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

Proteomic analysis of amniotic fluid to identify potential targets predicting preterm delivery

Preterm delivery is a common complication of pregnancy which leads to significant neonatal mortality and morbidity. Identifying predictive markers linked to spontaneous preterm delivery (SPTD) is important for effective treatment and prevention of PTD. To explore potential biomarkers related to SPTD, we performed proteomics analysis in amniotic fluid (AF). In total, we enrolled 30 pregnant women with singleton gestation who underwent clinically indicated amniocentesis at 15-24 weeks of gestation. LC-MS analysis was used to analyze the AF samples of 10 women with SPTD < 34 weeks after cervix cerclage (Preterm group), 10 women with term delivery (TD) ≥ 34 weeks after cervix cerclage (Term group), and 10 women who delivered at term (Normal group). ELISA validation was performed for candidate proteins in a second independent cohort. As a result, we identified 44 differentially expressed proteins (DEPs, P < 0.05) via proteomic analysis, and based on that, 9 primary pathways were also determined in SPTD. Results of the ELISA assay confirmed that the increased concentration of Serpin A1, decreased concentrations of Renin and IGFBP4 were significantly associated with SPTD at ≤34 weeks.

Identifying potential biomarkers related to pre-term delivery by proteomic analysis of amniotic fluid

We sought to identify biomarkers in the amniotic fluid (AF) and specific signaling pathways related to spontaneous preterm delivery (SPTD, < 34 weeks) in women with preterm labor (PTL) without intra-uterine infection/inflammation (IUI). This was a retrospective cohort study of a total of 139 PTL women with singleton gestation (24 + 0 to 32 + 6 weeks) who underwent amniocentesis and who displayed no evidence of IUI. A nested case-control was conducted using pooled AF samples (n = 20) analyzed via label-free liquid chromatography-tandem mass spectrometry. In the total cohort, an ELISA validation study was performed for seven candidate proteins of interest. Proteomic analysis identified 77 differentially expressed proteins (DEPs, P < 0.05) in the AF from SPTD cases compared to term delivery controls. ELISA validation confirmed that women who had an SPTD before 34 weeks had significantly independently lower levels of VEGFR-1 and higher levels of lipocalin-2 and the Fc fragment of IgG binding protein in the AF. Five principle pathways associated with the 77 DEPs were identified, including glycolysis, gluconeogenesis, and iron homeostasis. The proteomic analysis data of AFs from women with PTL identified several novel biomarkers and specific protein pathways related to SPTD in the absence of IUI.

The association between selected mid-trimester amniotic fluid candidate proteins and spontaneous preterm delivery

Objective: The aim of this study was to explore inflammatory response and identify early potential biomarkers in mid-trimester amniotic fluid associated with subsequent spontaneous preterm delivery (PTD).Methods: A cohort study was performed at Sahlgrenska University Hospital/Östra, Gothenburg, Sweden, between 2008 and 2010. Amniotic fluid was collected from consecutive women undergoing mid-trimester transabdominal genetic amniocentesis at 14-19 gestational weeks. Clinical data and delivery outcome variables were obtained from medical records. The analysis included 19 women with spontaneous PTD and 118 women who delivered at term. A panel of 26 candidate proteins was analyzed using Luminex xMAP technology. Candidate protein concentrations were analyzed with ANCOVA and adjusted for plate effects.Results: The median gestational age at delivery was 35 + 3 weeks in women with spontaneous PTD and 40 + 0 weeks in women who delivered at term. Nominally significantly lower amniotic fluid levels of adiponectin (PTD: median 130,695 pg/mL (IQR 71,852-199,414) vs term: median 185,329 pg/mL (IQR (135,815-290,532)), granulocyte-macrophage colony stimulating factor (PTD: median 137 pg/mL (IQR 74-156) vs term: median 176 pg/mL (IQR 111-262)), and macrophage migration inhibitory factor (PTD: median 3025 pg/mL (IQR 1885-3891) vs term: median 3400 pg/mL (IQR 2181-5231)) were observed in the spontaneous PTD group, compared with the term delivery group, after adjusting for plate effects. No significant differences remained after Bonferroni correction for multiple comparisons.Conclusions: Our results are important in the process of determining the etiology behind spontaneous PTD but due to the non-significance after Bonferroni correction, the results should be interpreted with caution. Further analyses of larger sample size will be required to determine whether these results are cogent and to examine whether microbial invasion of the amniotic cavity or intra-amniotic inflammation occurs in asymptomatic women in the mid-trimester with subsequent spontaneous PTD.

