Control of peripartal collagenolysis in the human chorion-decidua

Unraveling sex-specific risks of knee osteoarthritis before menopause: Do sex differences start early in life?

OBJECTIVE

Sufficient evidence within the past two decades have shown that osteoarthritis (OA) has a sex-specific component. However, efforts to reveal the biological causes of this disparity have emerged more gradually. In this narrative review, we discuss anatomical differences within the knee, incidence of injuries in youth sports, and metabolic factors that present early in life (childhood and early adulthood) that can contribute to a higher risk of OA in females.

DESIGN

We compiled clinical data from multiple tissues within the knee joint-since OA is a whole joint disorder-aiming to reveal relevant factors behind the sex differences from different perspectives.

RESULTS

The data gathered in this review indicate that sex differences in articular cartilage, meniscus, and anterior cruciate ligament are detected as early as childhood and are not only explained by sex hormones. Aiming to unveil the biological causes of the uneven sex-specific risks for knee OA, we review the current knowledge of sex differences mostly in young, but also including old populations, from the perspective of (i) human anatomy in both healthy and pathological conditions, (ii) physical activity and response to injury, and (iii) metabolic signatures.

CONCLUSIONS

We propose that to close the gap in health disparities, and specifically regarding OA, we should address sex-specific anatomic, biologic, and metabolic factors at early stages in life, as a way to prevent the higher severity and incidence of OA in women later in life.

Creation of a novel synthetic amniotic fluid for use in fetal therapy with in vitro testing on human amniotic membranes

BACKGROUND

Normal saline or lactated Ringer's solutions are usually infused at the time of fetal interventions; however, the effect of these fluids on the amniotic membranes has never been assessed. Given both the significant differences between the composition of normal saline solution, lactated Ringer's solution, and amniotic fluid and the significant risk of prematurity after fetal interventions, an investigation is warranted.

OBJECTIVE

This study aimed to evaluate the effect of current amnioinfusion fluids on the human amnion compared with a novel synthetic amniotic fluid.

STUDY DESIGN

Amniotic epithelial cells from term placentas were isolated and cultured per protocol. A synthetic amniotic fluid was created with similar electrolyte, pH, albumin, and glucose concentrations to human amniotic fluid, termed "Amnio-well." The cultured human amniotic epithelium was exposed to normal saline solution, lactated Ringer's solution, and Amnio-well. As a control, 1 group of cells remained in culture media. Cells were evaluated for apoptosis and necrosis. A second analysis to examine if cells could be "rescued" was performed, wherein the cells were allowed to remain in the culture media for an additional 48 hours after amnioinfusion. Subsequently, tissue testing with human amniotic membrane explants was evaluated similarly. Immunofluorescent intensity studies were undertaken to evaluate reactive oxygen species-mediated cell damage. Real-time quantitative polymerase chain reaction was used to evaluate gene expression in apoptotic pathways.

RESULTS

With simulated amnioinfusion, 44%, 52%, and 89% of amniotic epithelial cells were alive after exposure to normal saline solution, lactated Ringer's solution, and Amnio-well, respectively, compared with 85% in control (P<.001). After amnioinfusion and attempted cell rescue, 21%, 44%, 94%, and 88% of cells were alive after exposure to normal saline solution, lactated Ringer's solution, Amnio-well, and control, respectively (P<.001). In simulated amnioinfusion with full-thickness tissue explants, 68%, 80%, 93%, and 96% of cells were viable in normal saline solution, lactated Ringer's solution, Amnio-well, and control, respectively (P<.001). In culture, reactive oxygen species production was higher in normal saline solution, lactated Ringer's solution, and Amnio-well than in control (4.9-, 6.6-, and 1.8-fold higher, respectively, P<.001); however, this could be mitigated in Amnio-well by adding ulin-A-statin and ascorbic acid. Gene expression data revealed abnormal signaling in the p21 and BCL2/BAX pathways with normal saline solution compared with control (P=.006 and P=.041); changes were not seen with Amnio-well.

CONCLUSION

In vitro, normal saline and lactated Ringer's solutions caused increased amniotic membrane reactive oxygen species and cell death. The use of a novel fluid similar to human amniotic fluid led to the normalization of cellular signaling and less cell death.

Serum Decorin, Biglycan, and Extracellular Matrix Component Expression in Preterm Birth

Preterm birth is a leading cause of infant morbidity and mortality. Decorin and biglycan are proteoglycans that play key roles in maintaining the connective tissue matrix and tensile strength of human fetal membranes and have been previously linked to PPROM. Extracellular matrix proteins, such as matrix metalloproteinase 2 (MMP-2), matrix metalloproteinase 9 (MMP-9), TIMP metallopeptidase inhibitor 1 (TIMP-1), TIMP metallopeptidase inhibitor 2 (TIMP-2), and collagen VI (COL-6), have also been linked to PPROM and may have utility in a serum-based screening model for this condition. To define the natural course of serum decorin and biglycan expression throughout the duration of healthy pregnancy, to explore patterns of serum decorin and biglycan expression in serum of asymptomatic women who go on to develop spontaneous preterm labor, and to investigate the potential role for matrix metalloproteinases, their inhibitors, and collagen VI in a serum-based screening model to predict PPROM. Serum decorin level decreases less than 1% per week, and serum biglycan decreases by 2.9% per week over the duration of healthy pregnancy. Serum decorin and biglycan concentrations do not differ in spontaneous preterm labor cases compared with those in controls. Mean concentrations of MMP-2, MMP-9, TIMP-1, TIMP-2, and COL-6 do not differ in PPROM cases compared with those in controls. We have demonstrated that serum decorin and biglycan concentrations remain stable throughout the duration of normal pregnancy and are not early indicators of preterm labor, while common MMPs, TIMPs, and collagen VI are not early indicators of PPROM.

Targeting mechanotransduction mechanisms and tissue weakening signals in the human amniotic membrane

Mechanical and inflammatory signals in the fetal membrane play an important role in extracellular matrix (ECM) remodelling in order to dictate the timing of birth. We developed a mechanical model that mimics repetitive stretching of the amniotic membrane (AM) isolated from regions over the placenta (PAM) or cervix (CAM) and examined the effect of cyclic tensile strain (CTS) on mediators involved in mechanotransduction (Cx43, AKT), tissue remodelling (GAGs, elastin, collagen) and inflammation (PGE₂, MMPs). In CAM and PAM specimens, the application of CTS increased GAG synthesis, PGE₂ release and MMP activity, with concomitant reduction in collagen and elastin content. Co-stimulation with CTS and pharmacological agents that inhibit either Cx43 or AKT, differentially influenced collagen, GAG and elastin in a tissue-dependent manner. SHG confocal imaging of collagen fibres revealed a reduction in SHG intensity after CTS, with regions of disorganisation dependent on tissue location. CTS increased Cx43 and AKT protein and gene expression and the response could be reversed with either CTS, the Cx43 antisense or AKT inhibitor. We demonstrate that targeting Cx43 and AKT prevents strain-induced ECM damage and promotes tissue remodelling mechanisms in the AM. We speculate that a combination of inflammatory and mechanical factors could perturb typical mechanotransduction processes mediated by Cx43 signalling. Cx43 could therefore be a potential therapeutic target to prevent inflammation and preterm premature rupture of the fetal membranes.

