[Effects of bone morphogenic proteins-7 on production of collagen from hepatocytes and hepatic stellate cells during liver fibrosis].
OBJECTIVE
To study the effects of bone morphogenic proteins-7 (BMP-7) on the production of collagen from hepatocytes and hepatic stellate cells (HSC) during liver fibrosis, and the possible mechanism thereof.


METHODS
Ten SD rats underwent repeated peritoneal injection of pig serum twice a week for 8 weeks so as to establish liver fibrosis models. Another 5 rats were injected intraperitoneally with normal saline as control group. Then the rats were sacrificed with their livers taken out. Primary hepatocytes and HSC were isolated from the fibrotic livers and cultured. BMP-7 at the concentrations of 10, 50, or 100 mg/L was added into the culture media for 24 and 96 hours respectively. ELISA was used to detect the levels of collagen of type I, III, and IV. BMP-7 at the concentration of 50 mg/L was added into the culture media for 96 h, then immunofluorescence staining was conducted on the cells to examine the levels of TbetaR-I and TbetaR-II, TGF-beta1 receptors on the cell surface, and the Smad2/3 level. Real-time RT-PCR was used to detect the TGF-beta1 mRNA expression in the cells.


RESULTS
The levels of collagen of type I and III in the HSC treated by BMP-7 were all significantly lower than those in the control group especially 50 mg/L BMP-7 decreased the expression of collagen I by 40% +/- 6% (P < 0.01) and decreased the collagen III expression by 60% +/- 8% (P < 0.01), however, the levels of type IV collagen in the hepatocytes treated by BMP-7 were not significantly different from those of the control group. The levels of collagen of type I, III, and IV in the hepatocytes treated by BMP-7 were not significantly different from those of the control group. The impact of 50 mg/L BNP-7 on the HSC was stronger than that of the 10 mg/L BMP-7, however, not significantly different from that of the 100 mg/L BMP-7. There were not significant differences in the TbetaR-I and TbetaR-II levels in the HSC culture fluid treated by 50 mg/L BMP-7. 96 h after the treatment of 50 mg/L BMP-7 the Smad2/3 immunofluorescent strength in the HSC and hepatocytes decreased remarkably, and the TGF-beta1 level in the HSC decreased to the level 88% as high as that before treatment.


CONCLUSIONS
BMP-7 inhibits the production of type I, and III collagen in activated HSC with the possible mechanism of inhibition of phosphorylated Smad2/3 in HSCs and down-regulation of the expression of TGF-beta1.
Yang
Li
L
Department of Gastroenterology, Tongji Hosptal of Tongji University, Shanghai 200065, China.
Yang
Chang-Qing
CQ
Yuan
Min
M
Wang
Sheng-Lan
SL
Chang
Yi-Zhong
YZ
Xu
Li-Jun
LJ
Zhang
Zhao-Jie
ZJ
D000818:Animals; D055419:Bone Morphogenetic Protein 7 / Q000494:pharmacology*; D002478:Cells, Cultured; D003094:Collagen / Q000096:biosynthesis*; D005260:Female; D055166:Hepatic Stellate Cells / Q000187:drug effects / Q000378:metabolism*; D022781:Hepatocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008099:Liver / Q000166:cytology / Q000187:drug effects; D008106:Liver Cirrhosis, Experimental / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D051899:Smad2 Protein / Q000378:metabolism; D051900:Smad3 Protein / Q000378:metabolism
C525821:Bmp7 protein, rat; D055419:Bone Morphogenetic Protein 7; D051899:Smad2 Protein; D051900:Smad3 Protein; D003094:Collagen