Enhanced S100B expression in T and B lymphocytes in spontaneous preterm birth and preeclampsia.

OBJECTIVES: S100B belongs to the family of danger signaling proteins. It is mainly expressed by glial-specific cells in the brain. However, S100B was also detected in other cell likewise immune cells. This molecule was suggested as biomarker for inflammation and fetal brain damage in spontaneous preterm birth (sPTB), preeclampsia (PE) and HELLP (hemolysis, elevated liver enzymes, and low platelet count). METHODS: The aim of our study was to determine the concentration of S100B in maternal and cord blood (CB) plasma and placenta supernatant as well as the expression of S100B in maternal and CB CD4+ T cells and CD19+ B cells in sPTB and patients delivering following PE/HELLP diagnosis compared to women delivering at term (TD). The S100B expression was further related to the birth weight in our study cohort. RESULTS: S100B concentration was enhanced in maternal and CB plasma of sPTB and PE/HELLP patients and positively correlated with interleukin-6 (IL-6) levels. Increased S100B was also confirmed in CB of small-for-gestational-age (SGA) infants. S100B expression in maternal blood was elevated in CD4+ T cells of PE/HELLP patients and patients who gave birth to SGA newborns as well as in CD19+ B cells of sPTB and PE/HELLP patients and patients with SGA babies. In CB, the expression of S100B was increased in CD19+ B cells of sPTB, PE/HELLP and SGA babies. CONCLUSIONS: Our results support the hypothesis that S100B expression is enhanced in inflammatory events associated with preterm birth and that S100B expression in immune cells is a relevant marker for inflammation during pregnancy complications.

Regulatory B Cells Are Decreased and Impaired in Their Function in Peripheral Maternal Blood in Pre-term Birth.

Preterm birth (PTB) is defined as birth before 37 completed weeks of gestation. The causes of PTB are multiple and complex, the underlying pathophysiology being largely unknown. Interferences in the fine-tuned balance of the maternal immune system have been pointed to as one possible cause of PTB. Regulatory B cells (Breg) are part of the adaptive immune response, and recent data suggest that they may contribute to a healthy pregnancy by their regulatory/suppressive function. We investigated the frequency of Breg cells in peripheral blood of women undergoing PTB and control women immediately before giving birth via cesarean section. We detected an enhanced number of B cells, but a reduced number of Breg cells in women delivering preterm. In addition, the percentage of IL-10-producing B cells was decreased in PTB following stimulation with TLR agonists CpG or LPS, alone or combined with CD40L. This was associated with increased levels of pro-inflammatory cytokines in maternal serum. Moreover, isolated maternal B cells before delivering premature babies secreted higher level of the pro-inflammatory cytokine IL-6. No alterations in the frequency of regulatory T cells were found. Our data indicate that alterations in the number and function of Breg cells in peripheral maternal blood contribute to the immunological changes observed in preterm delivery and suggest these cells as important regulators of maternal immune responses.

Human Miscarriage Is Associated With Dysregulations in Peripheral Blood-Derived Myeloid Dendritic Cell Subsets.

