Decrease in the proportion of granulated CD56+ T-cells in patients with a history of recurrent abortion

Immune Checkpoints in Recurrent Pregnancy Loss: New Insights into a Detrimental and Elusive Disorder

Recurrent pregnancy loss (RPL) refers to two or more miscarriages before 20 weeks gestation. Its prevalence is 1-2%; its pathogenesis remains unexplained in more than 50% of cases, in which the cause is thought to be abnormal immune activity during placentation leading to a lack of pregnancy-induced immune tolerance. It is unknown whether immune activity is deranged in the endometrium of women with RPL. We studied the gene expression and the quantitative tissue protein levels of three immune checkpoints (CD276, which enhances cytotoxic T-cell activity, cytotoxic T-lymphocyte-associated antigen-4 [CTL-4], which reduces Th1 cytokine production, and lymphocyte activation gene-3 [LAG-3], which shows suppressive activity on Tregs and CD4+ T-cells) in endometrial samples from 27 women with unexplained RPL and in 29 women with dysfunctional uterine bleeding and previous uneventful pregnancies as controls. RNA isolation, real-time PCR, protein isolation, and ELISA were performed. CD276 gene expression and protein tissue levels were significantly lower in the endometrium of the RPL group than in the controls, whereas both CTL-4 and LAG-3 were significantly higher. This difference suggests defective endometrial immune regulation and overactivation of immune response in women with a history of RPL, at least in relation to controls with dysfunctional uterine bleeding and previous normal reproductive history.

Understanding human immunity in idiopathic recurrent pregnancy loss

Miscarriage, defined as the loss of a pregnancy before a viable gestation, affects 1 in 6 couples. Recurrent pregnancy loss (RPL), defined as two or more miscarriages, affects up to 1.9% of couples. The physical, psychological, and financial impact of miscarriage can be substantial. However, despite its multifactorial etiology, for up to 50% of couples a reason behind this condition cannot be identified, termed 'idiopathic RPL'. Much recent research has strived to understand this, with immune dysregulation being a source of particular interest. In this short review we summarize the current evidence on the complex role of the immune system both pre- and early post-conception in RPL. A key question is whether systemic peripheral blood markers, in particular natural killer cell and T cells, may be utilized to accurately predict and/ or diagnose those pregnancies at high risk of loss. Given the invasive nature of endometrial testing, identification of reliable peripheral immune biomarkers is particularly appealing. Clinical trials using potent immunomodulatory agents, including intravenous immunoglobulin, donor leukocyte immunization, and tumor necrosis factor (TNF)-α inhibitors, have been undertaken with the primary objective of preventing miscarriage in women with RPL. Standardisation of both diagnostic and prognostic immune cell testing assays is required to permit accurate identification of those women who may benefit from immunomodulation. Prompt clarification is required to meet the increasing expectation from couples and clinicians, as without these advancements women are at risk of exposure to potent immune-therapies and subsequent studies are at risk of failure, generating further controversy regarding the role of immune dysregulation in women with RPL. Through this review we highlight clear gaps in our current knowledge on immune activity in RPL.

The Role of Type I and Type II NKT Cells in Materno-Fetal Immunity

NKT cells represent a small but significant immune cell population as being a part of and bridging innate and adaptive immunity. Their ability to exert strong immune responses via cytotoxicity and cytokine secretion makes them significant immune effectors. Since pregnancy requires unconventional maternal immunity with a tolerogenic phenotype, investigation of the possible role of NKT cells in materno-fetal immune tolerance mechanisms is of particular importance. This review aims to summarize and organize the findings of previous studies in this field. Data and information about NKT cells from mice and humans will be presented, focusing on NKT cells characteristics during normal pregnancy in the periphery and at the materno-fetal interface and their possible involvement in female reproductive failure and pregnancy complications with an immunological background.

Elevated percentage of CD3+T cells and pregnancy outcome in women with recurrent pregnancy loss

BACKGROUND

Even though the immune factor is not yet established as a cause of recurrent pregnancy loss (RPL), tons of other studies have shown that a significant proportion of immune abnormalities exist in RPL.

METHODS

We conducted a retrospective cohort study with 850 women who were diagnosed with RPL. The percentages of CD3⁺, CD3⁺CD4⁺ and CD3⁺CD8⁺T cells of each participant, detected by flow cytometry, were obtained before pregnancy and at 6 weeks of gestation as part of their routine medical examination.

RESULTS

Peripheral blood CD3⁺ T cells prior to pregnancy (at baseline), increased significantly in women who had a miscarriage compared with the subsequent live birth group. Moreover, the percentage of CD3⁺ and CD3⁺CD4⁺T cells during pregnancy increased significantly as compared with the baseline level. After adjusting for potential confounders, the multiple regression equation showed that the CD3⁺ T cells <67.84% was associated with the risk of miscarriage (OR 1.05, 95% CI, 1.01 to 1.11, p = .04). Additionally, a nonlinear relationship was observed between the percentage of CD3⁺T cells and the risk of miscarriage.

