Collagenolytic enzymes (gelatinases) and their inhibitors in human amniochorionic membrane

Vaginal matrix metalloproteinase-9 (MMP-9) as a potential early predictor of preterm birth

OBJECTIVES

To evaluate the differences in vaginal matrix metalloproteinases (MMP) and tissue inhibitors of metalloproteinases (TIMPs) in pregnant patients with a history of prior preterm birth compared with controls.

METHODS

A prospective cohort pilot study recruited patients during prenatal care with history of prior spontaneous preterm birth (high-risk group) or no history of preterm birth (low-risk/controls). Inclusion criteria were singleton gestation at 11-16 weeks and between 18 and 55 years of age. Exclusion criteria were diabetes mellitus, hypertension, diseases affecting the immune response or acute vaginitis. A vaginal wash was performed at time of enrollment, and patients were followed through delivery. Samples were analyzed using semi-quantitative analysis of MMPS and TIMPS. The study was approved by the IRB and a p-value <0.05 was considered significant.

RESULTS

A total of 48 pregnant patients were recruited: 16 with a history of preterm birth (high-risk group) and 32 with no history of preterm birth (low-risk group/controls). Groups were similar in age, race, BMI, and delivery mode. The high-risk group had more multiparous women (100 vs. 68.8 %; p=0.02), a greater preterm birth rate (31.2 vs. 6.3 %; p=0.02), and a lower birth weight (2,885 ± 898 g vs. 3,480 ± 473 g; p=0.02). Levels of vaginal MMP-9 were greater in high-risk patients than low-risk patients (74.9 % ± 27.0 vs. 49.4 % ± 31.1; p=0.01). When dividing the cohort into patients that had a spontaneous preterm birth (7/48, 14.6 %) vs. those with a term delivery (41/48, 85.4 %), the vaginal MMP-9 remained elevated in the cohort that experienced a preterm birth (85.46 %+19.79 vs. 53.20 %+31.47; p=0.01). There were no differences in the other MMPS and in TIMPs between high and low-risk groups.

CONCLUSIONS

There was an increase in vaginal MMP-9 during early pregnancy in those at high risk for preterm birth and in those who delivered preterm, regardless of prior pregnancy outcome. Vaginal MMP-9 may have potential as a marker of increased risk of preterm birth.

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.

Transcriptomic analysis of the chorioallantois in equine premature placental separation

BACKGROUND

Equine premature placental separation (PPS) is poorly understood and represents an important risk factor for fetal/neonatal hypoxia.

OBJECTIVES

To examine transcriptomic changes in the chorioallantois (CA) from mares with clinical PPS compared to the CA from normal foaling mares. Differential gene expression was determined and gene ontology as well as molecular pathways related to PPS were characterised.

STUDY DESIGN

Retrospective case: control study.

METHODS

CA were collected from Thoroughbred mares with a clinical history of PPS (n=33) and from control Thoroughbred mares (n=4) with normal parturition for examination of transcriptional changes in the placenta associated with PPS. Transcriptomic changes in the villous CA near the cervical star were determined by Illumina® sequencing and subsequent bioinformatic analysis. PPS samples were divided by k-means clustering, and differentially expressed genes (DEGs) in each PPS cluster were identified by comparing to controls. Shared DEGs between PPS clusters were used for gene ontology analysis and pathway analysis.

RESULTS

A total of 1204 DEGs were identified between PPS and control. Gene ontology revealed extracellular matrix (ECM) and cell adhesion, and pathway analysis revealed fatty acid, p-53, hypoxia, and inflammation. Eleven key regulator genes of PPS including growth factors (IGF1, TGFB2, TGFB3), transcription factors (HIF1A, JUNB, SMAD3), and transmembrane receptors (FGFR1, TNFRSF1A, TYROBP) were also identified.

MAIN LIMITATIONS

The use of clinical history of PPS, in the absence of other criteria, may have led to misidentification of some cases as PPS.

CONCLUSIONS

Transcriptomic analysis indicated that changes in ECM and cell adhesion were important factors in equine PPS. Key predicted upstream events include genes associated with hypoxia, inflammation and growth factors related to the pathogenesis of equine PPS.

Chorioamnionitis has no impact on immunohistochemical expression of IL-6 in placental membranes of the late preterm delivery regardless of the membrane status

OBJECTIVES

To compare the immunohistochemical expression of IL-6 in placental membranes of late preterm delivery in women with histologically proven chorioamnionitis with and without preterm premature rupture of membranes (PPROM).

METHODS

Fetal membranes were collected from 60 women who had late preterm delivery with histologic chorioamnionitis with and without PPROM (30 in each group). Immunohistochemistry for IL-6 was performed on formalin fixed and paraffin-embedded sections. The two groups were matched for age, body mass index and parity. SPSS Version 17.0 was used for statistical analysis.

RESULTS

There was no difference in immunohistochemical expression of IL-6 in placental membranes of women with histologic chorioamnionitis regardless of the membrane status.

CONCLUSIONS

Chorioamnionitis has no impact on immunohistochemical expression of IL-6 in placental membranes of women with late preterm delivery despite the clinical presentation.

Why Do the Fetal Membranes Rupture Early after Fetoscopy? A Review

Iatrogenic preterm premature rupture of the fetal membranes (iPPROM) remains the Achilles' heel of keyhole fetal surgery (fetoscopy) despite significant efforts in preclinical models to develop new therapies. This limited success is partially due to incomplete understanding why the fetal membranes rupture early after fetoscopy and notable differences in membrane physiology between humans and domestic species. In this review, we summarize aspects of fetoscopy that may contribute to iPPROM, the previous efforts to develop new therapies, and limitations of preclinical models commonly used in fetal membrane research.

