Incubation of human chorioamniotic membranes with Candida albicans induces differential synthesis and secretion of interleukin-1beta, interleukin-6, prostaglandin E, and 92 kDa type IV collagenase

Culture of Human Fetal Membranes in a Two Independent Compartment Model: An Ex Vivo Approach

During pregnancy, the fetal membranes composed of the amnion and chorodecidua constitute a selective barrier separating two distinct environments, maternal and fetal. These tissues have the function of delimiting the amniotic cavity. Their histological complexity gives them physical, mechanical, and immunological properties to protect the fetus. Although the study of the amnion, chorion, and decidua separately provides knowledge about the functions of the fetal membranes, the protocol we describe in this chapter has the advantage of maintaining the biological and functional complexity of these tissues. In addition, this experimental model allows the researcher to recreate various pathological scenarios because this model allows for differential stimulation of the amnion or choriodecidua.

Progesterone-mediated immunoregulation of cytokine signaling by miRNA-133a and 101-3p in Chlamydia trachomatis-associated recurrent spontaneous abortion

miRNAs regulate the expression of various genes involved in cellular and metabolic pathways in pregnancy related complications including recurrent spontaneous abortion (RSA). Modulation of progesterone and associated pro-inflammatory cytokines by miRNAs in Chlamydia trachomatis-associated RSA is still under investigation. Present study aimed to evaluate the expression/correlation of serum-circulating miRNAs-133a, 101-3p, 320b, 146b-5p, 24, 559, progesterone and few cytokines in C. trachomatis-positive spontaneous aborters. Non-heparinized blood and urine was collected from 120 patients with history of RSA (Group I) and 120 patients with ≥ 2 successful deliveries (Group II) attending Department of Obstetrics and Gynecology, Safdarjung hospital, New Delhi, India. C. trachomatis detection was performed by PCR and chlamydial load by real time PCR. Progesterone concentration was estimated by ELISA. miRNAs and cytokine expression was studied by quantitative real-time PCR and correlated with progesterone expression. Twenty six patients were found to be positive for C. trachomatis. miRNAs- 133a, 101-3p showed maximum upregulation in infected versus control patients. miRNA expression showed positive correlation with chlamydial load. Progesterone concentration showed significant decrease while cytokines (IL-6, IFN-γ, TNF-α) were significantly upregulated in C. trachomatis-positive patients. Positive correlation was observed between expression of miRNAs-133a and 101-3p and cytokines while negative correlation was observed with progesterone in infected RSA patients. Correlation between progesterone and cytokines was found to be significantly negative in infected RSA patients. Although further validation is required, the study concludes that miR-133a and 101-3p are of clinical importance and have a role in immunoregulation of progesterone and cytokines in infection associated RSA.

The serotonin reuptake inhibitor fluoxetine induces human fetal membrane sterile inflammation through p38 MAPK activation

Serotonin Reuptake Inhibitors (SRIs) are often used as first line therapy for depression and other psychiatric disorders. SRI use during pregnancy is associated with preterm premature rupture of membranes (PPROM) and subsequent preterm birth. The objective of this study was to investigate the mechanism(s) responsible for SRI-associated PPROM. Putative mechanisms underlying PPROM include fetal membrane (FM) inflammation, increased apoptosis, and/or accelerated senescence, the later which may be reversed by statins. Human FM explants from normal term deliveries without labor, infection, or antidepressant use were treated with or without the SRI, fluoxetine (FLX), either alone or in the presence of a p38 MAPK inhibitor or the statins, simvastatin or rosuvastatin. FMs were also collected from women either unexposed or exposed to FLX during pregnancy. FLX significantly increased FM p38 MAPK activity and secretion of inflammatory IL-6. Inhibition of p38 MAPK reduced FM IL-6 secretion in response to FLX. Statins did not reduce the SRI-induced FM IL-6 production. FMs from women exposed to FLX during pregnancy expressed elevated levels of p38 MAPK activity compared to matched unexposed women. FMs exposed to FLX did not exhibit signs of increased apoptosis and/or accelerated senescence. These results indicate that the SRI, FLX, may induce sterile FM inflammation during pregnancy through activation of the p38 MAPK pathway, and in the absence of apoptosis and senescence. These findings may better inform clinicians and patients as they weigh the risks and benefits of SRI antidepressant treatment during pregnancy.

