title: Inhibition of TLR3-mediated proinflammatory effects by Alkylphosphocholines in human retinal pigment epithelial cells.
abstract: PURPOSE. To elucidate the role of Toll-like receptor 3 (TLR3) in the pathogenesis of age-related macular degeneration (AMD) and to investigate the effect of alkylphosphocholines (APCs) on the TLR3-mediated expression of cytokines and growth factors in human retinal pigment epithelial (RPE) cells. METHODS. Confluent cultures of human RPE cells (ARPE-19) were stimulated with poly (I:C) RNA as a well-established ligand for TLR3. Cytokine profiles were determined by RT-PCR on the activation of TLR3. RPE cells were transfected with siRNA specific for TLR3 and RIG-1 to determine the receptors involved. The effect of preincubation of RPE cells with APCs on the expression level of target genes was assessed. RESULTS. Poly (I:C) RNA stimulation led to a dose-dependent increase in the expression of TLR3 and RIG-I. A significant increase in expression levels of IL-6, TNF-α, IL-8, MCP-1, ICAM-1, and BFGF was observed after poly (I:C) RNA stimulation (P < 0.05). This effect was time and dose dependent. No effect on PEDG or VEGF expression was seen. Transfection of RPE cells with siRNA specific for TLR3 reduced poly (I:C) RNA-induced mRNA expression of the genes (P < 0.05). Preincubation of RPE cells with APCs significantly reduced the poly (I:C) RNA-induced expression of the target genes (P < 0.05). CONCLUSIONS. The authors demonstrate that the expression of proinflammatory cytokines and chemokines in RPE cells depends on the activation of TLR3. The induction of downstream gene expression is blocked by siRNA specific for TLR3 and alkylphosphocholines. Therefore, TLR3 should be considered a novel target in AMD therapy.
authors.affiliation: Ludwig-Maximilians-University, Medical Policlinic, Department of Internal Medicine, Klinikum der Universita¨t Mu¨nchen, Campus Innenstadt, Munich, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Wörnle
authors.forename: Monika
authors.initials: M
authors.lastname: Merkle
authors.forename: Armin
authors.initials: A
authors.lastname: Wolf
authors.forename: Andrea
authors.initials: A
authors.lastname: Ribeiro
authors.forename: Susanne
authors.initials: S
authors.lastname: Himmelein
authors.forename: Marcus
authors.initials: M
authors.lastname: Kernt
authors.forename: Anselm
authors.initials: A
authors.lastname: Kampik
authors.forename: Kirsten H
authors.initials: KH
authors.lastname: Eibl-Lindner
mesh_terms: D017209:Apoptosis; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism; D000071457:DEAD Box Protein 58; D053487:DEAD-box RNA Helicases / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005136:Eye Proteins / Q000235:genetics; D016222:Fibroblast Growth Factor 2 / Q000235:genetics; D055785:Gene Knockdown Techniques; D020868:Gene Silencing / Q000187:drug effects*; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism*; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics; D009414:Nerve Growth Factors / Q000235:genetics; D010767:Phosphorylcholine / Q000494:pharmacology*; D011070:Poly I-C / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D011971:Receptors, Immunologic; D055213:Retinal Pigment Epithelium / Q000187:drug effects* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015843:Serpins / Q000235:genetics; D013997:Time Factors; D051196:Toll-Like Receptor 3 / Q000235:genetics* / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics; D000099174:Pigment Epithelium-Derived Factor
chemical_list: D016207:Cytokines; D000071457:DEAD Box Protein 58; D053487:DEAD-box RNA Helicases; D005136:Eye Proteins; D016222:Fibroblast Growth Factor 2; D018836:Inflammation Mediators; D018799:Intercellular Adhesion Molecule-1; D009414:Nerve Growth Factors; D010767:Phosphorylcholine; D011070:Poly I-C; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D011971:Receptors, Immunologic; D015843:Serpins; D051196:Toll-Like Receptor 3; D042461:Vascular Endothelial Growth Factor A; D000099174:Pigment Epithelium-Derived Factor; C495344:TLR3 protein, human; C467484:VEGFA protein, human; C452820:RIGI protein, human