Interleukin-8 release from human gestational tissue explants: effects of gestation, labor, and chorioamnionitis

Group B streptococcus induces cellular senescence in human amnion epithelial cells through a partial interleukin-1-mediated mechanism

Group B streptococcus (GBS) infection is a significant public health concern associated with adverse pregnancy complications and increased neonatal mortality and morbidity. However, the mechanisms underlying the impact of GBS on the fetal membrane, the first line of defense against pathogens, are not fully understood. Here, we propose that GBS induces senescence and inflammatory factors (IL-6 and IL-8) in the fetal membrane through interleukin-1 (IL-1). Utilizing the existing transcriptomic data on GBS-exposed human fetal membrane, we showed that GBS affects senescence-related pathways and genes. Next, we treated primary amnion epithelial cells with conditioned medium from the choriodecidual layer of human fetal membrane exposed to GBS (GBS collected choriodecidual [CD] conditioned medium) in the absence or presence of an IL-1 receptor antagonist (IL-1Ra). GBS CD conditioned medium significantly increased β-galactosidase activity, IL-6 and IL-8 release from the amnion epithelial cells. Cotreatment with IL1Ra reduced GBS-induced β-galactosidase activity and IL-6 and IL-8 secretion. Direct treatment with IL-1α or IL-1β confirmed the role of IL-1 signaling in the regulation of senescence in the fetal membrane. We further showed that GBS CD conditioned medium and IL-1 decreased cell proliferation in amnion epithelial cells. In summary, for the first time, we demonstrate GBS-induced senescence in the fetal membrane and present evidence of IL-1 pathway signaling between the choriodecidua and amnion layer of fetal membrane in a paracrine manner. Further studies will be warranted to understand the pathogenesis of adverse pregnancy outcomes associated with GBS infection and develop therapeutic interventions to mitigate these complications.

Effects of recombinant bovine interleukin-8 (rbIL-8) treatment on health, metabolism, and lactation performance in Holstein cattle I: Production and functional characterization of rbIL-8 in vitro and in vivo

In the present study, we standardized processes of cloning and purification of recombinant bovine interleukin-8 (rbIL-8) from bacterial culture and assessed its biological activity in Holstein cattle. Plasmid containing a subclone of bovine IL-8 was expressed using Escherichia coli BL21 and cell lysate was purified by chromatography. The presence of rbIL-8 was assessed by Western blot analyses and function was confirmed in vitro using a chemotaxis chamber. Based on optical density values, chemoattractant properties of rbIL-8 were 10-fold greater compared with control wells. Two in vivo studies were conducted to assess the biological activity of rbIL8. For study 1, one-year-old Holstein heifers (n = 20) were randomly allocated to receive a single intravaginal administration containing 1,125 µg of rbIL-8 diluted in 20 mL of saline solution (rbIL-8, n = 10) or a single intravaginal administration of 20 mL of saline solution (control, n = 10). For study 2, nonpregnant lactating Holstein cows (n = 31) were randomly allocated to receive an intrauterine administration with 1,125 µg of rbIL-8 diluted in 20 mL of saline solution (rbIL-8, n = 11), a positive control consisting of resin-purified lysate of E. coli BL21 not transfected with the plasmid coding for rbIL-8 diluted in 20 mL of saline solution (E. coli, n = 10), and a negative control administered with 20 mL of saline solution (control, n = 10). An increase in vaginal neutrophils was observed in heifers treated with rbIL-8 within 3 h of treatment, but not in control heifers. Additionally, intrauterine administration of rbIL-8 increased the proportion of PMN cells in uterine cytological samples from 3.5% before treatment to 75.8% 24 h later-an increase that was not observed in the negative control group and cows treated with resin-purified lysate of E. coli. To further evaluate the effect of local and systemic rbIL-8 stimulation on the dynamics of circulating white blood cells, a third study was conducted. In study 3, nonpregnant 8-mo-old Holstein heifers (n = 30) were randomly allocated into 1 of 3 treatment groups: intravenous rbIL-8 (1,125 µg of rbIL-8 diluted in 5 mL of saline solution, n = 10); intravaginal rbIL-8 (1,125 µg of rbIL-8 diluted in 20 mL of saline solution; n = 10); or intravaginal saline (20 mL of saline solution, n = 10). Intravenous injection of rbIL-8 resulted in a transient increase in rectal temperature, which was greater at 2 h after treatment compared with cows treated intravaginally with rbIL-8 or heifers treated with saline solution. Heifers treated with rbIL-8 intravenously displayed a marked reduction in neutrophils, basophils, lymphocytes, and monocytes within the first 4 h posttreatment compared with heifers treated intravaginally. However, at 6 h after treatment, heifers treated with rbIL-8 intravenously displayed a rebound in white blood cell counts caused by an increase in neutrophil counts. These results show that the presented purification method is effective and results in biologically active rbIL-8 that can be used safely to modulate immune responses in cattle.

