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Abstract Background Parturition is an inflammation process. Exaggerated inflammatory reactions in infection lead to preterm birth. Although nuclear factor kappa B (NF-κB) has been recognized as a classical transcription factor mediating inflammatory reactions, those mediated by NF-κB per se are relatively short-lived. Therefore, there may be other transcription factors involved to sustain NF-κB-initiated inflammatory reactions in gestational tissues in infection-induced preterm birth. Methods Cebpd-deficient mice were generated to investigate the role of CCAAT enhancer-binding protein δ (C/EBPδ) in lipopolysaccharide (LPS)-induced preterm birth, and the contribution of fetal and maternal C/EBPδ was further dissected by transferring Cebpd −/− or WT embryos to Cebpd −/− or WT dams. The effects of C/EBPδ pertinent to parturition were investigated in mouse and human myometrial and amnion cells. The interplay between C/EBPδ and NF-κB was examined in cultured human amnion fibroblasts. Results The mouse study showed that LPS-induced preterm birth was delayed by Cebpd deficiency in either the fetus or the dam, with further delay being observed in conceptions where both the dam and the fetus were deficient in Cebpd. Mouse and human studies showed that the abundance of C/EBPδ was significantly increased in the myometrium and fetal membranes in infection-induced preterm birth. Furthermore, C/EBPδ participated in LPS-induced upregulation of pro-inflammatory cytokines as well as genes pertinent to myometrial contractility and fetal membrane activation in the myometrium and amnion respectively. A mechanistic study in human amnion fibroblasts showed that C/EBPδ, upon induction by NF-κB, could serve as a supplementary transcription factor to NF-κB to sustain the expression of genes pertinent to parturition. Conclusions C/EBPδ is a transcription factor to sustain the expression of gene initiated by NF-κB in the myometrium and fetal membranes in infection-induced preterm birth. Targeting C/EBPδ may be of therapeutic value in the treatment of infection-induced preterm birth.

IntroductionFetal membrane inflammation is an integral event of parturition. However, excessive pro-inflammatory cytokines can impose threats to the fetus. Coincidentally, the fetal membranes express abundant 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1), which generates biologically active cortisol to promote labor through induction of prostaglandin synthesis. Given the well-recognized anti-inflammatory actions of glucocorticoids, we hypothesized that cortisol regenerated in the fetal membranes might be engaged in restraining fetus-hazardous pro-inflammatory cytokine production for the safety of the fetus, while reserving pro-labor effect on prostaglandin synthesis to ensure safe delivery of the fetus.MethodsThe hypothesis was examined in human amnion tissue and cultured primary human amnion fibroblasts as well as a mouse model.Results11β-HSD1 was significantly increased in the human amnion in infection-induced preterm birth. Studies in human amnion fibroblasts showed that lipopolysaccharide (LPS) induced 11β-HSD1 expression synergistically with cortisol. Cortisol completely blocked NF-κB-mediated pro-inflammatory cytokine expression by LPS, but STAT3-mediated cyclooxygenase 2 expression, a crucial prostaglandin synthetic enzyme, remained. Further studies in pregnant mice showed that corticosterone did not delay LPS-induced preterm birth, but alleviated LPS-induced fetal organ damages, along with increased 11β-HSD1, cyclooxygenase 2, and decreased pro-inflammatory cytokine in the fetal membranes.DiscussionThere is a feed-forward cortisol regeneration in the fetal membranes in infection, and cortisol regenerated restrains pro-inflammatory cytokine expression, while reserves pro-labor effect on prostaglandin synthesis. This dual role of cortisol regeneration can prevent excessive pro-inflammatory cytokine production, while ensure in-time delivery for the safety of the fetus.

Abstract Hyalectan cleavage may play an important role in extracellular matrix remodeling. However, the proteolytic enzyme responsible for hyalectan degradation for fetal membrane rupture at parturition remains unknown. Here, we reveal that versican (VCAN) is the major hyalectan in the amnion, where its cleavage increases at parturition with spontaneous rupture of membrane. We further reveal that ADAMTS4 is a crucial proteolytic enzyme for VCAN cleavage in the amnion. Inflammatory factors may enhance VCAN cleavage by inducing ADAMTS4 expression and inhibiting ADAMTS4 endocytosis in amnion fibroblasts. In turn, versikine, the VCAN cleavage product, induces inflammatory factors in amnion fibroblasts, thereby forming a feedforward loop between inflammation and VCAN degradation. Mouse studies show that intra-amniotic injection of ADAMTS4 induces preterm birth along with increased VCAN degradation and proinflammatory factors abundance in the fetal membranes. Conclusively, there is enhanced VCAN cleavage by ADAMTS4 in the amnion at parturition, which can be reenforced by inflammation.

