Abstract 20214: Lipoprotein Lipase Hydrolysis Products Differentially Regulate Gene Expression in Human THP-1 Macrophages
Introduction: Lipoprotein lipase (LPL) expression in the aorta is associated with atherosclerosis, and the free fatty acid (FFA) component of LPL hydrolysis products detrimentally affects genes associated with macrophage cholesterol efflux. However, the complete effects of LPL hydrolysis products and its FFA component on macrophage gene expression and atherosclerosis are not fully understood.
Hypothesis: The FFA liberated from lipoproteins by LPL affect gene expression in macrophages to potentially promote atherogenesis.
Methods: Total lipoproteins from fasted normolipidemic subjects were hydrolyzed with human LPL to generate LPL hydrolysis products, which were incubated with human THP-1 macrophages at 0.68 mM (by FFA content). Gene expression was compared to macrophages incubated with a non-hydrolyzed control using microarrays. We further assessed the expression of select transcripts (as identified from microarrays) by incubating THP-1 cells with either the total FFA component of the hydrolysis products, or individual classes of FFA - all matching the concentrations of individual species of FFA within LPL hydrolysis products.
Results: Our microarray data showed that LPL hydrolysis products upregulated 183 transcripts and downregulated 133 transcripts - (false discovery rate=0.03, n=3). Of the upregulated transcripts, 63 were small nucleolar RNAs. Gene ontology (GO) analyses suggest that the LPL hydrolysis product data is indicative of foam cell formation. Select transcripts identified from GO analyses associated with ribosome synthesis (SNORA56/DKC1V3), cell cycle (PCNA), stress response (ATF3), type I interferon signaling (IFITM1), and lipid metabolism (CD36 and PLIN2) were validated by qPCR (p<0.05, n=3). Analysis of the expression of these transcripts in the presence of either the total FFA component of the hydrolysis products, or individual classes of the FFA component, revealed mixed effects on the gene expression versus those observed for the LPL hydrolysis product treatment.
Conclusions: LPL hydrolysis products appear to affect the expression of genes that favor foam cell formation, but it is likely that components other than the FFA differentially affect macrophage gene expression.
Author Disclosures: N. Thyagarajan: None. S.L. Christian: None. R.J. Brown: None.
- © 2016 by American Heart Association, Inc.