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.     

Comparison of rapid MMP-8 and interleukin-6 point-of-care tests to identify intra-amniotic inflammation/infection and impending preterm delivery in patients with preterm labor and intact membranes*

Objective: Among patients presenting with preterm labor and intact membranes, those with intra-amniotic inflammation have adverse obstetrical and neonatal outcomes. The diagnosis of intra-amniotic inflammation can easily be made by detecting an elevated concentration of the cytokine interleukin (IL)-6 or the enzyme neutrophil collagenase, also known as matrix metalloproteinase (MMP)-8. The diagnostic performances of MMP-8 and IL-6 enzyme-linked immunosorbent assay tests are similar. Recently, a rapid test has become available for point-of-care determination of either MMP-8 or IL-6. The objectives of this study were to compare the diagnostic indices and predictive values between the rapid MMP-8 and IL-6 tests for the identification of intra-amniotic inflammation in patients with preterm labor and intact membranes.

Materials and methods: We performed a retrospective cohort study including 124 women with singleton pregnancies who presented with symptoms of preterm labor and underwent transabdominal amniocentesis for the evaluation of microbial invasion of the amniotic cavity (MIAC). MIAC was defined according to amniotic fluid culture results (aerobic and anaerobic bacteria as well as genital Mycoplasmas). Amniotic fluid white blood cell (WBC) counts were determined using a hemocytometer chamber. An elevated amniotic fluid MMP-8 concentration was assessed using Yoon’s MMP-8 Check^® (cutoff: 10?ng/mL). An elevated amniotic fluid IL-6 concentration was scored when there was a positive result for the lateral flow-based immunoassay (cutoff: ≥745?pg/mL and ≥1000?pg/mL). In order to objectively compare rapid MMP-8 and rapid IL-6 tests to identify intra-amniotic inflammation, an amniotic fluid WBC count of ≥50 cells/mm³ was used to define intra-amniotic inflammation.

Results: (1) The rapid tests had the same sensitivity for the detection of intra-amniotic inflammation [85.7% (18/21) for all]; (2) the specificity of the rapid MMP-8 test was higher than that of the rapid IL-6 test (cutoff: 745?pg/mL) for the identification of intra-amniotic inflammation [72.8% (75/103) vs. 64.1% (66/103); p?Conclusion: We conclude that the rapid MMP-8 test has a better specificity than the rapid IL-6 (cutoff: 745?pg/mL) assay for the detection of intra-amniotic infection. Moreover, we observed that among patients who were not identified as having intra-amniotic infection or inflammation by the standard cultivation technique and amniotic fluid WBC count, those who had a positive MMP-8 rapid test delivered preterm and had acute histologic chorioamnionitis.     

Gender differences in amniotic fluid cytokine levels

Objective: Placental trophoblast invasion and amniotic fluid cytokine receptor levels have been reported to vary with fetal gender. We investigated whether fetal gender affects amniotic fluid levels of the inflammatory cytokines interleukin (IL)-6 and IL-10 and the pro-angiogenesis cytokine angiogenin.

Methods: Specimens from singleton gestations undergoing mid-trimester amniocentesis for genetic indications were used. Inclusion criteria were (1) outcome information available, (2) no structural or chromosomal anomaly and (3) no conditions associated with preterm delivery. Amniotic fluid IL-6, IL-10 and angiogenin levels were measured by immunoassay. Statistical analysis included the Mann–Whitney U test and Fisher's exact test with p?<?0.05 indicating significance.

Results: A total of 74 samples were analyzed. Angiogenin levels were significantly lower in amniotic fluid samples from pregnancies with a male than with a female fetus (median (range): 22.2 (5.9–66.4) vs. 32.0 (11.4–159.2) ng/ml, p?=?0.007), in contrast to no differences in amniotic fluid IL-6 and IL-10 levels (p?=?0.4 and p?=?0.1, respectively). In pregnancies with male fetuses delivering preterm (<?37 weeks), angiogenin was also detected at lower levels (p?=?0.02). There were no gender differences with respect to race, nulliparity or maternal age.

Conclusion: Angiogenin levels, but not IL-6 or IL-10 levels, are significantly lower in second-trimester amniotic fluid of women with male compared with female fetuses, including those women delivering preterm.     

