Increased concentration of pro-matrix metalloproteinase 9 in term fetal membranes overlying the cervix before labor: implications for membrane remodeling and rupture

OBJECTIVES: Regional structural alterations that develop before labor are important in the mechanisms of both physiologic and pathologic membrane rupture, because they are also detected in preterm prelabor rupture of the fetal membranes, the most common cause of preterm birth (as great as 60%). Matrix metalloproteinases are located in the fetal membranes and are the main mediators of extracellular matrix degradation. The objective of this study was to examine whether gelatinases (matrix metalloproteinases 2 and 9) could be involved in the development of these regional structural changes seen at term before labor. STUDY DESIGN: Fetal membranes from patients undergoing elective cesarean delivery were regionally sampled from over the cervix (cervical membranes) and midway between this area and the placental edge (midzone). Fetal membranes obtained after spontaneous labor and delivery at term were also regionally sampled. Matrix metalloproteinase 2 and 9 activities were assessed by gelatin zymography, whereas total matrix metalloproteinase 9 protein was determined by enzyme-linked immunosorbent assay. RESULTS: Zymography only detected activity corresponding to the pro-matrix metalloproteinase 2 (72 kd) and 9 (92 kd) forms in prelabor fetal membranes. Although the levels of pro-matrix metalloproteinase 2 showed no regional differences, the pro-matrix metalloproteinase 9 level was higher in the cervical area than in the midzone (2.5 +/- 0.98 vs 0.76 +/- 0.28 optical density units/20 microg protein; P <.01). The concentration of pro-matrix metalloproteinase 9 protein in the cervical area was also significantly higher than that in the midzone (6.69 +/- 4.8 vs 1.58 +/- 1.14 ng/mg protein; P <.01). After delivery both pro-matrix metalloproteinase 2 and 9 activities were elevated, whereas pro-matrix metalloproteinase 9 protein activity showed no regional difference between the rupture site and midzone (23.47 +/- 4.5 vs 25. 3 +/- 6.2 ng/mg protein). Active bands of matrix metalloproteinases 2 (66 kd) and 9 (83 kd) were also detected after delivery. CONCLUSION: This study suggests that a specific regional induction of pro-matrix metalloproteinase 9 occurs in the cervical area before labor and may play a role in "programming" this area for subsequent rupture after activation 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.     

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

OBJECTIVE: Increased matrix metalloproteinase 2 expression and activity are associated with premature rupture of fetal membranes. A proapoptotic protein produced in response to deoxyribonucleic acid fragmentation, p53, can bind to the matrix metalloproteinase 2 gene promoter and cause increased gene expression. It promotes apoptosis by inducing the expression of the proapoptotic bax gene and inhibiting the antiapoptotic bcl-2 gene. This study was undertaken to investigate the expression pattern of apoptotic elements in pregnancy complications that may cause increased expression of the gene for matrix metalloproteinase 2. STUDY DESIGN: Amniochorial membranes were collected from the following groups of women: (1) women with premature rupture of fetal membranes, (2) women with preterm labor and intact membranes, and (3) women with term labor after vaginal delivery. Deoxyribonucleic acid fragmentation was tested with ligation-mediated polymerase chain reaction and the terminal deoxynucleotidyl transferase-mediated biotinylated deoxyribonucleoside triphosphate end-labeling assay. Matrix metalloproteinase 2, p53, bcl-2, and bax gene expression patterns were studied with quantitative competitive polymerase chain reaction. Statistical analysis was performed with the Tukey-Kramer multiple comparison test. RESULTS: Quantitative competitive polymerase chain reaction documented a 10-fold increase in the expression of the gene for matrix metalloproteinase 2 in premature rupture of fetal membranes with respect to term and preterm labor. This induction coincided with an increase in the expressions of the proapoptotic genes p53 and bax and a drop in the expression of the antiapoptotic gene bcl-2. Ligation-mediated polymerase chain reaction revealed deoxyribonucleic acid fragmentation in specimens from premature rupture of fetal membranes and not in those from preterm labor or labor at term. Histochemical analysis documented fragmented deoxyribonucleic acid in chorionic and amniotic cells. CONCLUSION: This study suggests that apoptosis is associated with premature rupture of fetal membranes. Deoxyribonucleic acid fragmentation, associated with elevations in the levels of the two proapoptotic gene products evaluated (p53 and bax ) and a drop in the level of the antiapoptotic bcl-2, was seen in premature rupture of the fetal membranes. Induction of matrix metalloproteinase 2 may be a function of p53 gene expression increase in premature rupture of fetal membranes.     

