Chorioamniontis in preterm delivery is associated with degradation of decorin and biglycan and depletion of hyaluronan in fetal membranes

Palmitate and group B Streptococcus synergistically and differentially induce IL-1β from human gestational membranes

Introduction

Rupture of the gestational membranes often precedes major pregnancy complications, including preterm labor and preterm birth. One major cause of inflammation in the gestational membranes, chorioamnionitis (CAM) is often a result of bacterial infection. The commensal bacterium Streptococcus agalactiae, or Group B Streptococcus (GBS) is a leading infectious cause of CAM. Obesity is on the rise worldwide and roughly 1 in 4 pregnancy complications is related to obesity, and individuals with obesity are also more likely to be colonized by GBS. The gestational membranes are comprised of several distinct cell layers which are, from outermost to innermost: maternally-derived decidual stromal cells (DSCs), fetal cytotrophoblasts (CTBs), fetal mesenchymal cells, and fetal amnion epithelial cells (AECs). In addition, the gestational membranes have several immune cell populations; macrophages are the most common phagocyte. Here we characterize the effects of palmitate, the most common long-chain saturated fatty acid, on the inflammatory response of each layer of the gestational membranes when infected with GBS, using human cell lines and primary human tissue.

Results

Palmitate itself slightly but significantly augments GBS proliferation. Palmitate and GBS co-stimulation synergized to induce many inflammatory proteins and cytokines, particularly IL-1β and matrix metalloproteinase 9 from DSCs, CTBs, and macrophages, but not from AECs. Many of these findings are recapitulated when treating cells with palmitate and a TLR2 or TLR4 agonist, suggesting broad applicability of palmitate-pathogen synergy. Co-culture of macrophages with DSCs or CTBs, upon co-stimulation with GBS and palmitate, resulted in increased inflammatory responses, contrary to previous work in the absence of palmitate. In whole gestational membrane biopsies, the amnion layer appeared to dampen immune responses from the DSC and CTB layers (the choriodecidua) to GBS and palmitate co-stimulation. Addition of the monounsaturated fatty acid oleate, the most abundant monounsaturated fatty acid in circulation, dampened the proinflammatory effect of palmitate.

Discussion

These studies reveal a complex interplay between the immunological response of the distinct layers of the gestational membrane to GBS infection and that such responses can be altered by exposure to long-chain saturated fatty acids. These data provide insight into how metabolic syndromes such as obesity might contribute to an increased risk for GBS disease during pregnancy.

Prediction of Preterm Delivery Using Serum Ischemia Modified Albumin, Biglycan, and Decorin Levels in Women with Threatened Preterm Labor

OBJECTIVE

 The serum ischemia modified albumin (IMA), biglycan, and decorin levels of pregnant women who were hospitalized for threatened preterm labor were measured.

METHODS

 Fifty-one consecutive pregnant women with a single pregnancy between the 24th and 36th weeks with a diagnosis of threatened preterm labor were included in the present prospective cohort study.

RESULTS

 As a result of multivariate logistic regression analysis for predicting preterm delivery within 24 hours, 48 hours, 7 days, 14 days, ≤ 35 gestational weeks, and ≤ 37 gestational weeks after admission, area under the curve (AUC) (95% confidence interval [CI[) values were 0.95 (0.89-1.00), 0.93 (0.86-0.99), 0.91 (0.83-0.98), 0.92 (0.85-0.99), 0.82 (0.69-0.96), and 0.89 (0.80-0.98), respectively. In the present study, IMA and biglycan levels were found to be higher and decorin levels lower in women admitted to the hospital with threatened preterm labor and who gave preterm birth within 48 hours compared with those who gave birth after 48 hours.

CONCLUSION

 In pregnant women admitted to the hospital with threatened preterm labor, the prediction preterm delivery of the combined model created by adding IMA, decorin, and biglycan in addition to the TVS CL measurement was higher than the TVS CL measurement alone.

CLINICAL TRIAL REGISTRATION

 The present trial was registered at ClinicalTrials.gov, number NCT04451928.

Leveraging bioengineering to assess cellular functions and communication within human fetal membranes

The fetal membranes enclose the growing fetus and amniotic fluid. Preterm prelabor rupture of fetal membranes is a leading cause of preterm birth. Fetal membranes are composed of many different cell types, both structural and immune. These cells must coordinate functions for tensile strength and membrane integrity to contain the growing fetus and amniotic fluid. They must also balance immune responses to pathogens with maintaining maternal-fetal tolerance. Perturbation of this equilibrium can lead to preterm premature rupture of membranes without labor. In this review, we describe the formation of the fetal membranes to orient the reader, discuss some of the common forms of communication between the cell types of the fetal membranes, and delve into the methods used to tease apart this paracrine signaling within the membranes, including emerging technologies such as organ-on-chip models of membrane immunobiology.

