Matrix metalloproteinase 3 in parturition, premature rupture of the membranes, and microbial invasion of the amniotic cavity

Matrix metalloproteinase-3 in preeclamptic and normotensive pregnancies complicated by foetal growth restriction

The aim of the present study was to assess the interrelationships between the level of matrix metalloproteinase-3 in the blood serum of pregnant women and the occurrence of pregnancy complications in the form of foetal growth restriction, idiopathic or in the course of preeclampsia.

Methods

A total of 245 patients were included in the study. 65 of them are normotensive patients with idiopathic foetal growth restriction (FGR group). 115 women were diagnosed with severe preeclampsia. In the group of women with preeclampsia, there were 51 patients with adequate for gestational age foetal growth and 64 patients with the foetal growth restriction in the course of severe preeclampsia. The control group consisted of 65 healthy patients with normal pregnancy course, with no cardiovascular disorders at the present and in the history, normal blood pressure and normal intrauterine foetal growth. Matrix metalloproteinase-3 (MMP-3) in maternal circulation were determined by ELISA method.

Results

In our studies, we observed elevated levels of matrix metalloproteinase-3 in preeclamptic women with pregnancies complicated by FGR and significantly lower in the group of normotensive women with idiopathic FGR. The mean values of MMP-3 were 33.50 ± 65.74 ng/mL [Median (min-max) 19.19 (2.05-454.53)] in the Control group, 21.22 ± 23.28 ng/mL [Median (min-max) 16.39 (3.45-156.29)] in the FGR group, 35.96 ± 46.14 ng/mL [Median (min-max) 25.21 (4.16-253.05)] in the P group and 52.81 ± 61.61 ng/mL [Median (min-max) 32.83 (5.06-314.14)] in preeclamptic women with FGR (group PI) respectively.The assessment of MMP-3 in the serum of women with pregnancies complicated by intrauterine foetal growth restriction with normal values of blood pressure and in the group of preeclamptic patients in relation to healthy pregnant women with uncomplicated pregnancies and in relation to preeclamptic patients with normal intrauterine foetal growth is the novelty of this study. Such a strict definition of each research group seems to allow for the assessment of each pregnancy complication separately.

Conclusion

It seems that higher levels of MMP-3 in preeclamptic women may suggest the need for observation towards the risk of lower birth weight of newborns. This necessitates further research and a better integration in the clinical practice.

The amniotic fluid proteome changes with term labor and informs biomarker discovery in maternal plasma

The intra-uterine components of labor, namely, myometrial contractility, cervical ripening, and decidua/membrane activation, have been extensively characterized and involve a local pro-inflammatory milieu of cellular and soluble immune mediators. Targeted profiling has demonstrated that such processes extend to the intra-amniotic space, yet unbiased analyses of the proteome of human amniotic fluid during labor are lacking. Herein, we utilized an aptamer-based platform to characterize 1,310 amniotic fluid proteins and found that the proteome undergoes substantial changes with term labor (251 proteins with differential abundance, q < 0.1, and fold change > 1.25). Proteins with increased abundance in labor are enriched for immune and inflammatory processes, consistent with prior reports of labor-associated changes in the intra-uterine space. By integrating the amniotic fluid proteome with previously generated placental-derived single-cell RNA-seq data, we demonstrated the labor-driven upregulation of signatures corresponding to stromal-3 and decidual cells. We also determined that changes in amniotic fluid protein abundance are reflected in the maternal plasma proteome. Collectively, these findings provide novel insights into the amniotic fluid proteome in term labor and support its potential use as a source of biomarkers to distinguish between true and false labor by using maternal blood samples.

Matrix metalloproteinases in preterm prelabor rupture of membranes in the setting of chorioamnionitis: A scoping review

Fetal or gestational membranes extend from the placenta to enclose the fetus and amniotic fluid. While the membranes spontaneously rupture at term in normal pregnancies, they can rupture prematurely before the onset of labor, termed preterm prelabor rupture of membranes (PPROM). PPROM can be triggered by bacterial infection or sterile inflammation in the membranes, known as chorioamnionitis (CAM). The membranes derive their tensile strength from a collagen-rich extracellular matrix (ECM); as such, understanding the enzymes and processes that can degrade the membrane ECM are of paramount importance. Matrix metalloproteinases (MMPs) are a class of enzymes capable of degrading collagen and other components of the ECM, and can be induced by inflammation. We used a scoping review to address the question of how MMP activity is associated with PPROM, particularly their induction due to sterile or nonsterile CAM. We have found that the most studied MMPs in PPROM were MMPs 2, 8, and 9. Additionally, some MMPs are constitutively active, while others are induced by inflammation. Mechanistic studies of the pathways that induce MMP activation are sparse, and this area is ripe for future studies. Targeting MMP activation could be a future strategy to delay or prevent PPROM.

Prognostic Markers for Chorioamnionitis: IL-6, TNF-α, and MMP-8 in Vaginally Obtained Amniotic Fluid

Background. Earlier chorioamnionitis diagnosis is crucial to improve maternal and neonatal health outcomes. This study was conducted to evaluate the inlerleukin-6 (IL-6), tumor necrosis factor α (TNF-α), and matrix metalloproteinase 8 (MMP-8) levels in vaginally obtained amniotic fluid to investigate their prognostic value and to determine the most appropriate cut-off values for the prediction of chorioamnionitis. Methods. This case control study included women who were diagnosed with preterm premature rupture of the membranes before 34 weeks of gestation and were admitted to Vilnius University Hospital Santaros Klinikos. Free-leaking amniotic fluid was obtained vaginally with a sterile speculum less than 48h before delivery. Amniotic fluid IL-6, TNF-α, and MMP-8 levels were determined by the Enzyme Linked Immunosorbent Assay. Diagnosis of chorioamnionitis was confirmed by histological examination of the placenta and membranes after delivery. Results. The study included 156 women, 65 patients in the histological chorioamnionitis group (Group I) and 91 in a group without diagnosed histological chorioamnionitis (Group II). The median concentrations of IL-6, MMP-8, and TNF-α in amniotic fluid were statistically significantly higher in Group I than in Group II (p-value < 0.001). The area under the curve of TNF-α and MMP-8 were higher than the area under the curve of IL-6 (0.91, 0.89, and 0.81, respectively). No statistically significant difference was found when comparing the receiver operating characteristic (ROC) curves of TNF-α and MMP-8. The optimum cut-off values for the prediction of chorioamnionitis were found to be 1389.82 pg/mL for IL-6, 21.17 pg/mL for TNF-α, and 172.53 ng/mL for MMP-8. The sensitivity, specificity, positive prognostic value (PPV), and negative prognostic value (NPV) of the IL-6 cut-off for chorioamnionitis were 88%, 70%, 67%, and 89%, respectively. The sensitivity, specificity, PPV, and NPV of the TNF-α cut-off were 88%, 84%, 79%, and 90%, respectively. The sensitivity, specificity, PPV, and NPV of the MMP-8 cut-off were 80%, 87%, 81%, and 86%, respectively. Conclusions. The vaginally obtained amniotic fluid IL-6, MMP-8, and TNF-α seem to be good predictors for chorioamnionitis of patients with preterm premature rupture of membranes before 34 weeks of gestation. The noninvasive technique of sampling amniotic fluid could be alternative method to invasive amniocentesis.

The diagnostic performance of the beta-glucan assay in the detection of intra-amniotic infection with Candida species

INTRODUCTION

A bioassay based on the detection of beta-glucan, a constituent of the cell wall of fungi, has been successfully used to diagnose fungal infections in a variety of biological fluids but not yet in the amniotic fluid.

OBJECTIVE

To determine the diagnostic performance of a beta-glucan bioassay in the detection of Candida species in the amniotic fluid of women who either did or did not have an intrauterine contraceptive device (IUD) in place during an episode of spontaneous preterm parturition.

METHODS

The study population comprised women who had a singleton pregnancy without congenital or chromosomal abnormalities, who experienced preterm labor or preterm prelabor rupture of the fetal membranes, and who underwent a transabdominal amniocentesis for clinical indications. Samples of amniotic fluid were cultured for aerobic and anaerobic bacteria, genital mycoplasmas, and Candida species, and assayed for beta-glucan, using the (1→3)-beta-d-glucan-specific Limulus amebocyte lysate test (beta-glucan assay) in all cases. Amniotic fluid interleukin (IL)-6 assay results were also available for all cases. The beta-glucan assay takes about 1 hour to run: a concentration >80 pg/mL was considered positive for fungi. Sterile intra-amniotic inflammation of the amniotic cavity was defined by the presence of an amniotic fluid IL-6 concentration ≥2.6 ng/mL and a negative amniotic fluid culture.