Nitric oxide metabolite levels in preterm labor

AIM: To investigate the role of nitric oxide metabolites as markers of infection in subjects with preterm labor or preterm premature rupture of membranes (PTPROM). PTPROM means that there was spontaneous rupture of fetal membrane before the onset of labor and gestational age was <37 weeks. This occurs because of imbalance between matrix metalloproteinase and tissue inhibitor of matrix metalloproteinase. The cause of this imbalance that leads to degradation of collagen causing PTPROM is infection. The bactericidal, fungicidal, viricidal and tumoricidal activities of macrophages are determined in part by elaboration of nitric oxide, hence nitric oxide levels have been found to be increased in infections. METHODS: During an 18-month period 50 women with preterm labor or PTPROM and 50 controls were enrolled prospectively. Blood and urine samples were obtained for analysis of nitric oxide metabolites. Patients with known causes of preterm labor were excluded. RESULT: The nitric oxide metabolites, which included both nitrite levels and citrulline levels were significantly higher both in blood as well as urine in patients with preterm labor and PTPROM compared to controls. Serum nitrite levels in subjects with preterm labor were 376.5 +/- 345 nmol/L while in subjects with PTPROM they were 295.7 +/- 161.1 nmol/L and in controls the levels were 62.7 +/- 33.9 nmol/L. Serum citrulline levels in subjects with preterm labor were 5293.8 +/- 2916.7 nmol/L; in PTPROM they were 6536.6 +/- 609.91 nmol/L and in controls they were 949.8 +/- 67.1 nmol/L. On comparing patients with preterm labor, those in whom preterm labor could not be inhibited had statistically significant higher levels of nitrite in both serum and urine (482.9 +/- 387.7 nmol/L and 754.5 +/- 336.5 nmol/L, respectively) compared to patients in whom labor could be inhibited (172.2 +/- 61.9 nmol/L and 401.8 +/- 236.9 nmol/L, respectively). The citrulline levels were also higher among the group who delivered preterm for both serum and urine (5355.4 +/- 3229.7 nmol/L and 11 482.8 +/- 2541.4 nmol/L, respectively) compared to patients in whom labor could be inhibited (5260.2 +/- 2897.08 nmol/L and 10 651.4 +/- 1502.7 nmol/L, respectively) but this did not reach statistical significance. CONCLUSION: Higher nitric oxide metabolites in women with preterm labor are marker of subclinical infection.     

Thrombin-dependent regulation of matrix metalloproteinase (MMP)-9 levels in human fetal membranes.

OBJECTIVE: Amniochorion matrix metalloproteinase (MMP)-9 levels increase during labor, reaching a maximum in patients with preterm premature rupture of membranes (PPROM). Bleeding is a major risk factor for PPROM. Since such hemorrhage into the tissue factor-enriched decidua induces intense thrombin formation, we determined whether thrombin stimulates MMP levels in amniochorionic membranes. STUDY DESIGN: Fetal membrane (amniochorion) cultures were maintained in media with and without thrombin, lipopolysaccharide (LPS), thrombin receptor agonist peptide (TRAP)-14, and the anti-inflammatory steroid, dexamethasone (DEX). Concentrations of MMP-9, MMP-1, and tissue inhibitor of metalloproteinase (TIMP)-1 in culture media were measured by ELISA and normalized to total cell protein. RESULTS: The presence of thrombin induced MMP-9 levels. TRAP-14, a thrombin receptor agonist, also significantly increased MMP-9 levels, suggesting that thrombin-induced changes in MMP-9 expression were mediated through the thrombin receptor. Conversely, levels of MMP-1 and TIMP-1 were not affected by thrombin treatment, indicative of specificity of its action. The presence of LPS increased the concentration of MMP-9 and MMP-1. In contrast, DEX treatment significantly reduced MMP-9 levels. CONCLUSION: Our findings clearly demonstrated that thrombin treatment selectively increased the concentration of MMP-9 in culture media of amniochorionic membranes. Our results provide a potential mechanism through which alterations in hemostasis promote PPROM through thrombin-dependent stimulation of MMP-9.     

