An innate view of human pregnancy

Total sialic acid and associated elements of the metabolic syndrome in women with and without previous gestational diabetes

OBJECTIVE

Inflammatory markers predict type 2 diabetes and relate to the metabolic syndrome. Gestational diabetes mellitus (GDM) predicts type 2 diabetes and may be part of this syndrome. To examine the association of inflammatory markers with GDM, we investigated total sialic acid (TSA) in women with and without previous GDM.

RESEARCH DESIGN AND METHODS

All women with GDM and a random sample of women from one center of the Brazilian Study of Gestational Diabetes were invited to return 7 years after their index pregnancy. After an interview, an oral glucose tolerance test and anthropometry were performed. A total of 46 women with and 50 women without previous GDM completed the protocol.

RESULTS

Mean TSA was significantly higher in women with (71.8 +/- 11.1 mg/dl) than without (67.5 +/- 9.8 mg/dl) previous GDM (P < 0.05). In a linear regression model, TSA was 4 mg/dl (P < 0.05) higher in women with previous GDM, after adjustment for BMI, fasting insulin sensitivity, and number of years spent in school. In a similar model, current 2-h plasma glucose levels were associated with higher TSA levels after adjustment for waist-to-hip ratio and the log of triglycerides. TSA was strongly correlated with individual components and aggregates (r = 0.55, P < 0.001) of the metabolic syndrome.

CONCLUSIONS

Increased TSA levels are associated with previous GDM and are strongly linked to the metabolic syndrome. These findings in young women suggest that a chronic mild systemic inflammatory response is an early feature of the metabolic syndrome and that GDM may be a window for its investigation.

Accumulation of CD16+ cells with secretion of Ksp37 in decidua at the end of pregnancy

PROBLEM

Maternal cellular immunity is thought to be in a state of tolerance during pregnancy, but the precise mechanism of immunomodulation is not yet known. We investigated a novel serum protein, killer-specific secretory protein of 37 kDa (Ksp37), produced by cytotoxic lymphocytes, during pregnancy.

METHOD OF STUDY

The level of Ksp37 was determined by enzyme linked immunosorbent assay (ELISA) in the sera of healthy pregnant women. Intracellular Ksp37 expression in mononuclear cells, isolated from peripheral blood and decidua at parturition, was examined with a flow cytometer.

RESULTS

Serum Ksp37 levels significantly increased at late pregnancy, compared with non-pregnant controls and the first trimester of pregnancy. The flow cytometric analysis exhibited that Ksp37 was mainly expressed in CD16+ natural killer (NK) cells in decidua of term placenta.

CONCLUSIONS

Serum Ksp37 level was elevated at late gestational period. CD16+ NK cells in decidua seem to be a main maternal source of Ksp37. Innate immunity, with CD16+ NK cells, may play important roles near parturition.

Expression of intercellular adhesion molecule-1 on the surface of peripheral blood and decidual lymphocytes of women with pregnancy-induced hypertension

OBJECTIVE

If overexpression of intercellular adhesion molecule-1 (CD54) on lymphocytes exists it could have important implications for the pathophysiology of pregnancy-induced hypertension (PIH).

STUDY DESIGN

CD54 "in vitro" expression (described as (%) of CD54+cells and CD54 mean fluorescence intensity, MFI) on the peripheral blood and decidual lymphocytes of pregnant with pre-eclampsia (PE) (n=16), transient hypertension (TH) (n=12), and controls (n=9).

RESULTS

The percent (%) of CD54+peripheral blood lymphocytes, CD54 MFI on them and CD54 MFI on decidual lymphocytes were increased especially in PE. During PE the (%) of CD54 decidual lymphocytes correlated negatively with platelet count. In TH the positive correlation between the blood pressure and the (%) of CD54 peripheral blood lymphocytes as well as CD54 MFI on decidual lymphocytes were found.

CONCLUSIONS

(1) PIH, especially PE, is accompanied by overexpression of intercellular adhesion molecule-1 (ICAM-1) on peripheral blood and decidual lymphocytes studied "in vitro", (2) Some of the parameters studied seem to correlate with clinical markers of PIH intensity but this fact needs further investigations using larger subject groups.

Cytokine secretion by decidual lymphocytes in transient hypertension of pregnancy and pre-eclampsia

BACKGROUND

Transient hypertension (TH) and preeclampsia (PE) are believed to have different pathophysiology. However, 15-25% of pregnant women initially diagnosed as having TH develop PE. To clarify the immuno-pathogenetical connections between the two syndromes, we studied the pattern of T helper cell (Th)1/Th2 cytokine balance disturbances existing inside maternal decidua in normal pregnancy (NP) and pregnancies complicated with TH and PE.

METHODS

Third-trimester decidual tissue was obtained by curettage of uterine cavity during elective caesarean sections in NP (n = 11), TH (n = 17) and PE (n = 21) patients. Cell suspensions were prepared by an electromechanical dispersal method and centrifugated using a standard gradient sedimentation technique. Isolated lymphocytes were placed in medium (RPMI 1640, 10% fetal calf serum, L-glutamine, penicillin, streptomycin) and cultured for 72 h with or without mitogen phytohaemaglutinine (PHA). The enzyme-linked immunosorbent assay method was used for estimation of interleukin (IL)-2, IL-4, IL-6, IL-10, IL-12 and interferon-gamma (IFN-gamma) in culture supernatant.

STATISTICAL ANALYSIS

The Kruskal-Wallis and the Mann-Whitney U tests were used (p < 0.05).

RESULTS

Both spontaneous and PHA-stimulated secretion of Th2-type cytokines IL-6 and IL-10 was decreased in PE patients compared with TH and NP patients. The concentration of Th1-type cytokine IFN-gamma was increased in patients suffering both from TH and PE.

CONCLUSION

On the base of decidual cytokine secretion, both PE and TH are syndromes of local Th1/Th2 cytokine balance disturbances as compared with NP, and TH seems to be an intermediate step to PE.

Cytokine expression in peripheral blood lymphocytes indicates a switch to T(HELPER) cells in patients with preeclampsia

We sought to determine whether cytokine expression in peripheral blood mononuclear cells is altered in patients with preeclampsia and in patients with a history of recurrent spontaneous abortion (RSA). Twenty-four patients with preeclampsia and twenty patients with a history of RSA were included into the study. Two control groups consisted of twenty healthy pregnant and twenty healthy non-pregnant women. The intracellular expression of interleukin-2 (IL-2), interleukin-4 (IL-4) and interferon-gamma (IFN-gamma) were determined in peripheral blood mononuclear cells (PBMCs) by flow cytometry as a measure of cytokine production. IL-2 synthesis was significantly elevated in the third trimester in preeclamptic patients in comparison with the control group. Non-pregnant women with RSA showed a significantly lower expression of IFN-gamma compared to the non-pregnant control group. Our data suggest an abnormal immune response in preeclamptic patients characterised by a shift to a predominantly Th1-type immunity.

Alterations in the expression of homing-associated molecules at the maternal/fetal interface during the course of pregnancy

One of the most fascinating immunologic questions is how the genetically distinct fetus is able to survive and develop within the mother without provoking an immune rejection response. The pregnant uterus undergoes rapid morphological and functional changes, and these changes may influence the nature of local immune responses at the maternal/fetal interface at different stages of gestation. We hypothesized that specialized mechanisms exist to control access of maternal leukocyte subsets to the decidua and that these mechanisms are modulated during the course of pregnancy. At the critical period of initial placenta development, the maternal/fetal interface displays an unparalleled compartmentalization of microenvironmental domains associated with highly differentiated vessels expressing vascular addressins in nonoverlapping patterns and with recruitment of specialized leukocyte subsets (monocytes, granulated metrial gland cells, and granulocytes) thought to support, modulate, and regulate trophoblast invasion. One of the most striking observations at this time of gestation is the almost complete exclusion of lymphocytes from the maternal/fetal interface. The second half of pregnancy is characterized by a partial loss of microenvironmental specialization and different switches in vascular specificity within the decidua basalis, paralleling dramatic changes in the populations of recruited leukocytes (e.g., a striking influx of lymphocytes, especially T cells). In the term pregnant uterus, the expression of all vascular addressins decreased dramatically; only weakly staining maternal vascular segments remained. These segments may define sites of extremely low residual traffic in the term decidua, which contains remarkably few maternal leukocytes overall. Our results suggest that the maternal/fetal interface represents a situation in which leukocyte trafficking is exquisitely regulated to allow entry of specialized leukocyte subsets that may play a fundamental role in immune regulation during pregnancy.

Immune regulation during pregnancy and host-pathogen interactions in infectious abortion

The immunological mechanisms that govern the success of pregnancy in outbred mammals are complex. During placental formation the invasion of fetal cells into maternal tissue must be controlled to prevent damage to the mother. Equally, maternal recognition of pregnancy must be such that allorejection of the fetus does not occur. Despite the complexity of this phenomenon, it is clear that cytokines play a crucial role at the maternofetal interface and in the periphery to ensure that pregnancy proceeds successfully. Inflammatory cytokines such as tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) can exert detrimental effects in the placenta and tend to be present at low concentrations, whereas the regulatory cytokines interleukin (IL)-10 and tranforming growth factor-beta (TGF-beta) are beneficial and tend to predominate. This means that infection with pathogens that target the placenta and that elicit inflammatory responses may cause abortion by giving rise to a detrimental combination of cytokines that causes damage but does not control the disease. Infectious abortion is discussed in the context of the modulation of host immune responses during pregnancy, taking into account the different placental structures present in human beings, rodents and ruminants.

Normal pregnancy is associated with peripheral leukocyte activation

PROBLEM

Normal pregnancy has been described as both a pro-inflammatory condition and a T helper (Th)2-dominated state. Deviations in the percentage of different subpopulations of circulating leukocytes have been detected, although with conflicting results. This study was designed to analyse further the phenotype of subpopulations of peripheral blood leukocytes in normal pregnant women.

METHOD OF STUDY

Whole-blood flow cytometry was used to differentiate subsets of leukocytes using directly labeled monoclonal antibodies to specific cell surface antigens and to a panel of activation-associated markers in 33 normal pregnant women in their third trimester and in 26 non-pregnant controls.

RESULTS

We found a significant increase in the proportion of granulocytes and of CD8+ T lymphocytes during pregnancy. Up-regulation of the expression of adhesion molecules was observed on granulocytes, monocytes and T lymphocytes.

CONCLUSIONS

Pregnancy alters the representation of leukocyte subpopulations in the maternal circulation and is associated with systemic activation of leukocytes.

Vertical transmission of Schistosoma japonicum in the rabbit

The aim of the present study was to confirm observations on the vertical transmission of Schistosoma japonicum in the rabbit. S. japonicum-infected pregnant rabbits were used in this study. Perfusion of mother rabbits was done 9 weeks after infection in order to obtain worm burdens in relation to their initial cercarial dose. Anti-schistosoma specific IgM antibodies in serum samples collected from rabbit kittens were detected by ELISA. Our results showed that gestation period lasted the normal 29-31 days. All the exposed mother rabbits became infected with S. japonicum. Positive IgM antibody OD values were detected in 12 out of the 60 kittens examined (20.0%). In group C and A, 40.0% and 17.9% of the kitten were congenitally infected, respectively. 18.1% of the kittens born to mothers infected with a single dose of 200 cercariae per rabbit were positives; this is not significantly different from that obtained for the 600 dose group (22.2%). Three randomly selected IgM+ kittens harbored between one and two adult worms. The livers of these kittens displayed granulomatous lesions. It is concluded that congenital S. japonicum infection does occur in the rabbit and is affected by the mother stage of pregnancy and to a lesser extent by its infection load.

Inhibition of septic shock in mice by an oligopeptide from the beta-chain of human chorionic gonadotrophin hormone

Human chorionic gonadotrophin (hCG) is a heterodimeric placental glycoprotein hormone required in pregnancy. In human pregnancy urine and in commercial hCG preparations (c-hCG) it occurs in a variety of forms, including breakdown products. Several reports have suggested modulation of the immune system by intact hormone, but such effects of breakdown products have not been reported. In a related article (Hum Immunol 62:1315, 2001), it is reported that a 400-2000 Dalton (Da) fraction from c-hCG and from human pregnancy urine inhibits Th1-mediated diabetes in NOD mice. The active component(s) were called natural (immuno)modulatory pregnancy factor(s) (NMPF). This study reports that a single treatment with the same low molecular weight NMPF fraction up to 24-h after high dose lipopolysaccharide (LPS) injection inhibited septic shock in mice. This counteracting effect of NMPF paralleled the downregulation of the effects of LPS on the production of macrophage migration inhibitory factor (MIF) by spleen cells, on the plasma level of liver aminotransferase, and on the expression of several splenic lymphocyte and macrophage surface markers. Based on the primary structure of the beta-chain of hCG a synthetic hexapeptide Valine-Leucin-Proline-Alanine-Leucine-Proline (VLPALP) was designed, which demonstrated it to have the same protective effects as the 400-2000 Da NMPF fraction. These results indicate a new strategy for the treatment of septic shock and the potential of therapeutic use of this synthetic oligopeptide.

Phenotypic and metabolic characteristics of monocytes and granulocytes in normal pregnancy and maternal infection

OBJECTIVE

Normal pregnancy has been proposed to be a state of physiologic activation of the innate limb of the immune response. Recent studies have concluded that normal pregnancy produces inflammatory changes in peripheral blood leukocytes akin to those of sepsis. This unexpected observation has implications that are critical to understanding the susceptibility of pregnant women to sepsis, the pathophysiology of preeclampsia, and the biology of normal pregnancy. This study was designed to examine the phenotypic and metabolic characteristics of monocytes and granulocytes in normal pregnancy and in pregnant patients with acute infection.

STUDY DESIGN

A cross-sectional study was conducted that included nonpregnant women (n = 20), normal pregnant women (n = 57), and pregnant women with a positive blood culture and/or pyelonephritis (n = 16). Phenotypic and metabolic characteristics of monocytes and granulocytes were studied with the use of flow cytometry and monoclonal antibodies against surface markers (CD11b, CD14, CD15, CD16, CD18, CD49d, CD62L, CD64, CD66b, and HLA-DR). Intracellular reactive oxygen species were measured at basal conditions and after stimulation (oxidative burst). The stimulation index (ratio of intracellular reactive oxygen species after oxidative burst over basal state) was calculated. Nonparametric statistics were used. A probability value of <.01 was considered statistically significant.

RESULTS

Granulocytes from normal pregnant women had a higher median mean channel brightness for CD14 and CD64, but lower median mean channel brightness for CD16 and HLA-DR than granulocytes of nonpregnant women. Granulocytes of patients with acute infection had a higher median mean channel brightness for CD64 and CD66b than granulocytes of normal pregnant women. Monocytes from patients with acute infection had a higher mean channel brightness for CD11b, CD16, CD18, CD49d, CD64, and CD66b than monocytes of normal pregnant women. Baseline intracellular reactive oxygen species, oxidative burst, and stimulation index values were significantly higher in the granulocytes and monocytes of normal pregnant women than in the granulocytes and monocytes of nonpregnant women. Similarly, baseline intracellular reactive oxygen species, oxidative burst, and stimulation index values were higher in women with acute infections than in normal pregnant women.

CONCLUSION

Normal pregnancy was associated with phenotypic and metabolic changes of granulocytes and monocytes; pregnant women with acute infection had more marked phenotypic and metabolic changes of leukocytes than normal pregnant women. These qualitative differences indicate that the innate limb of the immune response is not maximally activated during normal pregnancy.

Why isn't the fetus rejected?

The long-standing question of how the fetal allograft avoids immune rejection during pregnancy has lately been generating renewed interest. Recent insights have emerged from studies in mice on uterine NK cells, NKT cells, complement inhibition and the reproductive effects of 1-methyl-tryptophan.

Phenotypic and metabolic characteristics of monocytes and granulocytes in preeclampsia

OBJECTIVE

The maternal syndrome of preeclampsia has recently been attributed to a systemic intravascular inflammatory response and endothelial cell activation and dysfunction. This novel hypothesis has considerable clinical and biological implications. This study was designed to determine whether women with preeclampsia have evidence of intravascular inflammation by examination of the phenotypic and metabolic activity of granulocytes and monocytes.

STUDY DESIGN

A cross-sectional study was performed that included patients with preeclampsia (n = 31) and normal pregnancies (n = 58) matched for gestational age at blood draw. Intravascular inflammation was studied with use of flow cytometry. Peripheral venous blood was assayed to determine granulocyte and monocyte phenotype with the use of monoclonal antibodies for selective cluster differentiation (CD) antigens. The panel of antibodies included CD11b, CD14, CD16, CD18, CD49d, CD62L, CD64, CD66b, and HLA-DR. The quantity of basal intracellular reactive oxygen species and oxidative burst was assessed. Results were reported as mean channel brightness or intensity of detected fluorescence. Analysis was conducted with nonparametric statistics. A P value <.01 was considered to be significant.

RESULTS

Preeclampsia was associated with a significant increase in mean channel brightness for CD11b on granulocytes and monocytes but lower mean channel brightness for CD62L on granulocytes than those from women with normal pregnancy (P <.01 for each). Basal intracellular reactive oxygen species were increased in monocytes but not in granulocytes. The oxidative burst was higher in both cell types.

CONCLUSION

Preeclampsia is associated with phenotypic and metabolic changes in granulocytes and monocytes.

Preeclampsia, a pregnancy-specific disease, is associated with fetal monocyte activation

The maternal syndrome of preeclampsia is an exclusively pregnancy-related illness involving multiple organs and severe forms may be complicated by HELLP (hemolysis, elevated liver enzymes, low platelets) syndrome. Recently, it has been proposed that both normal pregnancy and preeclampsia are associated with a systemic activation of the nonspecific maternal immune system and that, in particular, monocytes have a central role in the adjustment of maternal immune functions in pregnancy. Here we have investigated the role of the fetal nonadaptive immune system in normal term delivery, uncontrollable preterm labor, and preeclampsia. We demonstrate that spontaneous delivery at term as well as preterm occurrence of preeclampsia or HELLP syndrome are accompanied by an increased intracellular production of IL-6 in fetal monocytes, indicating strong activation of this cell type. In contrast, we show that elective cesarean delivery at term in the absence of labor or preterm delivery due to uncontrollable labor are not accompanied by an increased production of IL-6 in these cells. These results suggest that increased IL-6 synthesis in fetal monocytes may be a process occurring in association with normal spontaneous term delivery and that this process obviously occurs in early pregnancy in case of preeclampsia. Therefore, we propose that the activation of fetal monocytes as effectors of the innate immunity may be involved in mechanisms inducing spontaneous term delivery and that the occurrence of preeclampsia may be based on dysfunctions of probably both the maternal and the fetal innate immune system.

Interleukin-18 in human milk

We analyzed IL-18 levels of human milk. Colostrum contained significantly higher levels of IL-18 compared with early milk and mature milk. By stepwise multiple linear regression analysis, preterm delivery and pregnancy complications of mothers significantly correlated with high levels of IL-18 in human milk (p = 0.0007 and 0.0018, respectively). There was a significant correlation between the levels of IL-18 and soluble Fas ligand in colostrum (p = 0.0003). IL-18 was detected in actively secreting epithelial cells in lactating mammary gland by immunohistochemical staining. These results suggest that IL-18 in colostrum plays an important role in host defense of high-risk neonates.

The effect of Ureaplasma diversum activated mononuclear leukocytes on the development and interferon-tau production by bovine IVF-derived embryos

Ureaplasma diversum is an opportunistic pathogen of the bovine genital tract causing herd outbreaks of granular vulvitis, abortion and infertility. Early embryonic death probably contributes to reduction of the reproductive performance in cows, however, pathogenesis of the disease remains obscure. The aim of the study was to examine whether activation of mononuclear leukocytes by U. diversum may affect embryo development and IFN-tau production. Bovine peripheral blood mononuclear leukocytes were cultured with U.diversum antigen for 24 h. The levels of IL-1, TNF-alpha, NO and GM-CSF in the cell culture supernatants were measured. IVF-derived embryos were cultured in the presence of supernatants from activated leukocytes. The development of embryos until day 6 postinsemination and the rate of morulae/blastocysts were determined. IFN-tau production in supernatants of cultured embryos was examined by inhibition of a virally-induced cytopathic effect. The results showed that U. diversum stimulated mononuclear leukocyte production of IL-1, TNF-alpha and NO. Supernatants from U. diversum-activated cells did not impair the rates of the embryo development and blastocyst formation. The products of activated leukocytes increased the IFN-tau production by cultured blastocysts. This suggest that U. diversum infection provides leukocyte-mediated signals for developing embryos for generation of additional production of cytokine - an important component of innate immunity.

Coeliac disease in the father affects the newborn

BACKGROUND AND AIMS

Untreated coeliac disease in the mother is associated with lower birth weight. We examined the risk of adverse neonatal outcome when the infant's mother, father, or other relative suffered from known coeliac disease.

METHODS

Mothers answered a questionnaire a few days after the birth of their infant. Of a total of 10,597 single birth infants from Southeast Sweden, 53 infants had a mother with coeliac disease (father 27, sibling 70, other close relative 442). Adjusted odds ratios and adjusted differences for neonatal outcome were calculated.

RESULTS

Infants whose father suffered from coeliac disease had a lower birth weight (95% adjusted confidence interval (CI) -459, -72 g), more often belonged to the low birth weight (LBW) category (LBW < or =2499 g) (95% CI adjusted odds ratio (AOR) 1.48--17.18), and had a shorter pregnancy duration (95% adjusted CI -1.53, -0.08 weeks) than non-coeliac controls. They also weighed less than infants whose father suffered from other autoimmune diseases (95% CI -549, -93 g). Infants whose mother suffered from coeliac disease had a lower birth weight (95% adjusted CI -370, -74 g) and more often belonged to the LBW category (95% CI AOR 2.60--15.08) than non-coeliac controls. These infants were more often in the LBW category than infants whose mother suffered from non-diabetic autoimmune diseases (95% CI AOR 1.24--9.65). Coeliac disease in other relatives was not associated with any adverse effect on neonatal outcome.

CONCLUSIONS

This study suggests that even treated coeliac disease, in either of the parents, has a negative effect on pregnancy, resulting in lower birth weight and perhaps shorter duration of pregnancy.

Cytokine promoter gene polymorphisms and idiopathic recurrent pregnancy loss

Approximately one in 300 women experience recurrent pregnancy loss (RPL), the aetiology of which is unknown in at least 40% of cases. Previously, some studies have shown increased production of pro-inflammatory cytokines (tumour necrosis factor-alpha and interferon-gamma) and reduced production of anti-inflammatory cytokines (interleukin-10) by circulating blood lymphocytes isolated from these patients when compared with controls. The reasons for this are unclear. The production of these cytokines are partly under genetic control. This study investigated whether polymorphisms in these three cytokine genes known to be associated with either high or low production, are associated with idiopathic RPL. No association was found. It may be that genetic factors are not a major determinant of cytokine production during pregnancy, or alternatively it may be that the observed differences in cytokine production by peripheral lymphocytes do not accurately indicate what is occurring at the local maternofoetal interface during successful and abortive pregnancies.

[HLA molecules, immunity and gestation]

During pregnancy, the fetus develops particularly efficient molecular regulatory mechanisms to prevent possible maternal anti-paternal alloimmune response and avoid viral spreading from maternal tissue. Among the different mechanisms, there has been noted a selective expression of HLA molecules on trophoblast cells: the absence of HLA class II and of polymorphic HLA-A and HLA-B expression but presence of both non polymorphic HLA-G and HLA-E class Ib as well as of HLA-C class Ia. The functional consequences of such a particular pattern of HLA expression in gestation are examined here.

Gestational attenuation of Lyme arthritis is mediated by progesterone and IL-4

Infection of different strains of laboratory mice with the agent of Lyme disease, Borrelia burgdorferi, results in arthritis, the severity of which has been correlated with the dominance of Th1 cytokines. In this study, we demonstrate that changes in B. burgdorferi-specific immunologic responses associated with pregnancy can alter the outcome of Lyme arthritis in mice. Whereas nonpregnant female C3H mice consistently developed severe Lyme arthritis, pregnant mice had a marked reduction in arthritis severity that was associated with a slight reduction in IFN-gamma and markedly increased levels of IL-4 production by B. burgdorferi-specific T cells. Similar reductions in arthritis severity and patterns of cytokine production were observed in nonpregnant, progesterone-implanted mice. Ab neutralization of IL-4 in progesterone-implanted mice resulted in severe arthritis. Our results are consistent with the known shift toward Th2 cytokine expression at the maternal-fetal interface, and are the first to show a pregnancy-related therapeutic effect in an infectious model.

Human natural chimerism: an acquired character or a vestige of evolution?

Analysis on five common classes of human natural chimeras (cytomictical, whole body, fetal-maternal, germ cell, and tumor chimeras) reveals that (1) they initiate only during pregnancy, (2) the most common class are chimeras which contain maternal cells, and (3) the primary mechanisms that are involved in their formation and establishment are still elusive. These classes of natural chimerism, are involved only with maladaptive phenomena such as malignancy and autoimmune diseases and without any documented benefit. A recent review has challenged the accepted dogma that the evolution of immunity is pathogen-directed and asserted that preserving individuality from littering the soma and the germline by conspecific alien cells might have been the original function of the innate immunity. Following this tenet, I propose here that human natural chimerism is a by-product of the new role evolved from primitive components of immunity to "educate" the developing embryo with the armamentarium of effector mechanisms, dedicated to purge the individual from pervasive somatic and germline variants, and is not a vestige of evolution.

Is antigen presentation the primary function of HLA-G?

Human histocompatibility leukocyte antigen (HLA)-G is an antigen-presenting molecule. This review discusses the possibility that this might not be its primary function. HLA-G indeed modulates innate immunity by interacting with immunoglobulin-like receptors and by regulating HLA-E expression and its subsequent interaction with CD94/NKG2 receptors. HLA-G also down-modulates both CD8(+) and CD4(+) T-cell responsiveness.

The pathogenesis of pre-eclampsia: new aspects

The etiology of pre-eclampsia, a disorder specific to pregnancy, has not yet been clearly established. Generalized endothelial dysfunction is thought to occur. Inadequate trophoblast invasion at the feto-maternal junction has also been postulated as the cause. However, recent findings are more suggestive of an inappropriate maternal inflammatory response within the framework of placentation, the innate immune system being primarily involved. This exaggerated maternal intravascular inflammatory reaction to the invading trophoblast leads to the manifestations of pre-eclampsia in the mother and feto-placental unit. The extent of the inflammatory reaction, which is also present in normal pregnancy, is probably determined by genetic factors and any pre-existing disorder affecting the mother or fetus. The process is very complex and cannot be attributed to any one single cause.

Participation of the novel cytokine interleukin 18 in the host response to intra-amniotic infection

OBJECTIVE

Interleukin 18 is a proinflammatory pleiotropic cytokine that has been implicated in the host defense against infection. This study was undertaken to determine whether interleukin 18 concentrations change in the maternal, fetal, and amniotic fluid compartments with labor (term and preterm) and microbial invasion of the amniotic cavity.

STUDY DESIGN

Amniotic fluid was assayed for interleukin 18 in samples obtained from 285 patients in the following groups: (1) term not in labor (n = 22), in labor (n = 19), and with microbial invasion of the amniotic cavity (n = 16); (2) preterm labor who delivered at term (n = 38), who delivered preterm but without microbial invasion of the amniotic cavity (n = 41), and preterm labor with microbial invasion of the amniotic cavity (n = 24); (3) preterm premature rupture of membranes without microbial invasion of the amniotic cavity (n = 30) and with microbial invasion of the amniotic cavity (n = 34); (4) term premature rupture of membranes not in labor (n = 20) and term premature rupture of membranes in labor (n = 19); and (5) midtrimester (n = 22). In addition, cord and maternal plasma samples from women at term not in labor (n = 20) and in labor (n = 20) were assayed for interleukin 18.

RESULTS

(1) Interleukin 18 was detectable in all amniotic fluid samples and maternal and umbilical cord blood samples. (2) Interleukin 18 concentrations increased with advancing gestational age (r = 0.47; P <.0001). (3) Microbial invasion of the amniotic cavity in either preterm or term parturition was associated with a significant increase in the amniotic fluid concentration of interleukin 18 (preterm labor without microbial invasion of the amniotic cavity: median, 14.95 pg/mL; range, 3.9-277.0 pg/mL; vs preterm labor with microbial invasion of the amniotic cavity: median, 20.75 pg/mL; range, 5.53-160.21 pg/mL; P <.02; term labor without microbial invasion of the amniotic cavity: median, 18.73 pg/mL; range, 5.09-95.44 pg/mL; vs term labor with microbial invasion of the amniotic cavity: median, 24.35 pg/mL; range, 10.07-144.42 pg/mL; P<.004). (4) Both term and preterm parturition were associated with a modest increase in amniotic fluid interleukin 18 concentrations, although this trend did not reach statistical significance. (5) Rupture of membranes at term was associated with a significant decrease in amniotic fluid interleukin 18 concentrations (intact membranes: median, 14.96 pg/mL; range, <3.89-26.07 pg/mL; vs rupture of membranes: median, 10.1 pg/mL; range, 4.29-21.44 pg/mL; P <.001).

CONCLUSION

(1) Interleukin 18 is increased in cases of microbial invasion of the amniotic cavity. (2) Interleukin 18 is detectable in the amniotic, maternal, and fetal compartments. (3) We propose that this novel cytokine plays a role in the host defense against infection.

The expression of a novel natural killer inhibitory molecule, Cho-1, on the chorionic cytotrophoblast cells of successful pregnancy, but not of spontaneous abortion

The regulatory mechanism of the recognition and cytotoxicity by natural killer (NK) cells in placental tissue remains unclarified. Previous reports indicated that monoclonal antibody Cho-1-defined molecule (Cho-1 molecule) may act as the negative regulator in the cytotoxicity by human NK cells. The Cho-1 molecule is composed of non-covalently associated cell surface molecules of approximately 200 kDa and 40 kDa. In the present study we analyzed the expression of this novel molecule in extravillous cytotrophoblast cells, which are presumed to be exposed to the cytotoxic action by maternal NK cells, from clinical cases of successful pregnancy and spontaneous abortion. By using monoclonal antibody Cho-1, our immunohistochemical data indicated that the Cho-1 molecule is clearly expressed in the cytotrophoblast cells of the early phase of successful pregnancy, but only weakly expressed in those from spontaneous abortion. The cytotrophoblast cells in the late phase (9-10 months) of pregnancy also expressed this molecule. Fluorescence-activated cell sorter analysis also showed that it is expressed on the cytotrophoblast cell surface of successful pregnancy but not on that of spontaneous abortion, suggesting that Cho-1 antigen may act as a negative regulator of the cytotoxicity by NK cells in successful pregnancy of the fetus.

The Th2 cytokine environment of the placenta

It is now accepted that local changes to the balance of Th1/Th2-type cytokines occur during pregnancy within the maternal uterus and fetoplacental unit. These changes in cytokine profiles contribute to implantation of the embryo, development of the placenta, and survival of the fetus to term. Overall within the placenta there is a bias in the ratio of Th1:Th2 cytokines towards the Th2-type cytokines. However, there are specific fluctuations in this balance at implantation and during the initiation of parturition. The predominant cytokines at each stage of gestation function both to limit maternal immune rejection of the semi-allogeneic embryo/fetus, especially at the maternofetal interface; and to facilitate the on-going physiological processes within the maternal reproductive tract. These two, at times conflicting, roles are discussed in this review, with key evidence concerning cytokine expression and function from mouse and humans.

Trophoblast cell-specific carcinoembryonic antigen cell adhesion molecule 9 is not required for placental development or a positive outcome of allotypic pregnancies

The carcinoembryonic antigen (CEA) family consists of a large group of evolutionarily divergent glycoproteins. The secreted pregnancy-specific glycoproteins constitute a subgroup within the CEA family. They are predominantly expressed in trophoblast cells throughout placental development and are essential for a positive outcome of pregnancy, possibly by protecting the semiallotypic fetus from the maternal immune system. The murine CEA gene family member CEA cell adhesion molecule 9 (Ceacam9) also exhibits a trophoblast-specific expression pattern. However, its mRNA is found only in certain populations of trophoblast giant cells during early stages of placental development. It is exceptionally well conserved in the rat (over 90% identity on the amino acid level) but is absent from humans. To determine its role during murine development, Ceacam9 was inactivated by homologous recombination. Ceacam9(-/-) mice on both BALB/c and 129/Sv backgrounds developed indistinguishably from heterozygous or wild-type littermates with respect to sex ratio, weight gain, and fertility. Furthermore, the placental morphology and the expression pattern of trophoblast marker genes in the placentae of Ceacam9(-/-) females exhibited no differences. Both backcross analyses and transfer of BALB/c Ceacam9(-/-) blastocysts into pseudopregnant C57BL/6 foster mothers indicated that Ceacam9 is not needed for the protection of the embryo in a semiallogeneic or allogeneic situation. Taken together, Ceacam9 is dispensable for murine placental and embryonic development despite being highly conserved within rodents.

Maternal Trypanosoma cruzi infection upregulates capacity of uninfected neonate cells To produce pro- and anti-inflammatory cytokines

The possibility of maternal in utero modulation of the innate and/or adaptive immune responses of uninfected newborns from Trypanosoma cruzi-infected mothers was investigated by studying the capacity of their whole blood cells to produce cytokines in response to T. cruzi lysate or lipopolysaccharide-plus-phytohemagglutinin (LPS-PHA) stimulation. Cells of such newborns occasionally released gamma interferon (IFN-gamma) and no interleukin-2 (IL-2) and IL-4 upon specific stimulation, while their mothers responded by the production of IFN-gamma, IL-2, and IL-4. Infection in mothers was also associated with a hyperactivation of maternal cells and also, strikingly, of cells of their uninfected neonates, since their release of proinflammatory (IL-1beta, IL-6, and tumor necrosis factor alpha [TNF-alpha]) as well as of anti-inflammatory (IL-10 and soluble TNF receptor) cytokines or factors was upregulated in the presence of LPS-PHA and/or parasite lysate. These results show that T. cruzi infection in mothers induces profound perturbations in the cytokine response of their uninfected neonates. Such maternal influence on neonatal innate immunity might contribute to limit the occurrence and severity of congenital infection.

Thyroid disease in relation to pregnancy: a decade of change

Inspection of the references cited in this review indicates that much work has occurred in the area of thyroid and pregnancy during the last decade. Significant advances in our understanding of the immunology of pregnancy and the effect of thyroid disease on this process have taken place. The role of hCG in the physiology of pregnancy and its relevance to thyroid function has been an emerging theme. There is still no clear explanation for the association between thyroid antibodies and infertility or miscarriage. During the last decade a general concensus has developed in relation to the management of hyperthyroidism in pregnancy although there are still variations in antithyroid drug use at this time. The aetiological classification of congenital hyper- and hypothyroidism utilizing new technologies has opened up a new perspective on these disorders. Attention has been drawn to the importance of treating maternal hypothyroidism with adequate thyroid replacement therapy and to the possibility of impaired child neuropsychological development consequent on low maternal thyroid hormone concentration in early gestation in non iodine deficient areas. Significant advances have been made during the last decade in the description of the clinical features and in our understanding of the pathogenesis of postpartum thyroid disease. The importance of long-term follow up of selected patient groups has also been emphasized.

Prenatal immune priming with helminth infections: parasite-specific cellular reactivity and Th1 and Th2 cytokine responses in neonates

The present investigation aimed to determine to what extent maternal helminth infection primes parasite-specific cellular responsiveness in neonates. Umbilical cord mononuclear blood cells (UCBC) and peripheral blood mononuclear cells (PBMC) from mothers proliferated in response to mitogenic stimulation with concanavalin A, as well as to bacterial Streptococcus pyogenes-derived (streptolysin O) and helminth-specific antigens of Necator americanus and Onchocerca volvulus. Cellular responses to Echinococcus multilocularis (Em) and Oesophagostomum bifurcum (Oes), helminth parasites not endemic in the study area, were absent (for Em) or very low (for Oes due to antigenic cross-reactivity). Cellular responsiveness to mitogen and antigens was higher in mothers than in their neonates. Several Th1-type (IL-2, IL-12, and IFN-gamma) and Th2-type (IL-5 and IL-10) cytokines were produced by UCBC from neonates and PBMC from mothers. Low levels of IFN-gamma were elicited by UCBC in response to helminth and bacterial antigens, while secretion of IL-2 was pronounced and similarly high in neonates and their mothers. Amounts of IL-5 produced by UCBC in response to bacterial SL-O and mitogenic stimulation (PHA) were low, but equivalent levels of IL-5 were induced by intestinal helminth and filaria-derived antigens in neonates and mothers. A pronounced production of IL-10 and IL-12 by UCBC was observed--spontaneous IL-10 and IL-12 secretion by UCBC was higher in neonates than by PBMC from mothers. Net amounts of IL-10 elicited by helminth antigens were similar, while net IL-12 in response to mitogen, and bacterial and helminth antigens was significantly higher in mothers than their offspring. Our results indicate that human maternal helminth infection does sensitize in utero for parasite-specific cellular responsiveness in offspring, and also activates specific production of several cytokines, and such children do not present a dominant expression of immunity of either Th1 or Th2.

Induction of functional CD154 (CD40 ligand) in neonatal T cells by cAMP-elevating agents

A deficiency of neonatal T lymphocytes to express CD154 antigen in response to ionomycin and phorbol 12-myrsistate 13-acetate (PMA) stimulation or after CD3 cross-linking has been described. In the present report we describe that CD45RA+ newborn cells are able to synthesize and express CD154 at similar or even higher levels than adult cells in response to ionomycin and cAMP-elevating agents which trigger the protein kinase A (PKA) -mediated metabolic pathway. Peak CD154 protein concentrations in newborn cells were found between 4 and 8 hr after stimulation with ionomycin and dibutyryl cAMP. These agents, however, did not induce expression of the early activation antigen CD69. Surface levels of CD154 did not correlate with specific mRNA concentration, indicating that dibutyryl cAMP up-regulates CD154 by acting at a post-transcriptional stage. The CD154 antigen induced by PKA activation of newborn cells was functional, since upon binding to CD40 on B lymphocytes in the presence of interleukin-4 (IL-4), it promoted immunoglobulin heavy-class switching to IgE. We also found a different pattern of cytokine production between neonatal and adult CD4+ T cells. In response to ionomycin and dibutyryl cAMP, cord blood cells were more prone than adult lymphocytes to secrete the T helper type 2-derived immunosuppressive cytokines IL-4 and IL-10. Taking into account that the feto-maternal environment is rich in cAMP-elevating agents, the reduced risk of graft versus host disease associated with cord blood trasplantation, as compared with the risk with adult bone marrow cell transplants, may be due to the bias of neonatal cells to differentiate towards the T helper type 2 functional cell subset.

Immunology at the maternal-fetal interface: lessons for T cell tolerance and suppression

Mammalian reproduction poses an immunological paradox because fetal alloantigens encoded by genes inherited from the father should provoke responses by maternal T cells leading to fetal loss. Current understanding of T cell immunobiology and the critical role of inflammatory processes during pregnancy is reviewed and discussed. Lessons derived from studies on the regulation of T cell responsiveness during mammalian gestation are considered in the wider context of T cell tolerance toward some microbial infections and tumors, avoidance of autoimmunity, and tissue allograft rejection.

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

Control of antifetal immune responses is thought to be regulated locally by the placenta. Because the physiologic programming of the placenta across gestation is likely to influence the local immunity, we hypothesize that a potent anti-inflammatory cytokine such as IL-10 may be produced in a gestational age-dependent manner. In the present study, we examined the expression of IL-10 and its receptor in placental explants or freshly isolated cytotrophoblasts from different gestational ages and compared it with the expression profiles of other cytokines. First and second trimester placental tissues from normal pregnancies predominantly expressed IL-10, whereas the levels of IL-2, IL-4, and IFN-gamma were mostly below detection throughout pregnancy. The expression of IL-10, but not its receptor, diminished significantly in term placental tissues collected "before" the onset of labor and did not change appreciably "after" labor. On the other hand, TNF-alpha and IL-1beta were significantly up-regulated in response to labor-associated conditions. IL-10 expression was transcriptionally attenuated at term as observed in cytotrophoblasts. In contrast to the placental cytokine milieu, autologous PBMCs, when activated with PHA, secreted significant amounts of IL-2, IL-4, IL-10, and IFN-gamma, albeit with a statistically significantly enhanced IL-10 production in first trimester compared with age-matched nonpregnant women. These data suggest that IL-10 is expressed in the placenta in a gestational age-dependent manner and that its down-regulation at term may be an important mechanism underlying the subtle changes associated with parturition.

gammadelta T cells of human early pregnancy decidua: evidence for cytotoxic potency

The immune compromise in decidua allows a semiallogeneic fetus to survive without impairing the ability of the maternal immune system to fight infections. Cytotoxic mechanisms are likely to be important in this compromise. Using RT-PCR, immunoflow cytometry and immunoelectron microscopy, the cytotoxic potential of isolated human decidual gammadelta T cells was studied. mRNA for perforin (Pf), granzymes A and B, granulysin and Fas ligand (FasL) was simultaneously expressed in decidual gammadelta T cells. Pf and FasL were not expressed on the cell surface. However, the cells constitutively synthesized Pf and stored it in cytolytic granules. Within the granules Pf mainly resided in the granule core formed by Pf-containing microvesicles. Ultrastructurally, three groups of Pf-containing granules were distinguished. They probably represent different stages of granule maturation in a process where Pf-containing microvesicles first attach to the core cortex and then are translocated across the cortex into the core. Presynthesized FasL was also stored in the core and microvesicles of the cytolytic granules. Upon degranulation by ionomycin/Ca(2+) treatment, FasL was rapidly translocated to the cell surface, demonstrating that its surface expression was not controlled by de novo biosynthesis. Thus decidual gammadelta T cells appear to perform Pf- and FasL-mediated cytotoxicity utilizing a common secretory mechanism based on cytolytic granule exocytosis. The first cytochemical visualization of lipids in the cytolytic granules is provided. These intragranular lipids probably wrap up the core and participate in packaging of the cytotoxic proteins as well as in the killing process. An ultrastructural model of a cytolytic granule is presented.

Successful treatment of immunologic abortion with low-dose intravenous immunoglobulin

OBJECTIVE

To evaluate the efficacy of low-dose intravenous immunoglobulin (IVIG) treatment in older women with immunologic abnormalities and recurrent spontaneous abortion (RSA), a condition referred to as immunologic abortion.

DESIGN

Prospective clinical trial.

SETTING

Outpatient referral practice.

PATIENT(S)

Forty-seven women were enrolled in the study. The mean age of the women was 37 years (range, 28-45 years), and the mean number of prior miscarriages was 3.7. Immunologic abnormalities included antiphospholipid antibodies (32%), antithyroid antibodies (53%), antinuclear antibodies (28%), antiovarian antibodies (2%), increased natural killer cells (40%), increased immunoglobulin (Ig)M level (28%), and increased CD4/CD8 T-cell ratio (15%). One patient had IgA deficiency, and three women had endometriosis. Thirty-one of the 47 patients (66%) had more than one immunologic abnormality.

INTERVENTION(S)

Treatment with IVIG at a dose of 0.2 g/kg within 2 weeks of attempted conception. Once conception was achieved, IVIG treatment was continued on a monthly basis at the same dose through 26-30 weeks of gestation.

MAIN OUTCOME MEASURE(S)

Successful pregnancy or recurrent abortion.

RESULT(S)

Of the 47 women, 36 received initial IVIG treatment, and 24 subsequently became pregnant. Of these women, 20 continued IVIG treatment through 26-30 weeks of gestation, and 19 (95%) had a successful term pregnancy. Four women discontinued IVIG therapy after 10-12 weeks of gestation, and 3 (75%) had a successful pregnancy outcome. Of the 11 women who refused IVIG therapy, 7 became pregnant, and all 7 miscarried. The difference in pregnancy success rate between the IVIG-treated and untreated groups was significant (P=.001). Three women had adverse reactions during the low-dose IVIG infusion, and these reactions resolved when the IVIG brand was changed. Fetal abnormalities were not observed.

CONCLUSION(S)

Low-dose IVIG therapy is beneficial for older women with immunologic abortion. The optimum duration of IVIG treatment in these women requires further study.

Human amniotic fluid lacks interleukin-2 and interleukin-15 but can interact with the beta-chain of the interleukin-2 receptor

The present study investigated whether an explanation for the conflicting reports on the interleukin-2 (IL-2) status of amniotic fluid is due to the presence of IL-15 which shares biological activities with IL-2 and utilizes the IL-2 receptor beta-chain. Amniotic fluids from 45 normally progressing pregnancies between 14 and 16 weeks after the last menstrual period were assayed for IL-2 and IL-15 by bioassay and enzyme-linked immunosorbent assay (ELISA). The ability of amniotic fluids to induce cytotoxic T lymphoblastoid line-2 (CTLL-2) cell proliferation was demonstrated to be dependent upon bioassay culture conditions. In serum-free medium each amniotic fluid stimulated CTLL-2 proliferation with a mean level of IL-2-like bioactivity of 14.7 +/- 2.3 ng/ml but amniotic fluids failed to induce CTLL-2 proliferation in serum-supplemented medium. Treatment with neutralizing anti-IL-2 or anti-IL-15 antibodies failed to inhibit amniotic fluid-induced CTLL cell proliferation in serum-free medium, indicating a lack of IL-2 and IL-15 bioactivity. In contrast, treatment with anti-IL-2 receptor beta-chain antibody significantly reduced amniotic fluid-induced proliferation. The lack of IL-2 and IL-15 activity in amniotic fluids was confirmed using ELISA. Although high levels of IL-15 immunoactivity were detected in all samples, specificity controls showed a lack of specific IL-15 immunoactivity in amniotic fluid. Pretreatment of amniotic fluids with 100-500 ng/ml mouse immunoglobulin G abrogated IL-15 immunoactivity, indicating that amniotic fluid contains molecules binding to Fc regions of immunoglobulins and responsible for false ELISA positivity. These studies unequivocally show that amniotic fluid lacks IL-2 and IL-15 but can stimulate CTLL-2 cell proliferation via the IL-2 receptor beta-chain. The absence of IL-2 and IL-15 in normal mid-trimester amniotic fluid suggests that the cytokine profile of human pregnancy appears to be associated with a bias against type 1 cytokines within the feto-placental unit.

IL-12, IL-6 and IFN-gamma production by lymphocytes of pregnant women with rheumatoid arthritis remission during pregnancy

BACKGROUND

Rheumatoid arthritis (RA) is an autoimmune disease with progressive activity. The RA remission was observed in women during pregnancy, but the mechanism responsible for remission is hypothetical only and concerns mechanisms of immune regulation such as lymphocyte subpopulations and interleukin production.

AIMS

The lymphocyte subpopulations and interleukin production in vitro in a group of healthy non-pregnant women, healthy pregnant women and pregnant women suffering from RA may help towards a better understanding of regulation of the immune processes.

METHODS

The investigations were performed in trimester III--2 days after delivery and 6 weeks after delivery. Peripheral blood lymphocytes were isolated on Gradisol gradient and analysed immediately or after having been cultured for 72 hours in RPMI medium supplemented with 10% FCS. The cultures were terminated after 72 h, supernatants stored at -72 degrees C for interleukin evaluation. The concentrations of IFN-gamma, IL-2, IL-6, IL-12, TNF-alpha and its soluble receptors R-I, R-II were estimated in non-stimulated and PHA (Sigma, 5 microg/ml) stimulated culture supernatants using ELISA Endogen kits according to the manufacturer's instructions.

RESULTS

The general pattern of T cell subpopulation distribution was similar in all analysed groups. Decreased IFN-gamma, IL-12 and increased IL-6 production by lymphocytes after PHA stimulation was found in trimester III in pregnant women with RA as compared to healthy pregnant woman.

CONCLUSION

The obtained results suggest that in pregnant women with RA the TH1 cell response predominates, contrary to healthy pregnant women with TH2 type functional response. These phenomena were not observed after delivery.

A Null Mutation in the Inflammation-Associated S100 Protein S100A8 Causes Early Resorption of the Mouse Embryo

S100A8 (also known as CP10 or MRP8) was the first member of the S100 family of calcium-binding proteins shown to be chemotactic for myeloid cells. The gene is expressed together with its dimerization partner S100A9 during myelopoiesis in the fetal liver and in adult bone marrow as well as in mature granulocytes. In this paper we show that S100A8 mRNA is expressed without S100A9 mRNA between 6.5 and 8.5 days postcoitum within fetal cells infiltrating the deciduum in the vicinity of the ectoplacental cone. Targeted disruption of the S100A8 gene caused rapid and synchronous embryo resorption by day 9.5 of development in 100% of homozygous null embryos. Until this point there was no evidence of developmental delay in S100A8−/− embryos and decidualization was normal. The results of PCR genotyping around 7.5–8.5 days postcoitum suggest that the null embryos are infiltrated with maternal cells before overt signs of resorption. This work is the first evidence for nonredundant function of a member of the S100 gene family and implies a role in prevention of maternal rejection of the implanting embryo. The S100A8 null provides a new model for studying fetal-maternal interactions during implantation.