Transfer of cytokines through human fetal membranes

Leveraging bioengineering to assess cellular functions and communication within human fetal membranes

The fetal membranes enclose the growing fetus and amniotic fluid. Preterm prelabor rupture of fetal membranes is a leading cause of preterm birth. Fetal membranes are composed of many different cell types, both structural and immune. These cells must coordinate functions for tensile strength and membrane integrity to contain the growing fetus and amniotic fluid. They must also balance immune responses to pathogens with maintaining maternal-fetal tolerance. Perturbation of this equilibrium can lead to preterm premature rupture of membranes without labor. In this review, we describe the formation of the fetal membranes to orient the reader, discuss some of the common forms of communication between the cell types of the fetal membranes, and delve into the methods used to tease apart this paracrine signaling within the membranes, including emerging technologies such as organ-on-chip models of membrane immunobiology.

Canonical TGF-β signaling regulates the relationship between prenatal maternal depression and amygdala development in early life

Canonical transforming growth factor-beta (TGF-β) signaling exerts neuroprotection and influences memory formation and synaptic plasticity. It has been considered as a new target for the prevention and treatment of depression. This study aimed to examine its modulatory role in linking prenatal maternal depressive symptoms and the amygdala volumes from birth to 6 years of age. We included mother-child dyads (birth: n = 161; 4.5 years: n = 131; 6 years: n = 162) and acquired structural brain images of children at these three time points. Perinatal maternal depressive symptoms were assessed using the Edinburgh Postnatal Depression Scale (EPDS) questionnaire to mothers at 26 weeks of pregnancy and 3 months postpartum. Our findings showed that the genetic variants of TGF-β type I transmembrane receptor (TGF-βRI) modulated the association between prenatal maternal depressive symptoms and the amygdala volume consistently from birth to 6 years of age despite a trend of significance at 4.5 years of age. Children with a lower gene expression score (GES) of TGF-βRI exhibited larger amygdala volumes in relation to greater prenatal maternal depressive symptoms. Moreover, children with a lower GES of the TGF-β type II transmembrane receptor (TGF-βRII), Smad4, and Smad7 showed larger amygdala volumes at 6 years of age in relation to greater prenatal maternal depressive symptoms. These findings support the involvement of the canonical TGF-β signaling pathway in the brain development of children in the context of in utero maternal environment. Such involvement is age-dependent.

Partner social support during pregnancy and the postpartum period and inflammation in 3-month-old infants

Prenatal social stress "programs" offspring immune activity in animal models, but how the prenatal social environment affects human offspring inflammation is not known. Here, we test associations between prenatal partner support quality, i.e. positive/helpful support, negative/upsetting support, and their interaction, and infant inflammatory markers. A sample of 113 women from the Alberta Pregnancy Outcomes and Nutrition (APrON) cohort were followed from early pregnancy to 3-months postpartum. Partner support quality was measured during pregnancy and the postpartum period. Three-month-old infant blood samples were assayed for inflammatory markers, i.e., adaptive immune markers IFNγ, IL12p70 and IL10. The prenatal positive-by-negative partner support interaction predicted infant IFNγ, IL12p70, and IL10, p's<.035, independent of covariates and postpartum partner support. When negative partner support was high, high positive support predicted higher infant IFNγ, IL12p70, and IL10. As such, partner support during pregnancy that is both highly negative/upsetting and also highly positive/helpful predicted adaptive immunity markers in infants at 3 months of age.

Role of NF-κB/GATA3 in the inhibition of lysyl oxidase by IL-1β in human amnion fibroblasts

Preterm premature rupture of membranes (pPROMs) account for one-third of preterm births, a leading cause of neonatal death. Understanding the mechanism of membrane rupture is thus of clinical significance in the prevention of preterm birth. Parturition at both term and preterm is associated with increased abundance of proinflammatory cytokines in the fetal membranes regardless of the presence of infection, which is believed to induce rupture of membranes through activation of the matrix metalloproteinases. It remains unknown whether there are any alternative mechanisms underpinning proinflammatory cytokine-induced rupture of membranes. Here we showed that there were reciprocal increases in interleukin-1β (IL-1β) and decreases in lysyl oxidase (LOX), a collagen crosslinking enzyme, in the human amnion tissue following spontaneous rupture of membrane at term and pPROM. Studies using human amnion tissue explants revealed that IL-1β inhibited the expression of LOX, which can be reproduced in cultured human amnion fibroblasts. Mechanistic study revealed that IL-1β inhibited LOX expression through activation of p38 and Erk1/2 mitogen-activated protein kinase pathways, which resulted in the phosphorylation of the nuclear factor kappa light-chain enhancer of activated B (NF-κB) cell subunit p65 as well as GATA binding protein 3 (GATA3). Subsequently, activated NF-κB interacted with GATA3 at the NF-κB binding site of LOX promoter to inhibit its expression. Conclusively, this study has revealed an alternative mechanism that IL-1β may contribute to the rupture of membranes by attenuating collagen crosslinking through downregulation of LOX expression in amnion fibroblasts.

Prenatal maternal immune activation and brain development with relevance to psychiatric disorders

Growing evidence from epidemiological studies strongly suggests maternal infection as a risk factor for psychiatric disorders including bipolar disorder, schizophrenia, and autism. Animal studies support this association and demonstrate that maternal immune activation (MIA) changes brain morphology and inflammatory cytokines in the adult offspring. Evidence for changes in inflammatory cytokines is also demonstrated in human post-mortem brain and peripheral blood studies from subjects with psychiatric disorders. This perspective briefly highlights convincing evidence from epidemiological, preclinical and human pathological studies to support the role of MIA in major psychiatric disorders. A better understanding of the link between MIA and brain development in psychiatric disorders will lead to the development of novel immunomodulatory interventions for individuals at risk for psychiatric disorders.