The short-chain fatty acids butyrate and propionate protect against inflammation-induced activation of mediators involved in active labor: implications for preterm birth

Spontaneous preterm birth is a global health issue affecting up to 20% of pregnancies and leaves a legacy of neurodevelopmental complications. Inflammation has been implicated in a significant proportion of preterm births, where pro-inflammatory insults trigger production of additional pro-inflammatory and pro-labor mediators. Thus, novel therapeutics that can target inflammation may be a novel avenue for preventing preterm birth and improving adverse fetal outcomes. Short-chain fatty acids (SCFAs), such as butyrate and propionate, are dietary metabolites produced by bacterial fermentation of fiber in the gut. SCFAs are known to possess anti-inflammatory properties and have been found to function through G-coupled-receptors and histone deacetylases. Therefore, this study aimed to investigate the effect of SCFAs on pro-inflammatory and pro-labor mediators in an in vitro model of preterm birth. Primary human cells isolated from myometrium and fetal membranes (decidua, amnion mesenchymal and amnion epithelial cells) were stimulated with the pro-inflammatory cytokines tumor necrosis factor alpha (TNF) or interleukin 1B (IL1B). The SCFAs butyrate and propionate suppressed inflammation-induced expression of pro-inflammatory cytokines and chemokines, adhesion molecules, the uterotonic prostaglandin PGF2alpha and enzymes involved in remodeling of myometrium and degradation of the fetal membranes. Notably, propionate and butyrate also suppressed inflammation-induced prostaglandin signaling and myometrial cell contraction. These effects appear to be mediated through suppression of nuclear factor kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) activation. These results suggest that the SCFAs may be able to prevent myometrial contractions and rupture of membranes. Further in vivo studies are warranted to identify the efficacy of SCFAs as a novel anti-inflammatory therapeutic to prevent inflammation-induced spontaneous preterm birth.

Targeting bromodomain-containing proteins to prevent spontaneous preterm birth

Preterm birth is a global healthcare challenge. Spontaneous preterm birth (sPTB) is commonly caused by inflammation, yet there are currently no effective therapies available. The Bromodomain and Extra-Terminal motif (BET) proteins, Bromodomain-containing protein (Brd) 2 (Brd2), Brd3 and Brd4 regulate inflammation in non-gestational tissues. The roles of Brd2-4 in human pregnancy are unknown. Using human and mouse models, the present study has identified the Brd proteins part of the process by which inflammation induces parturition. Using human clinical samples, we demonstrate that labor and infection increase the expression of Brds in the uterus and fetal membranes. In primary human myometrial, amnion and decidual cells, we found that global Brd protein inhibition, as well as selective inhibition of Brds, suppressed inflammation-induced expression of mediators involved in myometrial contractions and rupture of fetal membranes. Importantly, studies in the mouse model demonstrate that the pan-Brd inhibitor JQ1 reduced intrauterine inflammation induced by bacterial endotoxin LPS as well as decreasing the effectiveness of LPS to induce parturition. These results implicate BET proteins as novel therapeutic targets for reducing inflammation associated with spontaneous preterm labor.

Associations between second-trimester amniotic fluid levels of ADAMTS4, ADAMTS5, IL-6, and TNF-α and spontaneous preterm delivery in singleton pregnancies

Background We investigated the roles of inflammatory cytokines and the A disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) family in the etiopathogenesis of spontaneous preterm delivery by comparing the ADAMTS4, ADAMTS5, interleukin (IL)-6, and tumor necrosis factor-α (TNF-α) levels in second-trimester amniotic fluid between pregnant women with preterm birth and term controls. Methods All pregnant women who underwent second-trimester amniocentesis for genetic analysis between January 1, 2016, and January 1, 2018, were enrolled in this study. From this cohort, 22 patients who subsequently experienced spontaneous preterm delivery before 34 weeks of pregnancy formed the study group, and 22 age- and body mass index (BMI)-matched patients without preterm birth constituted the control group. Results No significant differences were observed between the preterm birth and control groups in terms of age, BMI, obstetric history of preterm delivery, gestational age at amniocentesis, or indication for amniocentesis. The mean amniotic fluid levels of ADAMTS4 and ADAMTS5 were significantly increased in the preterm birth group compared to the control group (248.3±22.6 and 182.4±19.8 pg/mL, P=0.012; and 198.6±21.6 and 159.1±21.7 pg/mL, P=0.035, respectively). Significantly increased IL-6 and TNF-α levels were also detected in the amniotic fluid of women who experienced spontaneous preterm delivery, relative to controls (142.1±16.2 and 95.8±16.4 pg/mL, P<0.001; and 139.4±12.5 and 89.6±11.2 pg/mL, P<0.001, respectively). Conclusion The results of this study imply that increased mid-trimester amniotic fluid levels of ADAMTS4, ADAMTS5, IL-6, and TNF-α play an important role in the pathophysiology of spontaneous preterm delivery.

Involvement of serum amyloid A1 in the rupture of fetal membranes through induction of collagen I degradation

The de novo synthesis of serum amyloid A1 (SAA1) is augmented in human fetal membranes at parturition. However, its role in parturition remains largely unknown. Here, we investigated whether SAA1 was involved in the rupture of fetal membranes, a crucial event in parturition accompanied with extensive degradation of collagens. Results showed that SAA1 decreased both intracellular and extracellular COL1A1 and COL1A2 abundance, the two subunits of collagen I, without affecting their mRNA levels in human amnion fibroblasts. These reductions were completely blocked only with inhibition of both matrix metalloproteases (MMPs) and autophagy. Consistently, SAA1 increased MMP-2/9 abundance and the markers for autophagic activation including autophagy related (ATG) 7 (ATG7) and the microtubule-associated protein light chain 3 β (LC3B) II/I ratio with the formation of LC3 punctas and autophagic vacuoles in the fibroblasts. Moreover, the autophagic degradation of COL1A1/COL1A2 and activation of MMP-2/9 by SAA1 were blocked by inhibitors for the toll-like receptors 2/4 (TLR2/4) or NF-κB. Finally, reciprocal corresponding changes of SAA1 and collagen I were observed in the amnion following spontaneous rupture of membranes (ROM) at parturition. Conclusively, SAA1 may participate in membrane rupture at parturition by degradating collagen I via both autophagic and MMP pathways. These effects of SAA1 appear to be mediated by the TLR2/4 receptors and the NF-κB pathway.

HMGB1-RAGE signaling pathway in pPROM

OBJECTIVE

Increased inflammation of the placenta is considered as a risk factor and a promoter of preterm premature rupture of the membranes (pPROM). High-mobility group box 1 (HMGB1) is a recently identified inflammatory cytokine, and HMGB1-RAGE signaling pathway has been associated with many pathophysiological processes. This study aims to reveal the mechanisms of HMGB1-RAGE signaling pathway in pPROM.

MATERIALS AND METHODS

The mRNA levels of relative gene of HMGB1 pathway, HMGB1, RAGE, NF-κBp65, MMP-9 and MMP-2, were analyzed by real-time PCR in placentas collected from 60 normal term women, 60 women with PROM and 60 women with pPROM. Additionally, levels of HMGB1, RAGE, NF-κBp65, MMP-9 and MMP-2 protein were detected in frozen placental specimens by western blot, and the locations of HMGB1, RAGE and NF-κBp65 were evaluated in the well-characterized tissue microarray (TMA) by immunohistochemistry. ELISA was further used to detect HMGB1, RAGE, NF-κBp65, MMP-9 and MMP-2 level in maternal and cord serum.

