Second-trimester amniotic fluid interleukin-10 concentration predicts preterm delivery

Objective: Interleukin-6 (IL-6) is an inflammatory cytokine that has been shown to be elevated in the amniotic fluid of patients with preterm labor. On the other hand, interleukin-10 (IL-10) is an anti-inflammatory cytokine that has been shown to inhibit the synthesis of other cytokines. We hypothesized that amniotic fluid IL-10 in the early second trimester is low in patients who subsequently develop preterm labor, and because of its deficiency, excessive inflammatory responses associated with IL-6 elevation lead to preterm labor and delivery.

Study design: Amniotic fluid IL-6 and IL-10 levels were measured in 96 women who underwent genetic amniocentesis between 15 and 23 weeks' gestation. Levels of IL-6 and IL-10 were measured by immunoassay and correlated with demographic and pregnancy outcome information.

Results: Fifteen patients delivered at or before 36 weeks and 81 patients delivered after 36 weeks. There was an inverse correlation between amniotic fluid IL-10 concentration and gestational age at delivery. Similarly, an inverse correlation also existed between amniotic fluid IL-6 concentration and gestational age at delivery.

Conclusions: Both IL-10 and IL-6 levels in second-trimester amniotic fluid obtained at the time of genetic amniocentesis appeared to be higher in patients who subsequently developed preterm delivery. Therefore, low amniotic fluid IL-10 production during the second trimester does not seem to be an etiology for preterm labor.     

The anti-inflammatory limb of the immune response in preterm labor,intra-amniotic infection/inflammation,and spontaneous parturition at term: A role for interleukin-10

Objective. The anti-inflammatory limb of the immune response is crucial for dampening inflammation. Spontaneous parturition at term and preterm labor (PTL) are mediated by inflammation in the cervix, membranes, and myometrium. This study focuses on the changes in the amniotic fluid concentrations of the anti-inflammatory cytokine interleukin (IL)- 10. The objectives of this study were to determine whether there is a relationship between amniotic fluid concentrations of IL-10 and gestational age, parturition (at term and preterm), and intra-amniotic infection/inflammation (IAI).

Study design. A cross-sectional study was conducted including 301 pregnant women in the following groups: (1) mid-trimester of pregnancy who delivered at term (n = 112); (2) mid-trimester who delivered preterm neonates (n = 30); (3) term not in labor without IAI (n = 40); (4) term in labor without IAI (n = 24); (5) term in labor with IAI (n = 20); (6) PTL without IAI who delivered at term (n = 31); (7) PTL without IAI who delivered preterm (n = 30); (8) PTL with IAI who delivered preterm (n = 14). IL-10 concentrations in amniotic fluid were determined by a specific and sensitive immunoassay. Non-parametric statistics were used for analysis.

Results. (1) IL-10 was detectable in amniotic fluid and its median concentration did not change with gestational age from mid-trimester to term. (2) Patients in labor at term had a significantly higher median amniotic fluid IL-10 concentration than that of patients at term not in labor (p = 0.04). (3) Women at term in labor with IAI had a significantly higher median amniotic fluid IL-10 concentration than that of patients at term in labor without IAI (p = 0.02). (4) Women with PTL and IAI who delivered preterm had a significantly higher median amniotic fluid concentration of IL-10 than those without IAI who delivered preterm and than those who delivered at term (p = 0.009 and p < 0.001, respectively). (5) Among patients with preterm labor without IAI, those who delivered preterm had a significantly higher median amniotic fluid IL-10 concentration than those who delivered at term (p = 0.03).

Conclusions. The anti-inflammatory cytokine IL-10 is detectable in the amniotic fluid of normal pregnant women. Spontaneous parturition at term and in preterm gestation is associated with increased amniotic fluid concentrations of IL-10. IAI (preterm and at term) is also associated with increased amniotic fluid concentrations of IL-10. We propose that IL-10 has a role in the regulation of the immune response in vivo by initiating actions that dampen inflammation.     

Infection and labor. VI. Prevalence, microbiology, and clinical significance of intraamniotic infection in twin gestations with preterm labor