Inhibition of binding of bacteria to amniochorionic membranes by amniotic fluid.

The immunological composition of amniotic fluids is shown to be of such a lower order of activity that its role in fetal protection may be limited. Also, amniotic fluids were found not to have classical antibiotic activity. Amniotic fluids (25/31), however, were found to inhibit, by 27.5% to 88.2%, three target bacteria from binding to discs of amniochorionic membranes. This inhibition is also demonstrable with the monosaccharides alpha-D(+)-fucose, D(+)-galactose, alpha-D-glucose, alpha-D-lactose and bovine serum albumin-lactose conjugate, whereas other glycoconjugates enhanced bacterial binding. This demonstrates that the test bacteria bind to the amniochorionic membranes using bacterial lectins. In intraamniotic infection bacterial lectins may be complexed by amniotic fluid glycoconjugates which prevent the bacteria from binding to the amniochorionic membranes. This would explain asymptomatic infection and in the absence or reduced levels of the glycoconjugates the bacteria would bind to the amniochorionic membranes giving rise to symptomatic infection.     

Amniotic fluid nitric oxide metabolite levels and nitric oxide synthase localization in feto-placental tissues are modified in association with human labor

Nitric oxide (NO) has a relaxant effect on uterine smooth muscle and may be implicated in maintaining uterine quiescence during pregnancy. In order to investigate the role of nitric oxide in human parturition, we have measured NO metabolite levels in maternal and fetal compartments in association with labor, both at term and preterm. We have also examined the localization and distribution of NO synthase (NOS) isoforms in placentas and fetal membranes after term and preterm delivery by means of immunohistochemistry. Although no differences were present in maternal and fetal blood and in maternal urine among groups, we found that NO metabolite concentrations were higher in amniotic fluid collected from women in labor than in non-laboring patients, both at term (15.4+/-1.6 vs. 6.8+/-0.6 microM/mg creatinine) and preterm (16.7+/-2.0 vs. 7.0+/-0.8 microM/mg creatinine). Ir-bNOS staining appeared to be decreased in fetal membranes collected after spontaneous labor at term and preterm. In contrast, a stronger staining for iNOS was detected in trophoblast cells of fetal membranes from women in labor than in those from non-laboring women. We suggest that NOS isoenzymes in fetal placental tissues are differently regulated and might play different roles during pregnancy.     

Thrombin-dependent regulation of matrix metalloproteinase (MMP)-9 levels in human fetal membranes*

Objective.?Amniochorion matrix metalloproteinase (MMP)-9 levels increase during labor, reaching a maximum in patients with preterm premature rupture of membranes (PPROM). Bleeding is a major risk factor for PPROM. Since such hemorrhage into the tissue factor-enriched decidua induces intense thrombin formation, we determined whether thrombin stimulates MMP levels in amniochorionic membranes.

Study design.?Fetal membrane (amniochorion) cultures were maintained in media with and without thrombin, lipopolysaccharide (LPS), thrombin receptor agonist peptide (TRAP)-14, and the anti-inflammatory steroid, dexamethasone (DEX). Concentrations of MMP-9, MMP-1, and tissue inhibitor of metalloproteinase (TIMP)-1 in culture media were measured by ELISA and normalized to total cell protein.