Leptin, IL-6 and TNF-α levels in umbilical cord blood of healthy term newborns in relation to mode of delivery

In the development of the foetal immune system, cytokines play an important role in its function. Therefore, we sought to determine whether the mode of delivery affects the expression of leptin, IL-6 and TNF-α in umbilical cord blood in healthy term newborns. We collected 125 samples of umbilical cord blood to analyse leptin, IL-6 y TNF-α levels with multiplex immunoassay (MIA). The samples were classified according to mode of delivery: vaginal delivery (VD) and caesarean section (CS). Leptin and IL-6 had higher concentrations in umbilical cord blood in VD than in CS: 42.55 ng/ml (11.92-104.28) versus 35.20 ng/ml (3.26-9326.76), p  =  0.039; 9.32 pg/ml (1.13-2020.31) versus 3.81 pg/ml (0.52-834.69) p < 0.001, respectively. Also, a weak correlation between TNF-α and IL-6 was found (r = 0.238, p = 0.007). The most important finding in our study was the differential concentrations of leptin and IL-6 according to mode of delivery.

Do all roads lead to Rome? The role of neuro-immune interactions before birth in the programming of offspring obesity

The functions of the nervous system can be powerfully modulated by the immune system. Although traditionally considered to be quite separate, neuro-immune interactions are increasingly recognized as critical for both normal and pathological nervous system function in the adult. However, a growing body of information supports a critical role for neuro-immune interactions before birth, particularly in the prenatal programming of later-life neurobehavioral disease risk. This review will focus on maternal obesity, as it represents an environment of pathological immune system function during pregnancy that elevates offspring neurobehavioral disease risk. We will first delineate the normal role of the immune system during pregnancy, including the role of the placenta as both a barrier and relayer of inflammatory information between the maternal and fetal environments. This will be followed by the current exciting findings of how immuno-modulatory molecules may elevate offspring risk of neurobehavioral disease by altering brain development and, consequently, later life function. Finally, by drawing parallels with pregnancy complications other than obesity, we will suggest that aberrant immune activation, irrespective of its origin, may lead to neuro-immune interactions that otherwise would not exist in the developing brain. These interactions could conceivably derail normal brain development and/or later life function, and thereby elevate risk for obesity and other neurobehavioral disorders later in the offspring's life.

Diet, behavior and immunity across the lifespan

It is increasingly appreciated that perinatal events can set an organism on a life-long trajectory for either health or disease, resilience or risk. One early life variable that has proven critical for optimal development is the nutritional environment in which the organism develops. Extensive research has documented the effects of both undernutrition and overnutrition, with strong links evident for an increased risk for obesity and metabolic disorders, as well as adverse mental health outcomes. Recent work has highlighted a critical role of the immune system, in linking diet with long term health and behavioral outcomes. The present review will summarize the recent literature regarding the interactions of diet, immunity, and behavior.

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.

An experimental mixed bacterial infection induced differential secretion of proinflammatory cytokines (IL-1β, TNFα) and proMMP-9 in human fetal membranes

Overall, 1-4% of all births in the US are complicated by choriamnionitis. Choriamnionitis is a polymicrobial infection most often due to ascending genital microbes which, in over 65% of positive amniotic fluid cultures, involves two or more organisms. In this study, we determine the cytokines expression (IL-1β, TNFα) and prometalloproteinase activation (proMMP-2 and proMMP-9) after double o single infection an in vitro model of human fetal membranes. Fetal membranes at term were mounted in the Transwell culture system and after 24 h of infection, choriodecidual, and amnion media was collected. IL-1β and TNFα were evaluated by ELISA, whereas proMMP-9 and proMMP-2 were determined by substrate gel zymography. The choriodecidual and amnion compartments actively respond to the infectious process, which induced the secretion of IL-1β, TNFα, and proMMP-9 after either mixed or single infection. The proMMP-2 secretion profile was the same after all experimental conditions. There was no synergy between Streptococcus agalactiae and Escherichia coli for inducing the secretion of inflammatory factors or degradative metalloproteinase. In conclusion, these two bacteria could initiate different pathways to induce chorioamnioitis.

Choriodecidual group B streptococcal inoculation induces fetal lung injury without intra-amniotic infection and preterm labor in Macaca nemestrina

BACKGROUND

Early events leading to intrauterine infection and fetal lung injury remain poorly defined, but may hold the key to preventing neonatal and adult chronic lung disease. Our objective was to establish a nonhuman primate model of an early stage of chorioamnionitis in order to determine the time course and mechanisms of fetal lung injury in utero.

METHODOLOGY/PRINCIPAL FINDINGS

Ten chronically catheterized pregnant monkeys (Macaca nemestrina) at 118-125 days gestation (term=172 days) received one of two treatments: 1) choriodecidual and intra-amniotic saline (n=5), or 2) choriodecidual inoculation of Group B Streptococcus (GBS) 1×10(6) colony forming units (n=5). Cesarean section was performed regardless of labor 4 days after GBS or 7 days after saline infusion to collect fetal and placental tissues. Only two GBS animals developed early labor with no cervical change in the remaining animals. Despite uterine quiescence in most cases, blinded review found histopathological evidence of fetal lung injury in four GBS animals characterized by intra-alveolar neutrophils and interstitial thickening, which was absent in controls. Significant elevations of cytokines in amniotic fluid (TNF-α, IL-8, IL-1β, IL-6) and fetal plasma (IL-8) were detected in GBS animals and correlated with lung injury (p<0.05). Lung injury was not directly caused by GBS, because GBS was undetectable in amniotic fluid (~10 samples tested/animal), maternal and fetal blood by culture and polymerase chain reaction. In only two cases was GBS cultured from the inoculation site in low numbers. Chorioamnionitis occurred in two GBS animals with lung injury, but two others with lung injury had normal placental histology.

CONCLUSIONS/SIGNIFICANCE

A transient choriodecidual infection can induce cytokine production, which is associated with fetal lung injury without overt infection of amniotic fluid, chorioamnionitis or preterm labor. Fetal lung injury may, thus, occur silently without symptoms and before the onset of the fetal systemic inflammatory response syndrome.

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.

Tissue-specific human beta-defensins (HBD)1, HBD2, and HBD3 secretion from human extra-placental membranes stimulated with Escherichia coli

BACKGROUND

During an ascending infection along the reproductive tract, the extra-placental membranes must act as a selective and competent barrier against pathogens. Human beta defensins (HBD)1, HBD2, and HBD3 are key elements of innate immunity that are secreted to neutralize/control the progression of infection.

