TRAIL (Apo-2L) and TRAIL receptors in human placentas: implications for immune privilege.
(17/1909)
Mechanisms accounting for protection of the fetal semiallograft from maternal immune cells remain incompletely understood. In other contexts, interactions between TRAIL (TNF-related apoptosis-inducing ligand/Apo-2L) and its receptors kill activated lymphocytes. The purpose of this study was therefore to investigate the potential of the TRAIL/TRAIL-R system to protect the placenta against immune cell attack. Analysis by Northern blotting demonstrated mRNAs encoding TRAIL as well as the four TRAIL receptors (DR4, DR5, DcR1/TRID, DcR2/TRUNDD) in human placentas. Immunohistochemical experiments demonstrated that TRAIL protein is prominent in syncytiotrophoblast, an uninterrupted placental cell layer that is continuously exposed to maternal blood, as well as in macrophage-like placental mesenchymal cells (Hofbauer cells). Studies on cell lines representing trophoblasts (Jar, JEG-3 cells) and macrophages (U937, THP-1 cells) showed that both lineages contained TRAIL mRNA and that steady state levels of transcripts were increased 2- to 11-fold by IFN-gamma. By contrast, cell lineage-specific differences were observed in expression of the TRAIL-R genes. Although all four lines contained mRNA encoding the apoptosis-inducing DR5 receptor, only trophoblast cells contained mRNA encoding the DcR1 decoy receptor and only macrophages contained DcR2 decoy receptor transcripts. DR4 mRNA was present only in THP-1 cells and was the only TRAIL-R transcript increased by IFN-gamma. Cytotoxicity assays revealed that the two trophoblast cell lines were resistant, whereas the two macrophage lines were partially susceptible to killing by rTRAIL. Collectively, the results are consistent with a role for the TRAIL/TRAIL-R system in the establishment of placental immune privilege. (+info)
IgM heavy chain complementarity-determining region 3 diversity is constrained by genetic and somatic mechanisms until two months after birth.
(18/1909)
Due to the greater range of lengths available to the third complementarity determining region of the heavy chain (HCDR3), the Ab repertoire of normal adults includes larger Ag binding site structures than those seen in first and second trimester fetal tissues. Transition to a steady state range of HCDR3 lengths is not complete until the infant reaches 2 mo of age. Fetal constraints on length begin with a genetic predilection for use of short DH (D7-27 or DQ52) gene segments and against use of long DH (e.g., D3 or DXP) and JH (JH6) gene segments in both fetal liver and fetal bone marrow. Further control of length is achieved through DH-specific limitations in N addition, with D7-27 DJ joins including extensive N addition and D3-containing DJ joins showing a paucity of N addition. DH-specific constraints on N addition are no longer apparent in adult bone marrow. Superimposed upon these genetic mechanisms to control length is a process of somatic selection that appears to ensure expression of a restricted range of HCDR3 lengths in both fetus and adult. B cells that express Abs of an "inappropriate" length appear to be eliminated when they first display IgM on their cell surface. Control of N addition appears aberrant in X-linked agammaglobulinemia, which may exacerbate the block in B cell development seen in this disease. Restriction of the fetal repertoire appears to be an active process, forcing limits on the diversity, and hence range of Ab specificities, available to the young. (+info)
Secretion of matrix metalloproteinase-2, matrix metalloproteinase-9 and tissue inhibitor of metalloproteinases into the intrauterine compartments during early pregnancy.
(19/1909)
Matrix metalloproteinases (MMPs) are important enzymes in tissue remodelling, a key event for the development of the fetal membranes and placenta and establishing the feto-maternal interface during early pregnancy. This study has examined the secretion of the gelatinases, MMP-2 (72 kDa) and MMP-9 (92 kDa), and the endogenous tissue inhibitors of metalloproteinases (TIMPs) into extra-embryonic coelomic and amniotic fluids, the two principal intra-uterine compartments of the first trimester, and compared them to amniotic fluid collected later in gestation. In extra-embryonic coelomic fluid, gelatin zymography demonstrated that MMP-2 (72 kDa) was the predominant gelatinase, with some MMP-9 present. A broad range of TIMPs corresponding to TIMP-1 and TIMP-2, glycosylated and unglycosylated TIMP-3 and TIMP-4 was detected in this compartment by reverse zymography and immunoblot analyses. There was little gelatinase or TIMP activity in amniotic fluid in the first trimester. In amniotic fluid from the second trimester after fusion of the membranes obliterating the extra-embryonic coelom, and at term elective caesarean section, MMP-2 is the predominant gelatinase present, with a broad spectrum of TIMPs. These findings demonstrate that predominantly MMP-2 and also MMP-9, regulated by a range of TIMPs, are involved in intra-uterine tissue remodelling during the establishment of pregnancy. (+info)
Elevated expression of activation molecules by decidual lymphocytes in women suffering spontaneous early pregnancy loss.
