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The detrimental role of angiotensin receptor agonistic autoantibodies in intrauterine growth restriction seen in preeclampsia.

Irani RA, Zhang Y, Blackwell SC, Zhou CC, Ramin SM, Kellems RE, Xia Y - J. Exp. Med. (2009)

Bottom Line: Recently, emerging evidence indicates that preeclamptic women harbor AT(1) receptor agonistic autoantibodies (AT(1)-AAs) that contribute to the disease features.Thus, these studies identify AT(1)-AA as a novel causative factor of preeclampsia-associated IUGR and offer two possible underlying mechanisms: a direct detrimental effect on fetal development by crossing the placenta and entering fetal circulation, and indirectly through AT(1)-AA-induced placental damage.Our findings highlight AT(1)-AAs as important therapeutic targets.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biochemistry and Molecular Biology, University of Texas Medical School at Houston, Houston, TX, 77030, USA.

ABSTRACT
Growth-restricted fetuses are at risk for a variety of lifelong medical conditions. Preeclampsia, a life-threatening hypertensive disorder of pregnancy, is associated with fetuses who suffer from intrauterine growth restriction (IUGR). Recently, emerging evidence indicates that preeclamptic women harbor AT(1) receptor agonistic autoantibodies (AT(1)-AAs) that contribute to the disease features. However, the exact role of AT(1)-AAs in IUGR and the underlying mechanisms have not been identified. We report that these autoantibodies are present in the cord blood of women with preeclampsia and retain the ability to activate AT(1) receptors. Using an autoantibody-induced animal model of preeclampsia, we show that AT(1)-AAs cross the mouse placenta, enter fetal circulation, and lead to small fetuses with organ growth retardation. AT(1)-AAs also induce apoptosis in the placentas of pregnant mice, human villous explants, and human trophoblast cells. Finally, autoantibody-induced IUGR and placental apoptosis are diminished by either losartan or an autoantibody-neutralizing peptide. Thus, these studies identify AT(1)-AA as a novel causative factor of preeclampsia-associated IUGR and offer two possible underlying mechanisms: a direct detrimental effect on fetal development by crossing the placenta and entering fetal circulation, and indirectly through AT(1)-AA-induced placental damage. Our findings highlight AT(1)-AAs as important therapeutic targets.

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AT1-AAs can pass through the human placenta and retain biological activity in fetal circulation. (A and B) Autoantibodies detected by Western blot in the sera of preeclamptic women could also be found in cord blood (A). Cellular lysate from CHO.AT1A cells containing stably integrated copies of a minigene encoding the AT1 receptor was run on a 10% SDS-PAGE gel and transferred to a nitrocellulose membrane. The AT1 receptor–rich membrane was cut into strips and each strip was individually probed by either an anti–AT1 receptor antibody (control), or purified antibodies derived from maternal serum or cord blood from normotensive (n = 6) or preeclamptic (n = 6) pregnancies. Also, to specifically detect AT1-AAs from the total IgG pool, an affinity purification strategy was used. The flow-through and eluted affinity-purified fractions of IgGs derived from the cord blood of babies from preeclamptic patients were also tested for their ability to bind to the AT1 receptor (n = 6). Only preeclamptic maternal sera, cord blood from babies of preeclamptic women, and the eluted affinity-purified fraction harbored autoantibodies recognizing the AT1 receptor at 43 kD. Then, cord blood IgGs were tested for biological activity (B) using an in vitro luciferase activity assay that is increased secondary to AT1 receptor activation. Only IgGs purified from the cord blood of babies from preeclamptic patients or the eluted affinity-purified fraction induced luciferase activity. This bioactivity could be blocked by co-culturing the reporter cell line with IgG derived from preeclamptic patients and losartan or the 7-aa epitope peptide (n = 5 for each variable in two independent experiments). Data are expressed as means ± SEM. *, P < 0.01 versus IgG derived from cord blood of a normotensive patient; **, P < 0.01 versus IgG derived from cord blood of a preeclamptic patient; +, P < 0.01 versus flow-through affinity-purified fraction. NT, normotensive; PE, preeclampsia.
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fig1: AT1-AAs can pass through the human placenta and retain biological activity in fetal circulation. (A and B) Autoantibodies detected by Western blot in the sera of preeclamptic women could also be found in cord blood (A). Cellular lysate from CHO.AT1A cells containing stably integrated copies of a minigene encoding the AT1 receptor was run on a 10% SDS-PAGE gel and transferred to a nitrocellulose membrane. The AT1 receptor–rich membrane was cut into strips and each strip was individually probed by either an anti–AT1 receptor antibody (control), or purified antibodies derived from maternal serum or cord blood from normotensive (n = 6) or preeclamptic (n = 6) pregnancies. Also, to specifically detect AT1-AAs from the total IgG pool, an affinity purification strategy was used. The flow-through and eluted affinity-purified fractions of IgGs derived from the cord blood of babies from preeclamptic patients were also tested for their ability to bind to the AT1 receptor (n = 6). Only preeclamptic maternal sera, cord blood from babies of preeclamptic women, and the eluted affinity-purified fraction harbored autoantibodies recognizing the AT1 receptor at 43 kD. Then, cord blood IgGs were tested for biological activity (B) using an in vitro luciferase activity assay that is increased secondary to AT1 receptor activation. Only IgGs purified from the cord blood of babies from preeclamptic patients or the eluted affinity-purified fraction induced luciferase activity. This bioactivity could be blocked by co-culturing the reporter cell line with IgG derived from preeclamptic patients and losartan or the 7-aa epitope peptide (n = 5 for each variable in two independent experiments). Data are expressed as means ± SEM. *, P < 0.01 versus IgG derived from cord blood of a normotensive patient; **, P < 0.01 versus IgG derived from cord blood of a preeclamptic patient; +, P < 0.01 versus flow-through affinity-purified fraction. NT, normotensive; PE, preeclampsia.