CONCLUSIONS

The risk of miscarriage increased as the percentage of population with CD3+ value below 67.84% has increased, nevertheless, the miscarriage risk did not increase further when the level of CD3⁺T cells was >67.84%.

Diminished Frequency of Menstrual and Peripheral Blood NKT-Like Cells in Patients With Unexplained Recurrent Spontaneous Abortion and Infertile Women

Systemic monitoring of immune system may not precisely outline the local immune status in the uterus. This survey is a continuation of our previous studies on potential usefulness of menstrual blood (MB) immunophenotyping as a tool for investigation of immunological disturbances in pregnancy-related disorders. Peripheral blood (PB) and MB from healthy fertile (n = 15), unexplained recurrent spontaneous abortion (URSA; n = 15), and unexplained infertile women (n = 8) were collected simultaneously in the second day of their menstrual cycle and frequency of natural killer T (NKT)-like cell subpopulations were assessed by flow cytometry. Menstrual blood of all experimental groups contained higher percentage of TCRαβ⁺, CD45RO⁺, and CD16^- NKT-like cells compared to corresponding PB. Frequency of MB NKT-like cells in unexplained infertile participants was lower than fertile and URSA groups. Compared to normal participants, patients with URSA had lower frequency of PB TCRαβ⁺ and higher CD16⁺, while in infertile woman frequencies of PB CD45RO⁺, CD45RO^-, CD16^-, IL17⁺, and MB CD45RO⁺ NKT-like cells were lower. Although, PB and MB seemingly have the same histological nature, our results showed that MB contained different composition of NKT-like subsets with different cytokine profiles and could be viewed as one potential biological sample for evaluation of patients with infertility and URSA.

CD56+ T cells are increased in kidney transplant patients following cytomegalovirus infection

BACKGROUND

CD56+ T cells previously have been identified as potentially cytotoxic lymphocytes, and relative numbers are increased in some infectious diseases.

PATIENTS AND METHODS

Relative proportions of CD56+ T cells were measured by flow cytometry in groups of renal transplant patients differing in cytomegalovirus (CMV) status of donor (D) and recipient (R). These measurements were related to episodes of CMV viremia.

RESULTS

Patient groups in which recipients (R+) or donors (D+/R-) were CMV+ had significantly higher proportions of CD56+ T cells (5.11 ± 0.69% and 5.42 ± 1.01%, respectively) than the D-/R- group (1.9 ± 0.35%; P = 0.0018 and 0.017, respectively). In the high-risk D+/R- group, it was found that patients who had post-transplant CMV viremia had higher levels than those who remained CMV negative (9.09 ± 2.34% vs. 3.16 ± 1.22%; P = 0.01). CD56+ T cells from R+ and D+/R- groups had higher proportions of both CD4+ and CD8+ cells than the D-/R- group. When activation markers were examined, some CD56+ T cells from both CMV+ groups had a TEM phenotype, with significantly more expressing CD45RO and NKG2C, and less expressing CD28, CD62L, CD127, and CD161 compared to the D-/R- group. Some CD56+ T cells showed specificity for CMV antigens and similar proportions of CD8+ cells were positive for class I HLA-CMV tetramers containing immunodominant CMV peptides compared to the majority CD56- T cells.

CONCLUSION

The results show significant increases in proportions of CD56+ T cells in relation to CMV infection in renal transplant patients and suggest that these cells have a cytotoxic function against CMV-infected cells.

Regulatory T cells, inflammation, and endoplasmic reticulum stress in women with defective endometrial receptivity

OBJECTIVE

To investigate immunologic parameters and endoplasmic reticulum (ER) stress associated with unexplained infertility.

DESIGN

Case-control study.

SETTING

Academic center.

PATIENT(S)

Women with no fertility problems (FS) (n = 13), women with recurrent miscarriage (RM) (n = 15) and women with repeated in vitro fertilization failure (RIF) (n = 15).

INTERVENTION(S)

Endometrial biopsy and collection of peripheral blood during the midsecretory phase of menstrual cycle.

MAIN OUTCOME MEASURE(S)

Leptin, resistin, soluble tumor necrosis factor receptor (sTNF-R), myeloperoxidase (MPO), soluble intercellular adhesion molecule 1 (sICAM-1), and interleukin 22 (IL-22) concentration in peripheral blood, endometrial CD3(+), CD4(+), CD5(+), CD8(+), and FoxP3(+) T lymphocytes, and endometrial expression of HSPA5, a specific marker of ER stress.

RESULT(S)

We found an increase of proinflammatory molecules such as resistin, leptin, and IL-22 in both RM and RIF patients; sTNF-R and MPO only in RIF patients when compared with the FS women. We also found in endometria of infertile women a statistically significant increase of CD3(+), CD4(+), CD8(+) in both RM and RIF patients and CD5(+) in RM patients when compared with FS women. This was paralleled by a statistically significant reduction of infiltrating FoxP3(+) regulatory T cells. Finally, endometrial HSPA5 expression levels were statistically significantly up-regulated in both RM and RIF patients.