Results.?The presence of thrombin induced MMP-9 levels. TRAP-14, a thrombin receptor agonist, also significantly increased MMP-9 levels, suggesting that thrombin-induced changes in MMP-9 expression were mediated through the thrombin receptor. Conversely, levels of MMP-1 and TIMP-1 were not affected by thrombin treatment, indicative of specificity of its action. The presence of LPS increased the concentration of MMP-9 and MMP-1. In contrast, DEX treatment significantly reduced MMP-9 levels.

Conclusion.?Our findings clearly demonstrated that thrombin treatment selectively increased the concentration of MMP-9 in culture media of amniochorionic membranes. Our results provide a potential mechanism through which alterations in hemostasis promote PPROM through thrombin-dependent stimulation of MMP-9.     

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

OBJECTIVE: Degradation of the extracellular matrix in fetal membranes has been implicated in the process of parturition and rupture of membranes. Matrix metalloproteinases (MMPs) are enzymes capable of degrading extracellular matrix including collagen. Tissue inhibitors of matrix metalloproteinases (TIMPs) inhibit the activity of MMPs by covalently binding to the enzymes. MMP-2 degrades Type IV collagen and TIMP-2 is its specific inhibitor. The objective of this study was to determine if human parturition, rupture of membranes (term and preterm) and microbial invasion of the amniotic cavity (MIAC) are associated with changes in the concentrations of MMP-2 and TIMP-2 in amniotic fluid. STUDY DESIGN: A cross-sectional study was conducted with women in the following categories: 1) term with intact membranes, in labor and not in labor; 2) preterm labor and intact membranes who delivered at term, who delivered preterm and preterm labor with MIAC; 3) preterm premature rupture of membranes (PROM) with and without infection; 4) term and preterm PROM not in labor; and 5) midtrimester. MMP-2 and TIMP-2 concentrations in amniotic fluid were determined using sensitive and specific immunoassays. RESULTS: The concentration of TIMP-2 increased with advancing gestational age (r = 0.6, p < 0.001). No correlation was found between MMP-2 concentrations and gestational age. Human parturition and rupture of membranes (term and preterm) and in patients with intact membranes were not associated with changes in the amniotic fluid MMP-2 concentrations. In contrast, 1) patients with spontaneous labor (term and preterm) had significantly lower median concentrations of TIMP-2 compared to those not in labor (p < 0.05 for both); 2) MIAC in women with preterm labor and preterm PROM was associated with a significant decrease in amniotic fluid TIMP-2 concentrations (p < 0.04 for both comparisons); 3) Rupture of the membranes (term and preterm) was also associated with a significant decrease in the amniotic fluid TIMP-2 concentrations (p < 0.05 and p < 0.03, respectively). CONCLUSIONS: Human parturition (preterm and term), rupture of fetal membranes (term and preterm) and intraamniotic infection are associated with a significant decrease in amniotic fluid TIMP-2 concentrations.     

人胎膜组织中E26转录因子1的表达及其与胎膜早破的关系

目的 检测人胎膜组织中E26转录因子1(Ets-1)的表达及定位,探讨其与胎膜早破发生的关系.方法 选择2007年2-11月在重庆医科大学附属第一医院住院分娩的产妇100例为研究对象,按足月与否、有无胎膜早破、分娩方式将其分为早产临产、未足月胎膜早破(PPROM)、足月临产、足月胎膜早破(TPROM)组,以足月择期刮宫产产妇为对照组,每组各20例,分娩后采集其胎膜组织,用免疫组化链霉菌抗生物素蛋白-过氧化物酶连接(SP)法检测Ets-1蛋白的表达水平及定位,每组选取6例以逆转录(RT)-PCR技术检测Ets-1 mRNA的表达水平,并进行半定量分析.结果 (1)各组胎膜组织中Ets-1 mRNA的表达:早产临产、PPROM、足月临产、TPROM、对照组胎膜组织中Ets-1mRNA表达水平分别为0.342±0.016、0.603±0.027、0.325±0.013、0.582±0.075、0.139±0.012,PPROM组和TPROM组均高于对照组.分别比较,差异均有统计学意义(P<0.05);早产临产组与足月临产组,PPROM组与TPROM组比较,差异均无统计学意义(P>0.05).(2)Ets-1蛋白在胎膜组织的定位:Ets-1蛋白集中在羊膜和绒毛膜的间质层、滋养层细胞的胞质和胞核中表达;细胞内可见清晰的棕黄色颗粒.在羊膜上皮细胞中未见Ets-1蛋白表达.(3)各组胎膜组织中Ets-1蛋白的表达:早产临产、PPROM、足月临产、TPROM、对照组胎膜组织中Ets-1蛋白表达水平分别为0.552±0.018、2.853±0.174、0.538±0.042、2.731±0.090、0.214±0.013,PPROM组与TPROM组均高于对照组,分别比较,差异均有统计学意义(P<0.05);但早产临产组与足月临产组,PPROM组与TPROM组胎膜组织分别比较,差异均无统计学意义(P>0.05).结论 Ets-1在人类胎膜组织中有表达,且在胎膜早破时表达水平升高.     

