Regenerative and fibrotic pathways in canine hepatic portosystemic shunt and portal vein hypoplasia, new models for clinical hepatocyte growth factor treatment.
BACKGROUND
We analyzed two spontaneous dog diseases characterized by subnormal portal perfusion and reduced liver growth: (i) congenital portosystemic shunts (CPSS) without fibrosis and (ii) primary portal vein hypoplasia (PPVH), a disease associated with fibrosis. These pathologies, that lack inflammation or cholestasis, may represent simplified models to study liver growth and fibrosis. To investigate the possible use of those models for hepatocyte growth factor (HGF) treatment, we studied the functionality of HGF signaling in CPSS and PPVH dogs and compared this to aged-matched healthy controls.


RESULTS
We used quantitative real-time polymerase chain reaction (Q-PCR) to analyze the mRNA expression of HGF, transforming growth factor beta1 (TGF-beta1), and relevant mediators in liver biopsies from cases with CPSS or PPVH, in comparison with healthy control dogs. CPSS and PPVH were associated with a decrease in mRNA expression of HGF and of MET proto-oncogene (c-MET). Western blot analysis confirmed the Q-PCR results and showed that intracellular signaling components (protein kinase B/Akt, ERK1/2, and STAT3) were functional. The TGF-beta1 mRNA levels were unchanged in CPSS whereas there was a 2-fold increase in PPVH indicating an active TGF-beta1 pathway, consistent with the observation of fibrosis seen in PPVH. Western blots on TGF-beta1 and phosphorylated Smad2 confirmed an activated pro-fibrotic pathway in PPVH. Furthermore, Q-PCR showed an increase in the amount of collagen I present in PPVH compared to CPSS and control, which was confirmed by Western blot analysis.


CONCLUSIONS
The pathophysiological differences between CPSS and PPVH can adequately be explained by the Q-PCR measurements and Western blots. Although c-MET levels were reduced, downstream signaling seemed to be functional and provides a rational for HGF-supplementation in controlled studies with CPSS and PPVH. Furthermore both diseases may serve as simplified models for comparison with more complex chronic inflammatory diseases and cirrhosis.
Spee
Bart
B
Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands. b.spee@vet.uu.nl
Penning
Louis C
LC
van den Ingh
Ted S G A M
TS
Arends
Brigitte
B
Ijzer
Jooske
J
van Sluijs
Frederik J
FJ
Rothuizen
Jan
J