Interleukin-1 beta signals through the ERK signalling pathway to modulate human placental trophoblast migration and invasion in the first trimester of pregnancy

INTRODUCTION

Interleukin-1 beta (IL-1β) can promote cell migration, invasion and metastasis in various cancer cells. The mechanism of its role in human trophoblast has not been fully investigated. Therefore, we aimed to investigate the expression level of IL-1β in first trimester decidua and placenta and its potential role in regulation of extravillous trophoblast cell (EVT) invasion and migration.

METHODS

First trimester placenta and decidua were collected to study the expression levels of IL-1β and its receptors by immunohistochemical staining. Primary isolates of first trimester EVT or the HTR-8/SVneo trophoblast like cell line were used to assess migration and invasion. Matrix metalloproteinase levels were assessed by gelatin zymography and ELISA. The phosphorylation profile of signaling pathway proteins was detected with the Proteome Profiler Human Phospho-Kinase Array Kit. Differentially expressed proteins in cells was detected and verified by Western Blot.

RESULTS

IL-1β, its receptors and antagonist are expressed in first trimester placenta and decidua, exogenous IL-1β stimulates trophoblast cell outgrowth, migration and invasion through the ERK signaling pathway. IL-1β was significantly increased in the placenta at 6-7 weeks gestation compared with 8-9 weeks gestation (P < 0.0001). Transwell and RTCA assays indicated that IL-1β stimulates the invasion and migration of EVT. In addition, IL-1β promoted the phosphorylation of ERK 1/2. It also promoted the expression of MMP2 and MMP9 in EVT as demonstrated by gelatin zymography assay and enzyme linked immunosorbent assay.

DISCUSSION

This study demonstrated IL-1β expression in placenta and decidua, and that it regulates EVT invasion and migration.

PGE2 vs PGF2α in human parturition

Prostaglandin E2 (PGE2) and F2α (PGF2α) are the two most prominent prostanoids in parturition. They are involved in cervical ripening, membrane rupture, myometrial contraction and inflammation in gestational tissues. Because multiple receptor subtypes for PGE2 and PGF2α exist, coupled with diverse signaling pathways, the effects of PGE2 and PGF2α depend largely on the spatial and temporal expression of these receptors in intrauterine tissues. It appears that PGE2 and PGF2α play different roles in parturition. PGE2 is probably more important for labor onset, while PGF2α may play a more important role in labor accomplishment, which may be attributed to the differential effects of PGE2 and PGF2α in gestational tissues. PGE2 is more powerful than PGF2α in the induction of cervical ripening. In terms of myometrial contraction, PGE2 produces a biphasic effect with an initial contraction and a following relaxation, while PGF2α consistently stimulates myometrial contraction. In the fetal membranes, both PGE2 and PGF2α appear to be involved in the process of membrane rupture. In addition, PGE2 and PGF2α may also participate in the inflammatory process of intrauterine tissues at parturition by stimulating not only neutrophil influx and cytokine production but also cyclooxygenase-2 expression thereby intensifying their own production. This review summarizes the differential roles of PGE2 and PGF2α in parturition with respect to their production and expression of receptor subtypes in gestational tissues. Dissecting the specific mechanisms underlying the effects of PGE2 and PGF2α in parturition may assist in developing specific therapeutic targets for preterm and post-term birth.

Gestational tissue inflammatory biomarkers at term labor: A systematic review of literature

Parturition at term is characterized by inflammatory overload in both feto-maternal tissues. Despite the large number of individual studies on changes in inflammatory biomarkers linked to labor, a comprehensive profile of them in each of the uterine compartments is not available to better understand their mechanistic contributions to labor. This systematic review investigated the pro- and anti-inflammatory biomarkers reported in intra-uterine tissues (amnion, chorion, decidua, placenta, and myometrium) at term labor. We conducted a systematic review of studies on pro- and anti-inflammatory biomarkers (mRNA and/or protein) reported in feto-maternal tissues during normal human term labor, published in English (1980-2016), in 3 electronic data bases. From a total of 3712 citations, 172 were included for final review. Each tissue expresses a unique set of biomarkers at the time of term labor, but there is significant overlap between tissues. All tissues had IL-6, IL-8, IL-1β, COX-2, PGE-2, TNF-α, and hCAP18 in common at term labor. Common and unique inflammatory biomarkers are expressed in various feto-maternal compartments at term labor. Increase in pro-inflammatory markers in all gestational tissue signifies their harmonious functional role in promoting labor. Anti-inflammatory markers at term labor are hardly reported.