SMAD7 regulates proinflammatory and prolabor mediators in amnion and myometrium

Preterm birth continues to be a significant public health problem. Infection (bacterial and or viral) and inflammation, by stimulating proinflammatory cytokines, adhesion molecules, and matrix metalloproteinase 9 (MMP9), play a central role in the rupture of membranes and myometrial contractions. SMAD7 has been implicated in regulating the inflammatory response; however, no studies have been performed with regard to human labor. In this study, we determined the effect of spontaneous human labor and prolabor mediators on SMAD7 expression in myometrium and fetal membranes. Functional studies were employed to investigate the effect of siRNA knockdown of SMAD7 (siSMAD7) in regulating infection and inflammation-induced prolabor mediators. SMAD7 mRNA and protein expression were significantly higher with spontaneous term labor, compared to no labor, in myometrium and fetal membranes. SMAD7 expression was also significantly higher in amnion from women with preterm chorioamnionitis. The proinflammatory cytokines IL1B and TNF, the bacterial product fsl-1, and the viral dsRNA analog poly(I:C) significantly increased SMAD7 in myometrial cells and amnion cells. In myometrial cells, siSMAD7 cells significantly decreased cytokine (IL6) and chemokine (CXCL1, CXCL8, CCL2 are also known as GRO-alpha, interleukin (IL)-8 and monocyte chemotactic protein-1 (MCP-1)) production induced by IL1B, TNF, and fsl-1. There was also a decrease in the expression of adhesion molecules intercellular adhesion molecule 1 (ICAM1) and vascular cell adhesion molecule 1 (VCAM1) in siSMAD7 cells, and MMP9 expression. In amnion, siSMAD7 cells treated with IL1B also decreased cytokine and chemokine production, ICAM1 and MMP9 expression. In conclusion, we report a proinflammatory role for SMAD7 in human gestational tissues, with SMAD7 silencing attenuating the inflammatory response.

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.

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.

SLIT3 is increased in supracervical human foetal membranes and in labouring myometrium and regulates pro-inflammatory mediators

PROBLEM

Inflammation is associated with preterm birth, a worldwide healthcare issue. SLIT3 has a role in inflammation, and thus, the purpose of this study was to determine the effect of SLIT3 on labour mediators in human gestational tissues.

METHOD OF STUDY

SLIT3 protein expression was performed using immunohistochemistry in foetal membranes and myometrium with no labour and after labour. Foetal membranes were also obtained from a distal site (DS) and supracervical site (overlying the cervix; SCS). SLIT3 gene silencing was achieved using siRNA in primary amnion and myometrial cells. Pro-inflammatory and pro-labour mediators were evaluated by qRT-PCR, ELISA and gelatin zymography.

RESULTS

SLIT3 expression was greater in foetal membranes from the SCS compared with DS and in myometrium after term spontaneous labour onset. SLIT3 siRNA in primary amnion and myometrial cells decreased IL-1β-induced pro-inflammatory cytokine gene expression and release (IL-6 and IL-8) and MMP-9 gene expression and release. In amnion cells, SLIT3 siRNA knockdown decreased IL-1β-induced COX-2 expression and prostaglandin PGE2 release. There was no effect of SLIT3 siRNA on IL-1β-induced NF-κB transcriptional activity.

CONCLUSION

Our results demonstrate that SLIT3 is increased with labour, and both our amnion and our myometrial studies describe a pro-inflammatory effect of SLIT3 in these tissues.

Sphingosine kinase: a novel putative target for the prevention of infection-triggered preterm birth

Preterm birth is defined as any delivery before 37 complete weeks of gestation. It is a universal challenge in the field of obstetrics owing to its high rate of mortality, long-term morbidity, associated human suffering and economic burden. In the United States, about 12.18% deliveries in 2009 were preterm, producing an exorbitant cost of $5.8 billion. Infection-associated premature rupture of membranes (PROM) accounts for 40% of extremely preterm births (<28 weeks of gestation). Major research efforts are directed towards improving the understanding of the pathophysiology of preterm birth and ways to prevent or at least postpone delivery. Endothelin-1 (ET-1) is a potent vasoconstrictor that plays a significant role in infection-triggered preterm birth. Its involvement in a number of pathological mechanisms and its elevation in preterm delivered amniotic fluid samples implicate it in preterm birth. Sphingosine kinase (SphK) is a ubiquitous enzyme responsible for the production of sphingosine-1-phosphate (S1P). S1P acts as second messenger in a number of cell proliferation and survival pathways. SphK is found to play a key role in ET-1 mediated myometrial contraction. This review highlights SphK as a prospective target with great potential to prevent preterm birth.

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 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.

Matrix metalloproteinases and their tissue inhibitors in endometrial remodelling and menstruation

The architecture of the human endometrium is extensively remodelled during the course of each normal menstrual cycle, unlike most other tissues and organs which undergo very little change during adult life. During menstruation, when loss of most of the functionalis layer occurs, there is concomitant epithelial regrowth; repair of the luminal surface is complete almost as bleeding ceases. During the proliferative phase of the cycle and under the influence of rising oestrogen levels, the stromal cells, glands and blood vessels undergo rapid proliferation which results in tissue thickening. Following ovulation (around day 14 of the idealized 28-day cycle), the secretory phase of the cycle is characterized by increasing tortuosity of the spiral arterioles and glands and increased glandular secretory activity. After about day 22, decidualization of many of the stromal fibroblasts also occurs, the resultant decidual cells having many characteristics typical of epithelial cells. Periods of tissue oedema are apparent both in mid-proliferative (days 8–11) and mid-secretory (days 20–23) endometrium. Late in the cycle, there is regression of the tissue as menstruation is initiated.

The effect of relaxin on the female anterior cruciate ligament: Analysis of mechanical properties in an animal model

BACKGROUND

The peptide hormone relaxin, found in pregnant and non-pregnant females, has been shown to have collagenolytic effects on ligamentous tissue. Relaxin receptors have recently been identified on the human female anterior cruciate ligament (ACL). Relaxin may affect the load bearing properties of the female ACL and contribute to non-contact ACL injuries.

HYPOTHESIS

The administration of recombinant relaxin+/-estrogen will lead to a significant decrease in ACL integrity in the guinea pig model.

