Gestational age-dependent expression of IL-10 and its receptor in human placental tissues and isolated cytotrophoblasts

The anti-inflammatory limb of the immune response in preterm labor, intra-amniotic infection/inflammation, and spontaneous parturition at term: a role for interleukin-10

OBJECTIVE

The anti-inflammatory limb of the immune response is crucial for dampening inflammation. Spontaneous parturition at term and preterm labor (PTL) are mediated by inflammation in the cervix, membranes, and myometrium. This study focuses on the changes in the amniotic fluid concentrations of the anti-inflammatory cytokine interleukin (IL)- 10. The objectives of this study were to determine whether there is a relationship between amniotic fluid concentrations of IL-10 and gestational age, parturition (at term and preterm), and intra-amniotic infection/inflammation (IAI).

STUDY DESIGN

A cross-sectional study was conducted including 301 pregnant women in the following groups: (1) mid-trimester of pregnancy who delivered at term (n = 112); (2) mid-trimester who delivered preterm neonates (n = 30); (3) term not in labor without IAI (n = 40); (4) term in labor without IAI (n = 24); (5) term in labor with IAI (n = 20); (6) PTL without IAI who delivered at term (n = 31); (7) PTL without IAI who delivered preterm (n = 30); (8) PTL with IAI who delivered preterm (n = 14). IL-10 concentrations in amniotic fluid were determined by a specific and sensitive immunoassay. Non-parametric statistics were used for analysis.

RESULTS

(1) IL-10 was detectable in amniotic fluid and its median concentration did not change with gestational age from mid-trimester to term. (2) Patients in labor at term had a significantly higher median amniotic fluid IL-10 concentration than that of patients at term not in labor (p = 0.04). (3) Women at term in labor with IAI had a significantly higher median amniotic fluid IL-10 concentration than that of patients at term in labor without IAI (p = 0.02). (4) Women with PTL and IAI who delivered preterm had a significantly higher median amniotic fluid concentration of IL-10 than those without IAI who delivered preterm and than those who delivered at term (p = 0.009 and p < 0.001, respectively). (5) Among patients with preterm labor without IAI, those who delivered preterm had a significantly higher median amniotic fluid IL-10 concentration than those who delivered at term (p = 0.03).

CONCLUSIONS

The anti-inflammatory cytokine IL-10 is detectable in the amniotic fluid of normal pregnant women. Spontaneous parturition at term and in preterm gestation is associated with increased amniotic fluid concentrations of IL-10. IAI (preterm and at term) is also associated with increased amniotic fluid concentrations of IL-10. We propose that IL-10 has a role in the regulation of the immune response in vivo by initiating actions that dampen inflammation.

Cytokine gene polymorphisms in recurrent spontaneous abortions: a comprehensive review

PROBLEM

Cytokine gene polymorphism studies in women with recurrent spontaneous abortion (RSA) are reviewed to provide comprehensive understanding and a direction for the future investigation.

METHOD OF STUDY

A search of PubMed was made to identify the published data between 2001 and 2007 regarding RSA and cytokine gene polymorphisms.

RESULTS

Either allele and/or genotype frequencies of the following polymorphisms were reported to be significantly different between women with RSA and controls: IFN-gamma +874A-->T, TA (P = 0.01), AA (P = 0.04); IL-6, -634C-->G CG/GG (P = 0.026); IL-10, -592C-->A CC (P = 0.016); IL-1B -511C (P = 0.035), -31T (P = 0.029); IL-1RA, IL1RN*2 (P = 0.002), and IL1RN*3 (P = 0.002). None of these studies was repeatedly reported by others to be significantly different. Among these, four cytokine polymorphisms (IFN-gamma, +874A-->T; IL-1B -511C; IL-1RA, IL1RN*2, IL1RN*3) were refuted by others and rest of them were studied once.

CONCLUSION

Multiple cytokine polymorphisms were reported to be associated with RSA. However, a majority of studies were not confirmed by other investigators or refuted by others. Inconsistent study results might be related to: (i) the production of these cytokines is partly under genetic controls and other factors affect cytokine levels; (ii) ethnic background, environmental factors, and selection criteria for study populations are different and (iii) the possibilities exist that multiple cytokine gene polymorphisms or other genes in linkage disequilibrium may play a role in RSA.

Deviations in populations of peripheral blood mononuclear cells and endometrial macrophages in the cow during pregnancy

The presence of conceptus alloantigens necessitates changes in maternal immune function. Here, we used the cow to evaluate whether species with epitheliochorial placentation have changes in specific leukocyte populations during pregnancy similar to those reported in species with hemotropic placentae. At days 33–34 of pregnancy, there was no effect of pregnancy status on the number of cells positive for CD8, CD4, γδT cell receptor, or the monocyte marker CD68 in the peripheral blood mononuclear cell (PBMC) population. There was, however, an increase in the proportion of CD4+cells that were positive for CD25. There was no effect of status on the proportion of PBMCs that were CD8+when comparing preparturient cows to nonpregnant cows. However, preparturient cows had an increased percentage of PBMCs that were γδT cells and CD4+CD25+and a tendency for a lower percentage that were CD68+cells. Using immunolocalization with anti-CD68, it was found that pregnant cows had increased numbers of CD68+cells in the endometrial stroma as early as days 54–100 of gestation; this increase persisted through the last time examined (day 240 of gestation). Cells positive for CD68 were also positive for another macrophage/monocyte marker, CD14. In conclusion, pregnancy in the cow is associated with changes in peripheral and endometrial leukocyte numbers, which are similar to patterns observed in other species.

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.

In vitro and in vivo evidence for lack of endovascular remodeling by third trimester trophoblasts

The placental-decidual interaction through invading trophoblasts determines whether a physiological transformation of the uterine spiral arteries is established or not. Trophoblast-orchestrated artery remodeling is central to normal placentation. Dysregulated uteroplacental interaction and vascular remodeling are thought to be associated with the molecular events underlying the pathology of late pregnancy anomalies including preeclampsia. Although the exact gestational age at which trophoblast invasion ceases is not known, it remains unclear whether late pregnancy trophoblasts retain the ability to transform the uterine arteries. Here, we have developed a dual cell, in vitro culture system that mimics the vascular remodeling events during normal pregnancy. We demonstrate that first and third trimester trophoblasts respond differentially to interactive signals from endothelial cells when cultured on matrigel. Term primary trophoblasts or immortalized third trimester extravillous TCL1 trophoblasts not only fail to respond to signals from endothelial cells but also inhibit endothelial cell tube formation. In contrast, HTR8 cells, representing a first trimester trophoblast cell line with invasive properties, undergo spontaneous migration and synchronize with the endothelial cells in a capillary network. This disparity in behavior was confirmed in vivo using a matrigel plug assay. Poor expression of VEGF C and VEGF receptors coupled with high E-cadherin expression by term primary trophoblasts and TCL1 cells contributed to their restricted interactive and migratory properties. We further show that the kinase activity of VEGF R2 is essential for proactive crosstalk by HTR8 cells. This unique behavior of first trimester trophoblasts in the presence of endothelial cells offers a potential approach to study cell-cell interactions and to decipher modulatory components in the serum samples from adverse pregnancy outcomes.

Interleukin-10 may participate in regulating trophoblast invasion in human placentae throughout gestation

PROBLEM

A successful human pregnancy requires cytotrophoblasts from the fetal portion of the placenta to adopt tumor-like properties. But unlike tumor metastasis, cytotrophoblast invasion is highly regulated both spatially and temporally. The mechanisms that regulate human trophoblast invasion are understood poorly.

METHOD OF STUDY

With a view to obtain some findings on the mechanisms that regulate human trophoblast invasion, we applied the semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) method to compare the expression of invasion-associated genes in cytotrophoblasts isolated from first- and third-trimester placental tissues.

