AT1 receptor agonistic antibodies from preeclamptic patients stimulate NADPH oxidase

Background-We recently identified agonistic autoantibodies directed against the angiotensin AT1 receptor (AT(1)-AA) in the plasma of preeclamptic women. To elucidate their role further, we studied the effects of AT(1)-AA on reactive oxygen species (ROS), NADPH oxidase expression, and nuclear factor-kappaB (NF-kappaB) activation. Methods and Results-We investigated human vascular smooth muscle cells (VSMC) and trophoblasts, as well as placentas. AT(1)-AA were isolated from sera of preeclamptic women. Angiotensin II (Ang II) and AT(1)-AA increased ROS production and the NADPH oxidase components, p22, p47, and p67 phox in Western blotting. We next tested if AT(1)-AA lead to NF-kappaB activation in VSMC and trophoblasts. AT(1)-AA activated NF-kappaB. Inhibitor-kappaBalpha (I-kappaBalpha) expression was reduced in response to AT(1)-AA. AT1 receptor blockade with losartan, diphenylene iodonium, tiron, and antisense against p22 phox all reduced ROS production and NF-kappaB activation. VSMC from p47phox-/- mice showed markedly reduced ROS generation and NF-kappaB activation in response to Ang II and AT(1)-AA. The p22, p47, and p67 phox expression in placentas from preeclamptic patients was increased, compared with normal placentas. Furthermore, NF-kappaB was activated and I-kappaBalpha reduced in placentas from preeclamptic women. Conclusions-NADPH oxidase is potentially an important source of ROS that may upregulate NF-kappaB in preeclampsia. We suggest that AT(1)-AA through activation of NADPH oxidase could contribute to ROS production and inflammatory responses in preeclampsia.