RESULTS

Compared with normal term and PROM women, we found that (1) The mRNA expressions of HMGB1, RAGE, NF-κBp65, MMP-9 and MMP-2 in HMGB1-RAGE pathway of pPROM placentas were higher. (2) The protein levels of HMGB1, RAGE, NF-κBp65, MMP-9 and MMP-2 in pPROM placentas were higher. (3) HMGB1 and RAGE immunoreactivity in pPROM placenta TMA were increased in the cytoplasm of syncytiotrophoblast (STB), extravillous trophoblast (EVT) and mesenchymal cells, while NF-κBp65 was enhanced in the nucleus of STB and EVT. (4) Maternal serum concentrations of HMGB1, RAGE, NF-κBp65, MMP-9 and MMP-2 in pPROM group were greater. (5) Cord serum concentrations of HMGB1, RAGE, NF-κBp65, MMP-9 and MMP-2 among the 3 groups had no significant differences.

CONCLUSION

HMGB1 nuclear-cytoplasmic translocation in pPROM placenta may lead to the binding of HMGB1 to its receptor RAGE, resulting in provoking NF-κBp65 activity, and then inducing the release of MMP-9 and MMP-2, which all above activities contributed to the process of pPROM. Consequently, HMGB1-RAGE signaling pathway may be involved in the pathogenesis of pPROM.

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.

Anti-inflammatory Elafin in human fetal membranes

OBJECTIVE

Elafin is a low molecular weight protein with antileukoproteinase, anti-inflammatory, antibacterial and immunomodulating properties. The profile of Elafin in fetal membranes is not well characterized. This study determined the changes in Elafin expression and concentration in human fetal membrane from patients with preterm prelabor rupture of membranes (PPROM) and in vitro in response to intra-amniotic polymicrobial pathogens.

METHOD

Elafin messenger RNA (mRNA) expressions were studied in fetal membranes from PPROM, normal term as well as in normal term not in labor membranes in an organ explant system treated (24 h) with lipopolysaccharide (LPS), using quantitative reverse transcription-polymerase chain reaction (RT-PCR). Enzyme-linked immunosorbent assay (ELISA) measured Elafin concentrations in culture supernatants from tissues treated with LPS and polybacterial combinations of heat-inactivated Mycoplasma hominis (MH), Ureaplasma urealyticum (UU) and Gardnerella vaginalis (GV).

RESULTS

Elafin mRNA expression in fetal membranes from women with PPROM was significantly higher compared to women who delivered at term after normal pregnancy (5.09±3.50 vs. 11.71±2.21; P<0.05). In vitro, LPS-stimulated membranes showed a significantly increased Elafin m-RNA expression (P<0.05). However, the protein levels after LPS stimulation was not changed. Similarly, polymicrobial-treated fetal membranes also showed no changes in Elafin protein concentrations compared to untreated controls.

CONCLUSION

Higher Elafin expression in PPROM fetal membranes suggests a host response to an inflammatory pathology. However, lack of Elafin response to LPS and polymicrobial treatment is indicative of the minimal anti-inflammatory impact of this molecule in fetal membranes.

Regulation of Matrix Metalloproteinases-2 and -9 Gene Expression in Cultured Human Fetal Membrane Cells by Influenza Virus Infection

In order to understand a possible etiology of adverse pregnancy outcomes associated with intrauterine influenza virus infection, we examined the effect of influenza virus infection on gene expression of matrix metalloproteinases (MMPs) in cultured amnion epithelial, amnion mesenchymal and chorion trophoblast cells prepared from human fetal membrane tissues by gelatin zymography, Western blotting and reverse transcriptase-PCR. The cells were infected with influenza A (H1N1) virus. The levels of pro-MMP-9 activity in culture supernatants of three types of cells were increased during the period of 24-48 h after the virus infection as compared to those of mock infection. Chorion trophoblast cells spontaneously released a much greater level of pro-MMP-2 activity than amnion epithelial and amnion mesenchymal cells. The cleavage of pro-MMP-2 into an active intermediate form was enhanced in chorion trophoblast cells by the virus infection. The activity levels of MMP-2 and MMP-9 in culture supernatants were consistent with their protein levels. The virus infection induced the mRNA expression of MMP-9, but not MMP-2, in three types of cells. These results suggest that influenza virus infection induces the gene expression of MMP-9 and the cleavage of pro-MMP-2 into an active intermediate form in human fetal membrane cells, resulting in weakening of the membranes through extracellular matrix degradation. Therefore, it is possible that the regulation of MMPs gene expression in fetal membrane cells by influenza virus infection is implicated in a part of the etiology of adverse pregnancy outcomes associated with intrauterine infection with the virus.

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.

Novel concepts on pregnancy clocks and alarms: redundancy and synergy in human parturition

The signals and mechanisms that synchronize the timing of human parturition remain a mystery and a better understanding of these processes is essential to avert adverse pregnancy outcomes. Although our insights into human labor initiation have been informed by studies in animal models, the timing of parturition relative to fetal maturation varies among viviparous species, indicative of phylogenetically different clocks and alarms; but what is clear is that important common pathways must converge to control the birth process. For example, in all species, parturition involves the transition of the myometrium from a relaxed to a highly excitable state, where the muscle rhythmically and forcefully contracts, softening the cervical extracellular matrix to allow distensibility and dilatation and thus a shearing of the fetal membranes to facilitate their rupture. We review a number of theories promulgated to explain how a variety of different timing mechanisms, including fetal membrane cell senescence, circadian endocrine clocks, and inflammatory and mechanical factors, are coordinated as initiators and effectors of parturition. Many of these factors have been independently described with a focus on specific tissue compartments.In this review, we put forth the core hypothesis that fetal membrane (amnion and chorion) senescence is the initiator of a coordinated, redundant signal cascade leading to parturition. Whether modified by oxidative stress or other factors, this process constitutes a counting device, i.e. a clock, that measures maturation of the fetal organ systems and the production of hormones and other soluble mediators (including alarmins) and that promotes inflammation and orchestrates an immune cascade to propagate signals across different uterine compartments. This mechanism in turn sensitizes decidual responsiveness and eventually promotes functional progesterone withdrawal in the myometrium, leading to increased myometrial cell contraction and the triggering of parturition. Linkage of these processes allows convergence and integration of the gestational clocks and alarms, prompting a timely and safe birth. In summary, we provide a comprehensive synthesis of the mediators that contribute to the timing of human labor. Integrating these concepts will provide a better understanding of human parturition and ultimately improve pregnancy outcomes.