The purpose of this study was to establish the prevalence, microbiology, and outcome of microbial invasion of the amniotic cavity in twin gestation presenting with preterm labor and intact membranes. Amniocenteses were performed on both sacs of 46 women with twin gestations, preterm labor, and intact membranes. Indigo carmine was injected to ensure sampling of both amniotic sacs. Amniotic fluid was cultured for aerobic and anaerobic bacteria, Mycoplasma hominis, and Ureaplasma urealyticum. A positive amniotic fluid culture of at least one sac was noted in 10.8% (5/46) of patients admitted in preterm labor and in 11.9% (5/42) of women delivered of preterm neonates. Of the five patients with microbial invasion of the amniotic cavity, three had microorganisms isolated from both sacs. The presenting sac was involved in all cases, supporting an ascending route for microbial invasion of the amniotic cavity in twin gestation. Polymicrobial infection was found in three of the eight amniotic sacs with positive cultures. In two cases different organisms were isolated from each sac. All patients with positive amniotic fluid cultures were delivered of preterm infants within 48 hours of amniocentesis. Patients with positive amniotic fluid cultures presented with preterm labor at an earlier gestational age and with more advanced cervical dilatation than did women with negative amniotic fluid cultures. Clinical evidence of chorioamnionitis subsequently developed in two of five women with positive amniotic fluid cultures. The interval between amniocentesis and delivery was shorter in women with positive amniotic fluid cultures than in women with negative amniotic fluid cultures (median: 3.5 vs 168 hours, p less than 0.0001). Infants born to women with microbial invasion of the amniotic cavity had a lower median birth weight and a higher incidence of respiratory distress syndrome than those born to women with negative amniotic fluid cultures (birth weight: 1085 vs 1975 gm, p = 0.024; respiratory distress syndrome: 37.5% vs 8.3%, p = 0.04).     

Evaluation of amniotic fluid cytokines in preterm labor and intact membranes.

OBJECTIVE: To compare the amniotic fluid (AF) concentration of pro-inflammatory cytokines between women with preterm labor and intact membranes that delivered within 7 days, with those that delivered after 7 days of the amniocentesis according to the result of the AF culture. METHODS: Fifty-two women with preterm labor and intact membranes between 21 and 35 weeks of gestation were included in the study. Transabdominal amniocentesis was performed to rule out intra-amniotic infection, and AF concentrations of interleukin-1alpha (IL-1alpha), interleukin-1beta (IL-1beta), interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor (TNF) were determined with sensitive and specific enzyme-linked immunosorbent assays. Amniotic fluid was cultured for aerobic and anaerobic bacteria, Ureaplasma urealyticum, and Mycoplasma hominis. Exclusion criteria included preterm premature rupture of membranes, vaginal bleeding, multiple gestations, uterine anomalies, fetal congenital anomalies, ominous fetal heart rate tracings and fetal deaths. Proportions were compared using chi2 or Fisher's exact test. Receiver operator characteristic (ROC) curve analysis was performed for each cytokine for the prediction of delivery within 7 days. RESULTS: Sixty-two percent (32/52) of women delivered within 7 days and 38% (20/52) delivered after 7 days of amniocentesis. All women that delivered after 7 days of the procedure had negative AF cultures. In contrast, 28% (9/32) of women that delivered within 7 days had positive AF cultures and 72% (23/32) had negative AF cultures. Women that delivered within 7 days regardless of AF cultures had a lower birth weight and a shorter amniocentesis-to-delivery interval than those that delivered after 7 days of amniocentesis. Among women that delivered within 7 days, those with positive AF cultures had a lower gestational age at delivery and a higher frequency of histologic chorioamnionitis than those with negative AF cultures. The AF concentrations of all cytokines were significantly higher in women that delivered within 7 days with positive AF cultures than in those with negative AF cultures. Similarly, the AF concentrations of IL-1alpha, IL-6, and IL-8 were significantly higher in women that delivered within 7 days than those that delivered after 7 days of the amniocentesis, regardless of the AF culture results. Diagnostic indexes were calculated for all cytokines using critical values derived from ROC curve analysis for the prediction of delivery within 7 days. CONCLUSIONS: Women with preterm labor and intact membranes that delivered within 7 days had higher AF concentrations of pro-inflammatory cytokines than those who delivered after 7 days of the amniocentesis regardless of the AF culture results.     

Cytokine abundance in placental tissues: evidence of inflammatory activation in gestational membranes with term and preterm parturition