Amniotic fluid pentraxins: Potential early markers for identifying intra-amniotic inflammatory complications in preterm pre-labor rupture of membranes

In this study, pentraxin 3 (PTX3), C-reactive protein (CRP), and serum amyloid P component (SAP) concentrations in the amniotic fluid of women with preterm pre-labor rupture of membranes (PPROM) were evaluated based on evidence of microbial invasion of the amniotic cavity (MIAC), intra-amniotic inflammation (IAI), and microbial-associated IAI. A total of 149 women with PPROM were included in this study. Amniotic fluid samples were obtained by transabdominal amniocentesis. Amniotic fluid PTX3, SAP, and CRP concentrations were assessed using enzyme-linked immunosorbent assay. PTX3 and CRP concentrations were higher in women with MIAC, IAI, and microbial-associated IAI than in women without these conditions. SAP concentrations were only higher in the presence of IAI and microbial-associated IAI. Amniotic fluid PTX3 concentrations of 11 ng/mL were found to be the best value for identifying the presence of microbial-associated IAI and IAI in women with PPROM. To conclude, amniotic fluid pentraxins are involved in intra-amniotic inflammatory responses in pregnancies complicated by PPROM.

Early- or mid-trimester amniocentesis biomarkers for predicting preterm delivery: a meta-analysis

OBJECTIVE

To determine the value of early- or mid-trimester amniotic fluid levels of interleukin-6 (IL-6), matrix metalloproteinase-8 (MMP-8), and glucose for predicting preterm delivery.

METHODS

Randomized controlled trials and two-arm prospective, retrospective, cohorts, and case-controlled studies in which patients received early- or mid-trimester amniocentesis for karyotyping, and biomarker testing of the amniotic fluid was performed and delivery data were available were included in the analysis.

RESULTS

Outcome measures were the associations of amniotic fluid IL-6, MMP-8, and glucose levels with preterm delivery. Differences in means with 95% confidence intervals (CIs) were calculated. Of 288 articles identified, 14 were included in the meta-analysis with a total of 675 patients who had preterm birth and 2518 patients who had term births. The preterm-delivery group had significantly higher amniotic fluid IL-6 and MMP-8 levels, and a significantly lower glucose level than the term delivery group (IL-6: difference in means = 0.32, 95% CI: 0.22-0.43, p < 0.001; MMP-8: difference in means = 4.47, 95% CI: 0.83-8.11), p = 0.016; glucose: difference in means = -5.22, 95% CI: -8.19 to -2.26, p = 0.001) Conclusion: Early- or mid-trimester amniotic fluid IL-6, MMP-8, and glucose levels are useful for predicting the risk of preterm delivery. KEY MESSAGES Median amniotic fluid ferritin and IL-6 levels, and mean amniotic fluid ALP levels were higher in the preterm group. The preterm-delivery group had significantly higher amniotic fluid IL-6 and MMP-8 levels, and a significantly lower glucose level than the term-delivery group.

Proteomic Analysis of Early Mid-Trimester Amniotic Fluid Does Not Predict Spontaneous Preterm Delivery

Objective

The aim of this study was to identify early proteomic biomarkers of spontaneous preterm delivery (PTD) in mid-trimester amniotic fluid from asymptomatic women.

Methods

This is a case-cohort study. Amniotic fluid from mid-trimester genetic amniocentesis (14–19 weeks of gestation) was collected from 2008 to 2011. The analysis was conducted in 24 healthy women with subsequent spontaneous PTD (cases) and 40 randomly selected healthy women delivering at term (controls). An exploratory phase with proteomics analysis of pooled samples was followed by a verification phase with ELISA of individual case and control samples.

Results

The median (interquartile range (IQR: 25^th; 75^th percentiles) gestational age at delivery was 35+5 (33+6–36+6) weeks in women with spontaneous PTD and 40+0 (39+1–40+5) weeks in women who delivered at term. In the exploratory phase, the most pronounced differences were found in C-reactive protein (CRP) levels, that were approximately two-fold higher in the pooled case samples than in the pooled control samples. However, we could not verify these differences with ELISA. The median (25^th; 75^th IQR) CRP level was 95.2 ng/mL (64.3; 163.5) in women with spontaneous PTD and 86.0 ng/mL (51.2; 145.8) in women delivering at term (p = 0.37; t-test).

Conclusions

Proteomic analysis with mass spectrometry of mid-trimester amniotic fluid suggests CRP as a potential marker of spontaneous preterm delivery, but this prognostic potential was not verified with ELISA.

Mid-trimester maternal serum and amniotic fluid biomarkers for the prediction of preterm delivery and intrauterine growth retardation

AIM

Our purpose was to evaluate the predictive value of maternal serum and amniotic fluid biomarkers that were obtained at the time of genetic amniocentesis for preterm delivery and intrauterine growth retardation (IUGR).

METHODS

A prospective cohort analysis was conducted in 107 singleton pregnancies that underwent amniocentesis at 16-22 weeks according to standard genetic indications. Maternal blood and amniotic fluid obtained from genetic amniocentesis were tested for glucose, alkaline phosphatase (ALP), lactate dehydrogenase (LDH), ceruloplasmin, ferritin, high-sensitivity C-reactive protein and interleukin-6 (IL-6). Ninety-four pregnancies were followed until delivery.