STUDY DESIGN

Controlled laboratory study.

METHODS

Adult female guinea pigs were divided into three experimental groups. Group 1 (n=4) was administered only 20 microg/h of recombinant porcine relaxin for 3 weeks. Group 2 (n=4) was administered 20 microg/h of recombinant porcine relaxin and 5 microg/h of estradiol for 3 weeks. Group 3 (n=4) served as both a normal control before surgical transection of the ACL and a positive ACL tear control after transection. All hormones were administered using separate implanted osmotic pumps. ACL laxity was tested by implanting radio-opaque markers in the femur and tibia of each leg. After applying a standard anterior force (22 N), the distance between markers was measured radiographically at day 0 and day 21. The animals were then sacrificed and the ACL's were analyzed for load-to-failure using a material testing machine.

RESULTS

Load-to-failure testing indicated that animals treated with relaxin only had significantly weaker ACL's (micro=40.4 N, p=0.001) compared to controls (micro=64.1 N). The relaxin+estrogen group (micro=32.7 N) was also significantly weaker than controls (p=0.007). There were no statistical differences between relaxin and relaxin+estrogen groups. Both relaxin only and relaxin+estrogen groups showed an increase in anterior translation of the tibia after 3 weeks of infusion, but it did not achieve statistical significance.

CONCLUSIONS

Relaxin significantly alters the mechanical properties of the ACL in an animal model.

CLINICAL RELEVANCE

The effects of relaxin, possibly in conjunction with estrogen, may contribute to a comprehensive etiology for human female non-contact ACL injuries.

Preterm birth in Caucasians is associated with coagulation and inflammation pathway gene variants

Spontaneous preterm birth (<37 weeks gestation—PTB) occurs in ∼12% of pregnancies in the United States, and is the largest contributor to neonatal morbidity and mortality. PTB is a complex disease, potentially induced by several etiologic factors from multiple pathophysiologic pathways. To dissect the genetic risk factors of PTB a large-scale high-throughput candidate gene association study was performed examining 1536 SNP in 130 candidate genes from hypothesized PTB pathways. Maternal and fetal DNA from 370 US Caucasian birth-events (172 cases and 198 controls) was examined. Single locus, haplotype, and multi-locus association analyses were performed separately on maternal and fetal data. For maternal data the strongest associations were found in genes in the complement-coagulation pathway related to decidual hemorrhage in PTB. In this pathway 3 of 6 genes examined had SNPs significantly associated with PTB. These include factor V (FV) that was previously associated with PTB, factor VII (FVII), and tissue plasminogen activator (tPA). The single strongest effect was observed in tPA marker rs879293 with a significant allelic (p = 2.30×10⁻³) and genotypic association (p = 2.0×10⁻⁶) with PTB. The odds ratio (OR) for this SNP was 2.80 [CI 1.77–4.44] for a recessive model. Given that 6 of 8 markers in tPA were statistically significant, sliding window haplotype analyses were performed and revealed an associating 4 marker haplotype in tPA (p = 6.00×10⁻³). The single strongest effect in fetal DNA was observed in the inflammatory pathway at rs17121510 in the interleukin-10 receptor antagonist (IL-10RA) gene for allele (p = 0.01) and genotype (p = 3.34×10⁻⁴). The OR for the IL-10RA genotypic additive model was 1.92 [CI 1.15–3.19] (p = 2.00×10⁻³). Finally, exploratory multi-locus analyses in the complement and coagulation pathway were performed and revealed a potentially significant interaction between a marker in FV (rs2187952) and FVII (rs3211719) (p<0.001). These results support a role for genes in both the coagulation and inflammation pathways, and potentially different maternal and fetal genetic risks for PTB.

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.

Progestin-inflammatory cytokine interactions affect matrix metalloproteinase-1 and -3 expression in term decidual cells: implications for treatment of chorioamnionitis-induced preterm delivery

CONTEXT

Chorioamnionitis (CAM)-elicited preterm delivery (PTD) is associated with elevated amniotic fluid levels of IL-1beta and TNF-alpha. We hypothesized that IL-1beta and TNF-alpha may induce matrix metalloproteinase (MMP)-1 and MMP-3 activity to promote PTD by degrading decidual and fetal membranes and cervical extracellular matrix.

OBJECTIVE

Our objective was to evaluate: 1) MMP-1 and MMP-3 expression in decidual sections from uncomplicated term, idiopathic preterm, and CAM-complicated deliveries, and 2) the separate and interactive effects of IL-1beta, TNF-alpha, medroxyprogesterone acetate (MPA), and a p38 MAPK inhibitor (SB203580) on MMP-1 and MMP-3 expression in term decidual cells (DCs).

INTERVENTIONS AND MAIN OUTCOME MEASURES

Decidua were immunostained for MMP-1 and MMP-3. Cultured term DCs were incubated with estradiol (E2) or E2 plus MPA with or without IL-1beta or TNF-alpha with or without SB203580. ELISA and Western blotting assessed secreted MMP-1 and MMP-3 levels, quantitative real-time RT-PCR assessed mRNA levels, and substrate gel zymography was used to determined MMP-1 and MMP-3 proteolytic activity.

RESULTS

MMP-1 and MMP-3 immunostaining was more prominent in CAM-complicated decidua vs. control preterm and term decidual specimens (P < 0.05). Compared with basal outputs by DCs incubated with E2, TNF-alpha enhanced MMP-1 and MMP-3 secretion by 14 +/- 3- and 9 +/- 2-fold, respectively, and IL-1beta increased MMP-1 and MMP-3 secretion by 13 +/- 3- and 19 +/- 2-fold, respectively (P < 0.05). Addition of MPA lowered basal MMP-1 and MMP-3 outputs by 70%, whereas the TNF-alpha- and IL-1beta-enhanced MMP-1 and MMP-3 levels were blunted by more than 50% (P < 0.05). SB203580 suppressed TNF-alpha- and IL-1beta-induced MMP-1 and MMP-3 secretion by severalfold. Western blotting confirmed the ELISA results, and mRNA levels corresponded with MMP-1 and MMP-3 protein levels. MMP-1 and MMP-3 proteolytic activity was confirmed by substrate gel zymography.

CONCLUSION

Augmented DC-expressed MMP-1 and MMP-3 in CAM-complicated pregnancies may promote PTD via decidual, fetal membrane, and cervical extracellular matrix degradation. Effects of progestin-p38 MAPK signaling inhibition on cytokine-enhanced MMP-1 and MMP-3 expression in term DCs suggest alternative mechanisms to prevent CAM-induced PTD.

Evidence of in vitro differential secretion of 72 and 92 kDa type IV collagenases after selective exposure to lipopolysaccharide in human fetal membranes

Premature rupture of chorioamniotic membranes complicated with intrauterine infection has been associated to degradation of extracellular matrix (ECM), which could explain local morphological changes. We used a culture system in which the chorioamniotic membranes form two independent chambers, allowing for the selective stimulation of either the amnion (AMN) and/or the choriodecidua (CHD) regions. Lipopolysaccharide (500 ng/ml) was added to the AMN and/or the CHD; secretions and gelatinolytic activity of matrix metalloproteinase (MMP)-2 and MMP-9 were measured in both compartments by enzyme-linked immunosorbent assay (ELISA) and zymography. Secretions of TIMP-1, TIMP-2 and TIMP-4 were measured by ELISA. Both metalloproteinases were immunolocalized in tissue sections. All stimulation modalities induced a similar proMMP-2 and proMMP-9 secretion pattern in the CHD with concentrations of 2.49 ng/ml and 90.91 pg/ml, respectively; the AMN showed no significant changes. The active forms of both enzymes did not change with any stimulation modality. TIMP-1, TIMP-2 and TIMP-4 secretions remained without significant changes (P = 0.41). ECM degradation and structural disarrangement were evident after stimulation. Secretion of proMMP-2 and proMMP-9 mainly in the CHD, presence of active forms associated to the tissue and minor changes in TIMPs secretion could favor ECM degradation and explain the weakening and thinning associated with the pathological rupture of chorioamniotic membranes.

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

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

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Idiopathic vaginal bleeding during pregnancy as the only clinical manifestation of intrauterine infection

OBJECTIVE

To determine the frequency and clinical significance of microbial invasion of the amniotic cavity (MIAC) in patients with vaginal bleeding in the absence of placenta previa, preterm labor or preterm premature rupture of membranes (PROM).

STUDY DESIGN

This retrospective cohort study included patients who presented with vaginal bleeding between 18 and 35 weeks, and underwent an amniocentesis shortly after admission for the assessment of the microbiologic status of the amniotic cavity and/or fetal lung maturity. Amniotic fluid was cultured for aerobic and anaerobic bacteria, as well as genital mycoplasmas. Patients presenting with preterm labor, preterm PROM, placenta previa, overt placental abruption, and an intrauterine device in situ were excluded, as well as those with local cervical bleeding. MIAC was defined as a positive amniotic fluid culture. Analysis was conducted with non-parametric statistics.

RESULTS

One hundred and fourteen patients met the entry criteria. MIAC was detected in 14% of cases (16/114). Patients with vaginal bleeding and a gestational age < 28 weeks at the time of amniocentesis had a significantly higher frequency of MIAC than those with a gestational age 28 weeks [25% (13/52) vs. 4.8% (3/62), respectively; p < 0.01]. Ureaplasma urealyticum was the microorganism most frequently isolated from the amniotic fluid. Except for one case admitted at 33 weeks, all patients with MIAC had an early preterm delivery 32 weeks. Patients with vaginal bleeding and MIAC had a shorter procedure-to-delivery interval than those without MIAC [MIAC, median survival 19 days (95% CI 10-27 days) vs. no MIAC, median survival 50 days (95% CI 37-62 days); p < 0.0001]. Patients with vaginal bleeding and MIAC had a significantly lower gestational age at delivery and lower birth weight than those with vaginal bleeding and negative amniotic fluid cultures (for gestational age, median 25 weeks, range 21-33 weeks vs. median 37 weeks, range 19-42 weeks, respectively; p < 0.01, and for birth weight, median 750 grams, range 520-1820 grams vs. 2800 grams, range 520-4880 grams, respectively; p < 0.01), as well as a higher frequency of subsequent preterm PROM [81.3% (13/16) vs. 9.2% (9/98); p < 0.01].

CONCLUSIONS

MIAC was detected in 14% of patients with 'idiopathic' vaginal bleeding and was associated with subsequent preterm PROM and early preterm delivery. Vaginal bleeding may be the only clinical manifestation of MIAC, and it predisposes to adverse outcome.

The value of cervical length and plasma proMMP-9 levels for the prediction of preterm delivery in pregnant women presenting with threatened preterm labor

OBJECTIVE

To assess the value of plasma proMMP-9 levels in predicting the progress of threatened preterm labor to true preterm labor and delivery within 7 days of presentation, along with the ultrasonographic measurement of cervical length.

STUDY DESIGN

The study included sixty two pregnant women presented in the 2nd Department of Obstetrics and Gynecology of University of Athens at Aretaieion Hospital with threatened preterm labor. On subjects' presentation, cervical length was evaluated with transvaginal ultrasonography, plasma proMMP-9 levels were measured with the use of a solid phase enzyme immunoassay, and maternal characteristics (smoking, history of preterm delivery and parity) as well as the use of tocolytics were recorded. Subjects were followed up for premature delivery within 7 days. ROC analysis for plasma proMMP-9 levels was performed and logistic regression analysis was used for the evaluation of the prognostic effect of the parameters.

RESULTS

The only significant predictors for establishment of true preterm labor and delivery within 7 days of presentation were cervical length (with cutoff value 15 mm: odds ratio=0.022, 95% CI=0.002-0.243, p=0.002) and plasma proMMP-9 (with cutoff value 67.15 ng/ml: odds ratio=0.035, 95% CI=0.003-0.388, p=0.006). The combination of the adopted proMMP-9 and cervical length cutoff values was characterized by a sensitivity of 90.9% and a specificity of 98.3% for predicting the progress to true preterm labor and delivery.

CONCLUSION

Plasma proMMP-9 levels could possibly serve as a predictive factor for the progress of threatened preterm labor to true preterm labor and delivery within 7 days of presentation, along with the ultrasonographic evaluation of cervical length.

The role of nuclear factor kappa B in human labour

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

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

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

Isolation, characterization, and expression of stromelysin-1 in primary tumors of dogs

OBJECTIVE

To isolate and characterize the cDNA sequence of canine stromelysin-1 (matrix metalloproteinase [MMPI-3), screen various naturally developing primary tumors of dogs, and assess the effect of stromelysin-1 on survival of dogs with cancer.

SAMPLE POPULATION

3 canine cell lines and biopsy specimens of primary tumors collected from 54 dogs.

PROCEDURE

3 canine cell lines and biopsy specimens of primary tumors collected from 54 dogs at the University of Illinois Veterinary Teaching Hospital were used in the study. Primer sets based on human stromelysin-1 and consensus sequences were designed for expression, screening, and isolation. Two additional primer sets were designed for screening. Samples were assayed at least in duplicate. Data were analyzed for differences in expression of stromelysin-1 on the basis of sex, age, metastasis, malignant versus nonmalignant tissue origin, and duration of patient survival.