OBJECTIVES: This study of the changes in cytokine concentrations in gestational tissues from women with term and preterm labor was undertaken to assess the extent of inflammatory activation associated with spontaneous labor and delivery. STUDY DESIGN: Extracts of amniotic, chorionic-decidual, and placental tissues from women delivered at term before labor (n = 15), at term after labor (n = 15), and preterm (n = 31) were assayed for interleukin 1beta, interleukin 6, and interleukin 8. RESULTS: In amniotic tissues of women delivered by spontaneous labor at term the median interleukin-6, interleukin-8, and interleukin-1beta concentrations were 3.8 to 5.4 times those of tissues from women delivered at term without labor (P <.05, Mann-Whitney U test). Interleukin-6 and interleukin-8 concentrations were also significantly increased (3. 3-4 times) in chorionic-decidual tissues. Marked increases (approximately 3-6 times) in the concentrations of all 3 cytokines were observed in both amniotic and chorionic-decidual tissues from women with preterm deliveries with respect to those from women with term deliveries after labor. Cytokine concentrations were significantly correlated within amniotic tissues from both women with term delivery after labor and women with preterm delivery and also in preterm chorionic-decidual tissues but not preterm placental tissues. Concentrations of cytokines in the tissues of women delivered preterm were not significantly affected by mode of delivery, treatment with antibiotics, or twin birth. In preterm tissues with evidence of intrauterine infection only amniotic interleukin-1beta concentrations were significantly elevated (P <. 05). Little or no labor-related change in cytokine concentrations was seen within placental tissues. CONCLUSIONS: Increased cytokine abundance in gestational membranes associated with labor supports the view that an inflammatory process is involved in both term and preterm labor. This process does not, however, appear to be evident in the villous placenta.     

Maternal plasma and amniotic fluid dehydroepiandrosterone-sulfate concentrations in preterm labor and delivery

The purpose of this study was to determine whether preterm parturition is associated with changes in maternal plasma and amniotic fluid dehydroepiandrosterone-sulfate concentrations. A cross sectional study was constructed according to the gestational age at admission and response to tocolysis. Group 1 consisted of women admitted with preterm labor and intact membranes between 28 and 31 weeks and 6 days gestational age (n=40). Group 2 included 40 patients with preterm labor between 32 and 36 weeks gestational age. Both groups were classified into two subgroups: preterm delivery within seven days of admission and term delivery. Commercially available immunoassay kits validated for amniotic fluid analysis of DHEA-S, were used to measure maternal plasma and amniotic fluid DHEA-S concentrations. Maternal plasma DHEA-S concentrations were significantly higher in women with preterm labor who delivered preterm than in those who delivered at term. (Group 1: median 800 ng/ml [range 100–1100] vs. median 200 ng/ml [70–800],P<0.001; Group 2: median 850 ng/ml [300–1700] vs. median 300 ng/ml [90–1100],P<0.001). In contrast, no significant differences were detected in amniotic fluid DHEA-S concentrations. Our data suggest that the rise in maternal plasma DHEA-S concentrations observed in patients with preterm labor may be related to the effects of stress during labor.     

妊娠中期羊水中相关炎症介质预测早产的研究进展

早产指妊娠满28周至不足37周分娩,早产儿的多器官系统发育不成熟和相关并发症是导致新生儿发病和死亡的重要原因。早产防治的困难性主要在其多病因性,目前其发病机制尚不明确,多项研究表明感染是其主要因素,感染产生的炎症介质通过多种途径最终诱发宫缩,从而促进早产。此前较多采用胎儿纤维连接蛋白（FFN）、经阴道宫颈管长度测定、血清中相关炎症介质的检测等预测晚期症状性早产的发生,而对中期预测早产应用受限。已证实绒毛膜羊膜炎时妊娠组织产生的相关炎症介质如白细胞介素6（IL-6）、IL-16、C反应蛋白（CRP）、脂联素、抗菌肽等直接进入羊水中,同时羊膜腔穿刺术常规用于产前诊断领域,因此通过对妊娠中期羊水中相关炎症介质的进一步研究有望为中期预测早产提供新的方法。     

Value of placental microbial evaluation in diagnosing intra-amniotic infection

OBJECTIVE: To evaluate the ability of microbiologic and pathologic examination of the placenta to accurately diagnose intraamniotic infection and inflammation. METHODS: One hundred eighty-three women with a clinically indicated amniocentesis were enrolled prospectively. We applied our analysis to 56 women with evidence of preterm labor or preterm premature rupture of membranes who delivered within 48 hours of amniotic fluid testing results. Twenty-three patients, assessed for fetal lung maturity in the third trimester, served as controls. Amniotic fluid was cultured for aerobic, anaerobic, Ureaplasma, and Mycoplasma species. We used mass spectrometry to assess the degree of intraamniotic inflammation (Mass Restricted scoring). After delivery, microbiologic and histologic studies of the placenta were performed. These results were interpreted in comparison with the direct microbiologic and inflammatory analysis of the amniotic fluid. A sample size of 45 patients was required to show a test accuracy of 80% or more. RESULTS: Ninety-two percent of women with positive amniotic fluid cultures tested with at least one positive placenta culture. Eighty percent of women who had negative amniotic fluid cultures also tested with a positive placenta culture. The accuracy of placental cultures in predicting amniotic fluid infection varied from 44% to 57%. Placental pathology showed an accuracy of only 58% in diagnosing intraamniotic inflammation. CONCLUSION: Placental microbiologic and histologic studies poorly reflect the infectious and inflammatory status of the amniotic fluid. Results of such studies should be interpreted with caution in the management and future counseling of women with preterm labor or preterm premature rupture of membranes. LEVEL OF EVIDENCE: II.     

