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Abstracts / Pregnancy Hypertension: An International Journal of Women’s Cardiovascular Health 2 (2012) 175–239
OS057. Pathophysiological role of elevated tissue transglutaminase in autoantibody-induced features of preeclampsia in pregnant mice C. Liu, W. Wang, N.F. Parchim, R.A. Irani, C. Ning, K. Sun, R.E. Kellems, Y. Xia* (Biochemistry and Molecular Biology, University of Texas Houston Medical School, Houston, United States) Introduction: Preeclampsia (PE) is highly associated with the presence of autoantibodies that activate the major angiotensin receptor, AT1R. These autoantibodies (termed AT1-AA) cause most features of PE when introduced into pregnant mice and are believed to contribute to disease pathogenesis. Tissue transglutaminase (tTG) is a prominent member of a family of enzymes that crosslink proteins by catalyzing the formation of an isopeptide bond between the amide group of glutamine and the free amino group of lysine and is believed to play a role in AT1R activation. Objectives: To test the hypothesis that tTG plays a role in autoantibody-mediated AT1R activation and thereby contributes to the pathophyhsiology of PE. Methods: Western blotting was used to quantify tTG in placentas of normotensive pregnant women and those with PE. Immunohistochemistry was used to determine cellular localization of tTG, AT1R and glutamyl-lysine isopeptides in placenta tissue. Co-immunoprecipitation experiments were used to explore the possible association of tTG and AT1R. Finally, in an effort to determine the role of tTG in AT1-AA-induced features of PE in vivo, we treated autoantibody-injected pregnant mice with cystamine, a potent tTG inhibitor. Results: Western blot analysis showed elevated tTG in placentas of women with PE. Immunohistochemical analysis revealed that increased levels of tTG, glutamyl-lysineisopeptides, AT1R co-localized in the microvillous membrane of PE placentas. Immunoprecipitation of tTG from human trophoblast cell (HTR) lysates resulted in the co-immunoprecipitation of AT1R, thereby providing evidence for an interaction between tTG and AT1R in HTR cells. Finally, we found that cystamine treatment significantly attenuated key features associated with PE including hypertension and proteinuria in the PE-IgG-injected pregnant mice. Conclusion: Taken together, we identified a previously unrecognized role of elevated tTG in PE likely by activating or stabilizing AT1Rs. These studies provide novel mechanisms of autoantibody-induced AT1R activation by elevated placental tTG, highlight the role of tTG in the pathogenesis of PE and suggest novel therapeutic strategies for the disease. Disclosure of interest None declared. doi:10.1016/j.preghy.2012.04.058
OS058. Aldosterone deficiency adversely affects pregnancy outcome in mice A. Todkar 1,*, M. Di Chiara 1, D. Loffing-Cueni 1, C. Bettoni 2, M.G. Mohaupt 3, J. Loffing 1, C. Wagner 2 (1 Institute of
Anatomy, University of Zurich, Zurich, Switzerland, Institute of Physiology, University of Zurich, Zurich, Switzerland, 3 Nephrology/Hypertension, University of Bern, Berne, Switzerland) 2
Introduction: In pregnancy, plasma volume is expanded due to high aldosterone levels to support placental perfusion and fetal nutrition. Inadequately low aldosterone levels as present in preeclampsia, a life-threatening disease for both mother and child, are discussed to be involved in its pathogenesis or severity. Objectives: We used aldosterone synthase deficient (AS / ) mice to test whether the absence of aldosterone is sufficient to impair pregnancy or even to cause preeclampsia. Methods: AS / and AS+/+ females were mated with AS+/+ and AS / males, respectively, always generating AS+/ offspring. Blood pressure was measured by tail cuff, fetal and placental number and size as well as placental histology were assessed. Placental expression of HIF-1aand angiogenic factors was assessed by semiquantitative RT-PCR. Results: With maternal aldosterone deficiency in AS / mice, systolic blood pressure was low before and further reduced during pregnancy and with no increase in proteinuria. Yet, AS / had smaller litters due to loss of fetuses as indicated by a high number of necrotic placentas with massive lymphocyte infiltrations at gestational day 18. Surviving fetuses and their placentas from AS / females were smaller. High salt diet before and during pregnancy increased systolic blood pressure only before pregnancy in both genotypes and reduced blood pressure during late pregnancy as compared to normal salt controls. Litter size from AS / was slightly improved and the differences in placental and fetal weights between AS+/+ and AS / mothers disappeared. Overall an increased placental efficiency was observed in both groups. Conclusion: Our results demonstrate that aldosterone deficiency has profound adverse effects on placental function. High dietary salt intake improved placental function and lowered blood pressure in wild-type mice. In this animal model, aldosterone deficiency did not cause preeclampsia. Disclosure of interest None declared. doi:10.1016/j.preghy.2012.04.059
OS059. Blockade of the bradykinin B2 receptor in early pregnancy reduces fetal growth and trophoblast invasion in guinea-pigs G. Valdes 1,2,*, D. Schneider 1, J. Corthorn 1,2, R. Ortiz 1 (1 Centro Investigaciones Medicas, Escuela Medicina Pontificia Universidad Católica, Santiago, Chile, 2 Nephrology, Escuela Medicina Pontificia Universidad Católica, Santiago, Chile) Introduction: Research in preeclampsia (PE) is hampered by the difficulty of sampling the placental bed in early pregnancies followed to delivery to be defined as normal or pre-
Abstracts / Pregnancy Hypertension: An International Journal of Women’s Cardiovascular Health 2 (2012) 175–239
OS057. Pathophysiological role of elevated tissue transglutaminase in autoantibody-induced features of preeclampsia in pregnant mice C. Liu, W. Wang, N.F. Parchim, R.A. Irani, C. Ning, K. Sun, R.E. Kellems, Y. Xia* (Biochemistry and Molecular Biology, University of Texas Houston Medical School, Houston, United States) Introduction: Preeclampsia (PE) is highly associated with the presence of autoantibodies that activate the major angiotensin receptor, AT1R. These autoantibodies (termed AT1-AA) cause most features of PE when introduced into pregnant mice and are believed to contribute to disease pathogenesis. Tissue transglutaminase (tTG) is a prominent member of a family of enzymes that crosslink proteins by catalyzing the formation of an isopeptide bond between the amide group of glutamine and the free amino group of lysine and is believed to play a role in AT1R activation. Objectives: To test the hypothesis that tTG plays a role in autoantibody-mediated AT1R activation and thereby contributes to the pathophyhsiology of PE. Methods: Western blotting was used to quantify tTG in placentas of normotensive pregnant women and those with PE. Immunohistochemistry was used to determine cellular localization of tTG, AT1R and glutamyl-lysine isopeptides in placenta tissue. Co-immunoprecipitation experiments were used to explore the possible association of tTG and AT1R. Finally, in an effort to determine the role of tTG in AT1-AA-induced features of PE in vivo, we treated autoantibody-injected pregnant mice with cystamine, a potent tTG inhibitor. Results: Western blot analysis showed elevated tTG in placentas of women with PE. Immunohistochemical analysis revealed that increased levels of tTG, glutamyl-lysineisopeptides, AT1R co-localized in the microvillous membrane of PE placentas. Immunoprecipitation of tTG from human trophoblast cell (HTR) lysates resulted in the co-immunoprecipitation of AT1R, thereby providing evidence for an interaction between tTG and AT1R in HTR cells. Finally, we found that cystamine treatment significantly attenuated key features associated with PE including hypertension and proteinuria in the PE-IgG-injected pregnant mice. Conclusion: Taken together, we identified a previously unrecognized role of elevated tTG in PE likely by activating or stabilizing AT1Rs. These studies provide novel mechanisms of autoantibody-induced AT1R activation by elevated placental tTG, highlight the role of tTG in the pathogenesis of PE and suggest novel therapeutic strategies for the disease. Disclosure of interest None declared. doi:10.1016/j.preghy.2012.04.058
OS058. Aldosterone deficiency adversely affects pregnancy outcome in mice A. Todkar 1,*, M. Di Chiara 1, D. Loffing-Cueni 1, C. Bettoni 2, M.G. Mohaupt 3, J. Loffing 1, C. Wagner 2 (1 Institute of
Anatomy, University of Zurich, Zurich, Switzerland, Institute of Physiology, University of Zurich, Zurich, Switzerland, 3 Nephrology/Hypertension, University of Bern, Berne, Switzerland) 2
Introduction: In pregnancy, plasma volume is expanded due to high aldosterone levels to support placental perfusion and fetal nutrition. Inadequately low aldosterone levels as present in preeclampsia, a life-threatening disease for both mother and child, are discussed to be involved in its pathogenesis or severity. Objectives: We used aldosterone synthase deficient (AS / ) mice to test whether the absence of aldosterone is sufficient to impair pregnancy or even to cause preeclampsia. Methods: AS / and AS+/+ females were mated with AS+/+ and AS / males, respectively, always generating AS+/ offspring. Blood pressure was measured by tail cuff, fetal and placental number and size as well as placental histology were assessed. Placental expression of HIF-1aand angiogenic factors was assessed by semiquantitative RT-PCR. Results: With maternal aldosterone deficiency in AS / mice, systolic blood pressure was low before and further reduced during pregnancy and with no increase in proteinuria. Yet, AS / had smaller litters due to loss of fetuses as indicated by a high number of necrotic placentas with massive lymphocyte infiltrations at gestational day 18. Surviving fetuses and their placentas from AS / females were smaller. High salt diet before and during pregnancy increased systolic blood pressure only before pregnancy in both genotypes and reduced blood pressure during late pregnancy as compared to normal salt controls. Litter size from AS / was slightly improved and the differences in placental and fetal weights between AS+/+ and AS / mothers disappeared. Overall an increased placental efficiency was observed in both groups. Conclusion: Our results demonstrate that aldosterone deficiency has profound adverse effects on placental function. High dietary salt intake improved placental function and lowered blood pressure in wild-type mice. In this animal model, aldosterone deficiency did not cause preeclampsia. Disclosure of interest None declared. doi:10.1016/j.preghy.2012.04.059
OS059. Blockade of the bradykinin B2 receptor in early pregnancy reduces fetal growth and trophoblast invasion in guinea-pigs G. Valdes 1,2,*, D. Schneider 1, J. Corthorn 1,2, R. Ortiz 1 (1 Centro Investigaciones Medicas, Escuela Medicina Pontificia Universidad Católica, Santiago, Chile, 2 Nephrology, Escuela Medicina Pontificia Universidad Católica, Santiago, Chile) Introduction: Research in preeclampsia (PE) is hampered by the difficulty of sampling the placental bed in early pregnancies followed to delivery to be defined as normal or pre-
