Regulation of costimulatory signal in maternal-fetal immune tolerance

The regulation of tolerogenic dendritic cells by a Chinese herb formula improves abortion prone in mice

BACKGROUND

Abortion prone (AP) is a common clinical event. The underlying mechanism remains unclear. Traditional Chinese formulas are known to be efficient in the management of abortion. The purpose of this study is to observe the effects of Anzitiaochongtang (AZT), a traditional formulation of Chinese medicine, on improving AP in mice by regulating immune tolerance.

METHODS

An established abortion model (CBA/J×DBA/2) was employed. AZT was prepared and administered to mice in a manner consistent with clinical practice. Tolerogenic dendritic cells (tDC) and type 1 regulatory T cells (Tr1 cell) in mice were analyzed by immunological approaches to be used as representative immune tolerant parameters.

RESULTS

An AP model was established with CBA/J × DBA/2 mice. The expression of IL-10 in tDC and Tr1 cell frequency in the mouse decidua tissues were lower in the AP group than that in the normal pregnancy (NP) group. Administration of AZT up regulated the expression of IL-10 in tDCs and Tr1 cell generation in the decidua tissues, and improved the pregnancy and tissue structure in AP mice. The main mechanism by which AZT improves pregnancy in AP mice is that AZT enhanced the expression of galectin-9 in the epithelial cells of decidua tissues. Galectin 9 activates TIM3 on DCs to promote the IL-10 expression. The DCs induced more Tr1 cells in the decidua tissues.

CONCLUSIONS

Dysfunctional tDCs were detected in the AP decidua tissues. Administration of AZT improved pregnancy in AP mice by regulating tDC function and generation of Tr1 cells in the maternal-fetal interface.

Correlation of peripheral blood and endometrial immunophenotyping in ART: is peripheral blood sampling useful?

PURPOSE

Using a comprehensive flow cytometric panel, simultaneously obtained mid-luteal immunophenotypes from peripheral blood and endometrium were compared and values correlated. Is a peripheral blood evaluation of reproductive immunophenotype status meritorious relative to local endometrial evaluation to directly assess the peri-implantation environment?

METHODS

Fifty-five patients had a mid-luteal biopsy to assess the local endometrial immunophenotype, while simultaneously providing a peripheral blood sample for analysis. Both samples were immediately assessed using a comprehensive multi-parameter panel, and lymphocyte subpopulations were described and compared.

RESULTS

Distinct lymphocyte proportions and percentage differences were noted across the two compartments, confirming the hypothesis that they are distinct environments. The ratio of CD4 + to CD8 + T cells were reversed between the two compartments, as were Th1 and Th2-type CD4 + T cell ratios. Despite these differences, some direct relationships were noted. Positive Pearson correlations were found between the levels of CD57 + expressing natural killer cells, CD3 + NK-T cells and CD4 + Th1 cells in both compartments.

CONCLUSIONS

Flow cytometric evaluation provides a rapid and objective analysis of lymphocyte subpopulations. Endometrial biopsies have become the gold standard technique to assess the uterine immunophenotype in adverse reproductive outcome, but there may still a place for peripheral blood evaluation in this context. The findings demonstrate significant variations in cellular proportions across the two regions, but some positive correlations are present. Immunological assessment of these specific peripheral blood lymphocyte subtypes may provide insight into patients with potential alterations of the uterine immune environment, without the risks and inconveniences associated with an invasive procedure.

Excessive Immune Activation and the Correlation with Decreased Expression of PD-1 at the Maternal-Fetal Interface in Preeclampsia

The etiology of preeclampsia (PE) is still unknown, and excessive immune activation is an important component of its pathogenesis. Programmed cell death protein 1 (PD-1) is one of immune checkpoints which may prevent overactivated immune attack and lead to a tolerant immune microenvironment. Little is known about the involvement of PD-1-mediated immunoregulation at the maternal-fetal interface in PE. To investigate the inflammatory pattern and the involvement of PD-1 in the decidua of women with PE, decidual tissues were obtained from PE and control pregnant women. Quantitative RT-PCR analysis of the mRNA levels of the inflammatory cytokines was performed. PD-1 expression was detected by immunohistochemistry, western blot analysis, and flow cytometry. To prove the role of PD-1, decidual immune cells were incubated with blocking antibodies, and the inflammatory cytokines were detected by ELISA. We observed that the mRNA levels of IL-1β, IL-6, TNF-α, and IFN-γ were higher in the decidua of the PE group than in the decidua of the control group. The mRNA levels of IL-4 and IL-10 were lower in PE. The expression level of PD-1 was significantly downregulated, and the proportion (%) of PD-1 + CD45 + cells was significantly lower in PE. There was a significant linear correlation between PD-1 expression and common proinflammatory cytokines in the decidua. Anti-PD-1 blocking antibody significantly increased the secretion of proinflammatory cytokines. Our data suggested that the inflammatory pattern and decreased PD-1 expression in the decidua might play an active role in the local immunoregulatory mechanisms of PE. The PD-1 pathway in the maternal-fetal interface possibly function to break the tolerant immune microenvironment in PE via inflammatory cytokines.