The physiology of fetal membrane weakening and rupture: Insights gained from the determination of physical properties revisited

Rupture of the fetal membranes (FM) is precipitated by stretch forces acting upon biochemically mediated, pre-weakened tissue. Term FM develop a para-cervical weak zone, characterized by collagen remodeling and apoptosis, within which FM rupture is thought to initiate. Preterm FM also have a weak region but are stronger overall than term FM. Inflammation/infection and decidual bleeding/abruption are strongly associated with preterm premature FM rupture (pPROM), but the specific mechanisms causing FM weakening-rupture in pPROM are unknown. There are no animal models for study of FM weakening and rupture. Over a decade ago we developed equipment and methodology to test human FM strength and incorporated it into a FM explant system to create an in-vitro human FM weakening model system. Within this model TNF (modeling inflammation) and Thrombin (modeling bleeding) both weaken human FM with concomitant up regulation of MMP9 and cellular apoptosis, mimicking the characteristics of the spontaneous FM rupture site. The model has been enhanced so that test agents can be applied directionally to the choriodecidual side of the FM explant consistent with the in-vivo situation. With this enhanced system we have demonstrated that the pathways involving inflammation/TNF and bleeding/Thrombin induced FM weakening overlap. Furthermore GM-CSF production was demonstrated to be a critical common intermediate step in both the TNF and the Thrombin induced FM weakening pathways. This model system has also been used to test potential inhibitors of FM weakening and therefore pPROM. The dietary supplement α-lipoic acid and progestogens (P4, MPA and 17α-hydroxyprogesterone) have been shown to inhibit both TNF and Thrombin induced FM weakening. The progestogens act at multiple points by inhibiting both GM-CSF production and GM-CSF action. The use of a combined biomechanical/biochemical in-vitro human FM weakening model system has allowed the pathways of fetal membrane weakening to be delineated, and agents that may be of clinical use in inhibiting these pathways to be tested.

ADAMTS4 and Oxidative/Antioxidative Status in Preterm Premature Rupture of Membranes

AIM

To determine the function of a disintegrin and metalloproteinase with thrombospondin motifs-4 (ADAMTS4), total oxidant status (TOS), total antioxidant status (TAS), and aryl esterase (ARES) in preterm premature rupture of membranes (PPROM) and to investigate the association with premature rupture of membranes (PROMs).

MATERIAL AND METHODS

58 pregnant women were included in this prospective study which comprised 29 PPROM patients as the study group and 29 patients, having healthy amniotic membranes, as the control group. ADAMTS4, TAS, TOS, and ARES levels were studied in the amniotic membrane homogenates of the patients.

RESULTS

ADAMTS4, TAS TOS, and ARES levels of amniotic membrane lysates were significantly different between PPROM and control groups (p < 0.001, p < 0.001, p = 0.008 and p = 0.002, respectively). Increased amniotic membrane ADAMTS4 (OR: 1.051 95% CI 1.006-1.098, p = 0.024) and TOS (OR: 12.777 95% CI 1.595-102.323, p = 0.016) were found to be significantly associated with the increased risk of PPROM.

CONCLUSION

ADAMTS4, TOS, and ARES levels were higher and TAS level was lower in PPROM patients than the normal healthy control group which had healthy amniotic membranes at term. As a result, ADAMTS4 may have a role in the pathogenesis by causing increased oxidative and inflammatory environment in PPROM.

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.

Regulation of TIMP-1 in Human Placenta and Fetal Membranes by lipopolysaccharide and demethylating agent 5-aza-2'-deoxycytidine

BACKGROUND

An appropriate transcriptional profile in the placenta and fetal membranes is required for successful pregnancy; any variations may lead to inappropriate timing of birth. Epigenetic regulation through reversible modification of chromatin has emerged as a fundamental mechanism for the control of gene expression in a range of biological systems and can be modified by pharmacological intervention, thus providing novel therapeutic avenues. TIMP-1 is an endogenous inhibitor of MMPs, and hence is intimately involved in maintaining the integrity of the fetal membranes until labor.

OBJECTIVE AND METHODS

To determine if TIMP-1 is regulated by DNA methylation in gestational tissues we employed an in vitro model in which gestational tissue explants were treated with demethylating agent 5-aza-2'-deoxycytidine (AZA) and lipopolysaccharide (LPS).

RESULTS

Quantitative Real-Time PCR (qRT-PCR) revealed that TIMP-1 transcription was significantly increased by combined treatment of AZA and LPS, but not LPS alone, in villous, amnion and choriodecidua explants after 24 and 48 hrs, whilst western blotting showed protein production was stimulated after 24 hrs only. Upon interrogation of the TIMP-1 promoter using Sequenom EpiTyper MassARRAY, we discovered sex-specific differential methylation, in part explained by x-linked methylation in females. Increased TIMP-1 in the presence of LPS was potentiated by AZA treatment, signifying that a change in chromatin structure, but not in DNA methylation at the promoter region, is required for transcriptional activators to access the promoter region of TIMP-1.

CONCLUSIONS

Collectively, these observations support a potential role for pharmacological agents that modify chromatin structure to be utilized in the therapeutic targeting of TIMP-1 to prevent premature rupture of the fetal membranes in an infectious setting.

The role of chorionic cytotrophoblasts in the smooth chorion fusion with parietal decidua

BACKGROUND/PURPOSE

Human placenta and chorion are rapidly growing transient embryonic organs built from diverse cell populations that are of either, ectodermal [placenta and chorion specific trophoblast (TB) cells], or mesodermal origin [villous core and chorionic mesenchyme]. The development of placenta and chorion is synchronized from the earliest phase of implantation. Little is known about the formative stages of the human chorion, in particular the steps between the formation of a smooth chorion and its fusion with the parietal decidua.

METHODS

We examined the available histological material using immunohistochemistry, and further analyzed in vitro the characteristics of the recently established and reported human self-renewing trophoblast progenitor cells (TBPC) derived from chorionic mesoderm.

RESULTS

Here, we provided evidence that the mechanism by which smooth chorion fuses with parietal decidua is the invasion of smooth chorionic cytotrophoblasts (schCTBs) into the uterine wall opposite to the implantation side. This process, which partially replicates some of the mechanisms of the blastocyst implantation, leads to the formation of a new zone of contacts between fetal and maternal cells.

