The emerging role of immunoregulation of fibrinogen-related procoagulant Fgl2 in the success or spontaneous abortion of early pregnancy in mice and humans

DIA-based quantitative proteomic analysis of porcine endometrium in the peri-implantation phase

The 12th day of gestation is a critical period for embryo loss and the beginning of imminent implantation in sows. Data independent acquisition (DIA) technology is one of the high-throughput, high-resolution and reproducible proteomics technologies for large-scale digital qualitative and quantitative research. The aim of this study was to identify and characterize the protein abundance landscape of Yorkshire pig endometrium on the 12th day of pregnancy (P12) and estrous cycle (C12) using DIA proteomics. A total of 1251 differentially abundant proteins (DAPs) were identified, of which 882 were up-regulated and 369 were down-regulated at P12. Functional enrichment analysis showed that the identified proteins were related to metabolism, biosynthesis and signaling pathways. Three proteins were selected for Western blot (WB) validation and the results were consistent with the DIA data. Further combined with transcriptome data, fibrinogen like 2 (FGL2) and S100 calcium binding protein A8 (S100A8) were verified to be highly abundant in the P12 endometrial epithelium. In summary, there were significantly different abundance of proteome profiles in C12 and P12 endometrium, suggesting that DAPs are associated with changes in endometrial receptivity, which laid the foundation for further research on related regulatory mechanisms. SIGNIFICANCE: The 12th day of gestation is an important point in the peri-implantation period of pigs, when the endometrium presents a receptive state under the stimulation of estrogen. DIA proteomics technology is an emerging protein identification technology in recent years, which can obtain protein information through comprehensive and unbiased scanning. In this study, DIA technology was used to characterize endometrial proteins in pigs during the peri-implantation period. The results showed that higher protein abundance was detected using the DIA technique, and some of these DAPs may be involved in regulating embryo implantation. This study will help to better reveal the related proteins involved in embryo implantation, and lay a foundation for further research on the mechanism of endometrial regulation of embryo implantation. SIGNIFICANCE OF THE STUDY: The 12th day of gestation is an important point in the peri-implantation period of pigs, when the endometrium presents a receptive state under the stimulation of estrogen. DIA proteomics technology is an emerging protein identification technology in recent years, which can obtain protein information through comprehensive and unbiased scanning. In this study, DIA technology was used to characterize endometrial proteins in pigs during the peri-implantation period. The results showed that higher protein abundance was detected using the DIA technique, and some of these DAPs may be involved in regulating embryo implantation. This study will help to better reveal the related proteins involved in embryo implantation, and lay a foundation for further research on the mechanism of endometrial regulation of embryo implantation.

Inflammatory conditions promote a switch of oligosaccharyltransferase (OST) catalytic subunit isoform expression

Oligosaccharyltransferase (OST) complex catalyzes the N-glycosylation of nascent polypeptides in the endoplasmic reticulum. Glycoproteins are critical for normal cell-cell interactions, especially during an immune response. Abnormal glycosylation is an insignia of several inflammatory diseases. However, the mechanisms that regulate the differential N-glycosylation are not fully understood. The OST complex can be assembled with one out of two catalytic subunits, STT3A or STT3B, which have different enzymatic properties. In this work, we investigated the expression of STT3A and STT3B in several mouse models such as a crossbreeding of normal and abortion-prone mice and an intestinal inflammation model. These animals were either exposed or not to acoustic stress (acute or chronic). The expression of the isoforms was analysed by immunohistochemistry and protein immunoblot. Finally, we investigated the gene regulatory elements employing public databases. Results demonstrated that inflammation alters the balance between the expression of both isoforms in the affected tissues. In homoeostatic conditions, STT3A expression predominates over STT3B, especially in epithelial cells. This relation is reversed as a consequence of inflammation. An increase in STT3B activity was associated to the generation of mannose-rich N-glycans. Accordingly, this type of N-glycans were found to decorate diverse inflamed tissues. The STT3A and STT3B genes are differentially regulated, which could account for the differences in the expression levels observed here. Our results support the idea that these isoforms could play different roles in cellular physiology. This study opens the possibility of studying the STT3A/STT3B expression ratio as a biomarker in acute inflammation or chronic diseases.

Evaluation of T cell cytokines and their role in recurrent miscarriage

Recurrent miscarriage (RM) is defined as two or more consecutive pregnancy losses that affect approximately 5% of conceived women worldwide. RM is a multi-factorial reproductive problem and has been associated with parental chromosomal abnormalities, embryonic chromosomal rearrangements, uterine anomalies, autoimmune disorders, endocrine dysfunction, thrombophilia, life style factors, and maternal infections. However, the exact cause is still undecided in remaining 50% of cases. Immunological rejection of the embryo due to exacerbated maternal immune reaction against paternal embryonic antigens has been set forth as one of the significant reason for RM. The accurate means that shield the embryo during normal pregnancy from the attack of maternal immune network and dismissal are inadequately implicit. However, it is suggested that the genetically irreconcilable embryo escapes maternal immune rejection due to communication among many vital cytokines exuded at maternal-embryonic interface both by maternal and embryonic cells. Previous investigations suggested the Th1/Th2 dominance in altered immunity of RM patients, according to which the allogenic embryo flees maternal T cell reaction by inclining the Th0 differentiation toward Th2 pathway resulting into diminished pro-inflammatory Th1 immunity. However, recently pro-inflammatory Th17 cells and immunoregulatory Treg cells have been discovered as essential immune players in RM besides Th1/Th2 components. Cytokines are believed to develop a complicated regulatory network so as to establish a state of homeostasis between the semi-allogenic embryo and the maternal immune system. However, an adverse imbalance among cytokines at maternal-embryonic interface perhaps due to their gene polymorphisms may render immunoregulatory means not enough to re-establish homeostasis and thus may collapse pregnancy.

mRNA/lncRNA expression patterns and the function of fibrinogen-like protein 2 in Meishan pig endometrium during the preimplantation phases

Embryonic implantation involves a complex and well-coordinated interaction between the developing conceptus and maternal uterus, and the preimplantation period has a major impact on litter size in pigs. The present study aimed to investigate the vital messenger RNAs (mRNAs) and long noncoding RNAs (lncRNAs) that regulate preimplantation in Meishan pigs. The enriched Gene Ontology terms were all related to "binding." Furthermore, "ECM-receptor interaction" was predicted as an important pathway that regulated the success of implantation. We speculated that the differentially expressed mRNAs S100A9, ANXA8, MUC16, and FGL2 and the differentially expressed lncRNAs TCONS_11206566, TCONS_09904861, and TCONS_1252933 may play vital roles in the process of implantation. Furthermore, this study verified that FGL2 was highly expressed on Day 12 of pregnancy, and we also investigated the function of FGL2 during preimplantation in vivo. In conclusion, this study provides useful information for further analyses of the molecular mechanisms of implantation in Chinese domestic pigs.

