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Query: UMLS:C0239946 (liver fibrosis)
 8,268 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

While Ito cells appear to be a major source of increased matrix synthesis during hepatic fibrogenesis, the cellular changes that occur in these cells during liver fibrosis have not been well delineated. In this study we examined Ito cell gene expression in isolated cells from normal rats, and rats with carbon tetrachloride-induced fibrosis, in order to better define the changes occurring in these cells during this pathologic process. Specifically, we addressed three questions: (1) which matrix genes are over expressed in Ito cells in fibrotic liver; (2) do these cells increase their expression of the fibrogenic cytokine transforming growth factor-beta 1 (TGF-beta 1); and (3) do Ito cells change their phenotype during hepatic fibrogenesis as reflected by alterations in the expression of their intermediate filament genes? Northern hybridization analysis revealed that Ito cells isolated from fibrotic livers had significant increases in mRNA levels of types I, III and IV procollagen compared to normal cells, while no increases were found in hepatocytes, and Kupffer/endothelial cells had only an increase in type I procollagen mRNA. Analysis of other matrix proteins which increase during hepatic fibrogenesis revealed elevations in laminin B and fibronectin mRNA levels only in Ito cells. Increased Ito cell matrix gene expression was also associated with a 4-fold increase in TGF-beta 1 levels in these cells. No increase in TGF-beta 1 mRNA was found in hepatocytes, and less than a 2-fold increase was found in Kupffer/endothelial cells isolated from fibrotic livers.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The effects of hepatic fibrosis on Ito cell gene expression. 156 Jul 88

The cellular distribution and temporal expression of transcripts from transforming growth factor-beta 1 (TGF-beta 1) and procollagen alpha 1(I), alpha 1(III), and alpha 1(IV) genes were studied in carbon tetrachloride (CCl4)-induced rat liver fibrosis by using in situ hybridization technique. During the fibrotic process, TGF-beta 1 and procollagen genes were similarly and predominantly expressed in Desmin-positive perisinusoidal cells (e.g., fat-storing cells and myofibroblasts) and fibroblasts and their expression continued to be higher than those observed in control rats. These transcripts were also observed in inflammatory cells mainly granulocytes and macrophage-like cells at the early stages of liver fibrosis. The production of extracellular matrix along small blood vessels and fibrous septa coincided with the expression of these genes. Expression of TGF-beta 1 and procollagen genes were not detected in hepatocytes throughout the experiment. No significant differences in cellular distribution or time course of gene expression among procollagen alpha 1(I), alpha 1(III), and alpha 1(IV) were observed. Desmin-positive perisinusoidal cells and fibroblasts appeared to play the principal role in synthesis of collagens in CCl4-induced hepatic fibrosis. The simultaneous expression of TGF-beta 1 and procollagen genes in mesenchymal cells, including Desmin-positive perisinusoidal cells, during hepatic fibrosis suggests the possibility that TGF-beta 1 may have an important role in the production of fibrosis.
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PMID:Cellular distribution of transforming growth factor-beta 1 and procollagen types I, III, and IV transcripts in carbon tetrachloride-induced rat liver fibrosis. 169 77

Activated liver fat-storing cells (FSC) are known to play a key role in the development of liver fibrosis. An important element in FSC activation process is the increased expression of receptors for platelet-derived growth factor (PDGF), a potent mitogen for FSC. The aim of the present study was to evaluate the expression PDGF-receptor alpha and beta subunits in cultured human FSC and their regulation induced by transforming growth factor-beta 1 (TGF-beta), a cytokine potentially involved in an autocrine loop. TGF-beta induced a significant increase of the mitogenic effect of PDGF-BB and did not affect the mitogenicity of PDGF-AA and PDGF-AB, suggesting a selective action of the PDGF-receptor-beta subunit. This hypothesis was confirmed by regulation experiments showing selective and time-dependent upregulation of the messenger (m)RNA encoding for the PDGF-receptor-beta subunit and the relative protein induced by TGF-beta. In addition, binding studies showed a parallel increase of PDGF-BB binding sites after incubation of human FSC with TGF-beta. These studies provide evidence for an additional mechanism leading to the perpetuation of FSC activation and proliferation and contribute to a better understanding of the role of TGF-beta and PDGF in the development of liver fibrosis.
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PMID:Transforming growth factor-beta 1 regulates platelet-derived growth factor receptor beta subunit in human liver fat-storing cells. 780 59