Matrix metalloproteinases in preterm prelabor rupture of membranes in the setting of chorioamnionitis: A scoping review

Fetal or gestational membranes extend from the placenta to enclose the fetus and amniotic fluid. While the membranes spontaneously rupture at term in normal pregnancies, they can rupture prematurely before the onset of labor, termed preterm prelabor rupture of membranes (PPROM). PPROM can be triggered by bacterial infection or sterile inflammation in the membranes, known as chorioamnionitis (CAM). The membranes derive their tensile strength from a collagen-rich extracellular matrix (ECM); as such, understanding the enzymes and processes that can degrade the membrane ECM are of paramount importance. Matrix metalloproteinases (MMPs) are a class of enzymes capable of degrading collagen and other components of the ECM, and can be induced by inflammation. We used a scoping review to address the question of how MMP activity is associated with PPROM, particularly their induction due to sterile or nonsterile CAM. We have found that the most studied MMPs in PPROM were MMPs 2, 8, and 9. Additionally, some MMPs are constitutively active, while others are induced by inflammation. Mechanistic studies of the pathways that induce MMP activation are sparse, and this area is ripe for future studies. Targeting MMP activation could be a future strategy to delay or prevent PPROM.

Modeling ascending infection with a feto-maternal interface organ-on-chip

Maternal infection (i.e., ascending infection) and the resulting host inflammatory response are risk factors associated with spontaneous preterm birth (PTB), a major pregnancy complication. However, the path of infection and its propagation from the maternal side to the fetal side have been difficult to study due to the lack of appropriate in vitro models and limitations of animal models. A better understanding of the propagation kinetics of infectious agents and development of the host inflammatory response at the feto-maternal (amniochorion-decidua, respectively) interface (FMi) is critical in curtailing host inflammatory responses that can lead to PTB. To model ascending infection and determine inflammatory responses at the FMi, we developed a microfluidic organ-on-chip (OOC) device containing primary cells from the FMi (decidua, chorion, and amnion [mesenchyme and epithelium]) and collagen matrix harvested from primary tissue. The FMi-OOC is composed of four concentric circular cell/collagen chambers designed to mimic the thickness and cell density of the FMi in vivo. Each layer is connected by arrays of microchannels filled with type IV collagen to recreate the basement membrane of the amniochorion. Cellular characteristics (viability, morphology, production of nascent collagen, cellular transitions, and migration) in the OOC were similar to those seen in utero, validating the physiological relevance and utility of the developed FMi-OOC. The ascending infection model of the FMi-OOC, triggered by exposing the maternal (decidua) side of the OOC to lipopolysaccharide (LPS, 100 ng mL-1), shows that LPS propagated through the chorion, amnion mesenchyme, and reached the fetal amnion within 72 h. LPS induced time-dependent and cell-type-specific pro-inflammatory cytokine production (24 h decidua: IL-6, 48 h chorion: GM-CSF and IL-6, and 72 h amnion mesenchyme and epithelium: GM-CSF and IL-6). Collectively, this OOC model and study successfully modeled ascending infection, its propagation, and distinct inflammatory response at the FMi indicative of pathologic pathways of PTB. This OOC model provides a novel platform to study physiological and pathological cell status at the FMi, and is expected to have broad utility in the field of obstetrics.

In vitro progesterone modulation on bacterial endotoxin-induced production of IL-1β, TNFα, IL-6, IL-8, IL-10, MIP-1α, and MMP-9 in pre-labor human term placenta

BACKGROUND

During human pregnancy, infection/inflammation represents an important factor that increases the risk of developing preterm labor. The purpose of this study was to determine if pre-treatment with progesterone has an immunomodulatory effect on human placenta production of endotoxin-induced inflammation and degradation of extracellular matrix markers.