RESULTS

A 1,479-bp cDNA nucleotide sequence was amplified from established canine cell lines. The open reading frame encoded a protein consisting of 478 amino acids. This sequence was 70% to 88% homologous with stromelysin-1 of other species at the amino acid level. Fifty-four samples were screened for stromelysin-1. Of these, 34 (63%) had positive results and 20 (37%) had negative results for expression. Stromelysin-1 and metastasis were associated with a poor prognosis for survival.

CONCLUSIONS AND CLINICAL RELEVANCE

Stromelysin-1 is a potential activator of other members of the MMP family. Additional studies are needed to investigate the relationship between stromelysin-1 production and aggressive biological behavior of tumors in dogs.

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.

Are alterations in plasma protease concentrations during labor associated with poor obstetric outcomes?

OBJECTIVE

The purpose of this study was to assess the association between abnormal connective tissue remodeling during labor as reflected by plasma concentrations of extracellular matrix remodeling proteolytic enzymes and adverse obstetric outcomes.

STUDY DESIGN

A prospective observational study of 176 nulliparous women who attended the antenatal clinics at the Mercy Hospital for Women (Melbourne, Australia) from 1999 to 2000.

RESULTS

Patients with a prolonged second stage (>120 minutes) had a significantly increased plasma concentration of matrix metalloproteinase 9 after delivery compared with control subjects (P<.001); patients in labor who underwent an emergency caesarean delivery had a significantly lower concentration (P<.001). Patients with a prolonged duration of labor (>11 hours) had a significantly lower urokinase plasminogen activator plasma concentration compared with control subjects (P<.01).

CONCLUSION

Altered plasma concentrations of extracellular matrix remodeling proteolytic enzymes, matrix metalloproteinase 9, and urokinase plasminogen activator were found to be associated with abnormal labor and delivery outcomes. This finding may provide a useful predictor of abnormal obstetric outcomes.

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

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

Expression and localization of cell adhesion molecules in human fetal membranes during parturition

There is increasing evidence to support the view that human parturition represents an inflammatory process. We have previously demonstrated that parturition is associated with leukocyte invasion and pro-inflammatory cytokine production in the cervix and myometrium. Furthermore, we have shown that several cell adhesion molecules are upregulated in these tissues during labor. In fetal membranes, previous studies have shown intercellular adhesion molecule-1 (ICAM-1) upregulation in association with labor. The role of other adhesion molecules has not been explored. The aims of this study were, therefore, to determine the expression of ICAM-1, platelet endothelial cell adhesion molecule (PECAM), vascular cell adhesion molecule (VCAM) and E-selectin in pre- and post-laboring amnion and choriodecidua and to identify cell types responsible for their expression. Biopsies of fetal membranes were obtained from pregnant women delivered by caesarean section before the onset of labor (n = 8) and following spontaneous vaginal delivery (n = 8). Cell adhesion molecules were identified using immunohistochemistry and messenger RNA expression quantified using Northern analysis. We found that following labor, ICAM-1 mRNA expression was significantly upregulated in amnion and choriodecidua (P < 0.05). PECAM mRNA expression was also increased in choriodecidua (P < 0.05). The main cell types responsible for adhesion molecule expression were leukocytes, amniotic epithelial cells and endothelial cells. The upregulation of ICAM-1 and PECAM mRNA expression in fetal membranes following labor provides further evidence that fetal membranes play an important role in the inflammatory process of parturition.

Mechanisms of abruption-induced premature rupture of the fetal membranes: Thrombin enhanced decidual matrix metalloproteinase-3 (stromelysin-1) expression

OBJECTIVE

The aim of the study was to evaluate thrombin and progestin effects on matrix metalloproteinase-3 expression in term decidual cells as a mechanism of abruption-related preterm delivery.

STUDY DESIGN

Decidual cells were isolated by standard techniques, purified to homogeneity, grown to confluence, and passaged. Cultures were primed with 10 (-8) M estradiol or estradiol plus 10 (-7) progestin and then incubated in a defined medium with corresponding steroid(s) plus or minus thrombin or the protease-activated thrombin receptor-1 agonist for 24 hours. Secreted matrix metalloproteinase-3 levels were assessed by enzyme-linked immunosorbent assay, and immunoblotting and messenger RNA levels were measured by Northern blotting and quantitative reverse transcription-polymerase chain reaction.

RESULTS

Immunoreactive matrix metalloproteinase-3 levels were inhibited 66% by estradiol plus progestin versus estradiol ( P < .05). Thrombin elicited a dose-dependent reversal in this progestin inhibition, producing a 2.5-fold increase at 2.5 U/mL ( P < .05) that attained 33% of matrix metalloproteinase-3 levels in parallel incubations with estradiol plus thrombin. Protease-activated thrombin receptor-1 agonist mimicked 60% of thrombin-enhanced matrix metalloproteinase-3 output. Immunoblotting validated the enzyme-linked immunosorbent assay results. Northern blotting and quantitative reverse transcription-polymerase chain reaction demonstrated corresponding effects on steady-state messenger RNA levels.

CONCLUSION

Abruption-generated thrombin promotes preterm delivery by mediating fetal membrane extracellular matrix degradation via enhanced decidual cell matrix metalloproteinase-3 expression, whereas progesterone blunts this thrombin-induced effect.

Functionally significant SNP MMP8 promoter haplotypes and preterm premature rupture of membranes (PPROM)

Matrix metalloproteinase 8 (MMP8), an enzyme that degrades fibrillar collagens imparting strength to the fetal membranes, is expressed by leukocytes and chorionic cytotrophoblast cells. We identified three single nucleotide polymorphisms (SNPs) at -799C/T, -381A/G and +17C/G from the major transcription start site in the MMP8 gene, and determined the functional significance of these SNPs by analyzing their impact upon MMP8 promoter activity and their association with preterm premature rupture of membranes (PPROM). The minor alleles +17 (G) and -381 (G) were in complete linkage disequilibrium. A promoter fragment containing the three minor alleles had 3-fold greater activity in chorion-like trophoblast cells (BeWo, JEG-3 and HTR-8/SVneo) compared with the major allele promoter construct. Electrophoretic mobility shift assays revealed differences in BeWo nuclear protein binding to oligonucleotides representing the -381 and -799 SNPs, suggesting that the minor alleles have reduced transcription factor binding. A case-control study of African-American neonates using allele-specific primers revealed a statistically significant association between the three minor allele haplotype, which displays the highest MMP8 promoter activity in trophoblast cells, with PPROM with an odds ratio (OR) of 4.63 (P < 0.0001), whereas the major allele promoter appeared to be protective (OR = 0.52, P < 0.0002). None of the minor alleles were individually associated with PPROM. These findings demonstrate the functional significance of SNP haplotypes in the MMP8 gene and associations with obstetrical outcomes.

