title: Palmitate induces interleukin-8 expression in human aortic vascular smooth muscle cells via Toll-like receptor 4/nuclear factor-κB pathway (TLR4/NF-κB-8).
abstract: BACKGROUND
  Recent evidence demonstrates that saturated free fatty acids (FFAs) induce the inflammatory response via the Toll-like receptor 4 (TLR4) pathway. Interleukin-8 (IL-8) is a proinflammatory cytokine that induces vascular smooth muscle cell proliferation and migration in vitro. However, the regulation of IL-8 expression by palmitate in human vascular smooth muscle cells (HVSMCs) has not been clarified. The aim of this study was to investigate the regulation of IL-8 expression by free fatty acids and determine the underlying mechanisms in HVSMCs.
  
  
  METHODS
  Human vascular smooth muscle cells were cultured and treated with palmitate, various signaling inhibitors or TLR4 shRNA adenovirus, and the mRNA and protein expression levels of IL-8, nuclear factor κB (NF-κB) luciferase activity and NF-κB p65 binding activity were studied.
  
  
  RESULTS
  Palmitate induced IL-8 mRNA expression and secretion in a dose-dependent manner. Palmitate significantly stimulated both nuclear factor κB (NF-κB) luciferase activity and NF-κB p65 binding activity, which were markedly diminished by pretreatment with the NF-κB inhibitor, parthenolide. Parthenolide pretreatment also abolished IL-8 mRNA and protein induction by palmitate. By contrast, disrupting the ceramide and phosphoinositide-3 kinase (PI3K) pathways with myriocin and wortmannin did not affect palmitate-induced IL-8 expression. Inhibition of protein kinase C (PKC) activation with calphostin C and chelerythrine partially suppressed palmitate-stimulated IL-8 expression, but it had no effect on palmitate-induced NF-κB activation. Finally, knockdown of TLR4 markedly abolished palmitate-induced NF-κB activation and IL-8 expression.
  
  
  CONCLUSIONS
  Palmitate induces IL-8 gene expression in HVSMCs through the TLR4/NF-κB pathway.
authors.affiliation: Department of Endocrinology, Gansu Provincial Hospital, Lanzhou, China.
authors.forename: Jinxing
authors.initials: J
authors.lastname: Quan
authors.forename: Jing
authors.initials: J
authors.lastname: Liu
authors.forename: Xiaobo
authors.initials: X
authors.lastname: Gao
authors.forename: Juxiang
authors.initials: J
authors.lastname: Liu
authors.forename: Haijing
authors.initials: H
authors.lastname: Yang
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
authors.forename: Weihua
authors.initials: W
authors.lastname: Li
authors.forename: Yonghong
authors.initials: Y
authors.lastname: Li
authors.forename: Weiguo
authors.initials: W
authors.lastname: Yang
authors.forename: Baoli
authors.initials: B
authors.lastname: Wang
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D001011:Aorta / Q000166:cytology; D015153:Blotting, Western; D002478:Cells, Cultured; D002518:Ceramides / Q000378:metabolism; D004731:Endotoxins / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D016209:Interleukin-8 / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D010168:Palmitates / Q000494:pharmacology*; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects*; D051197:Toll-Like Receptor 4 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: D002518:Ceramides; D004731:Endotoxins; D016209:Interleukin-8; D016328:NF-kappa B; D010168:Palmitates; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4; D019869:Phosphatidylinositol 3-Kinases; D011493:Protein Kinase C
keywords: Toll-like receptor 4; human vascular smooth muscle cells; interleukin-8; palmitate; signaling pathway; 人主动脉血管平滑肌细胞，白细胞介素-8，软脂酸，信号通路，果蝇样受体4