Elevated protease activities in human amnion and chorion correlate with preterm premature rupture of membranes

Development of a mouse model of ascending infection and preterm birth

BACKGROUND

Microbial invasion of the intraamniotic cavity and intraamniotic inflammation are factors associated with spontaneous preterm birth. Understanding the route and kinetics of infection, sites of colonization, and mechanisms of host inflammatory response is critical to reducing preterm birth risk.

OBJECTIVES

This study developed an animal model of ascending infection and preterm birth with live bacteria (E. coli) in pregnant CD-1 mice with the goal of better understanding the process of microbial invasion of the intraamniotic cavity and intraamniotic inflammation.

STUDY DESIGN

Multiple experiments were conducted in this study. To determine the dose of E. coli required to induce preterm birth, CD-1 mice were injected vaginally with four different doses of E. coli (103, 106, 1010, or 1011 colony forming units [CFU]) in 40 μL of nutrient broth or broth alone (control) on an embryonic day (E)15. Preterm birth (defined as delivery before E18.5) was monitored using live video. E. coli ascent kinetics were measured by staining the E. coli with lipophilic tracer DiD for visualization through intact tissue with an in vivo imaging system (IVIS) after inoculation. The E. coli were also directly visualized in reproductive tissues by staining the bacteria with carboxyfluorescein succinimidyl ester (CFSE) prior to administration and via immunohistochemistry (IHC) by staining tissues with anti-E. coli antibody. Each pup's amniotic fluid was cultured separately to determine the extent of microbial invasion of the intraamniotic cavity at different time points. Intraamniotic inflammation resulting from E. coli invasion was assessed with IHC for inflammatory markers (TLR-4, P-NF-κB) and neutrophil marker (Ly-6G) for chorioamnionitis at 6- and 24-h post-inoculation.

RESULTS

Vaginally administered E. coli resulted in preterm birth in a dose-dependent manner with higher doses causing earlier births. In ex vivo imaging and IHC detected uterine horns proximal to the cervix had increased E. coli compared to the distal uterine horns. E. coli were detected in the uterus, fetal membranes (FM), and placenta in a time-dependent manner with 6 hr having increased intensity of E. coli positive signals in pups near the cervix and in all pups at 24 hr. Similarly, E. coli grew from the cultures of amniotic fluid collected nearest to the cervix, but not from the more distal samples at 6 hr post-inoculation. At 24 hr, all amniotic fluid cultures regardless of distance from the cervix, were positive for E. coli. TLR-4 and P-NF-κB signals were more intense in the tissues where E. coli was present (placenta, FM and uterus), displaying a similar trend toward increased signal in proximal gestational sacs compared to distal at 6 hr. Ly-6G+ cells, used to confirm chorioamnionitis, were increased at 24 hr compared to 6 hr post-inoculation and control.

CONCLUSION

We report the development of mouse model of ascending infection and the associated inflammation of preterm birth. Clinically, these models can help to understand mechanisms of infection associated preterm birth, determine targets for intervention, or identify potential biomarkers that can predict a high-risk pregnancy status early in pregnancy.

Host-pathogen interaction in COVID-19: Pathogenesis, potential therapeutics and vaccination strategies

The current coronavirus pandemic, COVID-19, is the third outbreak of disease caused by the coronavirus family, after Severe Acute Respiratory Syndrome and Middle East Respiratory Syndrome. It is an acute infectious disease caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). This severe disease is characterised by acute respiratory distress syndrome, septic shock, metabolic acidosis, coagulation dysfunction, and multiple organ dysfunction syndromes. Currently, no drugs or vaccines exist against the disease and the only course of treatment is symptom management involving mechanical ventilation, immune suppressants, and repurposed drugs. The severe form of the disease has a relatively high mortality rate. The last six months have seen an explosion of information related to the host receptors, virus transmission, virus structure-function relationships, pathophysiology, co-morbidities, immune response, treatment and the most promising vaccines. This review takes a critically comprehensive look at various aspects of the host-pathogen interaction in COVID-19. We examine the genomic aspects of SARS-CoV-2, modulation of innate and adaptive immunity, complement-triggered microangiopathy, and host transmission modalities. We also examine its pathophysiological impact during pregnancy, in addition to emphasizing various gaps in our knowledge. The lessons learnt from various clinical trials involving repurposed drugs have been summarised. We also highlight the rationale and likely success of the most promising vaccine candidates.

Preterm prelabor rupture of the membranes: A disease of the fetal membranes

Preterm prelabor rupture of the membranes (pPROM) remains a significant obstetric problem that affects 3-4% of all pregnancies and precedes 40-50% of all preterm births. pPROM arises from complex, multifaceted pathways. In this review, we summarize some old concepts and introduce some novel theories related to pPROM pathophysiology. Specifically, we introduce the concept that pPROM is a disease of the fetal membranes where inflammation-oxidative stress axis plays a major role in producing pathways that can lead to membrane weakening through a variety of processes. In addition, we report microfractures in fetal membranes that are likely sites of tissue remodeling during gestation; however, increase in number and morphometry (width and depth) of these microfractures in pPROM membranes suggests reduced remodeling capacity of membranes. Microfractures can act as channels for amniotic fluid leak, and inflammatory cell and microbial migration. Further studies on senescence activation and microfracture formation and their role in maintaining membrane homeostasis are needed to fill the knowledge gaps in our understanding of pPROM as well as provide better screening (biomarker and imaging based) tools for predicting women at high risk for pPROM and subsequent preterm birth.

Ubiquitin-Proteasome-Collagen (CUP) Pathway in Preterm Premature Rupture of Fetal Membranes

Spontaneous preterm birth (sPTB) occurs before 37 gestational weeks, with preterm premature rupture of the membranes (PPROM) and spontaneous preterm labor (sPTL) as the predominant adverse outcomes. Previously, we identified altered expression of long non-coding RNAs (lncRNAs) and message RNAs (mRNAs) related to the ubiquitin proteasome system (UPS) in human placentas following pregnancy loss and PTB. We therefore hypothesized that similar mechanisms might underlie PPROM. In the current study, nine pairs of ubiquitin-proteasome-collagen (CUP) pathway–related mRNAs and associated lncRNAs were found to be differentially expressed in PPROM and sPTL. Pathway analysis showed that the functions of their protein products were inter-connected by ring finger protein. Twenty variants including five mutations were identified in CUP-related genes in sPTL samples. Copy number variations were found in COL19A1, COL28A1, COL5A1, and UBAP2 of sPTL samples. The results reinforced our previous findings and indicated the association of the CUP pathway with the development of sPTL and PPROM. This association was due not only to the genetic variation, but also to the epigenetic regulatory function of lncRNAs. Furthermore, the findings suggested that the loss of collagen content in PPROM could result from degradation and/or suppressed expression of collagens.

Differential Secretion of Matrix Metalloproteinase-2 and -9 After Selective Infection With Group B Streptococci in Human Fetal Membranes

OBJECTIVE

This study evaluated the secretions of zymogen and active forms of matrix metalloproteinase (MMP)-9 and MMP-2 and their specific inhibitors, TIMP-1 and TIMP-2 by fetal membranes stimulated with group B Streptoccocci (GBS).

METHODS

We used an in vitro experimental model that allowed us to estimate the individual contribution of the amnion (AM) and the choriodecidua (CHD) to the microbial insult. Membranes were obtained after delivery by elective cesarean delivery from women at 37 to 40 weeks of gestation without evidence of either active labor or intrauterine infection. Membranes were mounted in Transwell devices (Costar, New York, NY), physically separating the upper and lower chambers; 1 x 10(6) CFU of GBS was added to either AM or CHD and the secretions and gelatinolytic activity of MMP-2 and MMP-9 were measured in both compartments by enzyme-linked immunosorbent assay (ELISA) and zymography. TIMPs secretion was measured by ELISA. Both MMPs were immunolocalized in tissue sections.

RESULTS

The simultaneous stimulation at both sides was followed by increases of proMMP-9 (85.0 +/- 18.63 pg/mL) and proMMP-2 (4.10 +/- 1.90 ng/mL) in the CHD (P <.05). When only one side of the membrane was stimulated, the secretion level of proMMP-2 increased 2.3-fold and that of proMMP-9 2.5-fold in the CHD. The active forms of both enzymes did not change with any modality of stimulation. The secretion level of both TIMPs remained without significant changes. CHD and AM were positive for immunoreactive MMP-2 and MMP-9.

CONCLUSION

We propose that infection of fetal membranes with GBS is followed by active secretion of MMP and the CHD is the principal source of these mediators of extracellular matrix degradation.

