiated by elevated intrauterine cytokine concentrations, plays a role in regulating myometrial contractility during labour.