METHODS

Placentas were obtained under sterile conditions from pregnancies delivered at term before the onset of labor by cesarean section. Explants from central cotyledons of 10 human placentas were pre-treated with different concentrations of progesterone (0.01, 01, 1.0 μM) and then stimulated with 1000 ng/mL of LPS of Escherichia coli. Cytokines TNFα, IL-1β, IL-6, IL-8, MIP-1α, IL-10 concentrations in the culture medium were then measured by specific ELISA. Secretion profile of MMP-9 was evaluated by ELISA and zymogram. Statistical differences were determined by one-way ANOVA followed by the appropriate ad hoc test; P < 0.05 was considered statistically significant.

RESULTS

In comparison to the explants incubated with vehicle, the LPS treatment led to a significant increase in the level of all cytokines. In comparison to the explants treated only with LPS, pre-treatment with 0.01-1.0 μM progesterone significantly blunted (73, 56, 56, 75, 25, 48 %) the secretion of TNF-α, IL-1β, IL-6, IL-8, MIP-1α, IL-10, respectively. The MMP-9 induced by LPS treatment was inhibited only with the highest concentration of progesterone. Mifepristone (RU486) blocked the immunosuppressive effect of progesterone.

CONCLUSIONS

The present results support the concept that progesterone could be part of the compensatory mechanism that limits the inflammation-induced cytotoxic effects associated with an infection process during gestation.

Evidence of an immunosuppressive effect of progesterone upon in vitro secretion of proinflammatory and prodegradative factors in a model of choriodecidual infection

OBJECTIVE

To evaluate whether progesterone (P4) is able to modulate the secretion of tumour necrosis factor α (TNF-α), interleukin-1β (IL-1β), IL-6, IL-8, IL-10 and matrix metalloproteinase-9 (MMP-9) after choriodecidual stimulation with lipopolysaccharide (LPS).

DESIGN

Chorioamnionitis-elicited preterm delivery is associated with an uncontrolled secretion of proinflammatory cytokines that may induce MMPs, which modify the fine immunological and structural equilibrium at the fetal-maternal interface.

SETTING

Instituto Nacional de Perinatología 'Isidro Espinosa de los Reyes', Mexico City.

SAMPLE

Twelve human fetal membranes at term from healthy patients were placed in a two-chamber culture system.

METHODS

Choriodecidual and amniotic regions were preincubated with 1.0, 0.1, or 0.01 μmol/l P4 for 24 hours; after which the choriodecidual region was costimulated with 1000 ng/ml of LPS for 24 hours.

MAIN OUTCOME MEASURES

Descriptive statistics were obtained for each variable. Data distribution was tested for normality using Kolmogorov-Smirnoff and Shapiro-Wilk tests. When distribution was normal, Student's t test was used to analyse for differences among groups. Mann-Whitney's U test was used when data were not normally distributed.

RESULTS

Pretreatment with 1.0 μmol/l P4 significantly blunted the secretion of TNF-α, IL-1β, IL-6, IL-8 and IL-10. MMP-9 was inhibited with 0.1 μmol/l P4. Mifepristone (RU486) blocked the immunosuppressive effect of P4, suggesting a P4 effect mediated by its receptor.

CONCLUSION

These results offer evidence to support the concept that P4 can protect the fetal-placental unit through a compensatory mechanism that partially limits the secretion of proinflammatory and prodegradative modulators.

Human fetal membranes generate distinct cytokine profiles in response to bacterial Toll-like receptor and nod-like receptor agonists