RESULTS

In trophoblast cells of first-trimester pregnancy, the mRNA contents of matrix metalloproteinase (MMP)-9 and urokinase-type plasminogen activator (uPA) were higher than that in the third-trimester cytotrophoblasts, while no difference of MMP-2 mRNA expression level was found between trophoblastic cells of different gestational ages. The expression level of plasminogen activator inhibitors-1 mRNA in first-trimester cytotrophoblasts was shown to be much lower than that in trophoblast cells prepared from third-trimester placental tissues. Furthermore, expression of both tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 in cytotrophoblasts were significantly up-regulated in third-trimester when compared with the first-trimester of pregnancy. To further investigate the factors that caused the change of invasion-associated genes expression in trophoblast cells, we found that interleukin-10 (IL-10) could decrease the content of MMP-9 mRNA in cytotrophoblasts of first-trimester gestation, and the magnitude of suppression increased with increasing IL-10 concentration.

CONCLUSION

The gradually reduced trophoblast invasion with gestational weeks might be on account of the change of proteolytic enzymes/activator/inhibitor genes expression. IL-10 could be one of the factors participating in the regulation of trophoblast invasion during gestational process.

Patterns of cytokine profiles differ with pregnancy outcome and ethnicity

BACKGROUND

Preterm birth (PTB) is hypothesized to be an inflammatory response disease. However, no single factor alone is likely to explain PTB risk. It is more probable that coordinated networks of cytokines affect risk.

METHODS

Therefore, we examined the relationships between amniotic fluid (AF) cytokines/chemokines and related biomarkers in PTB and normal term deliveries in African Americans and Caucasians. Data were obtained from African American (41 preterm labor and 91 term labor) and Caucasian (105 preterm labor and 100 term labor) pregnant mothers. Pro-inflammatory cytokines and related molecules interleukin (IL)-1, IL-6, IL-8, and tumor necrosis factor- (TNF)-alpha, TNF soluble receptors (sTNFR1 and sTNFR2), and anti-inflammatory cytokine IL-10 that were all previously associated with PTB were studied. Correlations between biomarkers were calculated; differences of correlation coefficients between AF from African American and Caucasian samples in preterm labor and term labor were measured.

RESULTS

Multiple differences were observed between African American and Caucasian preterm and term birth groups. In term birth the strongest differences were between pro- and anti-inflammatory correlations, whereas in PTB differences were equally distributed between pro-inflammatory/anti-inflammatory and pro-inflammatory/pro-inflammatory correlations. Three correlation patterns differed significantly between AF from PTB African Americans with and without microbial invasion of the intra-amniotic cavity (MIAC); no differences were observed in Caucasians with MIAC.

CONCLUSION

Correlation analyses of cytokine measurements suggest coordinated interplay during pregnancy; significant differences exist between African Americans and Caucasians. Such analyses can serve as a means of understanding risk factors in these populations.

Listeria monocytogenes infection in pregnant guinea pigs is associated with maternal liver necrosis, a decrease in maternal serum TNF-alpha concentrations, and an increase in placental apoptosis

Stillbirths and spontaneous abortions can result when pregnant women are exposed to the food borne pathogen, Listeria monocytogenes. Fetuses and neonates account for one-third of the 2500 cases annually. The objectives were to determine the dose dependent trends of immunological and pathological effects in pregnant guinea pigs after infection with L. monocytogenes. Timed pregnant guinea pigs were treated on gestation day (gd) 35 with doses of 10(4) to 10(8) colony forming units (CFUs) and sacrificed on gd 56. Hepatic lesions were found in dams treated with >or=10(5)CFUs. Apoptosis was detected in significantly more placentas from dams treated with >or=10(6)CFUs compared to controls. Maternal serum TNF-alpha concentrations were significantly decreased in all dose groups compared to controls. In conclusion, increases in premature delivery, maternal hepatic effects and placental apoptosis along with a decrease in TNF-alpha concentrations were associated with L. monocytogenes infection in pregnant guinea pigs.

Evolution of non-cytotoxic uterine natural killer cells

The immune tolerance and de novo vascularization are two highly intriguing processes at the maternal-fetal interface that appear to be central to normal pregnancy outcome. Immune tolerance occurs despite the local presence of an active maternal immune system including macrophages, dendritic cells and specialized CD56(bright)CD16(-) uterine natural killer (uNK) cells (65-70%). Recent observations indicate that the phenotypic and functional repertoire of uNK cells is distinct from peripheral blood NK and endometrial NK cells, challenging the understanding of their temporal occurrence and function. Origin and specialized programming of uNK cells continue to be debated. uNK cells, replete with an armamentarium to kill the foreign, tolerate the conceptus and facilitate pregnancy. Why do these uNK cells remain non-cytotoxic? Are these NK cells 'multitasking' in nature harboring beneficial and detrimental roles in pregnancy? Are there distinct subpopulations of NK cells that may populate the decidua? We propose that the endometrium/decidua functions as an 'inducible tertiary lymphoid tissue' that supports the recruitment and expansion of CD56(bright)CD16(-) NK cells and induces transcriptional up-regulation of angiogenic machinery in response to exposure to local hormonal factors, cytokine milieu and perhaps hypoxia. The angiogenic features of uNK cells could further result in a 'multitasking' phenotype that still remains to be characterized. This article discusses the factors and pathways that bridge the angiogenic and non-cytotoxic response machineries at the maternal-fetal interface.

Gene expression profiling of human decidual macrophages: evidence for immunosuppressive phenotype

Background

Although uterine macrophages are thought to play an important regulatory role at the maternal-fetal interface, their global gene expression profile is not known.

Methodology/Principal Findings

Using micro-array comprising approximately 14,000 genes, the gene expression pattern of human first trimester decidual CD14+ monocytes/macrophages was characterized and compared with the expression profile of the corresponding cells in blood. Some of the key findings were confirmed by real time PCR or by secreted protein. A unique gene expression pattern intrinsic of first trimester decidual CD14+ cells was demonstrated. A large number of regulated genes were functionally related to immunomodulation and tissue remodelling, corroborating polarization patterns of differentiated macrophages mainly of the alternatively activated M2 phenotype. These include known M2 markers such as CCL-18, CD209, insulin-like growth factor (IGF)-1, mannose receptor c type (MRC)-1 and fibronectin-1. Further, the selective up-regulation of triggering receptor expressed on myeloid cells (TREM)-2, alpha-2-macroglobulin (A2M) and prostaglandin D2 synthase (PGDS) provides new insights into the regulatory function of decidual macrophages in pregnancy that may have implications in pregnancy complications.

Conclusions/Significance

The molecular characterization of decidual macrophages presents a unique transcriptional profile replete with important components for fetal immunoprotection and provides several clues for further studies of these cells.

BeWo trophoblast cell susceptibility to Toxoplasma gondii is increased by interferon-gamma, interleukin-10 and transforming growth factor-beta1

The present study aimed to investigate BeWo trophoblast cell susceptibility to Toxoplasma gondii infection under stimulation with anti-inflammatory cytokines in comparison with HeLa cells. Both cell types were submitted to different treatments with recombinant cytokines [interleukin (IL)-10 and transforming growth factor (TGF)-beta1] or the respective antibodies (anti-IL-10 and anti-TGF-beta) before and after T. gondii infection. The effect of interferon (IFN)-gamma was also assessed alone or in combination with anti-inflammatory cytokines or the respective antibodies after the parasite infection. Cells were fixed, stained and parasites quantified under light microscopy to evaluate intracellular replication (mean number of parasites per cell in 100 infected cells) and infection index (percentage of infected cells per 100 examined cells). In contrast with HeLa cells, treatments with IL-10 or TGF-beta1 induced a considerable augmentation in both T. gondii intracellular replication and invasion into BeWo cells. In addition, treatment with IFN-gamma alone or associated with IL-10 or TGF-beta1 increased the same parameters in BeWo cells, whereas the opposite effect was observed in HeLa cells. When endogenous IL-10 or TGF-beta was blocked, both BeWo and HeLa cells were able to control the parasite infection only in the presence of IFN-gamma. Together, these results indicate that the higher susceptibility of BeWo cells to T. gondii may be due to immunomodulation mechanisms, suggesting that the role of trophoblast cells in maintaining a placental microenvironment favourable to pregnancy may facilitate the infection into the placental tissues.

Inflammation in pregnancy: its roles in reproductive physiology, obstetrical complications, and fetal injury

Fetal development and growth occur in a sterile amniotic cavity while first exposure to microorganisms happens at birth. However, at least 25% of all preterm births, the leading cause of perinatal morbidity and mortality worldwide, occur in mothers with microbial invasion of the amniotic cavity. Microbial attack of the fetus takes place in approximately 10% of pregnancies with intra-amniotic infection, and the human fetus is capable of deploying an inflammatory response (cellular and humoral) in the mid-trimester of pregnancy. The onset of premature labor in the context of infection is mediated by pro-inflammatory cytokines, such as interleukin (IL)-1beta and tumor necrosis factor alpha (TNF-alpha), as these cytokines are produced by intrauterine tissues in response to microbial products, can stimulate prostaglandin production, and induce labor in animals. Moreover, knockout experiments suggest that infection is less likely to lead to premature labor when the IL-1 and TNF signaling pathways are disrupted. A fetal inflammatory systemic response occurs in a fraction of fetuses exposed to microorganisms in utero, and is associated with the impending onset of labor as well as multisystem organ involvement. Neonates born with funisitis, the histologic marker of such inflammation, are at increased risk for neurologic handicap and cerebral palsy. Evidence has begun to accumulate that gene-environment interactions determine the likelihood of preterm labor and delivery and, probably, the risk of fetal injury. Fetal inflammation has emerged as a major mechanism of disease responsible for complications in the perinatal period (in utero and in the first 28 days of life), as well as in infancy. Moreover, reprogramming of the fetal immune response may predispose to diseases in adulthood.

Maternal serum soluble CD30 is increased in normal pregnancy, but decreased in preeclampsia and small for gestational age pregnancies

OBJECTIVE

Women with preeclampsia and those who deliver small for gestational age (SGA) neonates are characterized by intravascular inflammation (T helper 1 (Th1)-biased immune response). There is controversy about the T helper 2 (Th2) response in preeclampsia and SGA. CD30, a member of the tumor necrosis factor receptor superfamily, is preferentially expressed in vitro and in vivo by activated T cells producing Th2-type cytokines. Its soluble form (sCD30) has been proposed to be an index of Th2 immune response. The objective of this study was to determine whether the maternal serum concentration of sCD30 changes with normal pregnancy, as well as in mothers with preeclampsia and those who deliver SGA neonates.

METHODS

This cross-sectional study included patients in the following groups: (1) non-pregnant women (N = 49); (2) patients with a normal pregnancy (N = 89); (3) patients with preeclampsia (N = 100); and (4) patients who delivered an SGA neonate (N = 78). Maternal serum concentration of sCD30 was measured by a specific and sensitive enzyme-linked immunoassay. Non-parametric tests with post-hoc analysis were used for comparisons. A p value <0.05 was considered statistically significant.

RESULTS

(1) The median sCD30 serum concentration of pregnant women was significantly higher than that of non-pregnant women (median 29.7 U/mL, range 12.2-313.2 vs. median 23.2 U/mL, range 14.6-195.1, respectively; p = 0.01). (2) Patients with preeclampsia had a significantly lower median serum concentration of sCD30 than normal pregnant women (median 24.7 U/mL, range 7.6-71.2 vs. median 29.7 U/mL, range 12.2-313.2, respectively; p < 0.05). (3) Mothers with SGA neonates had a lower median concentration of sCD30 than normal pregnant women (median 23.4 U/mL, range 7.1-105.3 vs. median 29.7 U/mL, range 12.2-313.2, respectively; p < 0.05). (4) There was no significant correlation (r = -0.059, p = 0.5) between maternal serum sCD30 concentration and gestational age (19-38 weeks) in normal pregnant women.

CONCLUSIONS

(1) Patients with preeclampsia and those who deliver an SGA neonate had a significantly lower serum concentration of sCD30 than normal pregnant women. (2) This finding is consistent with the view that preeclampsia and SGA are associated with a polarized Th1 immune response and, perhaps, a reduced Th2 response.

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

PROBLEM

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

METHOD OF STUDY

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

RESULTS

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

CONCLUSION

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

Elucidation of the molecular mechanisms of preeclampsia using proteomic technologies

Preeclampsia, a disease of pregnancy, is a multisystem disorder associated with elevated maternal blood pressure, proteinurea, oedema, and fetal abnormalities. It is a major cause of mortality, morbidity, perinatal death, and premature delivery. Despite active research in the past decade, there is yet no definitive cure for preeclampsia. The disease has been treated symptomatically with antihypertensives, antieclamptics, bed rest, and a whole gamut of isolated therapies. In an attempt to understand the molecular basis of this disease and many other fatal diseases including cancer and heart disease, the scientific community has been turning to understanding the genome and more lately the "proteome". Proteomics enables researchers to identify all proteins expressed in a cell or organ and detect any PTM in the protein expression patterns. Deciphering the placental proteome and studying the differences in protein expression patterns in the normal as against the preeclamptic proteome might possibly in future lead to early detection and therapeutic targeting of preeclampsia.

Role of placentally produced inflammatory and regulatory cytokines in pregnancy and the etiology of preeclampsia

Human pregnancy is a metabolic and immune challenge for the mother who has to accommodate in her womb a semi-allogeneic fetus whose energy needs increase tremendously with gestation. Recent compelling research has suggested that proper inflammatory changes and oxidative balance are a requisite for successful pregnancy. The placenta is an integral component of this inflammatory response as it actively produces a variety of cytokines and immunomodulatory hormones. In preeclampsia, a life-threatening disorder of pregnancy that is characterized by widespread damage and dysfunction of the maternal endothelium, placental oxidative stress and aberrant cytokine expression induces an exaggerated maternal systemic inflammatory response to pregnancy.

Maternal influence in the transmission of asthma susceptibility

Asthma is one of the most common chronic diseases in children, with increasing morbidity and mortality. A genetic predisposition and exposure to allergens have been implicated as major risk factors for the development of asthma. However, increasing evidence indicates that the mother plays a crucial role in mediating the development of fetal-infant immune responses to inhaled allergens. The exact nature and mechanism of this maternal influence and how it might be associated with the development of allergic sensitization and asthma are not clear. Under normal conditions, the maternal environment during pregnancy promotes an initial Th2 skewed immune response in the offspring which transitions to a nonallergic Th1 type response after birth. However, the allergic mother's influence may delay the normal transition to a nonallergic immune response to inhaled allergens in her children, thus increasing the risk for the development of allergic sensitization and/or asthma. Understanding the underlying mechanisms by which the maternal immune environment can influence the development of the fetal-infant immune response to inhaled allergens may lead to identifying new targets for the prevention of allergic sensitization and asthma.

