Effects of lipopolysaccharide on platelet-derived growth factor isoform and receptor expression in cultured rat common bile duct fibroblasts and cholangiocytes.
OBJECTIVE
Little is known about the role of platelet-derived growth factor (PDGF) in biliary fibrosis in the setting of bacterial colonization of the biliary tree. We therefore sought to investigate whether exposure to bacterial lipopolysaccharide (LPS) alters PDGF isoform and receptor expression in cultured rat common bile duct fibroblasts (CBDF) and normal rat cholangiocytes (NRC).


METHODS
Collagen content in cells and media was assessed by colorimetric assay and gel electrophoresis. mRNA levels of PDGF-A and -B, and PDGF-Receptors (PDGF-R) alpha and beta were measured by relative quantitative real-time PCR. Protein levels of PDGF-AA, AB and BB were measured by ELISA, and PDGF-Ralpha and PDGF-Rbeta by Western blot.


RESULTS
In CBDF, LPS increased total soluble collagen synthesis and secretion. PDGF-Ralpha and beta mRNA and protein were also increased by LPS treatment in CBDF. Lipopolysaccharide treatment elicited an increase in PDGF-A and -B mRNA levels in CBDF. In NRC, levels of PDGF-AmRNAincreased in a dose-dependent fashion following LPS treatment, whereas PDGF-B mRNA showed no response. PDGF-AA secretion was higher by CBDF than by NRC. PDGF-BB levels were also higher in CBDF than in NRC. While PDGF-BB levels did not respond to LPS treatment in CBDF, there was a dosedependent response of this isoform to LPS in NRC. Intracellular and secreted PDGF-AB increased with LPS treatment in NRC.


CONCLUSIONS
These results support a model in which chronic bacterial colonization of the biliary tree induces fibrosis through PDGF-dependent mechanisms.
Kim
Tae-Hyeon
TH
Division of Gastroenterology, Department of Medicine, University of Washington and Veterans Affairs Puget Sound Health Care System, Seattle Division, Seattle, Washington 98195, USA.
Moon
Jong Ho
JH
Savard
Christopher E
CE
Kuver
Rahul
R
Lee
Sum P
SP
D000818:Animals; D000077214:Becaplermin; D002478:Cells, Cultured; D002761:Cholangitis / Q000378:metabolism / Q000473:pathology; D003094:Collagen / Q000235:genetics / Q000378:metabolism; D003135:Common Bile Duct / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D005355:Fibrosis; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008297:Male; D010982:Platelet-Derived Growth Factor / Q000235:genetics / Q000378:metabolism*; D020574:Proto-Oncogene Proteins c-sis / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020796:Receptor, Platelet-Derived Growth Factor alpha / Q000378:metabolism; D020797:Receptor, Platelet-Derived Growth Factor beta / Q000378:metabolism; D017479:Receptors, Platelet-Derived Growth Factor / Q000235:genetics / Q000378:metabolism*
D008070:Lipopolysaccharides; D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D012333:RNA, Messenger; C075278:platelet-derived growth factor A; C095477:platelet-derived growth factor AB; D000077214:Becaplermin; D003094:Collagen; D020796:Receptor, Platelet-Derived Growth Factor alpha; D020797:Receptor, Platelet-Derived Growth Factor beta; D017479:Receptors, Platelet-Derived Growth Factor