title: Bacterial flagellin induces IL-6 expression in human basophils.
abstract: Binding of allergen to IgE on basophils positively affects allergic inflammation by releasing inflammatory mediators. Recently, basophils were shown to express pattern-recognition receptors, such as toll-like receptors (TLRs), for recognizing microbe-associated molecular patterns (MAMPs) that are independent of allergen-IgE binding. In this study, we investigated whether MAMP alone can induce IL-6 production in a human basophil cell line, KU812. Stimulation with flagellin in the absence of allergen-IgE association induced IL-6 expression in KU812 cells, while stimulation with lipoteichoic acid, peptidoglycan, or poly I:C did not under the same condition. Flagellin-induced IL-6 expression was also observed in human primary basophils. Flow cytometric analysis showed that KU812 cells expressed flagellin-recognizing TLR5 both on the cell surface and in the cytoplasm while TLR2 and TLR3 were observed only in the cytoplasm. We further demonstrated that although flagellin augmented the phosphorylation of mitogen-activated protein kinases including p38 kinase, ERK, and JNK, flagellin-induced IL-6 production was attenuated by inhibitors for p38 kinase and ERK, but not by JNK inhibitors. In addition, flagellin enhanced phosphorylation of signaling molecules including CREB, PKCδ, and AKT. The inhibitors for PKA and PKC also showed inhibitory effects. Interestingly, flagellin-induced IL-6 production was further enhanced by pretreatment with inhibitors for PI3K, implying that PI3K negatively affects the flagellin-induced IL-6 production. Furthermore, DNA binding activities of NF-κB, AP-1, and CREB, which play pivotal roles in the induction of IL-6 gene expression, were increased by flagellin. These results suggest that flagellin alone is sufficient to induce IL-6 gene expression via TLR5 signaling pathways in human basophils.
authors: Department of Oral Microbiology and Immunology, DRI, and BK21 Plus Program, School of Dentistry, Seoul National University, Seoul 110-749, Republic of Korea; Division of High-risk Pathogen Research, Center for Infectious Diseases, Korean National Institute of Health, Cheongju-si, Chungcheongbuk-do 361-709, Republic of Korea.
authors: Jun Ho
authors: JH
authors: Jeon
authors: Department of Oral Microbiology and Immunology, DRI, and BK21 Plus Program, School of Dentistry, Seoul National University, Seoul 110-749, Republic of Korea.
authors: Ki Bum
authors: KB
authors: Ahn
authors: Department of Oral Microbiology and Immunology, DRI, and BK21 Plus Program, School of Dentistry, Seoul National University, Seoul 110-749, Republic of Korea.
authors: Sun Kyung
authors: SK
authors: Kim
authors: Department of Oral Microbiology and Immunology, DRI, and BK21 Plus Program, School of Dentistry, Seoul National University, Seoul 110-749, Republic of Korea.
authors: Jintaek
authors: J
authors: Im
authors: Department of Agricultural Biotechnology and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul 151-921, Republic of Korea.
authors: Cheol-Heui
authors: CH
authors: Yun
authors: Department of Oral Microbiology and Immunology, DRI, and BK21 Plus Program, School of Dentistry, Seoul National University, Seoul 110-749, Republic of Korea. Electronic address: shhan-mi@snu.ac.kr.
authors: Seung Hyun
authors: SH
authors: Han
mesh_terms: D000485:Allergens / Q000276:immunology*; D001491:Basophils / Q000276:immunology*; D002460:Cell Line; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D004268:DNA-Binding Proteins / Q000235:genetics; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D005408:Flagellin / Q000276:immunology*; D006801:Humans; D006967:Hypersensitivity / Q000276:immunology*; D007073:Immunoglobulin E / Q000276:immunology; D007249:Inflammation / Q000276:immunology; D015850:Interleukin-6 / Q000096:biosynthesis* / Q000235:genetics; D016209:Interleukin-8 / Q000096:biosynthesis; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D016328:NF-kappa B / Q000235:genetics; D010457:Peptidoglycan / Q000494:pharmacology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D011070:Poly I-C / Q000494:pharmacology; D051745:Protein Kinase C-delta / Q000037:antagonists & inhibitors / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D051192:Receptors, Pattern Recognition / Q000276:immunology; D013682:Teichoic Acids / Q000494:pharmacology; D051195:Toll-Like Receptor 2 / Q000096:biosynthesis; D051196:Toll-Like Receptor 3 / Q000096:biosynthesis; D051198:Toll-Like Receptor 5 / Q000096:biosynthesis; D018808:Transcription Factor AP-1 / Q000235:genetics; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D000485:Allergens; C115163:CREB1 protein, human; C508606:CXCL8 protein, human; D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins; C508600:IL6 protein, human; D015850:Interleukin-6; D016209:Interleukin-8; D008070:Lipopolysaccharides; D016328:NF-kappa B; D010457:Peptidoglycan; D000081082:Phosphoinositide-3 Kinase Inhibitors; D012333:RNA, Messenger; D051192:Receptors, Pattern Recognition; C495342:TLR2 protein, human; C495344:TLR3 protein, human; C495346:TLR5 protein, human; D013682:Teichoic Acids; D051195:Toll-Like Receptor 2; D051196:Toll-Like Receptor 3; D051198:Toll-Like Receptor 5; D018808:Transcription Factor AP-1; D005408:Flagellin; D007073:Immunoglobulin E; C009900:lipoteichoic acid; D051057:Proto-Oncogene Proteins c-akt; D017868:Cyclic AMP-Dependent Protein Kinases; D051745:Protein Kinase C-delta; D048049:Extracellular Signal-Regulated MAP Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D011070:Poly I-C
keywords: Basophils; Flagellin; IL-6; KU812; TLR5