1. Guerin LR, Prins JR, Robertson SA. Regulatory T-cells and immune tolerance in pregnancy: a new target for infertility treatment? Hum Reprod Update. 2009 Sep-Oct;15(5):517-35. Epub 2009 Mar 11. BACKGROUND: Adaptation of the maternal immune response to accommodate the semi-allogeneic fetus is necessary for pregnancy success, and disturbances in maternal tolerance are implicated in infertility and reproductive pathologies. T regulatory (Treg) cells are a recently discovered subset of T-lymphocytes with potent suppressive activity and pivotal roles in curtailing destructive immune responses and preventing autoimmune disease. METHODS: A systematic review was undertaken of the published literature on Treg cells in the ovary, testes, uterus and gestational tissues in pregnancy, and their link with infertility, miscarriage and pathologies of pregnancy. An overview of current knowledge on the generation, activation and modes of action of Treg cells in controlling immune responses is provided, and strategies for manipulating regulatory T-cells for potential applications in reproductive medicine are discussed. RESULTS: Studies in mouse models show that Treg cells are essential for maternal tolerance of the conceptus, and that expansion of the Treg cell pool through antigen-specific and antigen non-specific pathways allows their suppressive actions to be exerted in the critical peri-implantation phase of pregnancy. In women, Treg cells accumulate in the decidua and are elevated in maternal blood from early in the first trimester. Inadequate numbers of Treg cells or their functional deficiency are linked with infertility, miscarriage and pre-eclampsia. CONCLUSIONS: The potency and wide-ranging involvement of Treg cells in immune homeostasis and disease pathology indicates the considerable potential of these cells as therapeutic agents, raising the prospect of their utility in novel treatments for reproductive pathologies. Free full text article.
2. Yang H, Qiu L, Di W, Zhao A, Chen G, Hu K, Lin Q. Proportional change of CD4(+)CD25(+) regulatory T cells after lymphocyte therapy in unexplained recurrent spontaneous abortion patients. Fertil Steril. 2008 Aug 1. OBJECTIVE: To investigate the proportional changes of CD4(+)CD25(+) regulatory T cells in peripheral blood after lymphocyte therapy in unexplained recurrent spontaneous abortion (URSA) patients. DESIGN: Prospective cohort study. SETTING: University Hospital. PATIENT(S): Twenty-five URSA patients. INTERVENTION(S): Measurements of CD4(+)CD25(+) regulatory T cells in peripheral blood before and after paternal or third-party lymphocyte immunization. MAIN OUTCOME MEASURE(S): The proportion of CD4(+)CD25(bright) regulatory T cells and the percentage of CD25(bright) cells in the CD4(+) T-cell population. RESULT(S): The proportion of CD4(+)CD25(bright) T cells in peripheral blood from URSA patients was increased significantly after paternal or third-party lymphocyte immunization therapy, whereas the percentage of CD4(+)CD25(dim) cells were decreased significantly. The percentage of CD4(+)CD25(bright) cells in the CD4(+) T-cell population was significantly increased, and the proportion of CD4(+)CD25(bright) T cells was significantly higher in successfully pregnant women than in those with pregnancy loss after lymphocyte therapy. CONCLUSION(S): Allogeneic lymphocyte therapy can enhance the percentage of CD4(+)CD25(bright) regulatory T cells in peripheral blood, therefore CD4(+)CD25(+) regulatory T cells may serve as a novel biomarker for monitoring allogeneic lymphocyte therapy in URSA patients.
3. Mei S, Tan J, Chen H, Chen Y, Zhang J. Changes of CD4(+)CD25(high) regulatory T cells and FOXP3 expression in unexplained recurrent spontaneous abortion patients. Fertil Steril. 2010 Jan 5. OBJECTIVE: To investigate the proportions of CD4(+)CD25(high) T cells and forkhead box p3 (FOXP3) expression in peripheral blood and decidua in patients with unexplained recurrent spontaneous abortion (URSA). DESIGN: Prospective clinical study. SETTING: University hospital. PATIENT(S): 125 URSA patients, 35 normal early pregnant women, and 28 normal nonpregnant women. INTERVENTION(S): Measurements of CD4(+)CD25(high) T cells and FOXP3 expression in peripheral blood and decidua. MAIN OUTCOME MEASURE(S): The proportions of CD4(+)CD25(high) T cells and FOXP3 expression. RESULT(S): In peripheral blood, statistically significantly higher proportions of CD4(+)CD25(high) T cells and FOXP3 expression were observed in normal early pregnant women compared with normal nonpregnant women and URSA patients; a statistically significantly lower proportion of CD4(+)CD25(high) T cells was observed in nonpregnant URSA patients compared with URSA patients who had early miscarriages and normal nonpregnant women. In the decidua, statistically significantly lower proportions of CD4(+)CD25(high) T cells and FOXP3 expression were found in URSA patients with early miscarriages compared with normal early pregnant women. CONCLUSION(S): The CD4(+)CD25(high) T cells may play an important role in maintaining a normal pregnancy. The reduction in CD4(+)CD25(high) T cells may involve in the pathogenesis of URSA, and is correlated with lower FOXP3 expression.