Ito cells (fat-storing cells) have been implicated in mechanisms of liver fibrosis, and transforming growth factor-beta 1 is a key factor that stimulates collagen production by Ito cells. Moreover, Ito cells are reported to possess contractile proteins and to contract with ligands. We recently reported the presence of L-type voltage-operated Ca2+ channels in Kupffer cells. In this study, we examined whether Ito cells contain Ca2+ channels and also evaluated the effect of transforming growth factor-beta 1 on Ca2+ channels. Cytosolic free calcium concentration was measured in individual cultured Ito cells with the fluorescent Ca2+ indicator dye fura-2. Partial replacement of extracellular Na+ with K+ caused an increase in cytosolic free calcium, presumably as a result of transmembrane Ca2+ influx. Basal cytosolic free calcium levels were around 40 to 50 nmol/L in both control and transforming growth factor-beta 1-treated cells. In transforming growth factor-beta 1-treated cells, cytosolic free calcium increased in response to K+ at values as low as 10 mmol/L, whereas untreated cells did not respond. Half-maximal increases in cytosolic free calcium in transforming growth factor-beta 1-treated cells were observed with 63 +/- 6 mmol/L K+. With 100 mmol/L K+, intracellular free calcium increased around fourfold above basal values in transforming growth factor-beta 1-treated cells but was only increased about twofold in untreated controls. We conclude that this increase in cytosolic free calcium occurs by way of voltage-operated calcium channels; it did not occur in the absence of extracellular calcium and cannot be explained by Na+/Ca2+ exchange mechanisms.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Hepatic Ito cells contain calcium channels: increases with transforming growth factor-beta 1. 792 2

In the intragastric ethanol infusion model using a high fat diet (25% calories as corn oil) and adult Wistar rats, focal centrilobular liver necrosis is evident after five weeks of feeding, and liver fibrogenesis is induced between the 9th and 16th weeks. At the 16th week, fibroproliferative activation of Ito cells, a perisinusoidal cell type believed to be a key player in liver fibrogenesis, can be demonstrated by increased DNA synthesis, enhanced gene expression of collagen, and transforming growth factor-beta 1 (TGF beta 1) by these cells. This stage of alcoholic liver fibrogenesis, but not the earlier stage of liver necrosis, is closely associated with enhanced hepatic lipid peroxidation (LP) as demonstrated by significant correlation between the degree of liver fibrosis and hepatic levels of LP aldehydic products such as malondialdehyde (MDA) and 4-hydroxynonenal (4HNE). The direct role of these aldehydes in alcoholic liver fibrogenesis is supported by in vitro demonstration of stimulation of Ito cell collagen gene expression by MDA and 4HNE as well as in vivo confirmation of the importance of the aldehydes in iron-catalyzed potentiation of alcoholic liver fibrogenesis. Induced cytochrome P4502E1 is considered as a primary site of enhanced oxidative stress, and compromised glutathione homeostasis is suggested to underlie, in part, the net increase in hepatic LP. These findings are in support of our working hypothesis that enhanced LP is a critical pathogenetic event for alcoholic liver fibrogenesis.
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PMID:Oxidative stress, antioxidants, and alcoholic liver fibrogenesis. 812 1

Undulin and fibronectin (FN) are large extracellular matrix (ECM) glycoproteins possibly involved in cell-matrix interactions. In this study we analyzed the effect of acetaldehyde and transforming growth factor-beta 1 (TGF-beta 1) on undulin and FN synthesis in cultured fat-storing cells (FSC) isolated from wedge sections of normal human livers. Cultured human FSC expressed two mRNA transcripts (6.5 and 8.5 kb) specific for undulin. Acetaldehyde inhibited both undulin mRNA and protein expression, whereas it had an opposite (stimulatory) effect on FN synthesis. TGF-beta 1 induced a dose-dependent increase of both undulin and FN synthesis in FSC cultures. Furthermore, TGF-beta 1 antagonized the inhibitory effect of acetaldehyde on undulin production and potentiated the stimulatory effect of acetaldehyde on FN synthesis. Since undulin is involved in the supramolecular organization of fibrillar collagens and in their enzymatic degradation, its acetaldehyde-induced inhibition may contribute to ECM rearrangement in the early stages of alcoholic liver fibrosis.
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PMID:Regulation of undulin synthesis and gene expression in human fat-storing cells by acetaldehyde and transforming growth factor-beta 1: comparison with fibronectin. 813 74

Expression of the proteoglycans biglycan and decorin and of transforming growth factor-beta 1 at various stages of liver fibrosis induced experimentally in rats by oral administration of thioacetamide was examined. Using in situ hybridization combined with immunocytochemical staining for cell-type characteristic markers, we demonstrate spatial and temporal expression patterns specific for each of the genes. Biglycan gene expression levels coincided tightly with the activity and extent of fibrosis, fat-storing cells and their transformed form, the myofibroblast-like cells, being the major contributors. Decorin messenger RNA was detectable only after the transition to the chronic inflammatory stage in nonparenchymal cells of periportal fields and, transiently, in the forming septa. In the cirrhotic stage, expression was detected solely in periportal fields with enhanced bile duct proliferation. Transforming growth factor-beta 1 expression was undetectable in normal liver. During the subacute inflammatory stage, a hepatocyte subpopulation expressing low levels of transforming growth factor-beta 1 occurred at the limiting plate. With the progression of fibrosis, transforming growth factor-beta 1 expression levels increased considerably but remained restricted to the mesenchymal cells of the fibrotic septa.
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PMID:Spatial and temporal patterns of gene expression for the proteoglycans biglycan and decorin and for transforming growth factor-beta 1 revealed by in situ hybridization during experimentally induced liver fibrosis in the rat. 835 99

