Perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), and perfluorononanoic acid (PFNA) increase triglyceride levels and decrease cholesterogenic gene expression in human HepaRG liver cells

Abstract

Per-and polyfluoroalkyl substances (PFASs) are omnipresent in the environment, food chain, and humans. Epidemiological studies have shown a positive association between serum levels of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), and increased serum cholesterol and, in some cases, also triglyceride levels. However, causality has been questioned, as animal studies, as well as a human trial, showed a decrease in serum cholesterol and no effects or a decrease in plasma triglycerides. To obtain more insight into the effects of PFASs on these processes, the present study investigated the effects of PFOA, PFOS, and perfluorononanoic acid (PFNA) on intracellular triglyceride and cholesterol levels in human HepaRG liver cells. DNA microarray analyses were performed to provide insight into underlying mechanisms. All PFASs induced an increase in cellular triglyceride levels, but had no effect on cholesterol levels. Gene set enrichment analysis (GSEA) of the microarray data indicated that gene sets related to cholesterol biosynthesis were repressed by PFOA, PFOS, and PFNA. Other gene sets commonly affected by all PFAS were related to PERK/ATF4 signaling (induced), tRNA aminoacylation (induced), amino acid transport (induced), and glycolysis/gluconeogenesis (repressed). Moreover, numerous target genes of peroxisome proliferator-activated receptor α (PPARα) were found to be upregulated. Altogether, the present study shows that PFOA, PFOS, and PFNA increase triglyceride levels and inhibit cholesterogenic gene expression in HepaRG cells. In addition, the present study indicates that PFASs induce endoplasmic reticulum stress, which may be an important mechanism underlying some of the toxic effects of these chemicals.

Systemic PFOS and PFOA exposure and disturbed lipid homeostasis in humans: what do we know and what not?

“…The activation of the hPPARa by PFOA, but also PFOS, was likewise seen with in vitro assays performed in human liver cells, such as human primary hepatocytes, or human liver cell lines (HepG2 and HepaRG) (Bjork et al 2011;Beggs et al 2016;Louisse et al 2020). These studies support the activation of PPARa signaling, at concentrations commonly ranging from 10 mM to 100 mM (PFOA: $4000-40 000 ng/mL, PFOS: $5000-50 000 ng/mL).…”

High-throughput transcriptomic analysis of human primary hepatocyte spheroids exposed to per- and polyfluoroalkyl substances (PFAS) as a platform for relative potency characterization

“…Although data for most PFAS are limited, exposure in rodents to PFOS and PFOA clearly illustrate changes in fatty acid production, cholesterol synthesis, and lipid homeostasis leading to cholestasis/steatosis (Das et al, 2017;L. Wang et al, 2014;Bijland et al, 2011;Du et al, 2009;Peden-Adams et al, 2009;Wan et al, 2012) (Curran et al, 2008;Louisse et al, 2020). In keeping with these effects, obese participants from the National Health and Nutrition Examination Survey (2011-2014) exhibit a positive association of PFOA, PFHxS and PFNA with major liver biomarkers associated with steatosis (Jain and Ducatman, 2019).…”

“…Using NHANES data, increased PFAS exposure was associated with alterations in select liver biomarkers, suggesting they play a role in the progression of non-alcoholic fatty liver disease (Jain and Ducatman, 2019). Both in vitro and in vivo studies suggest that the mechanism by which these compounds act involves increased intracellular triglycerides levels and activation of nuclear receptors (Louisse et al . 2020, Schlezinger et al, 2020).…”

Endocrine Disruptor Potential of Short- and Long-Chain Perfluoroalkyl Substances (PFASs)—A Synthesis of Current Knowledge with Proposal of Molecular Mechanism

“…It should be underlined that the concentrations of PFOA analyzed in this study were much higher than those determined in general population exposure. Data published in 2020 [ 164 ] revealed that PFOA, PFOS and PFNA increased triglyceride levels and inhibited cholesterogenic gene expression in HepaRG cells.…”