Anti-fetal immune response mechanisms may be involved in the pathogenesis of placental abruption

An analysis of placental chorionic villous and decidual basalis tissue immunoreactivity in patients after cesarean section due to a placenta accreta spectrum disorder and elective cesarean section followed by the depressed mood

An analysis of placental chorionic villous and decidual basalis tissue immunoreactivity in patients after cesarean section due to a placenta accreta spectrum disorder and elective cesarean section followed by a depressed mood.

RESEARCH BACKGROUND

Over the past few years, interest in investigating immune dysfunction in patients with psychiatric disorders has increased. B7-H4 is a molecule with immunosuppressive properties that seems to play a key role in establishing maternal tolerance against fetal antigens. The aim of this study was to compare the B7-H4 immunoreactivity levels in patients after cesarean section.

METHODS

Placental and decidual tissue samples were obtained from 49 women who delivered at Bielański Hospital in Warsaw between 2009 and 2015. Fifteen of the patients developed postpartum depression and 14 had a diagnosis of placenta accreta spectrum. The control group consisted of 20 healthy patients on whom cesarean section was performed due to breech presentation at term.

RESULTS

The highest levels of B7-H4 immunoreactivity were found in the placental chorionic villous and decidual basalis tissue samples of the patients who later developed postpartum depression, while the lowest levels were found in the samples of those patients with a placenta accreta spectrum disorder. The difference between the B7-H4 immunoreactivity levels of these two groups was statistically significant. The B7-H4 expression levels were statistically significantly higher in the women in the postpartum depression group than in the control group.

CONCLUSION

Postpartum depression follows a disturbance of the suppressive milieu responsible for rebalancing the maternal immune system after the initial cytotoxic activation during labor.

Cytokine see-saw across pregnancy, its related complexities and consequences

During pregnancy, a woman's immune system adapts to the changing hormonal concentrations, causing immunologic transition. These immunologic changes are required for a full-term pregnancy, preserving the fetus' innate and adaptive immunity. Preterm labor, miscarriage, gestational diabetes mellitus, and pre-eclampsia are all caused by abnormal cytokine expression during pregnancy and childbirth. A disruption in the cytokine balance can lead to autoimmune diseases or microbiologic infections, or to autoimmune illness remission during pregnancy with postpartum recurrence. The cytokine treatments are essential and damaging to the developing fetus. The current review summarizes the known research on cytokine changes during pregnancy and their possible consequences for pregnant women. Studies suggest that customizing medication for each woman and her progesterone levels should be based on the cytokine profile of each pregnant woman. Immune cells and chemicals play an important function in development of the placenta and embryo. During pregnancy, T cells divide and move, and a careful balance between proinflammatory and anti-inflammatory cytokines is necessary. The present review focuses on the mother's endurance in generating fetal cells and the immunologic mechanism involved.

Expression of the Costimulatory Molecule B7-H4 in the Decidua and Placental Tissues in Patients with Placental Abruption

B7 homolog 4 protein (B7-H4), a member of the B7 family, is a immunomodulatory membrane protein. The aim of the study was to evaluate the expression of this protein in the decidua and placental tissues in case of placental abruption (PA) compared to cases of retained placental tissue (RPT) and controls. Tissue samples were obtained from 47 patients with PA, 60 patients with RPT, and 41 healthy controls. The samples were stained for B7-H4 expression, analyzed by an expert pathologist, and a semi-quantitative scale was applied. A statistical analysis revealed that the expression of B7-H4 was significantly higher in the decidua in PA samples compared to samples from patients with RPT (p-value < 0.001) and healthy controls (p-value < 0.001). The expression of B7-H4 in the placental chorionic villus was significantly higher in PA samples in relation to samples from healthy controls (p-value < 0.001) but not in relation to RPT samples (p-value = 0.0853). This finding suggests that B7-H4 might play an important role in mechanisms restoring reproductive tract homeostasis. Further research is necessary in regard to the role of B7-H4 in PA.