Changes of leukocyte counts and expression of pro- and anti-inflammatory cytokines in peripheral leukocytes in periparturient dairy cows with retained fetal membranes

In dairy cows, retained fetal membranes (RFM) affect reproductive performance. The aim of this study was to examine the leukocyte counts and the gene expression of tumour necrosis factor α (TNFα), interleukin 1β (IL-1β), IL-8, and IL-10 in polymorphonuclear leukocytes (PMNs) and peripheral blood mononuclear cells (PBMCs) in cows with (n = 5) or without (n = 5) RFM during the peripartum period. The lymphocyte counts in RFM cows were higher than those in control cows throughout the experiment (p < .05). The expression of IL-8 in PMNs of control cows was higher (p < .05) compared with that of RFM cows postpartum. In cows with RFM, IL-1β expression was higher (p < .05) in PMNs at 6 weeks postpartum whereas the expression of IL-1β was lower (p < .05) in PBMCs at 4 weeks postpartum. The expression of IL-10 in PBMCs of control cows was higher (p < .05) than that of RFM cows at 2 weeks prepartum and 4 weeks postpartum. Taken together, our data indicate that changes of gene expression of pro- and anti-inflammatory cytokines in RFM cows might be associated with the delayed placental separation and development of uterine inflammation in RFM cows.

Chemokine (C-C motif) ligand 25 expressed by trophoblast cells and leukocytes bearing its receptor Ccr9: An alliance during embryo implantation?

PROBLEM

We hypothesized that trophoblast expression of Ccl25 attracts a specific leukocyte cell population to the implantation site for local regulation.

METHOD OF STUDY

Mice blastocysts, ectoplacental cones, and decidua at gestational days 3.5-7.5 were evaluated for Ccl25 and Ccr9 expressions. Peripheral availability and characterization of Ccr9+ leukocytes were determined by flow cytometry. Leukocyte chemotaxis was assessed in the presence of Ccl25 recombinant protein and embryos using antisense oligomers (ODNs) to Ccl25 and Ccr9 neutralizing antibody.

RESULTS

Ccl25 was expressed by embryonic cells, whereas Ccr9 expression was strong at the maternal compartment and in PBMC. Immunolocalization confirmed this expression. In vitro, chemotaxis assays showed that the embryonic Ccl25 signals to Ccr9+ PBMCs. Maternal Ccr9+α4β7+ monocytes switch from an anti-inflammatory phenotype (F4/80+11b+Ly6C-TGF-β+ cells, pre-implantation) to an inflammatory profile (F4/80+11b+Ly6C+TNF-α+ cells, post-implantation).

CONCLUSION

Our data support the establishment of a CCL25/CCR9-axis at the maternal-fetal interface in mice, which may be involved in immune regulatory mechanisms during embryo implantation.

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

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

Evidence of perturbations of the cytokine network in preterm labor

OBJECTIVE

Intraamniotic inflammation/infection is the only mechanism of disease with persuasive evidence of causality for spontaneous preterm labor/delivery. Previous studies about the behavior of cytokines in preterm labor have been largely based on the analysis of the behavior of each protein independently. Emerging evidence indicates that the study of biologic networks can provide insight into the pathobiology of disease and improve biomarker discovery. The goal of this study was to characterize the inflammatory-related protein network in the amniotic fluid of patients with preterm labor.

