[Effect of silencing connective tissue growth factor on rat liver fibrosis and the accumulation of extracellular matrix].
OBJECTIVE
To investigate the anti-fibrogenesis property of intraportal vein injection of small interfering RNA targeting connective tissue growth factor (CTGF) in a rat model of liver fibrosis and its effect on the accumulation of extracellular matrix (ECM).


METHODS
Thirty male rats were randomly divided into five groups. Some rats received CCl4 subcutaneously every three days for 6 consecutive weeks, and in the meantime they also received either siRNA targeting CTGF (preventive group), saline (model group) or siRNA (siRNA control group) by intraportal vein injections. Other rats received CCl4 by subcutaneous injection for 2 weeks, followed by CCl4 and CTGF siRNA intraportal vein injection for 4 more weeks (as treatment group). The expressions of CTGF and type I and III collagen genes were detected by means of reverse transcription-polymerase chain reaction (RT-PCR) and/or Western blot respectively. Hepatic histology was evaluated by HE and Sirius red stained sections. The collagen staining areas were measured quantitatively using a computer-aided manipulator with slight modifications. Serum procollagen type III and hyaluronic acid were determined by radioimmunoassay.


RESULTS
Six weeks after CCl4 injection, prominent upregulation of gene expressions of CTGF, type I and III collagen, and laminin in saline or siRNA-treated rat livers were observed. The expressions of CTGF at mRNA and protein level and type I and III collagen at mRNA level were markedly reduced in rats with CTGF siRNA treated for four or six weeks. Expressions of CTGF at mRNA and protein levels decreased by 76%+/-8%, 80%+/-3% (F = 68.630) and 95%+/-2%, 93%+/-3% (F = 21.234, P < 0.01); type I and III collagen and laminin at mRNA levels decreased by 74%+/-8%, 78%+/-8%, 31%+/-7% and 57%+/-6%, 59%+/-10%, 43%+/-9% (F = 24.219, 16.315, 9.716, P < 0.01) compared with rats in the model group at 72 h. The CTGF siRNA treatment markedly reduced serum levels of procollagen type III and hyaluronic acid and the degrees of liver fibrosis.


CONCLUSIONS
Intraportal vein siRNA injection targeting CTGF could significantly inhibit CTGF gene expression in rats, thereby attenuating liver fibrosis by reducing ECM accumulation.
Li
Guang-ming
GM
Department of Gastroenterology, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Li
Ding-guo
DG
Xie
Qing
Q
Shi
Yi
Y
Jiang
Shan
S
Zhou
Hui-juan
HJ
Lu
Han-ming
HM
Jin
You-xin
YX
D000818:Animals; D002251:Carbon Tetrachloride; D055513:Connective Tissue Growth Factor / Q000378:metabolism*; D005109:Extracellular Matrix / Q000378:metabolism*; D020868:Gene Silencing; D008099:Liver / Q000378:metabolism / Q000473:pathology; D008106:Liver Cirrhosis, Experimental / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology*; D008297:Male; D034741:RNA, Small Interfering; D051381:Rats; D017207:Rats, Sprague-Dawley
C526316:CCN2 protein, rat; D034741:RNA, Small Interfering; D055513:Connective Tissue Growth Factor; D002251:Carbon Tetrachloride