The Role of Matrix Degrading Enzymes and Apoptosis in Repture of Membranes

Prematurity is the third leading cause of perinatal death, and preterm premature rupture of the membranes (pPROM) is associated with approximately 20-50% of all preterm births. The etiologic factors described for pPROM and preterm labor (PTL) are the same, although the clinical presentation (pPROM vs PTL) differs among patients. The reason for this disparity is unknown and poses a therapeutic dilemma. Several etiologic factors have been described for PTL and pPROM. PTL and pPROM are associated with overwhelming host inflammatory response. Many of these pro-inflammatory factors (inflammatory cytokine release) are common in both conditions; however, the clinical presentation differs. The objective of this review is to explain the differential expression pattern of matrix metalloproteinases (MMPs) and pro-apoptotic elements in human fetal membranes in pPROM and PTL and how they interact to present different clinical outcomes during pregnancy.

Maternal serum concentrations of s-Endoglin and IL-6 in pregnancy complicated by preterm premature membrane rupture

OBJECTIVE

This study aimed to investigate maternal serum concentrations of s-Endoglin and compare s-Endoglin with other inflammatory markers in prediction of time to delivery, in pregnancies complicated by preterm premature rupture of membranes (PPROM).

MATERIALS AND METHODS

Fifty five patients complicated by PPROM whose gestational age were between 2433 weeks and 44 matched healthy pregnant women were included in present study. Maternal concentrations of s-Endoglin concentrations were measured by an enzyme-linked immunosorbent assay (ELISA) and compared with maternal inflammatory markers including interleukin-6 (IL-6), white blood cell (WBC) count and serum C-reactive protein (CRP). The best variable for prediction of preterm birth was computed.

RESULTS

Mean s-Endoglin levels in PPROM were lower than control groups (0.24 ± 0.12 pg/ml and 0.69 ± 0.25 pg/ml, respectively, p < 0.01). Besides IL-6 (p < 0.01), WBC (p = 0.016) and CRP (p = 0.010) levels were higher in PPROM group. In PPROM group, ROC analysis results of s-Endoglin for prediction of preterm delivery <48 h, <7 days, <32 weeks were not different (p > 0.05). For predicting preterm birth before 48 h and 7 days, only IL-6 at cut off value >0.70 (pg/ml) and >0.55 (pg/ml) had area under curve (AUC); 0.871 (0.7750.965), p < 0.01, AUC; 0.925 (0.8560.993), p < 0.001, respectively.

CONCLUSION

s-Endoglin as an anti-angiogenic marker seemed to have a role in pathogenesis but results of present study showed that, unlike IL-6, it was unsatisfactory for estimating time to delivery in PPROM.

Viral Infection-Induced Differential Expression of LncRNAs Associated with Collagen in Mouse Placentas and Amniotic Sacs

PROBLEM

We have previously determined that long non-coding RNAs (lncRNAs) are differentially expressed in preterm premature rupture of membranes (PPROM) and hypothesized that the collagenolysis ubiquitin-proteasome system may be activated by infection and inflammation. However, direct evidence of the involvement of lncRNAs in transcriptional and posttranscriptional regulation of the infection-triggered alteration of collagen is lacking.

METHOD OF STUDY

A previously developed mouse model with MHV68 viral infection was assessed to determine whether viral infection may induce differential expression of lncRNAs in mouse placentas and amniotic sacs.

RESULTS

Differential expression of lncRNAs that are associated with collagen was found in HMV68 viral-infected, compared to non-infected, mouse placentas and amniotic sacs. Differential expression of messenger RNAs (mRNAs) of collagen was also documented.

CONCLUSIONS

Our data demonstrate, for the first time, that viral infection may induce the differential expression of lncRNAs that are associated with collagen. Based on this finding, we propose that lncRNA may have involved in regulating of infection-induced collagen transcription.

Effect of thrombin on human amnion mesenchymal cells, mouse fetal membranes, and preterm birth

Here, we investigated the effects of thrombin on matrix metalloproteinases (MMPs) and prostaglandin (PG) synthesis in fetal membranes. Thrombin activity was increased in human amnion from preterm deliveries. Treatment of mesenchymal, but not epithelial, cells with thrombin resulted in increased MMP-1 and MMP-9 mRNA and enzymatic activity. Thrombin also increased COX2 mRNA and PGE2 in these cells. Protease-activated receptor-1 (PAR-1) was localized to amnion mesenchymal and decidual cells. PAR-1-specific inhibitors and activating peptides indicated that thrombin-induced up-regulation of MMP-9 was mediated via PAR-1. In contrast, thrombin-induced up-regulation of MMP-1 and COX-2 was mediated through Toll-like receptor-4, possibly through thrombin-induced release of soluble fetal fibronectin. In vivo, thrombin-injected pregnant mice delivered preterm. Mmp8, Mmp9, and Mmp13, and PGE2 content was increased significantly in fetal membranes from thrombin-injected animals. These results indicate that thrombin acts through multiple mechanisms to activate MMPs and PGE2 synthesis in amnion.

Class I to III histone deacetylases differentially regulate inflammation-induced matrix metalloproteinase 9 expression in primary amnion cells

Matrix metalloproteinase (MMP) 9 plays an important role in the degradation of the extracellular matrix in fetal membranes, and pathological activation of MMP-9 can lead to preterm birth. In nongestational tissues, modulation of histone deacetylases (HDACs) regulates MMP-9 expression. The aim of this study was to determine whether class I to III HDACs regulate MMP-9 expression and activity in primary amnion cells. Class I and II HDAC regulation of MMP-9 was assessed using the general class I and II HDAC inhibitors (HDACi) trichostatin A (TSA) and suberoylanilide hydroxamic acid (SAHA), the class I HDACi MS-275, and the class II HDACi MC1568. Class III HDAC regulation of MMP-9 was assessed using the SIRT1 activators resveratrol and SRT1720 as well as SIRT1 small interfering RNA (siRNA). Primary amnion epithelial cells were incubated with 1 ng/mL interleukin (IL) 1β in the absence or presence of 0.3 μmol/L TSA, 5 μmol/L SAHA, 2.5 μmol/L MS-275, 2.5 μmol/L MC1568, 50 μmol/L resveratrol, or 10 μmol/L SRT1720 for 20 hours. We found that the class I and II HDACi TSA and SAHA and the class II HDACi MC1568 significantly decreased IL-β-induced MMP-9 gene and pro-MMP-9 expression in primary amnion cells. There was, however, no effect of the class I HDACi MS-275 on IL-β-induced MMP-9 expression. On the other hand, inhibition of class III HDAC SIRT1 using siRNA significantly augmented IL-1β-induced MMP-9, and SIRT1 activation using resveratrol and SRT1720 inhibited IL-1β-induced MMP-9 expression. In summary, class I to III HDACs differentially regulate inflammation-induced MMP-9 expression in primary amnion cells.

Effect of supracervical apposition and spontaneous labour on apoptosis and matrix metalloproteinases in human fetal membranes

Background. Apoptosis and matrix metalloproteinase (MMP-9) are capable of hydrolysing components of the extracellular matrix and weakening the fetal membranes which leads to eventual rupture, a key process of human parturition. The aim of this study was to determine the effect of supracervical apposition and spontaneous labour on apoptosis and MMP-9 in human fetal membranes at term. Methods. Fetal membranes were obtained from term non-labouring supracervical site (SCS) and compared to (i) a paired distal site (DS) or (ii) site of rupture (SOR) after spontaneous labour onset. Results. The expression of the proapoptotic markers Bax, Smac, Fas, FasL, caspase-3, and PARP, was significantly higher in the non-labouring SCS chorion compared to paired DS. Bax, Smac, FasL, caspase-3, and PARP staining was higher in the non-labouring SCS fetal membranes than that in the post-labour SOR. MMP-9 expression and activity were higher in the post-labour SOR fetal membranes compared to non-labouring SCS fetal membranes. Conclusion. Components of the apoptotic signalling pathways and MMP-9 may play a role in rupture and labour. Non-labouring SCS fetal membranes display altered morphology and altered apoptotic biochemical characteristics in preparation for labour, while the laboured SOR displays unique MMP characteristics.

Current status and prospects for development of a vaccine against Trichomonas vaginalis infections

Trichomonas vaginalis is a sexually transmitted pathogen with an annual worldwide incidence of over 276 million infections, the highest of all curable and non-viral STI. A large proportion of cases are asymptomatic and under-diagnosed with conventional diagnostic tools. Infection has important maternal and fetal health consequences and can lead to a higher probability of HIV transmission and susceptibility. Lack of affordable accurate diagnostic tests globally and metronidazole resistance hinder T. vaginalis control efforts. Based on data from current vaccination studies in animal models, a human vaccine is achievable to intervene on the substantial incidence of infection.