Bacterial infection-associated inflammation is thought to be a major cause of preterm premature rupture of membranes. Proinflammatory cytokines, such as interleukin 1B (IL1B), can weaken fetal membranes (FM) by upregulating matrix metalloproteinases and inducing apoptosis. The mechanism by which infection leads to inflammation at the maternal-fetal interface and subsequent preterm birth is thought to involve innate immune pattern recognition receptors (PRR), such as the Toll-like receptors (TLR) and Nod-like receptors (NLR), which recognize pathogen-associated molecular patterns (PAMPs). The objective of this study was to determine the cytokine profile generated by FMs in response to the bacterial TLR and NLR agonists peptidoglycan (PDG; TLR2), lipopolysaccharide (LPS; TLR4), flagellin (TLR5), CpG ODN (TLR9), iE-DAP (Nod1), and MDP (Nod2). PDG, LPS, flagellin, iE-DAP, and MDP triggered FMs to generate an inflammatory response, but the cytokine profiles were distinct for each TLR and NLR agonist, and only IL1B and RANTES were commonly upregulated in response to all five PAMPs. CpG ODN, in contrast, had a mild stimulatory effect only on MCP-1 and primarily downregulated basal FM cytokine production. IL1B secretion induced by PDG, LPS, flagellin, iE-DAP, and MDP was associated with its processing. Furthermore, FM IL1B secretion in response to TLR2, TLR4, and TLR5 activation was caspase 1-dependent, whereas Nod1 and Nod2 induced IL1B secretion independent of caspase 1. These findings demonstrate that FMs respond to different bacterial TLR and NLR PAMPs by generating distinct inflammatory cytokine profiles through distinct mechanisms that are specific to the innate immune PRR activated.

Tissue-specific IL-10 secretion profile from term human fetal membranes stimulated with pathogenic microorganisms associated with preterm labor in a two-compartment tissue culture system

OBJECTIVE

Interleukin (IL)-10 is a cytokine with anti-inflammatory properties that plays pivotal roles in immune recognition and maintenance of pregnancy, limiting the harmful effects of pro-inflammatory modulators. The aim of this work was to characterize the contribution of amnion and choriodecidua regions of the human fetal membranes in the production of IL-10 after selective stimulation with Candida albicans, Gardnerella vaginalis and Streptococcus agalactiae.

METHODS

Pre-labor human fetal membranes were cultured in a two-compartment tissue culture system and stimulated with 1 × 10(6) CFU/ml of each pathogen added to either the amniotic or choriodecidual region or both.

RESULTS

Candida albicans and G. vaginalis were the pathogens most effective in inducing IL-10 secretion, increasing 20 and 10 times, respectively, the levels of this cytokine in the choriodecidual compartment. Stimulation with S. agalactiae was effective only in the choriodecidual region, increasing two times IL-10 concentration.

CONCLUSIONS

Synthesis and secretion of IL-10 in response to three different pathogens associated with intrauterine infection and preterm birth are differential and depend on the nature of the microorganism and initial contact region.

Progesterone elicits an inhibitory effect upon LPS-induced innate immune response in pre-labor human amniotic epithelium

PROBLEM

Infection of human fetal membranes elicits secretion of pro-inflammatory modulators through its innate immune capacities. We investigated the effect of lipopolysacharide (LPS) and progesterone (P4) upon expression of TLR-4/MyD88, TNFα, IL-6, IL-8, IL-10, and HBD2 on the human amniotic epithelium.

METHOD OF STUDY

Explants of the human amniotic epithelium were pre-treated with 0.01, 0.1, and 1.0 μM of P4; then cotreated with 1000 ng/mL LPS. TLR-4 was immuno-detected, and concentrations of MyD88, TNFα, IL-6, IL-8, IL-10, and HBD2 were quantified by ELISA.

RESULTS

P4 significantly reduced the expression of LPS-induced TLR-4/MyD88. LPS increased the concentrations of TNFα, IL-6, IL-8, IL-10, and HBD2 by factors of 30-, eight, three, three, and fivefold, respectively. P4 at 1.0 μM was the most effective dose to blunt the secretion of TNFα, IL-6, and HBD-2. RU-486 blocks the effect of P4.

CONCLUSION

P4 inhibited LPS-induced TLR-4/MyD88 and pro-inflammatory factors in the human amniotic epithelium. These results could explain partially how P4 can protect the amniotic region of fetal membranes and generate a compensatory mechanism that limits the secretion of pro-inflammatory modulators, which could jeopardize the immune privilege during pregnancy.

Bacterial modulation of human fetal membrane Toll-like receptor expression

PROBLEM

Preterm premature rupture of fetal membranes (pPROM) occurs in 30-40% of spontaneous preterm births (PTB) and is associated with intra-amniotic infection and inflammation. The membranes may sense and respond to microbes via Toll-like receptors (TLRs); however, little is known about their expression and regulation in this tissue. The objective of this study was to evaluate the expression of TLRs 1-10 in fetal membranes after exposure to pathogens associated with intra-amniotic infection and PTB.