STUDY DESIGN

A retrospective cohort study was conducted that included women with singleton pregnancies who had spontaneous preterm labor and intact membranes (n = 135). These patients were classified according to the results of amniotic fluid culture, broad-range polymerase chain reaction coupled with electrospray ionization mass spectrometry, and amniotic fluid concentration of interleukin (IL)-6 into the following groups: (1) those without intraamniotic inflammation (n = 85), (2) those with microbial-associated intraamniotic inflammation (n = 15), and (3) those with intraamniotic inflammation without detectable bacteria (n = 35). Amniotic fluid concentrations of 33 inflammatory-related proteins were determined with the use of a multiplex bead array assay.

RESULTS

Patients with preterm labor and intact membranes who had microbial-associated intraamniotic inflammation had a higher amniotic fluid inflammatory-related protein concentration correlation than those without intraamniotic inflammation (113 perturbed correlations). IL-1β, IL-6, macrophage inflammatory protein (MIP)-1α, and IL-1α were the most connected nodes (highest degree) in this differential correlation network (degrees of 20, 16, 12, and 12, respectively). Patients with sterile intraamniotic inflammation had correlation patterns of inflammatory-related proteins, both increased and decreased, when compared to those without intraamniotic inflammation (50 perturbed correlations). IL-1α, MIP-1α, and IL-1β were the most connected nodes in this differential correlation network (degrees of 12, 10, and 7, respectively). There were more coordinated inflammatory-related protein concentrations in the amniotic fluid of women with microbial-associated intraamniotic inflammation than in those with sterile intraamniotic inflammation (60 perturbed correlations), with IL-4 and IL-33 having the largest number of perturbed correlations (degrees of 15 and 13, respectively).

CONCLUSIONS

We report for the first time an analysis of the inflammatory-related protein network in spontaneous preterm labor. Patients with preterm labor and microbial-associated intraamniotic inflammation had more coordinated amniotic fluid inflammatory-related proteins than either those with sterile intraamniotic inflammation or those without intraamniotic inflammation. The correlations were also stronger in patients with sterile intraamniotic inflammation than in those without intraamniotic inflammation. The findings herein could be of value in the development of biomarkers of preterm labor.

Chemotactic activity of gestational tissues through late pregnancy, term labor, and RU486-induced preterm labor in Guinea pigs

PROBLEM

Is increased leukocyte chemotactic activity (CA) from gestational tissues necessary for term or preterm labor in guinea pigs?

METHOD OF STUDY

Tissue extracts were prepared from pregnant guinea pig decidua-myometrium, cervix, fetal membranes (amniochorion), and placenta during early third trimester (n = 8), term not in labor (TNL, n = 5), and term spontaneous labor (TL, n = 6), RU486-induced preterm labor (PTL, n = 6), or controls (cPTL, n = 5). Leukocyte CA was assessed using a modified Boyden chamber assay. Extract chemokine and maternal progesterone concentrations were quantified by enzyme immunoassay.

RESULTS

Only the extracts from amniochorion demonstrated increased CA through late gestation and labor. In contrast, CA was decreased in extracts from amniochorion and cervix from animals after RU486-induced PTL. Maternal progesterone concentrations remained high in all groups.

CONCLUSION

Leukocyte CA of intrauterine tissues is increased in term spontaneous labor. However, RU486-induced preterm labor occurs in the absence of increased CA.

Short and inflamed cervix predicts spontaneous preterm birth (COLIBRI study)

OBJECTIVE

To develop a new strategy of predicting spontaneous preterm birth (sPTB) by combination of transvaginal ultrasound (TVUS) assessment and inflammatory proteins detection in vaginal secretions.

METHODS

Prospective study of 87 women referred for cervical length assessment with a standardized TVUS combined to vaginal secretions sampling. Samples were analyzed for presence of 10 cytokines. Main outcome was sPTB (<37 weeks of gestation). Associations were assessed with the chi-square, Fisher's exact test (p < 0.05) and Wald's logistic regression.