Abstract Background Inflammation of the fetal membranes is an indispensable event of labor onset at both term and preterm birth. Interleukin-33 (IL-33) is known to participate in inflammation via ST2 (suppression of tumorigenicity 2) receptor as an inflammatory cytokine. However, it remains unknown whether IL-33/ST2 axis exists in human fetal membranes to promote inflammatory reactions in parturition. Methods The presence of IL-33 and ST2 and their changes at parturition were examined with transcriptomic sequencing, quantitative real-time polymerase chain reaction, Western blotting or immunohistochemistry in human amnion obtained from term and preterm birth with or without labor. Cultured primary human amnion fibroblasts were utilized to investigate the regulation and the role of IL-33/ST2 axis in the inflammation reactions. A mouse model was used to further study the role of IL-33 in parturition. Results Although IL-33 and ST2 expression were detected in both epithelial and fibroblast cells of human amnion, they are more abundant in amnion fibroblasts. Their abundance increased significantly in the amnion at both term and preterm birth with labor. Lipopolysaccharide, serum amyloid A1 and IL-1β, the inflammatory mediators pertinent to labor onset, could all induce IL-33 expression through NF-κB activation in human amnion fibroblasts. In turn, via ST2 receptor, IL-33 induced the production of IL-1β, IL-6 and PGE2 in human amnion fibroblasts via the MAPKs-NF-κB pathway. Moreover, IL-33 administration induced preterm birth in mice. Conclusion IL-33/ST2 axis is present in human amnion fibroblasts, which is activated in both term and preterm labor. Activation of this axis leads to increased production of inflammatory factors pertinent to parturition, and results in preterm birth. Targeting the IL-33/ST2 axis may have potential value in the treatment of preterm birth.

Abstract Background The human amnion is an intrauterine tissue which is involved in the initiation of parturition. In-depth understanding of gene expression signatures of individual cell types in the amnion with respect to membrane rupture at parturition may help identify crucial initiators of parturition for the development of specific strategies to prevent preterm birth, a leading cause of perinatal mortality. Results Six major cell types were revealed in human amnion including epithelial cells, fibroblasts and immunocytes as well as three other cell types expressing dual cell markers including epithelial/fibroblast, immune/epithelial and immune/fibroblast markers. The existence of cell types expressing these dual cell markers indicates the presence of epithelial-mesenchymal (EMT), epithelial-immune (EIT) and mesenchymal-immune (MIT) transitions in amnion at parturition. We found that the rupture zone of amnion exhibited some specific increases in subcluster proportions of immune and EMT cells related to extracellular matrix remodeling and inflammation in labor. The non-rupture zone exhibited some common changes in subcluster compositions of epithelial and fibroblast cells with the rupture zone in labor, particularly those related to oxidative stress and apoptosis in epithelial cells and zinc ion transport in fibroblasts. Moreover, we identified that C–C motif chemokine ligand 20 (CCL20) was among the top up-regulated genes in amnion epithelial cells, fibroblasts and immunocytes in the rupture zone at parturition. Studies in pregnant mice showed that administration of CCL20 induced immunocytes infiltration to tissues at the maternal–fetal interface and led to preterm birth. Conclusions Apart from the conventional epithelial, fibroblast and immunocytes, human amnion cells may undergo EMT, EIT and FIT in preparation for parturition. Intense inflammation and ECM remodeling are present in the rupture zone, while enhanced apoptosis and oxidative stress in epithelial cells and zinc ion transport in fibroblasts are present in amnion regardless of the rupture zones at parturition. CCL20 derived from the major cell types of the amnion participates in labor onset.