METHOD OF STUDY

Normal human term fetal membrane explants were exposed to various bacteria. After 24 hrs, RNA was extracted and quantitative RT-PCR performed for TLRs1-10.

RESULTS

Treatment of fetal membranes with Mycoplasma hominis increased expression of TLR4, TLR6, and TLR8 mRNA. Ureaplasma parvum upregulated TLR8 mRNA, and Porphyromonas gingivalis significantly increased fetal membrane TLR7 expression. In contrast, treatment with Gram-negative Escherichia coli (and its cell wall component lipopolysaccharide) downregulated TLR10 mRNA. No effect was detected for Ureaplasma urealyticum, Gardnerella vaginalis, or Group B Streptococcus.

CONCLUSION

These findings demonstrate that different types of bacteria have distinct effects on fetal membrane TLR expression patterns. Moreover, these findings highlight the disparity of fetal membrane responses to infection and thus suggest heterogeneity in the mechanisms by which infection-associated pregnancy complications, such as pPROM and PTB, arise.

Tissue-specific human beta-defensins (HBD)-1, HBD-2 and HBD-3 secretion profile from human amniochorionic membranes stimulated with Candida albicans in a two-compartment tissue culture system

BACKGROUND

During intrauterine infection, amniochorionic membranes represent a mechanical and immunological barrier against dissemination of infection. Human beta defensins (HBD)-1, HBD-2, and HBD-3 are key elements of innate immunity that represent the first line of defense against different pathogen microorganisms associated with preterm labor. The aim of this work was to characterize the individual contribution of the amnion (AMN) and choriodecidua (CHD) regions to the secretion of HBD-1, HBD-2 and HBD-3, after stimulation with Candida albicans.

METHODS

Full-thickness human amniochorionic membranes were obtained after delivery by elective cesarean section from women at 37-40 wk of gestation with no evidence of active labor. The membranes were cultured in a two-compartment experimental model in which the upper compartment is delimited by the amnion and the lower chamber by the choriodecidual membrane. One million of Candida albicans were added to either the AMN or the CHD face or to both and compartmentalized secretion profiles of HBD-1, HBD-2, and HBD-3 were quantified by ELISA. Tissue immunolocalization was performed to detect the presence of HBD-1, -2, -3 in tissue sections stimulated with Candida albicans.

RESULTS

HBD-1 secretion level by the CHD compartment increased 2.6 times (27.30 [20.9-38.25] pg/micrograms protein) when the stimulus with Candida albicans was applied only on this side of the membrane and 2.4 times (26.55 [19.4-42.5] pg/micrograms protein) when applied to both compartments simultaneously. HBD-1 in the amniotic compartment remained without significant changes. HBD-2 secretion level increased significantly in the CHD when the stimulus was applied only to this region (2.49 [1.49-2.95] pg/micrograms protein) and simultaneously to both compartments (2.14 [1.67- 2.91] pg/micrograms protein). When the stimulus was done in the amniotic compartment HBD-2 remained without significant changes in both compartments. HBD-3 remained without significant changes in both compartments regardless of the stimulation modality. Localization of immune-reactive forms of HBD-1, HBD-2, and HBD-3 was carried out by immunohistochemistry confirming the cellular origin of these peptides.

CONCLUSION

Selective stimulation of amniochorionic membranes with Candida albicans resulted in tissue-specific secretion of HBD-1 and HBD-2, mainly in the CHD, which is the first region to become infected during an ascending infection.

Placental implications of peroxisome proliferator-activated receptors in gestation and parturition

The placenta is a transitory structure indispensable for the proper development of the embryo and fetus during mammalian gestation. Like other members of the nuclear receptor family, the peroxisome proliferator-activated receptors (PPARs) are known to be involved in the physiological and pathological events occurring during the placentation. This placental involvement has been recently reviewed focusing on the early stages of placental development (implantation and invasion, etc.), mouse PPARs knockout phenotypes, and cytotrophoblast physiology. In this review, we describe the placental involvement of PPARs (e.g., fat transport and metabolism, etc.) during the late stages of gestation and in the amniotic membranes, highlighting their roles in the inflammation process (e.g., chorioamnionitis), metabolic disorders (e.g., diabetes), and parturition.