RESULTS

(1) One hundred ninety-seven (197) women met the study criteria, of whom 58 (29.4%) had an IUD in place; (2) 20 (10.2%) women had a culture of proven intra-amniotic Candida species-related infection, 19 of whom had a positive beta-glucan assay [sensitivity, 95% (19/20; 95% confidence interval (CI): 75.1-99.9%)]; and (3) the specificity of the beta-glucan assay was 75.1% [133/177; 95% CI: 68.1-99.9%]. It was affected by the presence of nonfungal intra-amniotic infections and an IUD, but not by the presence of sterile intra-amniotic inflammation, and there was a significant interaction between the presence of an IUD and nonfungal intra-amniotic infections (estimated for the interaction effect = 2.1923, p value =.026). The assay's specificity was reduced when nonfungal intra-amniotic infections were diagnosed but only in women who did not have an IUD. Among women without an IUD, the assay's specificity was 91.4% (117/128); it was 93% (106/114) for those without intra-amniotic infection, and 78.6% (11/14) for those with a nonfungal intra-amniotic infection; the difference was not significant (p = .09). Among women with an IUD, the assay's specificity was 32.7% (16/49); 42.9% (9/21) for those with a nonfungal intra-amniotic infection; and 25% (7/28) for those without intra-amniotic infection; and the difference was significant (p = .03).

CONCLUSIONS

The beta-glucan assay is a sensitive, rapid, point-of-care test used to diagnose intra-amniotic Candida species-related infection, and it has a high specificity in pregnant women who did not have an IUD in place.

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.

Expression of Matrix Metalloproteinases in the Mouse Uterus and Human Myometrium During Pregnancy, Labor, and Preterm Labor

BACKGROUND

Uterine extracellular matrix (ECM) remodeling occurs throughout pregnancy and at parturition. Imbalanced availability of key mediators in ECM degradation, namely, matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs), is implicated in the pathogenesis of preterm labor (PTL).

OBJECTIVES

Examine the expression of MMPs and their inhibitors TIMPs in (a) the mouse uterus throughout normal gestation, at labor, and during inflammation-induced PTL and (b) the human term and preterm myometrium.

METHODS

The expression of Mmp-2/9/3/10 and Timp-1/2 was determined in the uterus of C57BL/6 mice (n = 6/group) during pregnancy (on days (d) 5, 8, 12, 15, 17, and 18), at normal labor, and during lipopolysaccharide-induced PTL (n = 6/group). The expression of MMP-10 and TIMP-1 was determined in human term and preterm myometrium before the onset of labor (TNL, n = 7; PTNL, n = 7) and during active labor (TL, n = 8; PTL, n = 8). Gene expression and tissue localization were assessed by quantitative polymerase chain reaction and immunohistochemistry, respectively.

RESULTS

Mmp-10 was higher during murine labor (53-fold vs early pregnancy) in contrast to Mmp-2/3/9 and Timp-1, the expression of which reached a nadir at labor ( P < .001 vs d5 [ Mmp-2/ 9] or P < .05 vs d8 [ Mmp-3 and Timp-1]). The Mmp-3/10 and Timp-1 were localized to the uterine epithelium and stroma/myometrium. In the human myometrium, TIMP-1 messenger RNA was higher and MMP-10 was lower in TL versus TNL ( P < .05), PTL ( P < .001), and PTNL ( P < .001). MMP-10 and TIMP-1 were localized to the myometrial smooth muscle cells, interstitial fibroblasts, and inflammatory cells.

CONCLUSIONS

These data implicate MMP-3, TIMP-1, and MMP-10 in the uterine ECM remodeling during physiological and pathological parturition.

CXCL10 and IL-6: Markers of two different forms of intra-amniotic inflammation in preterm labor

Problem

To determine whether amniotic fluid (AF) CXCL10 concentration is associated with histologic chronic chorioamnionitis in patients with preterm labor (PTL) and preterm prelabor rupture of the membranes (PROM).

Method of Study

This study included 168 women who had an episode of PTL or preterm PROM. AF interleukin (IL)‐6 and CXCL10 concentrations were determined by immunoassay.

Results

(i) Increased AF CXCL10 concentration was associated with chronic (OR: 4.8; 95% CI: 1.7‐14), but not acute chorioamnionitis; (ii) increased AF IL‐6 concentration was associated with acute (OR: 4.2; 95% CI: 1.3‐13.7) but not chronic chorioamnionitis; and (iii) an increase in AF CXCL10 concentration was associated with placental lesions consistent with maternal anti‐fetal rejection (OR: 3.7; 95% CI: 1.3‐10.4). (iv) All patients with elevated AF CXCL10 and IL‐6 delivered preterm.

Conclusion

Increased AF CXCL10 concentration is associated with chronic chorioamnionitis or maternal anti‐fetal rejection, whereas increased AF IL‐6 concentration is associated with acute histologic chorioamnionitis.

Predictive value of vaginal IL-6 and TNFα bedside tests repeated until delivery for the prediction of maternal-fetal infection in cases of premature rupture of membranes

OBJECTIVE

Examine the predictive value for maternal-fetal infection of routine bedside tests detecting the proinflammatory cytokines, TNFα and IL-6, in the vaginal secretions of women with premature rupture of the membranes (PROM).

STUDY DESIGN

This prospective two-center cohort study included all women hospitalized for PROM over a 2-year period. A bedside test assessed IL-6 and TNFα in vaginal secretions. Both centers routinely tested CRP and leukocytes, assaying both in maternal serum, and analyzed vaginal bacterial flora; all samples were repeated twice weekly until delivery.

RESULTS

The study included 689 women. In cases of preterm PROM (PPROM) before 37 weeks (n=184), a vaginal sample positive for one or more bacteria was the only marker associated with early neonatal infection (OR 5.6, 95%CI; 2.0-15.7). Its sensitivity was 82% (95%CI; 62-94) and its specificity 56% (95%CI; 47-65). All positive markers of infection were associated with the occurrence of chorioamnionitis. In cases of PROM from 37 weeks onward (n=505), only CRP >5mg/dL was associated with early neonatal infection (OR=8.3, 95%CI; 1.1-65.4) or clinical chorioamnionitis (OR=6.8, 95%CI; 1.5-30.0). The sensitivity of CRP >5mg/dL was 91% (95%CI; 59-100) and its specificity 45% (95%CI; 40-51) for predicting early neonatal infection, and 89% (95%CI; 65-99) and 46% (95%CI; 41-51), respectively, for predicting clinical chorioamnionitis.

CONCLUSION

The association of vaginal cytokines with maternal-fetal infection is weak and thus prevents their use as a good predictor of maternal-fetal infection. CRP and vaginal samples may be useful for identifying a group of women at low risk of infection.

Roles and regulation of the matrix metalloproteinase system in parturition

Significant tissue destruction, repair, and remodeling are involved in parturition, which involves fetal membrane rupture, cervical ripening, and uterine contraction and its subsequent involution. Extracellular matrix degradation and remodeling by proteolytic enzymes, such as matrix metalloproteinases (MMPs), are required for the final steps of parturition. MMPs participate in physiological degradation and remodeling through their proteolytic activities on specific substrates, and are balanced by the action of their inhibitors. Disruption to this balance can result in pathological stress that ends with preterm or post-term birth or pre-eclampsia. In this review, we examine the roles and regulation of the MMP system in physiological and pathological labor, and propose a model that illustrates the mechanisms by which the MMP system contributes to these processes.

Clinical chorioamnionitis at term IV: the maternal plasma cytokine profile

INTRODUCTION

Fever is a major criterion for clinical chorioamnionitis; yet, many patients with intrapartum fever do not have demonstrable intra-amniotic infection. Some cytokines, such as interleukin (IL)-1, IL-6, interferon-gamma (IFN-γ), and tumor necrosis factor alpha (TNF-α), can induce a fever. The objective of this study was to determine whether maternal plasma concentrations of cytokines could be of value in the identification of patients with the diagnosis of clinical chorioamnionitis at term who have microbial-associated intra-amniotic inflammation.

METHODS

A retrospective cross-sectional study was conducted, including patients with clinical chorioamnionitis at term (n=41; cases) and women in spontaneous labor at term without clinical chorioamnionitis (n=77; controls). Women with clinical chorioamnionitis were classified into three groups according to the results of amniotic fluid culture, broad-range polymerase chain reaction coupled with electrospray ionization mass spectrometry (PCR/ESI-MS), and amniotic fluid IL-6 concentration: 1) no intra-amniotic inflammation; 2) intra-amniotic inflammation without detectable microorganisms; or 3) microbial-associated intra-amniotic inflammation. The maternal plasma concentrations of 29 cytokines were determined with sensitive and specific V-PLEX immunoassays. Nonparametric statistical methods were used for analysis, adjusting for a false discovery rate of 5%.

RESULTS

1) The maternal plasma concentrations of pyrogenic cytokines (IL-1β, IL-2, IL-6, IFN-γ, and TNF-α) were significantly higher in patients with clinical chorioamnionitis at term than in those with spontaneous term labor without clinical chorioamnionitis; 2) the maternal plasma concentrations of cytokines were not significantly different among the three subgroups of patients with clinical chorioamnionitis (intra-amniotic inflammation with and without detectable bacteria and those without intra-amniotic inflammation); and 3) among women with the diagnosis of clinical chorioamnionitis, but without evidence of intra-amniotic inflammation, the maternal plasma concentrations of pyrogenic cytokines were significantly higher than in patients with spontaneous labor at term. These observations suggest that a fever can be mediated by increased circulating concentrations of these cytokines, despite the absence of a local intra-amniotic inflammatory response.