Human beta-defensin-2: a natural antimicrobial peptide present in amniotic fluid participates in the host response to microbial invasion of the amniotic cavity.

OBJECTIVE: Human beta-defensin-2 (HBD-2) is a potent antimicrobial peptide that is part of the innate immune response. The purpose of this study was to determine whether HBD-2 is present in amniotic fluid and if its concentration changes with microbial invasion of the amniotic cavity (MIAC) and labor. STUDY DESIGN: Amniotic fluid was retrieved by amniocentesis from 318 patients in the following groups: (1) mid-trimester (n=75); (2) term not in labor (n=28) and in labor (n=51); (3) preterm labor and intact membranes without MIAC who delivered at term (n=36), who delivered preterm without MIAC (n=52), and preterm labor with MIAC who delivered preterm (n=25); and (4) preterm premature rupture of membranes (preterm PROM) with (n=25) and without MIAC (n=26). MIAC was defined as a positive amniotic fluid culture for microorganisms. Amniotic fluid HBD-2 concentrations were determined using a sensitive and specific ELISA. Non-parametric statistics were used for analysis. RESULTS: (1) HBD-2 was detected in all amniotic fluid samples; (2) the concentration of HBD-2 did not change with gestational age from mid-trimester to term (p=0.8); (3) intra-amniotic infection was associated with a significant increase in amniotic fluid concentrations of HBD-2 in both women with preterm labor and intact membranes, and women with preterm PROM (p<0.05 for each comparison); (4) patients with preterm labor and a negative amniotic fluid culture who delivered preterm had a higher median amniotic fluid HBD-2 concentration than those with preterm labor who delivered at term (p=0.001); and (5) among patients with preterm labor without MIAC, those who had intra-amniotic inflammation (amniotic fluid white blood cell count>100 cells per mL) had a higher median amniotic fluid concentration of HBD-2 than those without this condition (p<0.002). CONCLUSION: (1) Amniotic fluid contains HBD-2, a natural antimicrobial peptide, and this may account for some of the antimicrobial activity of amniotic fluid; (2) amniotic fluid HBD-2 concentrations are increased in women with MIAC, regardless of the membrane status (intact membranes or PROM); and (3) we propose that amniotic fluid HBD-2 is part of the innate immune system within the amniotic cavity.     

Value of amniotic fluid neutrophil collagenase concentrations in preterm premature rupture of membranes.

OBJECTIVE: Neutrophils in amniotic fluid are thought to be of fetal origin, and therefore the detection of these cells and/or their products in amniotic fluid may reflect the fetal inflammatory status. We propose that amniotic fluid neutrophil collagenase (matrix metalloproteinase-8) is a useful parameter to predict adverse neonatal outcome, impending preterm labor/delivery, and intrauterine infection in the setting of preterm premature rupture of the membranes. STUDY DESIGN: Amniotic fluid was obtained by transabdominal amniocentesis from 101 patients with preterm premature rupture of the membranes (gestational age, 24-36 weeks). Fluid was cultured for aerobic and anaerobic bacteria and Mycoplasmas. Amniotic fluid analysis included Gram stain, white blood cell count, and determination of interleukin-6 and matrix metalloproteinase-8 concentrations (enzyme-linked immunosorbent assay). RESULTS: Neonates with adverse neonatal outcome were born to mothers with a significantly higher median amniotic fluid matrix metalloproteinase-8 concentration than those without adverse neonatal outcome (median, 54.4 ng/mL; range, 0.82-14,500 ng/mL vs median, 28.9 ng/mL; range, 0.78-2451.8 ng/mL; P <.05, respectively). The higher the amniotic fluid matrix metalloproteinase-8 concentrations, the shorter the interval to delivery (Cox proportional hazards model adjusting for gestational age at delivery; hazard ratio, 1.9; 95% CI, 1.1-3.5; P <.03). Amniotic fluid matrix metalloproteinase-8 concentration was more sensitive than an amniotic fluid white blood cell count and interleukin-6 in the detection of microbiologically proven intra-amniotic infection. CONCLUSION: Increased concentrations of neutrophil collagenase (matrix metalloproteinase-8) in amniotic fluid are associated with intra-amniotic infection, impending preterm delivery, and adverse neonatal outcome in patients with preterm premature rupture of the membranes. Moreover, matrix metalloproteinase-8 in amniotic fluid is a stronger predictor for the duration of pregnancy and intra-amniotic inflammation than interleukin-6 and an amniotic fluid white blood cell count.     

Are amniotic fluid C-reactive protein and glucose levels, and white blood cell counts at the time of genetic amniocentesis related with preterm delivery?

OBJECTIVE: To compare women with spontaneous preterm delivery before 37 weeks and women who delivered at term with respect to amniotic fluid C-reactive protein (CRP), glucose levels, and white blood cell counts at the time of genetic amniocentesis. STUDY DESIGN: The study was conducted on 216 pregnant women who underwent genetic amniocentesis between the 15th and 18th weeks of gestation at Baskent University Obstetrics and Gynecology Department. All patients were followed until delivery for the occurrence of pregnancy complication. Indications for amniocentesis included abnormal triple test results showing increased risk for Down's syndrome, advanced maternal age and sonographic findings indicative for chromosomal abnormalities. The samples were carried immediately to the laboratory for cytogenetic and biochemical examination. Women with spontaneous preterm delivery before 37 weeks (n = 20) and those who delivered at term (n = 196) were compared with respect to some maternal and infant characteristics, amniotic fluid C-reactive protein, glucose levels, and amniotic fluid white blood cell counts. RESULTS: During the study period 244 patients underwent amniocentesis. A chromosomal abnormality was present in 11 patients. 1 patient had a spontaneous pregnancy loss within 3 weeks after the procedure and 16 patients were delivered for fetal or maternal indications (preeclampsia, fetal growth restriction, placenta previa). The remaining 216 women were included in the study and investigated for the risk of preterm delivery. The prevalence of spontaneous preterm delivery before 37 weeks was 9.3% (20/216). There were no significant differences between the preterm delivery and the term delivery groups with respect to C-reactive protein levels and white blood cell counts. Mean amniotic glucose levels were significantly lower in the preterm delivery group (P<0.05). Amniotic fluid glucose levels of < or = 46 mg/dL had a sensitivity of 100% and NPV of 100%. CONCLUSION: Amniotic fluid glucose levels at the time of genetic amniocentesis are lower in women with spontaneous preterm delivery before 37 weeks compared to those who delivered at term. Amniotic fluid glucose levels of < or = 46 mg/dL at the time of genetic amniocentesis may be more sensitive, cheaper and have higher negative predictive value than C-reactive protein levels and white blood cell counts for the prediction of patients in spontaneous preterm labor. The greatest benefit of amniotic fluid glucose testing might be when the physician judges the patient to be at low risk for preterm delivery.     

Elevated amniotic fluid C-reactive protein at the time of genetic amniocentesis is a marker for preterm delivery

OBJECTIVE: A pre-existing intrauterine inflammation in the first half of gestation has been proposed as a possible condition that leads to preterm delivery. Indeed, elevated levels of inflammatory mediators (eg, interleukin-6, tumor necrosis factor) in midtrimester amniotic fluid have been found in cases of preterm delivery and/or spontaneous abortion. The objective of this study was to investigate whether the amniotic fluid C-reactive protein level at the time of genetic amniocentesis is a marker for spontaneous preterm delivery before 34 and 37 weeks of gestation. STUDY DESIGN: Women who underwent genetic amniocentesis between 15 and 18 weeks of gestation with (1) singleton gestation, (2) uneventful pregnancy course before the amniocentesis, and (3) absence of fetal abnormalities were included in the study. Patients with abnormal karyotype were excluded. C-reactive protein concentration was measured in amniotic fluid and in maternal blood immediately after genetic amniocentesis. All patients were followed until delivery for the occurrence of pregnancy complications. Nonparametric tests and receiver-operating characteristic curve analysis were used for statistical purposes. RESULTS: The prevalence of spontaneous preterm delivery before 34 and 37 weeks was 3.3% (10 of 306 pregnancies) and 8.5% (26 of 306 pregnancies), respectively. Women with preterm delivery at <37 weeks had a higher median (range) of amniotic fluid C-reactive protein concentration than those women who delivered at term (median, 113.3 ng/mL [range, 16-623 ng/mL] vs median, 57.8 ng/mL [range, 0-808.9 ng/mL]; P <.005). Women with preterm delivery at <34 weeks had a higher median (range) amniotic fluid C-reactive protein concentration than those women who delivered at term (median, 183.8 ng/mL [range, 46.5-447 ng/mL] vs median, 57.8 ng/mL [range, 0-808.9 ng/mL]; P <.005]. No correlation was found between amniotic fluid C-reactive protein and maternal blood C-reactive protein concentrations. No relationship was found between maternal blood C-reactive protein concentration and preterm delivery before either 34 or 37 weeks. Amniotic fluid C-reactive protein concentration of >110 ng/mL had a sensitivity of 80.8% and a specificity of 69.5% in the prediction of spontaneous preterm delivery at <34 weeks. CONCLUSION: This study supports the theory that a subclinical intrauterine/fetal inflammatory process early in gestation may be important for the occurrence of preterm delivery in the second half of gestation.     

