In vitro generated CD4+CD25+ regulatory T cells efficiently prevented fetal rejection in abortion-prone mice

Journal of Reproductive Immunology 111 (2015) 10–18

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Oral Presentations

O1 In vitro generated CD4+ CD25+ regulatory T cells efficiently prevented fetal rejection in abortion-prone mice F. Idali 1,∗ , S. Rezaeenia 1,2 , R. Fatemi 1 , M.M. Naderi 3 , M. Farzi 4 , A.H. Zarnani 5 , M. Jeddi Tehrani 4 1

Reproductive Immunology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran 2 Department of Biochemistry, Science and Research Branch, Islamic Azad University, Fars, Iran 3 Reproductive Biotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran 4 Monoclonal Antibody Research Center, Avicenna Research Institute, ACECR, Tehran, Iran 5 Nanobiotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran Spontaneous resorption of the semiallogeneic fetoplacental unit in abortion-prone mice is mediated by activated immune cells and lack of functional regulatory T cells (Tregs). During pregnancy, Tregs play a major role in tolerating conceptus antigens and contribute to the maintenance of pregnancy. Here, the potential of in vitro generated Tregs in prevention of fetal rejection was investigated. Mouse spleen mononuclear cells were isolated and CD4+ T cell fractions were negatively selected and stimulated with antibodies against CD3/CD28 in the presence of either transforming growth factor (TGF-␤), 17␤-estradiol (E2) or progesterone (P4) for 4 days. The induced Tregs (iTregs) were positively selected for further experiments. Using 3 H-thymidine incorporation, suppression assays were performed. Pregnant CBA/J mice (CBA/J × DBA/2J, abortion prone) were injected intravenously with the iTregs or freshly isolated Tregs from CBA/J pregnant control mice (CBA/J × BALB/c) (2 × 105 cell per mouse) on days 1–4 of pregnancy. On day 14 of gestation, the numbers of survived/reabsorbed fetuses were counted. TGF-␤, E2 and P4 induced Foxp3 expression in CD3/CD28 challenged T cells. Purified iTregs mediated potent immunosuppression and their adoptive transfer on days 1–4 of gestation decreased fetal resorption from 50.3% ± 8.7 in abortion model to 12.6% ± 2.8, 13.4% ± 5.4 and 3.1% ± 3.1 in mice that received TGF-␤-, E2- and P4-iTregs, respectively. Fetal rejection was completely prevented by adoptive transfer of Tregs from normal pregnant mice. No significant differences were found in fetal weights. Our findings may

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provide an additional immunotherapeutic approach in prevention of abortion. http://dx.doi.org/10.1016/j.jri.2015.06.071 O2 Fetal thymus size in human pregnancies reveals inverse association with regulatory T cell frequencies in cord blood Authors K. Hecher and P. Arck jointly supervised. A. Diemert 1,∗ , I. Hartwig 1 , M. Pagenkemper 1 , R. Mehnert 1 , G. Hansen 1 , E. Tolosa 2 , K. Hecher 1 , P. Arck 1 1 Department of Obstetrics and Fetal Medicine, University Medical Center, Hamburg, Germany 2 Department of Immunology, University Medical Center, Hamburg, Germany

Objective: To derive a prediction tool for fetal immune development and rate of regulatory T cells in cord blood at birth using ultrasound measurements of the fetal thymus. Study design: Prospective pregnancy pilot cohort study PRINCE (PRenatal IdeNtification of Children’s HEalth) of singleton pregnancies from the first trimester onward until birth. Maternal history, demographics and longitudinal ultrasound assessment of fetal growth and thymus growth were compared in regard to the frequency of regulatory T cells in cord blood at delivery. Results: In 137 cases (n = 137) we observed that assessments of thymus growth at various times of gestation using the thymus transverse diameter (TTD) yielded to the lowest intra- and interobserver variability, providing the most reliable and reproducible results. We have developed longitudinal growth chart for the fetal thymus that depict the linear growth occurs. Moreover, we could establish that other factors than fetal size influence the thymus size and that the association between these two is the weakest at gestational age 28 weeks. Fetal and thymus growth correlated inversely to the frequency of regulatory T cells in cord blood. Conclusion: Ultrasound measurement of the fetal size and thymus size can be used to predict immunity at birth and the frequency of regulatory T cells in cord blood prenatally. The importance of regulatory Tcells to promote the suppression of autoreactivity toward self-antigens as well as anti-maternal immunity merits additional