IFN-gamma-mediated inhibition of COX-2 expression in the placenta from term and preterm labor pregnancies

A Novel Predictive Machine Learning Model Integrating Cytokines in Cervical-Vaginal Mucus Increases the Prediction Rate for Preterm Birth

Preterm birth (PB) is a leading cause of perinatal morbidity and mortality. PB prediction is performed by measuring cervical length, with a detection rate of around 70%. Although it is known that a cytokine-mediated inflammatory process is involved in the pathophysiology of PB, none screening method implemented in clinical practice includes cytokine levels as a predictor variable. Here, we quantified cytokines in cervical-vaginal mucus of pregnant women (18-23.6 weeks of gestation) with high or low risk for PB determined by cervical length, also collecting relevant obstetric information. IL-2, IL-6, IFN-γ, IL-4, and IL-10 were significantly higher in the high-risk group, while IL-1ra was lower. Two different models for PB prediction were created using the Random Forest machine-learning algorithm: a full model with 12 clinical variables and cytokine values and the adjusted model, including the most relevant variables-maternal age, IL-2, and cervical length- (detection rate 66 vs. 87%, false positive rate 12 vs. 3.33%, false negative rate 28 vs. 6.66%, and area under the curve 0.722 vs. 0.875, respectively). The adjusted model that incorporate cytokines showed a detection rate eight points higher than the gold standard calculator, which may allow us to identify the risk PB risk more accurately and implement strategies for preventive interventions.

The Placental NLRP3 Inflammasome and Its Downstream Targets, Caspase-1 and Interleukin-6, Are Increased in Human Fetal Growth Restriction: Implications for Aberrant Inflammation-Induced Trophoblast Dysfunction

Fetal growth restriction (FGR) is commonly associated with placental insufficiency and inflammation. Nonetheless, the role played by inflammasomes in the pathogenesis of FGR is poorly understood. We hypothesised that placental inflammasomes are differentially expressed and contribute to the aberrant trophoblast function. Inflammasome gene expression profiles were characterised by real-time PCR on human placental tissues collected from third trimester FGR and gestation-matched control pregnancies (n = 25/group). The functional significance of a candidate inflammasome was then investigated using lipopolysaccharide (LPS)-induced models of inflammation in human trophoblast organoids, BeWo cells in vitro, and a murine model of FGR in vivo. Placental mRNA expression of NLRP3, caspases 1, 3, and 8, and interleukin 6 increased (>2-fold), while that of the anti-inflammatory cytokine, IL-10, decreased (<2-fold) in FGR compared with control pregnancies. LPS treatment increased NLRP3 and caspase-1 expression (>2-fold) in trophoblast organoids and BeWo cell cultures in vitro, and in the spongiotrophoblast and labyrinth in the murine model of FGR. However, the LPS-induced rise in NLRP3 was attenuated by its siRNA-induced down-regulation in BeWo cell cultures, which correlated with reduced activity of the apoptotic markers, caspase-3 and 8, compared to the control siRNA-treated cells. Our findings support the role of the NLRP3 inflammasome in the inflammation-induced aberrant trophoblast function, which may contribute to FGR.

IL-27 Mediates Pro-Inflammatory Effects via the ERK Signaling Pathway During Preterm Labor

Preterm labor (PTL) is a multifactorial syndrome that results in birth prior to 37 weeks of gestation. However, the specific molecular mechanisms underlying this condition have yet to be elucidated. Previous research demonstrated that the abnormal expression of IL-27, and its receptors, played a role in the pathophysiology of preterm labor. In the present study, we established a Lipopolysaccharide (LPS)-stimulated, infection-induced, preterm mouse model based on wild-type C57BL/6 mice and WSX-1^-/-C57BL/6 mice. WSX-1 knockdown led to a significant delay in birth by 11.32 ± 2.157h. In addition, compared with wild-type C57B/6 mice, the expression levels of IFN-γ, IL-1β, IL-6, TNF-α, and CXCL10, in the fetal membrane and myometrium of WSX-1^-/-mice were significantly lower, particularly in the myometrium. We also confirmed similar pro-inflammatory effects arising from IL-27 in human amniotic cell line (WISH) and human myometrial smooth muscle cell line (HMSMC). Once stimulated by LPS, the pro-inflammatory action exhibited a synergistic effect and appeared to be time-dependent. Finally, we demonstrated that LY3214996, an inhibitor of the ERK pathway, significantly inhibited the pro-inflammatory effect mediated by IL-27. Overall, our data confirmed that the inflammatory effect mediated by the IL-27/IFN-r/ERK axis is involved in preterm labor. Our findings, therefore, provide an enhancement in our etiological understanding of the mechanisms underlying PTL.