TNF-alpha promotes caspase activation and apoptosis in human fetal membranes

Purpose: Increased amniotic fluid tumor necrosis factor (TNF) is a marker of infection when associated with preterm labor and preterm premature rupture of the amniochorionic membranes (PROM). We have noted increased apoptosis in membranes derived from women with PROM. This study examines the role of TNF in promoting fetal membrane apoptosis. Methods: Amniochorion (n = 8), collected at the time of elective repeat cesarean section prior to labor from normal term gestation, were placed in an organ explant system. After 48 h in culture, the membranes were stimulated with recombinant TNF- (20 ng/mL) for 24 h. Tissue frozen after stimulation was subjected to RT-PCR to study the expression of TNF-induced caspase genes. ELISA assayed the levels of proapoptotic p53 in tissues and cell death related nuclear matrix protein (NMP) in tissue culture supernatants. The activity of caspases in tissue homogenates was measured using substrates specific for caspase 2, 3, 6, 8, and 9. Results were analyzed by using the Wilcoxon nonparametric test for paired samples. A p < 0.05 was considered significant. Results: RT-PCR showed induction of caspases 2, 8, and 9 (caspase cascade initiators) in human fetal membranes after TNF stimulation. Caspases 3 and 6 (effector caspases) expression was constitutive in both TNF stimulated- and control membranes. Caspases, 2, 3, 8, and 9 activity was significantly higher in TNF-stimulated tissues compared with control, whereas, no significant change in caspase 6 activity was noticed. TNF-stimulated tissues released increased levels of NMP (24.03 U/mL) compared with control (13.5U/mL) (p = 0.03). TNF also increased p53 levels in the tissues (0.05 ng/mL) compared with control cultures (0.03 ng/mL; p = 0.02). Conclusions: TNF increases proapoptotic p53 levels and caspase activities in fetal membranes. Increased NMP reflects cell death.     

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.     

Bacteria and inflammatory cells reduce chorioamniotic membrane integrity and tensile strength

Bacteria and the inflammatory response they engender are implicated in the pathophysiology of premature rupture of fetal membranes and preterm birth. We tested the hypothesis that bacteria and polymorphonuclear neutrophils may have both separate and combined effects in weakening the amniochorionic membrane, and thus predispose to premature rupture of membranes. We examined how three parameters of membrane integrity (bursting tension, work to rupture, and elasticity) were affected by standardized preparations (10(9) cfu/mL) of group B streptococci or Staphylococcus aureus in the presence or absence of purified human neutrophils (32 x 10(6)/mL). In addition, effects of purified human neutrophil elastase were evaluated. Exposure to either group B streptococcus or S aureus decreased membrane strength, elasticity, and work to rupture. Only activated neutrophils had significant effects on membrane strength. Membrane exposure to S aureus plus neutrophils led to an additive weakening of fetal membranes. On the other hand, group B streptococci did not interact with neutrophils to yield a significant further weakening of the membranes. Elastase (150 U/mL) also weakened the membrane. The results were correlated with measures of protease (Azocoll and ninhydrin assays) and peroxidase (dimethoxybenzidine) activity. Our findings support the concept that human neutrophils and their constituent enzymes may act in concert with bacteria and their protease(s) in weakening amniochorion, and may possibly predispose to premature rupture of membranes in some women. These observations require clinical correlations.     