Proteomic analysis of preterm premature rupture of membranes in placental tissue

OBJECTION

Preterm premature rupture of membranes (PPROM) is an obstetrics complication and is the leading cause of perinatal mortality and morbidity. PPROM results in critical care emergencies, and nearly all PPROM events are spontaneous and unpredictable. In addition, changes in the proteome in placental tissue during pregnancy that lead to PPROM are not clear.

METHODS

We utilize a proteomics approach to study the molecular mechanisms behind human PPROM. A better understanding of proteome alteration could lead to the identification of better diagnostic/prognostic markers. Human placental tissue was collected in clearly differentiated cases of PPROM and in a healthy term control. Two-dimensional gel polyacrylamide electrophoresis coupled with mass spectrometry and bioinformatics analysis was utilized to identify proteins with altered expression.

RESULTS

In this study, only the most important protein differences were selected for further analysis. Most of the identified proteins were structural/cytoskeletal components of the cell or involved in the regulation of energy metabolism and oxidative stress.

CONCLUSIONS

As a result, this approach has led to the identification of several proteins involved in the underlying pathophysiological mechanisms that can further serve as novel diagnostic tools and targets for rational drug intervention.

The chorion layer of fetal membranes is prematurely destroyed in women with preterm premature rupture of the membranes

Preterm premature rupture of the membranes (PPROM) is an important etiology of preterm birth and source of significant neonatal morbidity. We propose that PPROM occurs in the setting of long-standing altered tissue remodeling, which creates a vulnerable environment for the fetal membranes and pregnancy. We tested the hypothesis that PPROM is the result of tissue remodeling in the fetal membranes, specifically the chorion, and this weakening of the chorion compromises the protection provided to the amnion. The purpose of this study was to quantify thickness and apoptosis in the choriodecidua of fetal membranes in patients with PPROM, preterm labor (PTL), preterm no labor (PTNL), and women with term labor (TERM). We conducted a retrospective evaluation of fetal membrane samples from 86 placentas. Immunohistochemistry was performed using a cytokeratin antibody, and mean chorion cellular thickness was compared between each clinical group. To evaluate chorion apoptosis, fetal membranes from patients with PPROM, PTL, and TERM were stained with the M30 antibody, and the degree of cellular apoptosis was determined. Statistical analysis was performed using analysis of variance with corrections for multiple comparisons. The chorion cellular layer was thinner in patients with PPROM compared to patients with PTNL and TERM (62, 140, and 169 µm, respectively, P < .0001), though not significantly different from PTL (95 µm, P > .05). The percentage of apoptotic cells within the chorion among the patients with PPROM was greater compared to PTL and TERM (24.2%, 13.1%, and 8.4%, respectively, P < .001). The chorion cellular layer is thinner and demonstrates increased apoptosis in PPROM compared to patients with PTL, PTNL, and TERM, suggesting differential remodeling between clinical phenotypes.

Trichomonas vaginalis vaginitis in obstetrics and gynecology practice: new concepts and controversies

Trichomonas vaginalis (TV) is the most common curable sexually transmitted infection worldwide. Annually, 7.4 million new infections are estimated in the United States, which is greater than combined new cases of Chlamydia, gonorrhea, and syphilis. Serious adverse reproductive health outcomes including pregnancy complications, pelvic inflammatory disease, and an increased risk of HIV acquisition have been linked to TV infection. There are several sensitive and specific diagnostic tests available, including a newly approved nucleic acid amplification test (NAAT) that utilizes the same instrumentation platform and clinical sample as Chlamydia and gonorrhea tests. In this article, we review TV pathogenicity, adverse reproductive health outcomes, detection, and treatment followed by clinical scenarios for which TV diagnosis may prove useful in obstetrics and gynecology practice.

Fetal fibronectin signaling induces matrix metalloproteases and cyclooxygenase-2 (COX-2) in amnion cells and preterm birth in mice

Fetal fibronectin (fFN) in cervical and vaginal secretions has been used as a predictor of preterm delivery. Here, we clarified the pathological function of fFN on cell type-specific matrix metalloproteinases (MMPs) and prostaglandin synthesis in fetal membranes. Treatment of amnion mesenchymal cells with fFN resulted in dramatic increases in MMP-1 and MMP-9 mRNA and enzymatic activity as well as COX-2 mRNA and prostaglandin E(2) synthesis, activating both NFκB and ERK1/2 signaling. Fetal FN-induced increases in MMPs and COX-2 were mediated through its extra domain A and Toll-like receptor 4 expressed in mesenchymal cells. Lipopolysaccharide and TNF-α increased the release of free FN in medium of amnion epithelial cells in culture. Finally, injection of fFN in pregnant mice resulted in preterm birth. Collectively, these results indicate that fFN is not only a marker of preterm delivery but also plays a significant role in the pathogenesis of preterm labor and premature rupture of fetal membranes.

Short fetal leukocyte telomere length and preterm prelabor rupture of the membranes

BACKGROUND

Rupture of the fetal membranes is a common harbinger of imminent labor and delivery. Telomere shortening is a surrogate for oxidative stress (OS) and senescence. Fetal leukocyte and placental membrane DNA telomere lengths were evaluated to determine their association with preterm prelabor rupture of the membranes (pPROM) or spontaneous preterm births with intact membranes (PTB), compared to term birth.

METHODS

Telomere lengths were quantified in cord blood leukocytes (n = 133) from three major groups: 1) pPROM (n = 28), 2) PTB (n = 69) and 3) uncomplicated full term births (controls, n = 35), using real-time quantitative PCR. Placental membrane specimens (n = 18) were used to correlate fetal leukocyte and placental telomere lengths. Telomere length differences among the groups were analyzed by ANOVA. Pearson correlation coefficients determined relationships between leukocyte and placental membrane telomere lengths.

RESULTS

In pregnancies with intact membranes, fetal leukocyte telomere length was inversely proportional to gestational age. The mean telomere length decreased as gestation progressed, with the shortest at term. pPROM had telomere lengths (9962 ± 3124 bp) that were significantly shorter than gestational age-matched PTB (11546 ± 4348 bp, p = 0.04), but comparable to term births (9011 ± 2497 bp, p = 0.31). Secondary analyses revealed no effects of race (African American vs. Caucasian) or intraamniotic infection on telomere length. A strong Pearson's correlation was noted between fetal leukocyte and placental membrane telomere lengths (ρ = 0.77; p<0.01).

CONCLUSIONS

Fetal leukocyte telomere length is reduced in pPROM compared to PTB but is similar to term births. pPROM represents a placental membrane disease likely mediated by OS-induced senescence.

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

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

Mechanisms of leukocyte accumulation and activation in chorioamnionitis: interleukin 1 beta and tumor necrosis factor alpha enhance colony stimulating factor 2 expression in term decidua

Chorioamnionitis is a major cause of prematurity as well as perinatal morbidity and mortality. The present study observed a marked increase in immunohistochemical staining for Colony Stimulating Factor 2 (CSF2; also known as granulocyte macrophage-colony stimulating factor), a potent neutrophil and macrophage chemoattractant and activator, in the decidua of patients with CAM compared with controls (n = 8; P = .001). To examine the regulation of this CSF2, cultured decidual cells primed with estradiol (E2) or E2 plus medroxyprogesterone acetate, were exposed to tumor necrosis factor-alpha or interleukin-1beta and secreted CSF2 measured by ELISA. Levels of CSF2 in E2 plus MPA-treated cultures increased 18- and 245-fold following treatment with TNF or IL1B (n = 7, P < .05). Quantitative RT-PCR demonstrated parallel changes in mRNA levels. This study reveals that CSF2 is strongly expressed in decidua from patients with CAM and indicates TNF or IL1B as important regulators of CAM-related decidual leukocyte infiltration and activation.

