Non-infected preterm parturition is related to increased concentrations of IL-6, IL-8 and MCP-1 in human cervix

Physiologic uterine inflammation and labor onset: integration of endocrine and mechanical signals

The mechanisms underlying the preparation of the uterus for labor are not fully understood. Our previous studies have shown that during pregnancy, the uterine muscle (myometrium) undergoes dramatic phenotypic modulation culminating in term labor. The current review will discuss the cellular mechanisms involved in the regulation of myometrial activity and its modulation by endocrine signals and by mechanical stimulation of the uterus by the growing fetus. In particular, the contribution of uterine inflammation to the onset of labor will be described. We provide evidence that increased production of cytokines/chemokines in pregnant myometrium is associated with uterine occupancy and regulated by progesterone, suggesting the integration of mechanical and endocrine signals. Myometrial cells can actively participate in the inflammatory process in the uterus through the release of multiple proinflammatory cytokines and chemokines, providing a strong signal for activation of immune cells, their subsequent infiltration into pregnant uterus, and the initiation of labor.

Amniotic fluid inflammatory score is associated with pregnancy outcome in patients with mid trimester short cervix

OBJECTIVE

We propose a novel amniotic fluid inflammatory score from a comprehensive cytokine analysis of patients with mid-trimester short cervix.

STUDY DESIGN

Amniotic fluid from singleton gestations (n = 44) with a cervical length of ≤25 mm between 16-24 weeks was assayed for 25 inflammatory mediators. Patient data were stratified according to gestational age at delivery (<34 vs ≥34 weeks). Mediators that reached statistical significance were included in the amniotic fluid inflammatory score. Patients were assigned 1 point for each significant mediator if their level was in the upper quartile. The amniotic fluid inflammatory score was determined, and its relationship to other clinical characteristics was examined.

RESULTS

Fourteen mediators met the criteria. A score of ≥8 was predictive of delivery at <34 weeks' gestation (sensitivity, 87.0%; specificity, 100%; positive predictive value, 100%; negative predictive value, 87.5%). Twenty patients had a high inflammatory score (≥8); 24 patients had a low score. All patients with a high inflammatory score delivered at <30 weeks' gestation.

CONCLUSION

The amniotic fluid inflammatory score is related to delivery outcome and clinical characteristics.

Preterm Cervical Ripening in humans

Preterm birth (PTB) is the leading cause of neonatal mortality and morbidity. Despite the current treatment procedures, the incidence of PTB has not changed in the past thirty years. Incomplete understanding of the biological and patophysiological mechanisms underlying preterm delivery is the major obstacle to prevent PTB. Cervical ripening is necessary for vaginal delivery and understanding of preterm cervical ripening is required for developing new treatment strategies. Several important substances such as HMGB1 and its receptors, CRH and its receptors and numerous cytokines are localized in the cervix and undergo distinct changes in labour. Other important -molecules, such as CRH, CRH-BP, CRH-R1, CRH-R2, HMGB1, TLR2, TLR4, IL-10, IL-12, are localized in the cervical epithelium, also indicating their role in the process of cervical ripening during labour. Furthermore, CRH stimulates IL-8 secretion from both preterm and term cervical fibroblasts. Recent studies from our group show that major -inflammatory changes occur in the cervix at labour irrespective of gestational age. This indicates that cervical ripening at both term and preterm is an inflammatory process even if no infection is present. However, preterm cervical ripening still entails some differences from term cervical ripening, for example in the down-regulation of mRNA expression of Toll-like receptors (TLR-2 and TLR-4) and IL-12, higher levels of IL-10 in cervical epithelium, and presents different secretion patterns of cervical fibroblasts. Moreover, preterm cervical ripening, like preterm delivery itself, is a multifactorial disorder with pathways which are partly different from those involved in PPROM and infected preterm labour.

Progesterone interactions with the cervix: translational implications for term and preterm birth

The uterine cervix plays a vital role in maintaining pregnancy and an equally important role in allowing parturition to occur. Progesterone, either endogenously produced or supplied exogenously, supports the function of the cervix in sustaining intrauterine pregnancy, and the withdrawal of progesterone, either through natural processes or pharmacologic intervention, leads to delivery which underscores the importance of the progesterone's biological activities manifest in normal gestation and pregnancy that ends prematurely. Research crossing many scientific disciplines has demonstrated that progesterone is a pleotropic compound that affects the cervix through cytoplasmic and membrane receptors with profound effects on cellular and molecular functions that influence inflammatory cascades and extracellular matrix, both of which have consequences for parturition. Beyond the local cell and molecular biology of progesterone, it has systemic effects of relevance to pregnancy as well. This paper examines the biology of the cervix from its gross to cellular structure and biological activities of its cell and molecular processes that may be affected by progesterone. The implications of these processes for preterm birth are explored, and direction of current research is in relation to translational medicine implications for diagnostic, prognostic, and therapeutic approaches to threatened preterm birth.