Mentions: The placenta is a massive vascular organ that brings maternal and fetal circulatory systems into close proximity, facilitating the nutrient and gas exchange essential for fetal development (Georgiades et al., 2002). Maternal blood is supplied to the placenta via the uterine spiral arteries, and the fetus receives blood from the vessels present in the umbilical cord. Cord blood therefore represents a convenient source of fetal blood that is easily obtained at the time of parturition. To determine if AT1-AAs cross from the maternal to fetal circulation during pregnancy, we obtained maternal and cord blood from normotensive pregnant women and women with preeclampsia. Total IgG was isolated from serum and examined for the presence of AT1-AAs. The results of the Western blot (Fig. 1 A) show that total IgGs from maternal and cord sera of women with preeclampsia detected a band of 43 kD, corresponding to the AT1 receptor derived from cellular lysates enriched with the receptor that were transferred to a nitrocellulose membrane. In contrast, IgG from maternal and cord sera of women with normotensive pregnancies did not cross react with a protein of 43 kD (Fig. 1 A). To further confirm this result, an affinity chromatography strategy was used to specifically isolate AT1-AAs from the cord blood of fetuses from women with preeclampsia. The Western blot indicates that only the eluted fraction (AT1-AAs) could detect a band at 43 kD, corresponding to the AT1 receptor, whereas the flow-through fraction did not. These findings suggest that specific IgGs from women with preeclampsia that bind to the AT1 receptor can cross the placenta and enter the fetal circulation.


The detrimental role of angiotensin receptor agonistic autoantibodies in intrauterine growth restriction seen in preeclampsia.

Irani RA, Zhang Y, Blackwell SC, Zhou CC, Ramin SM, Kellems RE, Xia Y - J. Exp. Med. (2009)

AT1-AAs can pass through the human placenta and retain biological activity in fetal circulation. (A and B) Autoantibodies detected by Western blot in the sera of preeclamptic women could also be found in cord blood (A). Cellular lysate from CHO.AT1A cells containing stably integrated copies of a minigene encoding the AT1 receptor was run on a 10% SDS-PAGE gel and transferred to a nitrocellulose membrane. The AT1 receptor–rich membrane was cut into strips and each strip was individually probed by either an anti–AT1 receptor antibody (control), or purified antibodies derived from maternal serum or cord blood from normotensive (n = 6) or preeclamptic (n = 6) pregnancies. Also, to specifically detect AT1-AAs from the total IgG pool, an affinity purification strategy was used. The flow-through and eluted affinity-purified fractions of IgGs derived from the cord blood of babies from preeclamptic patients were also tested for their ability to bind to the AT1 receptor (n = 6). Only preeclamptic maternal sera, cord blood from babies of preeclamptic women, and the eluted affinity-purified fraction harbored autoantibodies recognizing the AT1 receptor at 43 kD. Then, cord blood IgGs were tested for biological activity (B) using an in vitro luciferase activity assay that is increased secondary to AT1 receptor activation. Only IgGs purified from the cord blood of babies from preeclamptic patients or the eluted affinity-purified fraction induced luciferase activity. This bioactivity could be blocked by co-culturing the reporter cell line with IgG derived from preeclamptic patients and losartan or the 7-aa epitope peptide (n = 5 for each variable in two independent experiments). Data are expressed as means ± SEM. *, P < 0.01 versus IgG derived from cord blood of a normotensive patient; **, P < 0.01 versus IgG derived from cord blood of a preeclamptic patient; +, P < 0.01 versus flow-through affinity-purified fraction. NT, normotensive; PE, preeclampsia.
© Copyright Policy - openaccess
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2806612&req=5

