Angiotensin II Type I Receptor Agonistic Autoantibody Blockade Improves Cerebral Blood Flow Autoregulation, Blood Brain Barrier Permeability, and Hypertension in the Pre‐Clinical Rat Model of Preeclampsia

Abstract

Background Preeclampsia (PE) is a pregnancy disorder that is characterized by an increase in blood pressure, angiotensin II type1 receptor agonistic autoantibodies (AT1‐AA), and neurological complications. The pre‐clinical RUPP (reduced uterine perfusion pressure) rat model of PE displays many of the clinical pathologies associated with PE, such as increased blood pressure, AT1‐AAs, blood brain barrier (BBB) permeability, and impaired cerebral blood flow (CBF) autoregulation. Hypothesis We hypothesized that specific inhibition of AT1‐AA, using the epitope binding 7 amino acid peptide sequence (7AA), will improve blood pressure, BBB integrity, and CBF autoregulation in RUPP rats. Methods Sprague Dawley rats, were divided into 3 groups: normal pregnant (NP) (n=19), RUPP (n=19), and RUPP+AT1‐AA inhibition (7AA) (n=21). RUPP surgery was performed on gestational day (GD) 14 and 7AA (2μg/μl) was administered via osmotic minipumps. GD 19, mean arterial pressure (MAP) was determined and BBB permeability was assessed using the in‐vivo imaging system (IVIS). CBF was measured by laser Doppler flowmetry through a 4 mm x 4 mm cranial window under anesthesia. MAP was elevated step‐wise from 100–190 mmHg by infusion of phenylephrine to determine changes in CBF. Results MAP was increased in RUPP vs NP (124±3 vs 100±1 mmHg, p<0.05) and decreased in RUPP+7AA vs RUPP (105±2 vs 124±3 mmHg, p<0.05) rats. Using IVIS, Texas Red/FITC green fluorescent imaging was decreased in RUPP+7AA vs RUPP (0.2±0.001 vs 0.6±0.001, p<0.05), indicating improvement in BBB permeability with AT1‐AA inhibition. CBF autoregulation was impaired in RUPP vs NP rats at 140 mmHg (142±7 vs 119±4%, p<0.05) and 160 mmHg (157±10 vs 129±6%, p<0.05) (both pressures are within the normal CBF autoregulatory range). AT1‐AA inhibition prevented impaired CBF at 140mmHg (125±5 RUPP+7AA vs 142±7% RUPP, p<0.05) and 160 mmHg (125±9 RUPP+7AA vs 157±10% RUPP, p<0.05). Furthermore, the increases in CBF at pressures above the autoregulatory range, 180 mmHg (122±10 vs 198±17%, p<0.05) and 190 mmHg (123±11 vs 208±19%, p<0.05), was prevented in RUPP+7AA vs RUPP, respectively. Conclusion AT1‐AA inhibition improved blood pressure, BBB permeability, and CBF autoregulation in the pre‐clinical RUPP rat model of PE, indicating that AT1‐AA inhibition may be a potential therapy used to improve neurological complications during PE. Support or Funding Information Supported: AHA18CDA34110264