Procalcitonin in amniotic fluid at the time of genetic amniocentesis and preterm delivery

Purpose: Procalcitonin (PCT) is an acute-phase protein that has been infrequently studied in amniotic fluid. We sought to determine if PCT levels measured in amniotic fluid samples at the time of genetic amniocentesis are predictive of preterm delivery.

Materials and methods: A retrospective cohort study was performed on all women presenting for genetic amniocentesis between 15–23 weeks of pregnancy at our institution from 2011 to 2013 with stored amniotic fluid samples. PCT protein levels were measured in the samples by enzyme-linked immunosorbent assay (ELISA). PCT levels in women who delivered less than 37 weeks versus those who delivered at or after 37 week were compared. Mann–Whitney test was used.

Results: Eighty-seven samples were available for analysis and of these eight (9.2%) were from patients who delivered preterm. Sixty-two (70%) had PCT levels below the lower limit of quantification, which was 25?pg/mL. Median PCT levels did not differ between the preterm and term group [20.4?pg/mL (range 0–82.8) and 20.2?pg/mL (range 0–198.4), respectively, p?=?.95].

Conclusion: In asymptomatic women undergoing genetic amniocentesis in this cohort, procalcitonin levels were low to undetectable and did not correlate with risk of subsequent preterm birth.     

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.     

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.     

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.     

The use of the polymerase chain reaction to detect bacteria in amniotic fluid in pregnancies complicated by preterm labor

OBJECTIVES: The purpose of this investigation was to determine the feasibility of using the polymerase chain reaction to detect bacteria in amniotic fluid and to compare pregnancy outcomes in subsets of women categorized by amniotic fluid culture, polymerase chain reaction, and interleukin-6 findings. STUDY DESIGN: Amniotic fluid from 54 pregnancies with preterm labor and no clinical evidence of intraamniotic infection was evaluated with use of the polymerase chain reaction, interleukin-6, and bacterial culture. Gestational age, newborn weight, and time between amniocentesis and delivery were compared between subsets of women categorized by these tests. RESULTS: With use of the polymerase chain reaction <100 bacteria per milliliter could be detected in amniotic fluid. A total of 55.5% of the amniotic fluid samples were polymerase chain reaction positive, whereas 9.2% of culture results were positive. Birth weights and gestational age at delivery were less and time from amniocentesis to delivery was shorter in the polymerase chain reaction–positive group (p < 0.05). Nine samples (15%) had elevated interleukin-6 concentrations; of these, six were polymerase chain reaction positive. CONCLUSIONS: The polymerase chain reaction is a sensitive means of detecting bacteria in amniotic fluid. These results provide further evidence of an association between preterm delivery and intraamniotic infection. Not all amniotic fluid samples with elevated interleukin-6 levels have bacteria detectable by the polymerase chain reaction. We anticipate that the polymerase chain reaction will provide another avenue for the detection of bacteria in amniotic fluid.(Am J Obstet Gynecol 1997;177:1471-7)     

Amniotic fluid heat shock protein 70 concentration in histologic chorioamnionitis,term and preterm parturition

Objective. Heat shock protein (HSP) 70, a conserved member of the stress protein family, is produced in almost all cell types in response to a wide range of stressful stimuli, and its production has a survival value. Evidence suggests that extracellular HSP70 is involved in the activation of the innate and adaptive immune response. Furthermore, increased mRNA expression of HSP70 has been observed in human fetal membranes following endotoxin stimulation. This study was conducted to determine the changes in amniotic fluid HSP70 concentrations during pregnancy, term and preterm parturition, intra-amniotic infection (IAI), and histologic chorioamnionitis.