RESULTS

sPTB occurred in 25.3% of women at a median gestational age of 35.6 weeks of gestation. Short cervix (<25 mm) (n = 24) was associated with sPTB (p < 0.01) as interleukine (IL)-1β, IL-8 and IL-10 in vaginal secretions (p < 0.05). In multivariate analysis, short cervix and IL-8 in vaginal secretions were independently associated with sPTB (OR 3.58 (95%CI 1.02; 12.61) and 14.55 (95%CI 1.64; 128.83), respectively) as their combination (OR 4.33 (95%CI 1.25; 14.95)). By categorizing cervical length by presence of IL-8, sPTB occurred in 55.6% of women with a short inflamed cervix.

CONCLUSION

COLIBRI study used a novel, single-step method of vaginal secretions sampling during TVUS and demonstrated that combination of short cervix and IL-8 in vaginal secretions is a promising sPTB predictive test.

Soluble ST2, a modulator of the inflammatory response, in preterm and term labor

OBJECTIVE

Intra-amniotic infection/inflammation (IAI) is causally linked with spontaneous preterm labor and delivery. The ST2L receptor and its soluble form (sST2) are capable of binding to interleukin (IL)-33, a member of the IL-1 superfamily. Members of this cytokine family have been implicated in the onset of spontaneous preterm labor in the context of infection. Soluble ST2 has anti-inflammatory properties, and plasma concentrations are elevated in systemic inflammation, such as sepsis, acute pyelonephritis in pregnancy and the fetal inflammatory response syndrome. The aims of this study were to examine: (1) whether amniotic fluid concentrations of sST2 change with IAI, preterm, and term parturition; and (2) if mRNA expression of ST2 in the chorioamniotic membranes changes with acute histologic chorioamnionitis in women who deliver preterm.

METHOD

A cross-sectional study was conducted to determine amniotic fluid concentrations of sST2 in: (1) women with preterm labor (PTL) who delivered at term (n=49); (2) women with PTL who delivered preterm without IAI (n=21); (3) women with PTL who delivered preterm with IAI (n=31); (4) term pregnancies not in labor (n=13); and (5) term pregnancies in labor (n=43). The amniotic fluid concentration of sST2 was determined by ELISA. The mRNA expression of ST2 in the chorioamniotic membranes of women who delivered preterm with (n=24), and without acute histologic chorioamnionitis (n=19) was determined by qRT-PCR.

RESULTS

(1) Patients with PTL who delivered preterm with IAI had a lower median amniotic fluid concentration of sST2 compared to those with PTL who delivered preterm without IAI [median 410 ng/mL, inter-quartile range (IQR) 152-699 ng/mL versus median 825 ng/mL, IQR 493-1216 ng/mL; p=0.0003] and those with PTL who delivered at term [median 410 ng/mL, IQR 152-699 ng/mL versus median 673 ng/mL, IQR 468-1045 ng/mL; p=0.0003]; (2) no significant differences in the median amniotic fluid concentration of sST2 were observed between patients with PTL who delivered at term and those who delivered preterm without IAI (p=0.4), and between women at term in labor and those at term not in labor (p=0.9); (3) the mean mRNA expression of ST2 was 4-fold lower in women who delivered preterm with acute histologic chorioamnionitis than in those without this lesion (p=0.008).

CONCLUSIONS

The median sST2 amniotic fluid concentration and mRNA expression of ST2 by chorioamniotic membranes is lower in PTL associated with IAI and acute histologic chorioamnionitis than in PTL without these conditions. Changes in the median amniotic fluid sST2 concentration are not observed in preterm and term parturition without IAI. Thus, amniotic fluid sST2 in the presence of IAI behaves differently when compared to sST2 in the plasma of individuals affected by fetal inflammatory response syndrome, acute pyelonephritis in pregnancy, and adult sepsis. Decreased concentrations of sST2 in IAI are likely to promote a pro-inflammatory response, which is important for parturition in the context of infection.

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.