Type 2 and type 3 innate lymphoid cells at the maternal-fetal interface: implications in preterm birth

BACKGROUND

Preterm birth (PTB) is one of the major causes of neonatal morbidity and mortality worldwide. It is commonly accepted that the act of giving birth is the final step in a proinflammatory signaling cascade, orchestrated by an intrauterine milieu coupled to hormonal cues. Consequently, the inflammatory process plays a pivotal role during the pathogenesis of human labor, both in term and preterm deliveries. The ability of innate lymphoid cells (ILCs) to act as pro-inflammatory mediators arose the interest to study their role in normal and pathological pregnancies. The aim of this work was to analyze the relative frequencies of ILCs subsets in pregnancy and the levels of IL-4, IL-17, IL-22, and IFN-γ as inflammatory mediators. Accordingly, we hypothesized that changes in the proportions of ILCs subpopulations could be related to preterm birth.

METHODS

We analyzed 15 full-term delivery samples and six preterm delivery samples. In the full-term group (FTB) peripheral blood was taken during routine blood analysis, on 3 occasions: 1st, 2nd and 3rd trimester. After delivery, peripheral blood, cord blood and placenta were collected. In PTB group, peripheral blood samples were obtained on two occasions: before and 24 h after treatment with progesterone. We used flow cytometry to analyze ILCs in maternal peripheral blood, placenta, and cord blood samples. Maternal peripheral blood and cord blood samples were analyzed by enzyme-linked immunosorbent assay for IL-4, IL-17, IL-22, and IFN-γ plasma levels at the time of labor.

RESULTS

We observed significantly increased relative frequencies of ILC2 and ILC3 in the decidua, as well as an increase of ILC2 in cord blood samples in PTB group, compared to FTB samples. We also found a decrease in IFN-γ in peripheral blood samples of the PTB group, suggesting a functional withdrawal. Additionally, IL-4, IL-17, IL-22 levels were similar in PTB and FTB groups, denoting a relevant role in mediating labor.

CONCLUSION

Our results suggest that ILC2 and ILC3 play a role in PTB by mediating an inflammatory response. Further work is necessary to evaluate the importance of ILCs in the regulation of labor.

Association of genitourinary infections and cervical length with preterm childbirth

A prospective cohort study was conducted on a convenience sample of 1370 pregnant women with a gestational age of 20 to 25 weeks in the city of Ribeirão Preto. Data on obstetrical history, maternal age, parity, smoking habit, and a history of preterm delivery was collected with the application of a sociodemographic questionnaire. Cervical length was determined by endovaginal ultrasound, and urine and vaginal content samples were obtained to determine urinary tract infection (UTI) and bacterial vaginosis (BV), respectively. The aim of this study was to verify the association of cervical length and genitourinary infections with preterm birth (PTB). Ultrasound showed no association of UTI or BV with short cervical length. PTB rate was 9.63%. Among the women with PTB, 15 showed UTI (RR: 1.55, 95%CI: 0.93–2.58), 19 had BV (RR: 1.22, 95%CI: 0.77–1.94), and one had both UTI and BV (RR: 0.85, 95%CI: 0.13–5.62). Nineteen (14.4%) PTB occurred in women with a cervical length ≤2.5 cm (RR: 2.89, 95%CI: 1.89–4.43). Among the 75 patients with PTB stratified as spontaneous, 10 showed UTI (RR: 2.02, 95%CI: 1.05–3.86) and 14 had a diagnosis of BV (RR: 1.72, 95%CI: 0.97–3.04). A short cervical length between 20 and 25 weeks of pregnancy was associated with PTB, whereas UTI and BV determined at this age were not associated with short cervical length or with PTB, although UTI, even if asymptomatic, was related to spontaneous PTB.

Human chorionic gonadotropin-mediated modulation of pregnancy-compatible peripheral blood natural killer cells in frozen embryo transfer cycles

PROBLEM

To evaluate pregnancy-compatible phenotypic and functional changes in peripheral blood natural killer (pNK) cells during frozen embryo transfer (FET) cycles.

METHOD OF STUDY

Peripheral blood was collected from patients undergoing frozen embryo transfer cycles at three separate time points in the cycle. pNK cell phenotype was analyzed by flow cytometry. Impact of pregnancy status on pNK cell cytotoxicity was characterized by two methods: (1) a three-dimensional endovascular tube formation approach and (2) a NK cell-specific K562 cell kill assay.

RESULTS

A total of 35 patients were enrolled, 15 with clinical pregnancies and 20 with negative serum β-hCG levels. Overall percentage of CD45⁺ CD3^- CD56⁺ pNK cell did not change during the FET cycle. Pregnancy resulted in an increase in CD45⁺ CD3^- CD56⁺ pNK cell population on the day of serum β-hCG. pNK cells from non-pregnant patients caused significant tube disruption when compared to pregnant patients. Addition of serum from pregnant women reduced the tube disruption by pNK cells from non-pregnant patients. pNK cells from pregnant patients showed significantly lower cytotoxicity toward K562 cells in serum-free conditions. The addition of pregnancy serum decreased non-pregnant pNK cell cytotoxicity. Pregnancy status had no impact on VEGF-A and VEGF-C serum levels. Recombinant hCG added to non-pregnant serum resulted in a significant reduction in non-pregnant pNK cell-mediated K562 cell kill.

CONCLUSION

There was no difference in pNK cell populations based on timing of the FET cycle. However, pregnancy increased the percentage of CD45⁺ CD3^- CD56⁺ pNK cells. Additionally, pNK cells from pregnant women have reduced cytotoxicity and this is possibly mediated by hCG.

The role of NFκB in the three stages of pregnancy - implantation, maintenance, and labour: a review article

The transcription factor nuclear factor kappa B (NFκB) controls the expression of over 400 genes, some of which are associated with reproductive events. During implantation, immune cells accumulate in the maternal-fetal interface; they secrete inflammatory mediators under the control of NFĸB, the level of which also rises. NFĸB is then downregulated to maintain gestation, but its level rises again before birth to manage prostaglandin, cytokine, and chemokine synthesis, and to stimulate uterine contraction. This review summarises the current state of knowledge about NFκB and its role in the molecular regulation of processes related to pregnancy development.

TWEETABLE ABSTRACT

This review examines the current state of knowledge about role of NFκB in the development of pregnancy.

Madecassoside activates anti‑neuroinflammatory mechanisms by inhibiting lipopolysaccharide‑induced microglial inflammation

Neurodegeneration is typically preceded by neuroinflammation generated by the nervous system to protect itself from tissue damage, however, excess neuroinflammation may inadvertently cause more harm to the surrounding tissues. Attenuating neuroinflammation with non‑steroidal anti‑inflammatory drugs can inhibit neurodegeneration. However, such treatments induce chronic side effects, including stomach ulcers. Madecassoside, a triterpene derived from Centella asiatica, is considered to be an alternative treatment of inflammation. In the present study, the anti‑neuroinflammatory properties of madecassoside were assessed in BV2 microglia cells, which were pre‑treated with madecassoside at a maximum non‑toxic dose (MNTD) of 9.50 µg/ml and a ½ MNTD of 4.75 µg/ml for 3 h and stimulated with 0.1 µg/ml lipopolysaccharide (LPS). The effect of madecassoside was assessed by determining reactive oxygen species (ROS) levels in all groups. Furthermore, the expression of pro‑ and anti‑neuroinflammatory genes and proteins were analyzed using reverse transcription‑quantitative polymerase chain reaction and western blotting, respectively. The results demonstrated that ROS levels in cells treated with the MNTD of madecassoside were significantly reduced compared with cells treated with LPS alone (P<0.05). The expression of pro‑neuroinflammatory genes, including inducible nitric oxide synthase, cyclooxygenase‑2, signal transducer and activator of transcription 1 and nuclear factor‑κB, were significantly downregulated in a dose‑independent manner following treatment with madecassoside. Conversely, the anti‑neuroinflammatory component heme oxygenase 1 was significantly upregulated by 175.22% in the MNTD‑treated group, compared with cells treated with LPS alone (P<0.05). The gene expression profiles of pro‑ and anti‑inflammatory genes were also consistent with the results of western blotting. The results of the present study suggest that madecassoside may be a potent anti‑neuroinflammatory agent. The antioxidative properties of madecassoside, which serve a major role in anti‑neuroinflammation, indicate that this compound may be a functional natural anti‑neuroinflammatory agent, therefore, further in vivo or molecular studies are required.

Differential outcomes of TLR2 engagement in inflammation-induced preterm birth

Preterm birth (PTB) is the leading cause of neonatal mortality worldwide. Infection and inflammation are considered main causes of PTB. Among multiple pathogens, Gram‐positive bacteria are commonly linked with induction of PTB. Although activation of innate immune responses, via TLR2 engagement, by Gram‐positive bacteria is a likely cause, whether induction of PTB depends on the potency of specific microbial components to induce Toll‐like receptor (TLR)2‐driven inflammation has not been elucidated. Here, we show that TLR2 activation by synthetic lipopeptides, Pam2Cys, and Pam3Cys specifically, variably influenced inflammation and subsequent induction of PTB. Pam2Cys challenge, compared to Pam3Cys, induced PTB and promoted significantly higher expression of inflammatory cytokines, specifically IL‐6 and IFN‐β, both in vivo and in vitro. Notably, antibody‐mediated neutralization of IL‐6 or genetic deletion of type I IFN receptor (IFNAR) was sufficient to protect from Pam2Cys‐driven PTB and to temper excessive proinflammatory cytokine production. Conversely, IFN‐β or IL‐6 was not sufficient to promote induction of PTB by Pam3Cys. In summary, our data implies a divergent function of TLR2‐activating lipopeptides in the magnitude and type of ligand‐driven inflammatory vigor in induction of PTB.