Roles of Two Small Leucine-Rich Proteoglycans Decorin and Biglycan in Pregnancy and Pregnancy-Associated Diseases

Two small leucine-rich proteoglycans (SLRP), decorin and biglycan, play important roles in structural–functional integrity of the placenta and fetal membranes, and their alterations can result in several pregnancy-associated diseases. In this review, we briefly discuss normal placental structure and functions, define and classify SLRPs, and then focus on two SLRPs, decorin (DCN) and biglycan (BGN). We discuss the consequences of deletions/mutations of DCN and BGN. We then summarize DCN and BGN expression in the pregnant uterus, myometrium, decidua, placenta, and fetal membranes. Actions of these SLRPs as ligands are then discussed in the context of multiple binding partners in the extracellular matrix and cell surface (receptors), as well as their alterations in pathological pregnancies, such as preeclampsia, fetal growth restriction, and preterm premature rupture of membranes. Lastly, we raise some unanswered questions as food for thought.

Serum Decorin and Biglycan as Potential Biomarkers to Predict PPROM in Early Gestation

Preterm birth is a leading cause of neonatal mortality in the US and globally, with preterm premature rupture of fetal membranes (PPROM) accounting for one third of preterm births. Currently no predictive diagnostics are available to precisely assess risk and potentially reduce the incidence of PPROM. Bigycan and decorin, the main proteoglycans present in human fetal membranes, are involved in the physiological maturation of fetal membranes as well as in the pathophysiology of preterm birth. The serum protein sex hormone-binding globulin (SHBG) has recently been identified as a predictor of spontaneous preterm birth. We hypothesize that the balance between serum decorin and biglycan on one hand and SHBG on the other hand may provide insight into the status of the fetal membranes in early pregnancy, thereby predicting PPROM prior to symptoms. Using chart review, 18 patients with confirmed cases of PPROM were identified from 2013-2016. Second trimester residual serum was retreived from freezer storage for these cases along with 5 matched controls for each case. The biomarkers biglycan, decorin and SHBG were analyzed first separately, then in combination to determine their ability to predict PPROM. The predictive score for the combined model displays an AUC = 0.774. The ROC curve of the predicted score has an optimal threshold of 0.238 and a sensitivity and specificity of 0.72 and 0.84 respectively. This prenatal serum panel is a promising serum screening-based biochemical model to predict PPROM in asymptomatic women.

Transcriptomic profiling of fetal membranes of mice deficient in biglycan and decorin as a model of preterm birth†

Approximately, 25% of all preterm births are due to preterm premature rupture of membranes. Mice deficient in proteoglycans biglycan (Bgn) and decorin (Dcn) display abnormal fetal membranes and increased incidence of preterm birth. We conducted RNA-Seq to profile fetal membranes and identify molecular pathways that may lead to preterm birth in double knockout (DKO) mice (Bgn-/-; Dcn-/-) compared to wild-type (WT) at two different gestational stages, E12 and E18 (n = 3 in each group). 3264 transcripts were differentially regulated in E18 DKO vs. WT fetal membranes, and 96 transcripts differentially regulated in E12 DKO vs. WT fetal membranes (FDR < 0.05, log 2 FC ≥ 1). Differentially regulated transcripts in E18 DKO fetal membranes were significantly enriched for genes involved in cell cycle regulation, extracellular matrix-receptor interaction, and the complement cascade. Fifty transcripts involved in the cell cycle were altered in E18 DKO fetal membranes (40↓, 10↑, FDR < 0.05), including p21 and p57 (↑), and Tgfb2, Smad3, CycA, Cdk1, and Cdk2(↓). Thirty-one transcripts involved in the complement cascade were altered (11↓, 20↑, FDR < 0.05) in E18 DKO fetal membranes, including C1q, C2, and C3 (↑). Differentially expressed genes in the top three molecular pathways (1) showed evidence of negative or purifying selection, and (2) were significantly enriched (Z-score > 10) for transcription factor binding sites for Nr2f1 at E18. We propose that in DKO mice, cell cycle arrest results in lack of cell proliferation in fetal membranes, inability to contain the growing fetus, and preterm birth.

Cytotrophoblasts suppress macrophage-mediated inflammation through a contact-dependent mechanism

PROBLEM

Gestational membrane (GM) infection provokes inflammation and can result in preterm prelabor rupture of membranes (PPROM). The choriodecidual layer of the GM includes decidual stromal cells (DSC), cytotrophoblasts (CTB), and macrophages (Mφ). Our laboratory has previously shown that DSCs suppress Mφ TNF-α production through secreted prostaglandin E₂ . We hypothesized that CTBs would also inhibit Mφ cytokine expression through secreted mediators.