Evaluation of the expression and enzyme activity of matrix metalloproteinase-7 in fetal membranes during premature rupture of membranes at term in humans

Amnion, chorion, and decidua were separated from fetal membranes at term from women with no labor (cesarean delivery [CS], n = 10), labor (normal delivery, n = 10), and labor during premature rupture of membranes (PROM; n = 8) for evaluation of matrix metalloproteinase (MMP)-7. The expression of pro-MMP-7 was immunohistochemically demonstrated in amnion, chorion, and decidua. Interestingly, however, Western blotting revealed that pro-MMP-7 and MMP-7 expression was the lowest in amnion from PROM, whereas it was the highest in chorion and decidua from PROM. Importantly, the enzymatic activity of MMP-7 determined with an MMP-7-specific substrate was higher in amnion from PROM than that from CS. Moreover, the tissue inhibitor of metalloproteinase (TIMP)-1 level was lower in amnion from PROM than that from CS. Thus, MMP-7 is expressed in fetal membranes (amnion, chorion, and decidua), and its activity is increased in amnion of PROM at term, accompanied with the reduced level of TIMP-1, which may suggest the possible involvement of MMP-7 in PROM.

Matrix metalloproteinases-2, -3 and -9 in human term placenta

Matrix metalloproteinases (MMPs) are zinc-dependent enzymes that degrade the components of the extracellular matrix (ECM) and are known to be the main mediators of human placentation and parturition. Although there are many studies on the roles and distribution of MMPs in human term placenta, so far none of the studies has investigated the distribution of MMP-2, -3 and -9 in different cells of various placental sites. In this study, we aimed to determine the distribution and enzymatic activities of MMP-2, -3 and -9 with regard to different regions of term human placenta, such as amnion, basal plate, chorionic plate, decidua, chorion laeve, Nitabuch's stria, umbilical cord and placental villi. Eighteen normal human term placentas were obtained after vaginal deliveries. Immunohistochemistry and zymography were performed for MMP-2, -3 and -9 on placental tissue sections and protein extracts, respectively. Nearly all tissues showed immunoreactivity for MMPs. The strongest enzymatic activity for MMP-2 was seen in areas where invasive trophoblast cells invaded maternal tissues. MMP-9 had the highest enzymatic activity at the contact region of fetal and maternal parts, suggesting the importance of MMP-9 in separation of the placenta from the uterine wall during labor. MMP-3 had a similar localization to MMP-9, suggesting that besides gelatinases like MMP-2 and -9, MMP-3 (stromelysin-1) may also have important roles during labor. This study describes the site-specific distribution and activities of MMPs and therefore might help in elucidating the molecular mechanisms in pathologies such as premature rupture of membranes.

Infection and the role of inflammation in preterm premature rupture of the membranes

Spontaneous preterm birth, caused by preterm labor (contractions before 37 weeks' gestation) or preterm premature rupture of the membranes (pPROM) (membrane rupture before the onset of labor) or both account for approximately 80% of preterm deliveries. pPROM is associated with 30-40% of preterm deliveries and the incidence of pPROM has increased in the past decade. The question we address here is why some women experience pPROM and some experience preterm labor with no rupture of membranes (ROM) when the etiologic factors associated with both these pathologic complications are the same. To date, studies had evaluated the markers that are commonly elevated in both preterm labor and pPROM. A better understanding of the similarities and differences between the biomolecular pathways leading to each of these conditions may open new avenues for research and intervention. In this chapter we review the role of inflammatory mediators (cytokines and matrix metalloproteinases), and programmed cell death (apoptosis) in preterm labor with no ROM and preterm labor with pPROM to delineate the differences in pathways between the two conditions.

Changes in matrix metalloproteinase 2 activities in amniochorions during premature rupture of membranes

OBJECTIVE

Increased proteolytic activities of matrix metalloproteinases (MMPs) such as MMP-3 and MMP-9 are associated with premature rupture of membranes at term. However, it is unclear whether MMP-2 is involved in the premature rupture of membranes. In this study, to elucidate the role of MMP-2, we evaluated the activity of MMP-2 and also the expression of pro-MMP-2, membrane type 1 (MT1)-MMP and tissue inhibitor of metalloproteinase (TIMP)-1 in premature rupture of membranes.

METHODS

Amniochorions were prepared from 29 subjects with no labor (cesarean section; CS, n = 10), labor (normal delivery; ND, n = 10), and labor during premature rupture of membranes (PROM, n = 9). MMP-2 activity was spectrophotometrically assayed by measuring the digestion of an MMP-2-specific substrate. The levels of pro-MMP-2, MT1-MMP and TIMP-1 were determined by Western immunoblotting.

RESULTS

The activity of MMP-2 in PROM was significantly higher than that in CS and ND (P <.05). In addition, the levels of MT1-MMP, an activator of MMP-2, were higher in PROM than in CS and ND. In contrast, the level of TIMP-1, an inhibitor of MMP-2 was substantially lower in PROM than CS and ND. Moreover, the levels of pro-MMP-2 were increased more significantly in PROM and ND than in CS (P <.05).

CONCLUSION

Our results suggest that the increased expression of pro-MMP-2 and MT1-MMP and decreased expression of TIMP-1 may result in the increased activity of MMP-2, which is involved in the degradation of extracellular matrix (ECM) of fetal membrane, thereby inducing the premature rupture of membranes at term.

Fetal membrane healing after spontaneous and iatrogenic membrane rupture: a review of current evidence

In view of the important protective role of the fetal membranes, wound sealing, tissue regeneration, or wound healing could be life saving in cases of preterm premature rupture of the membranes. Although many investigators are studying the causes of preterm premature rupture of membranes, the emphasis has not been on the wound healing capacity of the fetal membranes. In this review, the relevant literature on the pathophysiologic condition that leads to preterm premature rupture of membranes will be summarized to emphasize a continuum of events between rupture and repair. We will present the current knowledge on fetal membrane wound healing and discuss the clinical implications of these findings. We will critically discuss recent experimental interventions in women to seal or heal the fetal membranes after preterm premature rupture of membranes.

Proteomics, Part II: The Emerging Role of Proteomics Over Genomics in Spontaneous Preterm Labor/Birth

Conventional wisdom holds that complications of immature organ systems such as respiratory distress syndrome, intraventricular hemorrhage, necrotizing enterocolitis, and bronchopulmonary dysplasia are the primary causes of the high neonatal morbidity and mortality attendant preterm delivery. However, recent evidence suggests that a major cause of prematurity-associated neonatal pathology is the fetal and neonatal response to inflammation/infection. Although functional genomics offered the promise of providing answers to many of these questions, the identification of the genes intrinsic to human parturition proved to be a difficult task. Proteomic profiling of the amniotic fluid (AF) provides a precise means for detection of inflammation by revealing the presence of 4 biomarkers (defensins-2 and -1, calgranulin-C, and calgranulin-A) that are highly predictive of intrauterine inflammation (MR score). The MR score is especially useful as it presents a gradient of disease activity progressing from "absent" to "mild" to "severe" inflammation. Thus, it provides the ability to identify patients who may benefit from interventions in utero in a modern diagnostic-therapeutic framework.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to explain that the cause or causes of preterm delivery are still unknown, recall that functional genomics has not given the answer to these causes, and state that proteomic profiling of amniotic fluid, through mass-restricted (MR) scoring, may be predictive of intrauterine inflammation and allow for potential diagnosis and potential therapy.

Salivary proteinase activity: a potential biomarker for preterm premature rupture of the membranes

OBJECTIVE

The objective of this study was to design a method to identify patients at risk for preterm premature rupture of the membranes using a simple assay of salivary proteinase activity.

STUDY DESIGN

Saliva samples were collected from women in the following groups using Salivette: (1) nonpregnant control; (2) during the second trimester of pregnancy; (3) during active labor at term; (4) women with premature rupture of the membranes before preterm delivery; and (5) postpartum (within 3 hours after delivery at term). Total proteolytic activity in saliva samples was measured by fluorometry using the generic substrate DQ-gelatin in the presence of specific inhibitors to selectively detect matrix metalloproteinase activities. The concentrations of various matrix metalloproteinases in saliva samples were also measured by multiplex bead assay using the Luminex platform.

RESULTS

All saliva samples exhibited detectable matrix metalloproteinase activity. Salivary matrix metalloproteinase activity is low in nonpregnant females (0.27 +/- 0.15) and increases in samples taken in the second trimester (0.5 +/- 0.5) and at term during active labor (1.03 +/- 1.2). Samples collected from women with premature rupture of the membranes before preterm delivery had the highest activity (2.5 +/- 3.7) followed by postpartum after normal term delivery (2.1 +/- 1.6). The matrix metalloproteinase activity was higher in premature rupture of the membranes before preterm delivery samples, compared with all other stages of pregnancy. Multiplex matrix metalloproteinase assay documented a significant increase in total matrix metalloproteinase-9 concentration in saliva from premature rupture of the membranes before preterm delivery, compared with any of the other groups. Similarly matrix metalloproteinase-9 activity was also significantly increased in premature rupture of the membranes before preterm delivery group, compared with all others.