The Regulation of Interleukin-6 Secretion by Prostanoids and Members of the Tumor Necrosis Factor Superfamily in Fresh Villous Fragments of Term Human Placenta

OBJECTIVE

To determine whether prostanoids, nonsteroidal anti-inflammatory drugs (NSAIDs), and members of the tumor necrosis factor superfamily can regulate placental secretion of interleukin-6 (IL-6) and whether labor influences any such effects.

METHODS

Villous fragments of term, human placenta were kept in culture for up to 4 hours, and IL-6 concentrations were measured in the supernatant. We assessed the effects of the following prostanoids: PGE(2), PGF(2alpha), thromboxane A(2) mimetic (U-46619), and carbacyclin, a stable prostacyclin analogue (all at 1 microM); NSAIDs: indomethacin (150 microM) or nimesulide (100 microM); and Fas ligand (5 ng/mL).

RESULTS

Secretion (mean +/- standard error) of IL-6 was, for control conditions, 1.92 +/- 0.28 fmol/mg wet weight per 3 hours; for PGE(2), 3.57 +/- 0.29 fmol/mg wet weight per 3 hours, P <.01; and for carbacyclin, 3.11 +/- 0.44 fmol/mg wet weight per 3 hours, P <.01. Incubation with PGF(2alpha) or the thromboxane A(2) analogue, U46619, had no effect on IL-6 secretion under these conditions. Fas ligand stimulated IL-6 secretion (3.06 +/- 0.38 fmol/mg wet weight per 3 hours, P <.05). Labor did not alter the effects of prostanoids or FasL. The effects of NSAIDs were assessed over 4 hours. Secretion (median, interquartile range) was, under control conditions 3.26, 2.83-6.23 fmol/mg wet weight per 4 hours, with indomethacin 1.4, 1.28-3.21 (P <.05), and with nimesulide 0.75, 0.50-1.56 fmol/mg wet weight per 4 hours. The magnitude of the effect of Fas ligand in the presence of NSAIDs depended on whether the placentas were delivered before or after labor.

CONCLUSION

Prostanoids, NSAIDs, and the Fas ligand regulate placental IL-6 secretion. Although the effects of individual agents did not vary with the presence or absence of labor, modulation of IL-6 secretion by labor became apparent when agents were combined.

Discovery of HeLa Cell Contamination in HES Cells: Call for Cell Line Authentication in Reproductive Biology Research

Continuous cell lines are used frequently in reproductive biology research to study problems in early pregnancy events and parturition. It has been recognized for 50 years that many mammalian cell lines contain inter- or intraspecies contaminations with other cells. However, most investigators do not routinely test their culture systems for cross-contamination. The most frequent contributor to cross-contamination of cell lines is the HeLa cell isolated from an aggressive cervical adenocarcinoma. We report on the discovery of HeLa cell contamination of the human endometrial epithelial cell line HES isolated in our laboratory. Short tandem repeat analysis of 9 unique genetic loci demonstrated molecular identity between HES and HeLa cells. In addition, we verified that WISH cells, isolated originally from human amnion epithelium, were also contaminated with HeLa cells. Inasmuch as our laboratory did not culture HeLa cells at the time of HES cell derivations, the source of contamination was the WISH cell line. These data highlight the need for continued diligence in authenticating cell lines used in reproductive biology research.

Involvement of thromboxane A2 (TXA2) in the early stages of oleic acid-induced lung injury and the preventive effect of ozagrel, a TXA2 synthase inhibitor, in guinea-pigs