METHODS

Full-thickness membranes were mounted on a Transwell device, constituted by two independent chambers, 1 × 10(6) CFU/ml of Escherichia coli were added to either the amnion (AMN) or the choriodecidual (CHD) face or to both. Secretion profiles of HBD1, HBD2, and HBD3 to the culture medium were quantified by ELISA.

RESULTS

In comparison with basal conditions, the secretion profile of HBD1 remained without significant changes; HBD2 level in CHD and AMN increased 1.9- and 1.4-times, respectively, after stimulation with bacteria. HBD3 secretion level increased significantly (7.8 +/- 1.9 pg/micrograms) in the CHD but only if the stimulus was applied on the AMN side.

CONCLUSIONS

Selective stimulation of extra-placental membranes with E. coli, results in a tissue specific secretion of HBD1, HBD2, and HBD3 mainly in the CHD, which is the first infected region during an ascending infection.

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.

A safe vaccine (DV-STM-07) against Salmonella infection prevents abortion and confers protective immunity to the pregnant and new born mice

Pregnancy is a transient immuno-compromised condition which has evolved to avoid the immune rejection of the fetus by the maternal immune system. The altered immune response of the pregnant female leads to increased susceptibility to invading pathogens, resulting in abortion and congenital defects of the fetus and a subnormal response to vaccination. Active vaccination during pregnancy may lead to abortion induced by heightened cell mediated immune response. In this study, we have administered the highly attenuated vaccine strain ΔpmrG-HM-D (DV-STM-07) in female mice before the onset of pregnancy and followed the immune reaction against challenge with virulent S. Typhimurium in pregnant mice. Here we demonstrate that DV-STM-07 vaccine gives protection against Salmonella in pregnant mice and also prevents Salmonella induced abortion. This protection is conferred by directing the immune response towards Th2 activation and Th1 suppression. The low Th1 response prevents abortion. The use of live attenuated vaccine just before pregnancy carries the risk of transmission to the fetus. We have shown that this vaccine is safe as the vaccine strain is quickly eliminated from the mother and is not transmitted to the fetus. This vaccine also confers immunity to the new born mice of vaccinated mothers. Since there is no evidence of the vaccine candidate reaching the new born mice, we hypothesize that it may be due to trans-colostral transfer of protective anti-Salmonella antibodies. These results suggest that our vaccine DV-STM-07 can be very useful in preventing abortion in the pregnant individuals and confer immunity to the new born. Since there are no such vaccine candidates which can be given to the new born and to the pregnant women, this vaccine holds a very bright future to combat Salmonella induced pregnancy loss.

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.

Prevention of inflammatory activation of human gestational membranes in an ex vivo model using a pharmacological NF-kappaB inhibitor

Intrauterine inflammation plays a major role in the etiology of preterm labor and birth. We established an ex vivo model employing perfused full-thickness term gestational membranes to study membrane transport, function, and inflammatory responses. Exposure of the maternal (decidual) face of the membranes to LPS (5 microg/ml) resulted in increased accumulation of proinflammatory cytokines in the maternal compartment within 4 h, followed by a response in the fetal (amniotic) compartment. Using cytokine arrays, exposure to LPS was found to result in increased secretion of a large number of cytokines and chemokines in both compartments, most notably IL-5, IL-6, IL-7, MDC (macrophage-derived chemokine), MIG (monokine induced by IFN-gamma), TARC (thymus and activation-regulated chemokine), TGF-beta, and TNF-alpha. PGE(2) accumulation also increased in response to LPS, particularly in the fetal compartment. Cotreatment with sulfasalazine, which inhibited nuclear translocation of NF-kappaB p65, had a rapid and marked inhibitory effect on the rate of cytokine accumulation in the maternal compartment, with lesser but significant effects observed in the fetal compartment. While membrane integrity was not discernibly impaired with LPS or sulfasalazine exposure, rates of chorionic apoptosis after 20 h were doubled in sulfasalazine-treated tissues. We conclude that the system described provides a means of accurately modeling human gestational membrane functions and inflammatory activation ex vivo. Decidual LPS exposure was shown to elicit a robust inflammatory response in both the maternal and fetal compartments. Sulfasalazine was an effective antiinflammatory agent in this model, but also exerted proapoptotic effects that raise concerns regarding its placental effects when administered in pregnancy.

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.

Regulation of maternal serum and amniotic fluid cytokine profiles in the mouse: Possible roles in the onset of labour

Murine pregnancy is characterised by marked increases in serum cytokine profiles with advancing gestation, but whether these changes reflect concentrations in amniotic fluid is unknown. This study therefore profiled 23 cytokines by fluid-phase multiplex immunoassay of amniotic fluid and serum collected from naturally mated mice during mid- and late pregnancy (days 11 and 18, respectively). The marked increase in serum profile of many cytokines from days 11 to 18 was not reflected in amniotic fluid, wherein most cytokine concentrations were lower on day 18. Serum and amniotic fluid cytokine concentrations were largely inversely related, indicating separate, localised regulatory mechanisms geared towards the maintenance of pregnancy, modulation of immune effector cell function and optimisation of fetal development. We suggest that, while maternal systemic inflammatory priming prepares the mother for birth, the amniotic compartment exhibits a tightly regulated inflammatory quiescence. These findings are discussed in relation to the onset of labour, which ultimately results in the elevated cytokine amniotic levels traditionally associated with the final stages of pregnancy.

