Location: Arkansas Children's Nutrition CenterTitle: Increased accumulation of 4-hydroxynonenal adducts in female GSTA4/PPAR alpha double knockout mice enhance steatosis and inflammation in a model of pediatric nonalcoholic fatty liver disease Author
Submitted to: Hepatology
Publication Type: Abstract Only
Publication Acceptance Date: 9/15/2013
Publication Date: 12/15/2013
Citation: Mercer, K.E., Sharma, N.E., Shearn, C.T., Vantrease, J., Bozzola, C., Albano, E., Badger, T.M., Petersen, D.R., Ronis, M.J. 2013. Increased accumulation of 4-hydroxynonenal adducts in female GSTA4/PPAR alpha double knockout mice enhance steatosis and inflammation in a model of pediatric nonalcoholic fatty liver disease [abstract]. Hepatology. 58(S1):#716. p92A–207A. doi: 10.1002/hep.26726. Interpretive Summary:
Technical Abstract: Hepatocellular injury resulting from increased lipid peroxidation products and oxidative stress is considered a potential mechanism driving the progression of nonalcoholic fatty liver disease (NAFLD) to nonalcoholic steatohepatitsis (NASH). To test the significance of lipid peroxidation and protein adduct formation in the development of pediatric NASH, we crossed 129/SvJ gluthatione S-transferase alpha 4 (GST'4-/- )knockout mice which lack the ability to metabolize lipid peroxidation products, particularly 4-hydroxynonenal (4-HNE), with peroxisome proliferator-activated receptor-' null mice to produce a double knockout (dKO) strain. At PND21, wild type, GSTA4-/-, PPAR alpha-/- and dKO female mice were fed a 70% corn oil high fat (HF) liquid diet for 12 weeks. In response to the HF diet, we observed larger weight gains in body, liver, and visceral fat in the PPAR alpha-/- null mice compared to HF-treated dKO mice (p<0.05). However in the HF-fed dKO mice, hepatic lipid accumulation and lipid droplet size were significantly increased when compared to either the GSTA4-/- or PPAR alpha-/- fed mice. Hepatomegaly in the HF-fed dKO mice also corresponded to marked increases in 4HNE adducts and a decrease in the GSH:GSSG ratio when (p<0.05) compared to the PPAR alpha-/- null mice, suggestive of increased oxidative stress. Expression of pro-inflammatory cytokines, TNF alpha and IL-6 mRNA were up-regulated to a greater extent in the livers of HF-fed dKO mice compared to HF-fed GSTA4-/-, PPAR alpha-/- mice (p<0.05), despite no observable differences in immune cell infiltration. Development of NASH pathology occurred in both HF-fed PPAR alpha-/- and dKO mice but not in HF-fed wild type or GSTA4-/- mice. However, there were no overall changes in expression of fibrotic markers (aSMA, ColA1) or extracellular matrix remodeling (MMP9, TIMP-1, MMP13) between the HF-fed dKO and PPAR alpha-/- mice, suggesting that the PPAR alpha-/- phenotype is the predominant driver of fibrosis in this model of pediatric NAFLD. In conclusion, we developed an animal model by which HF feeding of weanling GSTA4/PPAR alpha dKO mice resulted in a pathological progression of NAFLD to NASH, supporting the role of lipid peroxidation in development of steatosis and inflammation in pediatric NAFLD.