CONCLUSIONS

1) The maternal plasma concentrations of pyrogenic cytokines (e.g. IL-1β, IL-2, IL-6, IFN-γ, and TNF-α) are higher in patients with intra-partum fever and the diagnosis of clinical chorioamnionitis at term than in those in spontaneous labor at term without a fever; and 2) maternal plasma cytokine concentrations have limited value in the identification of patients with bacteria in the amniotic cavity. Accurate assessment of the presence of intra-amniotic infection requires amniotic fluid analysis.

Clinical chorioamnionitis at term II: the intra-amniotic inflammatory response

OBJECTIVE

Recent studies indicate that clinical chorioamnionitis is a heterogeneous condition and only approximately one-half of the patients have bacteria in the amniotic cavity, which is often associated with intra-amniotic inflammation. The objective of this study is to characterize the nature of the inflammatory response within the amniotic cavity in patients with clinical chorioamnionitis at term according to the presence or absence of 1) bacteria in the amniotic cavity and 2) intra-amniotic inflammation.

MATERIALS AND METHODS

A retrospective cross-sectional case-control study was conducted to examine cytokine and chemokine concentrations in the amniotic fluid (AF). Cases consisted of women with clinical chorioamnionitis at term (n=45). Controls were women with uncomplicated pregnancies at term who did not have intra-amniotic inflammation and were in labor (n=24). Women with clinical chorioamnionitis were classified according to the results of AF cultures, broad-range polymerase chain reaction coupled with electrospray ionization mass spectrometry, and AF concentration of interleukin-6 (IL-6) into those: 1) without intra-amniotic inflammation, 2) with microbial-associated intra-amniotic inflammation, and 3) with intra-amniotic inflammation without detectable bacteria. The AF concentrations of 29 cytokines/chemokines were determined using sensitive and specific V-PLEX immunoassays.

RESULTS

1) The AF concentrations of pro- and anti-inflammatory cytokines/chemokines such as interferon gamma (IFN-γ), tumor necrosis factor alpha (TNF-α), interleukin-4 (IL-4), macrophage inflammatory protein-1 beta (MIP-1β), and interleukin-8 (IL-8) (except Eotaxin-3) were significantly higher in women with clinical chorioamnionitis at term than in controls (term labor without intra-amniotic inflammation); 2) patients with microbial-associated intra-amniotic inflammation, and those with intra-amniotic inflammation without detectable bacteria, had a dramatic differential expression of cytokines and chemokines in AF compared to patients with spontaneous labor without intra-amniotic inflammation. However, no difference could be detected in the pattern of the intra-amniotic inflammatory response between patients with intra-amniotic inflammation with and without detectable bacteria; and 3) in patients with clinical chorioamnionitis at term but without intra-amniotic inflammation, the behavior of cytokines and chemokines in the AF was similar to those in spontaneous labor at term.

CONCLUSIONS

Patients with clinical chorioamnionitis who had microbial-associated intra-amniotic inflammation or intra-amniotic inflammation without detectable bacteria had a dramatic upregulation of the intra-amniotic inflammatory response assessed by amniotic fluid concentrations of cytokines. A subset of patients with term clinical chorioamnionitis does not have intra-amniotic infection/inflammation, as demonstrated by elevated AF concentrations of inflammation-related proteins, when compared to women in term labor with uncomplicated pregnancies, suggesting over-diagnosis. These observations constitute the first characterization of the cytokine/chemokine network in the amniotic cavity of patients with clinical chorioamnionitis at term.

Matrix Metalloproteinase-3 (MMP-3) Is an Endogenous Activator of the MMP-9 Secreted by Placental Leukocytes: Implication in Human Labor

Background

The activity of matrix degrading enzymes plays a leading role in the rupture of the fetal membranes under normal and pathological human labor, and matrix metalloproteinase-9 (MMP-9) it is considered a biomarker of this event. To gain further insight into local MMP-9 origin and activation, in this study we analyzed the contribution of human placental leukocytes to MMP-9 secretion and explored the local mechanisms of the pro-enzyme activation.

Methods

Placental blood leukocytes were obtained from women at term gestation without labor and maintained in culture up to 72 h. MMP-9 activity in the culture supernatants was determined by zymography and using a specific substrate. The presence of a potential pro-MMP-9 activator in the culture supernatants was monitored using a recombinant biotin-labeled human pro-MMP-9. To characterize the endogenous pro-MMP-9 activator, MMP-1, -3, -7 and -9 were measured by multiplex assay in the supernatants, and an inhibition assay of MMP-9 activation was performed using an anti-human MMP-3 and a specific MMP-3 inhibitor. Finally, production of MMP-9 and MMP-3 in placental leukocytes obtained from term pregnancies with and without labor was assessed by immunofluorescence.

Results

Placental leukocytes spontaneously secreted pro-MMP-9 after 24 h of culture, increasing significantly at 48 h (P≤0.05), when the active form of MMP-9 was detected. Culture supernatants activated the recombinant pro-MMP-9 showing that placental leukocytes secrete the activator. A significant increase in MMP-3 secretion by placental leukocytes was observed since 48 h in culture (P≤0.05) and up to 72 h (P≤0.001), when concentration reached its maximum value. Specific activity of MMP-9 decreased significantly (P≤0.005) when an anti-MMP-3 antibody or a specific MMP-3 inhibitor were added to the culture media. Placental leukocytes from term labor produced more MMP-9 and MMP-3 compared to term non-labor cells.

Conclusions

In this work we confirm that placental leukocytes from human term pregnancies are able to secrete large amounts of MMP-9, and that the production of the enzyme it is enhanced by labor. We also demonstrate for the first time that endogenous MMP-3 plays a major role in MMP-9 activation process. These findings support the contribution of placental leukocytes to create the collagenolytic microenvironment that induces the rupture of the fetal membranes during human labor.

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

OBJECTIVE

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

STUDY DESIGN

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

RESULTS

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

CONCLUSION

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

Evidence of perturbations of the cytokine network in preterm labor

OBJECTIVE

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

STUDY DESIGN

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

RESULTS

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

CONCLUSIONS

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

Chorioamniotic membrane senescence: a signal for parturition?

OBJECTIVE

Senescence is an important biological phenomenon involved in both physiologic and pathologic processes. We propose that chorioamniotic membrane senescence is a mechanism associated with human parturition. The present study was conducted to explore the association between senescence and normal term parturition by examining the morphologic and biochemical evidences in chorioamniotic membranes.

STUDY DESIGN

Chorioamniotic membranes were collected from normal term deliveries; group 1: term labor and group 2: term, not in labor. Senescence-related morphologic changes were determined by transmission electron microscopy and biochemical changes were studied by senescence-associated (SA) β-galactosidase staining. Amniotic fluid samples collected from both term labor and term not in labor were analyzed for 14 SA secretory phenotype (SASP) markers.

RESULTS

Morphologic evidence of cellular senescence (enlarged cells and organelles) and a higher number of SA β-galactosidase-stained amnion and chorion cells were observed in chorioamniotic membranes obtained from women in labor at term, when compared to term not in labor. The concentration of proinflammatory SASP markers (granulocyte macrophage colony-stimulating factor, interleukin-6 and -8) was significantly higher in the amniotic fluid of women in labor at term than women not in labor. In contrast, SASP factors that protect against cell death (eotaxin-1, soluble Fas ligand, osteoprotegerin, and intercellular adhesion molecule-1) were significantly lower in the amniotic fluid samples from term labor.

CONCLUSION

Morphologic and biochemical features of senescence were more frequent in chorioamniotic membranes from women who experienced term labor. Senescence of chorioamniotic membranes were also associated with amniotic fluid SASP markers.

A point of care test for the determination of amniotic fluid interleukin-6 and the chemokine CXCL-10/IP-10

OBJECTIVE

Intra-amniotic inflammation is a mechanism of disease implicated in preterm labor, preterm prelabor rupture of membrane, cervical insufficiency, a short cervix, and idiopathic vaginal bleeding. Determination of interleukin (IL)-6 with immunoassays has been proven for more than two decades to be an excellent method for the detection of intra-amniotic inflammation. However, assessment of IL-6 for this indication has been based on immunoassays which are not clinically available, and this has been an obstacle for the implementation of this test in clinical practice. It is now possible to obtain results within 20 min with a point of care (POC) test which requires minimal laboratory support. This test is based on lateral flow-based immunoassay. The objective of this study was to compare amniotic fluid (AF) IL-6 and interferon-γ - inducible protein 10 (IP-10 or CXCL-10) concentrations determined using lateral flow-based immunoassay or POC test and standard enzyme-linked immunosorbent assay (ELISA) techniques.

