Expression of platelet-derived growth factor in newly formed cholangiocytes during experimental biliary fibrosis in rats.
OBJECTIVE
Chronic cholestasis stimulates a fibroductular reaction which may progress to secondary biliary fibrosis and cirrhosis. Since platelet-derived growth factor has been indicated as a major fibrogenic factor in chronic liver disease, we analyzed its expression and that of its receptor beta subunit in a rat model of chronic cholestasis.


METHODS
Liver tissue samples collected at 7, 10, 21, and 28 days after induction of cholestasis obtained by bile duct ligation, were analyzed by immunohistochemistry, in situ hybridization and RNase protection assay for the expression of platelet-derived growth factor (PDGF)-B chain and receptor beta subunit. Furthermore, the expression of PDGF-B chain mRNA was analyzed in highly purified cholangiocytes from normal and cholestatic rat liver.


RESULTS
In cholestatic liver, platelet-derived growth factor-BB and B chain mRNA expression increased up to 4 weeks in epithelial cells of proliferating bile ducts, and periductular mesenchymal cells. The increased expression of PDGF-B chain mRNA was confirmed in highly purified cholangiocytes obtained from normal and cholestatic rat liver. The expression of the receptor beta subunit progressively increased after induction of cholestasis and was mainly localized to desmin-positive periductular hepatic stellate cells.


CONCLUSIONS
These data suggest that platelet-derived growth factor-B chain can be synthesized by cholangiocytes during chronic cholestasis. The presence of its receptor on periductular hepatic stellate cells raises the possibility that, in this experimental setting, this cytokine might contribute to fibrogenesis in vivo.
Grappone
C
C
Dipartimento di Fisiopatologia Clinica-Sezione di Gastroenterologia, Universita' di Firenze, Italy.
Pinzani
M
M
Parola
M
M
Pellegrini
G
G
Caligiuri
A
A
DeFranco
R
R
Marra
F
F
Herbst
H
H
Alpini
G
G
Milani
S
S
D000818:Animals; D000077214:Becaplermin; D001652:Bile Ducts / Q000378:metabolism* / Q000473:pathology; D002779:Cholestasis / Q000378:metabolism* / Q000473:pathology; D002908:Chronic Disease; D003135:Common Bile Duct / Q000502:physiology; D005260:Female; D005786:Gene Expression Regulation; D017403:In Situ Hybridization; D008099:Liver / Q000378:metabolism* / Q000473:pathology; D010982:Platelet-Derived Growth Factor / Q000096:biosynthesis / Q000235:genetics; D020574:Proto-Oncogene Proteins c-sis; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D014158:Transcription, Genetic
D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D012333:RNA, Messenger; D000077214:Becaplermin