Comparative Gene Expression Profiles Induced by PPARγ and PPARα/γ Agonists in Human Hepatocytes

Abstract

BackgroundSeveral glitazones (PPARγ agonists) and glitazars (dual PPARα/γ agonists) have been developed to treat hyperglycemia and, simultaneously, hyperglycemia and dyslipidemia, respectively. However, most have caused idiosyncratic hepatic or extrahepatic toxicities through mechanisms that remain largely unknown. Since the liver plays a key role in lipid metabolism, we analyzed changes in gene expression profiles induced by these two types of PPAR agonists in human hepatocytes.Methodology/Principal FindingsPrimary human hepatocytes and the well-differentiated human hepatoma HepaRG cells were exposed to different concentrations of two PPARγ (troglitazone and rosiglitazone) and two PPARα/γ (muraglitazar and tesaglitazar) agonists for 24 h and their transcriptomes were analyzed using human pangenomic Agilent microarrays. Principal Component Analysis, hierarchical clustering and Ingenuity Pathway Analysis® revealed large inter-individual variability in the response of the human hepatocyte populations to the different compounds. Many genes involved in lipid, carbohydrate, xenobiotic and cholesterol metabolism, as well as inflammation and immunity, were regulated by both PPARγ and PPARα/γ agonists in at least a number of human hepatocyte populations and/or HepaRG cells. Only a few genes were selectively deregulated by glitazars when compared to glitazones, indicating that PPARγ and PPARα/γ agonists share most of their target genes. Moreover, some target genes thought to be regulated only in mouse or to be expressed in Kupffer cells were also found to be responsive in human hepatocytes and HepaRG cells.Conclusions/SignificanceThis first comprehensive analysis of gene regulation by PPARγ and PPARα/γ agonists favor the conclusion that glitazones and glitazars share most of their target genes and induce large differential changes in gene profiles in human hepatocytes depending on hepatocyte donor, the compound class and/or individual compound, thereby supporting the occurrence of idiosyncratic toxicity in some patients.

Lipid-Induced Toxicity Stimulates Hepatocytes to Release Angiogenic Microparticles That Require Vanin-1 for Uptake by Endothelial Cells

“…This is consistent with a previous report demonstrating that cells organize themselves into tube-like structures mainly by changing their shape and establishing contacts with neighboring cells without proliferating to a substantial extent (34). In addition, the lipotoxicity-dependent increase in VNN1 abundance has been reported to depend on PPAR factors (35). In our study, the exposure of HepG2 cells to saturated and unsaturated FFAs increased the mRNA expression of PPARα and VNN1 but not that of PPAR γ (fig.…”

PPAR agonists regulate brain gene expression: Relationship to their effects on ethanol consumption

“…The amygdala and PFC were chosen for their importance in reward signaling and ethanol dependence 25 . The liver was chosen in order to validate microarray results since PPAR agonists are known to change liver gene expression 47 .…”

Transcriptomic analysis of untreated and drug-treated differentiated HepaRG cells over a 2-week period

“…the results were used as references ous reports with the same PPAR agonists.After daily treatments for 14 days lipid and drug metabolisms 409 remained the two main deregulated pathways, as previously410 observed after a short term exposure(Rogue et al, 2011). However,411 both qualitative and quantitative changes in gene profiling were 412 associated with repeated treatments.…”

“…Nevertheless,70 there is presently at least one exception represented by the 71 HepaRG cell line that can differentiate from a bipotent progenitor 72 state to attain features of normal adult hepatocytes in primary cul-73 ture without losing the indefinite growth property of immortalized 74 cell lines (Cerec et al, 2007;Guillouzo et al, 2007). 75 HepaRG cells have been shown to be a suitable in vitro cell 76 model for studies on viral B infection and replication (Gripon 77 et al, 2002) and xenobiotic metabolism and toxicity (Aninat 78 et al, 2006;Antherieu et al, 2010 (Lambert et al, 2009;Rogue et al, 2011Rogue et al, , 2012. 84 Contrary to other liver cell lines which continue to grow and 85 consequently do not remain functionally stable, HepaRG cells cease 86 to proliferate at confluence.…”