CONCLUSION

Herein we report a simple test to monitor proteolytic enzyme activity in saliva during pregnancy. The highest matrix metalloproteinase activity is seen in premature rupture of the membranes before preterm delivery and postpartum samples. Ongoing studies aim to further define salivary proteinase activity in patients at high risk for premature rupture of the membranes before preterm delivery and to evaluate its potential as a predictive test for premature rupture of the membranes before preterm delivery.

Are vaginal fluid procalcitonin levels useful for the prediction of subclinial infection in patients with preterm premature rupture of membranes?

AIM

To compare vaginal fluid procalcitonin concentrations in cases of preterm premature rupture of membranes (pPROM) and premature rupture of membranes (PROM) at term, and to determine whether the procalcitonin concentrations are of value in the diagnosis of pPROM cases suspected of subclinical intrauterine infection or in the prediction of the pPROM-to-delivery interval.

METHODS

Forty-eight patients with pPROM and 30 with PROM at term were enrolled in this study. In pPROM group, analysis was conducted of procalcitonin concentrations with reference to serum leucocytosis, serum C-reactive protein levels and vaginal fluid culture, as well as to the presence/absence of neonatal congenital infection or histological chorioamnionitis. The outcomes of pPROM cases were also recorded with reference to pPROM-to-delivery interval.

RESULTS

Procalcitonin levels in the pPROM group were significantly higher than in cases of amniorrhexis at term (1.50 vs 0.83 ng/mL; P < 0.001). In the pPROM group procalcitonin concentrations between the patients with and without positive laboratory indices of infection were comparable. Also, no significant correlation was observed between procalcitonin and leucocytosis (r = -0.14; P = 0.33) or C-reactive protein (r = -0.17; P = 0.24). Procalcitonin concentrations of patients who gave birth to newborns with infection were comparable to those in women whose newborns were healthy. In patients with histological chorioamnionitis, procalcitonin concentrations were comparable to those without inflammatory changes.

CONCLUSION

These findings suggest that the value of vaginal fluid procalcitonin determinations is unsatisfactory in the diagnostics of pPROM cases suspected of subclinical intrauterine infection, as well as for the prediction of pPROM-to-delivery interval, newborn's congenital infection or histological chorioamnionitis.

Proinflammatory cytokines found in amniotic fluid induce collagen remodeling, apoptosis, and biophysical weakening of cultured human fetal membranes

The mechanisms by which fetal membranes (FM) rupture during the birth process are unknown. We have recently reported that FM weaken, at least in part, because of a developmental process of extracellular matrix remodeling and apoptosis. We now hypothesize that cytokines that normally increase in amniotic fluid at term induce FM collagen remodeling and apoptosis with concomitant weakening. Full-thickness FM fragments were cultured with (0-100 ng/ml) or without tumor necrosis factor (TNF) or interleukin 1, beta (IL1B). Physical properties were then examined with specially adapted industrial rupture strength testing equipment. Cultured FM were also evaluated for evidence of collagen remodeling and apoptosis. Cytokine-treated FM exhibited a dose-dependent decrease in strength and work to rupture. Compared with controls, the highest TNF dose caused maximal decrease in FM rupture strength (13.2 +/- 1.2 N versus 3.8 +/- 1.5 N; P = 0.0003) and work to rupture (0.035 +/- 0.005 J versus 0.005 +/- 0.002 J; P < 0.0001). The highest IL1B dose also decreased rupture strength (12.9 +/- 3.2 versus 4.6 +/- 1.1 N; P = 0.0027) and work to rupture (0.018 +/- 0.005 J versus 0.005 +/- 0.002 J; P < 0.01). Matrix metalloproteinase 9 (MMP9) protein increased, tissue inhibitor of matrix metalloproteinase 3 (TIMP3) protein decreased, and poly (ADP-ribose) polymerase (PARP1) cleavage increased with increasing TNF or IL1B doses (all P < 0.05), suggesting collagen remodeling and apoptosis. TNF and IL1B cause significant weakening of cultured FM. Both cytokines induce biochemical markers in the FM in a manner characteristic of the weak zone of FM overlying the cervix. TNF and or IL1B may be involved in the development of the weak zone of the FM.

Changes in matrix metalloproteinase (MMP)-2 and MMP-9 in the fetal amnion and chorion during gestation and at term and preterm labor

Increased matrix metalloproteinase (MMP)-9 proteolytic activity is associated with term birth, preterm birth and premature rupture of membranes. However, most studies show no changes with MMP-2, which binds tightly to cell and matrix proteins. We hypothesized better protein extraction would reveal new MMP patterns. Human amnion and chorion were collected from 25 patients at preterm or term, extracted with 2% SDS (a high concentration), and the MMP protein levels and pro-enzyme activities were determined by Western immunoblotting and zymography. MMP-2 protein and MMP-2 and -9 pro-enzyme activities in the amnion increased significantly (p<0.05) with labor at term, and were higher than at preterm labor (p<0.05), when extracted with high SDS concentration. There were no changes in chorion MMPs under any condition. These associations suggest MMP-2 may be another regulator of membrane rupture and other labor-associated mechanisms at term parturition, and its role(s) should be examined further.

Nanomolar and micromolar effects of 15-deoxy-delta 12,14-prostaglandin J2 on amnion-derived WISH epithelial cells: differential roles of peroxisome proliferator-activated receptors gamma and delta and nuclear factor kappa B

15-Deoxy delta(12,14)-prostaglandin J(2) (15d-PGJ(2)), an activator of peroxisome proliferator-activated receptor (PPAR)-gamma and -delta, is a prostanoid metabolite with anti-inflammatory actions. In intrauterine tissues, proinflammatory cytokines and prostaglandins have been identified as playing key roles in the maintenance of pregnancy and the onset of labor. We investigated and compared the early (<3 h) effects of 15d-PGJ(2) with rosiglitazone (PPAR-gamma ligand) and 2-methyl-4-((4-methyl-2-(4-trifluoromethylphenyl)-1,3-thiazol-5-yl)-methylsulfanyl)phenoxy-acetic acid (GW501516) (PPAR-delta ligand) on interleukin (IL)-1beta-induced prostaglandin and cytokine production by amnion-derived WISH cells. We show that 15d-PGJ(2) exerts differential effects depending on concentration. At low concentrations (<0.1 microM), 15d-PGJ(2) inhibited IL-1beta-stimulated prostaglandin E(2) (PGE(2)) but not cytokine (IL-6/IL-8) production or cyclooxygenase-2 (COX-2) expression. This effect was attenuated by a PPAR-gamma inhibitor [2-chloro-5-nitro-N-phenyl-benzamide (GW9662)], by transfection with a dominant-negative PPAR construct, and was reproduced by the PPAR-gamma ligand rosiglitazone. At higher concentrations (1-10 microM), 15d-PGJ(2) inhibited IL-1beta-stimulated PGE(2) and cytokine production and COX-2 expression, and this effect was not blocked by GW9662. Rosiglitazone at high concentrations (1-10 microM) stimulated PGE(2) production in the absence or presence of the dominant-negative PPAR. The PPAR-delta ligand GW501516 also inhibited IL-1beta-stimulated PGE(2) production but only at high concentrations (1 microM). IL-1beta-induced nuclear factor-kappaB (NF-kappaB) DNA binding activity was significantly inhibited by 15d-PGJ(2) (10 microM) and GW501516 (1 microM) but increased with 10 microM rosiglitazone. We conclude that 1) at low concentrations, 15d-PGJ(2) acts through a PPAR-gamma signaling pathway; b) at higher concentrations, its actions are mediated most likely through other pathways such as activation of PPAR-delta and/or inhibition of NF-kappaB; and 3) rosiglitazone exerts PPAR-independent effects at high concentrations (>1 microM).

Fetal membrane inflammatory cytokines: a switching mechanism between the preterm premature rupture of the membranes and preterm labor pathways

Inflammatory cytokines are involved in both preterm labor and preterm premature of the membranes pathways; however, the interaction between TNF-alpha and its receptors may dictate the clinical outcome of pregnancy.