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

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

An introduction to Toll-like receptors and their possible role in the initiation of labour

Toll-like receptors (TLR) have emerged as key upstream mediators of inflammation at many tissue sites in humans. Inflammatory processes are involved in the process of parturition suggesting that TLR activity within gestation-associated tissues might have an important role in the initiation and/or maintenance of normal term labour and in various pathological states of pregnancy such as infection-associated preterm labour. Either TLRs or their signalling molecules might be excellent therapeutic targets for prevention of preterm labour.

Maternal serum interleukin-1 beta, -6 and -8 levels and potential determinants in pregnancy and peripartum

AIMS

To measure maternal serum interleukins (IL) in pregnancy, delivery and early puerperium, and to identify their potential determinants.

METHODS

Prospective longitudinal measures of serum IL-1 beta, IL-6 and IL-8 in 38 healthy pregnant women at antenatal visits, through labor and delivery, with clinical correlates (infection, vaginal hemorrhage and anemia) recorded by questionnaire.

RESULTS

Pregnancy IL levels remained consistently low. IL-1 beta increased shortly before delivery, then returned to pregnant levels, except where blood loss exceeded 500 ml. IL-6 and IL-8 rose at labor onset and exceeded pregnancy levels through postpartum day three. Postpartum IL-6 was higher after non-elective cesarean section than after spontaneous delivery (P < 0.0001), and where blood loss exceeded 500 ml. IL-6 and IL-8 were higher with systemic infection during delivery (P < 0.0001) and on postpartum day one (P < 0.05); IL-8 was higher in anemia (delivery: P < 0.005; postpartum day 1: P < 0.05). Differences due to delivery mode and systemic infection remained significant after correction for other conditions.

CONCLUSIONS

Labor-dependent inflammation increases all IL levels at delivery. Further studies with larger sample sizes are required to establish reference values differentiating physiology from pathology as an aid to peripartum management.

Secretions of interleukin-1beta and tumor necrosis factor alpha by whole fetal membranes depend on initial interactions of amnion or choriodecidua with lipopolysaccharides or group B streptococci

The present study evaluated the secretions of interleukin (IL)-1beta and tumor necrosis factor (TNF) alpha by fetal membranes stimulated with group B streptococci (GBS) and lipopolysaccharide (LPS). The aim was to evaluate the initial response of full-thickness membranes to the microbial insult using an in vitro experimental model that allowed testing of the individual contributions of amnion and choriodecidua to stimulation. Full-thickness membranes were obtained after delivery by elective cesarean section from women at 37-40 wk of gestation without evidence of active labor. The membranes were mounted in Transwell devices, physically separating the upper and lower chambers. The LPS (500 ng/ml) or GBS (1 x 10(6) colony-forming units/ml) was added to either the amniotic or choriodecidual surface, and accumulation of IL-1beta and TNFalpha were measured in both compartments using a specific ELISA. Fetal membranes followed different patterns of secretion of proinflammatory cytokines that depended on the side to which the stimulus was added or the nature of the stimulus itself. The TNFalpha was secreted by amnion and choriodecidua in the presence of LPS or GBS, and stimulation with GBS induced a greater synthesis of IL-1beta than did stimulation with LPS. Choriodecidual tissue was more responsive than amniotic tissue, and this response tended to be higher even when the stimulation was only on the amniotic side. However, the amnion plays an active role in recognizing LPS or GBS, contributing a significant amount of TNFalpha. Thus, cooperative and bidirectional communications occur between amnion and choriodecidua in response to bacterial products, which include intermembranous cytokine traffic and signaling between tissues.

Pre-B-cell colony-enhancing factor, a novel cytokine of human fetal membranes

OBJECTIVE

Our purpose was to determine whether pre-B-cell colony-enhancing factor (PBEF) is expressed in the human fetal membranes during normal gestation and parturition in the absence of infection and to show its effects on the expression of interleukin (IL)-6 and IL-8.

STUDY DESIGN

PBEF was immunolocalized in the fetal membranes from early pregnancy, at preterm, and at term. Its expression was quantitated by Northern analysis in separated uninfected amnion, chorion, decidua, and placenta of patients at term before labor and in full-thickness membranes before and after spontaneous labor at preterm and at term. Amnion-like epithelial (WISH) cells and fetal membrane explants were treated with recombinant PBEF (rhPBEF), and the expression of IL-6 and IL-8 was quantitated.