Roles of reactive oxygen species in female reproduction

Reactive oxygen species (ROS) are highly reactive oxidizing agents. Cells, under aerobic conditions, have a defence system against ROS, and in normal circumstances, there is an appropriate balance between pro-oxidants and antioxidants. When an overproduction of ROS develops or the body fails to eliminate ROS in excess, oxidative stress arises, during which ROS accumulate and damage cells and tissues. Besides their noxious effects, accumulating data have shown that controlled and adequate ROS concentrations exert physiologic functions. Different studies have confirmed the presence of ROS and the transcripts of the various antioxidant enzymes in the female reproductive tract. When ROS production overwhelms antioxidant defences, oxidative stress occurs, which may deeply threaten the anatomical and functional integrity of the genital tract. This review addresses the main physiological and pathological roles exerted by ROS and their scavenging systems in several processes involved in the main physiological functions of the female reproductive tract of both women and domestic animals. Particularly, the involvement of the oxidant system in several reproductive processes is investigated, such as follicular development, ovarian steroidogenesis, ovulation, corpus luteum formation and function, luteolysis, germ cell function, maintenance of pregnancy and beginning of parturition.

Negative emotions and cytokines in maternal and cord serum at preterm birth

PROBLEM

This study investigates whether affectivity differs between mothers delivering preterm and term and whether maternal and umbilical cord serum cytokines differ between these groups. Further, whether there are associations between mothers' emotions and maternal and cord cytokines at preterm and term birth.

METHOD OF STUDY

Twenty-seven mothers delivering preterm and 37 mothers delivering at term reported positive/negative affect and previous depressive symptoms during pregnancy. Blood samples from mothers in labor and cord samples (23 preterm and 33 term) were analyzed for cytokines.

RESULTS

Maternal IL-8 was lower at preterm delivery compared with term. In the preterm group only, associations were found between negative emotions and maternal IL-6, IL-8 and cord IL-6, IL-8, IL-10, IL-13, and IL-18.

CONCLUSION

The findings indicate associations in preterm delivery between negative emotions and both maternal and neonate immune activity. Future studies should investigate whether such associations are part of the etiology of preterm delivery.

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

Preterm delivery (PTD) has been associated with inflammation along with activation of the coagulation pathway. These studies sought to characterize the expression of several coagulation pathway genes including plasminogen activator inhibitor 1 (PAI-1), tissue factor (TF), protease-activated receptor 1 (Par1), protease-activated receptor 2 (Par2), fibrinogen-like protein 2 (Fgl2), and thrombomodulin (TM) during lipopolysaccharide (LPS)-induced PTD in day 15 pregnant CD-1 mice. Western blot studies confirmed protein expression for PAI-1, Par1, Par2, Fgl2, and TM in the mouse uterus. Quantitative reverse transcriptase polymerase chain reaction (RT-PCR) confirmed increased PAI-1 messenger RNA (mRNA) in the uteri, lung, kidney, and liver tissues at 2 to 6 hours after LPS injection. In contrast, TF expression significantly decreased by 12 hours in uterine tissue; whereas, its expression was unchanged in the other maternal tissues. The uterine mRNA for Par1, Par2, Fgl2, and TM remained stable. In summary, these studies have confirmed expression of coagulation pathway genes within the pregnant uterus; some of which are modulated during LPS-induced PTD.

Haemostatic and cytokine changes in gestational diabetes mellitus

BACKGROUND

Limited data indicate the existence of a hypercoagulable state and the possible involvement of pro-inflammatory cytokines in the pathogenesis of gestational diabetes mellitus (GDM).

AIM

To characterise the coagulation inhibitor and cytokine profiles in women with GDM.

METHODS

Two groups of women in the third trimester of pregnancy were studied: GDM (n = 150) and controls: women with normal pregnancy (n = 100); GDM in their first post-delivery day (n = 52). LABORATORY ASSAYS: Plasma fibrinogen, antithrombin (AT), protein C, total and free protein S, interleukins-2, 6 and 8 (IL-2, 6, 8).

RESULTS

During pregnancy, the only significant alterations noted were higher levels of body mass index, fibrinogen and total protein S in women with GDM when compared to normal pregnancy. In the post-delivery group, there was further elevation in the levels of plasma fibrinogen and significant drop in the level of total protein S, protein C and AT. Significant elevation of IL-2 and IL-6 levels was recorded only in post-delivery group.

CONCLUSION

In GDM, the only indicator of a tendency towards hypercoagulability is the higher fibrinogen levels as compared to normal pregnancy. This feature along with the higher body mass index and presumed associated insulin resistance suggests that GDM may be a mild form of the metabolic syndrome. The lack of significant change in the levels of pro-inflammatory cytokines do not support the existence of an inflammatory state in GDM.

Betamethasone effects on the endocervical inflammatory cytokines in preterm labor: a randomized clinical trial

OBJECTIVE

This study aimed to investigate the effect of betamethasone treatment on the endocervical concentration of IL-1β, IL-4, IL-6, and TNF-α in preterm labor patients.

STUDY DESIGN

We studied 68 prime-gravid women in preterm labor between 34 and 37 weeks of gestation without clinical infection. Endocervical concentrations of inflammatory cytokines were assessed; immediately on admission and 48 h after administration of two doses of intramuscular betamethasone (12 mg/kg). Wilcoxon and Mann-Whitney tests along with χ(2) and Student's t tests were utilized for statistical analysis.

RESULTS

In the betamethasone group IL-1β and TNF-α significantly decreased (P<0.001), and IL-6 and IL-4 increased (P: NS). Among patients delivered before or on the 7th day of admission IL-6 and TNF-α were higher at the most significant levels (P<0.001) compared to IL-1β and IL-4 (P: 0.001, 0.002 in respect).

CONCLUSION

Betamethasone can help induce the down regulation of endocervical inflammatory cytokines in patients with preterm labor.