Interleukin-6 in the maternal circulation reaches the rat fetus in mid-gestation

Maternal systemic infection during pregnancy may expose the fetus to infectious agents and high levels of mediators of the resulting inflammatory response, such as IL-6 (IL-6). Increased fetal and maternal levels of IL-6 have been associated with adverse neonatal outcome but might also stress the fetus and contribute to cardiovascular and neuroendocrine dysfunction in adulthood. It is unclear whether interleukins cross the placental barrier, although this matter has been little studied. The aim of this study was therefore to investigate if IL-6 administered to pregnant rats in vivo is transferred to the fetus. We injected 125I IL-6 i.v. to pregnant dams at gestation day 11-13 (mid-gestation) or 17-19 (late gestation). We found 125I-IL-6 in the exposed fetuses as well as in amniotic fluids. Fetal 125I-IL-6 levels were markedly higher in animals injected in mid-gestation compared with late pregnancy (p < 0.01). This difference was mirrored in a 15-fold higher unidirectional materno-fetal clearance for 125I-IL-6 in mid-gestation (p < 0.01). We conclude that the permeability of the rat placental barrier to IL-6 is much higher in mid-gestation than in late pregnancy. Maternally derived IL-6 may directly induce fetal injury but also stimulate the release of fetal stress hormones resulting in stimuli or insults in neuroendocrine structures and hormonal axes which might lead to disease at adult age.

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

Ascendant colonization of pathogenic microorganisms from the vagina to the uterus is strongly associated to preterm labour and premature rupture of membranes. This study evaluated the secretion of interleukin (IL)-1beta, tumour necrosis factor (TNF)alpha, IL-6, prostaglandin E(2) (PGE(2)), and metalloproteinases 9 and 2 by the human chorioamnion stimulated with Candida albicans. Chorioamniotic membranes were obtained after delivery by elective Cesarean section from women at 37-40 weeks of gestation without evidence of active labour. The membranes were mounted in Transwell devices that form two independent compartments, which allow testing the individual responses and contributions of the amnion and choriodecidua. One million CFU ml(-1) of C. albicans was added to either the amniotic or choriodecidual surface and secretions of the markers were measured in both compartments using specific enzyme-linked immunosorbent assay and zymography. Fetal membranes followed different secretion patterns of proinflammatory cytokines depending on the side to which the stimulus was applied. IL-1beta was produced in higher amounts in the presence of C. albicans when applied to the choriodecidual side; TNFalpha and IL-6 secretion did not change in either the amnion or choriodecidual region. PGE(2) synthesis depicted a different pattern, the amniotic tissue was more responsive than the choriodecidual tissue, and this response tended to be higher even when only the amniotic side was stimulated. Matrix metalloproteinases (MMP)-9 increased after stimulation, being the choriodecidua its main source. Selective stimulation with C. albicans induced a differential secretion of IL-1beta, PGE(2), and MMP-9, resulting from a cooperative and bidirectional communication between the amnion and the choriodecidua.

Interleukin-6 and interleukin-8 in cervical and amniotic fluid: relationship to microbial invasion of the chorioamniotic membranes

OBJECTIVE

To evaluate the levels of interleukin (IL)-6 and IL-8 in cervical and amniotic fluid in relation to the presence of bacteria in the membranes in women in preterm labour (PTL).

DESIGN

A prospective follow up study.

SETTING

Sahlgrenska University Hospital, Göteborg, Sweden. Sample Women with singleton pregnancies (<34 weeks) presenting with PTL (n = 30).

METHODS

Amniotic fluid was retrieved transabdominally and cervical fluid was sampled from the uterine cervix at admission and analysed for IL-6 and IL-8 with enzyme-linked immunosorbent assay (ELISA). At birth, the chorioamniotic membranes were separated and samples for polymerase chain reaction (PCR) for Ureaplasma urealyticum and Mycoplasma hominis and general culture were obtained.

MAIN OUTCOME MEASURE

IL-6 and IL-8 in relation to microbial invasion of the chorioamniotic membranes.

RESULTS

Bacteria were found in the membranes in 8 of 21 patients in PTL for whom chorioamnion as well as amniotic fluid PCR and cultures were available. Cervical IL-6 was associated with detectable bacteria in the chorioamniotic membranes in women in PTL (median 8.2 ng/mL vs 0.73 ng/mL; P = 0.01). The IL-6 (median 13 ng/mL vs 1.7 ng/mL; P = 0.004) and IL-8 (median 7.2 ng/mL vs 0.28 ng/mL; P = 0.01) levels in amniotic fluid were higher in PTL cases in which bacteria were found in the chorioamniotic membranes.

CONCLUSION

IL-6 in cervical fluid and IL-6 and IL-8 in amniotic fluid were higher in those PTL cases in which bacteria were found in the chorioamniotic membranes.

Fetal membrane inflammatory cytokines: a switching mechanism between the preterm premature rupture of the membranes and preterm labor pathways

Inflammatory cytokines are involved in both preterm labor and preterm premature of the membranes pathways; however, the interaction between TNF-alpha and its receptors may dictate the clinical outcome of pregnancy.

Periodontitis, a marker of risk in pregnancy for preterm birth

BACKGROUND

Why chronic periodontitis may induce an inflammatory response with premature pregnancy termination is unclear.

AIMS

(1) To assess if periodontitis predicts premature gestation; (2) to study amniotic fluid cytokines and periodontitis variables in early-stage pregnancy.

MATERIAL AND METHODS

A periodontal examination and collection of amniotic fluid was performed (weeks 15-20) of pregnancy in 36 women at risk for pregnancy complications. Amniotic fluid (bacteria), vaginal smears and intra-oral plaque samples were studied. Cytokine levels in amniotic fluid were studied in relation to other study variables.

RESULTS

Periodontitis was diagnosed in 20% of normal and in 83% of preterm birth cases (p<0.01). Bacteria were never found in the amniotic fluids studied. Sub-gingival plaque samples including bacteria in the orange and red complexes were found in 18% of full-term 100% of preterm cases (p<0.001) and total colony-forming units (CFUs) were higher in preterm birth (p<0.01). Amniotic levels of interleukin (IL)-6 and prostaglandin-E2 (PGE2) were higher in preterm cases (p<0.001). Amniotic IL-6 (r=0.56, p<0.01) and PGE2 (r=0.50, p<0.01) cytokine levels were correlated with CFU from sub-gingival plaque samples (r2=0.44). The odds ratio of preterm delivery and having periodontitis was 20.0 (95% confidence interval (CI): 2.0-201.7, p<0.01). The odds of >60 CFU in sub-gingival plaque and preterm birth was 32.5:1 (95% CI: 3.0-335.1, p<01).