The clinical significance of eosinophils in the amniotic fluid in preterm labor

Objective.?White blood cells are not traditionally considered to be normally present in amniotic fluid. This study was conducted after the observation that a patient with preterm labor and intact membranes had eosinophils as a predominant cell in the amniotic fluid, and had an episode of asthma during the index pregnancy. The goal of this study was to determine whether women presenting with preterm labor with eosinophils in the amniotic fluid had a different outcome than those without eosinophils as the predominant white blood cell in the amniotic cavity.

Methods.?This retrospective case–control study included women who presented with preterm labor and intact membranes between 24 and 34 weeks of gestation. Patients 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. Cytologic studies included amniotic fluid white blood cell count and differential, which was performed on cytocentrifuged specimens. Patients with microbial invasion of the amniotic cavity and/or an amniotic fluid white blood cell count >20 cells/mm³ were excluded from the study. Cases were defined as women in whom the differential contained >20% of eosinophils. Controls were selected among women with an amniotic fluid eosinophil count ≤20% and matched for gestational age at amniocentesis. The analysis was conducted with non-parametric statistics.

Results.?The study population consisted of 10 cases and 50 controls. Gestational age and cervical dilatation at admission were similar in both groups. Cases had a lower gestational age at delivery than controls [34.6 weeks, inter-quartile range (IQR) 32–37.3 weeks vs. 38.0 weeks, IQR 35–40 weeks, respectively; p?=?0.018]. The prevalence of preterm delivery ≤35 weeks was higher among patients who had >20% eosinophils than in the control group [50% (5/10) vs. 18% (9/50), respectively; p?=?0.029]. Similar results were observed for delivery at <37 weeks [cases: 70% (7/10) vs. controls: 36% (18/50); p?=?0.046].

Conclusions.?Women with preterm labor and intact membranes who have a large proportion of eosinophils in the amniotic fluid are at an increased risk for spontaneous preterm delivery. These patients may have had an episode of preterm labor related to a type I hypersensitivity reaction.     

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

OBJECTIVE: Matrix metalloproteinases are enzymes capable of degrading extracellular matrix components. Matrilysin (matrix metalloproteinase 7), a novel member of this family, degrades fibronectin and proteoglycans. The objective of this study was to determine whether parturition (either term or preterm), premature rupture of the membranes, and microbial invasion of the amniotic cavity are associated with changes in the amniotic fluid concentration of matrilysin. STUDY DESIGN: A cross-sectional study was conducted with 275 women in the following categories: (1) second trimester, (2) term not in labor, (3) term in labor, (4) term with microbial invasion of the amniotic cavity, (5) preterm labor with intact membranes without microbial invasion of the amniotic cavity who delivered at term, (6) preterm labor without microbial invasion of the amniotic cavity who delivered preterm, (7) preterm labor with microbial invasion of the amniotic cavity, (8) preterm premature rupture of membranes with and without microbial invasion of the amniotic cavity, and (9) term premature rupture of membranes not in labor and without microbial invasion of the amniotic cavity. Matrilysin concentrations were measured with a sensitive specific immunoassay that was validated for amniotic fluid. RESULTS: Matrilysin was detectable in 97.4% (268/275) of the samples. The concentration of matrilysin increased with advancing gestational age (r = 0.8; P <.001). Parturition at term was not associated with a significant increase in amniotic fluid concentration of matrilysin. Preterm parturition in the absence of microbial invasion of the amniotic cavity was associated with a significant increase in amniotic fluid concentration of matrilysin (preterm labor with preterm delivery: median, 1.7 ng/mL; range, 0.45-21.6 mg/mL; vs preterm labor with term delivery: median, 1.2 ng/mL; range, 0.17-42. 1 ng/mL; P <.05). Premature rupture of membranes without microbial invasion of the amniotic cavity (either term or preterm) was not associated with a significant change in the amniotic fluid matrilysin concentration. Intra-amniotic infection was associated with a significant increase in amniotic fluid matrilysin among both patients with preterm labor and patients with preterm premature rupture of membranes (preterm labor with microbial invasion of the amniotic cavity: median, 3.2 ng/mL; range, 0.16-21.9 ng/mL; vs preterm labor and delivery without microbial invasion of the amniotic cavity: median, 1.7 ng/mL; range, 0.45-21.6 ng/mL; vs preterm labor with term delivery: median, 1.2 ng/mL; range, 0.17-42. 1 ng/mL; P <.01 for each comparison; and preterm premature rupture of membranes without microbial invasion of the amniotic cavity: median, 1.7 ng/mL; range, 0.29-13.9 ng/mL; vs preterm premature rupture of membranes with microbial invasion of the amniotic cavity: median, 3.6 ng/mL; range, 0.59-20.3 ng/mL; P <.01). CONCLUSION: Matrilysin is a physiologic constituent of amniotic fluid, and its concentration increases with advancing gestational age. Microbial invasion of the amniotic cavity in preterm gestations was associated with a significant increase in amniotic fluid concentration of matrilysin. Matrilysin therefore may play a role in the host defense mechanism.     