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

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

Systemic inflammatory responses in progressing periodontitis during pregnancy in a baboon model

This study tested the hypothesis that pregnant female baboons exhibit increased levels of various inflammatory mediators in serum resulting from ligature-induced periodontitis, and that these profiles would relate to periodontal disease severity/extent in the animals. The animals were sampled at baseline (B), mid-pregnancy (MP; two quadrants ligated) and at delivery (D; four quadrants ligated). All baboons developed increased plaque, gingival inflammation and bleeding, pocket depths and attachment loss following placement of the ligatures. By MP, both prostaglandin E(2) (PGE(2)) and bactericidal permeability inducing factor (BPI) were greater than baseline, while increased levels of interleukin (IL)-6 occurred in the experimental animals by the time of delivery. IL-8, MCP-1 and LBP all decreased from baseline through the ligation phase of the study. Stratification of the animals by baseline clinical presentation demonstrated that PGE(2), LBP, IL-8 and MCP-1 levels were altered throughout the ligation interval, irrespective of baseline clinical values. IL-6, IL-8 and LBP were significantly lower in the subset of animals that demonstrated the least clinical response to ligation, indicative of progressing periodontal disease. PGE(2), macrophage chemotactic protein (MCP)-1, regulated upon activation, normal T cell expressed and secreted (RANTES) and LBP were decreased in the most diseased subset of animals at delivery. Systemic antibody responses to Fusobacterium nucleatum, Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans and Campylobacter rectus were associated most frequently with variations in inflammatory mediator levels. These results provide a profile of systemic inflammatory mediators during ligature-induced periodontitis in pregnant baboons. The relationship of the oral clinical parameters to systemic inflammatory responses is consistent with a contribution to adverse pregnancy outcomes in a subset of the animals.

Evidence for activation of Toll-like receptor and receptor for advanced glycation end products in preterm birth

OBJECTIVE

Individuals with inflammation have a myriad of pregnancy aberrations including increasing their preterm birth risk. Toll-like receptors (TLRs) and receptor for advanced glycation end products (RAGE) and their ligands were all found to play a key role in inflammation. In the present study, we reviewed TLR and RAGE expression, their ligands, and signaling in preterm birth.

RESEARCH DESIGN AND METHODS

A systematic search was performed in the electronic databases PubMed and ScienceDirect up to July 2010, combining the keywords "preterm birth," "TLR", "RAGE", "danger signal", "alarmin", "genomewide," "microarray," and "proteomics" with specific expression profiles of genes and proteins.

RESULTS

This paper provides data on TLR and RAGE levels and critical downstream signaling events including NF-kappaB-dependent proinflammatory cytokine expression in preterm birth. About half of the genes and proteins specifically present in preterm birth have the properties of endogenous ligands "alarmin" for receptor activation. The interactions between the TLR-mediated acute inflammation and RAGE-mediated chronic inflammation have clear implications for preterm birth via the TLR and RAGE system, which may be acting collectively.

CONCLUSIONS

TLR and RAGE expression and their ligands, signaling, and functional activation are increased in preterm birth and may contribute to the proinflammatory state.

The molecular basis for sonographic cervical shortening at term: identification of differentially expressed genes and the epithelial-mesenchymal transition as a function of cervical length

OBJECTIVE

The purpose of this study was to determine whether cervical shortening of a ripe cervix at term is associated with changes in the cervical transcriptome.

STUDY DESIGN

Sonographically measured cervical lengths and biopsy specimens were obtained from 19 women at term who were not in labor with a ripe cervix. Affymetrix HG-U133 Plus 2.0 arrays (Affymetrix Inc, Santa Clara, CA) were used. Gene expression was analyzed as a function of cervical length. Gene Ontology, pathway analyses, quantitative real-time reverse transcription-polymerase chain reaction, and immunohistochemistry were performed.

RESULTS

Cervical length shortening was associated with differential expression of 687 genes. Fifty-four biologic processes, 22 molecular functions, and 9 pathways were enriched. Quantitative real-time reverse transcription-polymerase chain reaction analysis confirmed differential expression of 13 genes. Bone morphogenetic protein-7, claudin-1, integrin beta-6, and endometrial progesterone-induced protein messenger RNA, and protein expressions were down-regulated with cervical shortening.

CONCLUSION

Sonographic cervical shortening in patients at term who are not in labor with a ripe cervix is associated with changes in the uterine cervix transcriptome. The epithelial-mesenchymal transition may participate in the mechanism of cervical shortening at term.

Mid-trimester cervical inflammatory milieu and sonographic cervical length

OBJECTIVE

The purpose of this study was to explore the relation between the relative balance of pro- and antiinflammatory cytokines in cervical fluid and mid-trimester cervical length.

STUDY DESIGN

In this prospective longitudinal cohort of women with a previous spontaneous preterm birth, mid-trimester cervical length ultrasound scans and cervical fluid levels were obtained serially. Multiple pro- and antiinflammatory cytokines were selected. We summed the multiples of the median for proinflammatory cytokines to generate the proinflammatory and the antiinflammatory scores. The relation between cervical length and pro-/antiinflammatory ratio was assessed by generalized estimating equations.

RESULTS

The pro-/antiinflammatory ratio had a negative linear association with cervical length (beta = -0.09; P < .001). Sixty percent of visits demonstrated greater concentrations of proinflammatory cytokines relative to antiinflammatory cytokines. This relationship did not change between first and last visits.

CONCLUSION

Among women with a previous preterm birth, shorter mid-trimester cervical length is associated with a more proinflammatory balance of cytokines in the cervical inflammatory milieu.