4. Steinborn A, Engst M, Haensch GM, Mahnke K, Schmitt E, Meuer S, Sohn C. Small for gestational age (SGA) neonates show reduced suppressive activity of their regulatory T cells. Clin Immunol. 2010 Feb;134(2):188-197. Epub 2009 Nov 26.
Little information exists concerning the role of fetal regulatory T cells (Tregs) during intrauterine development. We examined whether complications such as reduced birth weight or the occurrence of preterm labor were associated with deficiencies in the number or in the immunosuppressive activity of Tregs in the fetal circulation. Their total number did not change during normal or complicated pregnancy. In contrast, their level of FoxP3 expression decreased continuously with gestational age and was significantly reduced in the presence of spontaneous term, but not preterm labor. In small for gestational age (SGA) neonates, FoxP3 expression was constantly decreased when compared to age matched healthy neonates. In accordance with the low FoxP3 expression, the suppressive activity of the Tregs from spontaneously term delivered and from SGA babies was significantly reduced. We propose that the level of FoxP3 expression in the fetal Tregs may be a potential regulator of their suppressive activity.
5. Toldi G, Svec P, Vasarhelyi B, Meszaros G, Rigo J, Tulassay T, Treszl A.
Decreased number of FoxP3+ regulatory T cells in preeclampsia. Acta Obstet Gynecol Scand. 2008;87(11):1229-1233
Systemic inflammation is characteristic for preeclampsia (PE). A hypothesis for immune dysregulation is that the function of regulatory T cells (CD4(+)FoxP3(+), Tregs) inhibiting the activation of lymphocytes is impaired. We investigated the proportion of Tregs and their cellular network in preeclamptic women. Fifteen preeclamptic and 17 healthy pregnant women were enrolled in the 32nd gestational week (median age 29 (range 22-45) and 32 (range 26-38) years, respectively). PE was diagnosed according to international criteria at a median of 30 gestational weeks (range 21-31). Peripheral blood was taken and blood mononuclear cells were isolated. Flow cytometry was used to determine the proportion of regulatory (CD4+FoxP3+) T cells, lymphoid and myeloid dendritic cells, natural killer and natural killer T cells, naive and memory and activated CD4+ and CD8+cells. The proportion of Tregs and that of naive CD4(+)CD45RA(+) cells was lower in preeclamptic than in control women (p=0.025, p=0.04, respectively). The proportion of other investigated cell types did not differ. Low Treg numbers may support the notion that PE shares similar features to autoimmune disorders. Low Treg numbers are not reflected in the proportion of activated lymphocytes, at least in this stage of pregnancy. This does not exclude, however, the functional alterations of these cell types.
6. Seol HJ, Oh MJ Lim JE, Jung NH, Yoon SY, Kim HJ.The role of CD4+CD25bright regulatory T cells in the maintenance of pregnancy, premature rupture of membranes, and labor. Yonsei Med J. 2008 Jun 30;49(3):366-71.PURPOSE: The aim of this study was to evaluate the changes of the regulatory T cell subset in peripheral blood caused by gestational age and premature rupture of membranes (PROM) with or without labor to verify the role of regulatory T cells in pregnancy. PATIENTS AND METHODS: We investigated regulatory T cell distribution in the peripheral blood of pregnancies during the first trimester (group I, n=2), the second trimester (group II, n=12), and the third trimester without PROM and labor (group III, n=15). In addition, we evaluated pregnancies in the third trimester complicated by PROM (group IV, n=4) and labor with no complication by PROM (Group V, n=5). Comparisons were made with non-pregnant controls (group VI, n=4) using flow cytometry. RESULTS: During uncomplicated pregnancy, the CD4(+)CD25(bright) regulatory T cell population decreased with advancing gestational age (group I=3.35+/-0.47, group II=2.91+/-1.44, group III=2.81+/-1.36, group VI=2.52+/-0.71, p=NS). When we compared group IV with group III and V to evaluate the changes of the regulatory T cells with PROM, the CD4(+)CD25(bright) regulatory T cell population was significantly decreased in group IV compared to group III (p=0.001) and group V (p=0.026). CONCLUSION: The present results revealed that the regulatory T cell population increased in early pregnancy but decreased in pregnancies complicated by PROM, indicating that regulatory T cells might be related to the maintenance of pregnancy.
