Enzyme-modified non-oxidized LDL (ELDL) induces human coronary artery smooth muscle cell transformation to a migratory and osteoblast-like phenotype

Abstract

Enzyme modified non-oxidative LDL (ELDL) is effectively taken up by vascular smooth muscle cells (SMC) and mediates transition into foam cells and produces phenotypic changes in SMC function. Our data show that incubation of human coronary artery SMC (HCASMC) with low concentration of ELDL (10 μg/ml) results in significantly enhanced foam cell formation compared to oxidized LDL (200 μg/ml; p < 0.01) or native LDL (200 μg/ml; p < 0.01). Bioinformatic network analysis identified activation of p38 MAPK, NFkB, ERK as top canonical pathways relevant for biological processes linked to cell migration and osteoblastic differentiation in ELDL-treated cells. Functional studies confirmed increased migration of HCASMC upon stimulation with ELDL (10 μg/ml) or Angiopoietin like protein 4, (ANGPTL4, 5 μg/ml), and gain in osteoblastic gene profile with significant increase in mRNA levels for DMP-1, ALPL, RUNX2, OPN/SPP1, osterix/SP7, BMP and reduction in mRNA for MGP and ENPP1. Enhanced calcification of HCASMC by ELDL was demonstrated by Alizarin Red staining. In summary, ELDL is highly potent in inducing foam cells in HCASMC and mediates a phenotypic switch with enhanced migration and osteoblastic gene profile. These results point to the potential of ELDL to induce migratory and osteoblastic effects in human smooth muscle cells with potential implications for migration and calcification of SMCs in human atherosclerosis.

S100/RAGE-Mediated Inflammation and Modified Cholesterol Lipoproteins as Mediators of Osteoblastic Differentiation of Vascular Smooth Muscle Cells

“…This is in contrast to macrophages, which readily take up oxidized LDL, acetylated LDL, ELDL, and native LDL (Figure 3 ). We demonstrated that ELDL uptake by SMC is dependent on macropinocytosis, rather than on scavenger receptors ( 61 , 62 ). Macropinocytosis is the process whereby the cell membrane folds to form vacuoles and thereby incorporates bulk cargo, such as dissolved molecules, and large volumes of extracellular fluid.…”

“…In vivo , ELDL represents one of the many forms of modified LDLs that form foam cells in macrophages and smooth muscles cells, and phenotypic modulations brought about by individual modified LDLs overlap significantly in an atherosclerotic milieu, making it practically impossible to differentiate between each other. By studying in vitro -generated modifications of LDL we were able to demonstrate marked differences in the transcriptome of HCASMCs upon uptake of ELDL, OxLDL, and native LDL, indicating that specific modifications of LDL in the atherosclerotic plaques may determine the biology and functional consequences in vasculature ( 62 ). A main finding was that gene expression is distinctly different between HCASMC stimulated with oxidized LDL compared to ELDL or native LDL.…”

Role of Phagocytosis in the Pro-Inflammatory Response in LDL-Induced Foam Cell Formation; a Transcriptome Analysis

“…Thus, modified LDL caused the gene regulation characteristic of the stimulation of phagocytosis. The current results can be compared to data on the effects of enzyme-modified non-oxidized LDL (ELDL) on vascular smooth muscle cells obtained by a different research group [43]. Their study demonstrated that ELDL could induce a phenotypic switch of the smooth muscle cells, accordingly, changing the expression of certain regulatory genes and inducing foam cell formation.…”

Bavachin Protects Human Aortic Smooth Muscle Cells Against β-Glycerophosphate-Mediated Vascular Calcification and Apoptosis via Activation of mTOR-Dependent Autophagy and Suppression of β-Catenin Signaling

“…Furthermore, addition of autophagy inhibitor, wortmannin (WM) attenuated the inhibitory effect of bavachin on β-GP-induced calcification and apoptosis in HASMCs. Collectively, the present study revealed that bavachin protects HASMCs against apoptosis and calcification by activation of the Atg7/ inTRODUCTiOn Vascular calcification (VC) is the pathogenic process of accumulating the crystals of calcium phosphate with in the blood vessel (Hofmann Bowman and McNally, 2012;Sun et al, 2012;Yahagi et al, 2017;Chellan et al, 2018;Benjamin et al, 2019). VC has been recognized as a marker of atherosclerotic plaques, which involves a complex pathological process, and has very high morbidity and mortality (Thompson and Towler, 2012;Asmat et al, 2016;Kay et al, 2016).…”