β3-Adrenoceptors as Putative Regulator of Immune Tolerance in Cancer and Pregnancy

Understanding the mechanisms of immune tolerance is currently one of the most important challenges of scientific research. Pregnancy affects the immune system balance, leading the host to tolerate embryo alloantigens. Previous reports demonstrated that β-adrenergic receptor (β-AR) signaling promotes immune tolerance by modulation of NK and Treg, mainly through the activation of β2-ARs, but recently we have demonstrated that also β3-ARs induce an immune-tolerant phenotype in mice bearing melanoma. In this report, we demonstrate that β3-ARs support host immune tolerance in the maternal microenvironment by modulating the same immune cells populations as recently demonstrated in cancer. Considering that β3-ARs are modulated by oxygen levels, we hypothesize that hypoxia, through the upregulation of β3-AR, promotes the biological shift toward a tolerant immunophenotype and that this is the same trick that embryo and cancer use to create an aura of immune-tolerance in a competent immune environment. This study confirms the analogies between fetal development and tumor progression and suggests that the expression of β3-ARs represents one of the strategies to induce fetal and tumor immune tolerance.

HLA-C promotes proliferation and cell cycle progression in trophoblast cells

Objectives: The development of maternal-fetal immune tolerance and adequate trophoblast function are essential for the establishment and maintenance of pregnancy. Human leukocyte antigen (HLA), the major histocompatibility complex (MHC) antigen specific to humans, plays an important role in placentation and is involved in many pregnancy-associated diseases. HLA-C is the only classical MHC I gene expressed at the maternal-fetal interface. To investigate whether HLA-C plays an independent role in regulating the development of trophoblasts, we explored the effect of HLA-C expression on placental development.Methods: The role of HLA-C in the growth and migration of trophoblast JAR and HTR-8/Svneo cell lines was investigated after HLA-C-expressing lentivirus transfection.Results: The MTT assay and colony formation assay showed that HLA-C promoted cell proliferation. Furthermore, cell cycle analysis showed that HLA-C overexpression accelerated the transition of trophoblast cells from the G0/G1 phase to the S phase. However, FACS analysis and migration assay indicated that HLA-C had no significant influence on trophoblast apoptosis and migration.Conclusion: Our study demonstrated for the first time that besides being involved in immune tolerance, HLA-C can directly promote placental growth without interacting with immune cells, which could provide a new insight into studying the functions of HLA-C at the maternal-fetal interface.

NLRP3 inflammasome as the potential target mechanism and therapy in recurrent spontaneous abortions

Recurrent spontaneous abortions (RSA) are defined as aborting three or more times within 20 gestational weeks with the same sexual partner. The occurrence of RSA exhibits an upward trend in modern society. The NACHT, LRR and PYD domains‑containing protein 3 (NLRP3) inflammasome, which is an important component of innate immunity, serves a role in the immune response and in disease occurrence. In the present study, it was demonstrated that the disordered regulation of the NLRP3 inflammasome may induce the occurrence of RSA. The results of the present study demonstrated that caspase‑1 activity, interleukin (IL)‑1β and IL‑18 were upregulated in patients with RSA compared with healthy controls. Further investigation was performed to elucidate the mechanism of activation of the NLRP3 inflammasome in patients with RSA. The inhibition of the NLRP3 inflammasome in a RSA mouse model was able to decrease the rate of abortions. Finally, the present study demonstrated that the activated NLRP3 inflammasome was involved in the pathogenesis of RSA through regulation of the Th17 and regulatory T cell imbalance. The present study provides a potential future therapeutic target for RSA via the NLRP3 inflammasome.