Influence of labor on neonatal neutrophil apoptosis, and inflammatory activity

Neutrophil apoptosis is impaired in neonates, and this contributes to prolonged inflammation and tissue injury in infants after infection or trauma. In the present studies, we investigated whether labor generates mediators that further suppress apoptosis. We found that neutrophil apoptosis was reduced in neonates exposed to labor, when compared with infants delivered by cesarean section before labor. This was not due to alterations in caspase-3 or inhibitor of apoptosis protein-2 (IAP-2). In contrast, labor primed neutrophils to express tumor necrosis factor alpha (TNF-alpha), suggesting that proinflammatory mediators contribute to reduced apoptosis after labor. Eicosanoids generated via cyclooxygenase-2 (Cox-2) and lipoxygenase (Lox) also regulate neutrophil apoptosis. 15-Lox, which generates proapoptotic lipoxins, but not Cox-2, was greater in neutrophils before labor, relative to cells exposed to labor. Anti-inflammatory eicosanoids exert their effects in part via peroxisome proliferator-activated receptor gamma (PPAR-gamma). Expression of gelatinase-associated lipocalin and catalase, two markers of PPAR-gamma activity, were increased in neonatal neutrophils before labor, relative to cells exposed to labor. These findings suggest that the anti-inflammatory environment is maintained before labor, in part, by eicosanoids. Although increased neutrophil longevity after labor is important for host defense in the immediate newborn period, it may contribute to inflammatory or oxidative injury in susceptible infants.

Spontaneous and LPS-induced secretion of cytokines by villous chorion tissue

Secretion of IL-1alpha, IL-1beta, IL-6, IL-10, and TNF-alpha cytokines by villous chorion cultures (7-14 weeks) during normal pregnancy and in spontaneous abortions was studied. Secretion of IL-1alpha and IL-6 increased 4.5 and 7.3 times in miscarriages, while secretion of IL-1beta, IL-10, and TNF-alpha decreased. LPS stimulated the production of IL-1alpha and IL-6 in samples obtained during surgical abortion. LPS stimulated IL-1alpha and TNF-alpha secretion in miscarriages, while the level of IL-6 production decreased significantly. It is hypothesized that increased production of IL-1alpha and IL-6 and attenuation of the antiinflammatory effect of IL-10 play an important role in the pathogenesis of miscarriages at early stages of gestation. The results suggest that cytokine regulation of the fetus rejection is different at early and late stages of gestation.

CD4+ CD25+ regulatory T cells in human pregnancy: development of a Treg-MLC-ELISPOT suppression assay and indications of paternal specific Tregs

The current study was aimed at developing a one-way mixed leucocyte culture-enzyme-linked immunospot (MLC-ELISPOT) assay for the study of CD4(+) CD25(+) regulatory T (T(reg)) cells and applying this method in the study of antifetal immune reactions during human pregnancy. Twenty-one pregnant women and the corresponding fathers-to-be, and 10 non-pregnant control women and men, participated in the study. CD4(+) CD25(+) cells were isolated from peripheral blood mononuclear cells (PBMC) by immunomagnetic selection. Maternal/control PBMC were stimulated with paternal or unrelated PBMC in MLC. Secretion of interleukin-4 (IL-4) and interferon-gamma (IFN-gamma) from responder cells, with or without the presence of autologous T(reg) cells, was analysed by ELISPOT. PBMC from pregnant women showed increased secretion of IL-4 compared to controls. In pregnant and non-pregnant controls, T(reg) cells suppressed IFN-gamma reactivity against paternal and unrelated alloantigens. Interestingly, T(reg) cells suppressed IL-4 secretion against paternal but not unrelated alloantigens during pregnancy. We have successfully developed a model for studying T(reg) cells in antifetal cytokine reactions during pregnancy. Results indicate that T(reg) cells contribute to strict regulation of both T helper type 1-like and type 2-like antifetal immune reactions. Interestingly, T helper type 2-like cells specific to unrelated alloantigens are able to escape the suppression of T(reg) cells, which would allow for IL-4, alongside CD4(+) CD25(+) T(reg) cells, to control potentially detrimental IFN-gamma reactions during pregnancy.

Suppression of IL-2 and IFN-gamma production in women with spontaneous preterm labor

AIMS

To determine the TH-1/TH-2 cytokine pattern in peripheral blood leukocytes (PBL) in late second- and third trimester in normal pregnancies, in comparison to patients with spontaneous preterm delivery (PTD; < 37 completed weeks' gestation).

METHODS

A cross-sectional retrospective study was performed in a tertiary care obstetric unit with healthy non-pregnant women (n=7); healthy pregnant women (n=25); patients (n=25) with preterm labor (defined as uterine contractions or changes in cervical length). The phenotypic analysis of TH-1/TH-2 immune deviation was examined in PBL.

RESULTS

26% PTD (n=13) were recorded. Patients delivering at term (n=37, 74%) were characterized by an upregulation of IL-2, IFN-gamma and IL-4 production during weeks 20-25, followed by a strong suppression in cytokine production, except for TGF-beta. Towards the end of pregnancy cytokine levels returned to normal as observed in non-pregnant women. In contrast, PTD showed an inverse pattern for IL-2 and IFN-gamma with marked suppression in IL-2 and IFN-gamma production between weeks 20-25, followed by a strong stimulation of these cytokines. No differences were observed in IL-4 and TGF-beta production.

CONCLUSION

An inverse pattern in IL-2 and IFN-gamma production in PBLs between weeks 20-30 is seen in PTD as compared to patients delivering at term.

The role of inflammation and infection in preterm birth

Inflammation has been implicated in the mechanisms responsible for preterm and term parturition, as well as fetal injury. Out of all of the suspected causes of preterm labor and delivery, infection and/or inflammation is the only pathological process for which both a firm causal link with preterm birth has been established and a molecular pathophysiology defined. Inflammation has also been implicated in the mechanism of spontaneous parturition at term. Most cases of histopathological inflammation and histological chorioamnionitis, both in preterm and term labor, are sub-clinical in nature. The isolation of bacteria in the amniotic fluid, known as microbial invasion of the amniotic cavity, is a pathological finding; the frequency of which is dependent upon the clinical presentation and gestational age. This article reviews the role of inflammation in preterm and term parturition.

The preterm parturition syndrome

The implicit paradigm that has governed the study and clinical management of preterm labour is that term and preterm parturition are the same processes, except for the gestational age at which they occur. Indeed, both share a common pathway composed of uterine contractility, cervical dilatation and activation of the membranes/decidua. This review explores the concept that while term labour results from physiological activation of the components of the common pathway, preterm labour arises from pathological signalling and activation of one or more components of the common pathway of parturition. The term "great obstetrical syndromes" has been coined to reframe the concept of obstetrical disease. Such syndromes are characterised by: (1) multiple aetiology; (2) long preclinical stage; (3) frequent fetal involvement; (4) clinical manifestations that are often adaptive in nature; and (5) gene-environment interactions that may predispose to the syndromes. This article reviews the evidence indicating that the pathological processes implicated in the preterm parturition syndrome include: (1) intrauterine infection/inflammation; (2) uterine ischaemia; (3) uterine overdistension; (4) abnormal allograft reaction; (5) allergy; (6) cervical insufficiency; and (7) hormonal disorders (progesterone related and corticotrophin-releasing factor related). The implications of this conceptual framework for the prevention, diagnosis, and treatment of preterm labour are discussed.

Inhibition of term decidual NK cell cytotoxicity by soluble HLA-G1

OBJECTIVES

Soluble (s)HLA-G1 is produced by trophoblast cells. Aim was to analyze the capacities and mechanisms of sHLA-G1 to regulate interleukin (IL)-2-induced cytotoxicity of natural killer (NK) cells from human deciduas.

METHODS

Natural killer cells were isolated from decidual layers of term placentae, stimulated or not with IL-2 and supplemented with various concentrations of recombinant soluble HLA-G1 (sHLA-G1). For NK cell cytotoxicity assays, K562 cells were used as targets. Expression of signal transducer and activator of transcription 3 (STAT3) and perforin was analyzed by Western blotting. Apoptosis was examined by assessment of poly(ADP-ribose) polymerase cleavage. NK cells were analyzed by flow cytometry for IL-2receptor-alpha (IL-2R alpha; CD25) and transferrin receptor CD71 expression.

RESULTS

Interleukin-2 increases CD71, STAT3, perforin expression and cytotoxic potential of NK cells. Expression of CD71, STAT3 and perforin decreased simultaneously with cytotoxicity and dose-dependently when sHLA-G1 (1.6 micro g/mL-1.6 ng/mL) was added to IL-2 stimulated cultures. sHLA-G1 did not induce apoptosis and CD25 expression was not affected.

CONCLUSION

Interleukin-2R alpha expression is not controlled by sHLA-G1, but its signal transducer STAT3 as well as several downstream effects, such as perforin expression, proliferation and cytotoxicity. The control of STAT3 bioavailability through sHLA-G1 may be a key regulator of the mentioned effects.

Aberrant Uterine Natural Killer (NK)-Cell Expression and Altered Placental and Serum Levels of the NK-Cell Promoting Cytokine Interleukin-12 in Pre-Eclampsia

PROBLEM

Natural killer (NK) cells are the most abundant lymphocyte population at the maternal-fetal interface. They are suggested to be important during placentation by controlling trophoblast invasion. If placentation is suboptimal, pre-eclampsia can occur.

METHOD OF STUDY

Decidual NK (dNK) cells were examined at delivery in 46 women, 22 pre-eclamptic women and 24 healthy controls, by staining for CD56 and CD94 with immunohistochemistry (IHC). Furthermore, we investigated the placental expression and the serum levels of the NK-cell activating cytokines interleukin(IL)-12, IL-15, IL-18 and the anti-inflammatory cytokine IL-10 by IHC and enzyme-linked immunosorbent assay (ELISA), respectively.

RESULTS

Pre-eclamptic women had higher number of CD56+ and CD94+ cells in the decidua, indicating an altered receptor expression of dNK cells. We also demonstrate for the first time that the villous trophoblasts show strong immunostaining for IL-12 in placentae from healthy controls, while women suffering from pre-eclampsia have significantly less IL-12. However, pre-eclamptic women had significantly elevated IL-12 and IL-15 levels in serum.

CONCLUSION

Results show increased numbers and altered phenotype of dNK cells in pre-eclampsia, supporting the importance of these cells for a healthy pregnancy. The altered receptor expression of dNK cells together with diminished placental IL-12 expression could implicate an altered NK cell-regulation in pre-eclampsia.

Inflammation in preterm and term labour and delivery

Inflammation has been implicated in the mechanisms responsible for preterm and term parturition, as well as fetal injury. Out of all of the suspected causes of preterm labour and delivery, infection and/or inflammation is the only pathological process for which both a firm causal link with preterm birth has been established and a molecular pathophysiology defined. Inflammation has also been implicated in the mechanism of spontaneous parturition at term. Most cases of histopathological inflammation and histological chorioamnionitis, both in preterm and term labour, are sub-clinical in nature. The isolation of bacteria in the amniotic fluid, known as microbial invasion of the amniotic cavity, is a pathological finding; the frequency of which is dependent upon the clinical presentation and gestational age. There is a window of time during which it may be possible to detect a 'molecular signature of inflammation' by analysis of the transcriptome before histological evidence is observed. This article reviews the role of inflammation in preterm and term parturition. It is possible that modulation of inflammation using anti-inflammatory cytokines, corticoids, antioxidants and/or other factors may complement antibiotic therapy and limit fetal injury.

Essential Role for IL-10 in Resistance to Lipopolysaccharide-Induced Preterm Labor in Mice

IL-10 is highly expressed in the uterus and placenta and is implicated in controlling inflammation-induced pathologies of pregnancy. To investigate the role of IL-10 in regulating preterm labor, the response of IL-10 null mutant mice to low-dose LPS in late gestation was evaluated. When IL-10 null mutant C57BL/6 (IL-10(-/-)) and control (IL-10(+/+)) mice were administered LPS on day 17 of pregnancy, the dose of LPS required to elicit 50% preterm fetal loss was 10-fold lower in IL-10(-/-) mice than in IL-10(+/+) mice. Surviving fetuses in IL-10(-/-) mice exhibited fetal growth restriction at lower doses of LPS than IL-10(+/+) mice. Marked elevation of LPS-induced immunoactive TNF-alpha and IL-6 was evident in the serum, uterus, and placenta of IL-10(-/-) mice, and TNF-alpha and IL-6 mRNA expression was elevated in the uterus and placenta, but not the fetus. Serum IL-1alpha, IFN-gamma, and IL-12p40 were increased and soluble TNFRII was diminished in the absence of IL-10, with these changes also reflected in the gestational tissues. Administration of rIL-10 to IL-10(-/-) mice attenuated proinflammatory cytokine synthesis and alleviated their increased susceptibility to preterm loss. Exogenous IL-10 also protected IL-10(+/+) mice from fetal loss. These data show that IL-10 modulates resistance to inflammatory stimuli by down-regulating proinflammatory cytokines in the uterus and placenta. Abundance of endogenous IL-10 in gestational tissues is therefore identified as a critical determinant of resistance to preterm labor, and IL-10 may provide a useful therapeutic agent in this common condition.

Tumour necrosis factor-alpha impairs chorionic gonadotrophin beta-subunit expression and cell fusion of human villous cytotrophoblast

Growth factors expressed at the fetal-maternal interface modulate hormone expression of placental trophoblasts. The aim of this study was to investigate the effects of different cytokines on hCG subunit mRNA expression in differentiating villous cytotrophoblasts. Quantitative real-time PCR revealed a 1.8- and 6.9-fold increase of hCG-alpha and hCG-beta mRNA levels, respectively, between 36 and 60 h of term trophoblast syncytialization. Compared with controls, neither interleukin (IL)-1beta, IL-2, IL-4, IL-6, IL-10, IL-13 and IL-15 nor tumour necrosis factor (TNF)-alpha significantly altered hCG-alpha mRNA expression. Similarly, the ILs did not affect hCG-beta transcript levels. In contrast, TNF-alpha suppressed hCG-beta mRNA 3.8- and 1.8-fold at 36 and 60 h of term trophoblast differentiation. Accordingly, hCG secretion was impaired by TNF-alpha but not by the different ILs. Moreover, TNF-alpha reduced luciferase expression of reporter plasmids harbouring the proximal hCG-beta5 promoter to 35 and 77%, respectively, in primary term trophoblasts and trophoblastic SHGPL-5 cells. In addition, counting of nuclei in syncytialized, desmoplakin-negative areas revealed a 1.9-fold reduction of term trophoblast fusion in the presence of TNF-alpha. Similarly, floating explant cultures prepared from first trimester-denuded villi recovered the syncytium 2.8-fold less efficiently during 72 h of cytokine treatment. Concomitantly, TNF-alpha impaired induction of endogenous and secreted hCG-beta protein levels in these cultures. The data suggest that TNF-alpha decreases hCG-beta mRNA and protein expression by reducing gene transcription and trophoblast cell fusion. Suppression of these processes by TNF-alpha could partly explain the adverse effects of the cytokine on placental function and pregnancy outcome.

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

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

Plasmodium falciparum-infected Red Blood Cells Selected for Binding to Cultured Syncytiotrophoblast Bind to Chondroitin Sulfate A and Induce Tyrosine Phosphorylation in the Syncytiotrophoblast

An important pathogenic complication of malaria during human pregnancy is sequestration of Plasmodium-infected red blood cells (iRBCs) in the placental intervillous spaces. This sequestration is thought to be mediated in part by binding of the iRBCs to receptors expressed on the syncytiotrophoblast (ST) membrane. We report here the use of a dynamic system to study the consequences of this cytoadherence on ST function using human syncytiotrophoblast and the choriocarcinoma cell line, BeWo. Laboratory isolates of Plasmodium falciparum were selected for their ability to bind to ST and used to investigate binding-induced cellular changes in the ST. Treatment of the ST cells with chondroitinase ABC suggested that the selected parasites bind predominantly to chondroitin sulfate A, but other receptors for parasite binding may be involved. Intracellular signaling in the ST induced by iRBCs binding was investigated by assessing tyrosine phosphorylation of ST proteins following iRBC binding. We demonstrate for the first time that iRBC cytoadherence to syncytiotrophoblast enhances tyrosine phosphorylation of a series of proteins in these cells. This approach will be useful in further studies of ST function in the malaria-infected placenta, the dynamics of selection of syncytiotrophoblast-binding parasites, and the identification of new receptors for parasite cytoadherence in the placenta.

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

PROBLEM

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

METHOD OF STUDY

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

RESULTS

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

CONCLUSION

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

Hypoxia promotes interleukin-6 and -8 but reduces interleukin-10 production by placental trophoblast cells from preeclamptic pregnancies

OBJECTIVE

Placental hypoxia and altered placental cytokine productions have been considered to play a significant role in the pathophysiology of preeclampsia. The objective of this study was to determine whether hypoxia could modify interleukin (IL)-6, IL-8, and IL-10 production by placental trophoblast cells (TCs) from normal and preeclamptic (PE) pregnancies.

METHODS

Placentas were obtained from nine normal and nine PE pregnancies immediately after delivery. Placental TCs were isolated and cultured under normoxic (21% O(2)/air) and hypoxic (2% O(2)/5% CO(2)/92% N(2)) conditions for 48 hours. TC productions of IL-6, IL-8, and IL-10 were measured by enzyme-linked immunosorbent assay (ELISA). Unpaired t tests or paired t test was used for the statistical analysis and data are expressed as means +/- SE (pg/mug cellular protein). A P value less than .05 was considered statistically significant.

RESULTS

PE-TCs produced significantly more IL-6, IL-8, and IL-10 than those of normal-TCs when they were cultured under normoxic condition, P < .05. Both normal-TCs and PE-TCs produced more IL-6 and IL-8 when they were cultured under hypoxic conditions. Hypoxia reduced IL-10 production by PE-TCs, but had no effect on IL-10 production by normal-TCs.

CONCLUSIONS

Hypoxia promotes both IL-6 and IL-8 but reduces IL-10 production by placental TCs from PE pregnancies.

The role of apoptosis in the regulation of trophoblast survival and differentiation during pregnancy

Apoptosis is important for normal placental development, but it may also be involved in the pathophysiology of pregnancy-related diseases. Normal placental development is dependent upon the differentiation and invasion of the trophoblast, the main cellular component of the placenta. Trophoblast apoptosis increases in normal placentas as gestation proceeds, and a greater incidence of trophoblast apoptosis has been observed in pregnancies complicated by preeclampsia or intrauterine growth retardation (IUGR). In response to different stimuli, apoptosis may be initiated extrinsically by the death receptor pathway or intrinsically by the mitochondrial pathway. The central executioners of apoptosis are the caspases, which cleave numerous vital cellular proteins to affect the apoptotic cascade. By inhibiting caspase activation, several endogenous inhibitors, including flice-like inhibitory proteins (FLIPs), inhibitors of apoptosis (IAPs), and antiapoptotic Bcl-2 family members, can prevent further propagation of the death signal. Macrophages present at the maternal-fetal interface may also contribute to trophoblast survival by removing apoptotic cells and producing cytokines and growth factors, which influence the progression of the apoptotic cascade. This review focuses on the role of apoptosis in trophoblast development and differentiation, the molecular mechanisms by which normal trophoblast apoptosis can occur, and how it is regulated to prevent excessive trophoblast apoptosis and possible pregnancy complications.

Maternal tolerance to H-Y is independent of IL-10

It has been suggested that the maternal immune system favors noncytotoxic, "TH-2" immune responses in order to tolerate the developing fetus. In some strains of mice, pregnant females will reject a male skin graft, even as they tolerate their male fetuses. This rejection is based on responsiveness to the male antigen H-Y. In this study we test whether functional maternal tolerance of male fetuses is critically dependent on the TH-2 cytokine Interleukin 10 (IL-10). Normal and IL-10-deficient (10-KO) females were sensitized against H-Y by intraperitoneal injection of male spleen cells before mating with 10-KO males. Litters born to 10-KO females were of comparable size to those born to normal females of the same genetic background. The proportion of males per litter was not adversely affected by IL-10 deficiency. Taken together, our work and others suggest that IL-10 may not be critically important for maternal tolerance of the fetus and extends the evidence against the idea that successful mouse pregnancy depends on TH-2 deviation of the maternal immune system.

Th1 cytokines are essential for placental immunity to Listeria monocytogenes

The fetal allograft poses an immunological challenge: how is it protected while immunity to pathogens, particularly those that replicate in the placenta, is maintained? Several theories have been proposed to explain this fetal protection, including a pregnancy-based bias towards a Th2 rather than Th1 cytokine profile in order to avoid generating cytotoxic T cells that could threaten the fetus. Listeria monocytogenes preferentially replicates in the placenta and systemically requires a Th1 response for sterile eradication. In the placenta, the Th1 cytokines tumor necrosis factor alpha (TNF-alpha) and gamma interferon (IFN-gamma) are also synthesized in response to this pathogen, without fetal loss. Here we show, by using mice homozygous for null mutations in either the cytokine or cytokine receptor genes, a requirement for both TNF-alpha and IFN-gamma signaling for an effective placental immune response to L. monocytogenes. However, T cells were not recruited to the placenta. Genetic studies in which the fetal component of the placenta was genetically different from the mother indicated that both the production of and response to these cytokines were maternal. Despite the requirement for these cytokines, the early recruitment of neutrophils to the placenta was normal. Consequently, the bacterium appeared to be delayed in its colonization of this organ and did not fully gain hold until 72 h postinfection. These data show a requirement for Th1 cytokines during pregnancy for effective immunity and indicate that a bias away from Th1 cytokine synthesis is not a necessary prerequisite of pregnancy.

Maternal CD46H*2 and IL1B-511*1 homozygosity in T helper 1-type immunity to trophoblast antigens in recurrent pregnancy loss

BACKGROUND

Women with recurrent pregnancy loss (RPL) and T-helper (Th)1-type immunity to trophoblast antigens have an increased frequency of the IL1B-511*1 promoter variant. Since CD46 gene products also regulate maternal immune responses including Th1 immunity, we investigated whether CD46 gene polymorphisms are also associated with RPL in women with and without Th1 immunity to trophoblast, and the possibility of a synergistic effect with the IL1B-511*1 promoter variant.

METHODS

A case-controlled study was performed to document HindIII site polymorphism in intron 1 of the CD46 gene in 131 women with RPL and 72 fertile controls. Clinical information, Th1-type immune responsiveness to trophoblast in women with RPL history, and IL1B promoter allelotypes for this cohort were documented in a previous study.

RESULTS

The frequency of the CD46H*2 allele and CD46H*2 homozygosity were significantly increased in women with RPL compared with fertile controls (P<0.028 and P<0.011). CD46H*2 homozygosity was highly associated with RPL-Th1(+) (32.4 versus 9.7% in fertile controls, P<0.0045). Logistic regression analysis revealed that women homozygous for both the IL1B-511*1 and CD46H*2 alleles had an extremely high risk of RPL-Th1(+) [exponential coefficients (EC)=24]. Among women with RPL, homozygosity at both alleles, but not each alone, significantly increased the risk of Th1 immunity to trophoblast antigens (EC=16), suggesting a possible genetic interaction between these two alleles in the development of Th1 immunity.

CONCLUSIONS

The combination of homozygosity for both IL1B-511*1 and CD46H*2 alleles is a high risk factor for RPL-Th1(+).

