TLR3-mediated synthesis and release of eotaxin-1/CCL11 from human bronchial smooth muscle cells stimulated with double-stranded RNA.
Respiratory infections with RNA viruses, such as rhinovirus or respiratory syncytial virus, are a major cause of asthma exacerbation, accompanied by enhanced neutrophilic and/or eosinophilic inflammation of the airways. We studied the effects of dsRNA synthesized during RNA virus replication, and of its receptor, TLR3, on the synthesis of eosinophilic chemokines in bronchial smooth muscle cells (BSMC). Synthetic dsRNA, polyinosinic-cystidic acid (poly(I:C)), induced the synthesis of eosinophilic chemokines, eotaxin-1/CCL11 and RANTES/CCL5, from primary cultures of human BSMC, and IL-4 increased synergistically the synthesis of poly(I:C)-induced CCL11. A robust eosinophil chemotactic activity was released from BSMC stimulated with poly(I:C) and IL-4, which was mostly inhibited by preincubation with an anti-CCL11, but not with an anti-CCL5 Ab. Although the immunoreactivity of TLR3 was detectable on the cellular surface of BSMC by flow cytometric analysis, pretreatment with an anti-TLR3-neutralizing Ab failed to block the poly(I:C)-induced synthesis of CCL11. We have determined by confocal laser-scanning microscopy that the immunoreactivity of TLR3 was aggregated intracellularly in poly(I:C)-stimulated BSMC, colocalizing with fluorescein-labeled poly(I:C). The synthesis of CCL11 was prominently inhibited by the transfection of TLR3-specific small interfering RNA or by bafilomycin A1, an endosomal acidification inhibitor, further supporting the essential role played by intracellular TLR3 in the synthesis of poly(I:C)-induced CCL11 in BSMC. In conclusion, these observations suggest that, by activating intracellular TLR3 in BSMC, respiratory RNA virus infections stimulate the production of CCL11 and enhance eosinophilic inflammation of the airways in the Th2-dominant microenvironment.
Niimi
Kyoko
K
Division of Pulmonary Medicine, Department of Medicine, Keio University School of Medicine, Tokyo, Japan.
Asano
Koichiro
K
Shiraishi
Yoshiki
Y
Nakajima
Takeshi
T
Wakaki
Misa
M
Kagyo
Junko
J
Takihara
Takahisa
T
Suzuki
Yusuke
Y
Fukunaga
Koichi
K
Shiomi
Tetsuya
T
Oguma
Tsuyoshi
T
Sayama
Koichi
K
Yamaguchi
Kazuhiro
K
Natori
Yukikazu
Y
Matsumoto
Misako
M
Seya
Tsukasa
T
Yamaya
Mutsuo
M
Ishizaka
Akitoshi
A
D001980:Bronchi / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D002478:Cells, Cultured; D054413:Chemokine CCL11; D018946:Chemokine CCL5 / Q000235:genetics / Q000378:metabolism; D019742:Chemokines, CC / Q000235:genetics / Q000378:metabolism*; D002634:Chemotaxis, Leukocyte; D004804:Eosinophils / Q000276:immunology; D006801:Humans; D015847:Interleukin-4 / Q000494:pharmacology; D032389:Myocytes, Smooth Muscle / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D011070:Poly I-C / Q000494:pharmacology; D012328:RNA Viruses / Q000276:immunology*; D012330:RNA, Double-Stranded / Q000494:pharmacology*; D034741:RNA, Small Interfering / Q000494:pharmacology; D051196:Toll-Like Receptor 3 / Q000032:analysis / Q000037:antagonists & inhibitors / Q000378:metabolism*
C515456:CCL11 protein, human; D054413:Chemokine CCL11; D018946:Chemokine CCL5; D019742:Chemokines, CC; D012330:RNA, Double-Stranded; D034741:RNA, Small Interfering; C495344:TLR3 protein, human; D051196:Toll-Like Receptor 3; D015847:Interleukin-4; D011070:Poly I-C