7. Gershon RK. A disquisition on suppressor T cells. Transplant Rev. 1975;26:170-85.
The main points that I have put forth are that: (1) suppressor T cell activity cannot be explained as simply being too much help; (2) feedback signals from target cells are of crucial importance in determining and maintaining the activity of suppressor T cells; (3) whenever T cells are triggered by antigen, suppression occurs. Immune responses only occur when countermanding signals are also generated. Both intrinsic and extrinsic adjuvanticity is the operational production of countermanding signals; (4) memory T cells are qualitatively different from normal T cells in their sensitivity to feedback signals and also in their susceptibility to suppression; (5) mature thymus dependent B cells cannot be rendered tolerant by the direct action of antigen, while immature and thymus independent B cells can; (6) the mechanism of suppression induced by exogenously administered antigens and that by normal differentiation products (i.e.: GVH; allotypes), is different; (7) generation of suppressor cells requires or results from complex interactions between subpopulations of cells, making it impossible under present conditions to determine which cell is doing what and to which; (8) further work is required before a full understanding of the importance, mechanism of action and other aspects of suppressor T cell function can be fully understood
8. Sakaguchi S, Sakaguchi N, Asano M, Itoh M, Toda M. Immunologic self-tolerance maintained by activated T cells expressing IL-2 receptor alpha-chains (CD25). Breakdown of a single mechanism of self-tolerance causes various autoimmune diseases. J Immunol. 1995 Aug 1;155(3):1151-64. Approximately 10% of peripheral CD4+ cells and less than 1% of CD8+ cells in normal unimmunized adult mice express the IL-2 receptor alpha-chain (CD25) molecules. When CD4+ cell suspensions prepared from BALB/c nu/+ mice lymph nodes and spleens were depleted of CD25+ cells by specific mAb and C, and then inoculated into BALB/c athymic nude (nu/nu) mice, all recipients spontaneously developed histologically and serologically evident autoimmune diseases (such as thyroiditis, gastritis, insulitis, sialoadenitis, adrenalitis, oophoritis, glomerulonephritis, and polyarthritis); some mice also developed graft-vs-host-like wasting disease. Reconstitution of CD4+CD25+ cells within a limited period after transfer of CD4+CD25- cells prevented these autoimmune developments in a dose-dependent fashion, whereas the reconstitution several days later, or inoculation of an equivalent dose of CD8+ cells, was far less efficient for the prevention. When nu/nu mice were transplanted with allogeneic skins or immunized with xenogeneic proteins at the time of CD25- cell inoculation, they showed significantly heightened immune responses to the skins or proteins, and reconstitution of CD4+CD25+ cells normalized the responses. Taken together, these results indicate that CD4+CD25+ cells contribute to maintaining self-tolerance by down-regulating immune response to self and non-self Ags in an Ag-nonspecific manner, presumably at the T cell activation stage; elimination/reduction of CD4+CD25+ cells relieves this general suppression, thereby not only enhancing immune responses to non-self Ags, but also eliciting autoimmune responses to certain self-Ags. Abnormality of this T cell-mediated mechanism of peripheral tolerance can be a possible cause of various autoimmune diseases.
9. Xia XY, Zhou X, Huang YF. [Transcription factor FOXP3 and reproduction]
[Article in Chinese] Zhong Nan Ke Xue. 2009 Jul;15(7):642-5.
Adaptation of the maternal immune response to accommodate the semi-allogeneic fetus is necessary for pregnancy success, and disturbances in maternal tolerance are implicated in miscarriage. FOXP3, a member of the X chromosome-encoded forkhead transcription factor family, is indispensable for the differentiation of regulatory T cells. Regulatory T cells (CD4+ CD25+ FOXP3+ Treg) are pivotal to the maintenance of self-tolerance and the control of immune homeostasis. Many studies show that CD4+ CD25+ FOXP3+ Treg cells are essential for maternal tolerance of the conceptus. Treg cells accumulate in the decidua and are elevated in maternal blood from early in the first trimester. Inadequate expression of FOXP3 is associated with recurrent spontaneous abortion, unexplained infertility and recurrent implantation failure. CD4+ CD25+ FOXP3+ Treg cells offer an attractive target for treatment of auto-immune disease and allograft tolerance and might become a powerful new tool for the treatment of fertility pathologies stemming from disturbances in immune tolerance. This paper reviews the structure, function, expression regulation of FOXP3 and its relation with reproduction.
