Blockade of endogenous angiotensin II type I receptor agonistic autoantibody activity improves mitochondrial reactive oxygen species and hypertension in a rat model of preeclampsia

Preeclampsia (PE) is characterized by new-onset hypertension that usually occurs in the third trimester of pregnancy and is associated with oxidative stress and angiotensin II type 1 receptor agonistic autoantibodies (AT₁-AAs). Inhibition of the AT₁-AAs in the reduced uterine perfusion pressure (RUPP) rat, a model of PE, attenuates hypertension and many other characteristics of PE. We have previously shown that mitochondrial oxidative stress (mtROS) is a newly described PE characteristic exhibited by the RUPP rat that contributes to hypertension. However, the factors that cause mtROS in PE or RUPP are unknown. Thus, the objective of the current study is to use pharmacologic inhibition of AT₁-AAs to examine their role in mtROS in the RUPP rat model of PE. AT₁-AA inhibition in RUPP rats was achieved by administration of an epitope-binding peptide (=n7AAc=). Female Sprague-Dawley rats were divided into the following two groups: RUPP and RUPP + AT₁-AA inhibition (RUPP + =n7AAc=). On day 14 of gestation (GD), RUPP surgery was performed; =n7AAc= peptide (2 μg/μL) was administered by miniosmotic pumps in a subset of RUPP rats; and on GD19, sera, placentas, and kidneys were collected. mitochondrial respiration and mtROS were measured in isolated mitochondria using the Oxygraph 2K and fluorescent microplate reader, respectively. Placental and renal mitochondrial respiration and mtROS were improved in RUPP + =n7AAc= rats compared with RUPP controls. Moreover, endothelial cells (human umbilical vein endothelial cells) treated with RUPP + =n7AAc= sera exhibited less mtROS compared with those treated with RUPP sera. Overall, our findings suggest that AT₁-AA signaling is one stimulus of mtROS during PE.