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.

Effect of Cytokines on the Formation Tube-Like Structures by Endothelial Cells in the Presence of Trophoblast Cells

Despite ample data on cytokine secretion in the uteroplacental interface, the influence of microenvironment cells, in particular, trophoblast cells on angiogenesis and the role of cytokines in this process remain poorly studied. We studied the influence of cytokines on the formation of tube-like structures by endothelial cells in the presence of trophoblast cells and showed that trophoblast cells suppressed the angiogenic potential of endothelial cells. Antiangiogenic cytokines IFN-γ, IL-10, TNF-α, and TGFβ via modulation of trophoblast cells stimulated the formation of tube-like structures by endothelial cells. In the co-culture of endothelial and trophoblast cells, the effects of cytokines changed and they gained additional regulatory functions.

Eosinophils and Mast Cells in Aspirin-Exacerbated Respiratory Disease

Aspirin-exacerbated respiratory disease (AERD) involves overexpression of proinflammatory mediators, including 5-lipoxygenase and leukotriene C₄ synthase (LTC₄S), resulting in constitutive overproduction of cysteinyl leukotrienes. Mast cells and eosinophils have roles in mediating many of the observed effects. Increased levels of both interleukin-4 (IL-4) and interferon (IFN)-γ are present in the tissue of patients with AERD. Previous studies showed that IL-4 is primarily responsible for the upregulation of LTC₄S by mast cells. Our studies show that IFN-γ, but not IL-4, drives this process in eosinophils. This article examines the overall role that eosinophils and mast cells contribute to the pathophysiology of AERD.

Donor variability among anti-inflammatory pre-activated mesenchymal stromal cells

Therapeutic mesenchymal stromal cells (MSCs) are attractive in part due to their immunomodulatory properties, achieved by their paracrine secretion of factors including prostaglandin E2 (PGE2). Despite promising pre-clinical data, demonstrating clinical efficacy has proven difficult. The current studies were designed to develop approaches to pre-induce desired functions from naïve MSCs and examine MSC donor variability, two factors contributing to this disconnect. MSCs from six human donors were pre-activated with interleukin 1 beta (IL-1β) at a concentration and duration identified as optimal or interferon gamma (IFN-γ) as a comparator. Their secretion of PGE2 after pre-activation and secondary exposure to pro-inflammatory molecules was measured. Modulation of tumor necrosis factor alpha (TNF-α) secretion from M1 pro-inflammatory macrophages by co-cultured pre-activated MSCs was also measured. Our results indicated that pre-activation of MSCs with IL-1β resulted in upregulated PGE2 secretion post exposure. Pre-activation with IL-1β or IFN-γ resulted in higher sensitivity to induction by secondary stimuli compared to no pre-activation. While IL-1β pre-activation led to enhanced MSC-mediated attenuation of macrophage TNF-α secretion, IFN-γ pre-activation resulted in enhanced TNF-α secretion. Donor variability was noted in PGE2 secretion and upregulation and the level of improved or impaired macrophage modulation.

Literature-Informed Analysis of a Genome-Wide Association Study of Gestational Age in Norwegian Women and Children Suggests Involvement of Inflammatory Pathways

Background

Five-to-eighteen percent of pregnancies worldwide end in preterm birth, which is the major cause of neonatal death and morbidity. Approximately 30% of the variation in gestational age at birth can be attributed to genetic factors. Genome-wide association studies (GWAS) have not shown robust evidence of association with genomic loci yet.

Methods

We separately investigated 1921 Norwegian mothers and 1199 children from pregnancies with spontaneous onset of delivery. Individuals were further divided based on the onset of delivery: initiated by labor or prelabor rupture of membranes. Genetic association with ultrasound-dated gestational age was evaluated using three genetic models and adaptive permutations. The top-ranked loci were tested for enrichment in 12 candidate gene-sets generated by text-mining PubMed abstracts containing pregnancy-related keywords.

Results

The six GWAS did not reveal significant associations, with the most extreme empirical p = 5.1 × 10⁻⁷. The top loci from maternal GWAS with deliveries initiated by labor showed significant enrichment in 10 PubMed gene-sets, e.g., p = 0.001 and 0.005 for keywords "uterus" and "preterm" respectively. Enrichment signals were mainly caused by infection/inflammation-related genes TLR4, NFKB1, ABCA1, MMP9. Literature-informed analysis of top loci revealed further immunity genes: IL1A, IL1B, CAMP, TREM1, TFRC, NFKBIA, MEFV, IRF8, WNT5A.

