4-Phenylbutyric acid regulates CCl4-induced acute hepatic dyslipidemia in a mouse model: A mechanism-based PK/PD study

Endoplasmic reticulum (ER) stress and associated protein aggregation are closely associated with human diseases, including alterations in hepatic lipid metabolism. Inhibition of ER stress can have a significant effect on the prevention of hepatic dyslipidemia. Here, we studied the role of 4-phenylbutyric acid (4-PBA), a chemical chaperone, on ER stress-induced hepatic lipid accumulation. We studied ER stress induction following CCl4 exposure and delineated mechanisms of the CCl4-induced ER stress response in liver tissue from mice. CCl4 affected the formation of disulfide bonds through excessive hyper-oxidation of protein disulfide isomerase (PDI). Increased complex formation between PDI and its client proteins persisted in CCl4-exposed samples. Conversely, 4-PBA inhibited ER stress via secretion of apolipoprotein B and prevention of hepatic lipid accumulation. We also studied the mechanism-based pharmacokinetic and pharmacodynamic profiles and identified the ER stress-related proteins GRP78 and CHOP, along with plasma apolipoprotein B and triglyceride levels, as novel biomarkers of ER stress-induced hepatic lipid accumulation. ER stress and its clinical relevance for therapeutic approaches were well correlated with the activity of the ER stress regulator 4-PBA, which may be a promising drug candidate for the treatment of hepatic lipid accumulation, such as hepatic steatosis.