CONCLUSION

We propose the schCTBs invasion of the parietal decidua as a mechanism of 'fusion' of the membranes, and that schCTBs in vivo contribute to the pool of the invasive schCTB.

Chorioamniontis in preterm delivery is associated with degradation of decorin and biglycan and depletion of hyaluronan in fetal membranes

OBJECTIVE

The proteoglycan decorin stabilizes collagen whereas biglycan and hyaluronan disrupt well-organized collagen. The aim was to determine the concentrations of these constituents in fetal membranes in relation to gestational age, preterm labour, PPROM and chorioamnionitis.

STUDY DESIGN

Preterm fetal membranes (24-34 weeks gestation) were obtained from elective caesarean deliveries (N = 4), from PPROM (N = 14), and from preterm labour (N = 14). Term fetal membranes from elective caesarean deliveries (N = 9) and spontaneous vaginal deliveries (N = 11) were used for comparison. Chorioamnionitis was assessed histologically. The proteoglycans were analysed using alcian blue precipitation, SDS-PAGE and immunostaining. Hyaluronan was estimated by a radioimmunoassay.

RESULTS

Preterm amniotic membranes with chorioamnionitis displayed a 8-fold decrease in hyaluronan concentration as well as a pronounced (88%) degradation of decorin and biglycan (p < 0.05). The amnion from preterm elective caesarean sections had higher decorin (3.2 vs. 1.7 μg/mg, p < 0.05) and lower biglycan (0.4 vs. 1.0 μg/mg, p < 0.05) concentrations as compared to similar term amnion (p < 0.05), whereas the hyaluronan concentrations were not associated with gestational age. Also the chorio-decidua from preterm caesarean sections had higher decorin concentrations (1.8 vs. 1.0 μg/mg, p < 0.05) whereas the biglycan concentration was unchanged. Labour (term as well as preterm) was characterized by increased hyaluronan and biglycan concentrations in the amnion (not statistically significant).

CONCLUSION

The biglycan/decorin balance increases during third trimester of pregnancy and during active labour. This relation might contribute to mechanical weakening of the membranes. Chorioamnionitis induces dramatic degradation of both proteoglycans and hyaluronan, which can explain the decreased biomechanical strength.

The assessment of the relationship between amniotic fluid matrix metalloproteinase-9 and zinc levels with adverse obstetric outcomes

OBJECTIVE

To examine the relationship between the amniotic fluid MMP-9 and zinc levels during 16-19th gestational weeks and perinatal outcomes.

METHOD

One hundred and seventeen singleton pregnancies that underwent genetic amniocentesis from January 2005 through November 2009 were evaluated. Subjects were divided into two main groups: a control group (group 1) (n: 74), and an adverse obstetric outcomes group (group 2) (n: 43). Group 2 consisted of the following: preterm birth group, gestational hypertension and preeclampsia group, gestational diabetes group, fetal growth restriction group, macrosomia group, and pregnancy loss group. MMP-9 and zinc (Zn) values in the amniocentesis materials sampled between the 16th and 19th gestational weeks were analyzed retrospectively in terms of perinatal outcomes. Any significant difference among the groups was assessed by unpaired samples t test and the Mann-Whitney U test. Statistical significance was defined as p < 0.05.

RESULTS

A comparison among groups showed no significant difference in terms of Zn results between the group 1 and 2 (p = 0.879). MMP-9 levels were significantly lower in both the preterm birth group (p = 0.043) and group 1 (p = 0.015).

CONCLUSION

We found that the amniotic fluid MMP-9 levels of patients who delivered preterm were significantly lower between the 16th and 19th gestational weeks.

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.

Prolidase, matrix metalloproteinases 1 and 13 activity, oxidative-antioxidative status as a marker of preterm premature rupture of membranes and chorioamnionitis in maternal vaginal washing fluids

OBJECTIVE

Etiology of premature preterm rupture of membranes (PPROM) is not yet completely known and chorioamnionitis is one of the most important complications of its. We aimed to evaluate whether prolidase, matrix metalloproteinases, oxidative-antioxidative status, and inflammation markers in vaginal washing fluid (VWF) were associated with etiology of PPROM and whether these markers could be used to predict chorioamnionitis in PPROM.

STUDY DESIGN

This prospective case control study enrolled fifty pregnant women with PPROM and 50 healthy pregnant women. The VWF samples were taken at the time of admission in the PPROM group and patients were followed for chorioamnionitis. Prolidase, matrix metalloproteinases, oxidative-antioxidative status, and inflammation markers in VWF were assayed.

RESULTS

VWF levels of prolidase, matrix metalloproteinases 1-13 (p< 0.001), oxidative stress parameters, total oxidative stress (TOS) (p < 0.001) and oxidative stress index (OSI) (p = 0.002), and hs-CRP (p = 0.045) were significantly higher in the PPROM group than in the controls. Antioxidative status parameters, levels of paroxanase (PON-1) (p < 0.001) and total antioxidant capacity (TAC) (p < 0.001), were significantly lower in the PPROM group than in the controls. Mean VWF levels of prolidase (p < 0.001), metalloproteinases (p<0.05), and oxidative-antioxidative status parameters (p<0.05) were significantly different in women with versus women without chorioamnionitis in the PPROM group. Prolidase, MMP-13, TOS, TAC, and PON-1 were found as important predictors for chorioamnionitis in the PPROM group by the multivariate logistic regression analysis. When the ROC curve analysis for prolidase, MMP-13, TOS, TAC, and PON-1 were performed, all of them were statistically significant for area under the curve (areas under the curve were 0.94, 0.90, 0.80, 0.25, and 0.19, respectively).

CONCLUSIONS

This study showed that collagen turnover mediators, especially prolidase, and increased oxidative stress are significantly associated with PPROM. Also, chorioamnionitis can be predicted with prolidase, MMP-13, TOS, TAC, and PON-1 in PPROM patients.

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.

Maternal plasma prolidase, matrix metalloproteinases 1 and 13, and oxidative stress levels in pregnancies complicated by preterm premature rupture of the membranes and chorioamnionitis

OBJECTIVE

This study aimed to investigate the role of various biochemical markers in preterm premature rupture of membranes (PPROM) and in prediction of chorioamnionitis in patients with PPROM.