RESULTS

PBEF was immunolocalized throughout gestation in the amniotic epithelium and mesenchymal cells as well as the chorionic cytotrophoblast and parietal decidua. Northern analysis showed significantly more (P <.01) PBEF expressed in the amnion than in either chorion or placenta. Its expression increased after labor at both preterm and term and correlated with that of IL-8 (r = 0.87). rhPBEF treatment of WISH cells significantly increased IL-6 (P <.05) and IL-8 (P <.01) gene expression after 4 hours and of IL-8 protein after 24 hours (P <.01); similar 4-hour treatment of fetal membrane explants significantly increased IL-6 (P <.01) and IL-8 (P <.05) gene expression.

CONCLUSION

PBEF is a novel cytokine constitutively expressed by the fetal membranes during pregnancy. It increased the expression of IL-6 and IL-8 and may be important in both normal spontaneous labor and infection-induced preterm labor.

Cytokines of the placenta and extra-placental membranes: biosynthesis, secretion and roles in establishment of pregnancy in women

Virtually all known cytokines have been demonstrated to be expressed in the placenta and associated fetal and maternal membranes during normal gestation. In addition to playing their traditional roles as modulators of immunological function, cytokines derived from the placenta and extraplacental membranes, together with other locally-derived growth factors, appear to be implicated in various aspects of implantation and placental development. Imbalances in the intrauterine cytokine milieu around the time of implantation and invasion may play a causative role in disorders associated with early pregnancy failure, and are also associated with the abnormal trophoblast development seen in gestational trophoblastic disease. Cytokines thus appear to be an important component of a paracrine/autocrine communication network operating within the feto-maternal interface to ensure the successful establishment of pregnancy.

Cytokines of the placenta and extra-placental membranes: roles and regulation during human pregnancy and parturition

Summary In an earlier, companion, review, we concluded that cytokines produced by the placenta and associated membranes are likely to be involved in control of the processes of implantation and placental development (Bowen et al., 2002). In this review, we discuss evidence that cytokines continue to be part of a paracrine/autocrine regulatory network in the placenta and membranes throughout the mid and late stages of gestation. Cytokines are involved in regulation of placental growth during these later stages of pregnancy and also function to protect the fetus from pathological organisms. The evidence, while not entirely consistent, suggests that production of certain cytokines within the extraplacental membranes is altered during normal term parturition, whereas in the villous placenta evidence of labour-associated changes is much more equivocal. Roles for cytokines have been postulated in many facets of parturition, including expulsion of the fetus by uterine contractions, membrane rupture, and dilation of the cervix. Imbalances and disruptions to the cytokine milieu have been implicated in a number of diseases of pregnancy involving abnormalities of both placental growth/establishment and initiation of parturition. Cytokine secretion induced by intrauterine infection is associated with increased occurrence or severity of some neonatal diseases. This wealth of data supports the view that cytokines are an integral part of a functional regulatory/communication network operating within the placental-maternal unit during normal gestation.

Uterine chemokines in reproductive physiology and pathology

PROBLEM

Chemokines are increasingly recognized as important regulators of uterine function.

METHODS OF STUDY

The following is a review of uterine chemokines, especially monocyte chemotactic protein (MCP)-1, interleukin (IL)-8, and regulated-upon-activation normal-T-cell-expressed and -secreted (RANTES) protein, in reproductive physiology and pathology.

RESULTS

It is increasingly clear that IL-8, MCP-1, RANTES and their receptors are produced by endometrial, myometrial, and trophoblast cell types in a timed and co-ordinated manner. In addition to the regulation of leukocyte migration and function, uterine chemokines also display specific roles in endometrial angiogenesis, apoptosis, proliferation, and differentiation. IL-8, MCP-1 and RANTES are regulated by local growth factors and cytokines such as tumor necrosis factor-alpha (TNF-alpha), interferon-gamma, and IL-1. IL-8 takes part in cervical ripening and parturition. IL-8, MCP-1 and RANTES are also found at high levels in the peritoneal fluid of women with endometriosis.