Evaluation of carcinoembryonic antigen-related cell adhesion molecule 1 blood serum levels in women at high risk for preeclampsia

PROBLEM

The aim of this study was to evaluate the sCEACAM1 concentrations in serum from patients in the first trimester who have a high risk for developing PE during pregnancy.

METHOD OF THE STUDY

Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) levels were determined with ELISA. The patients (n = 109) were divided into two groups: patients who have a high risk of developing PE early-onset and a control group. Patients who have a high risk of developing PE were then divided into two subgroups depending on PE development in third trimester of pregnancy: PE in third trimester versus no PE in third trimester.

RESULTS

sCEACAM1 concentrations in patients who were screened as having a high risk for developing PE were significantly higher than in healthy pregnant women in the first trimester (p = .03). The highest sCEACAM1 concentration was found in the high-risk group with PE development compared to the control group (p = .004).

CONCLUSION

Elevated sCEACAM1 blood serum levels in women with PE suggest that there is immune dysregulation in early pregnancy, which may be helpful in PE prediction and therapy.

Circulating Levels of Pregnancy-Associated, Placenta-Specific microRNAs in Pregnant Women With Placental Abruption

The aim of this study was to clarify the association between circulating pregnancy-associated, placenta-specific microRNAs (miRNAs) in maternal plasma and placental abruption. All samples were obtained after receiving written informed consent, and the study protocol was approved by the institutional review board. Maternal blood samples (7 mL) were obtained at 25 to 40 weeks of gestation from 15 cases of placental abruption (placental abruption group) and from 24 cases of uncomplicated pregnancies (uncomplicated pregnancy group). The plasma concentrations of pregnancy-associated, placenta-specific miRNAs (miR-515-3p, -517a, -517c, and -518b) were measured by quantitative real-time reverse transcription-polymerase chain reaction. There were no significant differences in clinical characteristics between the 2 groups. The median concentration of plasma cell-free miR-517c in the placental abruption group was 21 672.2 copies/mL, whereas that in the uncomplicated pregnancy group was 13 452.0 copies/mL (Mann-Whitney U test, P = .047). Receiver operating characteristic curve analysis revealed that plasma cell-free miR-517c levels discriminated placental abruption from uncomplicated pregnancy with an area under the curve of 0.692. When a cutoff negative/positive value of 15 669.6 copies/mL was selected, the sensitivity and specificity were 73.3% and 62.5%, respectively. In addition, the positive and negative predictive values were 55.0% and 78.9%, respectively. Plasma cell-free miR-517a and miR-517c levels in the large abruption (degree of abruption ≥50% of placenta) group were significantly higher than in the small abruption (<50%) group ( P = .03 for both miRNAs). In conclusion, the circulating level of cell-free miR-517c in maternal plasma was increased as a consequence of placental abruption and may be a potential biomedical marker for placental abruption.

Changes in the Blood Serum Levels of the Costimulatory Soluble B7-H4 Molecule in Pregnant Women During the Peripartal Phase

PROBLEM

B7-H4, a transmembrane protein that negatively regulates T lymphocytes, seems to play a role in the suppression of the im\mune response at the maternal-fetal interface. The aim of this study was to compare the blood serum concentration levels of soluble B7-H4 (sB7-H4) prepartal and postpartal in both women who experienced spontaneous onset of labor and those who underwent elective cesarian section.

METHOD OF STUDY

Blood was obtained from 30 prepartal and postpartal women who delivered at the University Hospital of Essen between 2011 and 2012. These patients were further divided into two subgroups depending on the advancement of labor. The sB7-H4 blood serum concentration levels of the women in the groups were then determined by ELISA (BIOZOL, Eching, Germany).

RESULTS

In women who underwent elective cesarian section, a significant increase in sB7-H4 blood serum concentration levels occurred postpartal, while in women who experienced spontaneous onset of labor, no differences between prepartal and postpartal concentration levels were observed. The sB7-H4 blood serum concentration levels on the day after delivery in the women who experienced spontaneous labor and those who underwent elective cesarian section were comparable; however, higher blood serum concentration levels of sB7-H4 were observed prepartal in women with spontaneous onset of labor compared to those found in the women about to undergo elective cesarian section.