Transforming growth factor-beta 1 is an important cytokine in the pathophysiology of liver fibrosis, stimulating the production of extracellular matrix. Whether this cytokine can also control the degradation of matrix proteins in liver cells has not been investigated. Because plasmin is an important protease for the degradation of matrix glycoproteins, we investigated whether sinusoidal endothelial liver cells could contribute to fibrosing liver disease through the modulation of plasmin-generating enzymes in response to transforming growth factor-beta 1. Sinusoidal endothelial cells from guinea pig liver were investigated in pure monolayer culture. Using 125I-labelled transforming growth factor-beta, we demonstrated high-affinity binding sites on sinusoidal endothelial cells at a density of 9.3 x 10(2) per cell, and a dissociation constant of about 5.5 x 10(-11) mol/L. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed the known three classes of membrane receptors for transforming growth factor-beta. Using biosynthetic labeling of proteins with 35S-methionine, immunoprecipitation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, we showed that sinusoidal endothelial cells produce and secrete plasminogen activator inhibitor type 1 from the beginning of culture. Treatment of confluent cell cultures for 24 hr with transforming growth factor-beta 1 increased synthesis and release of plasminogen activator inhibitor type 1. The response was almost maximal at a concentration of 1 ng transforming growth factor-beta/ml and paralleled the increased synthesis of fibronectin. On reverse fibrin autography we proved that transforming growth factor-beta 1 stimulated the release of functionally active plasminogen activator inhibitor type 1.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Contribution of sinusoidal endothelial liver cells to liver fibrosis: expression of transforming growth factor-beta 1 receptors and modulation of plasmin-generating enzymes by transforming growth factor-beta 1. 840 70

The role of the anti-inflammatory cytokine interleukin-10 (IL-10) was investigated in the mouse model of liver injury induced by carbon tetrachloride (CCl4). To address the role of endogenous IL-10 production, acute hepatitis was induced by CCl4 in C57Bl/6 IL-10 gene knock out (KO) and wild-type (WT) mice. After CCl4 challenge, serum and liver levels of tumor necrosis factor-alpha (TNF-) and serum levels of transforming growth factor-beta 1 (TGF-beta1) increased and were significantly higher in IL-10 KO mice, whereas IL-6 serum levels were only slightly increased compared with WT mice. At histological examination, the livers disclosed a significantly more prominent neutrophilic infiltration in IL-10 KO mice 12 and 24 hours after CCl4 injection. In contrast, hepatocyte necrosis, evaluated by histological examination and serum alanine aminotransferase levels, was only marginally affected. The proliferative response of hepatocytes, assessed by the proliferating cell nuclear-antigen labeling index, was significantly increased in IL-10 KO mice, compared with WT mice 48 hours after CCl4 injection. Finally, repeated CCl4 injections led to more liver fibrosis in IL-10 KO mice after 7 weeks. In conclusion, endogenous IL-10 marginally affects the hepatocyte necrosis although it controls the acute inflammatory burst induced by CCl4. During liver repair, it limits the proliferative response of hepatocytes and the development of fibrosis.
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PMID:Interleukin-10 controls neutrophilic infiltration, hepatocyte proliferation, and liver fibrosis induced by carbon tetrachloride in mice. 982 39

The renin-angiotensin system has been shown to contribute to fibrogenesis in varieties of organs, including the liver. Here, we investigated whether the angiotensin II type 1A receptor (AT1A) is implicated in the development of liver fibrosis, using AT1A-deficient and wild-type (WT) mice. After single dose of carbon tetrachloride (CCl(4)), there were no significant differences between two groups with regard to hepatic inflammation and necrosis. After 4 weeks of treatment with CCl(4), histological examination revealed that AT1A-deficient mice showed less infiltration of inflammatory cells and less severe progression of liver fibrosis compared with WT mice. These findings were accompanied by the hepatic content of hydoxyproline and the expression of alpha-smooth muscle actin (alpha SMA). The level of transforming growth factor-beta 1 (TGF-beta 1) messenger RNA was markedly higher in WT mice when compared with AT1A-deficient mice. These results confirm that signaling via AT1A plays a pivotal role in hepatic fibrogenesis.
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PMID:AT1A-deficient mice show less severe progression of liver fibrosis induced by CCl(4). 1289 Apr 98


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