Interaction of cocultured decidual endothelial cells and cytotrophoblasts in preeclampsia

Disturbed cell-cell communication between trophoblasts and the maternal endothelium may be responsible for the deficient endovascular invasion seen in preeclampsia. In vitro studies have been hampered by lack of suitable models to directly examine interactions between these cell types. Using a bilayer coculture model, we examined the effect of decidual endothelial cells on matrix metalloproteinase secretion and the migration of cytotrophoblasts from preeclamptic pregnancies. Cells were incubated on semipermeable membranes in 20% or 2% O(2) with or without the tumor promoter phorbol 12-myristate 13-acetate, which activates matrix metalloproteinase-2 and -9 in endothelial cells. Cytotrophoblasts from preeclamptic pregnancies secreted significantly less matrix metalloproteinase-2 and -9 than their normal counterparts. Although decidual endothelial cells downregulated cytotrophoblast migration in normal pregnancy, this was not observed in cocultures with cytotrophoblasts from preeclamptic pregnancies. In addition, cytotrophoblasts from preeclamptic pregnancies altered phorbol myristate acetate-induced activation of endothelial matrix metalloproteinases. Hypoxia increased cytotrophoblast migration when cells were incubated alone but not in coculture with decidual endothelial cells due to increased adhesion between the two cell types. These results suggest dysfunctional interactive regulation of migration and matrix metalloproteinase secretion in preeclampsia that could result in abnormal endovascular trophoblast invasion of the maternal vasculature.

Matrix metalloproteinase-8 is expressed in human chorion during labor

OBJECTIVE

The purpose of this study was to investigate the expression of matrix metalloproteinase-8 by human fetal membranes during labor.

STUDY DESIGN

Fetal membranes were obtained from women who underwent normal labor or elective cesarean delivery at term. Matrix metalloproteinase-8 levels in fetal membranes were determined by enzyme-linked immunosorbent assay and Western blot; the expression of the matrix metalloproteinase-8 gene was detected by reverse transcription-polymerase chain reaction. Immunohistochemistry and in situ hybridization was performed to localize matrix metalloproteinase-8 protein and messenger RNA in intact membranes.

RESULTS

Matrix metalloproteinase-8 protein levels were increased 5-fold in fetal membranes from labor compared with membranes that were obtained from cesarean delivery. Western blots confirmed the presence of matrix metalloproteinase-8 in protein extracts. Reverse transcription-polymerase chain reaction, in situ hybridization, and immunohistochemistry demonstrated that matrix metalloproteinase-8 messenger RNA and protein were expressed almost exclusively in the chorion after labor.

CONCLUSION

We conclude that matrix metalloproteinase-8 is produced primarily by chorionic cells in human fetal membranes and that the level of matrix metalloproteinase-8 protein and messenger RNA expression in fetal membranes increases during labor.

Mechanisms of matrix metalloproteinase-9 and matrix metalloproteinase-2 inhibition by N-acetylcysteine in the human term decidua and fetal membranes

OBJECTIVE

The purpose of this study was to evaluate the effect of N-acetylcysteine on the activity and secretion of the matrix metalloproteinases in the decidua, amnion, and chorion and the secretion of the tissue inhibitor of matrix metalloproteinase-1.

STUDY DESIGN

Samples from eight nonlaboring women were taken at elective cesarean section and incubated in an in vitro organ culture in the absence or presence of N-acetylcysteine. Matrix metalloproteinase-2 and matrix metalloproteinase-9 activity was measured with the use of gel zymography. Western blot analysis was used to measure matrix metalloproteinase and tissue inhibitor of matrix metalloproteinase-1 secretion. Data were analyzed with the paired Student t test.

RESULTS

N-acetylcysteine had a direct inhibitory effect on matrix metalloproteinase-2 and matrix metalloproteinase-9 activity, regardless of tissue origin, starting at 1.0 mmol/L. In cultured media, 20 mmol/L N-acetylcysteine inhibited matrix metalloproteinase-2 and matrix metalloproteinase-9 activity in all three tissues. A differential response was demonstrated for matrix metalloproteinase-2 secretion, depending on the tissue that was studied. Its secretion was decreased in decidua at 10 mmol/L and 20 mmol/L; in amnion, the secretion was inhibited at 0.1 mmol/L and not affected at all in chorion. Matrix metalloproteinase-9 secretion was not affected in a statistically significant manner in any tissue. In the chorion, matrix metalloproteinase-9 showed a trend toward increased secretion. Tissue inhibitor of matrix metalloproteinase-1 secretion significantly decreased in the decidua at 20 mmol/L.

CONCLUSION

N-acetylcysteine, at higher concentrations, has an inhibitory effect on matrix metalloproteinase-2 and matrix metalloproteinase-9 activity, regardless of the tissue origin and the differential effect on secretion depending on the tissue and N-acetylcysteine concentration.

The matrix metalloproteinase system: changes, regulation, and impact throughout the ovarian and uterine reproductive cycle

The ovary and uterus undergo extensive tissue remodeling throughout each reproductive cycle. This remodeling of the extracellular environment is dependent upon the cyclic hormonal changes associated with each estrous or menstrual cycle. In the ovary, tissue remodeling is requisite for growth and expansion of the follicle, breakdown of the follicular wall during the ovulatory process, transformation of the postovulatory follicle into the corpus luteum, as well as the structural dissolution of the corpus luteum during luteal regression. In the uterus, there is extraordinary turnover of the endometrial connective tissue matrix during each menstrual cycle. This turnover encompasses the complete breakdown and loss of this layer, followed by its subsequent regrowth. With implantation, extensive remodeling of the uterus occurs to support placentation. These dynamic changes in the ovarian and uterine extracellular architecture are regulated, in part, by the matrix metalloproteinase (MMP) system. The MMP system acts to control connective tissue remodeling processes throughout the body and is comprised of both a proteolytic component, the MMPs, and a regulatory component, the associated tissue inhibitors of metalloproteinases. The current review will highlight the key features of the MMPs and tissue inhibitors of metalloproteinases, focus on the changes and regulation of the MMP system that take place throughout the estrous and menstrual cycles, and address the impact of the dynamic tissue remodeling processes on ovarian and uterine physiology.

Relaxin receptors in the human female anterior cruciate ligament

BACKGROUND

Noncontact anterior cruciate ligament injuries occur two to eight times more often in women than in men. Changes in ligament laxity and strength have been associated with female hormones such as relaxin.

HYPOTHESIS

Relaxin receptors are present within the female anterior cruciate ligament.

STUDY DESIGN

Controlled laboratory study.

METHODS

Remnants of anterior cruciate ligament were harvested from five women and five men undergoing routine ligament reconstruction. Relaxin was biotinylated and analyzed for biologic activity with use of the mouse interpubic ligament bioassay. Immunohistochemical localization of relaxin receptors was performed with appropriate negative controls and competitive binding assays to determine receptor specificity and saturability.