Lactoferrin in intrauterine infection, human parturition, and rupture of fetal membranes

OBJECTIVE: Lactoferrin is an iron-binding protein with antimicrobial properties. This study was undertaken to determine whether amniotic fluid concentrations of this protein change with gestational age, infection, labor, and rupture of membranes. STUDY DESIGN: This cross-sectional study included women who underwent transabdominal amniocentesis (n = 268) in the following groups: (1) mid trimester of pregnancy; (2) preterm labor who delivered at term, preterm labor who delivered preterm with intra-amniotic infection, and preterm labor who delivered preterm without intra-amniotic infection; (3) preterm premature rupture of membranes in the presence or absence of intra-amniotic infection; (4) term with intact membranes not in labor, in labor, and in labor with intra-amniotic infection; and (5) premature rupture of membranes at term not in labor. In addition, lactoferrin concentrations were determined in maternal plasma and cord blood of patients at term not in labor. Lactoferrin concentration was measured with an immunoassay. RESULTS: (1) Lactoferrin was detectable in 85.4% (229/268) of amniotic fluid samples, not detectable in all fluid obtained in the mid trimester, and detectable in all maternal and cord plasma samples. (2) The concentration of lactoferrin increased with advancing gestational age (r = 0.68; P <.0001). (3) Intra-amniotic infection was associated with significant increases in amniotic fluid lactoferrin concentrations in patients with preterm labor (no intra-amniotic infection median, 1641.2 ng/mL; range, <1.24-35,090.0 ng/mL; vs intra-amniotic infection median, 3833.6 ng/mL; range, 746.0-47,020.0 ng/mL; P <.001), term labor (no intra-amniotic infection median, 2085.8 ng/mL; range, 425.0-23,230.0 ng/mL; vs intra-amniotic infection median, 5627.0 ng/mL; range, <1.24-19,220.0 ng/mL; P <. 001), and preterm premature rupture of membranes (no intra-amniotic infection median, 2190 ng/mL; range, <1.24-7456.1 ng/mL; vs intra-amniotic infection median, 3449.3 ng/mL; range, <1.24-83,600. 0; P <.01). (4) Spontaneous labor at term but not preterm was associated with a significant decrease in amniotic fluid lactoferrin concentration (P <.05). (5) Spontaneous term parturition was associated with a significant increase in umbilical cord plasma lactoferrin concentration (P <.005). CONCLUSION: (1) Intra-amniotic infection was consistently associated with dramatically increased concentrations of lactoferrin in amniotic fluid. (2) Term parturition was associated with a significant increase in lactoferrin concentration in the fetal compartment (umbilical cord blood) and a decrease in the amniotic compartment. We propose that lactoferrin is part of the repertoire of host defense mechanisms against intra-amniotic infection.     

Maternal serum and amniotic fluid IL-1 alpha, IL-1 beta, IL-6 and IL-8 levels in preterm and term labor complicated by PROM

Cytokines may be implicated in the pathophysiologic mechanisms of preterm and term labor. Many studies indicate cytokines as predictors of preterm delivery and explain partially mechanism of preterm uterine contractions. Complicated relations between mediators in systemic fluids of a fetomaternal unit require further explorations. The right diagnosis and management require better understanding of these relationships. OBJECTIVES: The comparison of IL-1 alpha, IL-1 beta, IL-6 and IL-8 levels in maternal serum and amniotic fluid in term and preterm labor complicated by PROM. MATERIAL AND METHODS: In 44 patients in premature labor with PROM (group I) and 33 patients in labor at term with PROM (group II) cytokines levels were estimated one time in amniotic fluid: just after PROM, and two times in maternal serum: just after PROM and during labor. RESULTS: Amniotic fluid cytokines levels were significantly higher in group I than in group II. Maternal serum cytokines concentrations of IL-1 alpha and IL-1 beta in group I were significantly higher than in group II. IL-6 level was significantly higher in group II than in group I. In both groups maternal serum IL-6 levels during labor significantly increased in comparison to IL-6 levels just after PROM. No correlations between amniotic fluid and maternal serum cytokine levels at PROM were observed. CONCLUSIONS: Higher amniotic fluid cytokines levels in patients with preterm labor complicated by PROM than in labor at term with PROM indicate possible differences between PROM mechanisms in preterm and term labor. The increase of IL-6 level during labor can be related with the possible role of this cytokine in the immunological mechanism of the labor beginning. No relationships between amniotic fluid and maternal serum levels of investigated cytokines in PROM suggest the presence of the barrier stopped cytokines transfer by the placenta and the complete separation of these two compartments.     

