Interaction of Choline and Fat in the Prenatal Programming of Nonalcoholic Steatohepatitis

Summary Nonalcoholic steatohepatitis (NASH), characterized by hepatic triglyceride accumulation and inflammation, is a growing public health problem that affects about 7% of the U.S. population. It is hypothesized that maternal obesity exerts the first metabolic hit to the fetal liver, priming it for fat accumulation and increased susceptibility to NASH, whereas a postnatal obesogenic environment imposes further hits that result in NASH. In this proposal, we will use choline, a semi-essential nutrient, to prevent the prenatal programming of NASH. Choline plays an important role in lipid metabolism, facilitating hepatic lipid export and serving as a methyl donor which modifies expression of lipid metabolic genes via an epigenetic mechanism. Prior research of our lab suggests that maternal choline supplementation (MCS) in obese mouse dams prevented excess triglyceride accumulation in the fetal liver partly by increasing the DNA methylation of the lipogenic gene Srebf1 and improved blood glucose homeostasis in early adulthood. MCS also increased the abundance of long-chain polyunsaturated fatty acids (LC-PUFAs) containing plasmalogens, a group of phospholipids that serve as sacrificial antioxidants, in the offspring. Since the NASH liver is characterized by oxidative stress and LC-PUFA deficiency, MCS may mitigate these risk factors of NASH. Interestingly, the beneficial effects of MCS was more prominent in offspring whose dams also received high-fat (HF) feeding during gestation, suggesting an interaction between choline and HF feeding. The objective of this study is to determine the interactive effect of CS with dietary fat on preventing the prenatal programming of NASH. The overarching hypothesis is that prenatal and postnatal CS would ameliorate NASH development initiated by a maternal HF, obesogenic diet; CS would synergize with LC-PUFA supplementation to further prevent the prenatal programming of NASH. In Aim 1, we will determine the effect of lifelong choline supplementation (CS) on preventing the prenatal programming of NASH by HF feeding. Offspring mice born to HF-induced obese dams will receive a HF, high-fructose Western style diet (WD) post- weaning to trigger NASH. Choline will be supplemented at different life stages to discern its effect by timing of intervention during the prenatal period (first hit), postnatal period (later hits), or both (first and later hits). We will use stable isotope tracing to discern the preferential partitioning of choline into its metabolic fates as phosphatidylcholine or betaine, thereby influencing the hepatic lipidomic profile and epigenetic regulation later in life. In Aim 2, we will determine the effect of CS and LC-PUFA co-supplementation on NASH prevention. Both mouse dams and offspring will receive a fish oil supplemented HF or WD diet as well as CS. We will compare the joint effect of fish oil and CS on NASH characteristics and lipidomic profile. This study will provide proof-of-concept evidence for the use of choline alone or in combination with LC-PUFA as a cost-effective and innocuous prophylactic agent for NASH programmed by prenatal and postnatal HF, obesogenic diet exposures.