The transcriptome of cervical ripening in human pregnancy before the onset of labor at term: identification of novel molecular functions involved in this process

OBJECTIVE

The aim of this study was to identify changes in the cervical transcriptome in the human uterine cervix as a function of ripening before the onset of labor.

STUDY DESIGN

Human cervical tissue was obtained from women at term not in labor with ripe (n = 11) and unripe (n = 11) cervices and profiled using Affymetrix GeneChip HGU133Plus2.0 arrays. Gene expression was analyzed using a moderated t-test (False Discovery Rate 5%). Gene ontology and pathway analysis were performed. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used for confirmation of selected differentially expressed genes.

RESULTS

(1) Ninety-one genes were differentially expressed between ripe and unripe groups. (2) Cervical ripening was associated with enrichment of specific biological processes (e.g. cell adhesion, regulation of anatomical structure), pathways and 11 molecular functions (e.g. extracelluar matrix (ECM)-structural constituent, protein binding, glycosaminoglycan binding). (3) qRT-PCR confirmed that 9 of 11 tested differentially expressed genes (determined by microarray) were upregulated in a ripe cervix (e.g. MYOCD, VCAN, THBS1, COL5A1). (4) Twenty-three additional genes related to ECM metabolism and adhesion molecules were differentially regulated (by qRT-PCR) in ripe cervices.

CONCLUSION

(1) This is the first description of the changes in the human cervical transcriptome with ripening before the onset of labor. (2) Biological processes, pathways and molecular functions were identified with the use of this unbiased approach. (3) In contrast to cervical dilation after term labor, inflammation-related genes did not emerge as differentially regulated with cervical ripening. (4) Myocardin was identified as a novel gene upregulated in human cervical ripening.

Pro-inflammatory and anti-inflammatory cytokines in human preterm and term cervical ripening

Cervical ripening is necessary for successful delivery. Since cytokines are believed to be involved in this process, the aim of this study was to investigate possible changes in the mRNA and protein expression of pro-inflammatory cytokines (interleukin (IL)-1alpha, IL-1beta, IL-12, IL-18) and anti-inflammatory cytokines (IL-4, IL-10, IL-13) in the human cervix during pregnancy, term and preterm labor. Cervical biopsies were taken from 59 women: 21 at preterm labor, 24 at term labor, 10 at term not in labor and 4 from non-pregnant women. mRNA was analyzed with real-time RT-PCR and protein expression and/or secretion with immunohistochemistry and ELISA. There was an upregulation of mRNA for IL-10, IL-13, IL-1alpha and IL-1beta in the laboring groups, while mRNA for IL-12 and IL-18 was downregulated. IL-4 mRNA was detected more frequently, while IL-12 mRNA expression was lower, in the preterm labor group than in the term labor group. The protein levels of IL-4 and IL-12 were lower and IL-18 tended to be higher in the labor groups, while IL-10 protein levels were unaffected by labor. IL-4 protein levels were significantly higher in the preterm subgroup with bacterial infection than in the non-infected group. IL-10 had higher expression in squamous epithelium at preterm labor than at term. In conclusion, the major changes in pro-inflammatory and anti-inflammatory cytokine mRNA and protein expression in cervix occur during the labor process irrespective of the length of gestation. Our results indicate that dysregulation of anti-inflammatory cytokines in the human cervix could be involved in the pathogenesis of preterm labor.

MicroRNA expression profiling of the human uterine cervix after term labor and delivery

OBJECTIVE

MicroRNAs (miRNAs) are noncoding RNAs involved in posttranscriptional regulation of target genes. The objective of this study was to determine the miRNA expression profile of the human uterine cervix after spontaneous term labor (TL).

STUDY DESIGN

The miRNA expression pattern of cervical tissue was characterized using microarrays. Samples were collected at term from patients with (n = 8) and without (n = 9) TL. Moderated t tests and false discovery rate correction were applied. Results were confirmed using quantitative reverse transcriptase-polymerase chain reaction.

RESULTS

A total of 226 miRNAs were expressed in human cervical tissue. miR-223, miR-34b, and miR-34c were overexpressed in cervical tissue of patients with TL compared to those without. Quantitative reverse transcriptase-polymerase chain reaction assays confirmed these findings (miR-223 [fold change {FC} = 5.7], miR-34b [FC = 4.5], miR-34c [FC = 6.2]; P < .001).

CONCLUSION

This is the first report of miRNA expression in the human uterine cervix in pregnancy. Cervical remodeling after TL and delivery was associated with changes in miR-223, miR-34b, and miR-34c.

High-mobility group box protein 1 and its signalling receptors in human preterm and term cervix

The objective of this study was to identify possible changes in mRNA and protein expression of high-mobility group box protein 1 (HMGB1) and its suggested receptors - receptor for advanced glycation end-products (RAGE) and Toll-like receptor 2 (TLR2) and TLR4 - in human cervix during pregnancy, term and preterm labor. Cervical biopsies were taken from 58 women: 20 at preterm labor, 24 at term labor, 10 at term not in labor and 4 from non-pregnant women. Real-time RT-PCR was used to quantify mRNA expression, and immunohistochemistry and ELISA for protein analysis. HMGB1, RAGE, TLR2 and TLR4 proteins were localized and their mRNA expression was detected in the cervix. There was more extranuclear HMGB1 in the cervical epithelium and stroma in preterm and term labor compared to the term not in labor. TLR2 mRNA expression was upregulated 5-fold in term labor and 3-fold in preterm labor compared to term not in labor and non-pregnant controls. There was lower expression of TLR2 and TLR4 mRNAs in preterm labor compared to term. Lower mRNA expression of HMGB1 was found in the subgroup with preterm premature rupture of membranes than in the rest of the preterm group, where levels were significantly higher than in term labor. In conclusion, extranuclear expression of HMGB1 during labor suggests a possible role of HMGB1 during the process of cervical ripening. Changes in expression of mRNAs encoding HMGB1, TLR2 and TLR4 in preterm labor suggest differences in the mechanism of cervical ripening at preterm and term delivery.