MATERIAL AND METHODS

AF samples were collected from patients with singleton gestations and symptoms of preterm labor (n = 20). AF IL-6 and IP-10 concentrations were determined by lateral flow-based immunoassay and ELISA. Intra-amniotic inflammation was defined as AF IL-6 ≥ 2.6 ng/ml. AF IL-6 and IP-10 concentrations between two assays were compared.

RESULTS

(1) Lateral flow-based immunoassay POC AF IL-6 and IP-10 test results were strongly correlated with concentrations of this cytokine/chemokine determined by ELISA (Spearman's ρ = 0.92 and 0.83, respectively, both p < 0.0001); (2) AF IL-6 concentrations determined by the lateral flow-based immunoassay test were, on average, 30% lower than those determined by ELISA, and the median difference was statistically significant (p < 0.0001); and (3) in contrast, AF IP-10 concentrations determined by the lateral flow-based immunoassay test were, on average, only 7% lower than those determined by ELISA, and the median difference was not statistically significant (p = 0.81).

CONCLUSION

AF IL-6 and IP-10 concentrations determined using a lateral flow-based immunoassay POC are strongly correlated with concentrations determined by conventional ELISA. This justifies further studies about the diagnostic indices and predictive values of this POC test.

Sterile and microbial-associated intra-amniotic inflammation in preterm prelabor rupture of membranes

OBJECTIVE

The objectives of this study were to: (1) determine the amniotic fluid (AF) microbiology of patients with preterm prelabor rupture of membranes (PROM); and (2) examine the relationship between intra-amniotic inflammation with and without microorganisms (sterile inflammation) and adverse pregnancy outcomes in patients with preterm PROM.

METHODS

AF samples obtained from 59 women with preterm PROM were analyzed using cultivation techniques (for aerobic and anaerobic bacteria as well as genital mycoplasmas) and with broad-range polymerase chain reaction coupled with electrospray ionization mass spectrometry (PCR/ESI-MS). AF concentration of interleukin-6 (IL-6) was determined using ELISA. Results of both tests were correlated with AF IL-6 concentrations and the occurrence of adverse obstetrical/perinatal outcomes.

RESULTS

(1) PCR/ESI-MS, AF culture, and the combination of these two tests each identified microorganisms in 36% (21/59), 24% (14/59) and 41% (24/59) of women with preterm PROM, respectively; (2) the most frequent microorganisms found in the amniotic cavity were Sneathia species and Ureaplasma urealyticum; (3) the frequency of microbial-associated and sterile intra-amniotic inflammation was overall similar [ 29% (17/59)]: however, the prevalence of each differed according to the gestational age when PROM occurred; (4) the earlier the gestational age at preterm PROM, the higher the frequency of both microbial-associated and sterile intra-amniotic inflammation; (5) the intensity of the intra-amniotic inflammatory response against microorganisms is stronger when preterm PROM occurs early in pregnancy; and (6) the frequency of acute placental inflammation (histologic chorioamnionitis and/or funisitis) was significantly higher in patients with microbial-associated intra-amniotic inflammation than in those without intra-amniotic inflammation [93.3% (14/15) versus 38% (6/16); p = 0.001].

CONCLUSIONS

(1) The frequency of microorganisms in preterm PROM is 40% using both cultivation techniques and PCR/ESI-MS; (2) PCR/ESI-MS identified microorganisms in the AF of 50% more women with preterm PROM than AF culture; and (3) sterile intra-amniotic inflammation was present in 29% of these patients, and it was as or more common than microbial-associated intra-amniotic inflammation among those presenting after, but not before, 24 weeks of gestation.

A transcervical amniotic fluid collector: a new medical device for the assessment of amniotic fluid in patients with ruptured membranes

AIM

To describe a new device for the transcervical collection of amniotic fluid (AF) in patients with ruptured membranes, and to compare the concentration of proteins in fluid retrieved by transabdominal amniocentesis and the transcervical AF collector.

STUDY DESIGN

Paired AF samples were collected in patients with preterm prelabor rupture of membranes (PROM) (n=11) by transabdominal amniocentesis and with the transcervical AF collector (Yoon's AF Collector™). Three proteins known to have high concentrations in AF [α-fetoprotein (AFP), β-human chorionic gonadotrophin (β-hCG), and prolactin] were measured.

RESULTS

(1) There was a significant correlation between the concentrations of analytes in AF obtained by transabdominal amniocentesis and by the transcervical AF collector (r=0.94, P<0.001 for AFP; r=0.96, P<0.001 for β-hCG; r=0.72, P<0.05 for prolactin); (2) Bland-Altman plots showed no evidence of heteroscedasticity between transabdominal or transcervical AF concentrations of these markers.

CONCLUSIONS

There was a strong correlation between the concentrations of proteins in AF collected by amniocentesis or with the transcervical device.

Is there a role for probiotics in the prevention of preterm birth?

Preterm birth (PTB) continues to be a global health challenge. An over-production of inflammatory cytokines and chemokines, as well as an altered maternal vaginal microbiome has been implicated in the pathogenesis of inflammation/infection-associated PTB. Lactobacillus represents the dominant species in the vagina of most healthy pregnant women. The depletion of Lactobacillus in women with bacterial vaginosis (BV) has been associated with an increased risk of PTB. It remains unknown at what point an aberrant vaginal microbiome composition specifically induces the cascade leading to PTB. The ability of oral or vaginal lactobacilli probiotics to reduce BV occurrence and/or dampen inflammation is being considered as a means to prevent PTB. Certain anti-inflammatory properties of lactobacilli suggest potential mechanisms. To date, clinical studies have not been powered with sufficiently high rates of PTB, but overall, there is merit in examining this promising area of clinical science.

Escherichia coli-induced temporal and differential secretion of heat-shock protein 70 and interleukin-1β by human fetal membranes in a two-compartment culture system

INTRODUCTION

Escherichia coli is recognized as an etiological bacteria associated with chorioamnionitis and the preterm premature rupture of fetal membranes. This pathological condition induces pro-inflammatory cytokines and degradative metalloproteinases, which are considered biological markers secreted in an acute stage of infection. Heat-shock proteins (HSPs) are an important component of the innate immunity response and are found in different pathological conditions. They have not been previously measured in human fetal membranes in response to infectious conditions. We hypothesized that the choriodecidual tissue and amniotic epithelium secreted temporal and differential Hsp-60, Hsp-70, and interleukin (IL)-1β mediated by E. coli infection.

METHODS

Fetal membranes were mounted in a two-compartment culture system and infected with two passes of live E. coli at different doses (10², 10⁴, 10⁵, and 10⁶ colony-forming units (CFU)/mL) and intervals of incubation (3, 6, and 24 h). The culture medium was collected, and Hsp-60, Hsp-70, and IL-1β were assessed using the enzyme-linked immunosorbent assay (ELISA) method.

RESULTS

After 3 and 6 h of infection, E. coli induced an increase in Hsp-70 secretion in the choriodecidual tissue. However, after 24 h of incubation, Hsp-70 was downregulated and we observed an increase in IL-1β secretion. By contrast, E. coli induced a lower Hsp-60 secretion in the amnion compared to Hsp-70.

DISCUSSION

Human fetal membranes responded actively to E. coli infection, with an increase in Hsp-70 during the first hours of infection. After 24 h, there was an increase in the liberation of IL-1β.

Bacteria and endotoxin in meconium-stained amniotic fluid at term: could intra-amniotic infection cause meconium passage?

BACKGROUND

Meconium-stained amniotic fluid (MSAF) is a common occurrence among women in spontaneous labor at term, and has been associated with adverse outcomes in both mother and neonate. MSAF is a risk factor for microbial invasion of the amniotic cavity (MIAC) and preterm birth among women with preterm labor and intact membranes. We now report the frequency of MIAC and the presence of bacterial endotoxin in the amniotic fluid of patients with MSAF at term.

MATERIALS AND METHODS

We conducted a cross-sectional study including women in presumed preterm labor because of uncertain dates who underwent amniocentesis, and were later determined to be at term (n = 108). Patients were allocated into two groups: (1) MSAF (n = 66) and (2) clear amniotic fluid (n = 42). The presence of bacteria was determined by microbiologic techniques, and endotoxin was detected using the Limulus amebocyte lysate (LAL) gel clot assay. Statistical analyses were performed to test for normality and bivariate comparisons.

RESULTS

Bacteria were more frequently present in patients with MSAF compared to those with clear amniotic fluid [19.6% (13/66) versus 4.7% (2/42); p < 0.05]. The microorganisms were Gram-negative rods (n = 7), Ureaplasma urealyticum (n = 4), Gram-positive rods (n = 2) and Mycoplasma hominis (n = 1). The LAL gel clot assay was positive in 46.9% (31/66) of patients with MSAF, and in 4.7% (2/42) of those with clear amniotic fluid (p < 0.001). After heat treatment, the frequency of a positive LAL gel clot assay remained higher in the MSAF group [18.1% (12/66) versus 2.3% (1/42), p < 0.05]. Median amniotic fluid IL-6 concentration (ng/mL) was higher [1.3 (0.7-1.9) versus 0.6 (0.3-1.2), p = 0.04], and median amniotic fluid glucose concentration (mg/dL) was lower [6 (0-8.9) versus 9 (7.4-12.6), p < 0.001] in the MSAF group, than in those with clear amniotic fluid.

