Toll-like receptor 3 stimulation causes corticosteroid-refractory airway neutrophilia and hyperresponsiveness in mice.
BACKGROUND
RNA virus infections, such as rhinovirus and respiratory syncytial virus, induce exacerbations in patients with COPD and asthma, and the inflammation is corticosteroid refractory. The main aim of this study is to establish a murine model induced by a Toll-like receptor 3 (TLR3) agonist, an RNA virus mimic, and investigate the response to corticosteroid.


METHODS
A/J mice were given polyinosinic-polycytidylic acid (poly[I:C]), a TLR3 agonist, intranasally, in the presence or absence of cigarette smoke exposure. Inflammatory cell accumulation and C-X-C motif chemokine (CXCL) 1, interferon (IFN), and CXCL10 production in BAL fluid (BALF) were determined by flow cytometry and enzyme-linked immunosorbent assay, respectively, and airway hyperresponsiveness (AHR) to histamine/methacholine was determined by a two-chambered, double-flow plethysmography system. BALB/c and C57BL/6J mice were also used for comparisons.


RESULTS
Intranasal treatment of poly(I:C) significantly induced airway neutrophilia; production of CXCL1, IFN-β, and CXCL10; and necrotic cell accumulation in BALF. It also increased airway responsiveness to histamine or methacholine inhalation. This poly(I:C)-dependent airway inflammation and AHR was not inhibited by the corticosteroid fluticasone propionate (FP) (up to 0.5 mg/mL intranasal), although FP strongly inhibited lipopolysaccharide (TLR4 agonist)-induced airway neutrophilia. Furthermore, cigarette smoke exposure significantly increased TLR3 expression in murine lung tissue and exacerbated poly(I:C)-induced neutrophilia and AHR.


CONCLUSIONS
These results suggest that TLR3 stimulation is involved in corticosteroid-refractory airway inflammation in lung, which is enhanced by cigarette smoking, and this may provide a model for understanding virus-induced exacerbations in COPD and their therapy.
Department of Physiology and Anatomy, Nihon University School of Pharmacy, Funabashi, Chiba, Japan.
Genki
G
Kimura
Department of Physiology and Anatomy, Nihon University School of Pharmacy, Funabashi, Chiba, Japan.
Keitaro
K
Ueda
Department of Physiology and Anatomy, Nihon University School of Pharmacy, Funabashi, Chiba, Japan.
Shouichi
S
Eto
Department of Physiology and Anatomy, Nihon University School of Pharmacy, Funabashi, Chiba, Japan.
Yuji
Y
Watanabe
Department of Physiology and Anatomy, Nihon University School of Pharmacy, Funabashi, Chiba, Japan.
Takashi
T
Masuko
Department of Physiology and Anatomy, Nihon University School of Pharmacy, Funabashi, Chiba, Japan.
Tadashi
T
Kusama
Airway Disease Section, National Heart and Lung Institute, Imperial College, London, England.
Peter J
PJ
Barnes
Airway Disease Section, National Heart and Lung Institute, Imperial College, London, England.
Kazuhiro
K
Ito
Department of Physiology and Anatomy, Nihon University School of Pharmacy, Funabashi, Chiba, Japan. Electronic address: kizawa.yasuo@nihon-u.ac.jp.
Yasuo
Y
Kizawa
D000281:Administration, Intranasal; D000305:Adrenal Cortex Hormones / Q000627:therapeutic use*; D000730:Androstadienes / Q000627:therapeutic use; D000818:Animals; D016535:Bronchial Hyperreactivity / Q000139:chemically induced / Q000188:drug therapy* / Q000378:metabolism; D054357:Chemokine CXCL10 / Q000378:metabolism; D019743:Chemokines, CXC / Q000378:metabolism; D003907:Dexamethasone / Q000627:therapeutic use; D004195:Disease Models, Animal; D004351:Drug Resistance / Q000187:drug effects; D000068298:Fluticasone; D016899:Interferon-beta / Q000378:metabolism; D007960:Leukocyte Disorders / Q000139:chemically induced / Q000188:drug therapy* / Q000473:pathology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009504:Neutrophils / Q000473:pathology; D011070:Poly I-C / Q000008:administration & dosage / Q000009:adverse effects* / Q000494:pharmacology; D051196:Toll-Like Receptor 3 / Q000819:agonists* / Q000502:physiology; D016896:Treatment Outcome
D000305:Adrenal Cortex Hormones; D000730:Androstadienes; D054357:Chemokine CXCL10; D019743:Chemokines, CXC; C485433:Cxcl10 protein, mouse; C519703:TLR3 protein, mouse; D051196:Toll-Like Receptor 3; D016899:Interferon-beta; D003907:Dexamethasone; D000068298:Fluticasone; D011070:Poly I-C