Phenotypic modulation in lipocytes in experimental liver fibrosis.
The presence of a-smooth muscle actin (smA)-positive cells has recently been reported in the fibrotic liver. Lipocytes have been considered to play important roles in hepatic fibrosis. However, the relation of the a-smA-positive cells and lipocytes has not been determined. The biological implication of a-smA expression remains unknown. To study these questions, we carried out double immunofluorescent staining of a-smA and desmin (a marker for lipocytes), or a-smA and collagen, and double immunohistochemical staining of a-smA and 5-bromo-2'-deoxyuridine (BrdUrd) in carbon tetrachloride-induced fibrotic rat livers. In normal and control livers, a-smA-positive cells were not seen in the lobules, whereas scattered desmin-positive cells were present. With the development of hepatic fibrosis, a-smA was expressed only in a portion of desmin-positive cells located predominantly around collagen bundles. A number of a-smA-positive cells in the lobules were labelled with BrdUrd. These results suggest phenotypic modulation in lipocytes and differentiation of lipocytes towards myofibroblast-like cells, since a-smA is expressed with desmin in myofibroblasts in scar tissue. The expression of a-smA may be related to events of the fibrotic process, such as tissue contraction or fibrogenesis per se.
Tanaka
Y
Y
Second Department of Internal Medicine, Tokyo Medical and Dental University, Japan.
Nouchi
T
T
Yamane
M
M
Irie
T
T
Miyakawa
H
H
Sato
C
C
Marumo
F
F
D000199:Actins / Q000378:metabolism; D000818:Animals; D001973:Bromodeoxyuridine / Q000378:metabolism; D003094:Collagen / Q000378:metabolism; D003893:Desmin / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D007150:Immunohistochemistry; D008099:Liver / Q000378:metabolism* / Q000473:pathology; D008106:Liver Cirrhosis, Experimental / Q000378:metabolism* / Q000473:pathology; D008297:Male; D010641:Phenotype; D051381:Rats; D011919:Rats, Inbred Strains
D000199:Actins; D003893:Desmin; D003094:Collagen; D001973:Bromodeoxyuridine