MATERIAL AND METHODS

This case-control study included a total of 100 pregnant women at 26-34 gestational weeks. Of these women, 50 were healthy and 50 had PPROM. The biochemical markers in the maternal plasma including prolidase, matrix metalloproteinase (MMP) 1 and 13, total oxidative status (TOS), total antioxidant capacity (TAC), glutathione peroxidase (GPx), catalase (CAT), paraoxonase-1 (PON-1), tumor necrosis factor alpha (TNF-α), and high sensitive C-reactive protein (hs-CRP) were assayed. These levels were compared between the PPROM and control groups and between women with or without chorioamnionitis in the PPROM group.

RESULTS

Compared to the control group, the levels of prolidase, MMP-13, and TOS were significantly higher (p values <0.001, 0.020, and 0.035, respectively) and those of TAC and PON-1 were significantly lower in the maternal plasma of the PPROM group (p values=0.012 and <0.001, respectively). The plasma prolidase and TOS levels were significantly higher (p values=0.033 and 0.005, respectively) and the plasma TAC and PON-1 levels were significantly lower in women with chorioamnionitis as compared with the corresponding values in women without chorioamnionitis in the PPROM group (p values =0.041 and 0.048, respectively). The multivariate logistic regression analysis observed that prolidase, TAC, and PON-1 were important markers for the presence of PPROM and prolidase and TOS were important markers for predicting chorioamnionitis.

CONCLUSION

This study suggested that maternal plasma prolidase, TAC, and PON-1 may be useful for the diagnosis of PPROM, and prolidase and TOS may be used to predict chorioamnionitis in patients with PPROM.

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.

Predictive value of intra-amniotic and serum markers for inflammatory lesions of preterm placenta

OBJECTIVE

To compare the relative predictive values of amniotic fluid (AF) matrix metalloproteinase-9 (MMP-9), interleukin-6 (IL-6), and serum C-reactive protein (CRP) for histologic chorioamnionitis and intra-amniotic infection in women with preterm labor or preterm premature rupture of membranes (PROM).

STUDY DESIGN

This retrospective cohort study included 99 consecutive women with preterm labor or preterm PROM (21-35 weeks' gestation) who delivered within 72 h of transabdominal amniocentesis. The AF was cultured for aerobic and anaerobic bacteria and for genital mycoplasmas and was assayed for MMP-9 and IL-6 levels. Maternal serum CRP was measured immediately after amniocentesis. The placentas were examined histologically.

MAIN OUTCOME MEASURES

histologic chorioamnionitis and intra-amniotic infection.

RESULTS

The prevalence of histologic chorioamnionitis and a positive AF culture was 44% (44/99) and 28% (28/99), respectively. In predicting intra-amniotic infection, AF MMP-9 had a significantly higher area under the curve (AUC: 0.94 [95% CI, 0.87-0.98]) than AF IL-6 (0.87 [95% CI, 0.78-0.84]; P < 0.05) and serum CRP (0.76 [95% CI, 0.66-0.84]; P < 0.001) and a higher sensitivity and specificity than serum CRP (P < 0.01, respectively). However, in predicting histologic chorioamnionitis, there were no significant differences in AUCs among the three tests (AF MMP-9: 0.78 [95% CI, 0.68-0.85]; AF IL-6: 0.76 [95% CI, 0.66-0.84]; serum CRP: 0.76 [95% CI, 0.66-0.84]). In a sub-analysis of 71 women without intra-amniotic infection, histologic chorioamnionitis was associated with an elevated serum CRP level (P < 0.05), but not with the level of AF IL-6 or MMP-9 (P = 0.232 and P = 0.402, respectively).

CONCLUSIONS

The AF MMP-9 has a better overall diagnostic performance than the AF IL-6 and maternal serum CRP in predicting intra-amniotic infection. However, the serum CRP level obtained up to 72 h before delivery appears to be an important marker for early identification of histologic chorioamnionitis in women without intra-amniotic infection.

In vitro secretion and activity profiles of matrix metalloproteinases, MMP-9 and MMP-2, in human term extra-placental membranes after exposure to Escherichia coli

BACKGROUND

Premature rupture of fetal membranes (PROM) complicated with intrauterine infection has been associated to alterations of the extracellular matrix (ECM) homeostasis. The aim of this work was to evaluate the integral/functional response of the amnion (AMN) and choriodecidua (CHD) to synthesis, secretion, and activity of MMP-2 and MMP-9 and of their inhibitors TIMP-1, -2, and -4, after stimulation with Escherichia coli.

METHODS

Full-thickness membranes were mounted on a Transwell device, constituting two independent chambers, Escherichia coli (1×10 (6) CFU/mL) were added to either the amniotic or the choriodecidual face or to both. Secretion profiles of MMP-2, MMP-9, TIMP-1, TIMP-2, and TIMP-4 were quantified by ELISA and gelatinolytic activity by zymography. Immunoreactivity for MMP-2 and MMP-9 was revealed by immunohistochemistry and the collagen content was assessed by the hydroxyproline assay.

RESULTS

Levels of MMP-9 in CHD and AMN increased 4- and 8-fold, respectively, after simultaneous infection. MMP-2 secreted to the medium by CHD increased a mean of 3 times after direct stimulation. Secretion profiles of TIMP-1, TIMP-2, and TIMP-4 remained without significant changes. Collagen content was significantly decreased (4-fold) in infected membranes, and was associated with loss of structural continuity and co-localization with immunoreactive forms of MMP-2 and MMP-9.

CONCLUSIONS

Infection of chorioamniotic membranes with E. coli induces an increase in the secretion of inactive forms and an association to ECM of active forms of MMP-2 and MMP-9 without changes in TIMP-1, -2, and -4. These changes could explain the significant decrease of collagen content and loss of structural continuity.

A genetic association study of maternal and fetal candidate genes that predispose to preterm prelabor rupture of membranes (PROM)

OBJECTIVE

We sought to determine whether maternal/fetal single-nucleotide polymorphisms (SNPs) in candidate genes are associated with preterm prelabor rupture of membranes (pPROM).

STUDY DESIGN

A case-control study was conducted in patients with pPROM (225 mothers and 155 fetuses) and 599 mothers and 628 fetuses with a normal pregnancy; 190 candidate genes and 775 SNPs were studied. Single locus/haplotype association analyses were performed; false discovery rate was used to correct for multiple testing (q* = 0.15).

RESULTS

First, a SNP in tissue inhibitor of metalloproteinase 2 in mothers was significantly associated with pPROM (odds ratio, 2.12; 95% confidence interval, 1.47-3.07; P = .000068), and this association remained significant after correction for multiple comparisons. Second, haplotypes for Alpha 3 type IV collagen isoform precursor in the mother were associated with pPROM (global P = .003). Third, multilocus analysis identified a 3-locus model, which included maternal SNPs in collagen type I alpha 2, defensin alpha 5 gene, and endothelin 1.