Immune checkpoint molecule PD-1 acts as a novel biomarker for the pathological process of gestational diabetes mellitus

AIM

Accumulating evidence suggested that challenge of the maternal-fetal interaction during pregnancy might cause the impairment of immunological hemostasis and lead to gestational diabetes mellitus (GDM) pathological process. Immune checkpoint molecule PD-1 is one of the critical molecule balancing immune response and immunological tolerance.

METHODS

PD-1 expressions on T-cell subsets of GDM patients and control groups were measured via flow cytometric analysis and followed up.

RESULTS

Downregulation of PD-1 acted as an indicator for GDM occurrence in the third trimester of pregnancy. With the recovery of GDM, PD-1 expression restored to normal level.

CONCLUSION

PD-1 expression on T-cell subsets is a novel biomarker for the occurrence and recovery of GDM.

Developing Cures: Targeting Ontogenesis in Cancer

Cancer has long been known to histologically resemble developing embryonic tissue. Since this early observation, a mounting body of evidence suggests that cancer mimics or co-opts developmental processes to facilitate tumor initiation and progression. Programs important in both normal ontogenesis and cancer progression broadly fall into three domains: the lineage commitment of pluripotent stem cells, the appropriation of primordial mechanisms of cell motility and invasion, and the influence of multiple aspects of the microenvironment on the parenchyma. In this review we discuss how derangements in these developmental pathways drive cancer progression with a particular focus on how they have emerged as targets of novel treatment strategies.

Cytokine gene expression at the maternal–fetal interface after somatic cell nuclear transfer pregnancies in small ruminants

The present retrospective study investigated pregnancy rates, the incidence of pregnancy loss and large offspring syndrome (LOS) and immune-related gene expression of sheep and goat somatic cell nuclear transfer (SCNT) pregnancies. We hypothesised that significantly higher pregnancy losses observed in sheep compared with goat SCNT pregnancies are due to the increased amounts of T-helper 1 cytokines and proinflammatory mediators at the maternal–fetal interface. Sheep and goat SCNT pregnancies were generated using the same procedure. Control pregnancies were established by natural breeding. Although SCNT pregnancy rates at 45 days were similar in both species, pregnancy losses between 45 and 60 days of gestation and the incidence of LOS were significantly greater in sheep than in goats. At term, the expression of proinflammatory genes in sheep SCNT placentas was increased, whereas that in goats was similar to that in control animals. Genes with altered expression in sheep SCNT placentas included cytotoxic T-lymphocyte-associated protein 4 (CTLA4), interleukin 2 receptor alpha (IL2RA), cluster of differentiation 28 (CD28), interferon gamma (IFNG), interleukin 6 (IL6), interleukin 10 (IL10), transforming growth factor beta 1 (TGFB1), tumor necrosis factor alpha (TNF-α), interleukin 1 alpha (IL1A) and chemokine (C-X-C motif) ligand 8 (CXCL8). Major histocompatibility complex-I protein expression was greater in sheep and goat SCNT placentas at term than in control pregnancies. An unfavourable immune environment is present at the maternal–fetal interface in sheep SCNT pregnancies.

Immunoregulatory molecules in patients with gestational diabetes mellitus

Induction of maternal-fetal immune tolerance is essential for the development of normal pregnancy. Impaired expression of costimulatory molecules may lead to intense inflammatory reaction, a mechanism involved in the pathophysiology of gestational diabetes mellitus (GDM). The aim of this study was to investigate whether immunoregulatory molecules are involved in the physiopathology of GDM. This case-control study included 30 healthy pregnant women and 20 GDM patients. Flow cytometry was used to assess peripheral blood T subpopulations (CD4(+) and CD8(+)), the expression of immunoregulatory molecules (CD28, ICOS, CTLA-4, and PD-1) and activation markers (CD69 and HLA-DR). Compared to healthy women, GDM patients had a significantly higher frequency of CD4(+)CD69(+) and CD8(+)CD69(+) T cells; only patients with insulin-treated GDM had increased numbers of CD4(+)HLA-DR(+) T cells. We also observed significantly higher percentages of CD4(+)CD28(+)HLA-DR(+), CD3(+)CD4(+)ICOS(+), CD3(+)CD4(+)PD-1(+), CD8(+)CD28(+)CD69(+), CD8(+)CD28(+)HLA-DR(+), CD8(+)CTLA-4(+)HLA-DR(+), and CD3(+)CD8(+)ICOS(+) T cells and lower frequency of CD3(+)CD4(+)CTLA-4(+), CD3(+)CD8(+)CTLA-4(+), and CD8(+)ICOS(+)HLA-DR(+) T cells in GDM patients compared to healthy pregnant women. This first study assessing costimulatory molecules in GDM patients shows that these patients have exacerbated markers of T cell activation along with CTLA-4 deficiency, findings that indicate that the maternal-fetal tolerance is compromised in these patients.