(20/1909)
The purpose of this study was to investigate, quantify and compare the expression of activation markers by decidual leukocytes in sporadic spontaneous early pregnancy loss and apparently normal first trimester human pregnancy. Decidua was obtained from 18 therapeutic abortions and 20 sporadic spontaneous abortions at 8-12 weeks gestational age. Cryostat sections were labelled by the avidin-biotin complex-peroxidase method using monoclonal antibodies specific for CD45, CD56, CD3, human leukocyte antigen (HLA) DR, CD69, CD25 and very late antigen (VLA)1. Positive cells were quantified and the results were analysed using the Mann-Whitney statistical test. Significantly increased numbers of CD69-positive and CD25-positive cells were detected in spontaneous abortion decidua, when compared with therapeutic abortion decidua. Approximately 50% of women experiencing spontaneous miscarriage also contained significantly elevated numbers of HLA DR-positive cells within decidua. Double immunohistochemical labelling studies demonstrated that the CD25-positive and CD69-positive cells in spontaneous abortion decidua were CD3-positive T cells rather than CD56-positive granulated lymphocytes. Immunological dysfunction within endometrium may account for a proportion of sporadic spontaneous abortions. (+info)
The conservative management of first trimester miscarriages and the use of colour Doppler sonography for patient selection.
(21/1909)
This study of patients with first trimester miscarriage evaluates whether conservative management is a feasible strategy and assesses the value of colour Doppler ultrasonography for patient selection. After confirmation of the diagnosis by transvaginal sonography all patients were offered the choice of immediate dilatation and curettage or conservative management. The presence of a gestational sac, the occurrence of spontaneous complete miscarriage within 28 days, detectable pulsatile blood flow within the placenta in the presumed region of the intervillous space and post-treatment complications were the main end-points. Out of a total of 108 women recruited, 23 (21.3%) elected to undergo immediate dilatation and curettage and 85 (78.7%) chose conservative management. The treatment groups were similar in age, gestational age, gestational sac diameter, serum concentrations of human chorionic gonadotrophin (HCG) and progesterone, and proportion of patients who had post-treatment complications (12-13%). Of patients in the conservative management group, 71 out of 85 (84%) had a spontaneous, complete abortion, while 37 out of 46 cases (80%) with detectable presumed intervillous pulsatile blood flow had a complete, spontaneous abortion within 1 week; this occurred in 23% of cases with no detectable flow. This suggests that conservative management is a successful approach for many patients with first trimester miscarriage; colour Doppler ultrasonography can be used to select the most suitable patients for this strategy, and thus reduce the need for hospital admission and surgery. (+info)
Normal pregnancy outcome after inadvertent exposure to long-acting gonadotrophin-releasing hormone agonist in early pregnancy.
(22/1909)
Five infertile women exposed to long-acting gonadotrophin-releasing hormone agonist (GnRHa) during early pregnancy were studied to assess the risks of embryotoxicity on the outcome of their pregnancies. All the patients were diagnosed as stage 3-4 endometriosis following laparoscopy. Long-acting GnRHa (3.75 mg) was given in the first 3 days of their preceding menstrual period. Four of the five patients had two GnRHa injections and the last patient had three GnRHa injections. All patients were advised to use a barrier contraception (condoms) throughout the treatment period. Since all complained of no bleeding following the initial injections, human chorionic gonadotrophin (beta-HCG) concentrations were tested in order to rule out any pregnancy. Ultrasonographic examinations were commenced routinely and all patients had amniocentesis at 16-18 weeks gestational age. Genetic analysis revealed a normal karyotype in all fetuses. All five pregnancies progressed to term without complication, and normal healthy infants were delivered. Although there are still no clear answers concerning teratogenic and hormonal effects of GnRHa exposure in pregnancy, our data may suggest that luteal function, genetic structure and pregnancy outcome are not adversely affected by GnRHa. Since possible subtle effects on fetal endocrine organs cannot be disregarded, close monitoring is still needed in GnRHa-exposed pregnancies. (+info)
A screening program for trisomy 21 at 10-14 weeks using fetal nuchal translucency, maternal serum free beta-human chorionic gonadotropin and pregnancy-associated plasma protein-A.