CONCLUSION

These changes in sB7-H4 blood serum concentration levels suggest that this protein is involved in immunological changes associated with the spontaneous onset of labor and post-delivery homeostasis.

Beneficial or harmful effect of antipaternal human leukocyte antibodies on pregnancy outcome? A systematic review and meta-analysis

PROBLEM

During pregnancy, antibodies are induced that target the paternal human leukocyte antigens of the semi-allogeneic fetus. The level and presence of these antibodies have been reported increased as well as decreased for a variety of pregnancy complications; the clinical relevance and consequences of these antibodies are not very clear. Therefore, the objective of this review is to determine whether the presence of antipaternal antibodies influences pregnancy outcome.

METHOD

We performed a systematic search of studies that described the effect of antipaternal antibodies on pregnancy complications. The primary outcome was the risk ratio for HLA class I and class II antibodies on pregnancy complications. Furthermore, we calculated the risk for first- and third-trimester complications.

RESULTS

The seventeen studies that were selected for meta-analysis showed high level of statistical and clinical heterogeneity. In the meta-analysis, we found no significant effect of HLA class I or class II antibodies on pregnancy outcome.

CONCLUSION

No consistent conclusions can be drawn from the meta-analysis. Discrepancies in the meta-analysis are the result of different screening techniques, varying time points of screening, and use of incorrect control groups. Furthermore, more detailed analyses of the characteristics and specificity of the antibodies involved are essential.

To B or not to B cells-mediate a healthy start to life

Maternal immune responses during pregnancy are critical in programming the future health of a newborn. The maternal immune system is required to accommodate fetal immune tolerance as well as to provide a protective defence against infections for the immunocompromised mother and her baby during gestation and lactation. Natural immunity and antibody production by maternal B cells play a significant role in providing such immunoprotection. However, aberrations in the B cell compartment as a consequence of maternal autoimmunity can pose serious risks to both the mother and her baby. Despite their potential implication in shaping pregnancy outcomes, the role of B cells in human pregnancy has been poorly studied. This review focuses on the role of B cells and the implications of B cell depletion therapy in pregnancy. It highlights the evidence of an association between aberrant B cell compartment and obstetric conditions. It also alludes to the potential mechanisms that amplify these B cell aberrances and thereby contribute to exacerbation of some maternal autoimmune conditions and poor neonatal outcomes. Clinical and experimental evidence suggests strongly that maternal autoantibodies contribute directly to the pathologies of obstetric and neonatal conditions that have significant implications for the lifelong health of a newborn. The evidence for clinical benefit and safety of B cell depletion therapies in pregnancy is reviewed, and an argument is mounted for further clinical evaluation of B cell-targeted therapies in high-risk pregnancy, with an emphasis on improving neonatal outcomes and prevention of neonatal conditions such as congenital heart block and fetal/neonatal alloimmune thrombocytopenia.

The presence of HLA-antibodies in recurrent miscarriage patients is associated with a reduced chance of a live birth

Anti-paternal HLA-antibodies are considered a harmless phenomenon during most pregnancies, whereas their role in recurrent miscarriage (RM) patients is disputed. In contrast to primary RM, patients with secondary RM have carried a fetus to term pregnancy prior to a series of miscarriages, which increases the chance that allogeneic fetal cells appear in the maternal circulation. This study investigates the frequency of HLA-antibodies in secondary RM, primary RM patients and parous controls and analyzes whether the presence of HLA-antibodies in early pregnancy is associated with pregnancy outcome. Sera from women with secondary RM (n=56), primary RM (n=13) and parous controls (n=24) were tested for HLA-antibodies using an ELISA assay and complement dependent cytotoxicity. Samples were taken at gestational week 4-5 in 62 (90%) of the patients. HLA-antibodies were significantly more frequent in secondary RM patients with a boy prior to the miscarriages (62%) compared to secondary RM patients with a firstborn girl (29%, p=0.03), primary RM patients (23%, p=0.02) and parous controls (25%, p=0.005). Forty-one percent of HLA-antibody positive pregnant RM patients had a live birth compared to 76% of HLA-antibody negative RM patients, p=0.006 (adjusted OR: 0.22 (0.07-0.68), p=0.008). In conclusion, HLA-antibodies are significantly more frequent in secondary RM patients with a firstborn boy than in other RM patients and controls. The presence of these antibodies in early pregnancy is associated with a reduced chance of a live birth. Further exploring this association may increase our understanding of maternal acceptance of the fetal allograft.