Systemic immune responses in pregnancy and periodontitis: relationship to pregnancy outcomes in the Obstetrics and Periodontal Therapy (OPT) study

BACKGROUND

Our previous studies reported on the obstetric, periodontal, and microbiologic outcomes of women participating in the Obstetrics and Periodontal Therapy (OPT) Study. This article describes the systemic antibody responses to selected periodontal bacteria in the same patients.

METHODS

Serum samples, obtained from pregnant women at baseline (13 to 16 weeks; 6 days of gestation) and 29 to 32 weeks, were analyzed by enzyme-linked immunosorbent assay for serum immunoglobulin G (IgG) antibody to Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans), Campylobacter rectus, Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia (previously T. forsythensis), and Treponema denticola.

RESULTS

At baseline, women who delivered live preterm infants had significantly lower total serum levels of IgG antibody to the panel of periodontal pathogens (P = 0.0018), to P. gingivalis (P = 0.0013), and to F. nucleatum (P = 0.0200) than women who delivered at term. These differences were not significant at 29 to 32 weeks. Changes in IgG levels between baseline and 29 to 32 weeks were not associated with preterm birth when adjusted for treatment group, clinical center, race, or age. In addition, delivery of low birth weight infants was not associated with levels of antibody at baseline or with antibody changes during pregnancy.

CONCLUSIONS

Live preterm birth is associated with decreased levels of IgG antibody to periodontal pathogens in women with periodontitis when assessed during the second trimester. Changes in IgG antibody during pregnancy are not associated with birth outcomes.

Comprehensive amniotic fluid cytokine profile evaluation in women with a short cervix: which cytokine(s) correlates best with outcome?

OBJECTIVE

The objective of this study was to determine whether an expanded amniotic fluid cytokine profile predicts spontaneous preterm birth in patients with short cervix in the midtrimester.

STUDY DESIGN

Amniocentesis was performed on singleton gestations between 16-24 weeks with a cervical length <or=25 mm. Amniotic fluid from patients who received no surgical or hormonal treatment was assayed for 25 cytokines. Univariate analysis identified cytokine(s) that correlated with the interval between amniocentesis to delivery. Stepwise regression identified which cytokine(s) was most predictive of delivery, followed by the generation of receiver-operator characteristic curves. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated.

RESULTS

Forty-four amniotic fluid samples were analyzed. After stepwise regression, only monocyte chemotactic protein-1 remained significant and was the most predictive of early delivery. With a cutoff of 1320 pg/mL, monocyte chemotactic protein-1 had a 69% sensitivity, 83% specificity, 36% positive predictive value, and 87% negative predictive value to predict spontaneous preterm birth within 1 week of amniocentesis (P = .015).

CONCLUSION

Among 25 cytokines, monocyte chemotactic protein-1 was most predictive of spontaneous preterm birth.

Preterm and term cervical ripening in CD1 Mice (Mus musculus): similar or divergent molecular mechanisms?

Premature cervical ripening is believed to contribute to preterm birth (PTB). Preterm cervical ripening may be due to an aberrant regulation in timing of the same processes that occur at term, or may result from unique molecular mechanisms. Using mouse models of PTB, this study sought to investigate if the molecular mechanisms that govern cervical ripening were similar between preterm and term. Lipopolysaccharide (LPS) is infused into the uterine horn to create a mouse model of inflammation-induced PTB. For a noninfectious model of PTB, RU486 was administered. Both models result in delivery of pups in 8-24 h. Cervical tissues were collected from these models, as well as throughout gestation. Cervical tissues from E15 (preterm), E15 LPS (preterm inflammation), and E18.5 (term) were used for microarray analysis (n = 18). Additional experiments using gestational time course specimens were performed to confirm microarray results. Specific gene pathways were differentially expressed between the groups. Genes involved in immunity and inflammation were increased in the cervix in inflammation-induced PTB; term labor was not associated with differential expression of immune pathways. Cytokine expression was not increased in cervices during term labor, but was increased in the pospartum period. Epithelial cell differentiation pathway was significantly altered in term, but not preterm, labor. Activation of immune pathways may be sufficient for cervical ripening, but does not appear necessary. Differential expression of the epithelial cell differentiation pathway appears necessary in the process of cervical repair. Our results indicate that the molecular mechanisms governing preterm and term cervical ripening are distinctly different.