Vitamin C Exacerbates Hydrogen Peroxide Induced Apoptosis and Concomitant PGE2Release in Amnion Epithelial and Mesenchymal Cells, and in Intact Amnion

This study was undertaken to investigate the effect of hydrogen peroxide (HP), a reactive oxygen species, and vitamin C, an antioxidant, on apoptosis and prostaglandin (PGE(2)) release in human amnion epithelial and mesenchymal cells, and intact amnion. Amnion cells and explants were incubated with and without HP and vitamin C. Cytoproliferation assay for viability, DNA fragmentation and PARP cleavage for apoptosis, EIA for PGE(2), and western blots for cyclooxygenases (COX) were performed. In amnion cells and explants, HP (0-5 mm) induced dose dependent apoptosis as per DNA fragmentation and PARP cleavage. HP (0-0.5 mm) also induced PGE(2)release concomitant with apoptosis in both cell types. In amnion explants, HP (0-10 mm) induced COX-2 protein and PGE(2)release concomitant with apoptosis. Vitamin C (0.01-10 mm), alone, enhanced epithelial but inhibited mesenchymal cell viability. It induced PGE(2)release in amnion explants. Vitamin C (1 mm) failed to inhibit HP induced apoptosis, but instead exacerbated it in epithelial and mesenchymal cells, and amnion explants. Vitamin C (0-10 mm) enhanced HP induced PGE(2)in mesenchymal cells. HP induces concomitant apoptosis and PGE(2)release in amnion epithelial and mesenchymal cells, and in intact amnion explants. HP induced apoptosis is not inhibited but enhanced by vitamin C.

Hydrogen Peroxide Induced Apoptosis in Amnion-derived WISH Cells is not Inhibited by Vitamin C1∗Presented in part at the Society for Gynecologic Investigation annual meeting in Washington, DC, 26–30 March, 2003

Increased reactive oxygen species (ROS) have been identified as a potential cause of remodelling and apoptotic change in fetal membrane. Vitamin C has been suggested as a therapeutic agent to prevent ROS induced chorio-amnion apoptosis. The purpose of this study was to determine whether hydrogen peroxide (HP), a ROS, initiates apoptosis in the WISH cell model and whether vitamin C would inhibit HP induced apoptosis. HP induced apoptosis in WISH cells; as assessed by cytochrome-c release from mitochondria, Poly-(ADP-ribose)-Polymerase (PARP) cleavage, nuclear matrix protein (NMP) release and DNA fragmentation analysis. HP induced dose dependent release of cytochrome-c, PARP cleavage, NMP release, and DNA fragmentation. HP also increased PGE(2)release in parallel with apoptosis in WISH cells, in a manner similar to that reported with other apoptotic agents. Vitamin C pre-incubation caused cytochrome-c release earlier, and at lower HP doses, than HP alone. It had no effect on HP induced PARP cleavage, but enhanced DNA fragmentation, and induced NMP release on its own. Vitamin C partially suppressed dose dependent HP induced PGE(2)release. We conclude that HP causes apoptosis in WISH cells and vitamin C pre-incubation does not inhibit, and may accelerate and exacerbate, HP induced apoptosis.

Chorioamniotic membrane separation following open fetal surgery: pregnancy outcome

OBJECTIVE

To review the incidence of posthysterotomy chorioamniotic membrane separation and delivery outcome following open fetal surgery [myelomeningocele (MMC); cystic adenomatoid malformation (CCAM); congenital diaphragmatic hernia (CDH); sacrococcygeal teratoma (SCT)].

STUDY DESIGN

Retrospective review of a maternal population undergoing open fetal surgery at a single tertiary level program (1998-2001) following the initiation of close postoperative ultrasound follow-up for membrane separation. Onset of membrane separation was coded as not present (NP), immediate (<2 weeks) or delayed (>2 weeks) from day of surgery.

RESULTS

Fifty-three charts were reviewed: MMC 43, CCAM 7, CDH 1, and SCT 2. In the MMC group there were 26 NP, 8 immediate, and 9 delayed. Preterm labor occurred in 4 patients with only 2 having had membrane separation. Risk of membrane separation is increased for surgery done at less than 23 weeks gestation (p < 0.005). Delay from MMC surgery to delivery was 11.0, 9.8, 12.0 weeks for NP, immediate, and delay, respectively. In the MMC group, there were 3 neonatal deaths (NND) at 9, 9, and 21 days post surgery (PROM/PTL; chorioamnionitis, PROM/PTL, respectively). No membrane separation was present in the CCAM, CDH, and SCT cases.

CONCLUSIONS

(1) Membrane separation was significantly more likely to occur if surgery was performed prior to 23 weeks. (2) Membrane separation post hysterotomy (17/50 = 34%) may be associated with an increased risk of PROM but not delivery before 30 weeks gestation. (3) Delivery prior to 33 weeks gestation for MMC groups was 12/43 (28%) with 3 NND (7%). (4) Elective delivery at 36-37 weeks gestation was possible for 43% of the fetal surgery population.

Cytokines, prostaglandins and parturition--a review

The elaboration of cytokines, chemokines and immunomodulatory proteins in the placenta and gestational membranes has been extensively investigated in the context of both normal and abnormal pregnancy and delivery. Patterns of expression of cytokines in the foetal membranes and decidua suggest that inflammatory activation occurs modestly with term labour, but much more robustly in preterm delivery, particularly in the presence of intrauterine infection. Enhanced chemokine expression, particularly evident in deliveries with an infected amniotic cavity, is presumably responsible for recruiting infiltrating leukocytes into the membranes thereby amplifying the inflammatory process and hastening membrane rupture and delivery. Anti-inflammatory cytokines suppress inflammatory reactions in the placenta, but under some circumstances may act in a pro-inflammatory fashion in the membranes. Intracellular signalling by cytokines is modulated by proteins such as SOCS (Silencer Of Cytokine Signalling)-1, -2 and -3. Changes in the abundance of these proteins occur with term labour, implicating them as modulators of cytokine actions around the time of parturition. Prostaglandins, released by the membranes in response to stretch and the actions of pro-inflammatory cytokines, act not only upon the myometrium and cervix, but may also exert paracrine/autocrine effects on cell viability and matrix protein integrity. The localization and regulation of prostanoid isomerases, responsible for converting PGH(2) (derived from prostaglandin H synthase-1 and -2) to bioactive prostanoids, are being studied in these tissues, particularly in the context of cytokine interactions. Although the gestational tissues are known to be sources of PGD(2), PGJ(2) and its derivatives, the regulation of production of these prostaglandins has yet to be studied in any detail and their actions, which may include apoptosis and suppression of inflammation, remain poorly defined. A more complete understanding of these aspects of cytokine-prostaglandin interactions in pregnancy and parturition will, no doubt, unfold as current studies come to fruition.

Increased levels of interleukin-6 in cervical secretions and assessment of the uterine cervix by transvaginal ultrasonography predict preterm premature rupture of the membranes

OBJECTIVE

The objective of this study was to investigate the predictive factors of premature rupture of the membranes (preterm PROM).

METHODS

The study was undertaken with cervical secretions collected from 72 consenting singleton pregnant women between 20 and 33 weeks of gestation. The levels of interleukin (IL) 1alpha, IL-1beta, IL-6, IL-8, matrix metalloproteinase (MMP) 1, MMP-2, MMP-9, tissue inhibitors of matrix metalloproteinase (TIMP) 1, TIMP-2, granulocyte elastase, and fetal fibronectin in cervical diluted specimens were measured by immunoassay, and the uterine cervix was assessed by transvaginal ultrasonography. Demographic, obstetric, clinical, neonatal, and laboratory data were analyzed by univariate analysis, multiple logistic regression, and receiver operator characteristic curve analysis.

RESULTS

Preterm PROM occurred in 6 women, and 63 women delivered at term. Multiple logistic regression analysis indicated a significant independent association with preterm PROM for the cervical IL-6 levels and cervical length. The receiver operator characteristic curve analysis revealed that an IL-6 level of >/=240 pg/ml in cervical secretions and a cervical length of </=28 mm had higher diagnostic performance in predicting preterm PROM.

CONCLUSION

It is suggested that preterm PROM is associated with increased cervical IL-6 levels and a short cervix.

Collagenase-3 (MMP-13) in fetal membranes and amniotic fluid during pregnancy

OBJECTIVE

To examine the expression, site of production and a role of collagenase-3 in human fetal membranes and amniotic fluid (AF).

METHODS

Amniochorion collected at the time of elective repeat cesareans prior to labor from normal term gestation, were placed in an organ explant system for 72 hr. The AF was collected from the following groups of women: women at term; women at third trimester pregnancy; women at mid-trimester pregnancy. Women with premature rupture of the membranes (PROM) with or without pre-term labor and infection delivered by cesareans before term; women with pre-term labor and no rupture of membranes and delivered by cesareans before term. The mRNA expression of collagenase-3 was studied by reverse transcriptase-polymerase chain reaction (RT-PCR) and protein concentrations in the AF were assayed by enzyme-linked immunosorbent assay (ELISA). Site of collagenase-3 production was documented by immunohistochemistry. Statistical comparisons were made using ANOVA. All statistical hypotheses were adjusted for multiple comparisons using the Scheffe method of adjustment.