Secondary recurrent miscarriage and H-Y immunity

BACKGROUND

Approximately half recurrent miscarriage (RM) cases remain unexplained after standard investigations. Secondary RM (SRM) is, in contrast to primary RM, preceded by a birth, which increases the transfer of fetal cells into the maternal circulation. Mothers of boys are often immunized against male-specific minor histocompatibility (H-Y) antigens, and H-Y immunity can cause graft-versus-host disease after stem-cell transplantation. We proposed the H-Y hypothesis that aberrant H-Y immunity is a causal factor for SRM.

METHODS

This is a critical review of the H-Y hypothesis based on own publications and papers identified by systematic PubMed and EMBASE searches.

RESULTS

SRM is more common after the birth of a boy and the subsequent live birth rate is reduced for SRM patients with a firstborn boy. The male:female ratio of children born prior and subsequent to SRM is 1.49 and 0.76 respectively. Maternal carriage of HLA-class II alleles presenting H-Y antigens to immune cells is associated with a reduced live birth rate and increased risk of obstetric complications in surviving pregnancies in SRM patients with a firstborn boy. In early pregnancy, both antibodies against HLA and H-Y antigens are increased in SRM patients compared with controls. Presence of these antibodies in early pregnancy is associated with a lower live birth rate and a low male:female ratio in subsequent live births, respectively. Births of boys are also associated with subsequent obstetric complications in the background population.

CONCLUSIONS

Epidemiological, immunogenetic and immunological studies support the hypothesis that aberrant maternal H-Y immune responses have a pathogenic role in SRM.

Longitudinal modulation of immune system cytokine profile during pregnancy

OBJECTIVE

To characterize immune modulation as expressed by cytokine assays at three time-points in human pregnancy.

STUDY DESIGN

This is a prospective, longitudinal study of a broad panel of cytokine expression during singleton pregnancies resulting in an uncomplicated, full-term, live births. Peripheral blood was obtained at 8-14, 18-22, and 28-32 weeks gestation. Six cytokines - IFN-γ, IL-4, TNF-α, IL-1β, IL-6, and IL-10 - were measured in supernatants obtained from whole blood stimulations with PHA or LPS and were compared to unstimulated controls. Samples were processed by Luminex-100 MAP®. We used Generalized Linear Models (GLM) to evaluate cytokine trajectories.

RESULTS

Complete data were obtained for 45 uncomplicated pregnancies. Overall, peripheral blood WBC's demonstrated dampened cytokine responses. However, over the course of pregnancy, we found enhanced counter-regulatory cytokine expression (e.g., shown by increased IL-10).

CONCLUSION

The overall decrease in pro-inflammatory cytokines and increase in counter-regulatory cytokines as uncomplicated pregnancy progresses supports the evolving concepts of immunoregulation for the maintenance of a viable pregnancy.

Pre-eclampsia, placental abruption and increased risk of atopic sensitization in male adolescent offspring

PROBLEM

The aim of this study was to investigate maternal pre-eclampsia (PE), placental abruption (PA) and atopy among offspring.

METHOD OF STUDY

Obstetric data was recorded from 378 women who were included into the Caesarean delivery birth cohort during 1990-1992. When their children were 15-17 years old skin prick tests (SPTs) and inhalant allergen-specific (IAS) immunoglobulin E (IgE) were determined among offspring.