Conclusion

Our analyses support the role of inflammatory pathways in determining pregnancy duration and provide a list of 32 candidate genes for a follow-up work. We observed that the top regions from GWAS in mothers with labor-initiated deliveries significantly more often overlap with pregnancy-related genes than would be expected by chance, suggesting that increased sample size would benefit similar studies.

Interferon-γ stimulates human follicular dendritic cell-like cells to produce prostaglandins via the JAK-STAT pathway

IFN-γ plays a critical role in the regulation of innate and adaptive immunity. Paying attention to the emerging role of prostaglandins (PGs) as immune regulators, we attempted to establish the effect of IFN-γ on PG production in human follicular dendritic cell-like HK cells and the underlying signaling pathway by using RNA interference technology. IFN-γ induced COX-2 protein expression in HK cells in a time- and dose-dependent manner, which was not observed in peripheral blood monocytes. Although IFN-γ induced phosphorylation of STAT1, STAT3, and STAT5, only STAT1 was essential for the COX-2 augmentation. The JAK kinases responsible for IFN-γ-triggered STAT1 phosphorylation were JAK1 and JAK2, which were also required for the COX-2 induction. The essential requirement of JAK1 and JAK2 was verified by confocal microscopic analysis, since STAT1 phosphorylation and nuclear translocation were impaired in HK cells with these two kinases knocked down. Finally, we demonstrated that JAK1, JAK2, and STAT1 were indispensable for the actual enhancement of PG production in response to IFN-γ stimulation. These results provide a novel insight into our understanding of IFN-γ under inflammatory conditions and support the emerging concept of PGs as important immune regulators.

Polybrominated diphenyl ethers enhance the production of proinflammatory cytokines by the placenta

Polybrominated diphenyl ether(s) (PBDE) are ubiquitous environmental contaminants that bind and cross the placenta but their effects on pregnancy outcome are unclear. It is possible that environmental contaminants increase the risk of inflammation-mediated pregnancy complications such as preterm birth by promoting a proinflammatory environment at the maternal-fetal interface. We hypothesized that PBDE would reduce IL-10 production and enhance the production of proinflammatory cytokines associated with preterm labor/birth by placental explants. Second-trimester placental explants were cultured in either vehicle (control) or 2 μM PBDE mixture of congers 47, 99 and 100 for 72 h. Cultures were then stimulated with 10(6) CFU/ml heat-killed Escherichia coli for a final 24 h incubation and conditioned medium was harvested for quantification of cytokines and PGE(2). COX-2 content and viability of the treated tissues were then quantified by tissue ELISA and MTT reduction activity, respectively. PBDE pre-treatment reduced E. coli-stimulated IL-10 production and significantly increased E. coli-stimulated IL-1β secretion. PBDE exposure also increased basal and bacteria-stimulated COX-2 expression. Basal, but not bacteria-stimulated PGE(2), was also enhanced by PBDE exposure. No effect of PBDE on viability of the explants cultures was detected. In summary, pre-exposure of placental explants to congers 47, 99, and 100 enhanced the placental proinflammatory response to infection. This may increase the risk of infection-mediated preterm birth by lowering the threshold for bacteria to stimulate a proinflammatory response(s).

TLR-mediated preterm birth in response to pathogenic agents

The incidence of preterm birth in developed countries has risen in the past decades. Underlying causes for this enigmatic pregnancy complication are numerous, yet infectious agents that induce dysregulation of immunity at the maternal-fetal interface pose one of the most probable causes of preterm birth. This paper highlights two factors regarding maternal infections that trigger unscheduled inflammatory sequences that are deleterious to the maternal-fetal balance necessary to maintain pregnancy. Firstly, we discuss the role of Toll-like receptors (TLRs) as sentinels of uterine immunity in the context of response to pathogens. We highlight the idea that particular TLR activations lead to differential immune cascades that induce preterm birth. Secondly, two alternative routes of pathogenic entry may prove to be critical for inducing preterm birth via a cytokine storm or a secondary and currently unknown cell-mediated mechanism of uterine inflammation. This paper summarizes pathways that underlie activation of adverse and diverse immune responses to foreign agents that may result in preterm birth.

Chronic infection during placental malaria is associated with up-regulation of cycloxygenase-2

BACKGROUND

Placental malaria (PM) is associated with poor foetal development, but the pathophysiological processes involved are poorly understood. Cyclooxygenase (COX) and lipoxygenase (LOX) which convert fatty acids to prostaglandins and leukotrienes, play important roles in pregnancy and foetal development. COX-2, currently targeted by specific drugs, plays a dual role as it associates with both pre-eclampsia pathology and recovery during infection. The role of COX during PM was questioned by quantifying at delivery COX-1, COX-2, 15-LOX, and IL-10 expression in two groups of malaria infected and uninfected placenta.