Effects of low molecular weight heparin on the polarization and cytokine profile of macrophages and T helper cells in vitro

Low molecular weight heparin (LMWH) is widely used in recurrent miscarriage treatment. The anti-coagulant effects are established, while immunological effects are not fully known. Our aim was to assess LMWH effects on activation and polarization of central regulatory immune cells from healthy women, and on placenta tissues from women undergoing elective abortions. Isolated blood monocytes and T helper (Th) cells under different activation and polarizing conditions were cultured with or without LMWH. Flow cytometry showed that LMWH exposure induced increased expression of HLA-DR and CD206 in macrophages. This phenotype was associated with increased secretion of Th17-associated CCL20, and decreased secretion of CCL2 (M2-associated) and CCL22 (Th2), as measured by multiplex bead array. In accordance, LMWH exposure to Th cells reduced the proportion of CD25highFoxp3+ regulatory T-cells, intensified IFN-γ secretion and showed a tendency to increase the lymphoblast proportions. Collectively, a mainly pro-inflammatory effect was noted on two essential tolerance-promoting cells. Although the biological significancies of these in vitro findings are uncertain and need to be confirmed in vivo, they suggest the possibility that immunological effects of LMWH may be beneficial mainly at an earlier gestational age to provide an appropriate implantation process in women with recurrent miscarriage.

OLR1 and Loxin Expression in PBMCs of Women with a History of Unexplained Recurrent Miscarriage: A Pilot Study

AIMS

The aim of this study was to evaluate the expression of OLR1 and its alternative splicing isoform Loxin in unexplained recurrent miscarriage (uRM).

METHODS

Sixty-three women of reproductive age were recruited and were divided into four groups: 18 pregnant and 23 non-pregnant women with uRM, and 12 pregnant and 10 non-pregnant women with physiological pregnancies. Complementary DNA derived from peripheral blood mononuclear cells (PBMCs) was analyzed by quantitative real-time PCR to evaluate the expression of OLR1 and Loxin. Oxidized low-density lipoproteins (ox-LDLs) were assayed from serum by a commercially available kit.

RESULTS

Pregnant uRM women presented with a higher, though not significant, OLR1/Loxin ratio and a higher ox-LDLs serum level (p ≤ 0.05) compared with pregnant control women. OLR1 and Loxin levels were significantly decreased in non-pregnant uRM women compared with the control (OLR1: 0.00018 vs. 0.00043, p ≤ 0.005; Loxin: 0.00018 vs. 0.00060, p ≤ 0.005, respectively). Loxin expression decreased by about two-thirds (p ≤ 0.005) in pregnant women compared with non-pregnant control women. A higher expression of OLR1 in pregnant women compared with non-pregnant women with uRM (p ≤ 0.05) was observed, but no variation in Loxin expression was observed.

CONCLUSIONS

The results of this study show an association of peripheral OLR1 and Loxin expression levels in uRM women, and they suggest the possible existence of an uncontrolled oxidative stress in these women in the first trimester of pregnancy.

The Role of C5a Receptor Signaling in Endotoxin-Induced Miscarriage and Preterm Birth

PROBLEM

Complement factor 5a (C5a), a potent pro-inflammatory mediator of the complement system, has been implicated in fetal rejection throughout gestation, from miscarriage to preterm birth. This study aimed to investigate the role of the principal C5a receptor, C5aR1 (CD88), in both miscarriage and preterm birth, in a bacterial endotoxin (lipopolysaccharide; LPS) murine model.

METHOD OF STUDY

Wild-type and C5ar1 knockout mice were administered LPS at 9.5 or 15.5 days post-conception to induce miscarriage or preterm birth, respectively.

RESULTS

C5ar1 knockout mice were protected against miscarriage in response to administration of LPS in early gestation. However, the absence of C5aR1 had no effect on the rates of preterm birth when LPS was administered in late gestation.

CONCLUSION

There may be a gestational window in which excessive activation of C5a can exert deleterious effects in pregnancy. Future strategies targeting the C5a-C5aR1 signaling axis should be considered to ameliorate miscarriages in patients with recurrent pregnancy loss.

Correlation of fibrinogen-like protein 2 with disease progression in patients with severe acute pancreatitis

It has recently been demonstrated that fibrinogen-like protein 2 (fgl2) is expressed on the surface of macrophages, T cells and endothelial cells and directly cleaves prothrombin to thrombin. The present study was designed to examine fgl2 expression in patients with severe acute pancreatitis (SAP) and its correlation with disease progression. Peripheral blood mononuclear cells (PBMCs) were isolated from 25 patients with SAP, 37 patients with mild acute pancreatitis (MAP) and 20 healthy volunteers as controls. Paraffin sections of pancreas were obtained from 18 postoperative patients with SAP between 2003 and 2012. Human fgl2 (hfgl2) gene expression was determined in the PBMCs by real-time PCR. A monoclonal antibody against hfgl2 was applied to detect hfgl2 protein expression in the pancreatic tissues as well as in the PBMCs by immunohistochemical staining. The levels of hfgl2 expression in the PBMCs from the 25 patients with SAP were markedly upregulated compared with the other groups, whereas no significant difference between the MAP group and healthy controls was observed. hfgl2 expression in the PBMCs and pancreatic tissues was detectable through using immunohistochemistry and was demonstrated to be specifically localized to the endothelium of microvessels and inflammatory infiltrative cells in the areas of acute focal, confluent necrosis. There were positive correlations between hfgl2 expression in the PBMCs and the severity of SAP, as indicated by scores of Ranson and Acute Physiology and Chronic Health Evaluation II. The results suggest that hfgl2 is involved in the pathogenesis of SAP and hfgl2 levels may serve as a biomarker during disease progression.

Stress increases VCAM-1 expression at the fetomaternal interface in an abortion-prone mouse model

Sound stress exposure increases fetal loss via inflammatory pathways. Inflammation is known to up-regulate cell adhesion molecules, such as vascular cell adhesion molecule-1 (VCAM-1), which mediates the adhesion of leukocytes to the vascular endothelium. In this work, we studied the frequency of VCAM-1(+) vessels at the fetomaternal interface in stressed and non-stressed pregnant CBA/J female mice mated with DBA/2J (high fetal loss model) or BALB/c (low fetal loss model) males. The high fetal loss model had fewer large vessels on gestation day 6.5, and stress reduced the frequency of large vessels to a similar number in both high and low fetal loss models. In the high fetal loss model, however, the frequency of VCAM-1+ vessels was dramatically increased. This study shows that VCAM-1 expression is modulated by stress at the fetomaternal interface in abortion-prone cross-breeding.

Expression and significance of fgl2 prothrombinase in cardiac microvascular endothelial cells of rats with type 2 diabetes

Microthrombosis may be involved in the pathogenesis of cardiac microangiopathy due to diabetes. Recent studies have shown that fibrinogen-like protein 2 (fgl2) plays a pivotal role in microthrombosis in viral hepatitis, acute vascular xenograft rejection and cytokine-induced fetal loss syndrome. The current study was designed to examine the expression of fgl2 in microvascular endothelial cells and investigate the effects of microthrombi due to fgl2 on cardiac function and structure in rats with type 2 diabetes. Following induction of type 2 diabetes, 24 rats were observed dynamically. Fgl2 expression and related cardiac microthrombosis were examined. Local or circulating TNF-α was measured. Coronary flow (CF) per min was calculated as an index of cardiac microcirculation. Cardiac function and morphology were evaluated. It was found that Fgl2 was highly expressed in cardiac microvascular endothelial cells of rats with type 2 diabetes, which was promoted by local or circulating TNF-α. The Fgl2 expression was associated with cardiac hyaline microthrombosis. In parallel with the fgl2 expression, CF per min, cardiac diastolic or systolic function and cardiac morphology were aggravated to some extent. It was concluded that in rats with type 2 diabetes, microthrombosis due to fgl2 contributes to the impairment of cardiac diastolic or systolic function and morphological changes.