RESULTS

Adolescents whose mothers had either PE or PA at the time of delivery had more atopy and especially more severe atopy as measured by the incidence of SPTs positive for > or = 5 allergens (RR: 4.28, 95% CI: 1.54-11.92; P < 0.005) and elevated IAS IgE levels (> or = 1.0 kU/L) (RR: 4.27, 95% CI: 1.08-16.99; P < 0.039). This increased risk was particularly observed in male adolescents.

CONCLUSION

Maternal PE and PA were associated with an increased risk of severe atopy, especially in male adolescent offspring.

Functional changes of human peripheral B-lymphocytes in pre-eclampsia

PROBLEM

The aim of our study was to investigate the functional changes of human peripheral B-lymphocytes in healthy and pre-eclamptic pregnancies.

METHOD OF STUDY

Twenty patients with pre-eclampsia and 15 healthy third-trimester pregnant women were recruited in this study. Peripheral blood mononuclear cells (PBMCs) were isolated and directly stained with fluorescein isothiocyanate (FITC)-labeled anti-CD27 monoclonal antibody (mAb) and phycoerythrin (PE)-labeled anti-CD38 mAb. The percentages of the individual B-cell subsets were estimated out of total lymphocytes by flow cytometric analysis. Additionally, the enriched PBMCs were cultured with or without the stimulation of pokeweed mitogen (PWM) for 5 days. Then morphologic observation of plasma cells was analysed by Wright-Giemsa stain, and antibody-producing cells were detected by enzyme-linked immunospot assay.

RESULTS

The percentage of CD27(-)CD38(-) naïve B-cells and CD27(-)CD38(+) plasma cells did not differ between study groups (P > 0.05). The percentage of CD27(+)CD38(-) memory B-cells and CD27(+)CD38(+) plasma cell precursors increased in pre-eclamptic women compared with the controls (P < 0.05). Irrespective of whether the PBMCs were stimulated with or w/o PWM in vitro, the mean percentages of generated plasma cells were significantly higher in pre-eclamptic group than in the controls (P < 0.05). There were more antibody-producing cells in pre-eclamptic women following the activation of PWM than those in the controls (P < 0.01).

CONCLUSION

Our findings implicate that the functional changes of human circulating B-cells might contribute to the etiology of pre-eclampsia.

Disseminated intravascular coagulation in obstetric disorders and its acute haematological management

As activation of the coagulation pathway is a physiological response to injury, the development of disseminated intravascular coagulation (DIC) is a warning signal to the clinician that the primary pathological disease state is decompensating. In pregnancy, DIC can occur in several settings, which include emergencies such as placental abruption and amniotic fluid embolism as well as complications such as pre-eclampsia. Whilst the acuteness of the event and the proportionality in the coagulant and fibrinolytic responses may vary between these different conditions, a common theme for pregnancy-associated DIC is the pivotal role played by the placenta. Removal of the placenta is the linchpin to treatment in most cases but appropriate blood product support is also key to management. This is necessary because DIC itself can have pathological consequences that translate clinically into a worse prognosis for affected patients. This article will describe how pregnancy-associated DIC can be diagnosed promptly and how treatment should be managed strategically. It also discusses the latest developments in our understanding of haemostatic mechanisms within the placenta and how these may have relevance to new diagnostic approaches as well as novel therapeutic modalities.

RCAS1 decidual immunoreactivity during placental abruption: immune cell presence and activity

PROBLEM

RCAS1 is a protein responsible for the suppression of cytotoxic immune response during gestation. The present study evaluates the immunoreactivity level of RCAS1 with respect to immune cell status during placental abruption (PA) and retained placental tissue (RPT).

METHOD OF STUDY

RCAS1, CD3, CD56, CD69 and CD25 immunoreactivity was assessed by immunohistochemistry in 66 decidual samples derived from PA and from RPT.

RESULTS

RCAS1 immunoreactivity was statistically significantly higher in decidual tissue samples derived from patients with RPT than in those derived from patients with PA. A statistically significantly lower number of CD56(+) and CD3(+) cells and immunoreactivity level of CD69 were found in patients with RPT, compared to those with PA.