CONCLUSIONS

Pregnant women with findings of elevated amniotic fluid levels of PGE2, IL-6 and IL-8 in the 15-20 weeks of pregnancy and with periodontitis are at high risk for premature birth. The implication of this is that periodontitis can induce a primary host response in the chorioamnion leading to preterm birth.

Monocyte chemotactic protein-1 in cervical and amniotic fluid: relationship to microbial invasion of the amniotic cavity, intra-amniotic inflammation, and preterm delivery

OBJECTIVE

The purpose of this study was to evaluate the role of monocyte chemotactic protein-1 in cervical and amniotic fluid in women in preterm labor and with preterm premature rupture of membranes.

STUDY DESIGN

Women with singleton pregnancies (<or=34 weeks) in preterm labor (n=75 women), with preterm premature rupture of membranes (n=47 women), and at term (n=45 women) who were undergoing elective cesarean delivery were included. Cervical and amniotic fluid were sampled.

RESULTS

Monocyte chemotactic protein-1 in cervical and amniotic fluid was higher in women in preterm labor than in women at term. Cervical monocyte chemotactic protein-1 in women in preterm labor was associated with microbial invasion of the amniotic cavity, intra-amniotic inflammation, delivery within 7 days, and at <or=34 weeks. Amniotic monocyte chemotactic protein-1 correlated to microbial invasion of the amniotic cavity in women with preterm premature rupture of membranes, intra-amniotic inflammation in preterm labor, preterm premature rupture of membranes, delivery within 7 days, and delivery at <or=34 weeks in women in preterm labor.

CONCLUSION

Monocyte chemotactic protein-1 in cervical and amniotic fluid levels are elevated in preterm labor and preterm premature rupture of membranes and correlate to intra-amniotic infection/inflammation.

Dexamethasone or interleukin-10 blocks interleukin-1beta-induced uterine contractions in pregnant rhesus monkeys

OBJECTIVE

The purpose of this study was to determine whether treatment with the immune modulators dexamethasone or interleukin-10 prevents interleukin-1beta-induced uterine contractions in a nonhuman primate model.

STUDY DESIGN

Thirteen chronically instrumented rhesus monkeys at 135 +/- 1 days of gestation (term, 167 days) received one of three interventions: (1) intra-amniotic interleukin-1beta (10 microg) infusion with maternal dexamethasone (1 mg/kg) intravenously every 6 hours for 1 day before interleukin-1beta and for 2 days thereafter (n = 4), (2) intra-amniotic interleukin-1beta infusion with maternal interleukin-10 (25 microg/kg) given intravenously and 100 microg interleukin-10 given intra-amniotically before the interleukin-1beta and continued every 8 hours for 3 days (n = 5), and (3) intra-amniotic interleukin-1beta administered alone (n = 5). Uterine activity was monitored continuously and quantified as the hourly contraction area (millimeters of mercury times seconds per hour) in all groups until delivery. Amniotic fluid was sampled for leukocyte counts and assayed for prostaglandins E(2) and F(2)alpha, cytokines interleukin-1beta, interleukin-6, interleukin-8, tumor necrosis factor-alpha, interleukin-10, and interleukin-1 receptor antagonist by specific assays. Maternal and fetal blood were assayed for cortisol, dehydroepiandrosterone sulfate, and estradiol.

RESULTS

Interleukin-1beta infusion in the absence of immune modulators resulted in an increase in uterine activity and amniotic fluid proinflammatory cytokines, prostaglandins, and leukocytes. Dexamethasone and interleukin-10 treatment significantly reduced interleukin-1beta-induced uterine contractility (P <.05) and amniotic fluid prostaglandins (P <.05) but not interleukin-8 or interleukin-1 receptor antagonist. Amniotic fluid interleukin-6 and maternal and fetal cortisol, dehydroepiandrosterone sulfate, and estradiol concentrations were reduced by dexamethasone (P <.05), whereas tumor necrosis factor-alpha levels and leukocyte counts were attenuated by interleukin-10 treatment (P <.05). An inverse relationship was noted between amniotic fluid interleukin-10 concentrations and interleukin-1beta-induced uterine activity (r = -0.74, P <.05).

CONCLUSION

Dexamethasone and interleukin-10 exert similar inhibitory effects on interleukin-1beta-induced uterine activity, which appears to be mediated by a decrease in prostaglandin production. Reduced estrogen biosynthesis or suppression of tumor necrosis factor-alpha and leukocyte migration may contribute to the tocolytic actions of dexamethasone and interleukin-10, respectively. Dexamethasone and interleukin-10 are likely to be useful adjuncts in the treatment of preterm labor that is associated with inflammation or infection.

Prenatal exposure to maternal infection alters cytokine expression in the placenta, amniotic fluid, and fetal brain

Prenatal exposure to infection appears to increase the risk of schizophrenia and other neurodevelopmental disorders. We have hypothesized that cytokines, generated in response to maternal infection, play a key mechanistic role in this association. E16 timed pregnancy rats were injected i.p. with Escherichia coli lipopolysaccharide (LPS) to model prenatal exposure to infection. Placenta, amniotic fluid and fetal brains were collected 2 and 8h after LPS exposure. There was a significant treatment effect of low-dose (0.5mg/kg) LPS on placenta cytokine levels, with significant increases of interleukin (IL)-1beta (P<0.0001), IL-6 (P<0.0001), and tumor necrosis factor-alpha (TNF-alpha) (P=0.0001) over the 2 and 8h time course. In amniotic fluid, there was a significant effect of treatment on IL-6 levels (P=0.0006). Two hours after maternal administration of high-dose (2.5mg/kg) LPS, there were significant elevations of placenta IL-6 (P<0.0001), TNF-alpha (P<0.0001), a significant increase of TNF-alpha in amniotic fluid (P=0.008), and a small but significant decrease in TNF-alpha (P=0.035) in fetal brain. Maternal exposure to infection alters pro-inflammatory cytokine levels in the fetal environment, which may have a significant impact on the developing brain.

