title: Anti-atherosclerotic effects of sirolimus on human vascular smooth muscle cells.
abstract: Sirolimus is a potent immunosuppressive agent and has an anti-atherosclerotic effect through its anti-proliferative property. The present study was undertaken to investigate the effect of sirolimus on intracellular cholesterol homeostasis in human vascular smooth muscle cells (VSMCs) in the presence of inflammatory cytokine IL-1 beta. We explored the effect of sirolimus on the lipid accumulation of VSMCs in the presence of IL-1 beta, using Oil Red O staining and quantitative measurement of intracellular cholesterol. The effect of sirolimus on the gene and protein expression of lipoprotein receptors and ATP binding cassettes (ABCA1 and ABCG1) was examined by real-time PCR and Western blotting, respectively. Furthermore, the effect of sirolimus on cholesterol efflux from VSMCs in the presence or absence of IL-1 beta was also investigated using [(3)H] cholesterol efflux. Finally, we examined the effect of sirolimus on the production of inflammatory cytokines in VSMCs using ELISA. Sirolimus reduced intracellular lipid accumulation in VSMCs mediated by IL-1 beta possibly due to the reduction of expression of low-density lipoprotein (LDL) and very low-density lipoprotein (VLDL) receptors. Sirolimus increased cholesterol efflux from VSMCs and overrode the suppression of cholesterol efflux induced by IL-1 beta. Sirolimus also increased ABCA1 and ABCG1 genes expression, even in the presence of IL-1 beta. We further confirmed that sirolimus inhibited mRNA and protein expression of inflammatory cytokines IL-6, tumor necrosis factor-alpha, IL-8, and monocyte chemoattractant protein-1. Inhibition of lipid uptake together with increasing cholesterol efflux and the inhibition of inflammatory cytokines are all important aspects of the anti-atherosclerotic effects of sirolimus on VSMCs.
authors.affiliation: Centre for Nephrology, Royal Free & Univ. College Medical School, University College London, London, UK.
authors.forename: Kun L
authors.initials: KL
authors.lastname: Ma
authors.forename: Xiong Z
authors.initials: XZ
authors.lastname: Ruan
authors.forename: Stephen H
authors.initials: SH
authors.lastname: Powis
authors.forename: John F
authors.initials: JF
authors.lastname: Moorhead
authors.forename: Zac
authors.initials: Z
authors.lastname: Varghese
mesh_terms: D064286:ATP Binding Cassette Transporter 1; D000070998:ATP Binding Cassette Transporter, Subfamily G, Member 1; D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism; D050197:Atherosclerosis / Q000235:genetics / Q000378:metabolism / Q000517:prevention & control*; D001391:Azo Compounds; D002317:Cardiovascular Agents / Q000494:pharmacology* / Q000627:therapeutic use; D002478:Cells, Cultured; D002784:Cholesterol / Q000378:metabolism*; D004396:Coloring Agents; D003331:Coronary Vessels / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015870:Gene Expression / Q000187:drug effects; D006706:Homeostasis / Q000187:drug effects; D006801:Humans; D007249:Inflammation / Q000235:genetics / Q000378:metabolism / Q000517:prevention & control*; D053583:Interleukin-1beta / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000187:drug effects* / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011973:Receptors, LDL / Q000235:genetics / Q000378:metabolism; D020123:Sirolimus / Q000494:pharmacology* / Q000627:therapeutic use; D013194:Staining and Labeling / Q000379:methods
chemical_list: C577836:ABCA1 protein, human; C419353:ABCG1 protein, human; D064286:ATP Binding Cassette Transporter 1; D000070998:ATP Binding Cassette Transporter, Subfamily G, Member 1; D018528:ATP-Binding Cassette Transporters; D001391:Azo Compounds; D002317:Cardiovascular Agents; D004396:Coloring Agents; D016207:Cytokines; D053583:Interleukin-1beta; D012333:RNA, Messenger; D011973:Receptors, LDL; C036053:VLDL receptor; D002784:Cholesterol; C011049:oil red O; D020123:Sirolimus