Synergistic effects of tumor necrosis factor-α and insulin-like growth factor-I on survival of human trophoblast-derived BeWo cell line

A systematic review and risk of bias analysis of in vitro studies on trophoblast response to immunological triggers

An increasing amount of evidence suggests that immune responses may affect trophoblast functioning, which in turn may play a role in gestational disorders and fetal development. This systematic review offers the first summary of in vitro studies on the trophoblast response to immunological triggers, in conjunction with a risk of bias analysis. A search in Pubmed and Embase yielded 110 relevant studies. Primary trophoblasts were the most commonly used cell type, but trophoblast subtypes were not always defined. Similarly, the exact natures of trophoblast cell lines were sometimes unclear. Cytokines and Toll-like receptor agonists were often used as interventions, but most studies focused on a select few substances such as tumor necrosis factor-α and lipopolysaccharide. In regard to the outcome parameters, some important trophoblast functions, such as hormone production and barrier formation were underrepresented. Whether or not risk of bias was high varied strongly between types of bias. Risk of selection bias, for example, was usually low. However, none of the included studies mentioned blinding or plate randomization. Only a select few studies mentioned passage numbers, use of vehicle control or conflict of interest. In conclusion, better characterization of trophoblast subtypes and a broader range of studied interventions and outcome parameters would contribute to a more complete understanding of trophoblast responses to immune stimuli. Additionally, researchers are encouraged to replicate experiments and pay close attention when setting up and writing down methodologies, in order to improve the reproducibility and translatability of their work.

Obesity and gestational diabetes independently and collectively induce specific effects on placental structure, inflammation and endocrine function in a cohort of South African women

Maternal obesity and gestational diabetes mellitus (GDM) are associated with insulin resistance and health risks for mother and offspring. Obesity is also characterized by low-grade inflammation, which in turn, impacts insulin sensitivity. The placenta secretes inflammatory cytokines and hormones that influence maternal glucose and insulin handling. However, little is known about the effect of maternal obesity, GDM and their interaction, on placental morphology, hormones and inflammatory cytokines. In a South African cohort of non-obese and obese pregnant women with and without GDM, this study examined placental morphology using stereology, placental hormone and cytokine expression using real-time PCR, western blotting and immunohistochemistry, and circulating TNFα and IL-6 concentrations using ELISA. Placental expression of endocrine and growth factor genes was not altered by obesity or GDM. However, LEPTIN gene expression was diminished, syncytiotrophoblast TNFα immunostaining elevated and stromal and fetal vessel IL-6 staining reduced in the placenta of obese women in a manner that was partly influenced by GDM status. Placental TNFα protein abundance and maternal circulating TNFα concentrations were reduced in GDM. Both maternal obesity and, to a lesser extent, GDM were accompanied by specific changes in placental morphometry. Maternal blood pressure and weight gain and infant ponderal index were also modified by obesity and/or GDM. Thus, obesity and GDM have specific impacts on placental morphology and endocrine and inflammatory states that may relate to pregnancy outcomes. These findings may contribute to developing placenta-targeted treatments that improve mother and offspring outcomes, which is particularly relevant given increasing rates of obesity and GDM worldwide. KEY POINTS: Rates of maternal obesity and gestational diabetes (GDM) are increasing worldwide, including in low-middle income countries (LMIC). Despite this, much of the work in the field is conducted in higher-income countries. In a well-characterised cohort of South African women, this study shows that obesity and GDM have specific impacts on placental structure, hormone production and inflammatory profile. Moreover, such placental changes were associated with pregnancy and neonatal outcomes in women who were obese and/or with GDM. The identification of specific changes in the placenta may help in the design of diagnostic and therapeutic approaches to improve pregnancy and neonatal outcomes with particular significant benefit in LMICs.

Inflammation-Related Molecules at the Maternal-Fetal Interface during Pregnancy and in Pathologically Altered Endometrium

The blastocyst expresses paternally derived alloantigens and induces inflammation during implantation. However, it is necessary for the onset of pregnancy. An abnormal response might result in a pathological course of pregnancy or pregnancy failure. On the other hand, a state of maternal immune tolerance is necessary to ensure the normal development of pregnancy by suppressing inflammatory processes. This article discusses recognized mechanisms and the significance of inflammatory processes for embryo implantation and pregnancy establishment. We would also like to present disorders involving excessive inflammatory response and their influence on events occurring during embryo implantation. The chain of correlation between the processes responsible for embryo implantation and the subsequent physiological course of pregnancy is complicated. Many of those interrelationships are still yet to be discovered. Undoubtedly, their recognition will give hope to infertile couples for the emergence of new treatments that will increase the chance of giving birth to a healthy child.

Expression of trophoblast derived prostaglandin E2 receptor 2 (EP2) is reduced in patients with recurrent miscarriage and EP2 regulates cell proliferation and expression of inflammatory cytokines

BACKGROUD

Prostaglandin E2 (PGE2), an inflammatory mediator, modulates cytokines, regulates immune responses in reproductive processes and stimulates inflammatory reactions via the prostaglandin E2 receptor 2 (EP2). However, the regulatory effects of EP2 signaling on trophoblasts and its role in unexplained recurrent miscarriage (uRM) remains unclear.