Use of Heparin in Women With Early and Late Miscarriages With and Without Thrombophilia

Objective: In women with a history of recurrent miscarriage, the risk of miscarriage in a subsequent pregnancy is about 30% to 40%. In patients with thrombophilia, the risk is even higher. Placental thrombosis has been found in women with unexplained recurrent miscarriage independent of thrombophilia. In addition, proinflammatory changes, for example, altered Th1 to Th2 cytokine ratio and complement activation, have been repeatedly demonstrated in these women. Because of the fact that heparin has both anticoagulative and anti-inflammatory effects, the current study evaluated the efficacy of low-molecular-weight heparin (LMWH) in unexplained abortions. Study Design: A total of 164 women with unexplained early and late miscarriages presented in our hemostaseological clinic for thrombophilia screening. For these 164 women, 82 subsequent pregnancies in 79 patients were treated with subcutaneous LMWH independently of thrombophilia. In 54/82 unselected pregnancies, 100 mg aspirin was administered in addition to LMWH. Two patients were excluded due to termination of pregnancy. Results: Overall, 83.8% (67/80) of pregnancies resulted in live births. In 22/79 women (27.8%), thrombophilia markers were positive. Most noteworthy, patients with thrombophilia markers had live births at a similar frequency as patients without those parameters. No severe side effects of LMWH were seen. Conclusions: Our data support the notion that LMWH is efficacious in patients with recurrent abortions and thrombophilia. We demonstrated the same effect of LMWH in women with unexplained abortions without thrombophilia. The potential mechanism of action of LMWH in early and late abortions warrants further study.

Role of TNF-α in human female reproduction

TNF-α is a highly versatile cytokine, playing an important role in both apoptosis and inflammation, which is central to reproduction. It belongs to the Th1 type of cytokines. Thus, TNF-α is a proinflammatory cytokine and is involved during follicle development and ovulation, corpus luteum formation and regression and cyclic endometrium function. It has been postulated to be detrimental to the survival of the conceptus due to apoptosis of human primary villous trophoblast cells, leading to miscarriage. However, TNF-α may have a dual role in early pregnancy. Hormonally regulated uterine TNF-α in the mother is probably essential for trophoblast cell invasion, while increased production of TNF-α by maternal macrophages may facilitate labor. The current knowledge on the role of TNF-α and its receptors in the female reproduction is described in this review.

Toxoplasma gondii-induced foetal resorption in mice involves interferon-gamma-induced apoptosis and spiral artery dilation at the maternofoetal interface

The severity of congenital toxoplasmosis depends on the stage of the pregnancy at which infection takes place. Infection during the first trimester generally leads to miscarriage, through an unknown mechanism. Toxoplasma gondii infection is normally controlled by a strong Th1-type response with IFN-gamma production. To investigate the mechanisms of foetal resorption induced by T. gondii, pregnant Swiss-Webster mice were infected 1 day post coïtum with the avirulent Me49 strain. Mated recipients were examined at mid-gestation. Few parasites and no cytolytic effects were detected 10 days post coïtum in implantation sites undergoing resorption. Resorption was accompanied by haemorrhage, spiral artery dilation, hypocellularity of the decidua basalis, apoptosis of placental cells, a decline in uterine mature natural killer cell numbers, increased indoleamine 2,3-dioxygenase mRNA levels and reduced IL-15 mRNA levels. Given the role of IFN-gammaR(-/-) in non-infectious abortive processes, IFN-gammaR(-/-) mice were used to investigate its local role in T. gondii-induced foetal resorption. IFN-gammaR(-/-) mice showed 50% less foetal resorption than their wild-type counterparts, and spiral artery dilation and placental cell apoptosis were both abolished. These results strongly suggest that, at least in mice, T. gondii-induced abortion in early gestation is not due to a direct action of the parasite at the maternofoetal interface but rather to massive IFN-gamma release.

Pravastatin prevents miscarriages in mice: role of tissue factor in placental and fetal injury

Pregnancy loss and intrauterine growth restriction (IUGR) are serious pregnancy complications, and the triggers and mediators of placental and fetal damage are not completely understood. Using a mouse model of recurrent spontaneous miscarriages (DBA/2-mated CBA/J mice) that shares features with human recurrent miscarriage and fetal growth restriction, we identified tissue factor (TF) as an essential participating factor in placental and fetal injury. We have previously shown that C5a releases antiangiogenic molecule sFlt-1 in monocytes that causes defective placental development and fetal death in DBA/2-mated CBA/J mice. In this study, we found that TF not only activates the coagulation pathway, but it also mediates sFlt-1 release in monocytes causing defective placental development and fetal death. Blockade of TF with a monoclonal antibody inhibited sFlt-1 release, prevented the pathological activation of the coagulation pathway, restored placental blood flow, prevented placental oxidative stress, and rescued pregnancies. We also demonstrated that pravastatin, by down-regulating TF expression on monocytes and trophoblasts, prevented placental damage and protected pregnancies in DBA/2-mated CBA/J mice. These studies indicate that TF is an important mediator in fetal death and growth restriction and that statins may be a good treatment for women with recurrent miscarriages and IUGR.

Recurrent miscarriages: What is the role of cytokines?

Recurrent miscarriage is defined as three or more consecutive miscarriages before 20 weeks of gestation. This condition is a frequent reproductive problem worldwide, affecting up to 1% of couples. Immune effector cell dysfunction has been implicated in the pathogenesis of early pregnancy loss. This dysfunction may involve defects in cytokines, growth factors and immunosuppressive factors at the maternofetal interface. This is a growing research field, especially the role of cytokines in recurrent miscarriage.

LPS-induced murine abortions require C5 but not C3, and are prevented by upregulating expression of the CD200 tolerance signaling molecule

PROBLEM

Lipopolysaccharide (LPS) acts via tlr4 to promote Th1 cytokine secretion and abortions. LPS is an essential co-factor in spontaneous abortion in the CBA x DBA/2 model and in stress-triggered abortions. In the CBA x DBA/2 model, C3a, C5a, and fgl2 prothrombinase participate in triggering inflammation that terminates embryo viability. As fgl2 prothrombinase (via thrombin) can generate C5a, it was predicted that LPS-driven abortions (which require fgl2) would be independent of C3. CD200Fc can prevent abortions in the CBA x DBA/2 model, but an action through Fc could not be excluded.

