title: Cholesterol attenuates linoleic acid-induced endothelial cell activation.
abstract: Vascular endothelial cell activation and dysfunction are critical early events in atherosclerosis. Even though very low or high levels of cholesterol can compromise cellular functions, cholesterol is a critical membrane component and may protect the vascular endothelium from oxidative stress and polyunsaturated fatty acid-mediated inflammatory responses. We have previously shown that the parent omega-6 fatty acid linoleic acid can markedly activate vascular endothelial cells. We now propose that membrane cholesterol can modify and inhibit linoleic acid-mediated endothelial cell dysfunction. To test this hypothesis, pulmonary artery endothelial cells were incubated with cholesterol (0 to 100 micromol/L) for 24 hours and then treated with 90 micromol/L of linoleic acid (18:2n-6) for 6 to 24 hours. In control cells, treatment with linoleic acid reduced intracellular glutathione levels and induced the DNA binding activity of nuclear factor-kappaB (NF-kappaB) leading to the upregulation of interleukin-6 (IL-6). In addition, the expression of endothelial nitric oxide synthase (eNOS) was altered, with linoleic acid increasing eNOS activity. In contrast, enrichment with cholesterol enhanced glutathione levels and reduced the linoleic acid-induced activation of NF-kappaBand the production of IL-6. Prior exposure to 50 micromol/L cholesterol also prevented the fatty acid-induced increase in eNOS activation. Cholesterol loading activated peroxisome proliferator-activated receptor-gamma (PPAR-gamma), a nuclear receptor that can decrease inflammatory responses. Furthermore, the PPAR-gamma agonist thiazolidinedione markedly downregulated the NF-kappaB activation mediated by linoleic acid. Our data suggest that signaling pathways linked to endothelial cell activation by prooxidant and proinflammatory insults may be influenced by cellular cholesterol levels.
authors.affiliation: Department of Animal Sciences, the Graduate Center for Nutritional Sciences, University of Kentucky, Lexington 40546-0215, USA.
authors.forename: Purushothaman
authors.initials: P
authors.lastname: Meerarani
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Smart
authors.forename: Michal
authors.initials: M
authors.lastname: Toborek
authors.forename: Gilbert A
authors.initials: GA
authors.lastname: Boissonneault
authors.forename: Bernhard
authors.initials: B
authors.lastname: Hennig
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002784:Cholesterol / Q000494:pharmacology*; D003470:Culture Media; D024202:Electrophoretic Mobility Shift Assay; D004730:Endothelium, Vascular / Q000166:cytology* / Q000187:drug effects; D005978:Glutathione / Q000378:metabolism; D007249:Inflammation / Q000473:pathology; D015850:Interleukin-6 / Q000096:biosynthesis; D019787:Linoleic Acid / Q000494:pharmacology*; D016328:NF-kappa B / Q000187:drug effects / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000096:biosynthesis / Q000235:genetics; D052250:Nitric Oxide Synthase Type III; D016877:Oxidants / Q000494:pharmacology; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013552:Swine; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D003470:Culture Media; D015850:Interleukin-6; D016328:NF-kappa B; D016877:Oxidants; D018160:Receptors, Cytoplasmic and Nuclear; D014157:Transcription Factors; D002784:Cholesterol; D019787:Linoleic Acid; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; D005978:Glutathione