Antigen-specific Treg are generated very early in pregnancy

Antigen-specific Treg are generated very early in pregnancy

Abstracts / Journal of Reproductive Immunology 71 (2006) 135–176 On day 24 of gestation decidualized endometrial stromal cells become an extensive la...

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Abstracts / Journal of Reproductive Immunology 71 (2006) 135–176

On day 24 of gestation decidualized endometrial stromal cells become an extensive layer beneath the implantation site in Untreated control and Non-specific treated groups. In 25D3-treated monkeys distribution of the decidual cells was patchy. Small arteries directly beneath the implantation site were completely occluded by EVCT in all groups of animals. The arterial endothelial layer in all groups and the tunica media in Untreated control and Non-specific treated groups was breached over much of its circumference. In 25D3-treated placentas the tunica media of the decidual spiral arteries remained intact. Macrophages (CD68-positive) and CD56-positive NK cells abundantly infiltrated deciduas in all groups of animals. DC-SIGN-positive cell distribution in decidua was significantly lower in anti-MamuAG passive immunized monkeys compared to Untreated control and Non-specific-treated groups. In Untreated control and Non-specific treated groups there were a few isolated CD3-positive cells, whereas in 25D3-treated animals, CD3+ cells in formed a dense infiltrate around non-invaded vessels. In addition, we noted a decrease in the villous length and diameter, the number of vessels within the villous stroma in 25D3-treated animals in comparison with Control group. We propose that the anti-Mamu-AG-passive immunization inhibits trophoblastic modification of maternal vessels, and local immune response, suggests an important interaction between placental MHC class I expression and the an appropriate environment for placental development and trophoblast invasion in primate pregnancy. Keywords: Decidua

MHC; Dendritic cells; Lymphocytes;

are believed to be caused by failed transformation of the spiral arteries. Confluent monolayers of HMEC-1 endothelial cells were grown on microscope slides and labelled with green fluorescent cell tracker stain. Jar choriocarcinoma cells were used as a model of invasive trophoblasts and labelled with red fluorescent cell tracker stain. The monolayers of HMEC-1 cells were activated by incubation with TNF alpha (20 ng/ml) or INF gamma (10 ng/ml) then the labelled Jar cells were added. After 24 h the formation of Jar cell “islands” in endothelial monolayers was observed by confocal microscopy and quantified by digital image analysis using our published method [1]. Cell-based ELISAs detecting ICAM-1 confirmed that that the doses of TNF alpha and INF gamma used activated the endothelial cells. The Jar cell “islands” formed in endothelial cell monolayers treated with either TNF alpha or INF gamma were significantly smaller than the Jar cell “islands” formed in control untreated endothelial cell monolayers. That activated endothelial cells are able to resist invasion by trophoblasts in this in vitro model suggests that a similar effect may occur in vivo and excess TNF alpha, INF gamma or other activators of endothelial cells at the maternofetal interface might in part explain the reduced invasion of the spiral arteries seen in preeclampsia and intrauterine growth restriction. Reference Chen, Q., Stone, P.R., McCowan, Chamley, L.W., 2005. Interactions of Jar choriocarcinoma cells with endothelial cell monolayers. Placenta 26, 617–625.

doi:10.1016/j.jri.2006.08.023

Keywords: Preeclampsia

[O8] Activated endothelial cells resist invasion by trophoblasts

doi:10.1016/j.jri.2006.08.024

Q. Chen, P. Stone, L. Chamley University of Auckland, New Zealand During normal human pregnancy, extravillous trophoblasts invade the maternal spiral arteries replacing the endothelial cell that normal line these vessels and degrading the musculo-elastic walls of the vessels such that they are transformed into wide-bore, low resistance conduits. This modification of the spiral arteries is essential to ensure an adequate supply of blood to the placenta during later pregnancy and two complications of pregnancy, preeclampsia and intra-uterine growth restriction,

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Cytokines;

Implantation;

Placenta;

[O9] Antigen-specific Treg are generated very early in pregnancy A.C. Zenclussen , C. Thuere, J. Leber, A. Schumacher, M.L. Zenclussen, P. Wafula, H.-D. Volk Charit´e Medical University of Berlin, Germany The survival of the semiallogeneic fetus within the mother is thought to be due to mechanisms of immunological tolerance. Regulatory T cells (Treg) are believed to have a crucial role in maintaining pregnancy by creating a transient tolerant microenvironment within the maternal uterus as former studies confirmed. They