CONCLUSION

MSAF at term was associated with an increased incidence of MIAC. The index of suspicion for an infection-related process in postpartum women and their neonates should be increased in the presence of MSAF.

Infection and smoking are associated with decreased plasma concentration of the anti-aging protein, α-klotho

OBJECTIVE

The objective of this study was to determine whether maternal plasma concentrations of soluble α-klotho are different between women with microbial invasion of the intra-amniotic cavity (MIAC) and those without MIAC among preterm labor and intact membranes (PTL) or preterm prelabor rupture of membranes (pPROM).

METHODS

A cross-sectional study was conducted to include women in the following groups: i) PTL with MIAC (n=14); ii) PTL without MIAC (n=79); iii) pPROM with MIAC (n=30); and iv) pPROM without MIAC (n=33). MIAC was defined as a positive amniotic fluid culture for microorganisms (aerobic/anaerobic bacteria or genital mycoplasmas). Amniotic fluid samples were obtained within 48 h of maternal blood collection. Plasma concentration of soluble α-klotho was determined by ELISA.

RESULTS

i) The median plasma concentration (pg/mL) of soluble α-klotho was significantly lower in patients with MIAC than in those without MIAC (787.0 vs. 1117.8; P<0.001). ii) Among patients with PTL, those with MIAC had a lower median plasma concentration (pg/mL) of soluble α-klotho than those without MIAC (787.0 vs. 1138.9; P=0.007). iii) Among patients with pPROM, those with MIAC had a lower median plasma concentration (pg/mL) of soluble α-klotho than those without MIAC (766.4 vs. 1001.6; P=0.045). iv) There was no significant difference in the median plasma concentration of soluble α-klotho between PPROM without MIAC and PTL without MIAC (1001.6 pg/mL vs. 1138.9 pg/mL, respectively; P=0.5). v) After adjustment for potential confounders (maternal age, tobacco use, gestational age at venipuncture), soluble α-klotho remained significantly associated with MIAC (P=0.02); and vi) Among patients without MIAC, smoking was significantly associated with a lower median plasma concentration soluble α-klotho than in non-smokers (794.2 pg/mL vs. 1382.0 pg/mL, respectively; P<0.001); however, this difference was not observed in patients with MIAC.

CONCLUSIONS

Intra-amniotic infection occurring at preterm gestations (regardless of membrane status) was associated with a decrease in maternal plasma concentrations of soluble α-klotho. Moreover, among patients without infection, the plasma concentration of α-klotho was lower in smokers.

Matrix metalloproteinases-2, -3 and tissue inhibitors of metalloproteinases-1, -2 in placentas from preterm pregnancies and their association with one-carbon metabolites

Maternal nutrition is an important determinant of one-carbon metabolism and defects in the one-carbon metabolism may lead to poor obstetric outcomes. This study was designed to test the hypothesis that altered intake/metabolism of micronutrients (folic acid and vitamin B12) and docosahexaenoic acid (DHA) contributes to increased homocysteine and oxidative stress leading to altered levels of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) in women delivering preterm. We have earlier reported increased vitamin B12, homocysteine, and oxidative stress along with reduced placental DHA in women delivering preterm. In this study, we further examine the placental levels of MMP2, MMP3, TIMP1, and TIMP2 in 75 women delivering at term and 73 women delivering preterm. Placental levels of MMPs and TIMPs were determined by ELISA. Placental MMP2 and MMP3 levels were higher (P<0.01) in women delivering preterm as compared with term. There was no difference in the placental TIMP1 and TIMP2 levels in women delivering preterm and at term. Further placental MMP2 and MMP3 levels were higher (P<0.01) in women with preterm labor as compared with those in labor at term, suggesting that MMPs may favor degradation of extracellular matrix in the placenta during preterm labor. Our study for the first time suggests a crucial role of micronutrients and MMPs in preterm birth. Future studies need to examine if epigenetic modifications through the one-carbon cycle contribute to increased levels of MMPs leading to preterm deliveries.

Imbalances between matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinases (TIMPs) in maternal serum during preterm labor

BACKGROUND

Matrix metalloproteinases (MMPs) are involved in remodeling of the extracellular matrix (ECM) during pregnancy and parturition. Aberrant ECM degradation by MMPs or an imbalance between MMPs and their tissue inhibitors (TIMPs) have been implicated in the pathogenesis of preterm labor, however few studies have investigated MMPs or TIMPs in maternal serum. Therefore, the purpose of this study was to determine serum concentrations of MMP-3, MMP-9 and all four TIMPs as well as MMP:TIMP ratios during term and preterm labor.

METHODS

A case control study with 166 singleton pregnancies, divided into four groups: (1) women with preterm birth, delivering before 34 weeks (PTB); (2) gestational age (GA) matched controls, not in preterm labor; (3) women at term in labor and (4) at term not in labor. MMP and TIMP concentrations were measured using Luminex technology.

RESULTS

MMP-9 and TIMP-4 concentrations were higher in women with PTB vs. GA matched controls (resp. p = 0.01 and p<0.001). An increase in MMP-9:TIMP-1 and MMP-9:TIMP-2 ratio was observed in women with PTB compared to GA matched controls (resp. p = 0.02 and p<0.001) as well as compared to women at term in labor (resp. p = 0.006 and p<0.001). Multiple regression results with groups recoded as three key covariates showed significantly higher MMP-9 concentrations, higher MMP-9:TIMP-1 and MMP-9:TIMP-2 ratios and lower TIMP-1 and -2 concentrations for preterm labor. Significantly higher MMP-9 and TIMP-4 concentrations and MMP-9:TIMP-2 ratios were observed for labor.

CONCLUSIONS

Serum MMP-9:TIMP-1 and MMP-9:TIMP-2 balances are tilting in favor of gelatinolysis during preterm labor. TIMP-1 and -2 concentrations were lower in preterm gestation, irrespective of labor, while TIMP-4 concentrations were raised in labor. These observations suggest that aberrant serum expression of MMP:TIMP ratios and TIMPs reflect pregnancy and labor status, providing a far less invasive method to determine enzymes essential in ECM remodeling during pregnancy and parturition.

The clinical significance of a positive Amnisure test in women with preterm labor and intact membranes

OBJECTIVE

This study was conducted to examine the frequency and clinical significance of a positive Amnisure test in patients with preterm labor and intact membranes by sterile speculum exam.

STUDY DESIGN

A retrospective cohort study was performed including 90 patients with preterm labor and intact membranes who underwent Amnisure tests prior to amniocentesis (< 72 h); most patients (n=64) also underwent fetal fibronectin (fFN) tests. Amniotic fluid (AF) was cultured for aerobic/anaerobic bacteria and genital mycoplasmas and assayed for matrix metalloproteinase-8.

RESULTS

(1) the prevalence of a positive Amnisure test was 19% (17/90); (2) patients with a positive Amnisure test had significantly higher rates of adverse pregnancy and neonatal outcomes (e.g., impending preterm delivery, intra-amniotic infection/inflammation, and neonatal morbidity) than those with a negative Amnisure test; (3) a positive test was associated with significantly increased risk of intra-amniotic infection and/or inflammation, delivery within 7, 14, or 28 days and spontaneous preterm birth (< 35 weeks) among patients with a negative fFN test.

CONCLUSIONS

A positive Amnisure test in patients with preterm labor and intact membranes is a risk factor for adverse pregnancy outcome, particularly in patients with a negative fFN test. A positive Amnisure test in patients without symptoms or signs of ROM should not be taken as an indicator that membranes have ruptured.

Blood pH and gases in fetuses in preterm labor with and without systemic inflammatory response syndrome

OBJECTIVE

Fetal hypoxemia has been proposed to be one of the mechanisms of preterm labor (PTL) and delivery. This may have clinical implications since it may alter: (i) the method/frequency of fetal surveillance and (ii) the indications and duration of tocolysis to an already compromised fetus. The aim of this study was to examine whether there is a difference in the fetal blood gas analysis [pH, PaO(2) and base excess (BE)] and in the prevalence of fetal acidemia and hypoxia between: (i) patients in PTL who delivered within 72 hours vs. those who delivered more than 72 hours after cordocentesis and (ii) patients with fetal inflammatory response syndrome (FIRS) vs. those without this condition.

STUDY DESIGN

Patients admitted with PTL underwent amniocentesis and cordocentesis. Ninety women with singleton pregnancies and PTL were classified according to (i) those who delivered within 72 hours (n = 30) and after 72 hours of the cordocentesis (n = 60) and (ii) with and without FIRS. FIRS was defined as a fetal plasma concentration of IL-6 > 11 pg/mL. Fetal blood gases were determined. Acidemia and hypoxemia were defined as fetal pH and PaO(2) below the 5th percentile for gestational age, respectively. For comparisons between the two study groups, ΔpH and ΔPaO(2) were calculated by adjusting for gestational age (Δ = observed value - mean for gestational age). Non-parametric statistics were employed.

