Abstract 179: Atheroprone Hemodynamics and Oxidized Phospholipids Enhance Endothelial and Smooth Muscle Inflammatory Signaling
Atherosclerosis is a focal inflammatory disease marked by activation of NFkB within regions where low and oscillating shear stresses (Atheroprone) “prime” the endothelium for an inflammatory response. Interestingly, oxPAPC, a major component of oxLDL, has not been shown to act through the canonical NFkB pathway, and although oxLDL is capable of increasing the expression of NFkB-dependent genes it often requires higher concentrations of oxLDL (>100ug/ml). Further, these studies were all performed within static monocultures, where the endothelium was not a “primed” physiologic phenotype. Therefore, we wanted to test whether the addition of oxLDL within Atheroprone hemodynamics (where NFkB signaling was already activated) would further enhance inflammatory signals downstream of NFkB in an endothelial cell (EC) and smooth muscle cell (SMC) co-culture. After preconditioning cells with Atheroprone shear stress, NFkB activity and gene expression is significantly increased compared to cells exposed to shear stress patterns from regions protected from atherosclerosis. Adding oxLDL to this system further enhances inflammatory gene expression in a dose-dependent fashion above Atheroprone conditions treated with native LDL (nLDL). Performing gene arrays we found that oxLDL regulated over 350 genes in ECs compared to cells treated with nLDL. These gene panels were enriched with shear stress-regulated, pro- (VCAM, E-Selectin) and anti-(KLF2, eNOS) inflammatory genes. Though not directly exposed to either Atheroprone shear stress or LDL, over 50 genes were regulated by these conditions in the underlying SMCs in our co-culture system, including inflammatory genes. Lastly, we measured changes in protein secretion due to the addition of oxLDL compared to nLDL. Many NFkB-dependent, pro-inflammatory cytokine levels were increased, including IL8, MCP-1, and IL6. Investigating the role of oxLDL within the context of physiologic shear stress was found to enhance the Atheroprone-regulated gene profile towards a more pro-inflammatory phenotype. These conditions mimic vessel wall inflammation found in human arteries and provide an ideal environment for testing drugs intended for treating advanced atherosclerosis.
- © 2012 by American Heart Association, Inc.