Indomethacin blocks interleukin 1beta-induced myometrial contractions in pregnant rhesus monkeys

OBJECTIVE

We sought to determine whether blockade of prostaglandin synthesis with indomethacin prevents interleukin 1beta-induced increases in uterine contractions in a nonhuman primate model.

STUDY DESIGN

Maternal and fetal vascular catheters, intra-amniotic fluid pressure catheters, and fetal electrocardiographic and myometrial electromyographic electrodes were implanted in 11 rhesus monkeys at 124 +/- 2 days' gestation (term, 167 days). After postsurgical stabilization (136 +/- 2 days) indomethacin 50 mg was administered orally twice daily for 5 days (n = 6). On day 3 human recombinant interleukin 1beta 10 microg was infused into the amniotic cavity over 2 hours. Five days after the last indomethacin dose the study was repeated without indomethacin treatment. Uterine activity was continuously monitored and quantified as the hourly contraction area (millimeters of mercury. seconds per hour) in the experimental group and a control group (n = 5) that received interleukin 1beta alone. At timed intervals amniotic fluid was sampled for leukocyte counts and assayed for prostaglandin E(2) and F(2alpha), the inflammatory cytokines interleukin 1beta, interleukin 6, interleukin 8, tumor necrosis factor alpha, and interleukin 1 receptor antagonist by specific assays.

RESULTS

Uterine activity was increased severalfold from baseline after interleukin 1beta infusion alone and in the absence of indomethacin treatment (P <.05). There was no increase in uterine contractility when interleukin 1beta was infused concurrently with indomethacin treatment. Concentrations of amniotic fluid leukocytes and cytokines increased significantly after interleukin 1beta infusion in both the presence and absence of indomethacin. Amniotic fluid prostaglandins E(2) and F(2alpha) were suppressed during indomethacin treatment but rose significantly after interleukin 1beta infusion in the absence of indomethacin. Except for higher interleukin 6, cytokine levels were unaltered by indomethacin.

CONCLUSIONS

After interleukin 1beta infusion, indomethacin blocked the development of uterine activity. Amniotic fluid prostaglandins were suppressed by indomethacin treatment, but cytokines and leukocytes were not. These results suggest that prostaglandins or possibly other indomethacin-suppressible compounds stimulate uterine activity after interleukin 1beta infusion in late-gestation rhesus monkeys or that indomethacin has direct tocolytic effects.

The production of interleukin-1beta from human fetal membranes is not obligatory for increased prostaglandin output

Bacterial endotoxin increased the expression of mRNA (maximal after 4 hr) for interleukin-1beta (IL-1beta) and the release of mature protein from intact human fetal membranes. In contrast, the change in expression of mRNA for type 2 cyclo-oxygenase (COX-2) was biphasic, with peaks after 0.5-1 hr and after 8 hr of culture. An antibody to IL-1beta was without effect after 4 hr of culture, inhibited endotoxin-stimulated prostaglandin E2 (PGE2) production after 8 hr of culture, and caused a parallel decrease in the expression of mRNA for COX-2. We conclude that endotoxin induced the expression of COX-2 through IL-1beta-independent and IL-1beta-dependent mechanisms, and these differences are time dependent. Corticotrophin-releasing hormone (CRH) or platelet-activating factor (PAF) also increased the expression of mRNA for IL-1beta and the release of IL-1beta from some, but not all, fetal membranes. The antibody to IL-1beta did not affect CRH-stimulated or PAF-stimulated PGE2 production or COX-2 expression. We conclude that CRH and PAF can induce the expression of IL-1beta, but this is not obligatory for increased PGE2 release, and the effect of these stimuli on COX-2 expression is a direct, IL-1beta-independent effect.

Changes in the expression of the type-2 but not the type-1 cyclo-oxygenase enzyme in chorion-decidua with the onset of labour

OBJECTIVE

To determine the relative expression of cyclo-oxygenase (COX)-1 and COX-2 in the chorion-decidual part of human fetal membranes following delivery at term and to identify any changes in expression associated with labour.

METHODS

Fetal membranes were collected from 12 term pregnancies before labour following elective caesarean section and from 12 spontaneous vaginal deliveries. Expression of COX-1 and COX-2 mRNA was measured using a previously validated quantitative RT-PCR assay.

RESULTS

COX-2 expression exceeded that of COX-1 by approximately eight-fold. COX-1 expression did not change but COX-2 expression was found to increase four-fold with labour.

CONCLUSIONS

Chorion-decidua has the capacity to contribute to the increase in prostaglandin synthesis within the uterus associated with labour. As in the amnion, it is COX-2 and not COX-1 which is upregulated with labour. COX-2 selective anti-prostaglandins should therefore be as effective as nonselective drugs in inhibition of fetal membrane prostaglandin synthesis.

Permeability of human placenta and fetal membranes to thyrotropin-stimulating hormone in vitro

We determined the placental transfer of TSH in an in vitro model of dually perfused isolated lobule in 28 human term placentas by adding varying concentrations (5-60 microIU mL(-1)) of TSH as a single bolus dose to the closed maternal circulation. Transmembrane transfer of TSH was also studied by adding 45 microIU mL(-1) to the maternal or fetal compartment of a dual chamber of fetal membranes in culture. Passage of freely diffusible markers creatinine and antipyrine were also studied in this model. TSH concentration was measured by third generation chemiluminescence assay with a sensitivity of 10 mIU mL(-1). In the perfusion experiments, at physiologic concentrations the slow decline of TSH in the maternal circulation was associated with a small linear increase in fetal levels to 0.11 +/- 0.04% of initial dose at 2 h. The placental transfer rate was 0.08 microIU min(-1). Increasing maternal concentrations of TSH were associated with proportional increases in transfer rate (y = 0.002x; R2 = 0.99) and placental uptake (y = 0.01x; R2 = 0.97). The placental permeability of TSH was 2.4 x 10(-4) mL min(-1) g(-1) and was proportional to its coefficients of diffusion in water and molecular size. The transmembrane transfer and permeability of TSH was comparable to those of the placenta. We conclude that TSH crosses the human term placenta and fetal membranes sparingly.