CONCLUSION

Co-ordination of chemokine-chemokine receptor interactions plays an important role in the menstrual cycle and successful pregnancy. Moreover, unbalanced chemokine expression contributes to pathologic conditions typified by uncontrolled cellular proliferation, migration and invasion.

Decreased neutrophil function as a cause of retained placenta in dairy cattle

It is unclear why some cows fail to expel the placenta following calving. One theory suggests the fetal placenta must be recognized as "foreign" tissue and rejected by the immune system after parturition to cause expulsion of the placenta. We hypothesized that impaired neutrophil function causes retained placenta (RP). We examined the ability of neutrophils to recognize fetal cotyledon tissue as assessed by a chemotaxis assay, which utilized a placental homogenate obtained from a spontaneously expelled placenta as the chemoattractant. Neutrophil killing ability was also estimated by determining myeloperoxidase activity in isolated neutrophils. Blood samples were obtained from 142 periparturient dairy cattle in two herds. Twenty cattle developed RP (14.1%). Neutrophils isolated from blood of cows with RP had significantly lower neutrophil function in both assays before calving, and this impaired function lasted for 1 to 2 wk after parturition. The addition of antibody directed against interleukin-8 (IL-8) to the cotyledon preparation used as a chemoattractant inhibited chemotaxis by 41%, suggesting that one of the chemoattractants present in the cotyledon at parturition is IL-8. At calving, plasma IL-8 concentration was lower in RP cows (51 +/- 12 pg/ml) than in cows expelling the placenta normally (134 +/- 11 pg/ml). From these data, we suggest that neutrophil function is a determining factor for the development of RP in dairy cattle. Also, depressed production of IL-8 may be a factor affecting neutrophil function in cows developing RP.

Immunolocalization of proinflammatory cytokines in myometrium, cervix, and fetal membranes during human parturition at term

Each of the proinflammatory cytokines interleukin (IL)-1beta, IL-6, IL-8, and tumor necrosis factor (TNF) alpha has been identified in reproductive tissues during labor. The cellular origin of these cytokines is unclear. The aim of this study was to localize these proinflammatory cytokines in myometrium (upper and lower segment), cervix, and fetal membranes at term. Biopsies were taken from women undergoing cesarean section either before or after the onset of labor. Immunohistochemistry was used to localize each of the cytokines IL-1beta, IL-6, IL-8, and TNFalpha. Leukocytes were localized using an antibody to CD45. In myometrium and cervix, immunostaining for IL-1beta was predominantly in leukocytes. In fetal membranes, IL-1beta localized to leukocytes and to the stromal cells of the decidua. In myometrium, IL-6, IL-8, and TNFalpha were restricted to leukocytes, which were present in greater numbers in tissue obtained during labor. In cervix, IL-6, IL-8, and TNFalpha localized to leukocytes and glandular and surface epithelium. IL-8 also localized to cervical stromal cells. In fetal membranes, IL-6 and TNFalpha were expressed by decidual stromal cells, infiltrating leukocytes, and extravillous trophoblasts. In membranes, IL-8 localized to leukocytes in the chorion but was not detected in the amnion. In fetal membranes collected at labor, IL-8 was expressed in decidual stromal cells. Infiltrating leukocytes are a major source of cytokines in uterine tissues during labor.

Myeloperoxidase-dependent generation of hypochlorite-modified proteins in human placental tissues during normal pregnancy