METHODS

Placental biopsies were collected at delivery for mRNA isolation and quantification, using real time PCR.

RESULTS

COX-2 and IL-10 mRNAs increased mainly during chronic infections (nine- and five-times, respectively), whereas COX-1 transcripts remained constant. COX-2 over-expression was associated with a higher birth weight of the baby, but with a lower rate of haemoglobin of the mother. It was associated with a macrophage infiltration of the placenta and with a low haemozoin infiltration. In the opposite way, placental infection was associated with lower expression of 15-LOX mRNA. A high degree of haemozoin deposition correlates with low birth weight and decreased expression of COX-2.

CONCLUSION

These data provide evidence that COX-2 and IL-10 are highly induced during chronic infection of the placenta, but were not associated with preterm delivery or low birth weight. The data support the involvement of COX-2 in the recovery phase of the placental infection.

Recent findings on the pathogenesis of bronchial asthma. Part II. The role of hormonal predisposition, environmental influences and conditioning leading to bronchial asthma

In this second part of the review on the pathogenesis of asthma the hormonal factors and adverse external events are shortly reviewed which skew the balance of Th1 vs. Th2 CD4+ lymphocytes towards the latter ones and this way increase the probability of atopic diseases. Among other the role of transplacental priming, insulin, insulin-like and other growth factors, lack of the usual microbial infections in the early childhood (the so-called hygiene hypothesis), gender, diminished testosterone production, gastroesophageal reflux, adverse effects during pregnancy are discussed. A separate chapter deals with the role of central nervous system in the etiology and finally the most common allergizing and airway tissue damaging agents are listed in tabulated form.

Interferon gamma in successful pregnancies

Interferon gamma (IFNG) is a proinflammatory cytokine secreted in the uterus during early pregnancy. It is abundantly produced by uterine natural killer cells in maternal endometrium but also by trophoblasts in some species. In normal pregnancies of mice, IFNG plays critical roles that include initiation of endometrial vasculature remodeling, angiogenesis at implantation sites, and maintenance of the decidual (maternal) component of the placenta. In livestock and in humans, deviations in these processes are thought to contribute to serious gestational complications, such as fetal loss or preeclampsia. Interferon gamma has broader roles in activation of innate and adaptive immune responses to viruses and tumors, in part through upregulating transcription of genes involved in cell cycle regulation, apoptosis, and antigen processing/presentation. Despite this, rodent and human trophoblast cells show dampened responses to IFNG that reflect the resistance of these cells to IFNG-mediated activation of major histocompatibility complex (MHC) class II transplantation antigen expression. Lack of MHC class II antigens on trophoblasts is thought to facilitate survival of the semiallogeneic conceptus in the presence of maternal lymphocytes. This review describes the dynamic roles of IFNG in successful pregnancy and briefly summarizes data on IFNG in gestational pathologies.

Expression and activity of Toll-like receptors 1-9 in the human term placenta and changes associated with labor at term

Inflammatory processes are involved in the initiation and maintenance of labor, suggesting that Toll-like receptor (TLR) activity within gestation-associated tissues, such as the placenta, might contribute to the process of parturition. Expression of transcripts for TLR1-TLR10 was examined in term (>37 wk of gestation) human placentas collected in the absence of labor (elective caesarean sections; ECS; n = 11) and after the completion of labor (normal vaginal delivery; NVD; n = 12). Placental explants were cultured in the presence of agonists for TLR2, TLR3, TLR4, TLR5, TLR7, TLR8, and TLR9, and cytokine production after 24 h was examined. All placentas expressed transcripts for TLR1-TLR10. Reactivity to all agonists except CpG oligonucleotides was observed, indicating that, other than TLR9, all of the receptors studied yielded functional responses. Placental explants prepared from NVD placentas (n = 17) produced significantly more TNFA in response to lipopolysaccharide (TLR4 agonist) and resiquimod (TLR7/8 agonist) than explants from ECS placentas (n = 17). In contrast, gene expression analysis revealed that only transcripts for TLR2 and TLR5 were significantly elevated in association with labor. The human term placenta expresses a variety of functional TLRs, indicating that this family of receptors has an important role in parturition via as yet undetermined cell types and signaling pathways.

Variations in cervical IL-10 and IL-8 concentrations throughout gestation in normal pregnancies

PROBLEM

Data regarding cervical interleukin 18 (IL-8) and IL-10 concentrations during pregnancy is limited.

