Lipopolysaccharide induced connective tissue growth factor gene expression in human bronchial epithelial cells.
OBJECTIVE
Connective tissue growth factor (CTGF) is up-regulated in the lungs of patients with chronic obstructive pulmonary disease (COPD). Cigarette smoke and repeated bacterial infections, both of which are rich sources of LPS, are major causes of COPD. The high levels of LPS in lung epithelial lining fluid also suggest that it may have a considerable impact on the airway epithelium, in terms of cytokine and growth factor production. The aim of this study was to clarify the mechanism of LPS-induced CTGF expression in bronchial epithelial cells.


METHODS
The expression and transcriptional regulation of the CTGF gene were assessed using the cultured human bronchial epithelial cell line, BEAS-2B.


RESULTS
LPS significantly up-regulated CTGF mRNA expression in a dose-dependent fashion, with 100 microg/mL LPS causing a twofold increase after 2 h. CTGF protein expression was also up-regulated by LPS after 8 h. Transforming growth factor-beta1 mRNA expression was not changed by LPS treatment. A pharmacological inhibitor of nuclear factor (NF)-kappaB, MG132, inhibited LPS-induced CTGF mRNA expression. Furthermore, luciferase assays demonstrated that deletion of base pairs -253 to -53 from the CTGF promoter, where the Smad and proximal NF-kappaB binding sites are located, decreased the induction of CTGF by LPS. After stimulation with LPS, the p65 subunit of NF-kappaB was shown to be bound to the CTGF promoter in vitro and in situ.


CONCLUSIONS
LPS directly induced CTGF expression in bronchial epithelial cells, independently of transforming growth factor-beta1, suggesting a possible mechanism for airway remodelling in COPD that is induced by smoking and repeated bacterial infections.
Nishioka
Michiyoshi
M
Department of Respiratory Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Ogawa
Emiko
E
Kinose
Daisuke
D
Haruna
Akane
A
Ohara
Tadashi
T
Ito
Isao
I
Hoshino
Yuma
Y
Ito
Yutaka
Y
Matsumoto
Hisako
H
Niimi
Akio
A
Mio
Tadashi
T
Chin
Kazuo
K
Hirai
Toyohiro
T
Muro
Shigeo
S
Mishima
Michiaki
M
D001980:Bronchi / Q000378:metabolism*; D002478:Cells, Cultured; D055513:Connective Tissue Growth Factor / Q000235:genetics*; D004847:Epithelial Cells / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D007976:Leupeptins / Q000008:administration & dosage / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000378:metabolism*; D016328:NF-kappa B / Q000037:antagonists & inhibitors; D011401:Promoter Regions, Genetic; D029424:Pulmonary Disease, Chronic Obstructive / Q000235:genetics / Q000378:metabolism*; D017384:Sequence Deletion
D007976:Leupeptins; D008070:Lipopolysaccharides; D016328:NF-kappa B; D055513:Connective Tissue Growth Factor; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde