title: HDL inhibits the effects of oxidized phospholipids on endothelial cell gene expression via multiple mechanisms.
abstract: Oxidized 1-palmitoyl-2-arachidonyl-sn-glycero-3-phospholcholine (OxPAPC) and its component phospholipids accumulate in atherosclerotic lesions and regulate the expression of >1,000 genes, many proatherogenic, in human aortic endothelial cells (HAECs). In contrast, there is evidence in the literature that HDL protects the vasculature from inflammatory insult. We have previously shown that in HAECs, HDL attenuates the expression of several proatherogenic genes regulated by OxPAPC and 1-palmitoyl-2-(5,6-epoxyisoprostane E2)-sn-glycero-3-phosphocholine. We now demonstrate that HDL reverses >50% of the OxPAPC transcriptional response. Genes reversed by HDL are enriched for inflammatory and vascular development pathways, while genes not affected by HDL are enriched for oxidative stress response pathways. The protective effect of HDL is partially mimicked by cholesterol repletion and treatment with apoA1 but does not require signaling through scavenger receptor class B type I. Furthermore, our data demonstrate that HDL protection requires direct interaction with OxPAPC. HDL-associated platelet-activating factor acetylhydrolase (PAF-AH) hydrolyzes short-chain bioactive phospholipids in OxPAPC; however, inhibiting PAF-AH activity does not prevent HDL protection. Our results are consistent with HDL sequestering specific bioactive lipids in OxPAPC, thereby preventing their regulation of select target genes. Overall, this work implicates HDL as a major regulator of OxPAPC action in endothelial cells via multiple mechanisms.
authors.affiliation: Department of Medicine, Division of Cardiology University of California, Los Angeles, Los Angeles, CA 90095.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Emert
authors.affiliation: Department of Medicine, Division of Cardiology University of California, Los Angeles, Los Angeles, CA 90095.
authors.forename: Yehudit
authors.initials: Y
authors.lastname: Hasin-Brumshtein
authors.affiliation: Department of Chemical Engineering, Western Michigan University, Kalamazoo, MI 49008.
authors.forename: James R
authors.initials: JR
authors.lastname: Springstead
authors.affiliation: Department of Medicine, Division of Cardiology University of California, Los Angeles, Los Angeles, CA 90095.
authors.forename: Ladan
authors.initials: L
authors.lastname: Vakili
authors.affiliation: Department of Medicine, Division of Cardiology University of California, Los Angeles, Los Angeles, CA 90095 Departments of Pathology, University of California, Los Angeles, Los Angeles, CA 90095.
authors.forename: Judith A
authors.initials: JA
authors.lastname: Berliner
authors.affiliation: Department of Medicine, Division of Cardiology University of California, Los Angeles, Los Angeles, CA 90095 Departments of Pathology, University of California, Los Angeles, Los Angeles, CA 90095 Human Genetics University of California, Los Angeles, Los Angeles, CA 90095 Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095.
authors.forename: Aldons J
authors.initials: AJ
authors.lastname: Lusis
mesh_terms: D002478:Cells, Cultured; D042783:Endothelial Cells / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D008075:Lipoproteins, HDL / Q000378:metabolism / Q000494:pharmacology*; D010743:Phospholipids / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D008075:Lipoproteins, HDL; D010743:Phospholipids
keywords: high density lipoprotein; inflammatory signaling; minimally modified low density lipoprotein; platelet-activating factor acetylhydrolase; scavenger receptor class B type I