title: Effect of berberine on proinflammatory cytokine production by ARPE-19 cells following stimulation with tumor necrosis factor-α.
abstract: OBJECTIVE
  Berberine (BBR) is a well-known drug used in traditional medicine and has been shown to possess anti-inflammatory properties. Whether it can affect the production of inflammatory cytokines by RPE cells is not yet clear and was therefore the subject of our study.
  
  
  METHODS
  ARPE-19 cells were cultured with TNF-α in the presence or absence of BBR to different time points. Concentrations of IL-6, IL-8, and monocyte chemoattractant protein-1 (MCP-1) in the supernatant were measured by using an ELISA. The mRNA expression of these cytokines was measured by real-time PCR. Phosphorylation of p38 mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinase (ERK1/2), and c-Jun N-terminal kinase (JNK) was measured by Western blot assay. The signal transduction mechanisms involved in cytokine production were evaluated using various inhibitors for p38, ERK1/2, and JNK.
  
  
  RESULTS
  TNF-α significantly increased the expression of IL-6, IL-8, and MCP-1 in ARPE-19 cells at both the protein and mRNA levels. It promoted the phosphorylation of p38, ERK1/2, and JNK. Inhibitory experiments showed that IL-6 was modulated by p38, whereas IL-8 and MCP-1 were modulated by p38, ERK1/2, and JNK signal pathways. BBR inhibited the expression of IL-6, IL-8, and MCP-1 remarkably at both protein and mRNA levels and down-regulated the phosphorylation of p38, ERK1/2, and JNK upon stimulation with TNF-α.
  
  
  CONCLUSIONS
  The present results suggested that BBR significantly inhibits the expression of inflammatory cytokines in ARPE-19 cells and that the inhibitory effect is mediated by down-regulation of the p38, ERK1/2, and JNK pathways.
authors.affiliation: the    First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Ophthalmology, Chongqing Eye Institute, Chongqing, People's Republic of China; Second Affiliated Hospital of Chongqing Medical University, Chongqing, People's Republic of China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Wang
authors.forename: Jian
authors.initials: J
authors.lastname: Qi
authors.forename: Ranran
authors.initials: R
authors.lastname: Hu
authors.forename: Ying
authors.initials: Y
authors.lastname: Chen
authors.forename: Aize
authors.initials: A
authors.lastname: Kijlstra
authors.forename: Peizeng
authors.initials: P
authors.lastname: Yang
mesh_terms: D001599:Berberine / Q000494:pharmacology*; D015153:Blotting, Western; D018932:Chemokine CCL2 / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism*; D016209:Interleukin-8 / Q000378:metabolism*; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D010766:Phosphorylation; D012333:RNA, Messenger / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D055213:Retinal Pigment Epithelium / Q000187:drug effects / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D018932:Chemokine CCL2; D015850:Interleukin-6; D016209:Interleukin-8; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D001599:Berberine; D048049:Extracellular Signal-Regulated MAP Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases