ABSTRACT
BACKGROUND/AIMS: Osteopontin has been implicated in numerous physiopathological events. Osteopontin expression in normal and fibrotic liver and liver fibrogenesis in osteopontin-deficient mice were studied. METHODS: Fibrosis was induced in mice and rats by carbon tetrachloride (CCl4) treatment or bile duct ligation. The liver was used for conventional histology, osteopontin immunohistochemistry and in situ hybridization, or protein and RNA extraction. In mice, necrotic areas and fibrosis were evaluated by quantitative image analysis. RESULTS: In normal liver, osteopontin mRNA expression was very low. After CCl4 treatment or bile duct ligation, osteopontin mRNA expression was increased. Osteopontin was expressed by biliary epithelial cells in normal and fibrotic liver. Soon after the beginning of the CCl4 treatment, osteopontin was also present in inflammatory cells of the necrotic areas. In osteopontin-deficient mice, necrotic areas after a single dose of CCl4, and fibrosis after chronic CCl4 treatment were significantly increased as compared with wild-type treated mice. CONCLUSIONS: Our results show that osteopontin expression increases during liver fibrogenesis. Furthermore, osteopontin-deficient mice were more susceptible to CCl4 treatment, displaying more necrosis during the initial steps (probably due to a deficiency in nitric oxide production) and more fibrosis thereafter. The increase in osteopontin expression observed during liver fibrogenesis may play a protective role.
Subject(s)
Gene Expression , Liver Cirrhosis/metabolism , Liver Regeneration/physiology , RNA, Messenger/genetics , Sialoglycoproteins/genetics , Animals , Blotting, Northern , Carbon Tetrachloride/toxicity , Cytokines/metabolism , Disease Models, Animal , Immunohistochemistry , In Situ Hybridization , Liver Cirrhosis/chemically induced , Liver Cirrhosis/pathology , Male , Mice , Osteopontin , RNA, Messenger/biosynthesis , Rats , Rats, Wistar , Reverse Transcriptase Polymerase Chain Reaction , Sialoglycoproteins/biosynthesis , Sialoglycoproteins/deficiencyABSTRACT
Fibrillin-1, together with elastin, is the main component of elastic fibers found throughout the extracellular space and responsible for the biomechanical properties of most tissues and organs. In this work, fibrillin-1 expression and modulation were explored in experimental rat liver fibrosis and in vitro; furthermore, the role of fibrillin-1 fragments on cell adhesion was analyzed. Fibrosis was induced by subjecting rats to common bile duct ligation for 72 h and 7 days or carbon tetrachloride (CCl(4)) treatment for 2 and 6 weeks. Immunohistochemistry showed that, after bile duct ligation, fibrillin-1, elastin, and alpha-smooth muscle actin colocalized in the developing portal connective tissue. In CCl(4)-treated animals, a similar colocalization was observed in septa; however, elastin deposition was not observed around activated alpha-smooth muscle actin-positive stellate cells of the parenchyma. Treatment with the profibrogenic mediator transforming growth factor-beta1 (TGF-beta1) greatly increased the fibrillin-1 expression of cultured liver fibroblasts. The level of fibrillin-1 expression was significantly higher in cells grown in restrained (stressed) collagen lattices compared with those grown in unrestrained collagen lattices. Cell adhesion on the C-terminal fragment of fibrillin-1 containing the RGD sequence (rF6H) slightly increased (between 0.3 and 2.5 microg/ml) and decreased at higher concentrations, while adhesion on the N-terminal fragment of fibrillin-1 (rF16) was dose-dependently decreased. In addition, the rF16 fragment decreased cell adhesion to fibronectin. In conclusion, our study illustrates the important deposition of fibrillin-1 that occurs in two mechanistically distinct settings of liver fibrogenesis. Furthermore, the induction of fibrillin-1 expression by TGF-beta1 and mechanical stress, and the antiadhesive properties of fibrillin-1 fragments suggest important implications for physiological and pathological fibrillin-1 catabolism during tissue remodeling.
Subject(s)
Fibroblasts/metabolism , Liver Cirrhosis/metabolism , Liver/metabolism , Microfilament Proteins/metabolism , Actins/metabolism , Animals , Cell Adhesion/physiology , Cell Line, Transformed , Collagen , Elastic Tissue , Elastin/metabolism , Fibrillin-1 , Fibrillins , Fibroblasts/drug effects , Fibroblasts/pathology , Humans , Immunoenzyme Techniques , Isometric Contraction , Liver/drug effects , Liver/pathology , Liver Cirrhosis/etiology , Liver Cirrhosis/pathology , Male , Microfibrils/physiology , Rats , Rats, Sprague-Dawley , Stress, Mechanical , Transforming Growth Factor beta/pharmacology , Transforming Growth Factor beta1ABSTRACT
Vinte amostras de carcinoma de células transicionais de bexiga classificadas segundo a OMS quanto ao grau de diferenciaçäo e invasibilidade foram imunomarcados com antilamina (LN); anticitoceratinas 7 (CK7) e 20 (CK20). O aspecto da LN na membrana basal urotelial (MB) foi graduado como 0 - linear e contínua, I - com interrupçöes focais e 2 - ausente. A marcaçäo citoplasmática para LN, CK7 e CK20 foi subjetivamente graduada de 0 - ausente a 3 - intensa. A interrupçäo focal MB foi detectada em um caso de carcinoma de grau 0 (n=2), em um de grau I (n=3), em todas as amostras de grau II (n=I0), enquanto que nos carcinomas de grau III (n=5) näo detectamos LN na MB. A análise de citoceratinas mostrou que o grau de invisibilidade celular dos carcinomas de células transicionais está mais correlacionado à perda de expressäo de CK20. Entretanto, a citoceratina 7 continua sendo expressa mesmo nos tumores de mais alto grau