10. Jin LP, Chen QY, Zhang T, Guo PF, Li DJ. The CD4+CD25 bright regulatory T cells and CTLA-4 expression in peripheral and decidual lymphocytes are down-regulated in human miscarriage. Clin Immunol. 2009 Dec;133(3):402-10. Epub 2009 Sep 18.
The present study was undertaken to analyze the changes in the proportion of CD4(+)CD25(bright) regulatory T (Treg) cells and the expression of costimulatory molecules, CTLA-4 and CD28, in the peripheral blood and deciduas in the setting of non-pregnancy, normal early pregnancy and miscarriage. In this study, we showed that CD4(+)CD25(bright) T cells significantly increased in the peripheral of normal pregnancy compared to that of non-pregnancy. The proportions of CD4(+)CD25(bright) T cells in both peripheral blood and deciduas were significantly lower in miscarriage than that of normal pregnancy. CD4(+)CD25(bright) T cells were characterized by high-level FoxP3 expression and low-level CD69 expression. An increase in the CD28 mRNA expression was accompanied by a decrease in the CTLA-4 mRNA expression in decidual tissues from human miscarriage. The ratios of CTLA-4(+)/CD28(+) in miscarriage were significantly lower than that of the normal pregnancy both in the peripheral and in deciduas. The ratio of CTLA-4(+)/CD28(+) in CD4(+)CD25(bright) T cells was significantly higher than that of the CD4(+)CD25(dim) T cells both in normal pregnancy and in miscarriage. The decidual T cells in the miscarriage appeared higher in responsiveness and IL-2 and IFN-gamma production in comparison with the decidual T cells in the early pregnancy. These results above suggest that CD4(+)CD25(bright) Treg cells might play a role in the maintenance of pregnancy via up-regulation of CTLA-4 expression. The down-regulation of Treg cells and their functions, and the imbalance of positive and negative regulators of costimulatory signals might lead to an abnormal immune milieu, which confer susceptibility to pregnancy loss.
11. Jasper MJ, Tremellen KP, Robertson SA. Primary unexplained infertility is associated with reduced expression of the T-regulatory cell transcription factor Foxp3 in endometrial tissue. Mol Hum Reprod. 2006 May;12(5):301-8. Epub 2006 Mar 30.
A receptive endometrial environment requires adequate immunological tolerance to protect the implanting embryo from maternal immune rejection. Studies in mice implicate CD4+CD25+ T-regulatory (Treg) cells as essential mediators of immune tolerance in pregnancy. The aim of this study was to evaluate the link between Treg cells and fertility in women. Expression of Foxp3, a master regulator of Treg cell differentiation, was quantified in endometrial tissue from women experiencing primary unexplained infertility and normal fertile women. Endometrial biopsies were collected during the mid-secretory phase of the menstrual cycle from women meeting rigorously defined criteria for unexplained infertility after experiencing repeated failed cycles of IVF treatment (infertile, n = 10), or women classified as proven fertile (control, n = 12). Expression of Foxp3 mRNA was reduced approximately two-fold in the tissue of infertile women. In contrast, mRNAs encoding T cell transcription factors T-bet and GATA3, associated with differentiation of Th1 and Th2 CD4+ T cells respectively, were unchanged. Treg cell differentiation is controlled by TGFbeta, but the relative abundance in endometrial tissue of TGFbeta1, TGFbeta2, TGFbeta3 mRNAs was not changed in infertile women. Cytokines influencing Th1 and Th2 cell differentiation, including IFNgamma, IL-2, IL-4, IL-5, IL-10 and IL-12p40, as well as dendritic cell-regulating cytokines IL-1alpha, IL-1beta, IL-6, LIF, GM-CSF and TNFalpha were also expressed similarly regardless of fertility status. The finding of reduced endometrial Foxp3 implicates impaired differentiation of uterine T cells into the Treg phenotype as a key determinant of fertility in women. The factors underpinning this aberration in the immune response remain to be identified.
