Abstract 14844: A Novel Anti-inflammatory Mechanism of High Density LipoproteinThrough Up-regulating Annexin A1 in Vascular Endothelial Cells
Introduction: High density lipoprotein (HDL) as well as annexin A1 has been reported to be associated with cardiovascular protection. However, the correlation between HDL and annexin A1 was still unknown.
Hypothesis: HDL played an anti-inflammatory role through up-regulating Annexin A1 in vascular endothelial cells.
Methods: Cell Culture, Isolation of Lipoproteins, Western Blot, Real time PCR, Immuno-fluorescent Staining, siRNA Knockdown of ANXA1 or SRBI, Over-expression of ANXA1, Monocyte Adhesion Assay, Immunohistochemical Analysis, PepTag Assay for Nonradioactive Detection of PKC Activity, Cell Surface enzyme linked immunosorbent assay, Quantification of secreted MCP-1, IL-8, VCAM-1, and E-selectin
Results: HDL increased endothelial annexin A1 and prevented decrease of annexin A1 in TNF-α-activated endothelial cells in vitro and in vivo, and above effects were attenuated after knockdown of annexin A1. Annexin A1 modulation affected HDL-mediated inhibition of monocyte adhesion to TNF-α-activated endothelium (45.2±13.7% decrease for Annexin A1 RNA interference; 78.7±16.3% decrease for anti-Annexin A1 antibody blocking; 11.2±6.9% increase for Ad-ANXA1 transfection). Additionally, HDL upregulated annexin A1 through scavenger receptor class B type I, involving ERK, p38MAPK, Akt and PKC signaling pathways, and respective inhibitors of these pathways attenuated HDL-induced annexin A1 expression as well as impaired HDL-mediated inhibition of monocyte-endothelial cells adhesion. Apolipoprotein AI also increased annexin A1 and activated similar signaling pathways. Endothelial annexin A1 from apolipoprotein AI knockout mice was decreased in comparison to that from wild type mice. Finally, HDL-induced annexin A1 inhibited cell surface VCAM-1, ICAM-1 and E-selectin, and secretion of MCP-1, IL-8, VCAM-1 and E-selectin, thereby inhibiting monocyte adhesion.
Conclusions: This study may provide a novel understanding of HDL vascular protection and draw a novel perspective of ANXA1 in endothelial homeostasis and atherosclerosis in the future clinical research.
Author Disclosures: L. Zheng: None.
- © 2016 by American Heart Association, Inc.