Study design. A cross-sectional study was conducted in 376 pregnant women in the following groups: (1) women with a normal pregnancy who were classified into the following categories: (a) women in the mid-trimester (14–18 weeks) who underwent amniocentesis for genetic indications and delivered normal infants at term (n=72); (b) women at term not in labor (n = 23); and (c) those at term in labor (n = 48). (2) Women with spontaneous preterm labor and intact membranes who were subdivided into the following categories: (a) preterm labor who delivered at term without IAI (n = 42); (b) preterm labor who delivered preterm without IAI (n = 57); and (c) preterm labor and delivery with IAI (n = 30). (3) Women with preterm prelabor rupture of membranes (PROM) with (n = 50) and without (n = 54) IAI. Among patients with preterm labor with intact membranes and preterm PROM who delivered within 72 hours of amniocentesis, placenta, umbilical cord, and chorioamniotic membranes were collected and assessed for the presence or absence of acute inflammatory lesions in the extraplacental membranes (histologic chorioamnionitis) and/or umbilical cords (funisitis). HSP70 concentrations in amniotic fluid were determined using a sensitive and specific immunoassay. Non-parametric statistics were used for analysis. A p value of <0.05 was considered statistically significant.

Results. Immunoreactive HSP70 was detected in 88% (332/376) of amniotic fluid samples. The median amniotic fluid HSP70 concentration was significantly higher in women at term without labor than in those in the mid-trimester (term no labor: median 34.9 ng/mL, range 0–78.1 ng/mL vs. mid-trimester; median 6.6 ng/mL, range 0–20.8 ng/mL; p<0.001). Among patients with spontaneous preterm labor and preterm PROM, those with IAI had a significantly higher median amniotic fluid HSP70 concentration than those without IAI (preterm labor with IAI: median 82.9 ng/mL, range 0–500 ng/mL vs. preterm labor without IAI: median 41.7 ng/mL, range 0–244 ng/mL; p = 0.001; preterm PROM with IAI: median 86.5 ng/mL, range 0–428 ng/mL vs. preterm PROM without IAI: median 55.9 ng/mL, range 14.9–299.9 ng/mL; p = 0.007). There was no significant difference in the median amniotic fluid HSP70 concentration between patients with preterm labor who delivered preterm without IAI and those who delivered at term (p = 0.6). However, among patients with preterm labor without IAI, there was an inverse relationship between amniotic fluid concentration of HSP70 and the amniocentesis-to-spontaneous delivery interval (Spearman's Rho = ?0.26; p = 0.02). Patients with histologic chorioamnionitis/funisitis had a significantly higher median amniotic fluid HSP70 concentration than those without inflammation (inflammation: median 108.7 ng/mL, range 0–500 ng/mL vs. without inflammation: median 67.9 ng/mL, range 7.1–299.9 ng/mL; p = 0.02). Women at term in labor had a median amniotic fluid concentration of HSP70 significantly higher than those not in labor (term in labor: median 60.7 ng/mL, range 0–359.9 ng/mL vs. term not in labor: median 34.9 ng/mL, range 0–78.1 ng/mL; p = 0.02).

Conclusions. Intra-amniotic infection, histologic chorioamnionitis, and term parturition are associated with elevated amniotic fluid HSP70 concentrations. HSP70 plays a role in the host defense mechanism by activating the innate arm of the immune response in women with intrauterine infection. The mechanisms of preterm and term parturition in humans may involve extracellular HSP70.     

Interleukin-6 and Mycoplasma hominis as markers of preterm birth and related brain damage: Our experience

Objective.?The aim of this study is to investigate whether a high concentration of interleukin-6 (IL)-6 in the amniotic fluid is associated to a higher risk of preterm delivery, premature rupture of the membranes (PROM), and periventricular leucomalacia (PVL) in preterm infants; we have further investigated whether the levels of IL-6 are related to the presence of vaginal infection by mycoplasms.

Methods. One hundred eight patients were screened by vaginal swab, sonography, amniocentesis, and dosage of IL-6 in the amniotic fluid during the second trimester of pregnancy.

Results.?High levels of IL-6 and vaginal mycoplasms are related to preterm birth and PROM. We had no case of PLV.

Conclusion.?In order to achieve a good therapeutic purpose and get to an efficient strategy, the patients have to be elected by a number of criteria, which may include anamnesis elements, vaginal swab, then cytokines dosage in selected women, thus excluding the low-risk cases. Further studies are expected in order to plan guidelines including the dosage of ILs and principally of IL-6 as a main marker of preterm birth, above all during the second trimester.     

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.     