RESULTS

Anterior cruciate ligament sections from women but not from men showed uniform specific binding that was limited to synovial lining cells, stromal fibroblasts, and cells lining blood vessels. Specific binding was confirmed in the presence of a 2000-fold excess of human insulin, the structural homolog of relaxin, and competitive inhibition was demonstrated in the presence of a 2000-fold excess of unlabeled relaxin.

CONCLUSIONS

Relaxin exhibits specific saturable binding in the female anterior cruciate ligament, where specific relaxin receptors were present.

CLINICAL RELEVANCE

The high incidence of anterior cruciate ligament rupture in female athletes may be partially explained by the effects of relaxin.

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

OBJECTIVE

Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases that are expressed in many inflammatory conditions and contribute to connective tissue breakdown. Stromelysin 1 [matrix metalloproteinase 3 (MMP-3)], a novel member of this family, is produced in the context of infection and is able to activate the latent forms of other MMPs. The purpose of this study was to determine if parturition (either term or preterm), premature rupture of the membranes (PROM), and microbial invasion of the amniotic cavity are associated with changes in amniotic fluid concentrations of MMP-3.

STUDY DESIGN

A cross-sectional study was conducted, which included women who underwent transabdominal amniocentesis (n = 365) in the following categories: (1) mid-trimester with a subsequent normal pregnancy outcome (n = 84) and a subsequent fetal loss (n = 10); (2) preterm labor with intact membranes without microbial invasion of the amniotic cavity who delivered at term (n = 36), or prematurely (n = 50), and preterm labor with microbial invasion of the amniotic cavity (n = 25); (3) preterm PROM with (n = 25) and without (n = 26) microbial invasion of the amniotic cavity; (4) term with intact membranes in the absence of microbial invasion of the amniotic cavity, in labor (n = 52) and not in labor (n = 31); and (5) term with PROM in the absence of microbial invasion of the amniotic cavity and not in labor (n = 26). MMP-3 concentrations in amniotic fluid were measured by a sensitive and specific immunoassay that was validated for amniotic fluid. MMP-3 concentrations were normalized using logarithmic transformation for statistical analysis. Parametric statistics were used and a p value < 0.05 was considered statistically significant.

RESULTS

(1) MMP-3 was detected in 99.5% (363/365) of amniotic fluid samples, and its concentration did not change with advancing gestational age. (2) Spontaneous parturition at term and preterm was associated with a significant increase in amniotic fluid MMP-3 concentrations (p = 0.04 and p = 0.002, respectively). (3) Spontaneous rupture of membranes in term and preterm gestations was not associated with significant changes in amniotic fluid MMP-3 concentrations. (4) Intra-amniotic infection was associated with a significant increase in amniotic fluid MMP-3 concentrations in both women with preterm labor and intact membranes (p = 0.03), and women with preterm PROM (p = 0.02). (5) Subsequent fetal loss after genetic amniocentesis was not associated with significant changes in mid-trimester concentrations of amniotic fluid MMP-3.

CONCLUSIONS

(1) MMP-3 is a physiologic constituent of amniotic fluid. (2) MMP-3 may play a role in the mechanisms of human parturition and in the regulation of the host response to intrauterine infection.

Cytokines, prostaglandins and parturition--a review

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

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

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

Expression of matrix metalloproteinase (MMP)-2 and MMP-9 in human placenta and fetal membranes in relation to preterm and term labor

Extensive extracellular matrix (ECM) remodeling is found in many processes during human parturition at term and preterm. These include cervical ripening, fetal membrane rupture, and placental detachment from the maternal uterus. Matrix metalloproteinases (MMPs) are the main mediators of ECM degradation. The present study was designed to investigate the expression of MMP-2 and MMP-9 in human fetal membranes (FMs) and placental (PL) tissues with or without labor at preterm and term parturition. Both zymography and Western blot analysis showed that MMP-9 was significantly (P < 0.01) increased in preterm and term labor FM, compared with nonlabor. Term labor PL also had a much higher (P < 0.05) level of MMP-9 than that of term nonlabor. No significant difference in MMP-2 expression was found between labor and nonlabor tissues. Immunolocalization studies revealed a specific distribution pattern for MMP-2 and MMP-9. MMP-2 was localized to the amnion mesenchyme, chorion laeve trophoblast, decidua parietalis, and blood vessels in PL villi. MMP-9 was localized mainly to amnion epithelia, chorion laeve trophoblast, decidua parietalis, and PL syncytiotrophoblasts. Separate cell culture from different layers of FM and culture of purified PL trophoblast cells showed that PL syncytiotrophoblast and amnion epithelial cells exclusively produced MMP-9; chorion trophoblast cells secreted both MMP-2 and MMP-9, but amnion mesenchymal cells produced only MMP-2. We concluded that MMP-2 and MMP-9 exhibited cell-specific expression in the human PL. An increase in MMP-9 expression may contribute to degradation of the ECM in the FM and PL, thereby facilitating FM rupture and PL detachment from the maternal uterus at labor, both preterm and term.

Thrombin-enhanced matrix metalloproteinase-1 expression: a mechanism linking placental abruption with premature rupture of the membranes

OBJECTIVE

Given the strong clinical association between the decidual hemorrhage of placental abruption and subsequent preterm premature rupture of the membranes, we assessed the effects of thrombin on the expression of the potent interstitial collagenase, matrix metalloproteinase-1 (MMP-1), in cultured endometrial stromal and decidual cells.

STUDY DESIGN

Stromal cells derived from predecidualized cycling endometrium and decidual cells from term decidua were cultured in a defined medium containing estradiol, to mimic the hormonal milieu of the non-pregnant proliferative phase, or estradiol plus medroxyprogesterone acetate (MPA), to mimic the hormonal milieu of pregnancy, in the presence and absence of thrombin. Culture media were examined for MMP-1 protein levels and cell lysates were examined for steady-state MMP-1 mRNA levels.

RESULTS

MPA strongly inhibited MMP-1 levels in endometrial stromal and term decidual cells. However, thrombin overcame this suppression, producing MMP-1 levels that were several-fold higher than control levels.

CONCLUSION

Extrapolation of thrombin-enhanced MMP-1 expression in cultured endometrial stromal and decidual cells to the in vivo pregnant state provides an explanation for the strong association between placental abruption and preterm membrane rupture.

Identification of matrix metalloproteinase-9 in amniotic fluid and amniochorion in spontaneous labor and after experimental intrauterine infection or interleukin-1 beta infusion in pregnant rhesus monkeys

OBJECTIVE

The purpose of this study was to examine the roles of intrauterine infection, inflammation, and spontaneous labor on the expression of matrix metalloproteinase-9 in fetal membranes and amniotic fluid of late pregnant rhesus monkeys.