Cervix remodeling and parturition in the rat: lack of a role for hypogastric innervation

The hypogastric nerve is a major pathway innervating the uterine cervix, yet its contribution to the processes of cervical ripening and parturition is not known. The main objective of this study was to determine the effect of hypogastric nerve transection on remodeling of the cervix and timing of birth. As an initial goal, processes associated with remodeling of the peripartum cervix were studied. The cervix was obtained from time-dated pregnant rats on days 15, 19, 21, and 21.5 of pregnancy, and post partum on the day of birth (day 22). The cervix was excised, post-fixed overnight, and sections stained to evaluate collagen content and structure or processed by immunohistochemistry to identify macrophages or nerve fibers. The census of macrophages and density of nerve fibers in the cervix peaked on day 21, the day before birth, and then declined post partum. These results replicate in time course and magnitude previous studies in mice. To address the main objective, the hypogastric nerve was bilaterally transected on day 15 post-breeding; sham-operated rats served as controls. Pups were born in both groups at normal term. Transection of the hypogastric nerves did not affect remodeling of collagen or the census of macrophages or the density of nerve fibers in the cervix. These findings support the contention that enhanced innervation and immigration of immune cells are associated with remodeling of the cervix and parturition, but that a neural pathway other than the hypogastric nerve may participate in the process of cervical ripening.

Different secretion patterns of matrix metalloproteinases and IL-8 and effect of corticotropin-releasing hormone in preterm and term cervical fibroblasts

The aims of the present study were to compare the levels of mRNA and protein expression of matrix metalloproteinase (MMP)-1, -3, -8 and -9 in human cervical tissue in preterm and term labor as well as not in labor and to determine if corticotropin-releasing hormone (CRH) has an effect on MMP-1, -3 and interleukin (IL)-8 secretion in both preterm and term cervical fibroblasts. Cervical biopsies were taken from 60 women: 18 at preterm labor, 7 at preterm not in labor, 18 at term labor and 17 at term not in labor. ELISA and Immulite were used for protein and real-time RT–PCR for mRNA analysis. Cervical fibroblast cultures were incubated for 18 h with different CRH concentrations (10⁻¹³–10⁻⁶ M). The mRNA expression of MMP-1, -3 and -9 was higher in laboring groups compared with term not in labor. Protein levels of MMP-8 and -9 were higher in term in labor group compared with non-laboring groups. There were no significant differences in mRNA and protein expression between the preterm and respective term control groups. CRH significantly increased secretion of IL-8 in preterm and term cervical fibroblasts compared with controls. The secretion of IL-8 and MMP-1 was significantly higher and MMP-3 secretion lower in preterm cervical fibroblasts. In conclusion, cervical ripening at preterm seems to be a similar inflammatory process as at term with CRH involved. However, preterm and term cervical fibroblasts might have different phenotypes based on different secretion patterns of IL-8, MMP-1 and MMP-3.

CXCL6 (granulocyte chemotactic protein-2): a novel chemokine involved in the innate immune response of the amniotic cavity

PROBLEM

CXCL6 is a potent pro-inflammatory neutrophil chemoattractant and activator whose activity during pregnancy is not well-established. The purpose of this study was to determine if CXCL6 is present in amniotic fluid (AF) and if CXCL6 concentrations in AF change with labor (pre-term and term) or intra-amniotic infection/inflammation (IAI).

METHOD OF STUDY

A cross-sectional study was designed including the following groups: (1) mid-trimester (n = 65); (2) term no labor (n = 20); (3) term labor (n = 44); (4) patients with pre-term labor (PTL) with subsequent term delivery (n = 57); (5) PTL without IAI who delivered pre-term (n = 47); and (6) PTL with IAI (n = 62). AF CXCL6 concentrations were determined by ELISA.

RESULTS

CXCL6 was present in all term samples, but undetectable in 64/65 mid-trimester specimens. Patients with PTL and IAI had a significantly higher median AF CXCL6 concentration than those with PTL without IAI [228.9 pg/mL (0.0-8344.8) versus 55.7 pg/mL (0-454.4); P < 0.05] and those with PTL and term delivery [41.5 pg/mL (0-279.0); P < 0.05]. The median AF CXCL6 concentration did not change with spontaneous term labor [term no labor: 81.1 pg/mL (8.5-201.7) versus term labor: 75.2 pg/mL (6.7-378.7): P = 0.7].

CONCLUSION

(1) CXCL6 is detectable in AF and its concentration increases with gestational age; (2) IAI results in increased AF CXCL6 concentrations, suggesting that CXCL6 plays a role in the deployment of an inflammatory response; (3) In contrast to related chemokines, specifically IL-8, AF CXCL6 does not appear to be involved in spontaneous term parturition. These observations are novel, and suggest a role for CXCL6 in the innate immune response to microbial invasion of the amniotic cavity.

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

Preterm delivery is often associated with increased cytokine and chemokine production. These studies characterize the expression of the chemokine monocyte chemotactic protein-1 (MCP-1) in mice during lipopolysaccharide (LPS)-induced preterm delivery. Uterine and other tissues were harvested from CD-1 mice on gestational day 15 after intrauterine LPS injection. Quantitative real-time reverse-transcriptase polymerase chain reactions determined MCP-1 and toll-like receptor 4 (TLR4) mRNA expression during the 24 hours after LPS. MCP-1 protein expression was determined using a cytokine/chemokine protein array, enzyme-linked immunosorbant assay, and immunohistochemistry. Intrauterine LPS injection caused preterm delivery in CD-1 mice between 12 and 24 hours. Expression of MCP-1 mRNA significantly increased at 2 and 6 hours, while TLR4 expression did not significantly change over 24 hours. The MCP-1 protein levels peaked by 2 to 6 hours in maternal serum, liver, lung, kidney, and uterus. Immunohistochemistry confirmed MCP-1 in the myometrium and endometrium. These studies provide evidence suggesting that MCP-1 potentially plays an important role during the proinflammatory immune response, leading to preterm labor in the mouse.