RESULTS

No differences in the median Δ pH (-0.026 vs. -0.016), ΔPaO(2) (0.25 mmHg vs. 5.9 mmHg) or BE (-2.4 vs. -2.6 mEq/L) were found between patients with PTL who delivered within 72 hours and those who delivered 72 hours after the cordocentesis (p > 0.05 for all comparisons). Fetal plasma IL-6 concentration was determined in 63% (57/90) of fetuses and the prevalence of FIRS was 28% (16/57). There was no difference in fetal pH, PaO(2) and BE between fetuses with and without FIRS (p > 0.05 for all comparisons). Moreover, there was no difference in the rate of fetal acidemia between fetuses with and without FIRS (6.3 vs. 9.8%; p > 0.05) and fetal hypoxia between fetuses with or without FIRS (12.5 vs. 19.5%; p > 0.05).

CONCLUSIONS

Our data do not support a role for acute fetal hypoxemia and metabolic acidemia in the etiology of PTL and delivery.

Midtrimester amniotic fluid concentrations of interleukin-6 and interferon-gamma-inducible protein-10: evidence for heterogeneity of intra-amniotic inflammation and associations with spontaneous early (<32 weeks) and late (>32 weeks) preterm delivery

INTRODUCTION

Intra-amniotic inflammation is traditionally defined as an elevation of amniotic fluid interleukin (IL)-6. Previous case control studies have suggested an association between an elevated midtrimester amniotic fluid IL-6 and preterm delivery, although such an association has been recently challenged. Intra-amniotic inflammation can also be defined by an elevation of the T-cell chemokine, Interferon-gamma-inducible protein (IP)-10. An elevation in amniotic fluid IP-10 has been associated with chronic chorioamnionitis, a lesion frequently found in late spontaneous preterm birth and fetal death. In contrast, an elevation in amniotic fluid IL-6 is typically associated with acute chorioamnionitis and funisitis. This study was conducted to examine the relationship between an elevation in amniotic fluid IL-6 in the midtrimester and preterm delivery at or before 32 weeks of gestation, and the amniotic fluid concentration of IP-10 and preterm delivery after 32 weeks of gestation.

MATERIALS AND METHODS

This cohort study included 847 consecutive women undergoing genetic midtrimester amniocentesis; in 796 cases, amniotic fluid and pregnancy outcome was available for study after exclusion of abnormal karyotype and/or fetal congenital anomalies. Spontaneous preterm delivery was defined as early (≤32 weeks) or late (after 32 completed weeks of pregnancy). The amniotic fluid and maternal blood concentrations of IL-6 and IP-10 were measured by specific immunoassays.

RESULTS

1) The prevalence of preterm delivery was 8.3% (66/796), while those of early and late spontaneous preterm delivery were 1.5% (n=12), and 4.5% (n=36), respectively; 2) patients who had a spontaneous preterm delivery after 32 weeks of gestation had a higher median amniotic fluid IP-10 concentration than those who delivered at term [median 713 pg/mL, inter-quartile range (IQR) 509-1427 pg/mL vs. median 589 pg/mL, IQR 402-953 pg/mL; P=0.006] and an elevation of amniotic fluid IP-10 concentration above 502 pg/mL (derived from an ROC curve) was associated with late spontaneous preterm delivery [odds ratio 3.9 (95% CI 1.6-9.9)]; 3) patients who had a spontaneous preterm delivery ≤32 weeks of gestation had a higher median amniotic fluid IL-6 concentration than those who delivered at term [median 2052 pg/mL, IQR 435-3015 pg/mL vs. median 414 pg/mL, IQR 209-930 pg/mL; P=0.006], and an elevated amniotic fluid IL-6 concentration above 1740 pg/mL (derived from an ROC curve) was associated with early spontaneous preterm delivery [odds ratio 9.5 (95% CI 2.9-31.1)]; 4) subclinical intra-amniotic inflammation, defined as an elevation of IL-6 (≥2.9 ng/mL) or IP-10 (≥2.2 ng/mL) concentration above the 95th percentile of patients who had uncomplicated term delivery (n=652 for IL-6 and n=633 for IP-10), was observed in 6.3% (50/796) and 5.8% (45/770) of cases, respectively. Although each type of inflammation is a risk factor for spontaneous preterm delivery, many patients had a term delivery without complication; 5) the amniotic fluid in the midtrimester did not contain microorganisms detectable with cultivation techniques.

CONCLUSIONS

INTRA-amniotic inflammation is heterogeneous. Some patients have elevated amniotic fluid concentrations of IL-6, and are at risk for spontaneous preterm delivery before 32 weeks of gestation, while others have an elevated IP-10 (a chemotactic T-cell chemokine) and such patients are at risk for spontaneous preterm delivery after 32 weeks of gestation. A fraction of patients have subclinical intra-amniotic inflammation and deliver at term. The clinical significance of this condition remains to be determined.

Hematologic profile of the fetus with systemic inflammatory response syndrome

OBJECTIVE

The fetal inflammatory response syndrome (FIRS) is associated with impending onset of preterm labor/delivery, microbial invasion of the amniotic cavity and increased perinatal morbidity. FIRS has been defined by an elevated fetal plasma interleukin (IL)-6, a cytokine with potent effects on the differentiation and proliferation of hematopoietic precursors. The objective of this study was to characterize the hematologic profile of fetuses with FIRS.

STUDY DESIGN

Fetal blood sampling was performed in patients with preterm prelabor rupture of membranes and preterm labor with intact membranes (n=152). A fetal plasma IL-6 concentration ≥ 11 pg/mL was used to define FIRS. Hemoglobin concentration, platelet count, total white blood cell (WBC) count, differential count, and nucleated red blood cell (NRBC) count were obtained. Since blood cell count varies with gestational age, the observed values were corrected for fetal age by calculating a ratio between the observed and expected mean value for gestational age.

RESULTS

1) The prevalence of FIRS was 28.9% (44/152); 2) fetuses with FIRS had a higher median corrected WBC and corrected neutrophil count than those without FIRS (WBC: median 1.4, range 0.3-5.6, vs. median 1.1, range 0.4-2.9, P=0.001; neutrophils: median 3.6, range 0.1-57.5, vs. median 1.8, range 0.2-13.9, P<0.001); 3) neutrophilia (defined as a neutrophil count >95th centile of gestational age) was significantly more common in fetuses with FIRS than in those without FIRS (71%, 30/42, vs. 35%, 37/105; P<0.001); 4) more than two-thirds of fetuses with FIRS had neutrophilia, whereas neutropenia was present in only 4.8% (2/42); 5) FIRS was not associated with detectable changes in hemoglobin concentration, platelet, lymphocyte, monocyte, basophil or eosinophil counts; and 6) fetuses with FIRS had a median corrected NRBC count higher than those without FIRS. However, the difference did not reach statistical significance (NRBC median 0.07, range 0-1.3, vs. median 0.04, range 0-2.3, P=0.06).

CONCLUSION

The hematologic profile of the human fetus with FIRS is characterized by significant changes in the total WBC and neutrophil counts. The NRBC count in fetuses with FIRS tends to be higher than fetuses without FIRS.

Bleeding per vaginam is associated with funisitis in women with preterm prelabour rupture of the fetal membranes

OBJECTIVE

To evaluate the risk of funisitis among women with preterm prelabour rupture of the membranes (PPROM) and subsequent bleeding per vaginam.

DESIGN

Prospective cohort study.

SETTING

A University Hospital in the USA.

POPULATION

A total of 157 women with PPROM, divided into those with bleeding per vaginam during the hospital admission (n = 46) and those without bleeding per vaginam (n = 111).

METHODS

Pathologist blinded to bleeding status assessed placental pathology for funisitis.

MAIN OUTCOME MEASURES

Funisitis.

RESULTS

Women with bleeding per vaginam were more likely to have funisitis (67.4% versus 36%, P < 0.001) compared with those without bleeding. Logistic regression demonstrated that bleeding per vaginam predicted funisitis after controlling for gestational age at admission, latency period and gestational age at delivery.

CONCLUSIONS

Among women with PPROM, those with bleeding per vaginam are more likely to have funisitis than those without bleeding per vaginam.

Evidence in support of a role for anti-angiogenic factors in preterm prelabor rupture of membranes

OBJECTIVE

Vaginal bleeding, placental abruption, and defective placentation are frequently observed in patients with preterm prelabor rupture of membranes (PROM). Recently, a role of vascular endothelial growth factor (VEGF) and its receptor, VEGF receptor (VEGFR)- 1 has been implicated in the mechanisms of membrane rupture. The purpose of this study was to determine whether the soluble form of VEGFR-1 and -2 concentrations in amniotic fluid (AF) change with preterm PROM, intra-amniotic infection/inflammation (IAI), or parturition.