12. Kessel A, Ammuri H, Peri R, Pavlotzky ER, Blank M, Shoenfeld Y, Toubi E. Intravenous immunoglobulin therapy affects T regulatory cells by increasing their suppressive function. J Immunol. 2007 Oct 15;179(8):5571-5. Intravenous Ig therapy (IVIg) is reported to be a useful regimen in treating autoimmune diseases. In this study, we asked whether IVIg (in vitro) could increase the expression of TGF-beta, IL-10, and the transcription factor FoxP3 in T regulatory (Treg) cells, and the idea that IVIg could enhance suppressive properties of these cells. CD4(+) T cells from 12 healthy individuals were cultured in the presence or absence of IVIg vs human control IgG during 16, 24, and 36 h. Using FACS analysis and gating on CD4(+)CD25(high) Treg cells, we assessed the expression of intracellular TGF-beta, IL-10, and FoxP3. In addition, the production of TNF-alpha by stimulated CD4(+) T cells alone or in culture with CD25(+) by itself or together with IVIg was also assessed. The presence of IVIg with Treg cells in culture significantly increased the intracellular expression of TGF-beta (17.7 +/- 8.5% vs 29.8 +/- 13%; p = 0.02), IL-10 (20.7 +/- 4.7% vs 34.2 +/- 5.2%; p = 0.008) and FoxP3 (20.8 +/- 5.2% vs 33.7 +/- 5.9%; p = 0.0006) when compared with cells cultured alone or with control human IgG. The suppressive effect of CD4(+)CD25(+) T cells presented as the decrease of TNF-alpha production by stimulated CD4(+)CD25(-) (effector T cells) was further increased by adding IVIg to cell culture. We hereby demonstrate an additional mechanism by which IVIg could maintain self-tolerance and decrease immune-mediated inflammation.
13. Winger EE, ReedJL. Low circulating CD4 (+) CD25(+) Foxp3(+) T regulatory Cells Predict Miscarriage Risk in Newly Pregnant Women with a history f failure. Am J Reprod Immunol. 2011. Feb. doi:10.1111/j.1600-0897.2011.00992.x. Problem: The purpose of this study was to determine whether quantification of peripheral blood Treg cell levels could be used as an indicator of miscarriage risk in newly pregnant women with a history of immunologic reproductive failure. Method of Study: Fifty-four pregnant women with a history of immunologic infertility and/or pregnancy loss were retrospectively evaluated (mean age: 36.7±?4.9years, 2.8±2.5 previous miscarriages; 1.5±?1.9 previous IVF failures). Twenty-three of these women experienced another first trimester miscarriage, and 31 of these women continued their current pregnancies past 12weeks ('pregnancy success'). The following immunologic parameters were assessed in the first trimester: NK cell 50:1 cytotoxicity, CD56(+) 16(+) CD3(-) (NK), CD56(+) CD3(+) (NKT), TNF/IL-10, IFN/IL-10, CD4(+) CD25(-) Foxp3(+) , total CD4(+) Foxp3(+) (CD4(+) CD25(+) Foxp3 plus CD25(-) Foxp3(+) ), and CD4(+) CD25(+) Foxp3(+) levels. Results: Patients with successful ongoing pregnancies experienced a mean (CD4(+) CD25(+) ?Foxp3(+) ) 'Treg' level of 0.72±0.52%, while those that miscarried in the first trimester experienced a mean Treg level of 0.37±?0.29% (P=0.005). Markers not significantly different between the loss and success groups were NK 50:1 cytotoxicity (P=?0.63), CD56(+) 16(+) ?3(+) NK cells (P=?0.63), CD56(+) 3(+) NKT (P=?0.30), TNF(+) IL-10(+) (P=0.13), IFNg(+) IL-10(+) (P=0.63), and CD4(+) 25(-) Foxp3(+) cells (P=0.10), although total CD4(+) Foxp3(+) levels remained significant (P=0.02) and CD4(+) 25(+) Foxp3(+) showed the most significant difference (P=0.005). Mean day of blood draw was 49.2±36.1days pregnant (median 39.0days). In addition, patients with a low Treg level (<0.7%) in the first trimester experienced a significantly lower ongoing pregnancy rate than those with a higher Treg level (>0.7%) in the first trimester [44% (15/34) versus 80% (16/20); P=0.01]. Of the 18 successful pregnancies with sequential Treg results, 85% (11/13) showed a T-regulatory-cell-level increase (mean Treg change 0.33±0.32), while only 40% (2/5) of the failed pregnancies showed a Treg increase (mean Treg change -0.08±0.28; P=0.02). Conclusions: From these data, we propose that CD4(+) CD25(+) Foxp3(+) T regulatory cells may serve as a superior pregnancy marker for assessing miscarriage risk in newly pregnant women. Larger follow-up studies are needed for confirmation.