which may be modulated by the most potent fibrogenic cyto-Hepatic fibrosis, which may lead to cirrhosis, is associkine, transforming growth factor b 1 (TGF-b 1 ). 5,6 Hepatic fiated with most chronic liver diseases. Current therapies brosis is associated with an activation of lipocytes. 2 In hepatic for hepatic fibrosis are, however, generally ineffective.
fibrosis, an increase of desmin-(a marker of lipocytes) positive In this report we assessed the efficacy of the treatment cells is evident in the fibrotic areas and most of them are also of hepatic fibrosis with a naturally occurring deletion a-smooth muscle (sm)-actin-(a marker of activated lipocytes) variant of hepatocyte growth factor (dHGF). The adminpositive. 3,4,[7][8][9] TGF-b 1 is highly associated with hepatic fibroistration of dHGF increased liver weight and suppressed sis 10 and induces collagen formation by increasing procollathe increase of hepatic collagen content in rats treated gen messenger RNA (mRNA) levels. 11,12 In both schistomiasis with dimethylnitrosamine (DMN) to induce hepatic fiin mice and carbon tetrachloride-induced hepatic fibrosis in brosis. Furthermore, dHGF exerted its mitogenic and rats, fibrotic lesions are associated with an increase in procolantifibrogenic activities even after the liver fibrosis had lagen a1(I)
), been established with DMN. Northern blot analysis a1(IV) (Cola1 [IV]), and TGF-b 1 mRNAs. 10,13 In patients with showed that dHGF suppressed the increase of messenchronic hepatitis and cirrhosis, the level of TGF-b 1 mRNA ger RNA (mRNA) levels of procollagen a2(I), a1(III), a correlates with that of Cola1(I) mRNA, serum level of procol-1(IV), transforming growth factor b 1 (TGF-b 1 ), desmin (a lagen type III peptide, and histological activity index. 14 marker of hepatic lipocytes), and a-smooth muscle (sm)actin (a marker of activated hepatic lipocytes). In addition to suppressing the elevated TGF-b 1 mRNA level in hepatic fibrosis, dHGF had a potent ability to decrease Hepatocyte growth factor (HGF), a ligand for the c-met TGF-b 1 mRNA level even in a normal liver. Immunohisprotooncogene product, is a growth factor with multiple biotochemical analysis revealed that desmin-positive cells logical properties including mitogenic, motogenic, morphoand a-sm-actin-positive cells were increased in the hegenic, [15][16][17] and tumor cytotoxic activities, 18 and plays an im- patic fibrosis, whereas neither cells were seen in livers of portant role in liver regeneration. 17,19 A naturally occurring DMN-treated rats given dHGF. We conclude that dHGF splice variant of HGF lacks five consecutive amino acid resiprevents and improves the DMN-induced hepatic fibrodues in the first kringle domain. 20 This deletion variant of sis in rats by reducing mRNA levels of procollagens and hepatocyte growth factor (dHGF) is more mitogenic than TGF-b 1 , by inhibiting an activation of hepatic lipocytes, HGF for rat hepatocytes 20 and different from HGF in physicoand by stimulating liver regeneration. dHGF may be usechemical and immunological properties. 21
ful for and applicable to the treatment of fibrosis in
A recent approach to treat hepatic fibrosis is to use cytochronic liver diseases. (HEPATOLOGY 1996;24:636-642.) kines, e.g., interferons, that modulate extracellular matrix synthesis. 22 In this report, we studied the efficacy of dHGF administration for the treatment of liver fibrosis induced Hepatic fibrosis is a complex process that involves a marked accumulation of extracellular matrix components, ac-with dimethylnitrosamine (DMN) and used Northern hybridization and immunohistochemical staining to elucidate the tivation of cells capable of producing matrix materials, cytokine release, and tissue remodeling. The extracellular matrix antifibrogenic effect of dHGF on liver fibrosis. The administration of dHGF increased liver weight and suppressed the components are interstitial collagens (types I and III), basement membrane collagen (type IV), and noncollagenous gly-increase of hepatic collagen content in rats treated with DMN. Furthermore, dHGF exerted mitogenic and antifibro-coproteins, such as laminin and fibronectin. 1 Hepatic lipocytes (Ito cells, or fat-storing cells) are known as the primary genic activities even after the liver fibrosis had been established with DMN. This is the first demonstration of the effects cellular source of the matrix components in liver injury. 2 During liver injury lipocytes undergo activation, a process char-of HGFs on acceleration of recovery from the established liver fibrosis. acterized by stimulated proliferation and fibrogenesis, 1,3,4
MATERIALS AND METHODS
Treatment of Animals. Liver fibrosis was induced in male Wistar
Abbreviations: TGF-b1, transforming growth factor b1; sm, smooth muscle; mRNA, mesrats (7 weeks old, 180-200 g body weight) by administrating DMN senger RNA; Cola1(I), procallagen a1(I); Cola2(I), procollagen a2(I); Cola1(III), procollagen (1% in saline, 1 mL/100 g body weight, intraperitoneally) (Tokyo ka-a1(III); Cola1(IV), procollagen a1(IV); HGF, hepatocyte growth factor; dHGF, deletion variant of hepatocyte growth factor; DMN, dimethylnitrosamine; GAPDH, glyceraldhyde-3-sei, Tokyo, Japan) on 3 consecutive days a week for 4 weeks. 23 Aniphosphate dehydrogenase. mals were maintained on standard chow and water ad libitum and From the Research Institute of Life Science, Snow Brand Milk Products Co., Ltd., received humane care. The DMN-treated animals received vehicle Tochigi, 329-05, Japan.