Uterine NK Cells Mediate Inflammation-Induced Fetal Demise in IL-10-Null Mice

Specialized NK cells are recruited in high numbers to the mammalian embryo implantation sites, yet remain pregnancy compatible. It is not well understood whether uterine NK (uNK) cells become adversely activated and mediate fetal demise, a common complication of early pregnancy. In this study we show that mating of IL-10(-/-) mice resulted in fetal resorption or intrauterine growth restriction in response to very low doses of LPS. Pregnancy in congenic wild-type mice was normal even at 10-fold higher LPS doses. Fetal resorption in IL-10(-/-) mice was associated with a significant increase in uNK cell cytotoxic activation and invasion into the placenta. Depletion of uNK cells, TNF-alpha neutralization, or IL-10 administration rescued pregnancy in LPS-treated IL-10(-/-) animals. Our results identify an immune mechanism of fetal demise involving IL-10 deficiency, NK cells, and inflammation. These results may provide insight into adverse pregnancy outcomes in humans.

Placental deficiency of interleukin-10 (IL-10) in preeclampsia and its relationship to an IL10 promoter polymorphism

The placenta is pivotal in the acceptance of the feto-placental unit by the maternal immune system. Imbalance at the maternal-fetal interface of tissue pro- and anti-inflammatory cytokines may be partly involved in disease causation. Previous work has shown conflicting levels of IL-10. IL-10 levels have been shown to increase, decrease, or remain unchanged in women with preeclampsia. This study examines the difference in serum and placental IL-10 expression in women with preeclampsia and investigates if the IL10 (-1082) A promoter polymorphism contributes to lower concentrations. In a prospective case-control study of 12 women with preeclampsia and 31 controls we assessed serum IL-10 by ELISA, placental mRNA by quantitative PCR and protein by immunohistochemistry as well as placental IL10 promoter genotype. Comparisons were made with non-parametric tests where necessary and chi-square. We found a significant reduction in placental IL-10 mRNA and protein expression in women with preeclampsia compared to controls. Women with the AA IL-10 promoter genotype expressed less placental IL-10 mRNA compared to women with AG or GG genotype. There was no difference in serum IL-10 concentrations between different genotypes. Preeclampsia is associated with a deficiency of placental IL-10. Placental AA genotype in the promoter region results in significantly less placental IL-10.

Indications of an altered immune balance in preeclampsia: A decrease in in vitro secretion of IL-5 and IL-10 from blood mononuclear cells and in blood basophil counts compared with normal pregnancy

It has been suggested that maladaptation of the maternal immune response during pregnancy might be a causal factor for preeclampsia. This study was designed to examine the systemic immune status at both the innate level and the adaptive level in pregnancies complicated by preeclampsia (n=15) and normal pregnancies (n=15). Spontaneous and in vitro-induced secretion of IL-5, IL-6, IL-10, IL-12, IL-13 and TNF-alpha, in response to paternal blood cells and the vaccination antigens purified protein derivate of tuberculin (PPD) and tetanus toxoid (TT), was detected in cell culture supernatants from blood mononuclear cells by ELISA. Preeclamptic women showed reduced numbers of basophil granulocytes in the blood (p=0.004) and lower spontaneous secretion of IL-5 from blood mononuclear cells (p=0.016). In addition, paternal antigen-induced secretion of IL-10 was decreased in preeclampsia compared with normal pregnancy (p=0.012). No further differences between preeclampsia and normal pregnancy were found for any stimuli or cytokines. The present findings of reduced basophil numbers and lower spontaneous in vitro secretion of IL-5 in preeclampsia compared with normal pregnancy indicate a decrease in systemic Th2 immunity in preeclampsia. Furthermore, the decrease in paternal antigen-induced secretion of the immunosuppressive cytokine IL-10 in preeclampsia indicates a fetus-specific decrease in immunosuppression mediated by blood mononuclear cells. Whether these systemic changes are a cause or a consequence of preeclampsia remains to be elucidated.

An update in recurrent spontaneous abortion

Recurrent spontaneous abortion (RSA) is defined as three or more consecutive pregnancy losses prior to the 20th week of gestation. The etiology of recurrent spontaneous abortion is often unclear and may be multifactorial, with much controversy regarding diagnosis and treatment. Reasonably accepted etiologic causes include, genetics, anatomical, endocrine, placental anomalies, hormonal problems, infection, smoking and alcohol consumption, exposure to environmental factors, psychological trauma and stressful life event, certain coagulation and immunoregulatory protein defects. Detection of an abnormality in any of these areas may result into specific therapeutic measures, with varying degrees of success. However, the majority of cases of RSA remains unexplained and is found to be associated with certain autoimmune (APA, ANA, ACA, ATA, AECA) and alloimmune (APCA, Ab2, MLR-Bf) antibodies that may play major role in the immunologic failure of pregnancy and may lead to abortion. Alteration in the expression of HLA-G molecules, T-helper-1 (Th-1) pattern of cytokines and natural killer (NK) cells activity may also induce abortion. Various forms of treatment like antithrombotic therapies such as aspirin and heparin, intravenous immunoglobulin (IVIg) therapy, immunotherapy with paternal lymphocytes and vitamin D3 therapy are effective mode of treatment for unexplained cause of fetal loss in women with RSA.

Lack of Histocompatibility Leukocyte Antigen-G expression in early embryos is not related to germinal defects or impairment of interleukin-10 production by embryos

The expression of Histocompatibility Leukocyte Antigen (HLA)-G molecules is a mandatory prerequisite for the development of pregnancy but no hypotheses have yet been advanced regarding the lack of HLA-G modulation expression in a percentage of early embryos obtained by in vitro fertilization (IVF). One possible hypothetical model assumes that the absence of regulation of HLA-G or impaired interleukin (IL)-10 secretion could be related to germinal defects. We investigated the presence of soluble HLA-G antigens in supernatants of single embryo cultures from couples admitted to a second fertilization procedure; these couples showed a complete absence of HLA-G modulation in the first cycle's embryo supernatants (0/31). The results obtained in the second IVF cycle showed embryo supernatants positive for HLA-G (14/40), suggesting that the previous lack of antigen modulation is independent of germinal defects. Furthermore, since it has been reported that oocytes and early embryos can secrete IL-10, an anti-inflammatory cytokine produced by type 2 helper T cells that induces upregulation of HLA-G expression in monocytes and trophoblasts, we investigated the levels of IL-10 and soluble HLA-G in 40 embryo culture supernatants from 21 IVF cycles. No associations were observed between the presence of IL-10 and the production and concentrations of soluble HLA-G, or between IL-10 levels and pregnancy outcome. These results indicate that the lack of HLA-G production in early embryos is not related to germinal defects or to impairment in embryo IL-10 secretion but could be ascribed to possible uncorrected fertilization processes.

Th2/Th3 cytokine genotypes are associated with pregnancy loss

Cytokines are critical immunoregulatory molecules, responsible for determining the nature of an immune response. It has been proposed that Th2/Th3 immune reactions support normal pregnancy, while Th1 immunity is considered detrimental to the fetus. Since cytokine production is partly under genetic control, it is possible that women suffering from a high incidence of abortions are genetically predisposed to mount a type of immune response inappropriate for pregnancy maintenance. This study investigated the frequencies of cytokine gene polymorphisms in abortion-prone women and women with successful pregnancies. We investigated the role of Th1/Th2/Th3 cytokine gene polymorphisms, such as TGF-beta1 codon 10 (TGFbetac10; C to T), TGF-beta1 codon 25 (TGFbetac25; G to C), TNFalpha promoter-308 (G to A), IL-6 promoter-174 (G to C), IL-10 promoter-1082 (G to A), IL-10 promoter-819 (C to T), IL-10 promoter-592 (C to A), and IFNgamma intron 1 +874 (A to T) in abortion-prone female patients. Our results support the importance of Th2/Th3 immune responses in pregnancy loss, and suggest that an individual's immunogenetic profile indicative of imbalances in Th2/Th3 cytokines is associated with pregnancy loss. Our results suggest that abortive events are determined by genetic factors, reflected in the female patient's immunogenetic profile.