In vitro secretion profile of pro-inflammatory cytokines IL-1β, TNF-α, IL-6, and of human beta-defensins (HBD)-1, HBD-2, and HBD-3 from human chorioamniotic membranes after selective stimulation with Gardnerella vaginalis

PROBLEM

Preterm labor associated with infection is a major clinical condition; in this work, we analyze the response of human chorioamniotic membranes stimulated with Gardnerella vaginalis.

METHOD OF STUDY

Using a two-compartment experimental model, 1 × 10(6) CFU/mL of G. vaginalis were added to either the amnion or choriodecidua face or to both. Concentrations of IL-1β, TNF-α, and IL-6, as well as human beta defensins (HBD) 1-3 were quantified by ELISA.

RESULTS

In comparison with control conditions and regardless of the stimulation modality, IL-1β and IL-6 increased 4-fold and 28-fold, respectively, in the choriodecidual compartment. HBD-1 increased 2-fold mainly in the amniotic compartment when the stimulus was applied directly to this region. HBD-2 and HBD-3 increased an average of 2- and 8-fold, respectively, in the choriodecidual region.

CONCLUSIONS

Stimulation with G. vaginalis induced a tissue-specific secretion profile of 1L-1β, IL-6, and HBD 1-3 in the chorioamniotic membranes.

Protocol for a randomised controlled trial of treatment of asymptomatic candidiasis for the prevention of preterm birth [ACTRN12610000607077]

Background

Prevention of preterm birth remains one of the most important challenges in maternity care. We propose a randomised trial with: a simple Candida testing protocol that can be easily incorporated into usual antenatal care; a simple, well accepted, treatment intervention; and assessment of outcomes from validated, routinely-collected, computerised databases.

Methods/Design

Using a prospective, randomised, open-label, blinded-endpoint (PROBE) study design, we aim to evaluate whether treating women with asymptomatic vaginal candidiasis early in pregnancy is effective in preventing spontaneous preterm birth. Pregnant women presenting for antenatal care <20 weeks gestation with singleton pregnancies are eligible for inclusion. The intervention is a 6-day course of clotrimazole vaginal pessaries (100 mg) and the primary outcome is spontaneous preterm birth <37 weeks gestation.

The study protocol draws on the usual antenatal care schedule, has been pilot-tested and the intervention involves only a minor modification of current practice. Women who agree to participate will self-collect a vaginal swab and those who are culture positive for Candida will be randomised (central, telephone) to open-label treatment or usual care (screening result is not revealed, no treatment, routine antenatal care). Outcomes will be obtained from population databases.

A sample size of 3,208 women with Candida colonisation (1,604 per arm) is required to detect a 40% reduction in the spontaneous preterm birth rate among women with asymptomatic candidiasis from 5.0% in the control group to 3.0% in women treated with clotrimazole (significance 0.05, power 0.8). Analyses will be by intention to treat.

Discussion

For our hypothesis, a placebo-controlled trial had major disadvantages: a placebo arm would not represent current clinical practice; knowledge of vaginal colonisation with Candida may change participants' behaviour; and a placebo with an alcohol preservative may have an independent affect on vaginal flora. These disadvantages can be overcome by the PROBE study design.

This trial will provide definitive evidence on whether screening for and treating asymptomatic candidiasis in pregnancy significantly reduces the rate of spontaneous preterm birth. If it can be demonstrated that treating asymptomatic candidiasis reduces preterm births this will change current practice and would directly impact the management of every pregnant woman.

Trial registration

Australian New Zealand Clinical Trials Registry ACTRN12610000607077

Experimental medical mycological research in Latin America - a 2000-2009 overview

An overview of current trends in Latin American Experimental Medical Mycological research since the beginning of the 21(st) century is done (search from January 2000 to December 2009). Using the PubMed and LILACS databases, the authors have chosen publications on medically important fungi which, according to our opinion, are the most relevant because of their novelty, interest, and international impact, based on research made entirely in the Latin American region or as part of collaborative efforts with laboratories elsewhere. In this way, the following areas are discussed: 1) molecular identification of fungal pathogens; 2) molecular and clinical epidemiology on fungal pathogens of prevalence in the region; 3) cell biology; 4) transcriptome, genome, molecular taxonomy and phylogeny; 5) immunology; 6) vaccines; 7) new and experimental antifungals.

Comparison of LPS-stimulated release of cytokines in punch versus transwell tissue culture systems of human gestational membranes

BACKGROUND

Cytokine signaling within the amnionic, chorionic and decidual extraplacental gestational membranes plays an important role in membrane rupture and the timing of birth. The predominant in vitro explant culture system for evaluating cytokine induction in human gestational membranes has been the free-floating biopsy punch culture. Punch systems have been used to investigate the impact of various toxicants, pharmaceuticals and genetic variation on expression of pro-inflammatory cytokines. More recently, a dual compartment transwell culture system has been developed that more closely mimics the intrauterine compartment. The current study compares these two systems with respect to release of pro- and anti-inflammatory cytokines in response to lipopolysaccharide (LPS), a model stimulant.

METHODS

Tissue samples were exposed to 100 ng/ml LPS for 12 h and cytokines were measured by ELISA. Data are expressed as increase relative to non-treated controls.

RESULTS

Levels of interleukin-6 increased in punch culture medium samples to a significantly greater extent (34.2 fold) compared with medium from transwell cultures in the amnion (6.6 fold) or choriodecidual (7.1 fold) compartments. Interleukin-8 also showed a significantly greater induction in punch (4.8 fold) than transwell amnion (1.6 fold) or choriodecidual (1.7 fold) samples. The anti-inflammatory interleukin-10 showed a significant difference between punch (36.5 fold) and transwell amnion (15.4 fold) samples, but no difference was observed between punch and transwell choriodecidual (28.5 fold) samples. Neither interleukin-1beta nor tumor necrosis factor-alpha (TNF-alpha) showed a significant difference between the punch and transwell samples.

CONCLUSIONS

These results indicate that the pattern of LPS-stimulated cytokine release from gestational membranes in vitro depends on the culture system used, confounding comparisons of studies that use different gestational membrane culture systems to study inflammatory responses.

Interaction between pathogenic bacteria and intrauterine leukocytes triggers alternative molecular signaling cascades leading to labor in women

Increased risk of preterm labor has been linked to cervicovaginal infection with Ureaplasma urealyticum and group B streptococci. Although various experimental models have been developed to study the role of amniochorion infection in preterm labor, they typically exclude the initial interaction between intrauterine leukocytes (recruited from decidual vessels into the avascular fetal membranes) and infecting bacteria. In this work, we ascertained whether inflammatory molecules secreted by bacterium-activated intrauterine leukocytes stimulate the amniochorion production of mediators involved in human labor. Using a two-step process beginning with placental circulating leukocytes as a proxy for intrauterine leukocytes, we found that coincubation of amniochorion explants with plasma from placental whole blood preincubated with group B streptococci resulted in a significant increase in tumor necrosis factor alpha (TNF-α) and matrix metalloproteinase 9 (MMP-9) levels in tissue. Extensive changes in the connective tissue arrangement and a decrease in collagen content demonstrated the degradation of the extracellular matrix following this treatment. In contrast, plasma from blood preconditioned with U. urealyticum induced a highly significant secretion of interleukin-1β (IL-1β) and prostaglandin E(2) (PGE(2)) by the amniochorion without changes in the extracellular matrix organization or content. These data demonstrate that group B streptococci induce degradation of the amniochorion as a result of MMP-9 production, probably via TNF-α, whereas U. urealyticum stimulates the secretion of PGE(2), probably via IL-1β, potentially stimulating myometrial contraction. Our study provides novel evidence that the immunological cells circulating within the uterine microenvironment respond differentially to an infectious agent, triggering alternative molecular signaling pathways leading to human labor.