CONCLUSION

Placental abruption seems to be associated with excessive accumulation and activity of CD3(+) and CD56(+) cells in decidua, which processes might, in turn, result from an insufficient RCAS1 decidual level.

Early detection of decreased soluble HLA-G levels in the maternal circulation predicts the occurrence of preeclampsia and intrauterine growth retardation during further course of pregnancy

PROBLEM

Soluble (s) HLA-G1/G5 molecules may potentially affect immune homeostasis during pregnancy. The aim of this study was to determine changes of sHLA-G1/G5 plasma levels throughout normal pregnancy and to assess its predictive value for the occurrence of characteristic gestation-associated diseases during further course of pregnancy.

METHOD OF STUDY

sHLA-G1/G5 levels were estimated in plasma samples of 40 non-pregnant women, 291 women throughout normal pregnancy and 236 women affected by different complications.

RESULTS

In comparison with non-pregnant women sHLA-G1/G5 levels strongly increased during the first trimenon and then decreased continuously toward term. Non-parametric discriminant analysis showed that women with significantly decreased sHLA-G1/G5 levels in the second trimenon had an increased risk of developing preeclampsia and/or intrauterine growth retardation (IUGR) during further course of pregnancy. However, in the third trimenon, sHLA-G1/G5 levels in affected women did not deviate significantly from those of non-affected women. Surprisingly, significantly increased sHLA-G1/G5 levels were detected in third trimenon women with uncontrollable preterm labor, but not in women with prolonged preterm rupture of fetal membranes.

CONCLUSION

For the identification of women with an increased risk of IUGR and/or preeclampsia, measurement of sHLA-G1/G5 plasma levels may be a powerful new tool in prenatal diagnostics.

Indications of anti-HY immunity in recurrent placental abruption

PROBLEM

Placental abruption is a potential life-threatening condition for both the fetus and the mother, being significantly more common in pregnancies with male fetuses. The pathogenesis of placental abruption remains unknown. However, some recent reports point toward a maternal immune response against the fetus as a possible mechanism. No data exist concerning special characteristics of patients suffering recurrent placental abruptions.

METHOD OF STUDY

Identification of all patients with recurrent placental abruption in a retrospective review of 881 consecutive Caucasian women seen in our tertiary centre for recurrent pregnancy losses between 1986 and 2005. The HLA, DRB1, DRB3, 4, 5 and DQB1 genotypes of patients were compared with relevant controls.

RESULTS

Eight patients were identified with recurrent placental abruption. The patients had a total of 22 abruptions; 18 (82%) in which the fetus died. Seven patients (88%) had first-born boys, and 15 abruptions (68%) involved male fetuses. All patients with a first-born boy, except one, had HLA-class II alleles known to restrict CD4+ T-cell responses against male-specific minor histocompatibility (HY)-antigens (HLA-DRB1*15, HLA-DRB3*0301 and HLA-DQB1*05). Haplotypes with these HLA-alleles constituted 64% of the patients' haplotypes compared to 28% of those of the controls (p=0.009). Furthermore, 43% of the patients were homozygous for these haplotypes compared to 5% of controls (p=0.023).

CONCLUSION

We have found that recurrent placental abruption is exclusively almost preceded by the birth of a boy and the majority of patients have HLA-class II known to restrict CD4 T-cell reactions against HY-antigens. This indicates that maternal immunological responses against HY-antigens play a role in recurrent placental abruption.

The presence of gestational diabetes is associated with increased detection of anti-HLA-class II antibodies in the maternal circulation

PROBLEM

Gestational diabetes (GD) may be associated with temporarily reduced immune tolerance toward alloantigens for the time of pregnancy. The aim of this study was to assess anti-HLA-class I and -II antibodies as markers for an aberrant immunostimulation in women with GD.