RESULTS

Amniochorion at term expressed collagenase-3 mRNA. Immunohistochemistry localized collagenase-3 in both amnion and chorion. Collagenase-3 was seen in AF from all gestational age groups with lowest levels at mid-trimester [167.8 pg/mL] and highest during term labor (323.92 pg/mL) with no statistically significant difference between term and third trimester (310.11 pg/mL). AF levels of collagenase-3 were significantly higher in women with pre-term labor (370.02 pg/mL; P(adj) = 0.046) or pre-term labor and infection (628.73 pg/mL; P(adj) = 0.002) compared with PROM with pre-term labor and infection (87.19 pg/mL).

CONCLUSION

Collagenase-3 mRNA is constitutively expressed and produced in amniochorion. It is a normal physiologic constituent of AF. PROM is not associated with an increase in the AF collagenase-3.

Screening of novel matrix metalloproteinases (MMPs) in human fetal membranes

OBJECTIVE

Endogenous activation of matrix metalloproteinase (MMP) in human fetal membranes is hypothesized to contribute to membrane weakening leading to early rupture and is also involved in the initiation of labor. Our laboratory and several others have studied the source and action of some of these MMPs. The objective of this study is to document the expression pattern of most of the MMPs cloned and sequenced so far in amniochorion during preterm premature rupture of membranes (pPROM), at term not in labor and during term labor.

MATERIALS AND METHODS

Placentas were collected from women with PROM, term not in labor after C-sections and from women after term vaginal delivery. Membranes were separated from the placenta and a section away from the rupture site was selected. Amniochorion were separated from the placenta. RT-PCR was performed to study the expression pattern of MMP15 (MT2-MMP), MMP16 (MT3-MMP), MMP17 (MT4-MMP), MMP18, MMP20, MMP23, MMP24 (MT5-MMP), MMP25 (MT6-MMP), and MMP 26 using specific primers.

RESULTS

A differential pattern of expression was noted for some of the novel MMPs screened in this study in human fetal membranes. mRNA for most of the MMPs were expressed by amniochorion. MMP16 [membrane type metalloproteinase 3], MMP20 [enamelysin], and MMP26 [matrilysin] were not expressed.

CONCLUSION

Amniochorion expresses several of the MMP genes at the time of pPROM, term not in labor and during active labor. We have previously reported the expression pattern of other MMPs and their inhibitors and their potential role in PROM. These findings support our hypothesis that amniochorion has a fully functional MMP system.

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.

A role for the 72 kDa gelatinase (MMP-2) and its inhibitor (TIMP-2) in human parturition, premature rupture of membranes and intraamniotic infection

OBJECTIVE

Degradation of the extracellular matrix in fetal membranes has been implicated in the process of parturition and rupture of membranes. Matrix metalloproteinases (MMPs) are enzymes capable of degrading extracellular matrix including collagen. Tissue inhibitors of matrix metalloproteinases (TIMPs) inhibit the activity of MMPs by covalently binding to the enzymes. MMP-2 degrades Type IV collagen and TIMP-2 is its specific inhibitor. The objective of this study was to determine if human parturition, rupture of membranes (term and preterm) and microbial invasion of the amniotic cavity (MIAC) are associated with changes in the concentrations of MMP-2 and TIMP-2 in amniotic fluid.

STUDY DESIGN

A cross-sectional study was conducted with women in the following categories: 1) term with intact membranes, in labor and not in labor; 2) preterm labor and intact membranes who delivered at term, who delivered preterm and preterm labor with MIAC; 3) preterm premature rupture of membranes (PROM) with and without infection; 4) term and preterm PROM not in labor; and 5) midtrimester. MMP-2 and TIMP-2 concentrations in amniotic fluid were determined using sensitive and specific immunoassays.

RESULTS

The concentration of TIMP-2 increased with advancing gestational age (r = 0.6, p < 0.001). No correlation was found between MMP-2 concentrations and gestational age. Human parturition and rupture of membranes (term and preterm) and in patients with intact membranes were not associated with changes in the amniotic fluid MMP-2 concentrations. In contrast, 1) patients with spontaneous labor (term and preterm) had significantly lower median concentrations of TIMP-2 compared to those not in labor (p < 0.05 for both); 2) MIAC in women with preterm labor and preterm PROM was associated with a significant decrease in amniotic fluid TIMP-2 concentrations (p < 0.04 for both comparisons); 3) Rupture of the membranes (term and preterm) was also associated with a significant decrease in the amniotic fluid TIMP-2 concentrations (p < 0.05 and p < 0.03, respectively).

CONCLUSIONS

Human parturition (preterm and term), rupture of fetal membranes (term and preterm) and intraamniotic infection are associated with a significant decrease in amniotic fluid TIMP-2 concentrations.

Etiology and epidemiology of preterm premature rupture of the membranes

Preterm premature rupture of membranes continues to be a common complication of pregnancy with significant implications for perinatal outcome. Unfortunately, given the multiple risk factors that have been presented, which are reportedly associated with PPROM, attempts to reduce the incidence of this clinical event may seem daunting to the clinician. Despite this, one should attempt to address the potential risk factors that avail themselves to change. Unfortunately, although many risk factors have been identified, there are few randomized intervention trials for PPROM prevention. Examples of interventions documented to be beneficial include smoking cessation and screening for and treatment of chlamydial infections. These seem to be reasonable and logical interventions to consider in general, and may potentially have an effect on various causal agents of PPROM.

Persistent detection of alfa-fetoprotein in the vagina without overt preterm premature rupture of the membranes. Clinical and chemical characterizations

OBJECTIVES

The objectives of this study were to clinically characterize and seek risk factors for the patients with persistently detected alfa-fetoprotein (AFP) in the vagina without showing overt preterm premature rupture of the membranes (PROM).

STUDY DESIGN

The cohort study was undertaken using vaginal-cervical specimens collected consecutively between 21 and 40 weeks of gestation from 25 consenting women. Demographic, obstetric, neonatal, and laboratory data from patients with persistent positive results of AFP kit tests without showing overt leakage of amniotic fluid were compared to those from controls. Cervical levels of interleukin-1 alpha, interleukin-1 beta, interleukin-6, interleukin-8, and granulocyte elastase were measured by immunoassay, and the uterine cervix was assessed by transvaginal ultrasonography. Statistical analysis involved Fisher's exact test and Mann-Whitney U test.

RESULTS

The incidence of overt preterm PROM was significantly higher in the patients with persistently detected AFP in preterm (3 in 4 cases) than in controls (3 in 21 controls). At sampling before determination of persistently detected AFP, patients with persistently detected AFP had significantly higher cervical levels of interleukin-6 and significantly shorter cervical length than controls.

CONCLUSIONS

Patients with persistently detected AFP in the vagina without showing overt preterm PROM have the risk of overt preterm PROM. Increased levels of interleukin-6 in cervical specimens and short cervical length may be risk factors for the occurrence of persistent detection of AFP in the preterm.

Distinct molecular events suggest different pathways for preterm labor and premature rupture of membranes

OBJECTIVE

On a clinical level, the etiologies associated with premature rupture of the membranes and preterm labor are virtually identical, though these conditions end in distinctly different events. This study was designed to determine differences between preterm labor and preterm premature rupture of membranes by using molecular markers of extracellular matrix degradation and apoptosis.

STUDY DESIGN

Amniochorion and amniotic fluid samples were collected from gestational age-matched groups of women undergoing cesarean delivery before term. Samples were collected from 2 groups of women, women with premature rupture of membranes and women with preterm labor with no rupture of membranes. Changes in the expression pattern of messenger ribonucleic acid for matrix metalloproteinases (MMP), tissue inhibitor of metalloproteinases (TIMP), and pro-apoptotic (p53 and Bax) and anti-apoptotic (Bcl-2) proteins were identified by quantitative polymerase chain reaction. Enzyme-linked immunosorbent assay was used to determine the levels of these proteins in the amniotic fluid. Multiplex polymerase chain reaction was performed to study the expression of Fas-Fas ligand-associated pro-apoptotic genes. Unpaired nonparametric, 2-tailed Mann-Whitney U test was used to determine statistical significance of quantitative polymerase chain reaction and enzyme-linked immunosorbent assay (P <.05 was considered significant).