RESULTS

Of the 94 patients, 16 (18.1%) delivered before 37 weeks and seven (7.5%) delivered a baby below the 10th percentile for gestational age. Amniotic fluid glucose levels were significantly lower in patients with preterm delivery than term deliveries (P = 0.01). Median amniotic fluid ferritin and IL-6 levels and mean amniotic fluid ALP levels were higher in the preterm group but this difference did not reach statistical significance. Mean maternal ALP and LDH levels tended to be insignificantly higher. Only median maternal blood ferritin levels in the IUGR group were found to be higher than patients who were appropriate for gestational age (P = 0.03).

CONCLUSION

Low amniotic fluid glucose levels are associated with risk of preterm delivery, whereas high maternal blood ferritin levels increase the risk for IUGR. Although this result is significant and notable, there is not enough clinical evidence to recommend their use as a screening test for preterm delivery and IUGR in routine practice.

Novel biomarkers for the prediction of the spontaneous preterm birth phenotype: a systematic review and meta-analysis

BACKGROUND

Being able to predict preterm birth is important, as it may allow a high-risk population to be selected for future interventional studies and help in understanding the pathways that lead to preterm birth.

OBJECTIVE

To investigate the accuracy of novel biomarkers to predict spontaneous preterm birth in women with singleton pregnancies and no symptoms of preterm labour.

SEARCH STRATEGY

Electronic searches in PubMed, Embase, Cinahl, Lilacs, and Medion, references of retrieved articles, and conference proceedings. No language restrictions were applied.

SELECTION CRITERIA

Observational studies that evaluated the accuracy of biomarkers proposed in the last decade to predict spontaneous preterm birth in asymptomatic women. We excluded studies in which biomarkers were evaluated in women with preterm labour.

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted data on study characteristics, quality, and accuracy. Data were arranged in 2 × 2 contingency tables and synthesised separately for spontaneous preterm birth before 32, 34, and 37 weeks of gestation. We used bivariate meta-analysis to estimate pooled sensitivities and specificities, and calculated likelihood ratios (LRs).

MAIN RESULTS

A total of 72 studies, including 89,786 women and evaluating 30 novel biomarkers, met the inclusion criteria. Only three biomarkers (proteome profile and prolactin in cervicovaginal fluid, and matrix metalloproteinase-8 in amniotic fluid) had positive LRs > 10. However, each of these biomarkers was evaluated in only one small study. Four biomarkers had a moderate predictive accuracy (interleukin-6 and angiogenin, in amniotic fluid; human chorionic gonadotrophin and phosphorylated insulin-like growth factor binding protein-1, in cervicovaginal fluid). The remaining biomarkers had low predictive accuracies.

CONCLUSIONS

None of the biomarkers evaluated in this review meet the criteria to be considered a clinically useful test to predict spontaneous preterm birth. Further large, prospective cohort studies are needed to evaluate promising biomarkers such as a proteome profile in cervicovaginal fluid.

Inflammatory cytokines and spontaneous preterm birth in asymptomatic women: a systematic review

OBJECTIVE

To estimate the association between inflammatory cytokines and the risk of spontaneous preterm birth in asymptomatic women.

DATA SOURCES

We searched electronic databases of the human literature in PubMed, EMBASE, and the Cochrane Library up to February 2010 using the following key words: "preterm/pre-term + (birth/delivery)" and "cytokine" or "inflammation/inflammatory + marker/biomarker."

METHODS OF STUDY SELECTION

We included observational studies that reported the association between common inflammatory cytokines and spontaneous preterm birth as an outcome in asymptomatic women. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using fixed and random effects models.

TABULATION, INTEGRATION, AND RESULTS

Seventeen primary studies comprising 6,270 participants met the inclusion criteria. Spontaneous preterm birth was strongly associated with increased levels of interleukin-6 (IL-6) in midtrimester cervicovaginal fluid (OR 3.05, 95% CI 2.00-4.67) (number needed to treat=7 for identifying an additional preterm delivery) and amniotic fluid (OR 4.52, 95% CI 2.67-7.65) (number needed to treat=7), but there was no association in plasma specimen (OR 1.5, 95% CI 0.7-3.0). Spontaneous preterm birth was strongly associated with increased C-reactive protein (CRP) levels in midtrimester amniotic fluid (OR 7.85, 95% CI 3.88-15.87) (number needed to treat=3), but the association was weak in plasma specimen (OR 1.53, 95% CI 1.22-1.90). There were insufficient data (fewer than three studies) for meta-analysis in other inflammatory cytokines.

CONCLUSION

Inflammatory cytokine IL-6 in cervicovaginal fluid and IL-6 and CRP in amniotic fluid but not in plasma are strongly associated with spontaneous preterm birth in asymptomatic women, suggesting that inflammation at the maternal-fetal interface, rather than systemic inflammation, may play a major role in the etiology of such spontaneous preterm births.