METHOD OF STUDY

C3(-/-) and C5(-/-) knock-out mice on a B6 background were syngeneically mated and Salmonella enteritidis LPS was administered i.p. on day 6.5 or pregnancy along with 2 mg progesterone in sesame oil s.c. The total number of implants and the number of resorbing embryos were counted on day 13.5 of pregnancy. CD200-rtTA double transgenic homozygous males (B6 background) mated with B6(+/+) females were similarly treated. To up-regulate CD200 expression in embryonic trophoblasts, doxycycline was added to the drinking water from the time of mating.

RESULTS

The LPS boosted the abortion rate from 15.5% (control) to 42.0% in C3(-/-) mice (chi(2) = 9.28, P < 0.005). In C5(-/-) mice, there was no increase in abortion rate with LPS compared to progesterone-treated controls (22.8%versus 26.3%, P = NS). LPS-treated transgenic mice given LPS + progesterone had a 42.5% abortion rate, but when the mice were given doxycycline to induce expression of CD200 by the embryo, the abortion rate was only 8.3% (chi(2) = 14.40, P < 0.005, Fisher's exact test P = 0.00007).

CONCLUSION

C5, but not C3, appears necessary for LPS-driven abortions. Up-regulation of CD200 can prevent LPS-driven abortions, possibly by altering dendritic cells to promote Treg cell development or by a direct suppressive action on macrophages and mast cells that also express CD200 receptors.

Decline in number of elevated blood CD3(+) CD56(+) NKT cells in response to intravenous immunoglobulin treatment correlates with successful pregnancy

PROBLEM

Patients with elevated blood natural killer (NK) cells may be offered intravenous immunoglobulin (IVIG) treatment, but there is controversy about the utility of blood NK cell testing. Human CD56(+) NK cells include several subpopulations that include the putatively cytotoxic CD56(+) CD16(+) subset. In mouse models of pregnant failure, NKT cells appear to be important. However, a mouse model may only be pertinent to a subset of patients, as recurrent pregnancy failure is a heterogenous group.

METHOD OF STUDY

An ethics-approved observational study was done to observe the effect of treatment on total blood lymphoid cells, and subsets of CD56(+) blood lymphocytes including CD56(+) CD3(+) NKT cells determined by flow cytometry, and to correlate with pregnancy outcome. Fifteen fertile women with a history of successful pregnancy and thirty-one women suffering from repeated implantation failure or recurrent spontaneous abortion provided serial blood samples during one menstrual cycle or prior to and during treatment. IVIG was administered to the latter group with or without heparin/aspirin.

RESULTS

Eight of thirty infertile women presented with high numbers of CD56(+) CD3(+) NKT cells, which declined after treatment with IVIG. The elevated NKT cell group with or without concomitant autoimmunity achieved a significantly higher successful pregnancy rate over the course of the study, as compared to women with average numbers of NKT cells and no evidence of autoimmunity (P = 0.018). Elevated NKT levels alone was an independent predictor of success on treatment (P = 0.003).

CONCLUSION

Elevated NKT cells in recurrent pregnancy loss or implantation failure can be ameliorated with IVIG treatment, and result in successful pregnancy. Assay of NKT cell numbers may identify patients who are more likely to benefit from IVIG therapy and merits further examination in randomized phase II studies.

Tolerance signaling molecules and pregnancy: IDO, galectins, and the renaissance of regulatory T cells

PROBLEM

Is the concept of maternal tolerance preventing rejection of the semi-allogeneic 'fetal allograft' still valid?

METHOD OF STUDY

Compilation of expert reviews of literature and recent advances in research on indoleamine-2,3 dioxygenase (IDO), regulatory T cells and galectin-1.

RESULTS AND CONCLUSION

A role for IDO in pregnancy success remains speculative, but solid data exist to support a role for Treg cells, and for galectin-1 in induction and action of Treg cells. Just as several signals may need to be simultaneously present to induce Th1 cytokine-triggered abortions, more than 1 signal may need to be simultaneously present to prevent rejection and ensure success. Both complement and coagulation pathways appear necessary for embryo execution.

Effect of interferon-gamma treatment on the expression of interleukin-1beta at the maternal-fetal interface of pregnant rats

In the present study, the possible mechanisms by which interferon (IFN)-gamma affects pregnancy were investigated using the cytokine network model. The IFN-gamma-induced expression of interleukin (IL)-1beta was examined using western blotting, immunohistochemistry and immunofluorescence. The results showed that IFN-gamma treatment significantly decreased the expression of uterine IL-1beta protein during the preimplantation, post-implantation and mid-gestation periods. The expression of IL-1beta protein was increased after IFN-gamma treatment compared with the control group in late pregnancy. In the placenta, IL-1beta protein levels were significantly increased after IFN-gamma treatment in early and mid-pregnancy. In late pregnancy, IFN-gamma treatment significantly decreased placental IL-1beta protein levels. IL-1beta was mainly expressed in the myometrium, uterine arteries, decidua basalis, trophospongium of the junctional layer and trophoblastic epithelium of the labyrinthine layers. IL-1beta was mainly located in the cytoplasm of in vitro cultured endometrial stromal cells (ESCs). IFN-gamma treatment did not affect the distribution of IL-1beta, only the expression of IL-1beta. The effects of IFN-gamma on the proliferation of ESCs were determined using an MTS (a novel tetrazolium compound) assay. IFN-gamma treatment inhibited the proliferation of ESCs and decreased the weight of the fetus and placenta. These results indicate that exogenous IFN-gamma affects the expression of IL-1beta and inhibits ESC proliferation.

Effects of urinary and recombinant gonadotrophins on gene expression profiles during the murine peri-implantation period

BACKGROUND

Controlled ovarian stimulation (COS) with urinary gonadotrophins but not recombinant gonadotrophins, adversely affect the implantation process. In this study, we investigated the effects of urinary and recombinant gonadotrophins on gene expression profiles at implantation sites during the mouse peri-implantation period and the possible molecular mechanisms involved in the detrimental effects of urinary gonadotrophins using microarray technology.

METHODS

Adult female CD1 mice were treated with (i) urinary human FSH (hFSH) and urinary HCG, (ii) recombinant hFSH and recombinant human LH or (iii) saline. Gene expression profiling with GeneChip mouse genome 430 2.0 arrays, containing 45 101 probe sets, was performed using implantation sites on embryonic day 5. Data were statistically analysed using Significance Analysis of Microarrays. Ten genes from the microarray analysis were selected for validation using quantitative RT-PCR (qRT-PCR). A parallel group of pregnant mice was allowed to give birth to study the effect of gonadotrophins on resorption.

RESULTS

Urinary gonadotrophins differentially up-regulated the expression of 30 genes, increased resorption and reduced litter size, whereas recombinant gonadotrophins did not. Nine of the 10 genes were confirmed by qRT-PCR.

CONCLUSIONS

Urinary gonadotrophins, but not recombinant gonadotrophins, exerted differential effects on gene expression during the murine peri-implantation period. These findings might contribute to improve protocols for COS, leading to higher successful pregnancy rates.

Immunological analogy between allograft rejection, recurrent abortion and pre-eclampsia - the same basic mechanism?

