Angiotensin receptor agonistic autoantibody-mediated soluble fms-like tyrosine kinase-1 induction contributes to impaired adrenal vasculature and decreased aldosterone production in preeclampsia.

Preeclampsia (PE) is a life-threatening hypertensive disorder during pregnancy associated with decreased circulating aldosterone levels. However, the molecular mechanisms underlying aldosterone reduction in PE remain unidentified. Here we demonstrate that reduced circulating aldosterone levels in preeclamptic women are associated with the presence of angiotensin II type 1 receptor agonistic autoantibody and elevated soluble Fms-like tyrosine kinase-1, 2 prominent pathogenic factors in PE. Using an adoptive transfer animal model of PE, we provide in vivo evidence that the injection of IgG from women with PE, but not IgG from normotensive individuals, resulted in hypertension, proteinuria, and a reduction in aldosterone production from 1377 ± 272 pg/mL to 544 ± 92 pg/mL (P<0.05) in pregnant mice. These features were prevented by coinjection with an epitope peptide that blocks antibody-mediated angiotensin type 1 receptor activation. In contrast, injection of IgG from preeclamptic women into nonpregnant mice induced aldosterone levels from 213 ± 24 pg/mL to 615 ± 48 pg/mL (P<0.05). These results indicate that maternal circulating autoantibody in preeclamptic women is a detrimental factor causing decreased aldosterone production via angiotensin type 1 receptor activation in a pregnancy-dependent manner. Next, we found that circulating soluble Fms-like tyrosine kinase-1 was only induced in autoantibody-injected pregnant mice but not nonpregnant mice. As such, we further observed vascular impairment in adrenal glands of pregnant mice. Finally, we demonstrated that infusion of vascular endothelial growth factor(121) attenuated autoantibody-induced adrenal gland vascular impairment resulting in a recovery in circulating aldosterone (from 544 ± 92 to 1110 ± 269 pg/mL; P<0.05). Overall, we revealed that angiotensin II type 1 receptor agonistic autoantibody-induced soluble Fms-like tyrosine kinase-1 elevation is a novel pathogenic mechanism underlying decreased aldosterone production in PE.