METHOD OF STUDY

This was a cross sectional study of healthy pregnant women. Specimens were collected from the cervical os secretions. IL-8 and IL-10 levels were measured by using enzyme-linked immunosorbent assay. Median (range) cytokine concentrations were derived for each trimester and compared across trimesters. The relationship between gestational age and cytokine levels was assessed by regression analysis. The mean of the ratios of IL-8 to IL-10 was compared in each trimester using anova.

RESULTS

The median (range) IL-8 concentrations in cervical secretions were in pg/mL: 1562 (1210-4100), 2460 (1047-4688), 3660 (1451-4748) (P < 0.0021); the median (range) IL-10 concentrations in cervical secretions were in pg/mL: 38.3 (6.8-227.9), 10.9 (0-263.3), 9.5 (0-35.6); the mean IL10/IL-8 x 100 (+/- standard deviation) concentrations were: 3.33 +/- 0.65, 1.47 +/- 0.41, 0.38 +/- 0.52 (P = 0.0035) during the first, second and third trimesters, respectively.

CONCLUSION

The patterns of cervical IL-8 concentration is inversely related to gestational age, and the ratio of IL-10/IL-8 decreases with advancing gestation.

Several transcription factors regulate COX-2 gene expression in pancreatic beta-cells

Cyclooxygenase-2 (COX-2) expression is associated with many aspects of physiological and pathological conditions, including pancreatic beta-cell dysfunction. Prostaglandin E2 (PGE2) production, as a consequence of COX-2 gene induction, has been reported to impair beta-cell function. The molecular mechanisms involved in the regulation of COX-2 gene expression are not fully understood. In this report, we used pancreatic beta-cells (RINm5F) to explore the potential transcription factors regulating COX-2 promoter activity. Using promoter screening method, we selected several transcription factors in our study. Through luciferase reporter studies, we found that these factors can regulate COX-2 promoter activity in RINm5F cells. Among these factors, cyclic AMP response-element binding protein (CREB), Ets family members Ets-1 and Elk-1 can positively regulate COX-2 promoter activity. On the contrary, signal transducer and activator of transcription 1 (STAT1) plays a negative role on COX-2 promoter. Our findings will be helpful for better understanding the transcriptional regulation of COX-2 in pancreatic beta-cells. Moreover, these transcriptional regulators of COX-2 expression will be potential targets for the prevention of beta-cell damage mediated by PGE2.

STAT1-independent inhibition of cyclooxygenase-2 expression by IFNgamma; a common pathway of IFNgamma-mediated gene repression but not gene activation

Cyclooxygenase-2 (COX-2), the rate-limiting enzyme in the synthesis of prostaglandins, promotes the development of colorectal cancer, and is a key molecular target of non-steroidal anti-inflammatory drugs, compounds that reduce the relative risk of developing colon cancer. In this study, we showed that interferon gamma (IFNgamma) inhibits the expression of COX-2 protein in intestinal epithelial cells (IECs) through a pathway that requires Janus-activated kinase (JAK) activity. In contrast, we demonstrated that transcriptional inhibition of COX-2 by IFNbeta or IFNgamma occurs in cells with silenced signal transducer and activator of transcription 1 (STAT1) expression and that IFNs retained the ability to inhibit COX-2 transcription in cells with activated RasV12, in which IFNgamma failed to induce STAT1. Thus, unlike the activity of JAK, STAT1 is not required for the inhibition of COX-2 expression by IFNgamma. In contrast to COX-2, the activation of genes in response to IFNgamma, such as interferon regulatory factor-1, was severely impaired by both STAT1 silencing and by constitutive Ras signaling. To determine whether there is a general differential requirement for STAT1 in gene activation and gene repression in response to IFNgamma in intestinal cells, we performed genome-wide analysis of IFNgamma target genes in an IEC line in which STAT1 expression was silenced by small interfering RNA. The results confirmed that the activation of the majority of genes by IFNgamma required STAT1. In contrast, the repression of several genes, as we showed for COX-2 specifically, was largely unaffected in cells with silenced STAT1. Our results therefore demonstrate that in general gene activation by IFNgamma is more sensitive to STAT1 deficiency than gene repression, and suggest that IFNgamma activates and represses gene expression via distinct pathways that can be distinguished, at least in part, by their requirement for STAT1.