A rapid interleukin-6 bedside test for the identification of intra-amniotic inflammation in preterm labor with intact membranes

Objective: Preterm birth is associated with 5–18% of pregnancies and is the leading cause of neonatal morbidity and mortality. Amniotic fluid (AF) interleukin-6 (IL-6) is a key cytokine for the identification of intra-amniotic inflammation, and patients with an elevated AF IL-6 are at risk for impending preterm delivery. However, results of the conventional method of measurement (enzyme-linked immunosorbent assay; ELISA) are usually not available in time to inform care. The objective of this study was to determine whether a point of care (POC) test or lateral-flow-based immunoassay for measurement of AF IL-6 concentrations can identify patients with intra-amniotic inflammation and/or infection and those destined to deliver spontaneously before term among women with preterm labor and intact membranes.

Methods: One-hundred thirty-six women with singleton pregnancies who presented with symptoms of preterm labor and underwent amniocentesis were included in this study. Amniocentesis was performed at the time of diagnosis of preterm labor. AF Gram stain and AF white blood cell counts were determined. Microbial invasion of the amniotic cavity (MIAC) was defined according to the results of AF culture (aerobic and anaerobic as well as genital mycoplasmas). AF IL-6 concentrations were determined by both lateral flow-based immunoassay and ELISA. The primary outcome was intra-amniotic inflammation, defined as AF ELISA IL-6?≥?2600?pg/ml.

Results: (1) AF IL-6 concentrations determined by a POC test have high sensitivity (93%), specificity (91%) and a positive likelihood ratio of 10 for the identification of intra-amniotic inflammation by using a threshold of 745?pg/ml; (2) the POC test and ELISA for IL-6 perform similarly in the identification of MIAC, acute inflammatory lesions of placenta and patients at risk of impending spontaneous preterm delivery.

Conclusion: A POC AF IL-6 test can identify intra-amniotic inflammation in women who present with preterm labor and intact membranes and those who will subsequently deliver spontaneously before 34 weeks of gestation. Results can be available within 20?min – this has important clinical implications and opens avenues for early diagnosis as well as treatment of intra-amniotic inflammation/infection.     

Amniotic fluid matrix metalloproteinase-8 in preterm labor with intact membranes.

OBJECTIVE: Intra-amniotic inflammation is a major determinant of maternal and neonatal outcome in patients with preterm labor. Matrix metalloproteinase-8 is a sensitive marker of inflammation in body fluids. This study was conducted to examine the value of amniotic fluid matrix metalloproteinase-8 determinations in patients with preterm labor and intact membranes. STUDY DESIGN: Amniotic fluid was obtained by transabdominal amniocentesis from 371 patients with preterm labor. Fluid was cultured for aerobic and anaerobic bacteria and Mycoplasmas. Amniotic fluid analysis included Gram stain examination, white blood cell count, and matrix metalloproteinase-8 (enzyme-linked immunosorbent assay) determination. Nonparametric statistics were used for analysis. RESULTS: The rate of preterm delivery was 54% (200/371) and that of intra-amniotic infection was 9.2% (34/371). The median amniotic fluid matrix metalloproteinase-8 concentration was more than 50-fold higher in patients with intra-amniotic infection than in patients with no intra-amniotic infection (median, 605.6 ng/mL; range, 0.65-15,000 ng/mL vs median, 10.6 ng/mL; range, <0.06-16,600 ng/mL, respectively; P <.0001). The matrix metalloproteinase-8 amniotic fluid concentrations were significantly higher in patients who delivered preterm than in patients who delivered at term (median, 19.5 ng/mL; range, <0.06-16,600 ng/mL vs median, 2.1 ng/mL; range, <0.06-500 ng/mL, respectively; P <.001). After exclusion of patients with intra-amniotic infection, patients who delivered preterm had a significantly higher median amniotic fluid matrix metalloproteinase-8 than patients who delivered at term (P <.05). An amniotic fluid matrix metalloproteinase-8 level of >30 ng/mL was an independent predictor for the occurrence of neonatal morbidity (odds ratio, 3.4; 95% CI, 1.9-5.8; P <.01). CONCLUSION: Increased amniotic fluid matrix metalloproteinase-8 concentrations identify patients at risk for intra-amniotic infection, impending preterm delivery, and adverse neonatal outcome.