title: Size-dependent attenuation of TLR9 signaling by gold nanoparticles in macrophages.
abstract: Gold nanoparticles (GNPs), which are generally thought to be bio-inert and non-cytotoxic, have become one of the most ideal nanomaterials for medical applications. Once engulfed by phagocytes, the immunological effects of GNPs are still of concern and require detailed investigation. Therefore, this study explored the immunological significance of GNPs on TLR-mediated innate immunity in murine macrophages. GNP causes specific inhibition of TLR9 (CpG oligodeoxynucleotides; CpG-ODNs) signal in macrophages. The impaired CpG-ODN-induced TNF-α production is GNP concentration- and size-dependent in murine Raw264.7 cells: a GNP of 4 nm in size is more potent than a GNP of 11, 19, 35, or 45 nm in size. Consistent with cytokine inhibition, the CpG-ODN-induced phosphorylation of NF-κB and JNK as well as NF-κB activation are suppressed by GNPs. GNPs accumulate in lysosomes after phagocytosis and also increase TLR9-associated lysosomal cathepsin expression and activities, but this is irrelevant to TLR9 inhibition by GNPs in our studies. In addition, GNPs affected TLR9 translocation in response to CpG-ODNs and to phagosomes. Further exploring how GNPs inhibited TLR9 function, we found that GNPs could bind to high-mobility group box-1 (which is involved in the regulation of TLR9 signaling) inside the lysosomes. The current studies demonstrate that size-dependent inhibition of TLR9 function by GNP may be attributed to its binding to high-mobility group box-1.
authors.affiliation: Department of Microbiology and Immunology, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Chiau-Yuang
authors.initials: CY
authors.lastname: Tsai
authors.forename: Shiou-Ling
authors.initials: SL
authors.lastname: Lu
authors.forename: Chia-Wen
authors.initials: CW
authors.lastname: Hu
authors.forename: Chen-Sheng
authors.initials: CS
authors.lastname: Yeh
authors.forename: Gwo-Bin
authors.initials: GB
authors.lastname: Lee
authors.forename: Huan-Yao
authors.initials: HY
authors.lastname: Lei
mesh_terms: D000818:Animals; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D005260:Female; D006046:Gold; D024243:HMGB1 Protein / Q000276:immunology; D008247:Lysosomes / Q000276:immunology; D008264:Macrophages / Q000166:cytology / Q000276:immunology*; D053768:Metal Nanoparticles; D051379:Mice; D016328:NF-kappa B / Q000276:immunology; D009838:Oligodeoxyribonucleotides / Q000494:pharmacology; D010316:Particle Size; D010587:Phagocytosis / Q000187:drug effects / Q000276:immunology*; D010588:Phagosomes / Q000276:immunology; D010766:Phosphorylation / Q000187:drug effects / Q000276:immunology; D015398:Signal Transduction / Q000187:drug effects / Q000276:immunology*; D051217:Toll-Like Receptor 9 / Q000276:immunology*; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology
chemical_list: C408982:CPG-oligonucleotide; D024243:HMGB1 Protein; D016328:NF-kappa B; D009838:Oligodeoxyribonucleotides; C495370:Tlr9 protein, mouse; D051217:Toll-Like Receptor 9; D014409:Tumor Necrosis Factor-alpha; D006046:Gold