There are still controversies concerning the role of immunological mechanisms engaged both in recurrent abortions (RA) and pre-eclampsia (PE). According to some opinions, recurrent miscarriage is comparable to organ-specific autoimmune disease. Analysis of immune reactions shows that graft rejection shares many similar mechanisms with RA and PE. This fact allows us to conclude that rejection of transplanted alloantigenic organs and pregnancy loss have probably the same evolutionary origin. Subsets and functions of immunocompetent cells (T CD4, suppressor gammadeltaT, cytotoxic T CD8, Treg, Tr1, uterine NK cells), over-activation of innate immunity (activation of NK cytotoxic cells, macrophages, neutrophils and complement), changes of Th1/Th2 cytokine balance (IL-2, IL-12, IL-15, IL-18, IFNgamma, TNFalpha vs. IL-4, IL-10, TGFbeta), importance of HLA-G molecule, CD200/CD200R interaction, over-expression of adhesion molecules, fgl2 prothrombinase activation and stimulation of IDO and HO expression, all suggest that RA and PE are syndromes of fetal allograft rejection, and not organ-specific autoimmune diseases. According to that supposition, an analogy might exist between acute graft rejection and recurrent abortion, and between chronic graft rejection and pre-eclampsia.

Stress and substance P but not the substance P-metabolite SP5-11 trigger murine abortion by augmenting TNF-alpha levels at the feto-maternal interface

In a well-established murine abortion model, stress is thought to trigger fetal rejection by inducing a proinflammatory immune response via substance P (SP), being tumour necrosis factor (TNF)-alpha-producing CD8+ T cells involved. Interestingly, the SP metabolite SP5-11 also binds to SP receptors and mediates SP-like effects on immune cells at sites of inflammation. No data were available regarding the effects of SP5-11 on pregnancy outcome in the CBA/J x DBA/2J abortion-prone combination. We investigated the influence of SP5-11 in contrast to stress or SP on the abortion rate and the cytokine production by lymphocytes as well as on the levels of CD8+ T cells. Stress and SP boosted the abortion rate and increased the percentage of type 1 [TNF-alpha, interferon-gamma, interleukin (IL)-12] and type 2 (IL-4 and IL-10) cytokine-producing lymphocytes in blood and decidua, predominantly CD8+ T cells. Interestingly, SP5-11 did not significantly affect the abortion rate or cytokine production in the decidua, while increasing the Th1 and Th2 cytokine production systemically. Our data suggest that stress and SP induce abortion by augmenting the local levels of TNF-alpha, which seems therefore to be a potent trigger of miscarriage. On the contrary, the SP metabolite SP5-11 only affects the systemic cytokine production without boosting the abortion rate in this experimental model.

The role of dydrogesterone in recurrent (habitual) abortion

The published evidence regarding the administration of dydrogesterone in the treatment of habitual abortion is summarised in this review. Habitual abortion is defined as the loss of three or more consecutive pregnancies without known maternal or foetal pathology. The immunology of early pregnancy seems to determine the rejection or non-rejection of the allogenic embryo. When peripheral mononuclear cells from recurrent aborters are incubated with progesterone or dydrogesterone in vitro, T-helper (Th)2 cytokines such as interleukin (IL)-4 and IL-6 markedly increase whereas the Th1 cytokine interferon-gamma decreases. Additionally, both progesterone and dydrogesterone are thought to inhibit the activity of natural killer cells at the foeto-maternal interface in humans. Progesterone-induced blocking factor (PIBF) mediates the immunological effects of progesterone and dydrogesterone in pregnancy. It affects various phases of the maternal immune response involving both the cellular and humoral immune system, exerts anti-abortive effects and inhibits the release of arachidonic acid. It also favours the production of so-called asymmetric, pregnancy-protecting antibodies. In rodents, blockade of this factor results in the termination of pregnancy and in women considerably lower levels are found in those with threatened abortion or pre-term labour. In order to draw final conclusions as to the usefulness of dydrogesterone in women with a history of recurrent miscarriage, further controlled, blinded, randomised clinical trials are needed.

Ecology of Danger-dependent Cytokine-boosted Spontaneous Abortion in the CBA × DBA/2 Mouse Model. I. Synergistic Effect of LPS and (TNF-α + IFN-γ) on Pregnancy Loss

PROBLEM

Previous data have shown "danger" signals, such as bacterial lipopolysaccharide (LPS) acting via toll-like (tlr) receptors are required for early pregnancy failure in several murine abortion models. Indeed, the abortion rate increased in the CBA x DBA/2 model after a gestation day (gd) 7.5 injection of tumour necrosis factor (TNF)-alpha + interferon (IFN)-gamma only if the LPS-tlr signalling pathway was intact. High rates of cytokine-boosted abortion >80% loss can be achieved in certain animal colonies, that have a high endogenous (spontaneous) rate of resorption (30-50%). A specific role for LPS has been postulated to determine both the endogenous and cytokine-boosted losses.

METHODS

To test the role of LPS in spontaneous and cytokine-boosted abortions, recombinant TNF-alpha + IFN-gamma, and LPS were injected in different doses and sequences intraperitoneally (i.p.) into CBA x DBA/2 mated mice in the Toronto General Research Institute animal facility where the endogenous abortion rate is <30%. The effects of poly IC, a tlr3 agonist that induces IFN-gamma that can reverse LPS-induced tolerance, and effects of anti-MD-1 on TNF-alpha induction by LPS, poly IC, CPG, or HSP in vitro were also examined.

RESULTS

A high endogenous rate of loss similar to that seen in Clamart could be achieved by increasing exposure to LPS on the morning after mating (gd 0.5). The magnitude by which the abortion rate could be increased by an i.p. injection of 2000 u TNF-alpha + 1000 u IFN-gamma on gd 7.5 was independent of the endogenous rate of loss, and could not be increased by doubling the dose. One microgram of LPS given on day 7.5 achieved a similar rate of loss, and if given with the cytokines, synergistically boosted the rate of loss to near Clamart rates. LPS given 1 day prior to the cytokines abrogated the cytokine effect, whereas LPS given day 0.5 had no significant effect on the response to day 7.5 cytokine injection. Blocking MD-1 inhibited TNF-alpha stimulation by poly IC, LPS, CPG, or HSP in vitro, and reduced abortion rates. Poly IC did not avert LPS-type tolerance effects in vivo.

CONCLUSIONS

High endogenous rates of abortion in the CBA x DBA/2 model may be explained by exposure to LPS at the time of mating. Increased rates of loss triggered by cytokines later in pregnancy may depend on increased absorption of LPS from intestinal flora.