METHOD OF STUDY

THP.1 Mφ-like cells with an NF-κB reporter construct or human blood monocyte-derived Mφ were co-cultured with the Jeg3 CTB cell line or primary human CTBs and challenged with group B streptococcus (GBS) or Toll-like receptor (TLR) agonists. Conditioned medium generated from CTB cultures was applied to Mφ cultures before infection or treatment. Alternatively, CTBs were co-incubated with, but physically separated from, Mφ and GBS or TLR-stimulated. NF-κB was assessed via alkaline phosphatase assay, and proinflammatory mediators were assessed by qRT-PCR and ELISA.

RESULTS

CTBs suppressed GBS- or TLR-stimulated Mφ NF-κB activity, and TNF-α and MMP9 production. Direct physical contact between CTBs and Mφ was required for full immunosuppression. Immunosuppression could be overcome by increasing the ratio of Mφ to CTB.

CONCLUSIONS

CTBs limit Mφ NF-κB activation and production of TNF-α and MMP9 through an as-yet unknown, cell-to-cell contact-mediated mechanism. This suppression is distinct from the PGE₂ -mediated Mφ TNF-α suppression by DSC, suggesting that DSCs and CTBs regulate Mφ inflammation through distinct mechanisms. How Mφ integrates these signals in an intact GM will be paramount to determining causes and prevention of PPROM.

Serum Decorin and Biglycan as Potential Biomarkers to Predict PPROM in Early Gestation

Preterm birth is a leading cause of neonatal mortality in the US and globally, with preterm premature rupture of fetal membranes (PPROM) accounting for one third of preterm births. Currently no predictive diagnostics are available to precisely assess risk and potentially reduce the incidence of PPROM. Bigycan and decorin, the main proteoglycans present in human fetal membranes, are involved in the physiological maturation of fetal membranes as well as in the pathophysiology of preterm birth. The serum protein sex hormone-binding globulin (SHBG) has recently been identified as a predictor of spontaneous preterm birth. We hypothesize that the balance between serum decorin and biglycan on one hand and SHBG on the other hand may provide insight into the status of the fetal membranes in early pregnancy, thereby predicting PPROM prior to symptoms. Using chart review, 18 patients with confirmed cases of PPROM were identified from 2013-2016. Second trimester residual serum was retreived from freezer storage for these cases along with 5 matched controls for each case. The biomarkers biglycan, decorin and SHBG were analyzed first separately, then in combination to determine their ability to predict PPROM. The predictive score for the combined model displays an AUC = 0.774. The ROC curve of the predicted score has an optimal threshold of 0.238 and a sensitivity and specificity of 0.72 and 0.84 respectively. This prenatal serum panel is a promising serum screening-based biochemical model to predict PPROM in asymptomatic women.

Serum decorin measurement in prediction of the risk for preterm birth

OBJECTIVE

To define serum decorin (sDEC) levels in healthy pregnants and in patients with preterm labor (PTL), and to introduce possible role of sDEC in predicting the risk for preterm birth (PTB).

MATERIALS AND METHODS

Thirty-one women with diagnosis of PTL between 24th to 32nd weeks of pregnancy were compared with 44 healthy pregnants in this prospective case-control study. Maternal blood sDEC and uterine cervical length (CL) measurements were conducted at referral.

RESULTS

Median sDEC level was significantly decreased in PTL group (p = 0.013). Median CL was significantly shorter in PTL group (p < 0.001). There was not any correlation between sDEC level and maternal age, BMI, and gestational age at blood sampling time within PTL (p = 0.955, p = 0.609, p = 0.079, respectively) and control groups (p = 0.652, p = 0.131, and p = 0.921, respectively). There was not any association between sDEC level and PTB within 7 days, before 34th weeks, but before 37th weeks there was (p = 0.206, 0.091, and p = 0.026, respectively). There was not any correlation between sDEC level and the CL in PTL group (p = 0.056).

CONCLUSIONS

sDEC has a limited effect in prediction of PTB within a week or before 34th weeks. Combination of sDEC with CL measurements predicted PTB before 37th weeks.

CONCLUSION

Decidual stromal cell-derived PGE2 regulates macrophage responses to microbial threat

PROBLEM

Bacterial chorioamnionitis causes adverse pregnancy outcomes, yet host-microbial interactions are not well characterized within gestational membranes. The decidua, the outermost region of the membranes, is a potential point of entry for bacteria ascending from the vagina to cause chorioamnionitis. We sought to determine whether paracrine communication between decidual stromal cells and macrophages shaped immune responses to microbial sensing.

