[Kinetics and mechanism in bleomycin-induced murine pulmonary fibrosis model].
OBJECTIVE
To investigate the kinetics of pathogenesis of bleomycin induced pulmonary fibrosis and its mechanism in mice.


METHODS
Thirty six male ICR mice were randomized as a negative control (NC) group and pulmonary fibrosis model (FM) groups (FMA, FMB, FMC, FMD, FME sub groups). Except for NC group, mice in the other groups were given bleomycin by nasal instillation. Animals in each group were sacrificed on day 6, 14, 21, 28 and 35, respectively. T lymphocytes were quantified for Th1/Th2 and Tc1/Tc2 by flow cytometry. Accumulation of inflammatory cells in bronchioalveolar lavage fluid (BALF) was quantified by cell count. The sections of the right lung were stained with either hematoxylin eosin (HE) or Masson trichrome. The left lung was weighed and its hydroxyproline (HYP) content was assayed. Multi cytokine expression in lung tissue was assayed by semi quantitative reverse transcription polymerase chain reaction (RT-PCR). On day 35, the tidal volume (V(T)), forced expiratory volume in 1 second/forced vital capacity (FEV 0.1/FVC), static compliance (Cst) of mice were determined before they were sacrificed.


RESULTS
(1)The total cell number in BALF in pulmonary fibrosis groups was statistically significantly higher than that in NC group (all P<0.01), and HYP content in lung tissue in pulmonary fibrosis groups was statistically significantly increased than that in NC group except for group FMA (all P<0.01). (2)V(T) and Cst in FME group were statistically significantly decreased than those in NC group (both P<0.01), and FEV 0.1/FVC was statistically significantly increased (P<0.05). (3)Th1 and Tc1 were demonstrated as the dominant expression in the acute inflammatory stage; Th2 and Tc2 were the dominant expression in the fibrosis forming stage, and then Th1 and Tc1 were again the dominant expression at the terminal stage of pulmonary fibrosis. (4)Compared with the content of cytokine in the lung in NC group, the expression of transforming growth factor-beta1 (TGF-beta1) and tissue inhibitor of metalloproteinase-1 (TIMP-1) mRNA were significantly higher in FM groups (all P<0.01).


CONCLUSIONS
The changes in lung function of bleomycin-induced pulmonary fibrosis in mice are typical of that of restrictive ventilatory disorder. Th2, Tc2 and fibrotic promoting growth factors (TGF-beta1, TIMP-1, etc.) play pivotal roles in the pathogenesis of pulmonary fibrotic process.
Hu
Ping
P
Department of Respiratory Medicine, People's Hospital, Peking University, Beijing 100044, China. huping_wind@yahoo.com.cn
Gao
Zhan-cheng
ZC
D000818:Animals; D001761:Bleomycin / Q000633:toxicity*; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D004195:Disease Models, Animal; D006909:Hydroxyproline / Q000378:metabolism; D008168:Lung / Q000378:metabolism / Q000473:pathology*; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D011658:Pulmonary Fibrosis / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology*; D011897:Random Allocation; D018418:Th2 Cells / Q000378:metabolism; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000378:metabolism
C508961:Tgfb1 protein, mouse; D019715:Tissue Inhibitor of Metalloproteinase-1; D053773:Transforming Growth Factor beta1; D001761:Bleomycin; D006909:Hydroxyproline