Region-specific expression and secretion of the fibrinogen-related protein, fgl2, by epithelial cells of the hamster epididymis and its role in disposal of defective spermatozoa

The cauda epididymidis functions in the storage and protection of mature, fertile spermatozoa. We previously identified a region-specific secretory glycoprotein (termed HEP64) of the hamster proximal cauda epididymidis that specifically bound and coated the nonviable, but not the viable, spermatozoa within the epididymal lumen. In this study we employed expression screening of a hamster epididymal cDNA library to obtain the full-length sequence of HEP64 and to identify it as the fibrinogen-like protein fgl2. Northern blot analysis demonstrated that fgl2 mRNA is highly expressed by the proximal cauda epididymidis in comparison to other hamster tissues examined, and, in situ hybridization analysis of the epididymis revealed that fgl2 mRNA exhibited a region- and principal cell-specific expression pattern. Immunohistochemistry confirmed the association of fgl2 with abnormal spermatozoa in the cauda epididymidis and revealed smaller fgl2-containing particles. Immunoelectron microscopy revealed that fgl2 was distributed throughout an amorphous, "death cocoon," complex assembled onto abnormal spermatozoa and that the smaller fgl2 aggregates consisted of the amorphous material with embedded sperm fragments, organelles, and membrane vesicles. A protocol was developed to isolate an enriched death cocoon fraction. SDS-PAGE and microsequence analyses revealed that the Mr 64,000 fgl2 monomer was assembled into two disulfide-linked oligomers of Mr 260,000 and 280,000. These data demonstrate that the epididymis possesses a specific mechanism to identify and envelop defective spermatozoa with a protein complex containing the fibrinogen-like protein fgl2. We propose that this represents an important protective mechanism not only to shield the viable sperm population from potentially deleterious enzymes released by dying spermatozoa but also to prevent the release of sperm proteins that could initiate an immune response if they escaped the epididymal environment.

Systemic and placental productions of tumor necrosis factor contribute to induce fetal mortality in mice acutely infected with Trypanosoma cruzi

Blood levels and placental productions of IFN-gamma and TNF, known to be harmful for pregnancy, were determined in pregnant mice acutely infected with Trypanosoma cruzi and suffering massive fetal losses without congenital infection. INF-gamma was detected mainly at day 9 and TNF at days 17 and 19 of pregnancy in plasma of infected mice. TNF levels were significantly correlated to the percentages of dead fetuses. Placental cells produced TNF but not IFN-gamma, and addition of T. cruzi lysate to such cells strongly stimulated TNF production. Treatment of infected mice with pentoxifylline, known to decrease IFN-gamma production and to inhibit the TNF-alpha gene transcription, reduced the placental production of TNF, and the fetal mortality in comparison to control animals. Altogether these result suggest that TNF produced at systemic and placental levels plays a role in the fetal mortality induced in mice acutely infected with T. cruzi.

Cytokines, implantation and early abortion: re-examining the Th1/Th2 paradigm leads to question the single pathway, single therapy concept

PROBLEM

Human in vitro fertilization (IVF) embryo transfer is accompanied by a low implantation rate even after a very successful IVF, and there are a certain number of 'idiopathic sterilities' which are due to repeated implantation failures. In the very same vein, the question of improving implantation rates is of prime importance in agricultural research to improve the management of livestock. Preimplantation prenatal diagnosis cannot be accomplished in individuals who have a high rate of implantation failure, whether women undergoing IVF, or animals, during genetic cloning. Implantation cytokine networks need to be known in such a perspective.

METHODS

We review the evolution and theories in reproductive immunology, briefly deal with the complexity of implantation as a step by step developmental event, and then present some of our recent data in mice and human.

CONCLUSIONS

We conclude that the T helper cell type 1/2 (Th1/ Th2) paradigm, as useful as it has been to explain pregnancy, is no longer sufficient in view of the emerging complexity of the cytokine network at the materno-fetal interface. This is peculiarly true for implantation, which, as a step by step developmentally regulated process, involving inflammatory molecules, cannot fit into such a scheme.

Determinants of Placental Vascularity

PROBLEM

Vascular growth during implantation and placentation is critical for successful gestation and it is thought that vascular insufficiencies during placentation contribute to a number of obstetrical complications. However, relatively little is known regarding the regulation of angiogenesis in the placenta.

METHOD OF STUDY

We review literature concerning the potential significance of inadequate placental vascularity as a contributor to the obstetrical complications of spontaneous abortion, fetal growth restriction and preeclampsia. Gene expression assays were used to compare fluctuations of placenta growth factor (PlGF) and PlGF receptor expression in normal and preeclamptic trophoblast in vitro.

RESULTS

Studies have shown that common obstetrical complications manifest altered placental vascularity. Both intrinsic defects (gene knockouts) and extrinsic factors (O(2) tension, cytokines, etc) may be responsible for the defects. Some of these factors have been shown to influence trophoblast vascular endothelial growth factor (VEGF)/PlGF expression suggesting this particular family of angiogenic proteins play an important role in placental angiogenesis.

CONCLUSION

Placental vascularization reflects a complex interaction of regulatory factors. Understanding the regulation of vascular growth in the placenta will provide much needed insight into placenta-related vascular insufficiencies.

Regulation of Interleukin-6 Fetoplacental Levels could be Involved in the Protective Effect of Low-molecular Weight Heparin Treatment on Murine Spontaneous Abortion

PROBLEM

CBA/J x DBA/2 abortion rate could be the consequence of a deficient local production of T helper (Th2) cytokines, which cause fetal wastage via fgl2 prothrombinase. Heparin reduces significantly the abortion rate in mice and recurrent spontaneous abortion (RSA) patients. We proposed to determine the effect of enoxaparin on the levels of local interleukin (IL)-6 during murine pregnancy.

METHOD OF STUDY

Recombinant human IL-6 (rhIL-6) or enoxaparin were inoculated in CBA/J x DBA/2 pregnant mice on days 6.5-12.5. IL-6 levels in sera as well as in culture supernatants of day 9.5 fetoplacental units of CBA/J x BALB/c control mice or CBA/J x DBA/2 abortion combination were determined by enzyme-linked immunosorbent assay (ELISA) test.

RESULTS

CBA/J x DBA/2 fetoplacental units secreted significantly lower levels of IL-6 with regard to CBA/J x BALB/c normal units. rhIL-6h and enoxaparin treatments decreased the resorption rate and regulated IL-6 fetoplacental levels.

CONCLUSION

This study suggests that regulation of IL-6 fetoplacental levels could be involved in heparin-mediated anticoagulation protection against abortion.

Placental Trophoblast from Successful Human Pregnancies Expresses the Tolerance Signaling Molecule, CD200 (OX-2)*

PROBLEM

Th1 cytokine-dependent abortions in the CBA x DBA/2 mouse model have been linked to down-regulation of expression of the CD200 (OX-2) 'tolerance' signal on trophoblast and in decidua prior to onset of the abortion process. Abortions could be prevented by administration of a soluble CD200. Is CD200 expressed on trophoblast in successful human pregnancy?

METHOD OF STUDY

As one cannot easily obtain trophoblasts in large quantities from successful human pregnancies in the first trimester prior to the onset of the abortion process at 6 weeks gestation, we examined as a first step, trophoblast isolated from term placentae (i.e. successful pregnancies). CD9- trophoblasts were isolated by affinity column and stained for intracellular cytokeratin, and surface CD200 using PE-anti-human CD200 monoclonal antibody. mRNA was extracted from CD9+ and CD9- cells and tested by reverse transcription-polymerase chain reaction for CD200 mRNA. CD9- placental cells were separated by velocity sedimentation and test for CD200-dependent suppression of an allogeneic human mixed lymphocyte culture where cytotoxic T cell (CTL) generation, and Thl --> Th2 cytokine production shift were measured.

RESULTS

CD9- but not CD9+ placental cell populations contained cells with mRNA for CD200, both a normal length transcript and a truncated transcript. Flow cytometry showed a CD200+ cytokeratin+ moderate-to-large-sized cell population compatible with trophoblasts and a smaller subset of cytokeratin- cells that expressed CD200 at normal and at high levels. The moderate-sized population proved most potent at inhibiting CTL generation and caused a Th1 --> Th2 cytokine shift. These effects were blocked by monoclonal anti-CD200.

CONCLUSIONS

A subpopulation of cytokeratin+ placental trophoblasts express bioactive CD200 able to alter maternal immune responses in a favorable (Th2 > Th1) direction. Two populations of CD200+ small- and medium-small-sized cytokeratin- placental cells remain to be identified. Studies of karyotyped first trimester elective termination and spontaneous miscarriage tissues are needed.

Gene transcription of fgl2 in endothelial cells is controlled by Ets-1 and Oct-1 and requires the presence of both Sp1 and Sp3

The immune coagulant fgl2/fibroleukin has been previously shown to play a pivotal role in the pathogenesis of murine and human fulminant hepatitis and fetal loss syndrome. Constitutive expression of fgl2 transcripts at low levels are seen in cytotoxic T cells, endothelial, intestinal and trophoblast cells, while specific factors (such as virus and cytokines) are required to induce high levels of fgl2 expression in other cell types including monocytes/macrophages. To address the transcriptional mechanisms that regulate constitutive expression of fgl2, murine genomic clones were characterized and the transcription start site was defined by 5'-RACE and primer extension. A comprehensive assessment of basal fgl2 promoter activity in murine vascular endothelial cells defined a minimal 119 bp region responsible for constitutive fgl2 transcription. A complex positive regulatory domain (PRD) spanning a 39-bp sequence from -87 to -49 (relative to the transcription start site) was identified. Electrophoretic mobility shift assay studies in vascular endothelial cells revealed that the nucleoprotein complexes that form on this positive regulatory domain (PRD) contain Sp1/Sp3 family members, Oct-1, and Ets-1. Heterologous expression studies in Drosophila Schneider cells confirmed that the constitutive expression of this gene is controlled by Ets-1 and requires the presence both of the Sp1 and Sp3 transcription factors. The presence of this complex multicomponent PRD in the fgl2 proximal promoter is consistent with the observation that, in vivo, fgl2 expression is tightly regulated. Moreover, viral induced fgl2 expression also requires the presence of this PRD. These results clearly demonstrate that multiple cis DNA elements in a clustered region work cooperatively to regulate constitutive fgl2 expression and interact with inducible elements to regulate viral-induced fgl2 expression in endothelial cells.

Th1 cytokines and the prothrombinase fgl2 in stress-triggered and inflammatory abortion

PROBLEM

The immune system contributes to the outcome of pregnancy by complex immunological interactions. Cytokines especially influence the immune milieu pro or contra pregnancy. T helper 1 (Th1) cytokines [tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma)] cause inflammation and together are thought to threaten the maintenance of pregnancy. It has been proposed that increased levels of these Th1 cytokines activate coagulation via up-regulating the novel prothrombinase, fgl2. This study further investigates the Th1 cytokine up-regulation of fgl2 expression in a pathophysiological, stress induced abortion model, and an inflammatory, interleukin-12 (IL-12) triggered abortion model.

METHOD

The DBA/2J-mated CBA/J female mice were exposed to sonic sound stress or were injected with IL-12 during early gestation. On day 13.5 of pregnancy the uteri were removed and the resorption rate was calculated. We evaluated TNF-alpha, IFN-gamma, fgl2 as well as IL-12 messenger RNA (mRNA) expression in decidual samples of all mice by quantitative, real-time polymerase chain reaction (PCR).

RESULTS

A similar resorption rate of 24% was detected in stressed mice, as well as in IL-12 injected mice compared with approximately 11% in non-stressed, non-injected control mice. In stressed mice compared with controls, we observed on day 13.5 up-regulated TNF-alpha, unchanged IFN-gamma down-regulated fgl2, and a slightly increased levels of IL-12. In the IL-12 triggered abortion model, we observed up-regulated levels of TNF-alpha, IFN-gamma and fgl2.

CONCLUSION

These novel data suggest two distinct cytokine patterns leading to similar abortion rates. A physiological cascade associated with up-regulation of TNF-alpha, and an IL-12-triggered cascade characterized by persistent up-regulation of TNF-alpha and IFN-gamma as well as a persistent increase in fgl2.

FGL2 prothrombinase messenger RNA expression in gravid and nongravid human myometrium

OBJECTIVE

Thrombin is a potent uterotonic agent that may play an important role in human parturition. FGL2 is a prothrombinase that cleaves prothrombin to thrombin. The purpose of this study was to determine FGL2 messenger RNA expression in human myometrium and to assess its relationship to the expression of EP3-6 prostaglandin receptor and inducible nitric oxide synthase.

STUDY DESIGN

Myometrium was obtained from gravid women who underwent cesarean delivery (n = 19), from premenopausal (n = 10) and menopausal (n = 10) women who underwent hysterectomy, and from nonpregnant women who received 200 mg of misoprostol vaginally 12 hours before hysterectomy (n = 8). FGL2 messenger RNA expression was determined with the use of semiquantitative polymerase chain reaction and was compared with previously determined messenger RNA expression levels for EP3-6 and inducible nitric oxide synthase for the same samples. Statistical analysis was performed with the use of independent t test, Fisher exact test, analysis of variance, and linear regression, where appropriate.

RESULTS

All samples that were analyzed contained demonstrable quantities of FGL2 messenger RNA. The highest FGL2 expression was found in gravid women, followed by women who were treated with misoprostol, by premenopausal nonpregnant women, and by menopausal women (P <.0001, analysis of variance). Significantly higher levels of FGL2 expression were found in the gravid women compared with the women who were treated with misoprostol (P <.001), the premenopausal nonpregnant women (P <.001), and the menopausal women (P <.0001). FGL2 messenger RNA expression correlated with EP3-6 and inducible nitric oxide synthase expression in all samples combined (r = 0.55, P <.0001; and r = 0.67, P <.001, respectively).

CONCLUSION

The expression of FGL2 messenger RNA is increased in gravid myometrium compared with nonpregnant samples. Its expression significantly correlates to EP3-6 and inducible nitric oxide synthase expression. FGL2 prothrombinase expression may mediate the role of thrombin in human parturition.

Successful pregnancy with low molecular weight heparin in two women with recurrent miscarriage of unknown etiology

We report here two cases of recurrent miscarriages that were successfully treated with continuous intravenous administration of low molecular weight heparin (LMWH). One patient experienced 11 spontaneous abortions, and the other eight abortions. Previous treatments including prednisone, aspirin and mononuclear-cell immunization were all unsuccessful. They were negative for anticardiolipin antibodies and lupus anticoagulant, and had no inherited thrombophilic disorder. Intravenous administration of LMWH, 4800 units of dalteparin, was started as soon as the conception was confirmed, and was continued until 34 weeks of gestation. They were delivered of live born infants.