High cord blood IL-10 levels in preterm newborns with respiratory distress syndrome

BACKGROUND

The development of respiratory distress syndrome (RDS) is closely related to fetal immaturity, although the participation of inflammatory mechanisms also seems to be likely. We previously reported high interleukin-10 (IL-10) levels in cord blood from preterm infants. In the present study, we investigate the possible role of IL-10 and IL-12 in preterm newborns with RDS, a disease that is also closely related to gestational age.

PATIENTS AND METHODS

Cord blood levels of IL-10 and IL-12 (p70 + p40) were determined by ELISA in 20 preterm infants who later developed RDS, in 21 preterm infants without RDS and in 31 full term newborns. In 11 patients follow-up samples could be also obtained between 2 and 14 days of life.

RESULTS

Preterm infants with RDS showed higher IL-10 (27 vs 10.8 pg/mL; p: 0.0003) and lower IL-12 (188 vs 384; p: 0.002) levels in cord blood than premature infants without RDS and full term newborns (IL-10: 3.2 pg/mL, p: 0.0001; IL-12: 352 pg/mL; p: 0.002). The differences remained statistically significant after correction for the effect of gestational age between both preterm groups.

CONCLUSIONS

The results obtained may be related to an immature cytokine response in premature infants, but the IL-12/IL-10 imbalance found in our patients also supports the hypothesis that inflammation plays a role in RDS.

Macrophages and apoptotic cell clearance during pregnancy

BACKGROUND

During implantation, apoptosis is critical for the appropriate tissue remodeling of the maternal decidua and invasion of the developing embryo, yet the regulation of apoptosis is also imperative for a successful pregnancy. The quick and effective removal of apoptotic cells by tissue macrophages represents an essential process, which prevents the release of self-antigens, and in the case of pregnancy, paternal alloantigens.

METHODS OF STUDY

Recent studies have shown that the process of apoptotic cell clearance is not a neutral event, but rather an active one that induces macrophage production of anti-inflammatory cytokines and survival factors. Apoptotic cell clearance is, therefore, necessary for the resolution of inflammatory conditions, which during pregnancy could have lethal consequences.

CONCLUSIONS

The function of the maternal immune system during implantation and throughout pregnancy is, therefore, an important area of investigation. This review will discuss the role of decidual macrophages in apoptotic cell clearance during pregnancy.

Cytokine secretion patterns of NK cells and macrophages in early human pregnancy decidua and blood: implications for suppressor macrophages in decidua

PROBLEM

Local immune modulation has been shown to be of considerable importance for the maintenance of successful pregnancy. We have previously reported the secretion of interferon-gamma (IFN-gamma), interleukin-4 (IL-4) and IL-10 in human decidua from early normal pregnancy. The aim of this study was to investigate the cellular source of cytokine secretion in the decidua, and compare this to secretion patterns in peripheral blood.

METHOD OF STUDY

Decidual tissue and peripheral blood was collected from 20 women undergoing surgical abortion during first trimester pregnancy. Monocytes/macrophages and NK cells were enriched by immunomagnetic cell separation and cytokine secretion was detected by enzyme-linked immunosorbent spot-forming cell assay.

RESULTS

Decidual and peripheral monocytes/macrophages and NK cells spontaneously secrete IFN-gamma, IL-4 and IL-10. The number of IL-10 secreting cells was significantly higher in decidual macrophages compared with decidual non-monocytic cells as well as compared with blood monocytes/macrophages. These differences were not seen for IFN-gamma or IL-4.

CONCLUSIONS

Our results indicate that decidual macrophages subserve important suppressive functions in the pregnant uterus.

Increased Expression of Pro-Inflammatory Cytokines in Placentas of Women Undergoing Spontaneous Preterm Delivery or Premature Rupture of Membranes

PROBLEM

The objective of this study was to determine the levels of cytokines in the placentas of women undergoing preterm delivery (PTD) or premature rupture of membranes (PROM) as compared with women undergoing normal delivery at term.

METHOD OF STUDY

Placentas were obtained from 30 subjects with spontaneous PTD, 30 women with PROM and 30 women with a history of normal delivery at term. Levels of interleukin (IL)-2, interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, TNF-beta, IL-4, IL-5, IL-6 and IL-10 and IL-12 were estimated by ELISA in detergent lysates of placentas from the subjects.

RESULTS

We found significantly increased levels of the Th1 cytokines IL-2 and IFN gamma and of the Th1-inducing cytokine IL-12 in placentas from the PTD and PROM groups as compared with those delivering at term. In contrast, the levels of the Th2 cytokines IL-4, IL-6 and IL-10 were significantly higher in placentas from term pregnancy.

CONCLUSIONS

These data support our observation of a pro-inflammatory cytokine bias in women with PTD and PROM.

Evaluation of Cytokeratin 7 as an accurate intracellular marker with which to assess the purity of human placental villous trophoblast cells by flow cytometry

Villous trophoblast cells (TC) obtained from first trimester and term human placentae after trypsin/Percoll gradient isolation were immunodepleted of contaminant cells. The level of purity was assessed by the intracellular expression of the pan trophoblast marker cytokeratin-7 (CK7) and comparisons were made with the GB25 trophoblast-specific (cytotrophoblast+syncytiotrophoblast) cell surface marker. The presence of contaminating cells was traced with intracellular vimentin, or cell surface CD2, CD36, and CD163 markers and evaluated by flow cytometric analysis. The pattern of CK7 expression by trophoblast cells was also analyzed by immunofluorescence microscopy. Most batches of TC from first trimester or term placentae (92+/-3% and 96+/-2%, respectively) showed a high percentage of CK7 expressing cells, with less than 2% contaminating vimentin positive cells. In some batches of TC with a lower percentage (65+/-4%) of CK7-expressing cells, no vimentin was found, but a low percentage of CD36-expressing cells was evidenced, with no presence of CD2, and/or CD163-expressing cells. The intracellular CK7 signal correlated significantly with that of GB25 (p<0.05) cell surface expression in TC of term placentae. The choriocarcinoma BeWo and Jar cell lines also showed high levels (>92%) of CK7-expressing cells. Conversely, the control U87 astrocytoma cell line showed a high percentage (>90%) of vimentin but no CK7-expressing cells. These results provide evidence that the mutually exclusive pattern of intracellular CK7/vimentin expression of human TC can be used for evaluation by flow cytometry of the purity of primary human trophoblast cells.

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

PROBLEM

The inflammatory-anti-inflammatory cytokine network is thought to play a critical role in regulated progression and termination of pregnancy. The aim of this study was to evaluate the effects of interferon (IFN)-gamma on the expression of Cyclooxygenase (COX)-2 and production of prostaglandin E(2) (PGE(2)) in the human placenta from term and preterm labor deliveries.

METHOD OF STUDY

Placental explant culture system was used. COX-2 expression was determined by complementary techniques of immunohistochemistry and Western blotting. Released IFN-gamma and PGE(2) by placental explants were measured by enzyme-linked immunosorbent assay. Signal transducer and activator of transcription 1 (STAT1) phosphorylation was evaluated by Western blotting using a specific antibody.

RESULTS

IFN-gamma was poorly detected in the placenta but was significantly expressed in decidual tissues from both term and preterm pregnancies as detected by immunohistochemistry. IFN-gamma significantly inhibited COX-2 expression and PGE(2) release in cultured placental explants from term and preterm labor deliveries. This effect most likely occurred in a STAT1-dependent manner as this regulatory protein was phosphorylated in response to IFN-gamma. IFN-gamma receptor (IFN-gammaR) was expressed in normal early pregnancy placental samples. However, its expression was significantly reduced in placental samples from term and preterm deliveries. Of interest, IFN-gammaR was expressed in placentas from term and preterm labor deliveries after 24 hr in culture.

CONCLUSIONS

Our data suggest that the human placenta is an important site for IFN-gamma-mediated repression of COX-2 expression and PGE2 production, implying that functional withdrawal of IFN-gamma may be involved in the onset of term or preterm labor.