Epigenetic Mechanisms in Developmental Programming of Hepatic Lipid Dysfunction by Maternal Hypercholesterolemia

Project Summary/Abstract: Maternal hypercholesterolemia (MHC) is a pathological condition of exaggerated maternal serum cholesterol during gestation. Although there is a normal rise in maternal cholesterol during pregnancy which is vital for early organ development, an excessive increase can manifest in women with

elevated cholesterol prior to conception. Further, pregnancy conditions such as maternal obesity, gestational diabetes, and preeclampsia are associated with overt hypercholesterolemia. MHC is associated with adverse pregnancy outcomes (i.e., pre-term delivery and low birth weight) and a range of metabolic complications in offspring including increased adiposity, fetal fatty streaks that develop

faster in childhood, and the programming of non-alcoholic fatty liver disease (NAFLD). Alarmingly, as the use of lipid-lowering medication in MHC is contraindicated due to fears around fetal toxicity, there are limited acceptable treatment options and an acknowledged increase in disease risk for offspring from hyper-

cholesterolemic mothers before they are even born. This proposal addresses two critical knowledge gaps for MHC: (i) the scarcity of information on how excessive early cholesterol exposure impacts the offspring’s hepatic epigenome and how these modifications may influence NAFLD progression; and (ii) an alarming lack of cholesterol-lowering treatment options for use

during MHC. As safe and effective plant-based cholesterol-lowering agents, phytosterols (PS) and their saturated derivatives, phytostanols (PSA) are highly suitable candidates. Using a diet-induced hypercholesterolemic C57BL/6J mouse model, this proposal seeks to identify the hepatic epigenomic adaptations to excessive early-life cholesterol exposure and the influence of

maternal cholesterol-lowering strategies on the molecular and metabolic features of NAFLD in offspring. Employing methylated DNA immunoprecipitation sequencing, these studies will examine how MHC throughout pregnancy alters the DNA methylation pattern of hepatic lipid-regulatory genes in early life and

determine the persistence of these molecular adaptations into adulthood. Further, we will directly compare the efficacy of maternal PS versus PSA intervention as strategies to limit fetal exposure to excessive cholesterol and protect against the programming of NAFLD in offspring. This proposal addresses the critical question of how to make pregnancies safer for

hypercholesterolemic mothers and their children. The novel ideas presented in this proposal directly reflect the research priorities of the National Institute of Child Health and Human Development (NICHD) with particular respect to the Pediatric Growth and Nutrition Branch that seeks to ‘understand the mechanisms of growth

and development at the gene-molecular level’ and ‘identify the molecular drivers that transmit the memory of adverse intrauterine environments into adolescence and adulthood’.