Evidence of the involvement of caspase-1 under physiologic and pathologic cellular stress during human pregnancy: A link between the inflammasome and parturition

Objective. Caspase-1 is a component of the NALP3 inflammasome, a cytosolic multiprotein complex that mediates the processing of pro-inflammatory caspases and cytokines. The inflammasome represents the first line of defense against cellular stress and is a crucial component of innate immunity. Caspase-1 is the enzyme responsible for the cleavage and activation of interleukin (IL)-1β, which is a potent pro-inflammatory cytokine, and plays a central role in the mechanisms leading to labor (preterm and term) particularly in the context of intrauterine infection/inflammation. In addition, caspase-1 cleaves IL-18 and IL-33. The objectives of this study were to determine whether there is a relationship between amniotic fluid concentrations of caspase-1 and gestational age, parturition (term and preterm), and intra-amniotic infection/inflammation (IAI).

Study design. A cross-sectional study was conducted including 143 pregnant women in the following groups: (1) mid-trimester of pregnancy (n = 18); (2) term not in labor (n = 25); (3) term in labor (n = 28); (4) preterm labor (PTL) who delivered at term (n = 23); (5) PTL without IAI who delivered preterm (n = 32); (6) PTL with IAI who delivered preterm neonates (n = 17). Caspase-1 concentrations in amniotic fluid were determined by a specific and sensitive immunoassay. Non-parametric statistics were used for analysis.

Results. (1) Caspase-1 was detected in amniotic fluid of women at term, but in none of the mid-trimester samples. (2) Patients in labor at term had a significantly higher median amniotic fluid concentration of caspase-1 than women at term not in labor (term in labor: 10.5 pg/mL, range 0.0–666.0 vs. term not in labor: 5.99 pg/mL, range 0.0–237.4; p < 0.05). (3) Among patients with spontaneous PTL, those with IAI (median 41.4 pg/mL, range 0.0–515.0) had a significantly higher median amniotic fluid caspase-1 concentration than those without IAI who delivered preterm (median 0.0 pg/mL, range 0.0–78.4) and than those who delivered at term (median 0.0 pg/mL, range 0.0–199.5); p < 0.001 for both comparisons.

Conclusions. (1) The presence and concentration of caspase-1 in the amniotic fluid varies as a function of gestational age. (2) Women with spontaneous labor at term had a higher median caspase-1 amniotic fluid concentration than women at term without labor. This suggests that the inflammasome may be activated in spontaneous parturition at term. Since most women with labor do not have intra-amniotic infection, we propose that cellular stress during labor accounts for activation of the inflammasome. (3) Preterm labor associated with infection/inflammation was also associated with a high concentration of caspase-1, suggesting that infection may induce caspase-1 production and activation of the inflammasome. (4) The sequential activation of the inflammasome and caspase-1, leading to interleukin-1β processing and secretion, is a candidate pathway leading to the activation of the common pathway of parturition.     

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.     

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.     

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 placenta growth factor levels in the early second-trimester amniotic fluid are associated with preterm delivery

Objective: The purpose of this study was to determine how angiogenesis-related factors correlate with preterm delivery.

Methods: A cohort of 382 pregnant women undergoing early second-trimester genetic amniocentesis was enrolled and followed-up until delivery, and the amniotic fluid was collected and stored as a nested case-control study. Cases with preterm delivery (n?=?31) were compared with matched controls with term delivery (n?=?62). The amniotic fluid concentrations of placenta growth factor (PlGF), angiogenins, angiopoietin-2, soluble fms-like tyrosine kinase and soluble endoglin were determined using enzyme-linked immunosorbent assays.

Results: Women who delivered preterm had a higher amniotic PlGF concentration compared with the control group (median 12.6 pg/ml versus 6.1 pg/ml; p=0.027). Other angiogenesis-related factors did not show any differences between case and control groups. The odds ratio for preterm delivery based on amniotic fluid PlGF was 1.031 (95% confidence interval: 1.002–1.061; p=0.035). Additionally, when the cases were subdivided into early preterm, late preterm and term groups, PlGF values between the early preterm and term delivery groups were significantly different (median 16.6 pg/ml versus 6.1 pg/ml; Bonferroni-adjusted p=0.018).

Conclusion: Amniotic fluid PlGF levels in the early second trimester of pregnancy are associated with preterm delivery.     

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.     

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.