CONCLUSION

DNA variants in a maternal gene involved in extracellular matrix metabolism doubled the risk of pPROM.

Matrix metalloproteinases in the cervical mucus plug in relation to gestational age, plug compartment, and preterm labor

BACKGROUND

High concentrations of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) have been identified in the cervical mucus plug (CMP) at term of pregnancy. Their physiological and pathophysiological implications, however, remain to be elucidated, and CMPs from preterm labor have never been examined. This study was therefore conducted to describe the concentrations of MMP-2, TIMP-1, MMP-8 and MMP-9 in the CMP in relation to gestational age, IL-8 as an indicator of inflammation, compartment of the CMP, and preterm labor.

METHODS

An aliquot of the distal plug compartment facing the vaginal microflora (CMP-dist) was collected from non-pregnant (n = 15), early pregnant (n = 15) and term pregnant women (n = 15). Whole CMPs shed during active vaginal term (n = 15) and preterm (n = 4) labor were also included. Protein concentrations were determined by enzyme-linked immunosorbent assay (ELISA).

RESULTS

MMP-2 was not detectable in the non-pregnant CMP-dists whereas high concentrations were found in early pregnancy followed by an 85% decline at term. High concentrations of TIMP-1 were found in both the non-pregnant and early pregnant CMP-dists with a 90% decline at term. Consequently, the molar TIMP/MMP ratio was 40 in the non-pregnant state and 0.2 at term. The MMP-2 and TIMP-1 concentrations were alike in the CMP-dists and the whole CMPs.MMP-8, MMP-9, and IL-8 were mainly found in the distal CMP compartment. MMP-8 and MMP-9 concentrations were several fold increased in this compartment during pregnancy compared to the non-pregnant state. In the preterm whole CMPs, MMP-8, MMP-9 and IL-8 were 2 to 5 fold increased compared to term whole CMPs.

CONCLUSIONS

These results suggest that CMP MMP-2 reflects the non-leukocyte dependent cervical remodeling that occurs in early pregnancy, whereas MMP-8 and MMP-9 are involved in the defense against ascending infections primarily located to the distal compartment of the CMP. The upregulation of MMP-8, MMP-9 and IL-8 in whole CMPs from preterm labor may indicate the involvement of an intrauterine infection.

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.

Relation between mechanical properties and microstructure of human fetal membranes: an attempt towards a quantitative analysis

OBJECTIVE

We sought to measure the mechanical baseline behavior of fetal membranes in order to determine constitutive mechanical model parameters for fetal membranes, and to examine their relation to molecular correlates for mechanical function, i.e. collagen and elastin.

STUDY DESIGN

The uniaxial stress-strain response of nine human term fetal membranes was measured. Methods of nonlinear continuum mechanics were applied for the analysis of the stress-strain curves. Thickness of amnion and chorion were determined from histologic sections for each fetal membrane sample. Complementary biochemical analysis was performed to quantify the soluble collagen and soluble elastin components for each sample.

RESULTS

We report a straightforward histologic modality for measurements of amnion and chorion thickness. Average thickness of the amnion and chorion layers were 111+/-78 microm, and 431+/-113 microm, respectively, which are about twice larger than previously reported. The average content of acid-soluble elastin was 2.1% of wet weight and the one of pepsin/acetic acid-soluble collagen was 10.5% of dry weight. Our data show an inverse proportionality between soluble elastin and soluble collagen content. The low strain elastic modulus ranged between 10 and 25 kPa. Correlations were found between biochemical data and mechanical parameters: there is clearly a direct proportionality between small strain elastic modulus and elastin content. Further, a (less pronounced) direct correlation was observed also between soluble collagen content and the parameter governing the increase in stiffness at larger strains in the nonlinear mechanical model. The mechanical tests revealed a relatively low variability for samples from the same membrane but a large variation between donors. The proposed nonlinear model provides a good fit of the experimental data, with a coefficient of determination, R(2), typically in the range of 0.94. Membranes failure originated at the clamping points thus impairing the quantification of ultimate stress and strain. Thus, no correlation was found between maximum stress and collagen or elastin content.

CONCLUSIONS

This study provides a starting point for comprehensive quantitative analysis of the relationship between fetal membranes microstructure and their nonlinear deformation behavior. These insights could become useful in identifying potential medical interventions to prevent membranes rupture.

[Fetal membranes: embryological development, structure and the physiopathology of the preterm premature rupture of membranes]

Fetal membranes development is a complex process. The amniotic and exo-celomic cavities are appearing first. The rapid growth of the amniotic cavity is leading to the disappearance of the exo-celomic cavity and the chorion is merging with the decidua. Fetal membranes consist of three layers: the amnion and the chorion, issued from fetal tissues and the decidua issued from maternal tissue. A balance between the synthesis and the degradation of membranes components is physiologic throughout the gestation. Two main mechanisms are involved in the degradation process: apoptosis in the cellular compartment and matrix metalloproteinase (MMP) in the extracellular matrix. Regulation of MMP is depending on factors increasing their expression (cytokines) and factors decreasing their activity tissue inhibitor of metalloproteinases (TIMPS). Particular conditions can induce an unbalance between synthesis and degradation leading to the weakening of the membranes. Different factors can be associated to induce this unbalance: infection, hormonal factors, default in membranes fusion, oxidative stress and mechanic factors. In fine, the spontaneous rupture of the membranes is always occurring in regard of the uterine cervix after a process started several weeks before.

Patterns of cytokine profiles differ with pregnancy outcome and ethnicity

BACKGROUND

Preterm birth (PTB) is hypothesized to be an inflammatory response disease. However, no single factor alone is likely to explain PTB risk. It is more probable that coordinated networks of cytokines affect risk.

METHODS

Therefore, we examined the relationships between amniotic fluid (AF) cytokines/chemokines and related biomarkers in PTB and normal term deliveries in African Americans and Caucasians. Data were obtained from African American (41 preterm labor and 91 term labor) and Caucasian (105 preterm labor and 100 term labor) pregnant mothers. Pro-inflammatory cytokines and related molecules interleukin (IL)-1, IL-6, IL-8, and tumor necrosis factor- (TNF)-alpha, TNF soluble receptors (sTNFR1 and sTNFR2), and anti-inflammatory cytokine IL-10 that were all previously associated with PTB were studied. Correlations between biomarkers were calculated; differences of correlation coefficients between AF from African American and Caucasian samples in preterm labor and term labor were measured.