Dendritic cells (DC) are critically involved in decisions related to the acceptance or rejection of the foreign fetal antigens by the maternal immune system. However, particularly for human peripheral blood DCs (PBDC), available literature is rather inconsistent and the factors regulating these cells are ill-defined. Here, we investigated the phenotype and functionality of different human PBDC subsets during normal and pathologic pregnancies and studied an involvement of human chorionic gonadotropin (hCG) in PBDC regulation. Peripheral blood samples were obtained from normal pregnant women in all three trimesters, from first trimester miscarriage patients and from healthy non-pregnant women. Samples were analyzed for plasma hCG levels, for regulatory T (Treg) cell numbers, for frequencies of total and mature plasmacytoid (PDC) and myeloid (MDC1 and MDC2) PBDC subsets and for their cytokine secretion. In vitro assays, culturing PDC, MDC1 or MDC2 in the presence of two trophoblast cell lines, placenta explant supernatants or two hCG preparations were performed. The Treg-inducing capability of hCG- or non-hCG-treated stimulated MDC1 was assessed. Total and mature MDC1 and MDC2 frequencies increased during the first and second trimester of normal pregnancy, respectively. Miscarriage was associated with a reduced MDC1 and an increased MDC2 activation profile. PDC were not altered neither during normal pregnancy progression nor during miscarriage. In vitro, the culture of isolated PBDC subsets in the presence of placenta-derived factors impaired the maturation of MDC1 and differentially affected PDC maturation. An inhibitory effect on MDC1 and PDC maturation was also proven for the urine-derived hCG preparation. Finally, we observed a Treg cell elevation during early normal pregnancy that was not present in miscarriages. Stimulated MDC1 induced Treg cells in vitro, however, hCG was not involved in this process. Our findings suggest that during normal pregnancy PBDC subsets are differentially regulated dependent on gestational age. Miscarriage seems to be associated with dysregulations in the myeloid PBDC subsets and with disturbances in Treg cell frequencies. Moreover, our results propose an interdependency between MDC1 and Treg cells during early pregnancy. hCG, although shown to impair MDC1 maturation, does not seem to be a key regulator of PBDC alterations during pregnancy.

Human Umbilical Vein Endothelial Cells foster conversion of CD4+CD25-Foxp3- T cells into CD4+Foxp3+ Regulatory T Cells via Transforming Growth Factor-ß.

Trans-placental cell trafficking is a naturally occurring process during pregnancy that results in the direct recognition of foreign maternal antigens by fetal tissue and vice versa. Immigration of potentially harmful allo-reactive maternal T cells into fetal circulation may provoke anti-fetal immune responses. However, the contact with fetal tissue may favor differentiation of maternal immune cells into cells with a regulatory phenotype. Human Umbilical Vein Endothelial Cells (HUVECs) possess immune-regulating properties and are one of the first fetal cells to get in contact with foreign maternal immune cells. Therefore, here we studied whether HUVECs induce the conversion of maternal T cells into regulatory T (Treg) cells. Moreover, we assessed whether this response is changing according to the sex of the HUVECs. Both female and male HUVECs induced the conversion of maternal T cells into Treg cells which is partially mediated via TGF-ß. Female HUVECs showed a stronger capacity to induce Treg cells compared to male HUVECs. Our findings propose that HUVECs contribute to fetal-maternal tolerance by the increase of the Treg cell population. Sex-specific differences in Treg cell induction may partly account for the disparities on the incidence of infectious and autoimmune diseases between both sexes during early childhood.

JEG-3 Trophoblast Cells Producing Human Chorionic Gonadotropin Promote Conversion of Human CD4+FOXP3- T Cells into CD4+FOXP3+ Regulatory T Cells and Foster T Cell Suppressive Activity.

The pregnancy hormone human Chorionic Gonadotropin (hCG) reportedly modulates innate and adaptive immune responses and contributes thereby to fetal survival. More precisely, hCG has been shown to support human Treg cell homing into the fetal-maternal interface and enhance number and function of Treg cells in murine pregnancy. Here, we aimed to study whether hCG and hCG-producing human trophoblast cell lines induce Treg cells from CD4+FOXP3- T cells and promote T cell suppressive activity. CD4+FOXP3- T cells were isolated from peripheral blood of normal pregnant women and cultured in the presence of hCG-producing (JEG-3, HTR-8) and non-producing (SWAN-71) cell lines. To confirm the participation of hCG in Treg cell conversion, the experiments were performed in the presence of anti-hCG and additional experiments were run with recombinant or urine-purified hCG. After culture the number of CD4+FOXP3+ Treg cells as well as the suppressive capacity of total T cells was assessed. hCG-producing JEG-3 cells as well as recombinant and urine-purified hCG induced CD4+FOXP3+ Treg cells from CD4+FOXP3- T cells. Blockage of hCG impaired Treg cell induction. Moreover, hCG-producing JEG-3 cells increased suppressive activity of CD4+FOXP3- T cells through an antigen-independent pathway. Our results propose another mechanism through which hCG modulates the female immune system during pregnancy in favor of the fetus.