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Abstracts / Journal of Reproductive Immunology 71 (2006) 135–176

also seem to act in an antigen-specific manner. Here, we investigate the kinetics of Tregs during pregnancy (day 0, 2, 5, 8, 10 or 12 of pregnancy) in abortionprone mice (DBA/2J-mated CBA/J females) and control animals (BALB/c-mated CBA/J animals). We further focussed on the site of generation and characteristics of pregnancy-induced Treg. Our data showed increased levels of Treg in lymph nodes already very early in normal pregnancy and confirmed diminished numbers of Treg within abortionprone mice. An enormous augmentation in the number of TCR␣␤+ CD4− CD8− foxp3+ cells in vaginal mucus from normal pregnant animals already on day 0.5 after conception, followed by an increase in Treg numbers in lymph nodes, suggest that Treg need to be activated by male antigens for being protective. The antigen presentation would take place in the periphery e.g. in vaginal mucus, the first site of contact with paternal antigens, directly after insemination as we could confirm by identifying paternal antigens and paternal APCs at this site. This explains previous observations on Treg transfer being effective in preventing abortion if done on days 0–2 of pregnancy but not later. Interestingly, mating CBA/J females with vasectomized BALB/c males generated foxp3+ cells in lymph nodes draining the uterus, while pseudopregnancy induced by mechanical stimulation did not. Treg-induced tolerance is transient, as Treg came back to the normal levels after the disappearance of the paternal/fetal antigens, 14 days post-partum. Our results suggest the crucial role of Tregs already shortly after conception. Keywords: Treg; Vaginal mucus; Tolerance; Pregnancy doi:10.1016/j.jri.2006.08.025 [O10] Male seminal constituents activate expansion of the T regulatory cell pool in early pregnancy S.A. Robertson , L.R. Guerin, J.J. Bromfield University of Adelaide, Australia T regulatory (Treg) cells are implicated as key mediators of the maternal immune tolerance required to accommodate semi-allogeneic pregnancy in mice. These cells increase in number in the uterine draining lymph nodes and spleen during the four day interval between conception and embryo implantation [1], however the processes driving this early expansion are unknown. Male seminal fluid introduced at mating activates immune changes in the female tract, providing pro-inflammatory and antigenic signals that elicit antigen-presenting cell

recruitment into the uterine endometrium, resulting in activation and expansion of T-lymphocytes in the paraaortic lymph nodes (PALN) [2], and a transient state of functional immune tolerance for paternal MHC antigens in the periphery [3]. To examine the potential role of seminal fluids in eliciting Treg cell expansion during early pregnancy, we evaluated CD4+CD25+ cells in PALN of C57Bl/6 female mice mated with Balb/c males. On day 4 after mating with intact males (day 4 pc), PALN cell number was increased 2.1-fold compared with virgin mice, with no change in the relative proportions of T- and Blymphocytes. CD4+CD25+ cells comprised 11.3% of the total CD4+ population compared with 7.3% in virgin mice, reflecting a 3.2-fold expansion in the CD4+CD25+ cell pool (p < 0.001). Essentially all PALN CD4+CD25+ cells were positive for the signature Treg cell transcription factor Foxp3 in both virgin and mated mice, and a >2-fold increase in Foxp3 mRNA expression was seen by quantitative RT-PCR in the lymph nodes and uterus of day 4 pc mice compared with virgin controls. Although lymph node hypertrophy was also evident in mice mated with vasectomised males, there was no increase in the PALN CD4+CD25+ cell pool and no increase in Foxp3 mRNA expression. In mice mated with males from which the seminal vesicles were surgically removed, lymph node hypertrophy did not occur and no increase in the PALN CD4+CD25+ cell pool or Foxp3 mRNA expression was evident. Together these data provide evidence that exposure to seminal fluid at mating triggers activation and expansion of Treg cell populations in the regional lymph nodes and uterus, providing a mechanism for the early expansion in Treg cells required to facilitate maternal immune tolerance of the conceptus at implantation. Both sperm and seminal plasma components of the seminal fluid appear to be necessary to elicit the early Treg cell response, presumably through provision of antigenic and immunedeviating signals including TGF␤, respectively. References Aluvihare, V.R., et al., 2004. Nat Immunol 5, 266–271. Johansson, M., et al., 2004. Immunology 112, 290–300. Robertson, S.A., et al., 1997. Am J Reprod Immunol 37, 438–442.

Keywords: Tolerance; Pregnancy; Sperm doi:10.1016/j.jri.2006.08.026