MECHANISMS OF LIVER REPAIR AFTER BILIARY RECONSTRUCTION

Project: Research project

Description

The broad goal of this research is to establish the physiologic
significance of mitogenic growth factors in liver repair after chronic
injury. This proposal focuses on the potential roles in repair for
transforming growth factors a&B (TGFalpha β), hepatocyte growth
factor (HGF), and Kupffer cell derived tumor necrosis factor alpha
(TNFalpha) which are known to regulate liver regeneration after acute
injury. There are five specific aims. Aim 1: Determine TGFalphaΒ, HGF, and TNFalpha gene expression in the
liver during chronic, cholestatic injury and repair. The simultaneous
expression of protooncogene mRNAs coding for receptors for TGFalpha and
HGF, c-erbB and c-met, will be determined and protein levels will be
measured. Cholestasis will be initiated in rats by vessel loop
suspension of the common bile duct for increasing periods of injury;
release of the loop allows biliary decompression to simulate
reconstruction and initiate repair. mRNA levels will be quantified by
ribonuclease protection assays and protein by Western blots. Aim 2: Localize the cellular sources of HGF and TGF alpha & Beta mRNA and
proteins during repair after chronic injury b a combination of in situ
hybridization and immunohistochemical techniques. Aim 3: Related changes in steady state levels of growth factor and
receptor expression to in vivo hepatocellular DNA synthesis by
immunohistochemistry for proliferating cell nuclear antigen. Important
modulator os the regenerative response will be studied during repair
after Kupffer cell blockade by the injection of gadolinium and after
endotoxin restriction by the administration of Polymyxin B. Aim 4: Examine functional and proliferative changes to in vitro TGFalpha
and HGF stimulation in hepatocytes isolated after increasing periods of
cholestatic injury. Hepatocytes will be extracted and purified by
centrifugal elutriation and in vitro morphology, DNA synthesis, and
albumin synthesis will be measured. Aim 5: Establish the autocrine mechanism(s) of growth factor stimulation
by TGFalpha on normal and injured hepatocytes by measuring DNA synthesis,
the hepatocytes expression of c-erbB and, the levels of TGFalpha mRNA. These studies are designed to test the hypothesis that after acute
injury, liver repair and regeneration share similarities in the growth
factor control of hepatocyte proliferation. However, because
regeneration yields a normal liver, and repair often lead to scar,
quantitative differences in either growth factors and their receptors,
or the hepatocyte response to growth factor stimulation must exist to
slow the course, and inhibit the quality of repair. Data from this
combined in vivo and in vitro approach should provide insights into the
role and mechanism of action of growth factors in chronic liver injury
and repair.
StatusFinished
Effective start/end date5/1/945/31/09

Funding

  • National Institutes of Health
  • National Institutes of Health: $324,110.00
  • National Institutes of Health: $101,247.00
  • National Institutes of Health
  • National Institutes of Health: $90,007.00
  • National Institutes of Health
  • National Institutes of Health: $263,245.00
  • National Institutes of Health: $257,058.00
  • National Institutes of Health: $263,245.00
  • National Institutes of Health: $263,245.00

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Liver
Transforming Growth Factor alpha
Wounds and Injuries
Hepatocytes
Kupffer Cells
Hepatocyte Growth Factor
Matrix Metalloproteinases
Intercellular Signaling Peptides and Proteins
Messenger RNA
Liver Regeneration
Matrix Metalloproteinase Inhibitors
Cicatrix
Growth Factor Receptors
Gadolinium
DNA
Decompression
Tumor Necrosis Factor-alpha
Fibrosis
Macrophages
Proteins