Abstract 190: Classic Lipid and Novel Inflammatory Phenotypes in an Induced Pluripotent Stem Cell--Derived Macrophage Model of Tangier Disease
Tangier disease (TD) is an autosomal recessive disorder caused by mutations in the ATP-binding cassette transporter A1 (ABCA1). These result in a greatly reduced ability to transport cholesterol out of cells, leading to the accumulation of cholesterol in macrophages and many other body tissues expressing ABCA1. We recruited two TD individuals, TD1, compound heterozygote at S2046R/K531N, and TD2, homozygous for the E1005X/E1005X truncation mutation, as well as heterozygote/non-affected family members, and healthy controls. We reprogrammed PBMC of TD patients and controls to pluripotency by Sendai viral transduction with Oct3/4, Sox2, Klf4 and c-Myc. TD-iPSC expressed pluripotency markers including SSEA-3, SSEA-4, TRA-1.60, and TRA-1.81, and maintained a normal karyotype. TD iPSC differentiated efficiently to macrophages. iPSC-derived macrophages (IPSDM) characteristics paralleled those of primary PBMC-derived macrophages (HMDM) at morphological, phenotypic and transcriptomic levels. TD-IPSDM and HMDM showed no cholesterol efflux to apolipoprotein A-I (apoA-I) and impaired efflux to HDL3. Treatment of TD cells with LXR agonists, which upregulate ABCA1 expression, failed to enhance cholesterol efflux to apoA-I in TD-IPSDM and HMDM consistent with the absence of functional ABCA1. In both IPSDM and HMDM, the heterozygote ABCA1 mutation carrier had an intermediate defect in cholesterol efflux and a partial response to the LXR agonist consistent with the presence of one functional allele. Relative to control-IPSDM, TD-IPSDM also showed a higher cholesterol ester/total cholesterol (CE/TC) ratio upon acetylated-LDL loading. Compared with control-IPSDM, TD-IPSDM showed enhanced phagocytosis of zymosan particles and greater inflammatory response to ATP treatment in lipopolysaccharide (LPS)-primed IPSDM, evidenced by markedly elevated gene expression of IL-1beta, IL-6, IL-8 and CCL5, but not TNF-alpha. These observations provide further support for the utility of IPSDM in defining more subtle macrophage phenotypes that are less obvious manifestations of Mendelian disorders. We conclude that macrophages derived from TD IPS can effectively recapitulate pathologic hallmarks of the disease.
Author Disclosures: H. Zhang: None. R. Shah: None. K. Bermingham: None. C. Hinkle: None. A. Rodrigues: None. M. Cuchel: None. Y. Liu: None. W. Yang: None. D. VanDorn: None. S. Chou: None. E.E. Morrisey: None. D.J. Rader: None. M.P. Reilly: None.
- © 2014 by American Heart Association, Inc.