Molecular markers of brain cholesterol homeostasis are unchanged despite a smaller brain mass in a mouse model of cholesteryl ester storage disease

Abstract

Lysosomal acid lipase (LAL), encoded by the gene LIPA, facilitates the intracellular processing of lipids by hydrolyzing cholesteryl esters and triacylglycerols present in newly internalized lipoproteins. Loss-of-function mutations in LIPA result in cholesteryl ester storage disease (CESD) or Wolman disease when mutations cause complete loss of LAL activity. Although the phenotype of a mouse CESD model has been extensively characterized, there has not been a focus on the brain at different stages of disease progression. In the current studies, whole-brain mass and the concentrations of cholesterol in both the esterified (EC) and unesterified (UC) fractions were measured in Lal^−/− and matching Lal^+/+ mice (FVB-N strain) at ages ranging from 14 up to 280 days after birth. Compared to Lal^+/+controls at 50, 68–76, 140–142, and 230–280 days of age, Lal^−/− mice had brain weights that averaged approximately 6%, 7%, 18%, and 20% less, respectively. Brain EC levels were higher in the Lal^−/− mice at every age, being elevated 27-fold at 230–280 days. Brain UC concentrations did not show a genotypic difference at any age. The elevated brain EC levels in the Lal^−/− mice did not reflect EC in residual blood. An mRNA expression analysis for an array of genes involved in the synthesis, catabolism, storage, and transport of cholesterol in the brains of 141-day old mice did not detect any genotypic differences although the relative mRNA levels for several markers of inflammation were moderately elevated in the Lal^−/− mice. The possible sites of EC accretion in the central nervous system are discussed.