Tissue-specific cytokine release from human extra-placental membranes stimulated by lipopolysaccharide in a two-compartment tissue culture system

BACKGROUND

The extra-placental gestational membranes secrete cytokines in response to bacteria and other infectious agents, with potentially adverse consequences for pregnancy. The present study used lipopolysaccharide (LPS) as a prototype endotoxin to investigate the pattern of stimulated cytokine release from the amniotic and choriodecidual sides of full-thickness human gestational membranes in a two-compartment tissue culture system.

METHODS

Gestational membranes were collected from healthy non-laboring caesarean deliveries at term. Full-thickness membranes from each placenta were cut into pieces, mounted on Transwell frames, and placed in culture wells to create a two-compartment culture with the gestational membranes serving as the barrier between compartments. The LPS (100 ng/ml) was added to the amniotic, choriodecidual or both chambers of the culture, and cytokines were assayed in the medium of the amniotic and choriodecidual chambers after 8 h of LPS exposure. Cytokine concentrations were analyzed by two-way analysis of variance for effects of treatment and side specificity of cytokine release from the membranes.

RESULTS

LPS exposure on the choriodecidual side of the membranes significantly increased TNF-alpha, IL-6, IL-10 and IL-8 in the choriodecidual compartment, whereas TNF-alpha was the only cytokine observed to increase in the amniotic compartment. When LPS treatment was to the amniotic side of the membranes, there were significant increases in TNF-alpha and IL-6 in the amniotic compartment as well as increased concentrations of TNF-alpha, IL-6 and IL-8 in the choriodecidual compartment; however, there were no statistically significant differences for IL-10 in either compartment. No statistically significant differences were observed for IL-1beta, TGF-beta or IL-4 concentrations in response to LPS, regardless of the exposure modality.

CONCLUSION

The amnion and choriodecidua exhibited distinct patterns of response to LPS with evidence of inflammatory signaling across the layers of the gestational membranes. These results suggest a complicated network of signaling within the gestational membranes, in which cytokine- and tissue-specific responses to inflammatory stimulation may have important implications for maintaining pregnancy in the challenge of microbial invasion of the uterine compartment.

In vitro secretion profiles of interleukin (IL)-1beta, IL-6, IL-8, IL-10, and TNF alpha after selective infection with Escherichia coli in human fetal membranes

BACKGROUND

Chorioamniotic membranes infection is a pathologic condition in which an abnormal secretion of proinflammatory cytokines halts fetal immune tolerance. The aim of the present study was to evaluate the functional response of human chorioamniotic membranes, as well as the individual contribution of the amnion and choriodecidua after stimulation with Escherichia coli, a pathogen associated with preterm labor.

METHODS

Explants of chorioamniotic membranes from 10 women (37-40 weeks of gestation) were mounted and cultured in a Transwell system, which allowed us to test the amnion and choriodecidua compartments independently. Escherichia coli (1 x 10 6 CFU/mL) was added to either the amniotic or the choriodecidual regions or both; after a 24-h incubation, the secretion of IL-1beta, IL-6, TNFalpha, IL-8, and IL-10 in both compartments was measured using a specific ELISA. Data were analyzed by Kruskal-Wallis one-way analysis of variance.

RESULTS

After stimulation with Escherichia coli, the choriodecidua compartment showed an increase in the secretion of IL-1beta (21-fold), IL-6 (2-fold), IL-8 (6-fold), and IL-10 (37-fold), regardless of which side of the membrane was stimulated; TNFalpha secretion augmented (22-fold) also but only when the stimulus was applied simultaneously to both sides. When the amnion was stimulated directly, the level of IL-1beta (13-fold) rose significantly; however, the increase in IL-8 secretion was larger (20-fold), regardless of the primary site of infection. TNFalpha secretion in the amnion compartment rose markedly only when Escherichia coli was simultaneously applied to both sides.

CONCLUSION

Selective stimulation of fetal membranes with Escherichia coli results in a differential production of IL-1beta, IL-6, TNFalpha, IL-8, and IL-10. These tissues were less responsive when the amnion side was stimulated. This is in agreement with the hypothesis that the choriodecidua may play a primary role during an ascending intrauterine infection, being the main barrier to progression of the infection into the amniotic cavity. Therefore, the tissue-specific capacities for the secretion of these immune modulators could be a determining factor for the degree of severity of the inflammation process in fetal membranes.