ADRB3 adrenergic receptor is a key regulator of human myometrial apoptosis and inflammation during chorioamnionitis

The pathophysiology underlying preterm labor triggered by inflammatory conditions such as chorioamnionitis remains largely unclear. It has already been suggested that beta-3 adrenergic (ADRB3) agonists might be of interest in the pharmacological management of preterm labor. Although there is evidence implicating ADRB receptors in the control of inflammation, there are minimal data relating specifically to ADRB3. To explore the cellular consequences of chorioamnionitis and detect apoptosis, we first performed immunostaining and Western blot experiments on human myometrial samples obtained from women with confirmed chorioamnionitis. We then developed an in vitro model of chorioamnionitis by incubating the myometrial samples obtained from uncomplicated pregnancies with Escherichia coli lipopolysaccharide (LPS). We observed that chorioamnionitis was associated with a significant increase in cleaved CASP3 protein expression, as well as chromatin condensation, which were reproduced experimentally by LPS stimulation (10 microg/ml, 48 h). Lipopolysaccharide stimulation of normal human myometrium also induced CASP3 transcripts, increased the proapoptotic marker BAX, and decreased the antiapoptotic marker BCL2. Lipopolysaccharide-induced apoptosis was antagonized by neutralization of secreted tumor necrosis factor by a specific antibody. Furthermore, LPS stimulation increased medium culture levels of proinflammatory cytokines interleukin 6 (IL6) and IL8. Lipopolysaccharide-induced apoptosis and cytokine production were prevented by the new and potent ADRB3 agonist SAR150640 in a concentration-dependent manner. SAR150640 by itself did not exhibit any effect on apoptosis or cytokine production in control tissues. This study shows that chorioamnionitis is associated with apoptosis of human myometrial cells. It emphasizes the potential therapeutic interest of ADRB3 agonists in the field of preterm labor and other inflammatory conditions.

Signature pathways identified from gene expression profiles in the human uterine cervix before and after spontaneous term parturition

OBJECTIVE

This study aimed to discover "signature pathways" that characterize biologic processes, based on genes differentially expressed in the uterine cervix before and after spontaneous labor.

STUDY DESIGN

The cervical transcriptome was characterized previously from biopsy specimens taken before and after term labor. Pathway analysis was used to study the differentially expressed genes, based on 2 gene-to-pathway annotation databases (Kyoto Encyclopedia of Genes and Genomes [Kanehisa Laboratories, Kyoto University, Kyoto, Japan] and Metacore software [GeneGo, Inc, St. Joseph, MI]). Overrepresented and highly impacted pathways and connectivity nodes were identified.

RESULTS

Fifty-two pathways in the Metacore database were enriched significantly in differentially expressed genes. Three of the top 5 pathways were known to be involved in cervical remodeling. Two novel pathways were plasmin signaling and plasminogen activator urokinase signaling. The same analysis with the Kyoto Encyclopedia of Genes and Genomes database identified 4 significant pathways that the impact analysis confirmed. Multiple nodes that provide connectivity within the plasmin and plasminogen activator urokinase signaling pathways were identified.

CONCLUSION

Three strategies for pathway analysis were consistent in their identification of novel, unexpected, and expected pathways, which suggests that this approach is both valid and effective for the elucidation of biologic mechanisms that are involved in cervical dilation and remodeling.

Preterm labour. Cervical function and prematurity

The cervix maintains the fetus in situ during pregnancy and dilates during labour to allow delivery of the baby. Congenital or iatrogenically-induced structural abnormalities of the cervix are associated with an increased risk of preterm birth. The role of cervical infection is less clear. Cervical studies may be useful in the prediction of preterm delivery: both a shortened cervical length identified on transvaginal ultrasound examination and an increased level of fetal fibronectin in cervico-vaginal secretions are associated with an increased risk of preterm delivery. In singleton pregnancy, cervical cerclage reduces the risk of preterm birth by 25%. There is no evidence of a reduction in neonatal mortality or morbidity, and the beneficial effects of preterm birth reduction have to be set against the increased risk of maternal infection. Neither the American College of Obstetricians and Gynecologists (ACOG) nor the Royal College of Obstetricians and Gynaecologists (RCOG) has unequivocally endorsed cervical cerclage. Further work is required to define the role of the cervix in prediction and prevention of spontaneous preterm birth.

