High Fructose - High-Fat Diet Accelerates Non-Alcoholic Fatty Liver Disease Possibly Mitigating Hepatic Nuclear Lipocalin Prostaglandin D2Synthase

Abstract ID 98267 Poster Board 557 Nonalcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease worldwide over the last decade with no FDA-approved treatment available yet. NAFLD is a spectrum of disorders ranging from non-alcoholic fatty liver disease (NAFLD) to non-alcoholic steatohepatitis (NASH), with or without fibrosis/cirrhosis. The prevalence and rising threat of end-stage liver disease in obese and diabetic populations has garnered serious attention in the field. To prevent the worsening of this progression, it is important to discover novel therapeutic targets. Our in-vivo study showed severe fatty liver disease in lipocalin prostaglandin D2 synthase (L-PGDS) knockout mice kept on high-fat diet. Briefly, L-PGDS functions as a prostaglandin synthase where it catalyzes the isomerization of PGH2 to PGD2. PGD2 regulates its physiological function via two individual G-protein coupled receptors named DP1 and DP2. This exciting finding prompted us to investigate the role of L-PGDS in fatty liver disease via dietary manipulation where male and female C57BL/6 mice were fed either fructose or high-fat diet alone or a combination of both for 22 weeks. Our histological and biochemical results clearly showed significant hepatosteatosis in fructose as well as high-fat combination diet groups in both male and female mice. Most exciting, the mice fed a high-fat diet showed significantly decreased nuclear L-PGDS protein expression while sterol-regulatory element binding protein-1 (SREBP1), gene involved in fatty acid biosynthesis, expression significantly increased suggesting a strong interplay of L-PGDS and NAFLD. Similarly, fructose-fed group also showed similar results with reduced L-PGDS expression. Therefore, to understand the detailed mechanism, we aimed to investigate the differential regulation of L-PGDS in presence of fructose and palmitic acid using HepG2 cells. HepG2 cell line is an appropriate in-vitro model to study gluconeogenic, hepatokine, and lipogenic gene-expression pattern similar to the one observed in in-vivo settings. Briefly based on our preliminary results, HepG2 cells will be cultured with different concentrations of fructose (5.5, 10, 25, 50 and 100mM) with or without palmitic acid 250uM concentration for 24, 48, 72 and 96 hrs. Change in hepatic lipid accumulation will be the experimental outcome which will determined including Oil Red O staining, cell lysate and supernatant triglyceride measurement. Further, fructose and palmitic acid treated cell lysates will be subjected to determine subcellular changes in L-PGDS along with lipogenesis and lipolysis related proteins and mRNA expressions. Obtained results will be recapitulated in our established L-PGDS silenced HepG2 cells. Once we fully understand the regulation of L-PGDS in fatty liver disease, further studies will be carried out using appropriate mice model in the future. In summary, understanding the regulation of L-PGDS under the influence of dietary manipulation will possibly bring a potential future therapeutic target of fatty liver disease. This research is supported by Seed Grant Internal Research funding award from the St. John's University, New York.