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Macrophage-derived foam cells (FC) play a key role in atherosclerotic lesion progression. Effects of different drugs used in drug-eluting stents (DES) on FC behavior have not been well characterized. We used an in vitro model to compare effects of paclitaxel, everolimus, and tacrolimus on FC, human coronary endothelial cell (HCAEC), and human coronary smooth muscle cell (HCASMC) viability, FC gene expression, and FC inflammatory cytokine levels.
FC were derived from human THP1 macrophages with acetylated LDL, followed by treatment with paclitaxel, everolimus, or tacrolimus (10-5-10-11M) for 24 hrs (n=4). HCAEC and HCASMC were similarly treated with all three drugs. Cell lysates and media supernatants were analyzed for apoptosis/necrosis using a Cell Death Detection ELISAPLUS (Roche, Pleasanton, CA) assay. FC lysates were also evaluated for apoptosis (survivin, clusterin) and autophagy (MAP1LC3) gene expression via a Quantigene® Plex assay (Affymetrix, Santa Clara, CA). FC supernatants were analyzed for MCP1 levels via a Procarta® mmunoassay (Affymetrix). Statistical significance was set at p<0.05 by ANOVA/Holm's t-test.
FC apoptosis was significantly increased compared to control at 10-5M for both everolimus and paclitaxel, with no effects on FC necrosis for both drugs. Tacrolimus did not affect FC apoptosis or necrosis. Paclitaxel (10-5M) significantly increased clusterin and decreased survivin expression in FC. Tacrolimus did not affect gene expression while everolimus (10-5M) significantly increased MAP1LC3 and clusterin (p=0.10) and decreased survivin expression in FC. Everolimus (10-5M) significantly decreased MCP1 in FC supernatants. Effects of all three drugs on HCASMC and HCAEC viability were also explored. While everolimus and tacrolimus did not affect apoptosis or necrosis, paclitaxel (10-5M) significantly increased HCASMC and HCAEC apoptosis and necrosis.
The three drugs explored in this study have variable effects on FC, HCASMC, and HCAEC. Unlike paclitaxel and tacrolimus, everolimus may inhibit FC accumulation in atheromas through selective autophagy/apoptosis of FC and inhibition of monocyte recruitment into the arterial wall.
- 2013 American College of Cardiology Foundation