STUDY DESIGN

Pregnant rhesus monkeys with timed gestations were chronically catheterized to allow serial sampling of amniotic fluid before and during experimentally induced intrauterine inflammation. Six animals received group B streptococci into the chorionic-decidual space, and 4 animals received intra-amniotic interleukin-1 beta infusions (10 microg). Three additional animals were serially sampled by amniocentesis through late pregnancy until spontaneous term labor. Amniotic fluid samples were examined by zymography for matrix metalloproteinase-9 and -2 and Western immunoblot for matrix metalloproteinase-9 and -2 and tissue inhibitors of metalloproteinase-1 and -2. Fetal membranes were obtained at cesarean delivery during labor (before rupture), formalin fixed, and embedded in paraffin for immunocytochemistry of matrix metalloproteinase-9 and in situ hybridization of matrix metalloproteinase-9 messenger RNA. Tissues from 2 additional animals were collected as age-matched non-labor controls.

RESULTS

In amniotic fluid, the 92-kd latent matrix metalloproteinase-9 was detectable in late pregnancy and increased dramatically, followed by the appearance of the 83-kd active form before spontaneous term delivery. Amniotic fluid matrix metalloproteinase-2 levels (both latent and active forms) remained relatively constant throughout pregnancy and in labor. Both bacteria and interleukin-1 beta rapidly increased the signal of latent matrix metalloproteinase-9 without a consistent increase in the active form before the onset of labor. Chorionic-decidual inoculation of group B streptococci was followed by the expression of latent matrix metalloproteinase-9 before the appearance of group B streptococci in amniotic fluid or the onset of labor. Matrix metalloproteinase-2 increased to a new steady-state level or remained unchanged after group B streptococci inoculation or interleukin-1 beta infusion, respectively. Amniotic fluid tissue inhibitors of metalloproteinase-1 declined and tissue inhibitors of metalloproteinase-2 remained unchanged during early group B streptococci infection, after interleukin-1 beta infusion and on the day of spontaneous term labor. However, both tissue inhibitors of metalloproteinase-1 and -2 levels increased after preterm labor that was induced by group B streptococci. Immunocytochemistry localized matrix metalloproteinase-9 protein to amnion and chorion epithelial and mesenchymal cells and decidual stromal cells. Granular matrix metalloproteinase-9 staining was observed in the connective tissue layer of inflamed fetal membranes. In situ hybridization for messenger RNA confirmed the production of matrix metalloproteinase-9 by amnion and chorion.

CONCLUSION

Bacterial- and interleukin-1 beta-induced preterm labor and spontaneous term labor are preceded and accompanied by progressive increases in amniotic fluid matrix metalloproteinase-9 (92 kd) in rhesus monkeys. Amniotic fluid matrix metalloproteinase-9 may serve as a clinical marker for the onset of both preterm and term labor.

Amniotic fluid matrix metalloproteinase-8 indicates intra-amniotic infection

OBJECTIVE

This study was undertaken to determine whether matrix metalloproteinase-8, which is produced by neutrophils, is a useful marker for the detection of intra-amniotic infection.

STUDY DESIGN

We performed a case-control study using enzyme-linked immunosorbent assays to detect matrix metalloproteinase-8 in 77 amniotic fluid specimens that were obtained by amniocentesis from women with preterm contractions or preterm labor and intact fetal membranes (n = 66) and from women with preterm premature rupture of membranes (n = 11).

RESULTS

Thirty women had culture-proven intra-amniotic infection (cases), 21 of whom had intact membranes. After constructing receiver operating characteristic curves to establish the optimal threshold concentration of matrix metalloproteinase-8 for a positive test result, we detected matrix metalloproteinase-8 in 27 of 30 women with intra-amniotic infection; only 10 of 47 control specimens contained matrix metalloproteinase-8 (P <.001; odds ratio, 33.3; 95% CI, 8.4, 132.7). Matrix metalloproteinase-8 was present in 20 of 21 women with intact membranes and intra-amniotic infection and in only 10 of 45 control subjects (P <.001; odds ratio, 70.0; 95% CI, 8.3, 587.6). Among women with intact membranes, the sensitivity of the assay was 0.95 and the specificity was 0.78.

CONCLUSION

Our results indicate that matrix metalloproteinase-8 is highly correlated with intra-amniotic infection and that enzyme-linked immunosorbent assay for matrix metalloproteinase-8 may be a clinically useful test for the diagnosis of intra-amniotic infection in women with preterm contractions and preterm labor.

Amniotic fluid concentrations of matrix metalloproteinase 9 and tissue inhibitor of metalloproteinase 1 during pregnancy and labor

OBJECTIVE

This study was undertaken to determine whether obstetric factors affect the concentrations of matrix metalloproteinase 9 and tissue inhibitor of metalloproteinase 1 in the amniotic fluid.

STUDY DESIGN

We prospectively collected amniotic fluid samples from 109 women at various stages of pregnancy and labor and determined matrix metalloproteinase 9 and tissue inhibitor of metalloproteinase 1 concentrations by means of enzyme-linked immunosorbent sandwich assay systems. With multiple regression analysis we evaluated relationships between amniotic fluid matrix metalloproteinase 9 concentration and tissue inhibitor of metalloproteinase 1 concentration and the following factors: gestational age, presence of labor, cervical dilatation, membrane status, presence of clinical chorioamnionitis, and microbial colonization of the amniotic fluid.

RESULTS

The detectable presence of amniotic fluid matrix metalloproteinase 9 was independently associated with intra-amniotic infection, labor, cervical dilatation, and spontaneous rupture of membranes. Chorioamnionitis and amniotic fluid matrix metalloproteinase 9 concentrations were correlated with tissue inhibitor of metalloproteinase 1 levels.

CONCLUSIONS

Intra-amniotic infection, advanced labor, and rupture of membranes before the onset of labor were independently associated with the presence of matrix metalloproteinase 9 in the amniotic fluid. Both pathologic and physiologic processes appear to produce shifts in the balance between degradation and synthesis of the extracellular matrix.

Human fetal membranes: their preterm premature rupture

At the 1999 annual meeting of the Society for the Study of Reproduction there were three speakers in the minisymposium entitled "I've got to get out of here: fetal-maternal interactions involved in parturition". The primary focus was on research progress in understanding the mechanisms involved in human parturition. Although the title of the symposium emphasized the need to "get out", there was considerable emphasis on understanding the problem of "getting out too early" or preterm birth. While preterm birth is unusual in most species, it is of major clinical importance in the human. The data presented by one of the speakers is reviewed here with a focus on preterm labor and preterm premature rupture of the fetal membranes as mechanisms involved in the diverse pathology of preterm birth.