Expression of osteoactivin in rat and human liver and isolated rat liver cells.
OBJECTIVE
The transmembrane glycoprotein osteoactivin is expressed in osteoblasts, dendritic cells and tumor cells. It is suggested to influence osteoblast maturation, cell adhesion and migration. We studied osteoactivin expression within the liver.


METHODS
Expression of osteoactivin was analysed by RT-PCR, Northern blotting, in situ hybridisation (ISH) and immunohistochemistry (IHC) comparing normal and acutely injured rat liver [induced by carbon tetrachloride (CCl(4)) administration], liver cell populations, and normal or diseased human liver.


RESULTS
By ISH osteoactivin expression was detected in sinusoid-lining cells found by IHC to be positive for the common mononuclear phagocyte marker antibody anti-CD68. While total liver contained only traces, isolated Kupffer cells expressed abundant amounts of osteoactivin mRNA further increasing during culture. In acutely injured rat liver osteoactivin expression was strongly increased reaching maximum of expression 48h after CCl(4). By ISH osteoactivin expression was localised in pericentral inflammatory cells and sinusoid-lining cells again anti-CD68 positive. Dexamethasone and lipopolysaccharide decreased osteoactivin expression in cultured mononuclear phagocytes of normal as well as of acutely injured liver. In human liver osteoactivin was increased in fulminant hepatitis and paracetamol intoxication.


CONCLUSIONS
Osteoactivin is expressed at high levels in normal and inflammatory liver macrophages suggesting a significant role in acute liver injury.
Haralanova-Ilieva
Borislava
B
Department of Gastroenterology and Endocrinology, Georg-August-University Goettingen, Robert-Koch-Str. 40, 37075 Goettingen, Germany.
Ramadori
Giuliano
G
Armbrust
Thomas
T
D000208:Acute Disease; D000818:Animals; D002251:Carbon Tetrachloride; D019070:Cell Lineage; D002478:Cells, Cultured; D056486:Chemical and Drug Induced Liver Injury / Q000276:immunology / Q000503:physiopathology*; D003713:Dendritic Cells / Q000502:physiology; D015870:Gene Expression; D006801:Humans; D007728:Kupffer Cells / Q000502:physiology*; D008099:Liver / Q000166:cytology* / Q000502:physiology*; D008562:Membrane Glycoproteins; D010586:Phagocytes / Q000502:physiology; D011506:Proteins / Q000235:genetics*; D051381:Rats; D017208:Rats, Wistar
C503042:GPNMB protein, human; C503043:Gpnmb protein, rat; D008562:Membrane Glycoproteins; D011506:Proteins; D002251:Carbon Tetrachloride