Soluble factors from LPS- and PHA-activated PBMC induce MAPK, Stat1 and Stat3 phosphorylation in primary cultures of human term placental trophoblasts: implications for infection and prematurity

Infection of the maternal vaginal tract is one of the single most important antecedents of premature labor. We have hypothesized that the abundant local synthesis of pro-inflammatory cytokines that occurs during infection may disrupt the delicate "immunological cross-talk" that must occur between maternal and fetal tissues in order to carry pregnancy to term. These experiments were undertaken as part of a larger study directed at testing that hypothesis. We prepared primary cultures of human trophoblasts from term placentas. Cell cultures were stimulated with conditioned medium from resting, PHA or LPS-activated peripheral blood mononuclear cells (PBMC). Medium with LPS or PHA at the same concentration as that used to stimulate the PBMC was used as an additional control. Lysates were subjected to western blotting for activated forms of the mitogen-activated protein kinases (MAPK), Stat1, and Stat3. Western blotting showed phosphorylation of the Jun kinase (JNK), p38, and Erk1/Erk2 MAPK in trophoblasts incubated with conditioned medium from LPS or PHA-activated PBMC but not from medium from resting PBMC, or with PHA or LPS alone. Phosphorylation could be detected as early as 5 min and was still observable by 10 min, the latest time point tested. Similarly, Stat1 and Stat3 phosphorylation was observed within 10 min of exposure to conditioned medium and was still observable 10 min after exposure. Immunohistochemistry also demonstrated nuclear translocation of both Stat1 and Stat3 after stimulation of trophoblasts with medium from activated PBMC. These findings are compatible with the hypothesis that immunologic balance at the maternal-fetal interface is maintained by ongoing "cross-talk" between the fetus (and fetally-derived tissues) and the maternal immune system. Infection of the maternal vaginal tract may disrupt this delicate immunologic balance, initiating inflammatory events that ultimately result in preterm labor.

Cytokine secretion in decidual mononuclear cells from term human pregnancy with or without labour: ELISPOT detection of IFN-gamma, IL-4, IL-10, TGF-beta and TNF-alpha

Cytokines are believed to be important in maintaining pregnancy and in the process of labour induction in humans. The aim of this study was to investigate the secretion of the cytokines interferon-gamma (IFN-gamma), interleukin-4 (IL-4), IL-10, transforming growth factor-beta (TGF-beta) and tumour necrosis factor-alpha (TNF-alpha) in decidual tissue with or without labour. Decidual tissue was collected from 32 healthy women undergoing elective caesarean sections before the onset of labour (n=17) or after normal vaginal delivery (n=15). Mononuclear cells were analysed for cytokine secretion with ELISPOT. To validate the widely used method of tissue collected at caesarean sections and after vaginal deliveries as a representative of before and after labour, respectively, placenta biopsies were collected from 12 healthy women to study the expression of the prostaglandin pathway enzymes cyclooxygenase-2 (COX-2) and microsomal prostaglandin E(2) synthase (mPGES). Decidual mononuclear cells from term human pregnancy spontaneously secrete IFN-gamma, IL-4, IL-10, TGF-beta and TNF-alpha. No difference was seen in cytokine secretion with or without labour, indicating that decidual leukocytes are not the main cell population responsible for plausible cytokine regulation in the process of termination of pregnancy. Placental tissues obtained after vaginal delivery showed a higher mRNA expression of the prostaglandin regulating molecules COX-2 and mPGES than tissues from caesarean sections before the onset of labour, validating that the model can be used as a representative of the state before and after labour.

Evidence for interleukin-10-mediated inhibition of cyclo- oxygenase-2 expression and prostaglandin production in preterm human placenta

PROBLEM

Interleukin-10 (IL-10) is thought to be a key cytokine for the maintenance of pregnancy. Here we examined the expression profiles of IL-10 and cyclo-oxygenase-2 (COX-2), and the effect of IL-10 on COX-2 expression and prostaglandin release in the human placenta from preterm labor deliveries associated with chorioamnionitis.

METHOD OF STUDY

Placental tissues from preterm labor and term labor deliveries were processed for ex vivo placental explant culture system. IL-10 expression was assessed by enzyme-linked immunosorbent assay (ELISA) and immunohistochemical (IHC) analysis. COX-2 expression was evaluated by IHC, Western blotting and reverse transcriptase-polymerase chain reaction. Prostaglandin E2 (PGE2) release was measured by ELISA.

RESULTS

IL-10 was significantly reduced in chorioamnionitis-associated preterm labor as well as in term labor placental tissues compared with second trimester normal pregnancy samples obtained from elective terminations. Similar results were obtained with freshly isolated cytotrophoblasts from these deliveries. As expected, COX-2 mRNA was detected at significant levels in tissues from term and preterm labor deliveries compared with no labor term deliveries. Importantly, IL-10 inhibited COX-2 expression in cultured placental explants from preterm labor deliveries, but not from term labor samples. Inhibition of COX-2 expression coincided with reduced PGE2 release.

CONCLUSION

These results demonstrate the importance of IL-10 in countering inflammation associated with preterm labor, and suggest that term and preterm parturition may, in part, represent different conditions.