Abstract 121: Pro-inflammatory Cytokine Ifng Modulates Hepatic Sortilin Expression and Lipid Metabolism.
Rationale: Hypercholesterolemia and immunity are two major risk factors for cardiovascular diseases (CVDs). Yet, we reported increased atherosclerosis upon depletion of regulatory T lymphocytes (Tregs). The effect was associated with increased hepatic inflammation and reduction of Sortilin expression and lipid uptake in the liver.
Objective: To define how inflammatory milieu in the liver can modulate Sortilin and lipid metabolism.
Methods: To reproduce the inflammatory milieu, hepatocytes (AML-12) were treated in vitro with IFNg. Expression of genes and proteins of interest were followed by qPCR and western blot. In silico method was used to find binding sites of signal transducer and activator of transcription (STAT1) on Sortilin, confirmed later by chromatin immune precipitation assays (Chip). Lipid uptake by hepatocytes was assessed via incubation of cells with radioactive lipoproteins.
Results: Culture of AML-12 cells with IFNg induced the phosphorylation of STAT1 showing an active signaling pathway. In the same inflammatory conditions, Sort1 mRNA is decreased meanwhile its inhibitor (Atf3) expression is increased. Kinetic experiments revealed the reduction of Sortilin after 12 hours of culture, suggesting a post-transcriptional regulation of Sort1 by STAT1.
In silico analysis revealed putative binding sites for STAT1 on Sortilin gene which was confirmed by chromatin immunoprecipitation assay (Chip).
IFNg treated hepatocytes that were incubated with radioactive lipoproteins demonstrated a reduced uptake capacity of VLDL and LDL particles compared to control cultures.
Conclusion: All together, these results suggest that inflammation through production of IFNg is able to directly modulate the lipid metabolism in hepatocytes by acting on Sortilin expression.
Author Disclosures: J. Pirault: None. K. Polyzos: None. D.F.J. Ketelhuth: None. G.K. Hansson: None.
- © 2015 by American Heart Association, Inc.