[The role of thrombin on lung fibroblast growth and fibrosis in bleomycin-induced lung disorder].
In order to clarify the role of thrombin on the development of pulmonary fibrosis in diffuse interstitial lung diseases, we examined the relationship between fibroblast growth-stimulating activity (FGA) and thrombin activity in bronchoalveolar lavage fluid (BALF) from rats with bleomycin-induced interstitial lung disorders. Male Wistar strain rats (body weight about 200 g) were given a single intratracheal injection of 0.9 mg bleomycin, and bronchoalveolar lavage was performed on days 2, 6 and 15. The BALF was centrifuged at 250 X g for 10 min to remove cells, and then the supernatant was recentrifugation at 27,000 X g for 40 min to remove pulmonary surfactants. The supernatant (10 ml) was dialyzed overnight against distilled water, frozen at -70 degrees C, freeze-dried, and resuspended in 2 ml of Dulbecco's modified Eagle medium (concentrated 5-fold). The 5-fold concentrated BALF was added to rat lung fibroblast culture media, and assayed for cytotoxic activity and FGA. Thrombin activity in 250 X g supernatant was measured by using fluorescence assay with the synthetic peptide substrate, Boc-Val-Pro-Arg-4-methylcoumaryl-7-amide. Histological examination showed a prominent increase in fibroblast number in the pulmonary interstitium on day 6, and transformation of fibroblasts into mature forms, fibrocytes, on day 15. On day 2 after bleomycin administration, no FGA was seen but cytotoxic activity was detected in the BALF. On day 6, the cytotoxic activity was not found, whereas FGA showed a significantly higher level than the control value. On day 15, the FGA decreased to the control value.(ABSTRACT TRUNCATED AT 250 WORDS)
Tani
K
K
Third Department of Internal Medicine, School of Medicine, Tokushima University.
Yasuoka
S
S
Ogushi
F
F
Asada
K
K
Fujisawa
K
K
Ozaki
T
T
Ogura
T
T
Suzuki
K
K
D000645:Ammonium Sulfate / Q000378:metabolism; D000818:Animals; D001761:Bleomycin; D001992:Bronchoalveolar Lavage Fluid / Q000378:metabolism; D005346:Fibroblast Growth Factors / Q000378:metabolism*; D005355:Fibrosis; D006801:Humans; D008168:Lung / Q000473:pathology; D008297:Male; D011658:Pulmonary Fibrosis / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology*; D051381:Rats; D011919:Rats, Inbred Strains; D013917:Thrombin / Q000378:metabolism / Q000502:physiology*
D001761:Bleomycin; D005346:Fibroblast Growth Factors; D013917:Thrombin; D000645:Ammonium Sulfate