Maternal floor infarction/massive perivillous fibrin deposition: a manifestation of maternal antifetal rejection?

OBJECTIVE

Massive perivillous fibrin deposition (MPFD) and maternal floor infarction (MFI) are related placental lesions often associated with fetal death and fetal growth restriction. A tendency to recur in subsequent pregnancies has been reported. This study was conducted to determine whether this complication of pregnancy could reflect maternal antifetal rejection.

METHODS

Pregnancies with MPFD were identified (n = 10). Controls consisted of women with uncomplicated pregnancies who delivered at term without MPFD (n = 175). Second-trimester maternal plasma was analyzed for panel-reactive anti-HLA class I and class II antibodies. The prevalence of chronic chorioamnionitis, villitis of unknown etiology, and plasma cell deciduitis was compared between cases and controls. Immunohistochemistry was performed on available umbilical vein segments from cases with MPFD (n = 4) to determine whether there was evidence of complement activation (C4d deposition). Specific maternal HLA-antibody and fetal HLA-antigen status were also determined in paired specimens (n = 6). Plasma CXCL-10 concentrations were measured in longitudinal samples of cases (n = 28 specimens) and controls (n = 749 specimens) by ELISA. Linear mixed-effects models were used to test for differences in plasma CXCL-10 concentration.

RESULTS

(i) The prevalence of plasma cell deciduitis in the placenta was significantly higher in cases with MPFD than in those with uncomplicated term deliveries (40% versus 8.6%, P = 0.01), (ii) patients with MPFD had a significantly higher frequency of maternal anti-HLA class I positivity during the second trimester than those with uncomplicated term deliveries (80% versus 36%, P = 0.01); (iii) strongly positive C4d deposition was observed on umbilical vein endothelium in cases of MPFD, (iv) a specific maternal antibody against fetal HLA antigen class I or II was identified in all cases of MPFD; and 5) the mean maternal plasma concentration of CXCL-10 was higher in patients with evidence of MPFD than in those without evidence of MFPD (P < 0.001).

CONCLUSION

A subset of patients with MPFD has evidence of maternal antifetal rejection.

B7h (ICOS-L) maintains tolerance at the fetomaternal interface

In a successful pregnancy, the semiallogeneic fetus is not rejected by the maternal immune system, which implies tolerance mechanisms protecting fetal tissues from maternal immune attack. Here we report that the ICOS-B7h costimulatory pathway plays a critical role in maintaining the equilibrium at the fetomaternal interface. Blockade of this pathway increased fetal resorption and decreased fetal survival in an allogeneic pregnancy model (CBA female × B6 male). Locally in the placenta, levels of regulatory markers such as IDO and TGF-β1 were reduced after anti-B7h monoclonal antibody treatment, whereas levels of effector cytokines (eg, IFN-γ) were significantly increased. In secondary lymphoid organs, enhanced IFN-γ and granzyme B production (predominantly by CD8(+) T cells) was observed in the anti-B7h-treated group. The deleterious effect of B7h blockade in pregnancy was maintained only in CD4 knockout mice, not in CD8 knockout mice, which suggests a role for CD8(+) T cells in immune regulation by the ICOS-B7h pathway. In accord, regulatory CD8(+) T cells (in particular, CD8(+)CD103(+) cells) were significantly decreased after anti-B7h monoclonal antibody treatment, and adoptive transfer of this subset abrogated the deleterious effect of B7h blockade in fetomaternal tolerance. Taken together, these data support the hypothesis that B7h blockade abrogates tolerance at the fetomaternal interface by enhancing CD8(+) effector response and reducing local immunomodulation mediated by CD8(+) regulatory T cells.

Evidence for a role for the adaptive immune response in human term parturition

PROBLEM

Spontaneous labor at term involves leukocyte recruitment and infiltration into the choriodecidua; yet, characterization of these leukocytes and their immunological mediators is incomplete. The purpose of this study was to characterize the immunophenotype of choriodecidual leukocytes as well as the expression of inflammatory mediators in human spontaneous parturition at term.

METHOD OF STUDY

Choriodecidual leukocytes were analyzed by FACS, immunohistochemistry, and RT-PCR in three different groups: (i) preterm gestation delivered for medical indications without labor; (ii) term pregnancy without labor; and (iii) term pregnancy after spontaneous labor.

RESULTS

Two T-cell subsets of memory-like T cells (CD3(+) CD4(+) CD45RO(+) and CD3(+) CD4(-) CD8(-) CD45RO(+) cells) were identified in the choriodecidua of women who had spontaneous labor. Evidence for an extensive immune signaling network composed of chemokines (CXCL8 and CXCL10), chemokine receptors (CXCR1-3), cytokines (IL-1β and TNF-α), cell adhesion molecules, and MMP-9 was identified in these cells during spontaneous labor at term.

CONCLUSIONS

The influx of memory-like T cells in the choriodecidua and the evidence that they are active by producing chemokines and cytokines, and expressing chemokine receptors, cell adhesion molecules, and a matrix-degrading enzyme provides support for the participation of the adaptive immune system in the mechanisms of spontaneous parturition at term.

Maternal HLA panel-reactive antibodies in early gestation positively correlate with chronic chorioamnionitis: evidence in support of the chronic nature of maternal anti-fetal rejection

PROBLEM

Maternal tolerance of the fetus is essential for viviparity, yet anti-fetal rejection occurs in several pregnancy complications. Chronic chorioamnionitis is a feature of anti-fetal cellular rejection. There is a robust association between chronic chorioamnionitis and maternal seropositivity for anti-human leukocyte antigen (HLA) panel-reactive antibodies (PRA) at the time of delivery. This longitudinal study was performed to assess maternal HLA PRA status in early gestation and the temporal evolution of maternal HLA PRA in the context of chronic chorioamnionitis and, thereby, to determine whether HLA PRA during the course of pregnancy is useful for the detection of anti-fetal rejection.

METHOD OF STUDY

Maternal sera obtained before 16 weeks of gestation and at delivery were analyzed for HLA PRA in cases with (N = 100) and without (N = 150) chronic chorioamnionitis.

RESULTS

IgG (but not IgM) HLA class I and II PRA positivity at delivery was higher in cases with chronic chorioamnionitis than in those without chronic chorioamnionitis. IgG HLA class I PRA positivity before 16 weeks of gestation was higher in cases with chronic chorioamnionitis than in those without (30.3 versus 13.3%; P = 0.001). Positive conversion (negative HLA PRA before 16 weeks of gestation but positive at delivery) of IgG HLA class I and II PRA was significantly associated with chronic chorioamnionitis. Fetal HLA class I antigen-specific antibodies were confirmed in 12 of 16 mothers tested who were sensitized to HLA class I antigens before 16 weeks of gestation.

CONCLUSION

Positive maternal HLA PRA before 16 weeks of gestation and the temporal evolution of maternal HLA PRA are associated with the presence of chronic chorioamnionitis at the time of delivery. Maternal IgG HLA PRA has the potential to be a monitoring tool of anti-fetal rejection. Furthermore, the findings herein indicate that subsets of fetuses are exposed to alloimmune HLA antibodies for months, especially in cases with chronic chorioamnionitis.

Postpartum group a Streptococcus sepsis and maternal immunology

Group A Streptococcus (GAS) is an historically important agent of puerperal infections and sepsis. The inception of hand-washing and improved hospital hygiene drastically reduced the incidence of puerperal sepsis, but recently the incidence and severity of postpartum GAS infections has been rising for uncertain reasons. Several epidemiological, host, and microbial factors contribute to the risk for GAS infection and mortality in postpartum women. These include the mode of delivery (vaginal versus cesarean section), the location where labor and delivery occurred, exposure to GAS carriers, the altered immune status associated with pregnancy, the genetic background of the host, the virulence of the infecting GAS strain, and highly specialized immune responses associated with female reproductive tract tissues and organs. This review will discuss the complicated factors that contribute to the increased susceptibility to GAS after delivery and potential reasons for the recent increase observed in morbidity and mortality.