Stimulation of prostaglandin production from intact human fetal membranes by bacteria and bacterial products

The addition of live or sonicated Escherichia coli, or endotoxin from E. coli increased the release of prostaglandins (PG) on both sides of intact human fetal membranes after 24 h of incubation, indicating that live bacteria were not required to activate prostaglandin production. Time-course studies showed that the levels of PGE2 and PGF2alpha on the fetal side of the membrane were increased 6 h after the addition of endotoxin, whereas levels on the maternal side increased within 1-2 h. These changes were independent of the side to which the endotoxin was added, indicating that a stimulatory factor passes through the fetal membranes. This factor is not endotoxin, which did not cross the membranes, and further studies are required to identify this endogenous stimulus. Prostaglandin metabolite levels were either unaffected or increased by endotoxin, indicating that the main effect is at the level of increased prostaglandin biosynthesis rather than decreased metabolism.

The role of amniotic fluid L-selectin, GRO-alpha, and interleukin-8 in the pathogenesis of intraamniotic infection

OBJECTIVE

Our purpose was to compare and correlate amniotic fluid GRO-alpha, interleukin-8, and L-selectin in patients with and without intraamniotic infection.

STUDY DESIGN

Amniocentesis was performed on 45 pregnant women with preterm contractions, labor, or rupture of membranes. Fourteen patients had intraamniotic infection, and 31 did not. Intraamniotic infection was defined as the presence of a positive amniotic fluid culture. Amniotic fluid tests for Gram stain, glucose, neutrophil counts, creatinine, pH, and specific gravity were performed. Amniotic fluid levels of soluble L-selectin, interleukin-8, and GRO-alpha were measured by an enzyme-linked immunoassay and normalized by amniotic fluid creatinine levels. The Mann-Whitney Utest and Spearman's rank correlation test were used for statistical analyses.

RESULTS

Amniotic fluid median levels of soluble L-selectin, interleukin-8, and GRO-alpha were significantly higher in pregnant women with intraamniotic infection than in those without intraamniotic infection (soluble L-selectin: median 3334.6 ng/mg creatinine, range 408.4 to 15,956.8 vs 717.2 ng/mg creatinine, range 129.4 to 4601.9, p = 0.009; GRO-alpha: median 841.6 ng/mg creatinine, range 28.1 to 8591.7 vs 56.8 ng/mg creatinine, range 0.0 to 440.2, p < 0.0001; interleukin-8: median 4932.7 ng/mg creatinine, range 0.0 to 55,058.7 vs 28.3 ng/mg creatinine, range 0.0 to 1161.6, p = 0.0004). Patients with intraamniotic infection had significantly higher amniotic fluid leukocyte counts and leukocyte esterase activities and significantly lower amniotic fluid glucose concentrations compared with those without intraamniotic infection. Amniotic fluid GRO-alpha, interleukin-8, and soluble L-selectin were positively correlated, and each was positively correlated with amniotic fluid leukocytes and negatively correlated with amniotic fluid levels of glucose.

CONCLUSIONS

Our data indicate amniotic fluid GRO-alpha and interleukin-8 may be two potent leukocyte chemoattractants and activators, and L-selectin is rapidly shed from leukocytes in the amniotic fluid in patients with intraamniotic infection.

Inflammatory cytokines in newborn infants

Serum levels of IL-1beta, IL-6 and TNF-alpha were measured in 48 healthy, termed neonates on the 1st (N1), 5th (N5) and 40th (N40) day after birth, compared with those in maternal serum (MS), umbilical cord (UC) and adult controls. Cytokine values in N1 and N5 were significantly elevated, than those in UC and in controls (P<0.0001). IL-1beta and IL-6 declined significantly from N1 to N40 (P<0.0001), while TNF-alpha increased significantly from N1 to N5 and declined thereafter. MS infinity IL-1beta and IL-6, but not MS infinity TNF-alpha, were significantly higher than those of controls (P<0.0001). IL-1beta values depended on the mode of delivery. In conclusion, the increased concentrations of IL-1beta, IL-6 and TNF-alpha during the perinatal period might suggest their involvement in an inflammation-like process during normal parturition, and reflect also a newborn immune response to the stress of delivery and environmental changes.

The interleukin-1 system in gestational tissues at term: effect of labour

Previous studies suggest that the interleukin-1 (IL-1) system is involved in preterm labour, at least in cases associated with intrauterine infection. To investigate the effect of term labour without infection on the IL-1 system, the messenger ribonucleic acid (mRNA) expression of IL-1 beta, IL-1 receptor type I (IL-1R tI), IL-1 receptor antagonist (IL-1ra), and IL-1 beta converting enzyme (ICE) were examined by Northern blot analysis and by reverse transcriptase-polymerase chain reaction (RT-PCR) in paired samples of decidua and placenta obtained from women having spontaneous vaginal delivery (group 1) or elective caesarean section (group 2) at term. In addition, concentrations of IL-1 beta and IL-1ra proteins were measured by ELISA in paired decidual and placental cytosols. In all decidual samples, IL-1 beta mRNA was expressed strongly, and the IL-1 beta concentration was 40- to 50-fold higher than in paired placental samples, in which the signal for IL-1 beta mRNA could be detected by RT-PCR only, and the amount of IL-1 beta protein was undetectable or very low. A comparison between the study groups revealed that the decidual IL-1 beta mRNA level tended to be higher in group 1, and the median IL-1 beta concentration in decidual cytosols was significantly higher in group 1 than in group 2 (P < 0.05). The IL-1R tI mRNA transcript was stronger in decidual than in paired placental samples in both groups. The mRNAs encoding ICE and IL-1ra were detected by RT-PCR in decidual and placental samples from both groups. The IL-1ra concentration tended to be higher in decidual cytosols than in paired placental cytosols, but there was no difference between the study groups. The IL-1ra/IL-1 beta ratio was significantly lower in decidual samples in women with spontaneous labour than in women without labour (P < 0.05). The results of this study confirm that decidua is the major site of IL-1 beta production and action in term gestational tissues. Furthermore, the results show that the major change in decidual/placental IL-1 system during parturition is the increase in decidual IL-1 beta production. Whether the increased IL-1 beta production precedes or is a consequence of labour, remains still unclear.