(23/1909)
OBJECTIVE: To examine the potential impact of combining maternal age with fetal nuchal translucency thickness and maternal serum free beta-human chorionic gonadotropin (beta-hCG) and pregnancy-associated plasma protein-A (PAPP-A) in screening for trisomy 21 at 10-14 weeks of gestation. METHODS: Maternal serum free beta-hCG and PAPP-A were measured by Kryptor, a random access immunoassay analyzer using time-resolved amplified cryptate emission, in 210 singleton pregnancies with trisomy 21 and 946 chromosomally normal controls, matched for maternal age, gestation and sample storage time. In all cases the fetal crown-rump length and nuchal translucency thickness had been measured by ultrasonography at 10-14 weeks of gestation and maternal blood had been obtained at the time of the scan. The distributions (in multiples of the median; MoM) of free beta-hCG and PAPP-A (corrected for maternal weight) and fetal nuchal translucency (NT) were determined in the trisomy 21 group and the controls. Likelihood ratios for the various marker combinations were calculated and these were used together with the age-related risk for trisomy 21 in the first trimester to calculate the expected detection rate of affected pregnancies, at a fixed false-positive rate, in a population with the maternal age distribution of pregnancies in England and Wales. RESULTS: In a population with the maternal age distribution of pregnancies in England and Wales, it was estimated that, using the combination of maternal age, fetal nuchal translucency thickness and maternal serum free beta-hCG and PAPP-A, the detection of trisomy 21 pregnancies would be 89% at a fixed false-positive rate of 5%. Alternatively, at a fixed detection rate of 70%, the false-positive rate would be 1%. The inclusion of biochemical parameters added an additional 16% to the detection rate obtained using NT and maternal age alone. CONCLUSIONS: Rapid diagnostic technology like Kryptor, which can provide automated reproducible biochemical measurements within 30 min of obtaining a blood sample, will allow the development of interdisciplinary one-stop clinics for early fetal assessment. Such clinics will be able to deliver improved screening sensitivity, rapidly and more efficiently, leading to reduced patient anxiety and stress. (+info)
Nuchal translucency in fetuses affected by homozygous alpha-thalassemia-1 at 12-13 weeks of gestation.
(24/1909)
OBJECTIVE: Fetuses affected by homozygous alpha-thalassemia-1 are anemic in the first trimester. We studied their nuchal translucency (NT) measurements at 12-13 weeks of gestation. METHODS: Nuchal translucency was measured prospectively in fetuses at risk of homozygous alpha-thalassemia-1. Measurements of those fetuses subsequently confirmed to be affected by homozygous alpha-thalassemia-1 but with a normal karyotype were compared to those of 440 controls. The controls were from the general obstetric population who had NT measurements at 12 or 13 weeks with known normal outcome. All the NT measurements were expressed as multiples of the median (MoM) for the gestational day. RESULTS: Between 1996 and 1998, 94 at-risk pregnancies were studied. Of these, 32 were subsequently confirmed to be affected by homozygous alpha-thalassemia-1. Chromosome study was not carried out in three cases and these were excluded from the analysis. Nuchal translucency MoMs for cases and controls were found to fit a log Gaussian distribution. The log means (standard deviation) for case and control NT MoM were 0.075 (0.156) and -0.0019 (0.091), respectively. The median NT MoM (95% CI) for cases was 1.19 (1.08-1.62) and was significantly higher than that of the controls (p < 0.001). However, there was extensive overlap of NT between cases and controls. CONCLUSION: Overall, there was a 19% increase in NT MoM in fetuses affected by homozygous alpha-thalassemia-1. This represents a difference of only 0.3-0.4 mm, which is clinically insignificant. This finding indirectly suggests that the increased NT in trisomic fetuses cannot be explained by fetal anemia. Conversely, the presence of increased NT in a fetus at risk of homozygous alpha-thalassemia-1 should alert one to the possibility of chromosomal abnormality rather than being attributed to fetal anemia. (+info)