Hepatocellular hypoxia-induced vascular endothelial growth factor expression and angiogenesis in experimental biliary cirrhosis.
We tested the potential role of vascular endothelial growth factor (VEGF) and of fibroblast growth factor-2 (FGF-2) in the angiogenesis associated with experimental liver fibrogenesis induced by common bile duct ligation in Sprague-Dawley rats. In normal rats, VEGF and FGF-2 immunoreactivities were restricted to less than 3% of hepatocytes. One week after bile duct ligation, hypoxia was demonstrated by the immunodetection of pimonidazole adducts unevenly distributed throughout the lobule. After 2 weeks, hypoxia and VEGF expression were detected in >95% of hepatocytes and coexisted with an increase in periportal vascular endothelial cell proliferation, as ascertained by Ki67 immunolabeling. Subsequently, at 3 weeks the density of von Willebrand-labeled vascular section in fibrotic areas significantly increased. Semiquantitative reverse transcription polymerase chain reaction showed that VEGF(120) and VEGF(164) transcripts, that correspond to secreted isoforms, increased within 2 weeks, while VEGF(188) transcripts remained unchanged. FGF-2 mainly consisting of a 22-kd isoform, according to Western blot, was identified by immunohistochemistry in 49% and 100% of hepatocytes at 3 and 7 weeks, respectively. Our data provide evidence that in biliary-type liver fibrogenesis, angiogenesis is stimulated primarily by VEGF in response to hepatocellular hypoxia while FGF-2 likely contributes to the maintenance of angiogenesis at later stages.
Rosmorduc
O
O
Service d'Hépatogastroentérologie, INSERM U 402, Paris, France. olivier.rosmorduc@sat.ap-hop-paris.fr
Wendum
D
D
Corpechot
C
C
Galy
B
B
Sebbagh
N
N
Raleigh
J
J
Housset
C
C
Poupon
R
R
D000818:Animals; D015153:Blotting, Western; D015687:Cell Hypoxia; D016228:Endothelial Growth Factors / Q000096:biosynthesis*; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism; D007150:Immunohistochemistry; D019394:Ki-67 Antigen / Q000096:biosynthesis; D008105:Liver Cirrhosis, Biliary / Q000378:metabolism* / Q000473:pathology; D008106:Liver Cirrhosis, Experimental / Q000378:metabolism* / Q000473:pathology; D008222:Lymphokines / Q000096:biosynthesis*; D008297:Male; D009389:Neovascularization, Pathologic / Q000378:metabolism* / Q000473:pathology; D009593:Nitroimidazoles / Q000378:metabolism; D020033:Protein Isoforms / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
D016228:Endothelial Growth Factors; D019394:Ki-67 Antigen; D008222:Lymphokines; D009593:Nitroimidazoles; D020033:Protein Isoforms; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D016222:Fibroblast Growth Factor 2; C033815:pimonidazole