RESULTS

Multiple differences were observed between African American and Caucasian preterm and term birth groups. In term birth the strongest differences were between pro- and anti-inflammatory correlations, whereas in PTB differences were equally distributed between pro-inflammatory/anti-inflammatory and pro-inflammatory/pro-inflammatory correlations. Three correlation patterns differed significantly between AF from PTB African Americans with and without microbial invasion of the intra-amniotic cavity (MIAC); no differences were observed in Caucasians with MIAC.

CONCLUSION

Correlation analyses of cytokine measurements suggest coordinated interplay during pregnancy; significant differences exist between African Americans and Caucasians. Such analyses can serve as a means of understanding risk factors in these populations.

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.

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.

Amniotic membrane transplantation for corneal surface reconstruction after excision of corneolimbal squamous cell carcinomas in nine horses

OBJECTIVE

The purpose of this study was to evaluate the usefulness and effectiveness of permanent amniotic membrane transplantation as an adjunctive treatment to superficial keratectomy alone or combined with strontium-90 irradiation for treatment of equine corneolimbal squamous cell carcinoma (SCC) to decrease corneal scarring and recurrence rate.

STUDY

The retrospective case study included 11 horses (n = 12 eyes) diagnosed and treated for ocular SCC that involved the limbus and cornea. Nine of those horses (n = 9 eyes) were treated between 2002 and 2006, with superficial lamellar keratectomy alone or combined with strontium-90 irradiation and followed by placement of a permanent amniotic membrane graft in the surgical defect. The level of scarring (i.e. the clarity of the cornea) resulting with the use of amniotic membrane was subjectively compared to cases where a permanent bulbar conjunctival graft was performed following keratectomy combined with strontium-90 irradiation or cryotherapy (n = 3 eyes). Recurrence was defined as the postoperative and postirradiation regrowth of SCC in the same site and globe.

RESULTS

The nine horses that received an amniotic membrane graft after keratectomy alone or combined with irradiation showed a minimal level of scarring in a cornea that regained a greater transparency in comparison to the horses that were treated with a bulbar conjunctival graft. All of the horses that received an amniotic membrane graft had 226 +/- 218 days of follow-up without tumor recurrence (mean +/- SD), ranging from 21 days to 778 days.

CONCLUSIONS

The combination of superficial keratectomy alone or associated with beta-irradiation and permanent amniotic membrane transplantation is an effective treatment of corneal or corneolimbal SCC in horses. The placement of an amniotic membrane material represents an alternative surgical procedure to bulbar conjunctival grafts, especially if there is a lack of bulbar conjunctiva tissue available after tumor resection or if a particularly large corneal resection is necessary. The amniotic membrane is incorporated into the corneal defect and seems to create noticeably much less scarring than a corneal defect covered by bulbar conjunctiva.

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.

Serum lipid oxidizibility in term premature rupture of the membranes

OBJECTIVE

In our previous studies we have shown that the process of term labor is associated with oxidative stress, as indicated by increased susceptibility of maternal serum lipids to copper induced peroxidation. In order to continue evaluating the role of oxidative stress in the labor process, we next tested whether term premature rupture of the membranes (PROM) is also associated with increased susceptibility of maternal serum lipids to copper induced peroxidation.

DESIGN

A controlled prospective study.

SETTING

Tertiary care centre.

POPULATION

31 healthy women with term PROM and 19 healthy pregnant women with intact membranes. The women were matched for maternal and gestational age.

METHODS

Venous blood was drawn from the women (up to 6h after rupture of the membranes and prior to labor in the PROM group), and the kinetics of copper-induced oxidation of serum lipids ex vivo were monitored spectroscopically at 37 degrees C by continuous recording of absorbance at 245 nm.

RESULTS

The lag phase, reflecting resistance of serum lipids to oxidation, was similar in the PROM group when compared to the control group (43.7+/-3.2 versus 41.9+/-1.6 min, P=0.61). However, the maximal rate of oxidation (V(max)) and the maximal accumulation of absorbing products (OD(max)) were shorter in the PROM group when compared to the control group (5.14+/-0.26 versus 6.29+/-0.4010(-3) OD(245) nm/min, P=0.016; 0.61+/-0.03 versus 0.71+/-0.04 OD(245) nm, P=0.07).

CONCLUSION

As opposed to term labor, term PROM is not associated with increased maternal systemic oxidative stress when compared to normal pregnant women. The role for oxidative stress in preterm PROM warrants further studies.

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.

Differential activation of mitogen activated protein kinases and nuclear factor-κB in lipopolysaccharide-treated term and preterm amnion cells

Intrauterine exposure to amniotic sac infection elicits an inflammatory response from the fetus, which is associated with elevated levels of fetal plasma proinflammatory cytokines, i.e. interleukin-6 (IL-6). We have recently demonstrated that the severity of fetal inflammatory response in terms of gestation period is greater in preterm fetuses than in term fetuses. The activation of mitogen activated protein kinases (MAPKs) and nuclear factor kappa B (NF-kappaB) is known to be associated with up-regulation of proinflammatory cytokine gene expression in many cell types. In the present study, therefore, we studied patterns of MAPK and NF-kappaB activation following treatment with bacterial lipopolysaccharide (LPS) in amnion cells obtained from placentas of varying gestational ages to assess whether or not MAPKs and NF-kappaB are differentially regulated during gestation. MAPK phosphorylation was investigated by immunoblot analysis with phosphospecific antibodies. Transient phosphorylations of extracellular signal-regulated kinase (ERK) 1/2 and c-Jun N-terminal kinase (JNK) were observed in LPS-treated amnion cells, with the degree of phosphorylation being more pronounced in preterm cases. The results of NF-kappaB-dependent reporter gene expression and electrophoretic mobility shift assay (EMSA) of NF-kappaB were similar to those of ERK 1/2 and JNK activity. To assess whether the results of in vitro observations reflected in vivo results, we further analyzed amniotic fluid and cord blood IL-6 levels in preterm deliveries with placental inflammation. The analysis also revealed a significantly higher level of IL-6 in cases of </=31 weeks gestation when compared with those of more than 31 weeks (P<0.001). All these findings strongly suggest that there is an inverse relationship between gestational age and fetal inflammatory response during human gestation, and that differences in the intensity of MAPK activation and NF-kappaB-dependent transcription pathways are elements of the major underlying mechanism.