STUDY DESIGN

This cross-sectional study included 544 patients in the following groups: (1) midtrimester (MT) (n = 48); (2) preterm labor (PTL) leading to term delivery (n = 143); (3) PTL resulting in preterm delivery with (n = 72) and without IAI (n = 100); (4) preterm PROM with (n = 46) and without IAI (n = 42); (5) term in labor (n = 48); and (6) term not in labor (n = 45). The concentrations of sVEGFR-1 and sVEGFR-2 were determined by ELISA. Non-parametric statistics and logistic regression analysis were applied.

RESULTS

(1) Preterm PROM (with and without IAI) had a lower median AF concentration of sVEGFR-1 than patients with PTL who delivered at term (p < 0.001 for each comparison); (2) A decrease in AFsVEGFR-1 concentrations per each quartile was associated with PROM after adjusting for confounders (OR 1.8; 95%CI 1.4-2.3); (3) IAI, regardless of the membrane status, was not associated with a change in the median AF concentrations of sVEGFR-1 and sVEGFR-2 (p > 0.05 for each comparison); and (4) Spontaneous term and PTL did not change the median sVEGFR-1 and sVEGFR-2 concentrations (p > 0.05 for each comparison).

CONCLUSION

(1) This is the first evidence that preterm PROM is associated with a lower AF concentration of sVEGFR-1 than patients with PTL intact membranes. These findings cannot be attributed to gestational age, labor, or IAI; and (2) AF concentrations of sVEGFR-2 did not change with preterm PROM, IAI, or labor at term and preterm.

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.

Circulating levels of matrix proteases and their inhibitors in pregnant women with and without a history of recurrent pregnancy loss

BACKGROUND

We have recently shown that serum relaxin-2 levels are attenuated in women with a history of recurrent pregnancy loss (RPL). We sought to determine whether a history of RPL is also associated with changes in serum matrix metalloproteases (MMPs) and tissue inhibitors of matrix metalloproteases (TIMP) -1 and -2.

METHODS

We obtained serum from 20 pregnant women with a history of RPL and 20 age-matched pregnant women with no history of RPL (NRPL) at 6-8, 10-12, 20, and 34 weeks gestation, and from cord blood. We quantified total serum concentrations of MMP-1, MMP-3, MMP-9 and TIMP-1 and TIMP-2 by ELISA. We determined whether these serum marker levels were associated with a history of RPL and delivery before 37 weeks gestation.

RESULTS

There was no difference in the rates of miscarriage, preterm birth or prelabour rupture of fetal membranes between RPL and NRPL. However babies born to RPL were lighter than those born to NRPL. Serum MMP-1, 9, and TIMP-1 did not differ between RPL and NRPL but MMP-3 was higher in RPL vs. NRPL at 6-8 weeks (P < 0.05). Serum TIMP-2 levels were higher in RPL women at all gestations (P < 0.01). The ratio of RLX-2 (reported previously) to TIMP-2 at 10-12 weeks gestation was more strongly associated with a history of RPL than either peptide separately - area under the ROC curves for RLX-2 0.79 (95% CI 0.57 to 0.92), TIMP-2 0.83 (95% CI 0.63 to 0.95), and for RLX-2:TIMP-2 ratio 0.92 (95% CI 0.74 to 0.99).

CONCLUSIONS

Women with a history of RPL demonstrate increased serum TIMP-2 and reduced RLX-2 during a subsequent viable pregnancy. Determination of both markers in early pregnancy enhances the discrimination of women with a history of RPL. These observations suggest roles for these two peptides in early implantation and placental development. Whether these may prove to be reliable early predictive markers for subsequent pregnancy loss in the index pregnancy is unknown and will require further studies.

Characterization of the transcriptome of chorioamniotic membranes at the site of rupture in spontaneous labor at term

OBJECTIVE

The purpose of this study was to compare the transcriptome between the site of membrane rupture and the chorioamniotic membranes away from the site of rupture.

STUDY DESIGN

The transcriptome of amnion and chorion (n=20 each) from and distal to the site of rupture from women with spontaneous labor and vaginal delivery at term after spontaneous rupture of membranes was profiled with Illumina HumanHT-12 microarrays. Selected genes were validated with the use of quantitative reverse transcription-polymerase chain reaction.

RESULTS

Six hundred seventy-seven genes were differentially expressed in the chorion between the rupture and nonrupture sites (false discovery rate<0.1; fold change>1.5). Quantitative reverse transcription-polymerase chain reaction confirmed the differential expression in 10 of 14 genes. Enriched biological processes included anatomic structure development, cell adhesion and signal transduction. Extracellular matrix-receptor interaction was the most impacted signaling pathway.

CONCLUSION

The transcriptome of fetal membranes after spontaneous rupture of membranes in term labor is characterized by region- and tissue-specific differential expression of genes that are involved in signature pathways, which include extracellular matrix-receptor interactions.

SAR150640, a selective beta3-adrenoceptor agonist, prevents human myometrial remodelling and activation of matrix metalloproteinase in an in vitro model of chorioamnionitis

BACKGROUND AND PURPOSE

The uterine pathophysiology underlying inflammatory conditions such as chorioamnionitis remains largely unclear. As we have shown that beta(3)-adrenoceptors act as regulators of myometrial inflammation, we wanted to investigate the potential role of beta(3)-adrenoceptors in preventing uterine remodelling induced by inflammation.

EXPERIMENTAL APPROACH

The consequences of human chorioamnionitis on myometrial remodelling were characterized by Sirius Red staining and metalloproteinase (MMP) expression, and compared with the effects of incubating human myometrial samples with Escherichia coli lipopolysaccharide (LPS) in vitro. We also assessed the effect of SAR150640, a selective beta(3)-adrenoceptor agonist, on the production and activity of MMPs.

KEY RESULTS

Chorioamnionitis was associated with a 46% decrease in total collagen, as well as over-expression of MMP2 (+61%) and MMP9 (+84%); both effects were reproduced by incubation with LPS (10 microg x mL(-1), 48 h). LPS-induced over-expression of MMP2 and MMP9 in normal human myometrium was paralleled by an overactivity of the proteins. Both over-expression and overactivity were prevented by the beta(3)-adrenoceptor agonist SAR150640 in a concentration-dependent manner. SAR150640, by itself, did not exhibit any effect on MMP production in control tissues.

CONCLUSIONS AND IMPLICATIONS

This study shows that inflammation was associated with an intense remodelling of human myometrium, a process likely to be explained by MMP activation. Our study emphasizes the potential therapeutic relevance of beta(3)-adrenoceptor agonists to the treatment of preterm labour and other uterine inflammatory conditions.

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.

The concentration of surfactant protein-A in amniotic fluid decreases in spontaneous human parturition at term

OBJECTIVE

The fetus is thought to play a central role in the onset of labor. Pulmonary surfactant protein (SP)-A, secreted by the maturing fetal lung, has been implicated in the mechanisms initiating parturition in mice. The present study was conducted to determine whether amniotic fluid concentrations of SP-A and SP-B change during human parturition.

STUDY DESIGN

Amniotic fluid SP-A and SP-B concentrations were measured with a sensitive and specific ELISA in the following groups of pregnant women: (1) mid-trimester of pregnancy, between 15 and 18 weeks of gestation (n = 29), (2) term pregnancy not in labor (n = 28), and (3) term pregnancy in spontaneous labor (n = 26). Non-parametric statistics were used for analysis.

RESULTS

SP-A was detected in all amniotic fluid samples. SP-B was detected in 24.1% (7/29) of mid-trimester samples and in all samples at term. The median amniotic fluid concentrations of SP-A and SP-B were significantly higher in women at term than in women in the mid-trimester (SP-A term no labor: median 5.6 microg/mL, range 2.2-15.2 microg/mL vs. mid-trimester: median 1.64 microg/mL, range 0.1-4.7 microg/mL, and SP-B term no labor: median 0.54 microg/mL, range 0.17-1.99 microg/mL vs. mid-trimester: median 0 microg/mL, range 0-0.35 microg/mL; both p < 0.001). The median amniotic fluid SP-A concentration in women at term in labor was significantly lower than that in women at term not in labor (term in labor: median 2.7 microg/mL, range 1.2-10.1 microg/mL vs. term no labor: median 5.6 microg/mL, range 2.2-15.2 microg/mL; p < 0.001). There was no significant difference in the median amniotic fluid SP-B concentrations between women in labor and those not in labor (term in labor: median 0.47 microg/mL, range 0.04-1.32 microg/mL vs. term no labor: median 0.54 microg/mL, range 0.17-1.99 microg/mL; p = 0.2).

CONCLUSION

The amniotic fluid concentration of SP-A decreases in spontaneous human parturition at term.

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.

Evidence supporting proteolytic cleavage of insulin-like growth factor binding protein-1 (IGFBP-1) protein in amniotic fluid

OBJECTIVE

The purpose of this study was to determine if: 1) insulin-like growth factor binding protein-1 (IGFBP-1) in amniotic fluid (AF) exhibited proteolytic cleavage in cases of intra-amniotic inflammation; and 2) if the matrix metalloproteinases (MMP-3, MMP-8, MMP-9) in AF are associated with the degradation of IGFBP-1 in AF.