Myeloperoxidase (MPO), which is released from cytoplasmic granules of activated phagocytes by a degranulation process, reacts with H(2)O(2) (generated during the oxidative burst) and chloride ions to generate hypochlorous acid/hypochlorite (HOCl/OCl(-)). HOCl, a strong oxidant, in turn reacts with proteins to form HOCl-modified proteins. The presence of these cytotoxic chloramines during inflammatory conditions, eg, atherosclerosis and glomerular and tubulointerstitial injury, suggested that chloramines are powerful oxidants that can have profound biologic effects. In the present study, immunoreactive MPO was identified in fetal membranes and the basal plate and in maternal and fetal blood cells of human placental tissues. Monocytes/macrophages represent the major cell source for MPO in human placental tissues. Immunohistochemical findings revealed that HOCl-modified proteins are present in normal human term placenta but not during the first trimester of pregnancy (Weeks 7 to 12). HOCl-modified proteins were localized in areas formed by fetally derived cells as well as maternal decidual tissues, ie, areas where fetal extravillous trophoblast cells invade the maternal tissue and stimulate the maternal immune system. HOCl-modified proteins, products of the MPO-H(2)O(2)-chloride system in vivo, were not present intracellularly, but immunoreactivity for HOCl-modified proteins was cell-associated and/or present in the extracellular matrix. Extravillous trophoblast cells, which may also exert phagocytic activities, showed no intracellular immunoreactivity for MPO or HOCl-modified proteins. The present findings indicate that the generation of HOCl-modified proteins during normal pregnancy is a physiologic rather than a pathophysiologic process.

Il-1 beta, Il-6, Il-8 and G-CSF in the diagnosis of early-onset neonatal infections

OBJECTIVE

To determine whether inflammatory cytokine concentrations (Il-1 beta, Il-6, Il-8 and G-CSF) in umbilical cord blood are useful predictors of an early-onset neonatal infection.

MATERIAL AND METHODS

240 women and their newborns were enrolled in our study and umbilical cord blood samples collected from neonates (n = 240) were subjected to ELISA for Il-1 beta, Il-6, Il-8 and G-CSF. Clinical outcome of the neonates was followed and documented. Placenta histology was also available in majority of the cases (n = 195).

RESULTS

Early-onset neonatal infection was diagnosed in 5.4% of neonates (13/240) and placental examination showed histologic chorioamnionitis in 17.9% (35/195). Both Il-1 beta and Il-6 cord blood concentrations were elevated in association with histologic chorioamnionitis (Il-1 beta-2.7 vs. 2.1 pg/ml, p < 0.05 and Il-6 15.6 vs. 12.8 pg/ml, p < 0.005). Only Il-6 was elevated (16.0 vs. 13.2 pg/ml, p < 0.05) in neonates with early-onset bacterial infections. ROC analysis showed acceptable diagnostic performance of Il-6 in the identification of acute histologic chorioamnionitis and clinical neonatal infection.

CONCLUSION

Il-6 in umbilical cord blood seems to be a promising predictor for early-onset neonatal infections.

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 distribution of receptors for the pro-inflammatory cytokines interleukin (IL)-6 and IL-8 in the developing human fetus

Interleukin-6 receptor alpha (IL-6R) and interleukin-8 receptor (IL-8RB) are widely expressed in adult human and murine tissues. Little is known about the expression of these receptors and the function of their ligands in the developing human fetus.

OBJECTIVES

To determine the tissue distribution and cellular expression of IL-6R and IL-8RB in the developing human fetus.

METHODS

Reverse transcription-PCR and immunohistochemical staining were performed on brain, spinal cord, eye, heart, lung, liver, spleen, adrenal, kidney, intestine, and placenta from fetuses of 8 and 16+/-2 weeks post-conception.

RESULTS

IL-6R and IL-8RB mRNA were detected in all tissues tested at both time points. Immunoreactivity to anti-IL-6R antibody was present on neurons, and in neuropil of the brain, as well as in bone marrow, bronchi, hepatocytes, zona glomerulosa of the adrenal, glomerular cells in kidney, spleen, and placental trophoblasts. Cell-specific expression for IL-8RB in the central nervous system was localized to specific groups of neurons and astrocytes in the brain and spinal cord, including the neural retina. In somatic organs IL-8RB was detected in bone marrow, myocardiocytes, bronchiolar epithelial cells, hepatocytes, cells of the zona glomerulosa and the zona fasciculata of the adrenal, the collecting system of the kidney, enterocytes of the bowel and in placental cells.

CONCLUSION

The widespread expression of these cytokine receptors suggests a nonhematopoietic role for their ligand in the developing fetus.