PATIENTS AND METHODS

A total of 19 placentas from patients with a history of more than two consecutive pregnancy losses of unknown cause (uRM group) and placentas of 19 healthy patients following a legal termination of their pregnancy were used for PGE2 receptor (EP1, EP2 and EP4) expression analyses via immunohistochemistry. Double immunofluorescence was also used to identify EP2 expressing cells in the decidua. Finally, HTR-8/SVneo cells were used to clarify the role of EP2 in in vitro experiments.

RESULTS

The expression of EP2 and EP4 was found to be reduced in the syncytiotrophoblast and decidua of uRM patients. A selective EP2 receptor antagonist (PF-04,418,948) reduced the proliferation and secretion of ß-hCG, inhibited interleukin -6 (IL-6) and interleukin-8 (IL-8) and up-regulated the production of the tumor necrosis factor-α (TNF-α) and plasminogen activator inhibitor type 1 (PAI-1) in HTR-8/SVneo cells in vitro.

CONCLUSION

PGE2-EP2 signaling pathway may represent a novel therapy option for uRM. The involvement of EP2 in uRM acts perhaps via inflammatory cytokines and indicates that the PGE2-EP2 signaling pathway might represent an unexplored etiology for uRM.

Gene expression and DNA methylation changes in BeWo cells dependent on tumor necrosis factor-α and insulin-like growth factor-I

Pregnant women with increased insulin resistance, characterized by elevated levels of tumor necrosis factor-alpha (TNF-α) and insulin-like growth factor-I (IGF-I), are at high risk of preeclampsia. We hypothesized that TNF-α and IGF-I affect the placentas and cause pathological changes leading to preeclampsia. To understand the genetic and epigenetic effects of TNF-α and IGF-I on trophoblast cells, gene expression microarray and DNA methylation array of BeWo cells stimulated by TNF-α (100 pg/ml, 100 ng/ml) and IGF-I (100 ng/ml) were conducted. Microarray analysis revealed the differential gene expression patterns in BeWo cells co-stimulated by TNF-α and IGF-I. Enrichment analysis identified the terms associated with NF-kappa B signaling pathways and arachidonic acid cascades such as PTGS2 and PTGER2. DNA methylation array revealed the distinct CpG methylation pattern in BeWo cells stimulated by high-TNF-α and IGF-I, while neither of them showed independent effects. Enrichment analysis identified the terms associated with major histocompatibility complex proteins. Integration of transcriptome and DNA methylome analyses identified three differentially expressed genes with significant DNA methylation change: C3, GP1BA, and NFKBIE, which are all possibly associated with pathogenesis of preeclampsia. In conclusion, co-stimulation of TNF-α and IGF-I induced the genetic and epigenetic changes associated with preeclampsia in BeWo cells. The results suggested that BeWo cells stimulated by TNF-α and IGF-I is a good in vitro model of preeclamptic placenta in pregnancy with increased insulin resistance.

Tumor necrosis factor-α regulates angiogenesis of BeWo cells via synergy of PlGF/VEGFR1 and VEGF-A/VEGFR2 axes

OBJECTIVES

Tumor necrosis factor-alpha (TNF- α) promotes tumor growth by enhancing tumor angiogenesis; however, the effects on choriocarcinoma remain unknown. We investigated the effects of TNF-α on the production of placental growth factor (PlGF) and vascular endothelial growth factor-A (VEGF-A) in BeWo cells and also examined its significance on the interactions with the endothelial cells by using human umbilical vein endothelial cells (HUVECs).

MATERIALS & METHODS

After incubation with TNF-α (10-10⁵ pg/mL), the expression of PlGF and VEGF-A in BeWo cells were assessed by ELISA and RT-PCR. HUVEC tube formation assays were conducted to assess the angiogenic activity of the conditioned medium. The phosphorylation status of VEGFR1 and VEGFR2 in HUVECs under the stimulation of the conditioned medium was assessed by immunoprecipitation and immunoblotting. The same experiments were repeated with recombinant PlGF and VEGF-A to confirm the effects of the growth factors.

RESULTS

Low levels (10-10² pg/mL) of TNF-α enhanced the mRNA and protein levels of PlGF, but the changes in VEGF-A levels were not significant. HUVEC tube formation was promoted by the conditioned medium, and those effects were inhibited by the anti-VEGFR1 antibody and PlGF-siRNA. VEGFR2 was significantly phosphorylated by the conditioned medium, while the effect on VEGFR1 phosphorylation was very weak. HUVEC tube formation was incomplete when recombinant PlGF was used; however, the addition of PlGF promoted the effects of VEGF-A. The addition of PlGF along with VEGF-A also stimulated VEGFR2 phosphorylation.

CONCLUSIONS

TNF-α promoted PlGF synthesis in BeWo cells and regulated angiogenesis via synergy of the PlGF/VEGFR1 and VEGF-A/VEGFR2 axes.