Diagnosis of early preterm labour

While preterm contractions occur almost as often extremely preterm as they do closer to term, birth due to spontaneous preterm labour before 27 weeks of gestation is rare, accounting for 0.05-0.7% of all births in different populations. Although the likelihood that uterine contractions before 27 weeks of gestation represent true preterm labour is low, the risk of adverse outcome in such cases is high. A correct diagnosis is important, and a useful diagnostic test should have a high sensitivity. In most reports, only 30-40% of women hospitalised for spontaneous preterm labour experience a preterm birth, suggesting a low positive predictive value of clinical diagnosis based on uterine contractions and vaginal examination. Transvaginal ultrasonographic scanning (TVUSS) of cervical length has shown a high sensitivity for preterm birth, 90-100% for preterm birth before 33-35 weeks, using a liberal cutoff at 30 mm. Assessment of cervicovaginal fetal fibronectin (FFN) levels has shown a sensitivity of about 80%. Adding FFN assessment to TVUSS might contribute insignificantly to the prediction of preterm birth. In a retrospective study of 147 women with spontaneous preterm labour and intact membranes before 27 weeks in our department, 61% of hospitalised women and 77% of women receiving tocolytic infusion therapy delivered before 32 weeks. Among 66 singleton pregnancies delivered before 32 weeks, at admission, 94% either had an effaced cervix or cervix with >/=2 cm dilation (74%), vaginal bleeding (61%) or serum C-reactive protein level >20 mg/l (40%), whereas one of these findings only was present in 18% of women who delivered at later gestations. Among 132 women with symptoms of spontaneous preterm contractions before 27 weeks not admitted for hospital care, only 2 (1.5%) delivered before 32 weeks, not significantly higher than for all other women (0.6%). Although TVUSS may be useful when the diagnosis of spontaneous preterm labour is in doubt, the main predicament in early spontaneous preterm labour may not be to predict preterm birth but to prevent it, since many women appear in advanced labour or with manifest chorioamnionitis.

The transcriptome of the uterine cervix before and after spontaneous term parturition

OBJECTIVE

This study was designed to identify genes differentially expressed in the human uterine cervix after spontaneous term labor.

STUDY DESIGN

The transcriptome of cervical tissue was characterized using Affymetrix HG-U133 plus 2 microarrays. Samples were collected from patients at term not in labor (n = 7) and after spontaneous labor (n = 9). Microarray statistical analysis included robust multiarray average, reduction of invariant probes, and permutation analysis for differential expression. Real-time quantitative reverse transcriptase-polymerase chain reaction assays of selected genes were performed on a new set of samples from term patients without labor (n = 10) and patients after spontaneous labor (n = 9).

RESULTS

(1) The cervical transcriptome of term patients without labor was dramatically different from that of patients who underwent labor; (2) unique genes (n = 1192) were differentially expressed in the cervical tissue from patients after spontaneous labor, compared with that of the term patients without labor (false discovery rate less than 0.05, absolute fold change greater than 2); (3) Gene Ontology analysis indicated that multiple "Biological Process" categories were enriched, including "response to biotic stimulus," "apoptosis," "epidermis development," and "steroid metabolism"; (4) of major interest, genes involved in neutrophil chemotaxis were dramatically up-regulated in specimens from women after spontaneous labor; (5) real-time quantitative reverse transcriptase-polymerase chain reaction confirmed the increased expression of interleukin-8, interleukin-6, and vascular endothelial growth factor in patients after spontaneous labor; and (6) Toll-like receptor-3 and Toll-like receptor-5 showed decreased gene expression in patients after spontaneous labor. This was confirmed by real-time quantitative reverse transcriptase-polymerase chain reaction.

CONCLUSION

(1) Cervical dilatation in term labor is associated with a stereotypic gene expression pattern determined by microarray, which is characterized by overexpression of genes involved in neutrophil chemotaxis, apoptosis, extracellular matrix regulation, and steroid metabolism; (2) Toll-like receptor-3 and Toll-like receptor-5 are differentially regulated during spontaneous parturition at term; and (3) this study provides an unbiased and comprehensive description of the changes in the cervical transcriptome before and after spontaneous term labor.

Corticotropin-releasing hormone, its binding protein and receptors in human cervical tissue at preterm and term labor in comparison to non-pregnant state

BACKGROUND

Preterm birth is still the leading cause of neonatal morbidity and mortality. The level of corticotropin-releasing hormone (CRH) is known to be significantly elevated in the maternal plasma at preterm birth. Although, CRH, CRH-binding protein (CRH-BP), CRH-receptor 1 (CRH-R1) and CRH-R2 have been identified both at mRNA and protein level in human placenta, deciduas, fetal membranes, endometrium and myometrium, no corresponding information is yet available on cervix. Thus, the aim of this study was to compare the levels of the mRNA species coding for CRH, CRH-BP, CRH-R1 and CRH-R2 in human cervical tissue and myometrium at preterm and term labor and not in labor as well as in the non-pregnant state, and to localize the corresponding proteins employing immunohistochemical analysis.

METHODS

Cervical, isthmic and fundal (from non-pregnant subjects only) biopsies were taken from 67 women. Subjects were divided in 5 groups: preterm labor (14), preterm not in labor (7), term labor (18), term not in labor (21) and non-pregnant (7). Real-time RT-PCR was employed for quantification of mRNA levels and the corresponding proteins were localized by immunohistochemical analysis.

RESULTS

The levels of CRH-BP, CRH-R1 and CRH-R2 mRNA in the pregnant tissues were lower than those in non-pregnant subjects. No significant differences were observed between preterm and term groups. CRH-BP and CRH-R2 mRNA and the corresponding proteins were present at lower levels in the laboring cervix than in the non-laboring cervix, irrespective of gestational age. In most of the samples, with the exception of four myometrial biopsies the level of CRH mRNA was below the limit of detection. All of these proteins could be detected and localized in the cervix and the myometrium by immunohistochemical analysis.

CONCLUSION

Expression of CRH-BP, CRH-R1 and CRH-R2 in uterine tissues is down-regulated during pregnancy. The most pronounced down-regulation of CRH-BP and CRH-R2 occurred in laboring cervix, irrespective the length of gestation. The detection of substantial expression of the CRH and its receptor proteins, as well as receptor mRNA in the cervix suggests that the cervix may be a target for CRH action. Further studies are required to elucidate the role of CRH in cervical ripening.