Expression of toll-like receptor 2 and 4 in lipopolysaccharide-induced lung injury in mouse.
Pattern recognition receptors, which include the toll-like receptors (TLRs), are considered to play an important role in the response against lipopolysaccharide (LPS). In this study, we performed a reverse transcriptase/polymerase chain reaction (RT-PCR) study, Western analysis, immunohistochemical staining, and RT-PCR-amplified in situ hybridization of TLR2 and TLR4 in the case of LPS-induced lung injury. The expression of TLR2 and TLR4 increased in the lung rapidly after LPS inhalation and peaked at 24 h, followed by a gradual decrease. TLR2 and TLR4 expression was observed on the bronchial epithelium and tissue macrophages. In the early hours after inhalation of fluorescein-isothiocyanate (FITC)-labeled LPS, LPS was detected mainly on the bronchial epithelium and on a few of tissue macrophages. One day after inhalation, the LPS signals disappeared in the lungs of the mice, except for a few alveolar macrophages. The expression of TLR2, TLR4, and CD14 was coincident with the signals of FITC-labeled LPS. Instillation of liposome-encapsulated dichloromethylene diphosphonate induced a significant decrease in alveolar macrophages. In the macrophage-depleted mice, however, expression of TLR2 and TLR4 mRNA or protein was slightly suppressed in the lung after LPS inhalation. These data suggest that the bronchial epithelium and macrophages play crucial roles in LPS-induced lung injury through TLR2 and TLR4.
Saito
Takuma
T
Division of Cellular and Molecular Pathology, Department of Cellular Function, Niigata University Graduate School of Medical and Dental Sciences, Asahimachi-dori 1, Niigata, 951-8510, Japan.
Yamamoto
Takashi
T
Kazawa
Toshihiro
T
Gejyo
Humitake
H
Naito
Makoto
M
D000818:Animals; D015153:Blotting, Western; D001980:Bronchi / Q000166:cytology; D004848:Epithelium / Q000378:metabolism; D005260:Female; D016650:Fluorescein-5-isothiocyanate; D005456:Fluorescent Dyes; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D018950:Lipopolysaccharide Receptors / Q000187:drug effects / Q000378:metabolism; D008070:Lipopolysaccharides / Q000378:metabolism / Q000633:toxicity*; D008168:Lung / Q000378:metabolism* / Q000503:physiopathology*; D008264:Macrophages / Q000378:metabolism; D051379:Mice; D008813:Mice, Inbred ICR; D018613:Microscopy, Confocal; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors
D005456:Fluorescent Dyes; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D016650:Fluorescein-5-isothiocyanate