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Agonistic Autoantibodies to the Angiotensin II Type 1 Receptor Enhance ANGII Binding on Vascular Endothelial Cells
Author(s) -
Cunningham Mark,
Faulkner Jessica,
Amaral Lorena,
Cornelius Denise,
Kramer Robert,
LaMarca Babbette
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.810.12
Subject(s) - losartan , angiotensin ii receptor type 1 , angiotensin ii , chemistry , medicine , endocrinology , receptor , renin–angiotensin system , umbilical vein , biochemistry , blood pressure , in vitro
Preeclamptic women produce agonistic autoantibodies to the Angiotensin II type 1 receptor (AT1‐AA) and exhibit increased sensitivity to angiotensin II (ANG II). Together, AT1‐AA and ANGII increased blood pressure, endothelin‐1 (ET‐1), oxidative stress in pregnant rats. However, cellular mechanisms for such responses remain unknown. Our objective in this study was to examine the effect of AT1‐AA on ANGII binding to the AT1 receptor on human vascular umbilical endothelial cells (HUVEC) and the subsequent release of ET‐1. Methods: HUVECs were incubated for 1 hour with FITC labelled ANGII (10nM, 50nM, 100nM and 200nM) with or without AT1‐AA (1:100), losartan [LOS (10µM)], or a specific inhibitor of AT1‐AAs [7AA(5µg/ml)]. ANGII binding was determined by FITC labeled ANGII florescence at 490nm excitation and 522nm emission wavelengths and ET‐1 was measured by ELISA. Results: At 1 hour incubation, bound ANG II to AT1 R was approximately 1.0+/‐0.11 and 5.2±1.3 pmols/mg at 100 and 200 nM concentrations, which drastically increased with the AT1‐AA to 20+/‐5 and 65+/‐3, and was decreased with AT1‐AA inhibitory peptide (40 +/‐3 at the 200nM ANGII) and losartan. Interestingly, AT1‐AA induced a 2‐fold increase in ET‐1 above that with ANGII alone at physiological doses of 10nM and 50nM, which sharply declined at higher doses of ANGII (100, 200 & 500nM). Conclusion AT1‐AA greatly increases the binding affinity of ANGII for the AT1 R on HUVECs and secretion of ET‐1 at physiological ANGII concentrations supporting a role for the AT1‐AA to enhance ANGII effects during preeclampsia.