Expression of uncoupling protein-2 in biliary epithelial cells in primary biliary cirrhosis.
OBJECTIVE
Uncoupling proteins are thought to protect cells from oxidative stresses. Because uncoupling protein-2 is expressed in liver and reactive oxygen species are involved in pathogenesis of various liver diseases, this protein may protect liver cells from disease-associated oxidative stress. However, uncoupling protein-2 expression in human liver has not been examined.


METHODS
We investigated hepatic uncoupling protein-2 distribution in various liver diseases including primary biliary cirrhosis, autoimmune hepatitis, chronic viral hepatitis, and histologically normal liver by immunohistochemistry.


RESULTS
Uncoupling protein-2 was expressed in some hepatocytes, however, the degree of hepatocytic uncoupling protein-2 expression did not differ significantly among liver diseases and normal liver. Uncoupling protein-2 was abundant in biliary epithelial cells in primary biliary cirrhosis but not in other liver specimens. Enhanced uncoupling protein-2 expression in biliary epithelial cells was specific for primary biliary cirrhosis and did not result simply from cholestasis. The percentage of uncoupling protein-2 positive bile ducts in primary biliary cirrhosis patients treated with ursodeoxycholic acid was significantly lower than in untreated patients.


CONCLUSIONS
These results suggest that uncoupling protein-2 is involved in the pathogenesis of primary biliary cirrhosis.
Taniguchi
Eitaro
E
Second Department of Medicine and Kurume University Research Center for Innovative Cancer Therapy, Kurume University School of Medicine, Japan. eitaro@med.kurume-u.ac.jp
Harada
Masaru
M
Kawaguchi
Takumi
T
Koga
Hironori
H
Kumemura
Hiroto
H
Hanada
Shinichiro
S
Shishido
Shoichiro
S
Baba
Shinji
S
Kumashiro
Ryukichi
R
Ueno
Takato
T
Sakisaka
Shotaro
S
Sata
Michio
M
D001652:Bile Ducts / Q000378:metabolism / Q000473:pathology; D004848:Epithelium / Q000378:metabolism / Q000473:pathology; D019693:Hepatitis, Autoimmune / Q000378:metabolism / Q000473:pathology; D006525:Hepatitis, Viral, Human / Q000378:metabolism / Q000473:pathology; D022781:Hepatocytes / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007124:Immunoenzyme Techniques; D007473:Ion Channels; D008099:Liver / Q000378:metabolism / Q000473:pathology; D008105:Liver Cirrhosis, Biliary / Q000378:metabolism* / Q000473:pathology; D026901:Membrane Transport Proteins; D024101:Mitochondrial Proteins; D014176:Protein Biosynthesis; D014475:Uncoupling Agents; D000071246:Uncoupling Protein 2
D007473:Ion Channels; D026901:Membrane Transport Proteins; D024101:Mitochondrial Proteins; C000604389:UCP2 protein, human; D014475:Uncoupling Agents; D000071246:Uncoupling Protein 2