Acute Trypanosoma cruzi infection in mouse induces infertility or placental parasite invasion and ischemic necrosis associated with massive fetal loss

Pathogens may impair reproduction in association or not with congenital infections. We have investigated the effect of acute infection with Trypanosoma cruzi, the protozoan agent of Chagas' disease in Latin America, on reproduction of mice. Although mating of infected mice occurred at a normal rate, 80% of them did not become gravid. In the few gravid infected mice, implantation numbers were as in uninfected control mice, but 28% of fetuses resorbed. Such infertility and early fetal losses were significantly associated with high maternal parasitemia. The remaining fetuses presented with reduced weights and all died later in gestation or within 48 hours after birth. Several organs of these fetuses were infiltrated by polynuclear cells and presented ischemic necrosis but did not harbor T. cruzi parasites, discarding congenital infection as the cause of mortality. However, surprisingly, the deciduas were massively invaded by T. cruzi parasites, harboring 125-fold more amastigotes than the maternal heart or other placental tissues. Parasites were significantly more numerous in the placentas of dead fetuses. In addition, placentas contained inflammatory infiltrates and displayed ischemic necrosis, fibrin deposits, and vascular thromboses. These results show that acute T. cruzi infection totally impairs reproduction in mice through inducing infertility or fetal-neonatal losses in association with placental parasite invasion and ischemic necrosis.

The same immunoregulatory molecules contribute to successful pregnancy and transplantation

PROBLEM

At least two dendritic cell-associated molecules have been shown to contribute to the successful outcome of organ and tissue allografts in mice, namely CD200 and MD-1. CD200 is up-regulated in rodent transplantation models where successful inhibition of rejection is accomplished, and is believed to signal immunosuppression following engagement of a receptor, CD200R, on macrophages and/or gammadelta T-cell receptor (gammadelta TCR+ cells MD-1 is implicated in controlling expression of costimulatory molecules including CD80/CD86 which induce an immunorejection response, and thus inhibition of MD-1 expression also facilitates increased graft survival MD-1 also stabilizes expression of CD14, part of the receptor complex for LPS. As well as the inhibition of rejection which follows blockade of MD-1 expression and/or augmentation of CD200 expression, an altered polarization in cytokine production is seen, with increased expression of interleukin-4 (IL-4), IL-10 and transforming growth factor-beta (TGF-beta), and decreased IL-2, interferon-gamma (IFN-gamma) and tumor nerosis factor-alpha (TNF-alpha). Successful pregnancy in allopregnant mice also depends upon control of graft rejection mechanisms. Proinflammatory T-helper 1 (Th1) cytokines (TNF-alpha + IFN-gamma + IL-1) have been shown to cause spontaneous abortion in mice by activating a novel prothrombinase, fibrinogen-like peptide (fibroleukin) fgl2, which may promote fibrin deposition in the graft rejection process; expression of IL-10, TGF-beta, and progesterone-induced blocking factor (PIBF) in contrast leads to lowering of abortion rates. Interestingly, the spontaneous abortion rates in abortion-prone CBA x DBA/2 matings and in the low abortion rate CBA x BALB/c matings were lower than the frequency of implantation sites showing fibrin(hi) + fgl2 (mRNA)hi, implying regulation of the pro-abortion consequences of fgl2 expression.

METHODS

We have investigated, by in situ hybridization, CD200, MD-1 and fgl2 expression in implantation sites in different strains of mice, and studied the effects of anti-MD-1, anti-CD200 and CD200Fc immunoadhesin on fetal and allograft survival. The role of indoleamine dioxygenase (IDO) was evaluated.

RESULTS

CD200 mRNA expression occurred in the same sites as fgl2 mRNA. Anti-CD200 antibody raised the abortion rate to predicted levels, and infusion of a CD200 immunoadhesin reduced the abortion rate, as did an anti-MD-1 antibody. The latter also improved organ and tissue graft survival. Suppression by antigen-presenting macrophages triggered by CD200 is dependent upon intact IDO activity.

CONCLUSION

Regulation of CD200 and MD-1 expression may control both pregnancy and allograft survival.

Brucella abortus siderophore 2,3-dihydroxybenzoic acid (DHBA) facilitates intracellular survival of the bacteria

Siderophores are low molecular weight molecules that allow bacteria to acquire iron from host cell proteins. 2,3-dihydroxybenzoic acid (DHBA) is the only known siderophore produced by the intracellular pathogen Brucella abortus. Here its role in virulence was assessed by evaluating the ability of a mutant with a disruption of the entC gene to survive and replicate in vitro in murine and bovine cells and in vivo in resistant and susceptible murine hosts. It was hypothesized that DHBA is vital for bacterial virulence by its ability to chelate intracellular iron thereby preventing generation of anti-bacterial hydroxyl radicals via the Haber-Weiss reaction, to scavenge reactive oxygen intermediates and for acquisition of iron needed for nutritional purposes. The data showed DHBA played a significant role for bacterial survival in host cells after infection including in murine macrophages cultured in the presence and absence of exogenous interferon-gamma (IFN-gamma) and in bovine trophoblasts supplemented with erythritol. In severely iron-depleted conditions, DHBA was also found to be essential for growth in murine macrophages. Despite these deficiencies, the absence of DHBA had no long-term significant effect on the number of CFU recovered in vivo from either the Brucella-resistant C57BL/6 mice or Brucella-susceptible IFN-gamma knock-out C57BL/6 mice.

Upregulation of decidual P-selectin expression is associated with an increased number of Th1 cell populations in patients suffering from spontaneous abortions

A multicascade of leukocyte-endothelial cell interactions is involved in the trafficking of inflammatory lymphocytes into tissue. The primary contact between leukocytes and endothelium is mediated by selectins. Ligands for P-Selectin are preferentially expressed on Th1 cells and thereby allow migration of these inflammatory cells through the vessel wall. Since a peripheral and local Th1-type cytokine profile is present in spontaneous human abortion (SA), opposed by a Th2 dominant situation in normal pregnancies (NP), we investigated (1) the phenotype of peripheral Th1 cells by flow cytometry, as well as the Th1-type cytokine levels by ELISA, (2) the decidual expression of P- and E-Selectin by immunohistochemistry (IHC), and (3) the phenotype of decidual immunocompetent cells by IHC in patients with NP or SA. We observed enhanced production of IFN-gamma and TNF-alpha in CD8(+), CD3(+), and CD56(+) blood cells, as well as an increase in the number of CCR5(+) cells in patients suffering from SA compared to those with NP. No difference was detectable with respect to the serum levels of the two cytokines. Using IHC methods, we observed increased staining intensity of P-Selectin(+) vessels in samples of SA patients. E-Selectin was only weakly expressed in decidual endothelial cells, with no difference between NP and SA. In SA samples, E-Selectin(+) stromal cells were exclusively present. We further detected increased numbers of decidual CD8(+), CD3(+), CCR5(+), and CD56(+) cells in SA patients. We propose that Th1 lymphocyte migration into decidua is enhanced in SA due to upregulated P-Selectin expression in decidual vessels. This increase of Th1-producing lymphocytes might be involved in the rejection of trophoblasts.