New peptides, hormones and parturition.

This brief review emphasizes the importance of three novel discovered factors produced by fetal membranes, placenta and/or by the fetus itself in regulating uterine contractility. We have shown that, as reported for other hormones and substances, nitric oxide and endothelin may influence myometrial activity in an autocrine/paracrine manner interacting with other well-known agents such as prostaglandins, oxytocin and hormones. We also demonstrated that different isoforms of nitric oxide synthase (NOS) may play different roles throughout gestation and during labor. We have suggested that another peptide produced by trophoblast cells, adrenomedullin, may affect, directly or indirectly, myometrial contractility during pregnancy, although much remains to be learned about the mechanisms controlling adrenomedullin expression by the feto-placental tissues cells during pregnancy. Continued research is necessary to better define the complex interactions that result in parturition, both at term and preterm, and to allow a more rational approach to management of the premature labor, exploring new possible pharmacological solutions.     

Increased oxidative stress in human fetal membranes overlying the cervix from term non-labouring and post labour deliveries

Enzymatic breakdown of the collagen-rich extracellular matrix (ECM) that connects the amnion and chorion layers of the fetal membranes is one of the key events leading to rupture of membranes. Oxidant stress caused by increased formation of reactive oxygen species and/or reduced antioxidant capacity may predispose to membrane rupture, a major cause of preterm birth. The aim of this study was to determine the effect of human labour and supracervical (SC) apposition on antioxidant enzymes and 8-isoprostane (a marker of lipid peroxidation). To determine the effect of human labour on oxidative stress status, fetal membranes from the SC site (SCS) were collected from women at term Caesarean section (no labour), and from the site of membrane rupture (SOR) after spontaneous labour onset and delivery (post labour). To determine the effect of SC apposition on oxidative stress status, amnion was collected from the SCS and a distal site (DS) in women at term Caesarean section in the absence of labour. The release of 8-isoprostane was significantly higher in amnion from the SCS compared to DS, and in fetal membranes from the SOR compared to the SCS. Glutathione peroxidase (GPx) and superoxide dismutase (SOD) activity were lower in amnion from the SC compared to DS. SOD gene expression and enzyme activity were lower in fetal membranes after labour. There was no difference in expression or activity in catalase, GPx and glutathione reductase (GSR) between no labour and post labour fetal membranes. In primary amnion cells, SOD supplementation significantly augmented IL-1β induced MMP-9 expression and activity. In summary, non-labouring SC fetal membranes are characterised by reduced antioxidant enzyme activity when compared to distal membranes, and, as such, may be more susceptible to oxidative damage and thus membrane rupture.     

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

OBJECTIVE: The objective of this study was to investigate the predictive factors of premature rupture of the membranes (preterm PROM). METHODS: The study was undertaken with cervical secretions collected from 72 consenting singleton pregnant women between 20 and 33 weeks of gestation. The levels of interleukin (IL) 1alpha, IL-1beta, IL-6, IL-8, matrix metalloproteinase (MMP) 1, MMP-2, MMP-9, tissue inhibitors of matrix metalloproteinase (TIMP) 1, TIMP-2, granulocyte elastase, and fetal fibronectin in cervical diluted specimens were measured by immunoassay, and the uterine cervix was assessed by transvaginal ultrasonography. Demographic, obstetric, clinical, neonatal, and laboratory data were analyzed by univariate analysis, multiple logistic regression, and receiver operator characteristic curve analysis. RESULTS: Preterm PROM occurred in 6 women, and 63 women delivered at term. Multiple logistic regression analysis indicated a significant independent association with preterm PROM for the cervical IL-6 levels and cervical length. The receiver operator characteristic curve analysis revealed that an IL-6 level of >/=240 pg/ml in cervical secretions and a cervical length of 相似文献