The molecular mechanisms of term and preterm labor: recent progress and clinical implications

Current tocolytic protocols rely largely on the use of beta-mimetics to induce myometrial quiescence and delay delivery. Unfortunately, the rapid transplacental passage and poor receptor specificity of the commonly used beta-mimetics results in widespread activation of intrauterine and extrauterine beta 1 and beta 2 receptors. The use of beta-mimetics is associated with a range of well-recognized and potentially dangerous side effects for mother and fetus. The value of continued use of beta-agonists after obtaining uterine quiescence also has been the subject of recent debate. In this article we have attempted to explore the biochemical and molecular rationale for the use of alternative therapeutic modalities in the treatment and prevention of PTL. In the light of the current view that the term "preterm labor" covers a considerable diversity of causes, we propose that a range of treatment regimes should be chosen on the basis of the diagnosis and classification of the patient according to the their particular condition. Although the measurement of several biochemical parameters have been suggested to be of use in predicting PTL, we believe that a panel of diagnostic indicators (e.g., free or total CRH, IL-6, extracellular matrix proteases, fetal fibronectin) is more likely to provide useful diagnostic information on which appropriate treatment modalities can be selected (Table 1). Because of the complex and interactive nature of the mechanisms operating within the intrauterine environment to regulate myometrial activation and uterotonin production, we speculate that a combination of tocolytics, anti-inflammatory agents, uterotonic antagonists, and receptor blockers is likely to be more effective than a monotherapeutic approach, which focuses on only one facet of the process of uterine activation for pharmacologic intervention. For example, the use of antibiotics, PGHS inhibitors, and/or beta-mimetics might be an appropriate first line of treatment for infection-associated PTL in extreme prematurity. If it is successful, this treatment might be followed by longer term use of a progestagen and/or NO donor to maintain myometrial quiescence until closer to term. Alternatively, use of progesterone or oxytocin antagonists may be effective in augmenting the actions of beta-mimetics while reducing their side effects, whereas other combinations may be useful as long-term prophylactics in women with a high risk of developing PTL. Improvements continue in our diagnostic ability to correctly identify the different causes of preterm labor. We anticipate that careful selection of differing combinations of therapeutic options will result in significant reductions in the morbidity, mortality, and healthcare costs associated with preterm birth.

Interleukin-1 beta intra-amniotic infusion induces tumor necrosis factor-alpha, prostaglandin production, and preterm contractions in pregnant rhesus monkeys

OBJECTIVE

To describe the temporal and quantitative consequences of intra-amniotic interleukin-1 beta infusion in a nonhuman primate model.

METHODS

On days 128-138 of gestation (term 167 days), four chronically instrumented rhesus monkeys (Macaca mulatta) underwent serial intra-amniotic infusions of 2, 5, and 10-20 micrograms recombinant human interleukin-1 beta. Each infusion was for 2 hours, and subsequent infusions were at least 48 hours later. Amniotic fluid was sampled serially both before and after infusion for interleukin-1 beta, tumor necrosis factor-alpha (TFN-alpha), and prostaglandin (PG) E2 and F2 alpha by specific assays, and uterine activity in each monkey was recorded continuously.

RESULTS

Intra-amniotic concentrations of interleukin-1 beta rose dramatically after infusion. This rise was rapidly followed by the appearance of TNF-alpha in the amniotic cavities of all animals, with maximal levels reached 5 hours after the initiation of the infusion. Both interleukin-1 beta and TNF-alpha were rapidly cleared from the amniotic fluid and returned to baseline levels by 24-48 hours. Increases in PGE2 and F2 alpha paralleled those of the two cytokines but remained elevated for the duration of the experiments. The stimulation of uterine contractility from a pre-infusion level of 200 mmHg. seconds/hour to 6000 mmHg. seconds/hour occurred an average of 6-10 hours after interleukin-1 beta infusion. These stimulations were transient, usually abating by 22 hours after infusion, and did not result in frank labor.

CONCLUSION

In the rhesus monkey, intra-amniotic infusion of interleukin-1 beta rapidly induces production of intra-amniotic TNF-alpha as well as PGE2 and F2 alpha, followed by uterine contractility. Uterine activity diminishes as cytokine levels return to pre-infusion levels, even in the presence of elevated intraamniotic PG levels. Tumor necrosis factor-alpha may act synergistically with interleukin-1 beta in the pathophysiology of cytokine-related preterm labor.

Immunmodulating cytokines induce term and preterm parturition

The aim of our study was to investigate if cytokines, which are able to cause preterm delivery is case of intraamniotic infection, also participate in the mechanisms of normal term labor. Therefore we estimated cytokine concentrations in cercicovaginal secretions of 96 patients, divided into four different collectives. In collective A (women with spontaneous term labor) cytokine concentrations raised from a median level of 278 pg/ml for Il-1 beta and 263 pg/ml for Il-6 in early term labor to a median level of 3351 pg/ml for Il-1 beta and 39,442 pg/ml for Il-6 at complete cervical dilatation. TNF-alpha-exclusively appeared after spontaneous rupture of fetal membranes. In collective B and C (women with preterm rupture of fetal membranes) cytokine concentrations declined from a maximum level of 1425 pg/ml for TNF-alpha, 12,982 pg/ml for Il-1 beta and 29,727 pg/ml for Il-6 soon after preterm rupture of membranes to a minimum level of 93 pg/ml for TNF-alpha, 851 pg/ml for Il-1 beta and 780 pg/ml for Il-6 with remission of labor in case of successful tocolytic treatment. High concentrations reappeared with the onset of labor, unresponsive to tocolysis. In collective D (women with intact membranes) TNF-alpha was not detectable and Il-1 beta and II-6 appeared exclusively in the presence of labor. Our results suggest, that normal term labor may be controlled by biochemical processes, similar to infection-associated signal transduction, which is commonly accepted to induce preterm labor.