Abstract 18183: Alpha1-Adrenoceptor Autoantibody Mediated Vascular Endothelial Cell Injury Partially Through Macrophage Activation
Introduction: Autoantibodies against the second extracellular loop of the α1-adrenoceptor (α1-AA) exhibited sympathetic-like effects via binding to the α1-adrenoceptor, and clinical evidences showed that immunoadsorption effectively decreased the blood pressure of α1-AA positive hypertensive patients.
This present study was designed to determine whether α1-AA could cause vascular endothelial dysfunction in vivo. Furthermore, our hypothesis is to be investigated that macrophage activation may play a key role in vascular endothelial cell injury.
Methods: Rats were immunized with peptides corresponding to the second extracellular loop of α1-AR for 8 months, and the vascular endothelial function was tested in segments of thoracic aorta. α1-AA was purified from sera of patients with primary hypertension by affinity chromatography. Peritoneal macrophage was separated and cultured from rats. Effect of α1-AA (1 μM) on the migration and activity of macrophages was observed using transwell and ELISA; α1-AA induced cytotoxic and proapoptic effect on HUVEC was evaluated by LDH release and caspase-3 activity.
Results: Despite the systolic blood pressure of immunized rats having no difference with sham group, the isolated thoracic arteries showed decreased endothelium- dependent relaxation at 6 and 8 months after initial immunization(P<0.05 vs. immunized control group). α1-AA stimulated the migration and cytokines release (IL-6: 552.5± 32.38 pg/ml vs.297.4± 22.72 pg/ml, P<0.01; TNFα: 435.6 ± 27.31 pg/ml vs. 213.1± 24.52 pg/ml, P<0.01) of cultured peritoneal macrophages, which can be inhibited by selected α1-AR blocker prazosin. In the co-cultured system, macrophage pretreated with α1-AA increased LDH release (fold changes: 2.74 ± 0.27 vs. 1.00 ± 0.12, P<0.05) and caspase-3 activity (3.94 ± 0.20 nmol/h/mg protein vs. 2.72 ± 0.26 nmol/h/mg protein, P<0.05) of HUVEC, compared with that in the group of HUVEC pretreated with α1-AA.
In conclusions, long term existence of α1-AA induced vascular endothelial dysfunction in vivo. Furthermore, macrophage activation, which is an important function of adaptive immunity, contributed to the vascular endothelial injury in α1-AA positive hypertensive patients.
Author Disclosures: L. Yan: None. F. Liu: None. H. Liu: None. J. Cao: None.
- © 2016 by American Heart Association, Inc.