Inflammation of the fetal membranes is an indispensable event of parturition, with increasing prostaglandin E2 (PGE2) synthesis as one of the ultimate products that prime labor onset. In addition to PGE2, the fetal membranes also boast a large capacity for cortisol regeneration. It is intriguing how increased PGE2 synthesis is achieved in the presence of increasing amounts of classical anti-inflammatory glucocorticoids in the fetal membranes at parturition. 15(S)-hydroxyeicosatetraenoic acid (15(S)-HETE) synthesized by lipoxygenase 15/15B (ALOX15/15B) has been shown to enhance inflammation-induced PGE2 synthesis in amnion fibroblasts. Here, we examined whether glucocorticoids could induce ALOX15/15B expression and 15(S)-HETE production to promote PGE2 synthesis in amnion fibroblasts at parturition. We found that cortisol and 15(S)-HETE abundance increased parallelly in the amnion at parturition. Cortisol induced ALOX15/15B expression and 15(S)-HETE production paradoxically in amnion fibroblasts. Mechanism study revealed that this paradoxical induction was mediated by p300-mediated histone acetylation and interaction of glucocorticoid receptor with transcription factors CREB and STAT3. Conclusively, cortisol regenerated in the fetal membranes can paradoxically induce ALOX15/15B expression and 15(S)-HETE production in human amnion fibroblasts, which may further assist in the induction of PGE2 synthesis in the inflammatory responses of the fetal membranes for parturition.

BackgroundBradykinin (BK) and its biologically active metabolite des-Arg9 bradykinin (DABK) play a pivotal role in inflammation. Since chorioamnionitis is the leading cause of preterm birth and prostaglandin E2 (PGE2) derived from the amnion is key to labor initiation, we investigated if bradykinin peptides are part of the regulatory network of PGE2 synthesis in human amnion at parturition.MethodsHuman amnion tissue was obtained from term and preterm birth for the study of the changes of the bradykinin system at parturition. Cultured primary human amnion fibroblasts, the major source of PGE2, were used to study the effects of bradykinin peptides on PTGS2 expression and PGE2 production as well as the effects of infection mediators on bradykinin receptors.ResultsBradykinin peptides and their receptors BDKRB1 and BDKRB2 were present in human amnion, and their abundance increased in term and preterm labor. However, transcripts of the genes encoding the bradykinin precursor and its proteolytic cleavage enzymes were hardly detectable in human amnion despite the increased abundance of bradykinin peptides in term and preterm labor, suggesting that there is an alternative source of bradykinin peptides for human amnion and their actions are enhanced in human amnion at parturition. In-vitro studies in cultured human amnion fibroblasts showed that both BK and DABK increased the expression of prostaglandin-endoperoxide synthase 2 (PTGS2), the rate-limiting enzyme in prostaglandin synthesis, and subsequent PGE2 production. These effects of BK and DABK were mediated through BDKRB2 and BDKRB1 receptors, respectively, with subsequent activation of the p38 and ERK1/2 pathways. Moreover, lipopolysaccharide (LPS) and serum amyloid A1 (SAA1), the important mediators of infectious inflammation, induced the expression of both BDKRB1 and BDKRB2 through toll-like receptor 4 (TLR4). Induction of BDKRB1 and BDKRB2 expression by LPS and SAA1 enhanced BK- or DABK-induced PTGS2 expression and PGE2 production in human amnion fibroblasts.ConclusionsThis study demonstrated for the first time that the human amnion is a target tissue of bradykinin peptides and the bradykinin system may be part of the regulatory network of PTGS2 expression and PGE2 production in human amnion fibroblasts at both term and preterm birth, which may be enhanced by infection.

Aims: Foramen ovale (FO) valve with a shape or motion abnormality is frequently detected during routine obstetric ultrasonic examinations. However, the hemodynamics mechanism of this entity remains unclear. The purpose of the study is to determine the relevance of interatrial communication restriction and resultant morphological modifications.Materials and Methods: We reviewed the echocardiographic records of fetuses with isolated abnormal FO valve evaluated between January of 2010 and december of 2016. The size (DFO) of the FO orifice, opening angle (α) of the FO valve, and dimensions of cardiac chambers, FO channel outlet (DOUT) and inferior vena cava (DIVC) were measured. We evaluated their (DFO, DOUT, α) relationships to the diameters of RA and DIVC. Five hundred and seventy normal fetuses were selected to establish the normal range of the DOUT/DIVC ratio so as to provide a criterion for restriction.Results: An abnormal FO valve was identified in 89 fetuses without congenital heart disease, with restriction noted in 62 fetuses (45 fetuses with RA dilatation, 12 fetuses with RA and RV dilatation, and 5 fetuses with no RA dilatation). There were no significant correlations between RA/LA and DFO/DIVC, RA/ LA and α. RA/LA was negatively correlated with DOUT/DIVC (R2=0.97, p<0.01).Conclusions: For a fetus with an abnormal FO valve, right heart dilatation could be considered as an indicator of interatrial communication restriction, which could be assessed by evaluating the FO channel outlet. The degree of right atrium dilatation indicates the severity of the restriction. [ABSTRACT FROM AUTHOR]