title: Bacterial LPS up-regulated TLR3 expression is critical for antiviral response in human monocytes: evidence for negative regulation by CYLD.
abstract: In the host immune system, the leukocytes are often exposed to multiple pathogens including bacteria and viruses. The principal challenge for the host is to efficiently detect the invading pathogen and mount a rapid defensive response. Leukocytes recognize invading pathogens by directly interacting with pathogen-associated molecular patterns via Toll-like receptors (TLRs) expressed on the leukocyte surfaces. In this study, we provide direct evidence that bacterial LPS enhances the host antiviral response by up-regulating TLR3 expression in human peripheral blood monocytes and monocytic cell lines, THP1 cells. Moreover, LPS induces TLR3 expression via a TLR4-MyD88-IRAK-TRAF6-NF-κB-dependent signaling pathway. Interestingly, CYLD, an important deubiquitinase, acts as a negative regulator of TLR3 induction by LPS. Our study thus provides new insights into a novel role for bacterial infection in enhancing host antiviral response; furthermore, it identifies CYLD for the first time as a critical negative regulator of bacterial LPS-induced response.
authors.affiliation: Department of Medical Microbiology and Immunology and Medicine, University of Toledo Medical Center, Toledo, OH 43614, USA.
authors.forename: Zhixing K
authors.initials: ZK
authors.lastname: Pan
authors.forename: Chris
authors.initials: C
authors.lastname: Fisher
authors.forename: Jian-Dong
authors.initials: JD
authors.lastname: Li
authors.forename: Yong
authors.initials: Y
authors.lastname: Jiang
authors.forename: Shuang
authors.initials: S
authors.lastname: Huang
authors.forename: Ling-Yu
authors.initials: LY
authors.lastname: Chen
mesh_terms: D002478:Cells, Cultured; D000074749:Deubiquitinating Enzyme CYLD; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000187:drug effects* / Q000276:immunology*; D008070:Lipopolysaccharides / Q000276:immunology / Q000494:pharmacology*; D012475:Salmonella / Q000276:immunology; D015398:Signal Transduction / Q000187:drug effects / Q000276:immunology; D051196:Toll-Like Receptor 3 / Q000096:biosynthesis* / Q000276:immunology*; D025521:Tumor Suppressor Proteins / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects*
chemical_list: D008070:Lipopolysaccharides; C495344:TLR3 protein, human; D051196:Toll-Like Receptor 3; D025521:Tumor Suppressor Proteins; C409984:CYLD protein, human; D000074749:Deubiquitinating Enzyme CYLD