fig1: AT1-AAs can pass through the human placenta and retain biological activity in fetal circulation. (A and B) Autoantibodies detected by Western blot in the sera of preeclamptic women could also be found in cord blood (A). Cellular lysate from CHO.AT1A cells containing stably integrated copies of a minigene encoding the AT1 receptor was run on a 10% SDS-PAGE gel and transferred to a nitrocellulose membrane. The AT1 receptor–rich membrane was cut into strips and each strip was individually probed by either an anti–AT1 receptor antibody (control), or purified antibodies derived from maternal serum or cord blood from normotensive (n = 6) or preeclamptic (n = 6) pregnancies. Also, to specifically detect AT1-AAs from the total IgG pool, an affinity purification strategy was used. The flow-through and eluted affinity-purified fractions of IgGs derived from the cord blood of babies from preeclamptic patients were also tested for their ability to bind to the AT1 receptor (n = 6). Only preeclamptic maternal sera, cord blood from babies of preeclamptic women, and the eluted affinity-purified fraction harbored autoantibodies recognizing the AT1 receptor at 43 kD. Then, cord blood IgGs were tested for biological activity (B) using an in vitro luciferase activity assay that is increased secondary to AT1 receptor activation. Only IgGs purified from the cord blood of babies from preeclamptic patients or the eluted affinity-purified fraction induced luciferase activity. This bioactivity could be blocked by co-culturing the reporter cell line with IgG derived from preeclamptic patients and losartan or the 7-aa epitope peptide (n = 5 for each variable in two independent experiments). Data are expressed as means ± SEM. *, P < 0.01 versus IgG derived from cord blood of a normotensive patient; **, P < 0.01 versus IgG derived from cord blood of a preeclamptic patient; +, P < 0.01 versus flow-through affinity-purified fraction. NT, normotensive; PE, preeclampsia.
Mentions: The placenta is a massive vascular organ that brings maternal and fetal circulatory systems into close proximity, facilitating the nutrient and gas exchange essential for fetal development (Georgiades et al., 2002). Maternal blood is supplied to the placenta via the uterine spiral arteries, and the fetus receives blood from the vessels present in the umbilical cord. Cord blood therefore represents a convenient source of fetal blood that is easily obtained at the time of parturition. To determine if AT1-AAs cross from the maternal to fetal circulation during pregnancy, we obtained maternal and cord blood from normotensive pregnant women and women with preeclampsia. Total IgG was isolated from serum and examined for the presence of AT1-AAs. The results of the Western blot (Fig. 1 A) show that total IgGs from maternal and cord sera of women with preeclampsia detected a band of 43 kD, corresponding to the AT1 receptor derived from cellular lysates enriched with the receptor that were transferred to a nitrocellulose membrane. In contrast, IgG from maternal and cord sera of women with normotensive pregnancies did not cross react with a protein of 43 kD (Fig. 1 A). To further confirm this result, an affinity chromatography strategy was used to specifically isolate AT1-AAs from the cord blood of fetuses from women with preeclampsia. The Western blot indicates that only the eluted fraction (AT1-AAs) could detect a band at 43 kD, corresponding to the AT1 receptor, whereas the flow-through fraction did not. These findings suggest that specific IgGs from women with preeclampsia that bind to the AT1 receptor can cross the placenta and enter the fetal circulation.

Bottom Line: Recently, emerging evidence indicates that preeclamptic women harbor AT(1) receptor agonistic autoantibodies (AT(1)-AAs) that contribute to the disease features.Thus, these studies identify AT(1)-AA as a novel causative factor of preeclampsia-associated IUGR and offer two possible underlying mechanisms: a direct detrimental effect on fetal development by crossing the placenta and entering fetal circulation, and indirectly through AT(1)-AA-induced placental damage.Our findings highlight AT(1)-AAs as important therapeutic targets.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biochemistry and Molecular Biology, University of Texas Medical School at Houston, Houston, TX, 77030, USA.

ABSTRACT
Growth-restricted fetuses are at risk for a variety of lifelong medical conditions. Preeclampsia, a life-threatening hypertensive disorder of pregnancy, is associated with fetuses who suffer from intrauterine growth restriction (IUGR). Recently, emerging evidence indicates that preeclamptic women harbor AT(1) receptor agonistic autoantibodies (AT(1)-AAs) that contribute to the disease features. However, the exact role of AT(1)-AAs in IUGR and the underlying mechanisms have not been identified. We report that these autoantibodies are present in the cord blood of women with preeclampsia and retain the ability to activate AT(1) receptors. Using an autoantibody-induced animal model of preeclampsia, we show that AT(1)-AAs cross the mouse placenta, enter fetal circulation, and lead to small fetuses with organ growth retardation. AT(1)-AAs also induce apoptosis in the placentas of pregnant mice, human villous explants, and human trophoblast cells. Finally, autoantibody-induced IUGR and placental apoptosis are diminished by either losartan or an autoantibody-neutralizing peptide. Thus, these studies identify AT(1)-AA as a novel causative factor of preeclampsia-associated IUGR and offer two possible underlying mechanisms: a direct detrimental effect on fetal development by crossing the placenta and entering fetal circulation, and indirectly through AT(1)-AA-induced placental damage. Our findings highlight AT(1)-AAs as important therapeutic targets.

Show MeSH
Related in: MedlinePlus