RESULTS

Quantitative polymerase chain reaction results demonstrated an increased mRNA expression for MMP2, MMP9, and MT1-MMP and a decreased expression for TIMP2 in prematurely ruptured membranes compared with preterm labor membranes. Enzyme-linked immunosorbent assay documented increases in the amniotic fluid concentrations of immunoreactive and bioactive MMP2 and MMP9 and immunoreactive MMP3 and a decreased TIMP2 concentration in fluids obtained from the premature rupture of membranes group compared with the preterm labor group. The pro-apoptotic genes p53 and bax were up-regulated in premature rupture of membranes when compared with preterm labor. Anti-apoptotic gene (Bcl-2 ) expression was increased in preterm labor membranes compared with prematurely ruptured membranes. Interleukin-18 (a pro-apoptotic cytokine) was increased in the amniotic fluid during premature rupture of membranes compared with preterm labor. Prematurely ruptured membranes also demonstrated fragmented deoxyribonucleic acid and expression of Fas and caspase 8 (apoptosis initiator), which were all absent in preterm labor membranes.

CONCLUSIONS

We have begun to delineate 2 divergent molecular pathways for premature rupture of membranes and preterm labor. Most likely, this is the beginning of the identification of differences that will become evident with the use of molecular biology.

Reactive oxygen species and preterm premature rupture of membranes-a review

Preterm premature rupture of membranes (PPROM) results initially from damage to collagen in the chorioamnion leading to a tear in the membrane. Tissue-damaging molecules called reactive oxygen species (ROS) are capable of damaging collagen in the chorioamnion that could lead to PPROM. This hypothesis is supported by epidemiological studies linking clinical conditions known to produce ROS or reduce antioxidant protection to PPROM, by in-vitro studies in which membrane segments exposed to ROS exhibited tissue alterations consistent with PPROM, and by clinical studies showing that chorioamnion and amniotic fluid samples obtained from PPROM patients exhibit excessive collagen degradation. The role of antioxidants to protect the chorioamnion from ROS damage has been demonstrated in one in-vitro study. A prospective, randomized blinded trial of antioxidant therapy during pregnancy is needed to evaluate this approach for the prevention of PPROM.

Influence of acupuncture on duration of labor

The aim of this case control study was to evaluate the thus far controversially discussed influence of acupuncture (AP) on the duration of labor. Fifty-seven women with AP treatment (group A) were included in our study after spontaneous vaginal full-term delivery. The control group included 63 women (group B). Median duration of the first stage of labor was 196 min in group A and 321 min in group B (Wilcoxon 2-sample test, p < 0.0001). Median duration of the second stage of labor was 57 min in group A and 57 min in group B (Wilcoxon 2-sample test, p = 0.82). Thirty women had a premature rupture of the membranes (PROM), in group A 66.7% and in group B 33.3% (chi2 test, p = 0.02). Women without AP (group B) received significantly more often oxytocin during the first stage of labor compared with group A women (85 and 15%, respectively, chi2 test, p = 0.01) as well as during the second stage of labor (72 and 28%, respectively, chi2 test, p = 0.03). Our study suggests that AP treatment is a recommendable form of childbirth preparation due to its positive effect on the duration of labor, namely by shortening the first stage of labor.

Matrilysin (matrix metalloproteinase 7) in parturition, premature rupture of membranes, and intrauterine infection

OBJECTIVE

Matrix metalloproteinases are enzymes capable of degrading extracellular matrix components. Matrilysin (matrix metalloproteinase 7), a novel member of this family, degrades fibronectin and proteoglycans. The objective of this study was to determine whether parturition (either term or preterm), premature rupture of the membranes, and microbial invasion of the amniotic cavity are associated with changes in the amniotic fluid concentration of matrilysin.

STUDY DESIGN

A cross-sectional study was conducted with 275 women in the following categories: (1) second trimester, (2) term not in labor, (3) term in labor, (4) term with microbial invasion of the amniotic cavity, (5) preterm labor with intact membranes without microbial invasion of the amniotic cavity who delivered at term, (6) preterm labor without microbial invasion of the amniotic cavity who delivered preterm, (7) preterm labor with microbial invasion of the amniotic cavity, (8) preterm premature rupture of membranes with and without microbial invasion of the amniotic cavity, and (9) term premature rupture of membranes not in labor and without microbial invasion of the amniotic cavity. Matrilysin concentrations were measured with a sensitive specific immunoassay that was validated for amniotic fluid.

RESULTS

Matrilysin was detectable in 97.4% (268/275) of the samples. The concentration of matrilysin increased with advancing gestational age (r = 0.8; P <.001). Parturition at term was not associated with a significant increase in amniotic fluid concentration of matrilysin. Preterm parturition in the absence of microbial invasion of the amniotic cavity was associated with a significant increase in amniotic fluid concentration of matrilysin (preterm labor with preterm delivery: median, 1.7 ng/mL; range, 0.45-21.6 mg/mL; vs preterm labor with term delivery: median, 1.2 ng/mL; range, 0.17-42. 1 ng/mL; P <.05). Premature rupture of membranes without microbial invasion of the amniotic cavity (either term or preterm) was not associated with a significant change in the amniotic fluid matrilysin concentration. Intra-amniotic infection was associated with a significant increase in amniotic fluid matrilysin among both patients with preterm labor and patients with preterm premature rupture of membranes (preterm labor with microbial invasion of the amniotic cavity: median, 3.2 ng/mL; range, 0.16-21.9 ng/mL; vs preterm labor and delivery without microbial invasion of the amniotic cavity: median, 1.7 ng/mL; range, 0.45-21.6 ng/mL; vs preterm labor with term delivery: median, 1.2 ng/mL; range, 0.17-42. 1 ng/mL; P <.01 for each comparison; and preterm premature rupture of membranes without microbial invasion of the amniotic cavity: median, 1.7 ng/mL; range, 0.29-13.9 ng/mL; vs preterm premature rupture of membranes with microbial invasion of the amniotic cavity: median, 3.6 ng/mL; range, 0.59-20.3 ng/mL; P <.01).

CONCLUSION

Matrilysin is a physiologic constituent of amniotic fluid, and its concentration increases with advancing gestational age. Microbial invasion of the amniotic cavity in preterm gestations was associated with a significant increase in amniotic fluid concentration of matrilysin. Matrilysin therefore may play a role in the host defense mechanism.

Programmed cell death (apoptosis) as a possible pathway to metalloproteinase activation and fetal membrane degradation in premature rupture of membranes

OBJECTIVE

Increased matrix metalloproteinase 2 expression and activity are associated with premature rupture of fetal membranes. A proapoptotic protein produced in response to deoxyribonucleic acid fragmentation, p53, can bind to the matrix metalloproteinase 2 gene promoter and cause increased gene expression. It promotes apoptosis by inducing the expression of the proapoptotic bax gene and inhibiting the antiapoptotic bcl-2 gene. This study was undertaken to investigate the expression pattern of apoptotic elements in pregnancy complications that may cause increased expression of the gene for matrix metalloproteinase 2.

STUDY DESIGN

Amniochorial membranes were collected from the following groups of women: (1) women with premature rupture of fetal membranes, (2) women with preterm labor and intact membranes, and (3) women with term labor after vaginal delivery. Deoxyribonucleic acid fragmentation was tested with ligation-mediated polymerase chain reaction and the terminal deoxynucleotidyl transferase-mediated biotinylated deoxyribonucleoside triphosphate end-labeling assay. Matrix metalloproteinase 2, p53, bcl-2, and bax gene expression patterns were studied with quantitative competitive polymerase chain reaction. Statistical analysis was performed with the Tukey-Kramer multiple comparison test.

RESULTS

Quantitative competitive polymerase chain reaction documented a 10-fold increase in the expression of the gene for matrix metalloproteinase 2 in premature rupture of fetal membranes with respect to term and preterm labor. This induction coincided with an increase in the expressions of the proapoptotic genes p53 and bax and a drop in the expression of the antiapoptotic gene bcl-2. Ligation-mediated polymerase chain reaction revealed deoxyribonucleic acid fragmentation in specimens from premature rupture of fetal membranes and not in those from preterm labor or labor at term. Histochemical analysis documented fragmented deoxyribonucleic acid in chorionic and amniotic cells.

CONCLUSION

This study suggests that apoptosis is associated with premature rupture of fetal membranes. Deoxyribonucleic acid fragmentation, associated with elevations in the levels of the two proapoptotic gene products evaluated (p53 and bax ) and a drop in the level of the antiapoptotic bcl-2, was seen in premature rupture of the fetal membranes. Induction of matrix metalloproteinase 2 may be a function of p53 gene expression increase in premature rupture of fetal membranes.