title: TLR3/TRIF signalling pathway regulates IL-32 and IFN-β secretion through activation of RIP-1 and TRAF in the human cornea.
abstract: Toll-like receptor-3 (TLR3) and RNA helicase retinoic-acid-inducible protein-1 (RIG-I) serve as cytoplasmic sensors for viral RNA components. In this study, we investigated how the TLR3 and RIG-I signalling pathway was stimulated by viral infection to produce interleukin (IL)-32-mediated pro-inflammatory cytokines and type I interferon in the corneal epithelium using Epstein-Barr virus (EBV)-infected human cornea epithelial cells (HCECs/EBV) as a model of viral keratitis. Increased TLR3 and RIG-I that are responded to EBV-encoded RNA 1 and 2 (EBER1 and EBER2) induced the secretion of IL-32-mediated pro-inflammatory cytokines and IFN-β through up-regulation of TRIF/TRAF family proteins or RIP-1. TRIF silencing or TLR3 inhibitors more efficiently inhibited sequential phosphorylation of TAK1, TBK1, NF-κB and IRFs to produce pro-inflammatory cytokines and IFN-β than RIG-I-siRNA transfection in HCECs/EBV. Blockade of RIP-1, which connects the TLR3 and RIG-I pathways, significantly blocked the TLR3/TRIF-mediated and RIG-I-mediated pro-inflammatory cytokines and IFN-β production in HCECs/EBV. These findings demonstrate that TLR3/TRIF-dependent signalling pathway against viral RNA might be a main target to control inflammation and anti-viral responses in the ocular surface.
authors.affiliation: Department of Anatomy, Inje University College of Medicine, Busan, Korea; Ocular Neovascular disease Research Center, Inje University Busan Paik Hospital, Busan, Korea.
authors.forename: Ga Bin
authors.initials: GB
authors.lastname: Park
authors.forename: Dae Young
authors.initials: DY
authors.lastname: Hur
authors.forename: Yeong Seok
authors.initials: YS
authors.lastname: Kim
authors.forename: Hyun-Kyung
authors.initials: HK
authors.lastname: Lee
authors.forename: Jae Wook
authors.initials: JW
authors.lastname: Yang
authors.forename: Daejin
authors.initials: D
authors.lastname: Kim
mesh_terms: D033942:Adaptor Proteins, Vesicular Transport / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D002478:Cells, Cultured; D003315:Cornea / Q000166:cytology; D000071457:DEAD Box Protein 58; D053487:DEAD-box RNA Helicases / Q000235:genetics / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism* / Q000821:virology; D004854:Herpesvirus 4, Human / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D054884:Host-Pathogen Interactions / Q000235:genetics; D006801:Humans; D015151:Immunoblotting; D016899:Interferon-beta / Q000235:genetics* / Q000378:metabolism; D007378:Interleukins / Q000235:genetics* / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D011485:Protein Binding; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D012367:RNA, Viral / Q000235:genetics / Q000378:metabolism; D053422:Receptor-Interacting Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism; D011971:Receptors, Immunologic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000235:genetics; D048029:TNF Receptor-Associated Factor 6 / Q000235:genetics* / Q000378:metabolism; D051196:Toll-Like Receptor 3 / Q000235:genetics* / Q000378:metabolism
chemical_list: D033942:Adaptor Proteins, Vesicular Transport; C099537:Epstein-Barr virus encoded RNA 1; C106732:Epstein-Barr virus encoded RNA 2; C496971:IL32 protein, human; D007378:Interleukins; D016328:NF-kappa B; D020033:Protein Isoforms; D012367:RNA, Viral; D011971:Receptors, Immunologic; C470409:TICAM1 protein, human; C495344:TLR3 protein, human; D048029:TNF Receptor-Associated Factor 6; D051196:Toll-Like Receptor 3; D016899:Interferon-beta; C506249:RIPK1 protein, human; D053422:Receptor-Interacting Protein Serine-Threonine Kinases; C452820:RIGI protein, human; D000071457:DEAD Box Protein 58; D053487:DEAD-box RNA Helicases
keywords: Epstein-Barr virus; IL-32; RIG-I; RIP-1; TRIF; human cornea epithelial cells