CONCLUSION(S)

Women with RM and RIF showed an increase of circulating proinflammatory cytokines, altered endometrial T lymphocytes subsets, and signs of endometrial ER stress.

Increase of peripheral blood TCD8+ cells in women with recurrent miscarriage

Recurrent miscarriage (RM) is one of the most prevalent reproductive problems faced by couples that may affect as many as 2% of women in reproductive age. The causes of its abnormality have attracted the attention of many researchers. We aim to determine the different T-cell subsets in women with RM and normal control. In this prospective case-control study, peripheral blood was taken from women with RM (n = 25) and normal women (n = 17), during the mid-luteal phase. The percentage of CD3, CD3(+)CD4(+), CD3(+)CD8(+) markers and also CD4/CD8 ratio was detected in the patients and control group by flow cytometry. The proportion of TCD8(+) was significantly higher in RM women compared with the control group (p < 0.05). However, there was no statistical difference in percentage of total TCD3(+) and TCD4(+) cells between the RM and control women. Also, the CD4/CD8 ratio was lower in the RM women compared with the control women. These observations support the concept that increase of TCD8(+) lymphocytes could be involved in the aetiology of RM.

Postpartum increase of serum thioredoxin concentrations and the relation to CD8 lymphocytes

BACKGROUND

There are few data on oxidative stresses during and after pregnancy, although aggravation of autoimmune disease is implicated in oxidative stress and occurs frequently in the postpartum period. Thioredoxin (TRX) is a stress-inducible protein, and is used as a good biomarker for oxidative stress. To clarify the changes in the levels of oxidative stress during and after pregnancy, we examined serum TRX levels and the numbers of lymphocyte subsets.

METHODS

We measured serum TRX levels by enzyme-linked immunosorbent assay (ELISA), and neutrophils, lymphocytes, and CD4 and CD8 lymphocytes by flow cytometry in peripheral blood from 88 healthy pregnant women, 26 just after delivery women, 77 healthy postpartum women and 19 healthy non-pregnant women.

RESULTS

The serum levels of TRX did not change during pregnancy, but increased in four, seven and 10 months postpartum. Serum TRX levels were correlated with the percentages of neutrophils in normal non-pregnant women and women one month postpartum, and with those of CD8 lymphocytes in early pregnant women and women one and four months postpartum.

CONCLUSIONS

Oxidative stress increased in the postpartum period, and the levels at one and four months postpartum were related to CD8 lymphocytes.

Expression of CD28 and cytotoxic T lymphocyte antigen 4 at the maternal-fetal interface in women with unexplained pregnancy loss

OBJECTIVE

To investigate the expression of CD28 and CTLA-4, two costimulatory molecules involved in T-cell activation at the maternal-fetal interface in women with unexplained pregnancy loss.

METHODS

A total of 57 women, 39 with unexplained spontaneous abortion (SA) and 18 with unexplained recurrent spontaneous abortion (RSA), were enrolled in the study. A high-resolution spectratyping analysis of fluorescent bands was performed to detect CD28 and CTLA-4 expression in decidual tissues.

RESULTS

The mean expression of CTLA-4 mRNA was significantly higher in women with SA than in controls (P<0.05). Moreover, the expression of CTLA-4 was higher in SA patients with genotype AA and phenotype A+ (AA+AG) than in controls (P<0.01). The expression of CTLA-4 was not significantly different in patients with RSA and in controls. The expression of CD28 was significantly decreased in patients with RSA (P<0.01) and SA (P<0.05) compared with controls. The mean ratios of CTLA-4/CD28 were significantly higher in patients with RSA (P<0.01) and SA (P<0.05) than in controls.

CONCLUSIONS

This study suggests that an imbalance in CTLA-4/CD28 expression or suppressed T-cell activity at the maternal-fetal interface may confer susceptibility to unexplained pregnancy loss.

Proportion of CD56+3+ T cells in decidual and peripheral lymphocytes of normal pregnancy and spontaneous abortion with and without history of recurrent abortion

PROBLEM

The present study investigated the proportion of CD56+3+ T cells in maternal peripheral and decidual lymphocytes in normal pregnancy and spontaneous abortion with and without history of recurrent spontaneous abortion (RSA).

METHOD OF STUDY

Maternal peripheral blood and decidua were taken from normal pregnancies and missed abortions with and without RSA. Decidual lymphocytes were prepared from decidual tissue and analyzed by flow cytometry.

RESULTS

In normal pregnancy, the percentages of CD56+3+ T cells in decidual lymphocytes did not differ from those in the peripheral blood. However, the proportion of CD56+3+ T cells in decidual CD3+ T cells increased higher than that in the peripheral CD3+ T cells. The percentages of decidual CD56+3+ T cells in missed abortions with and without RSA were lower than those in normal pregnancies.

CONCLUSION

CD56+3+ T cells may play a role in the maintenance of pregnancy. The phenomenon, where the proportion of CD56+3+ T cells in decidual lymphocytes decreases, may be due to an immunologic event leading to missed abortion.