METHOD OF STUDY

The percentage of anti-HLA-class I and -II antibodies was estimated in women with GD, normal term delivery and fetal distress, which was confirmed by demonstrating low cord blood pH for this patient group. These antibodies may cross the placental barrier and cause interleukin-6 (IL-6) release from fetal monocytes by cross-linking monocytes with antibody-loaded cells. Therefore we estimated the percentage of IL-6-positive monocytes in the fetal circulation of these three patient groups.

RESULTS

We found a significantly increased percentage of anti-HLA-class II in the circulation of women with GD. In comparison with women with normal term delivery, a significantly increased percentage of IL-6-positive monocytes was detected for women with GD and for women with fetal distress. Significantly decreased cord blood pH were detected for neonates born in the presence of fetal distress but not for neonates born in the presence of GD.

CONCLUSIONS

Our results suggest that GD is associated with an increased humoral immune response against HLA-class II antigens.

Placental Abruption in Term and Preterm Gestations

OBJECTIVE

To estimate the magnitude of associations of acute and chronic processes with abruption in preterm and term gestations.

METHODS

A retrospective cohort study was performed using data on women that delivered singleton live births and stillbirths at 20 or more weeks of gestation in the United States, 1995-2002 (n = 30,378,902). Rates of 1) acute-inflammation-associated clinical conditions (premature rupture of membranes and intrauterine infection); 2) chronic processes associated with vascular dysfunction or chronic inflammation (chronic and pregnancy-induced hypertension, preexisting or gestational diabetes, small for gestational age, and maternal smoking); and 3) both acute and chronic processes, were examined among women with and without abruption. Rates were examined separately among preterm (< 37 weeks) and term births, with adjustment for confounders. Relative risk (RR) for aforementioned groups in relation to abruption was derived from multivariate logistic regression models after adjusting for potential confounders.

RESULTS

At preterm gestation, the rates of acute-inflammation-associated conditions were higher among women with than without abruption (12.0% compared with 10.2%; RR 1.38, 95% confidence interval [CI] 1.34-1.42). At term, acute-inflammation-associated conditions were present in 4.2% and 3.3% of births with and without abruption, respectively (RR 1.39, 95% CI 1.33-1.45). At preterm gestation, the rates of chronic processes were 43.9% and 30.0% among women with and without abruption, respectively (RR 1.87, 95% CI 1.85-1.90). At term, the corresponding rates of chronic processes were 41.0% and 22.7%, respectively (RR 2.37, 95% CI 2.34-2.41). Association between both acute and chronic processes and abruption are similar to those of acute-inflammation-associated conditions.

CONCLUSION

Among women with placental abruption, conditions associated with acute inflammation are more prevalent at preterm than term gestations, whereas chronic processes are present throughout gestation.

LEVEL OF EVIDENCE

II-2.

Prolonged preterm rupture of fetal membranes, a consequence of an increased maternal anti-fetal T cell responsiveness

A fetus, although semi-allogeneic, is usually accepted by the maternal immune system. However, complications, including alloresponsive mechanisms, are thought to be potentially detrimental for a successful pregnancy. Therefore, we compared allogeneic T cell responses of nonpregnant women with the response of healthy pregnant women and pregnant women who have various gestation-associated diseases. Peripheral blood mononuclear cells (PBMCs) of all three groups were stimulated with PBMCs from unrelated volunteers. Pregnant women had significantly reduced stimulation indices (SIs) compared with nonpregnant women. Exposing PBMCs from pregnant women to PBMCs of their own fetus led to a further significant decrease of SIs. Among the two groups of pregnant individuals, SIs of women with prolonged preterm rupture of fetal membranes (PPROM) were significantly higher when the maternal PBMCs were stimulated with PBMCs of their own fetus. This phenomenon could not be observed after stimulation with PBMCs from unrelated volunteers. In addition, an increased humoral immune response was assessed for women with PPROM in comparison with women with uncontrollable preterm labor. Our results revealed a strongly reduced allogeneic T cell response of PBMCs from pregnant women that was further down-regulated when PBMCs from their own fetus were used as stimulators. By contrast, data from women with PPROM suggest an increased maternal T cell response specifically toward the fetal HLA antigens.