METHODS

AF samples (n=20) were obtained from preterm gestations with and without intra-amniotic inflammation. The form of IGFBP-1 in AF was assessed by Western blot analysis and AF MMP-8 concentration was measured by ELISA. Densitometric analysis of Western blot was performed and the fragmented/intact IGFBP-1 ratio was calculated. Proteolysis of AF IGFBP-1 by MMPs was evaluated by incubating AF with exogenous human MMP-3, MMP-8 or MMP-9, and by incubating recombinant human IGFBP-1 in AF with and without inflammation.

RESULTS

1) IGFBP-1 was present in AF without inflammation as an intact form; however, the fragmented form was dominant in AF with inflammation; 2) the ratio of fragmented/intact IGFBP-1 was significantly higher in AF with inflammation than in AF without inflammation; 3) a higher ratio of fragmented/intact IGFBP-1 was associated with a higher concentration of MMP-8; 4) in-vitro proteolysis experiments showed that AF IGFBP-1 was degraded by exogenous human MMP-3, MMP-8 and MMP-9; 5) recombinant human IGFBP-1 was fragmented in AF with inflammation, but not in AF without inflammation.

CONCLUSION

The fragmented form of AF IGFBP-1 was significantly increased in AF with intra-amniotic inflammation, and MMPs produced in AF with intra-amniotic inflammation were associated with the proteolytic change of AF IGFBP-1.

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.

Recurrent preterm birth

Recurrent preterm birth is frequently defined as two or more deliveries before 37 completed weeks of gestation. The recurrence rate varies as a function of the antecedent for preterm birth: spontaneous versus indicated. Spontaneous preterm birth is the result of either preterm labor with intact membranes or preterm prelabor rupture of the membranes. This article reviews the body of literature describing the risk of recurrence of spontaneous and indicated preterm birth. Also discussed are the factors which modify the risk for recurrent spontaneous preterm birth (a short sonographic cervical length and a positive cervicovaginal fetal fibronectin test). Patients with a history of an indicated preterm birth are at risk not only for recurrence of this subtype, but also for spontaneous preterm birth. Individuals of black origin have a higher rate of recurrent preterm birth.

The effect of a matrix metalloproteinase inhibitor on inflammation-mediated preterm delivery

OBJECTIVE

Several matrix metalloproteinases (MMP) have been implicated in preterm parturition. We hypothesized that administration of a MMP inhibitor would reduce the rate of inflammation-mediated preterm delivery and prolong gestation in a mouse model.

STUDY DESIGN

We utilized an animal model of endotoxin-induced preterm delivery using timed pregnant C57Bl6 mice. Test animals received lipopolysaccharide (LPS) followed by the MMP inhibitor at 1 dose 12 hours after the LPS. Control mice received the same dose of LPS, followed by a control solution 12 hours after the LPS. The primary outcome was preterm delivery rate.

RESULTS

Mice in the study group had a significantly lower rate of preterm delivery (44%) compared to 100% in the controls (P = .009). Furthermore, the latency between the administration of injection and delivery was also longer in the study group (means 28.3 hours, standard deviation 9.4 hours) than among controls (mean 15.7 hours, standard deviation 1.8 hours) (P < .001).

CONCLUSION

Administration of an MMP inhibitor results in a decreased rate of inflammation-mediated preterm delivery in this animal model.

Pre-term delivery and periodontal disease: a case?control study from Croatia

AIM

The aim of this report was to assess the strength and influence of periodontitis as a possible risk factor for pre-term birth (PTB) in a cohort of 81 primiparous Croatian mothers aged 18-39 years.

METHODS

PTB cases (n = 17; mean age 25 +/- 2.9 years; age range 20-33 years) were defined as spontaneous delivery after less than 37 completed weeks of gestation that were followed by spontaneous labour or spontaneous rupture of membranes. Controls (full-time births) were normal births at or after 37 weeks of gestation (n = 64; mean age 25 +/- 2.9 years; age range 19-39 years). Information on known risk factors and obstetric factors included the current pregnancy history, maternal age at delivery, pre-natal care, nutritional status, tobacco use, alcohol use, genitourinary infections, vaginosis, gestational age, and birth weight. Full-mouth periodontal examination was performed on all mothers within 2 days of delivery.

RESULTS

PTB cases had significantly worse periodontal status than controls (p = 0.008). Multivariate logistic regression model, after controlling for other risk factors, demonstrated that periodontal disease is a significant independent risk factor for PTB, with an adjusted odds ratio of 8.13 for the PTB group (95% confidence interval 2.73-45.9).

CONCLUSION

Periodontal disease represents a strong, independent, and clinically significant risk factor for PTB in the studied cohort. There are strong indicators that periodontal therapy should form a part of preventive prenatal care in Croatia.

Can levels of interleukins and matrix metalloproteinases in the amniotic fluid predict postnatal bowel function in fetuses with gastroschisis?

PURPOSE

The aim of this study was to determine whether interleukin or matrix metalloproteinase (MMP) levels in the amniotic fluid can predict the postnatal condition of the bowel in fetuses with gastroschisis (GS).

METHODS

Eleven pregnant women with a fetus with GS underwent amniocentesis. Levels of IL-1alpha, IL-1beta, and IL-6 were measured in 10 of 11 specimens, and MMP-1, MMP-3, and MMP-8 levels were measured in 7 of 11 specimens. Neonates who tolerated complete oral feeding within 21 days were considered to have good bowel status (GS/good: n = 4, 4 in interleukin study or 3 in MMP study); those who did not were considered to have poor bowel status (GS/poor: n =7, 6 in interleukin study or 4 in MMP study). Seventy-eight women undergoing amniocentesis for other reasons served as controls.

RESULTS

Interleukin-1 levels were considerably lower in the pregnancies complicated by GS than in controls. Matrix metalloproteinases 3 and 8 levels were significantly higher in the GS pregnancies than in controls. Neonates with poor bowel status had higher MMP-3 and MMP-8 levels than those with good bowel status.

CONCLUSION

Amniotic fluid MMP-3 and MMP-8 levels may prove useful to assess the condition of the bowel in fetuses with GS.

The prevalence and clinical significance of amniotic fluid 'sludge' in patients with preterm labor and intact membranes

OBJECTIVE

To determine the prevalence and clinical significance of amniotic fluid (AF) 'sludge' observed during transvaginal ultrasound examination of the cervix in patients with preterm labor and intact membranes, and in those with uncomplicated pregnancies.

METHODS

This retrospective study included patients with preterm labor and intact membranes (n = 84) and those with uncomplicated term pregnancies (n = 298). The outcome variables included the occurrence of documented microbial invasion of the amniotic cavity (MIAC), histological chorioamnionitis, examination-to-delivery interval, admission to the neonatal intensive care unit (NICU), a composite neonatal morbidity, perinatal death, and delivery within 48 h, 7 days, and < 35 weeks and < 32 weeks. Statistical analysis included Chi-square test, stepwise logistic regression analysis and survival analysis.

RESULTS

The prevalence of AF 'sludge' was 1% (3/298) in patients with uncomplicated term pregnancies and 22.6% (19/84) in those with preterm labor and intact membranes. Among patients with preterm labor and intact membranes: (1) cervical length < or = 15 mm was present in 58.3% (49/84) of the patients; (2) the prevalence of MIAC and histological chorioamnionitis was 12.1% (7/58) and 32.9% (25/76), respectively; (3) the rate of spontaneous preterm delivery within 48 h, 7 days, and < 32 weeks and < 35 weeks of gestation was 13.6% (8/59), 28.8% (17/59), 39.5% (17/43) and 50.8% (30/59), respectively; (4) patients with AF 'sludge' had a higher frequency of positive AF cultures [33.3% (6/18) vs. 2.5% (1/40), P = 0.003] and histological chorioamnionitis [77.8% (14/18) vs. 19% (11/58), P < 0.001] than those without AF 'sludge'; (5) a higher proportion of neonates born to patients with AF 'sludge' was admitted to the NICU [64.3% (9/14) vs. 12.9% (8/62), P < 0.01], had a composite neonatal morbidity [36.8% (7/19) vs. 13.8% (9/65), P = 0.04] and died in the perinatal period [36.8% (7/19) vs. 4.6% (3/65), P = 0.001] than those born to women without 'sludge'; (6) a higher proportion of patients with AF 'sludge' had spontaneous delivery within 48 h [42.9% (6/14) vs. 4.4% (2/45), P = 0.001], within 7 days [71.4% (10/14) vs. 15.6% (7/45), P < 0.001], < 32 weeks [75% (9/12) vs. 25.8% (8/31), P = 0.005] and < 35 weeks [92.9% (13/14) vs. 37.8% (17/45), P < 0.001] than those without AF 'sludge'; and (7) patients with AF 'sludge' had a shorter examination-to-delivery interval than those without AF 'sludge' [AF 'sludge' median, 1 (IQR, 1-5) days vs. no AF 'sludge' median, 33 (IQR, 18-58) days; P < 0.001].

CONCLUSION

The presence of AF 'sludge' in patients with preterm labor and intact membranes is a risk factor for MIAC, histological chorioamnionitis and impending preterm delivery.