METHOD OF STUDY

Decidual cell-macrophage interactions were modeled in vitro utilizing decidualized, telomerase-immortalized human endometrial stromal cells (dTHESCs) and phorbol ester-differentiated THP-1 macrophage-like cells. The production of inflammatory mediators in response to LPS was monitored by ELISA for both cell types, while phagocytosis of bacterial pathogens (Escherichia coli and Group B Streptococcus (GBS)) was measured in THP-1 cells or primary human placental macrophages. Diclofenac, a non-selective cyclooxygenase inhibitor, and prostaglandin E₂ (PGE₂ ) were utilized to interrogate prostaglandins as decidual cell-derived paracrine immunomodulators. A mouse model of ascending chorioamnionitis caused by GBS was utilized to assess the colocalization of bacteria and macrophages in vivo and assess PGE₂ production.

RESULTS

In response to LPS, dTHESC and THP-1 coculture demonstrated enhancement of most inflammatory mediators, but a potent suppression of macrophage TNF-α generation was observed. This appeared to reflect a paracrine-mediated effect of decidual cell-derived PGE₂ . In mice with GBS chorioamnionitis, macrophages accumulated at sites of bacterial invasion with increased PGE₂ in amniotic fluid, suggesting such paracrine effects might hold relevance in vivo.

CONCLUSION

These data suggest key roles for decidual stromal cells in modulating tissue responses to microbial threat through release of PGE₂ .

Fetal membrane imaging and the prediction of preterm birth: a systematic review, current issues, and future directions

BACKGROUND

Preterm premature rupture of membranes (PPROM) is the largest identifiable cause of preterm birth. There is currently no good screening test for PPROM in low-risk asymptomatic patients. Our goal was to identify how imaging methods can be utilized for examining the risks for PPROM in asymptomatic patients.

METHODS

This paper is a systematic review of the literature on fetal membrane thickness and its use for the prediction of PPROM. Four key studies are identified and reviewed; two in vitro studies and two in vivo ultrasound studies each using differing methodologies. Additionally reviewed is a study using Optical Coherence Tomography, an emerging technique using near-infrared technology to produce high-resolution images.

RESULTS

There is currently insufficient data to determine the association between fetal membrane thickness and PPROM by ultrasound.

CONCLUSIONS

Fetal membrane thickness could have relevant clinical ramifications for the prediction of PPROM. Suggested improvements in study methodology and design will lead to progress in this area of research, as well as the use of newer technologies. Larger sample sizes, histological comparison, uniform methodologies for data collection, longitudinal study design and expanding data analysis beyond fetal membrane thickness to other properties would expand our knowledge in this field. In addition, transvaginal ultrasound should be utilized to improve resolution, as well as emerging methodologies such as MRI fusion imaging using ultrasound and Shear Wave Elastography.

Damage-Associated Molecular Pattern and Fetal Membrane Vascular Injury and Collagen Disorganization in Lipopolysaccharide-Induced Intra-amniotic Inflammation in Fetal Sheep

To understand the changes in the structural integrity of fetal membranes during intrauterine inflammation, we evaluated the time course of expression and localization of damage-associated molecular patterns (DAMPs) and injury/remodeling in collagen and vascular smooth muscle. Time-mated ewes received intra-amniotic (IA) saline or IA lipopolysaccharide (LPS) for 5 hours to 15 days prior to a preterm delivery at 125 ± 2 days (n = 5-7 animals/group). The DAMP high mobility group box 1 (HMGB1) protein assessed by Western blot was induced within 24 hours after IA LPS in the fetal membranes, and HMGB1 expression was localized to amnion epithelium, chorion vascular endothelium, and infiltrating inflammatory cells by immunohistology. Markers of vascular injury, intercellular adhesion molecule 1, and tissue plasminogen activator messenger RNA (mRNA) expression increased 5 to 12 hours after IA LPS in the chorioamnion indicating vascular injury. Chorion vascular remodeling with increased chorion arteriolar smooth muscle actin expression by morphometric analyses of immunohistology was noted 15 days after IA LPS. Collagen expression was nonhomogeneous by histochemical staining, and there was a trend toward decreased mRNA expression of collagen subunit COL5A1 after IA LPS.

CONCLUSIONS

Intrauterine inflammation induced early increases in HMGB1 in the chorioamnion with a concomitant vascular injury followed by chorion arteriolar hypertrophy. There was nonhomogeneous collagen expression in the chorioamnion. These results have implications for understanding the pathogenesis of IA inflammation-induced preterm rupture of membranes.