An intravenous injection of oleic acid into animals can produce a lung injury with hypoxaemia and pulmonary vascular hyper-permeability. Although oleic acid lung injury is used as a model of acute respiratory distress syndrome (ARDS), the precise mechanisms of the lung injury are still unclear. We have investigated whether thromboxane A2 (TXA2) participated in the lung injury and have evaluated the efficacy of ozagrel, a TXA2 synthase inhibitor, on the lung injury in guinea-pigs. Oleic acid injection increased the plasma level of TXB2, a stable metabolite of TXA2, and the time-course of plasma TXB2 was similar to that of the decreased partial oxygen pressure of arterial blood (Pao2) induced with oleic acid. Ozagrel administered intravenously 30 min before oleic acid injection prevented the decrease in Pao2 and pulmonary vascular hyper-permeability. It also prevented increases in lactate dehydrogenase activity, a measure of lung cell injury, TXB2 and its weight ratio to 6-keto prostaglandin F1 α in bronchoalveolar lavage fluid. Although ozagrel administered simultaneously with oleic acid ameliorated the decrease in Pao2, post treatment showed little effect. We suggest that TXA2 participated in the oleic acid lung injury, as an “early phase” mediator, and rapidly-acting TXA2 synthase inhibitors were effective in the prevention of acute lung injury.

Expression of inflammatory markers in pig amnion after intraamniotic infection with nonpathogenic or enteropathogenic Escherichia coli

The pig amnion was in vivo intraamniotically infected with E. coli for 10 h at 80-85 d of gestation either with the nonpathogenic O86 strain or enteropathogenic O55 strain. TNF-alpha, IL-10, IL-1beta and IFN-gamma were determined in amniotic fluids by ELISA, the expression of cytokines and some other inflammatory markers was determined by immunohistochemistry. Intraamniotic infection induced high levels of TNF-alpha in amniotic fluids which correlated with bacterial virulence whereas IL-10 was induced only by O86. The IL-1beta level did not increase significantly and was expressed in all infected membranes. IFN-gamma was negligible or absent. TNF-alpha, IL-12p40, calprotectin, HSP65 and gp91phox were found by immunohistochemistry only in amnion membranes infected with the enteropathogenic strain 055.

Markedly elevated levels of inflammatory cytokines in maternal serum and peritoneal washing during arrested labor

BACKGROUND

The role of inflammatory cytokines in the pathophysiology of arrested labor is currently unknown. We measured levels of inflammatory cytokines in maternal serum and peritoneal washings in arrested first stage of labor to assess the possible involvement of these mediators in this obstetric disorder.

METHODS

This was a prospective, case-control study involving 15 women who underwent cesarean section for arrested cervical dilatation (group I), 15 controls who were operated during active labor for nonreassuring fetal heart-rate tracing (group II) and 15 controls who were operated electively (group III). Blood samples were drawn from all women shortly before the operation. The presence of peritoneal fluid was assessed and peritoneal washings were obtained during the operation. All samples were assayed for the inflammatory cytokines interleukin (IL)-1beta, IL-6, IL-8 and soluble IL-2 receptor (sIL-2R) by solid-phase enzyme-linked immunosorbent assay (ELISA).

RESULTS

All women from group I and one patient (6.7%) from group II had some degree of peritoneal fluid accumulation, while none from group III had any. Serum samples from group I contained significantly higher IL-1beta, IL-6, IL-8 and IL-2R levels than both control groups. Peritoneal washings from group I contained significantly higher IL-1beta, IL-6 and IL-8 but similar IL-2R levels.

CONCLUSIONS

Arrested first stage of labor is associated with peritoneal fluid accumulation and increased levels of inflammatory cytokines in both serum and peritoneal fluids. Inflammatory cytokines may therefore be involved in the pathophysiology of arrested labor.

The distribution of activin and activin receptors in gestational tissues across human pregnancy and during labour

The aim of this study was to investigate localization and content of activin beta A-subunit and activin receptors in gestational tissues throughout pregnancy and in association with term labour. Placenta and fetal membranes were collected from women undergoing first and second trimester terminations and from women before and after term labour. Activin beta A-subunit and activin receptors IA, IB, IIA and IIB were studied by immunohistochemistry. Term tissues were analysed for activin A and follistatin content by ELISA and the presence of receptor proteins was assessed by Western hybridization. Activin beta A-subunit was localized to the syncytiotrophoblast and cytotrophoblast in placentae from all gestational ages, and to the amniotic epithelial and chorionic trophoblast layer at term. In placentae of first and second trimester, receptor proteins were localized to the syncytium, whereas at term, the distribution was confined predominantly to vascular endothelial cells of villous blood vessels. Receptor proteins in amnion were localized to some epithelial cells, mesenchyme and chorionic trophoblast. These findings suggest that activin A is secreted by and targets the placental syncytium and amniotic epithelium in early pregnancy, but at term targets the vascular endothelium of placenta and the fetal membranes. There were no differences with labour onset.