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

Hepatic fat-storing cells (FSC) play a key role in the development of fibrosis as a major source of collagen and other extracellular matrix (ECM) proteins in the injured liver. Both experimental and clinical studies have shown that lipid peroxidation is often associated with the development of liver fibrosis. Here we report that exposure of cultured human liver FSC to the pro-oxidant system ascorbate/iron results in an early induction of lipid peroxidation, as monitored in terms of MDA and fluorescent aldehyde/protein adducts production, and in a significant increase of the constitutive expression of procollagen type I mRNA paralleled by the accumulation of the protein in cell culture media. This fibrogenic effect is almost completely abolished by pretreatment of FSC cultures with the antioxidants alpha-tocopherol (Vitamin E) or diphenylphenylendiamine (DPPD). Moreover, treatment of FSC with 1.0 microM 4-hydroxynonenal (HNE), a highly reactive aldehydic end-product of lipid peroxidation, results in a significant stimulation of procollagen type I gene expression and synthesis, suggesting that this aldehyde also exerts profibrogenic activity. These findings indicate that oxidative reactions can directly influence procollagen I gene expression and synthesis in FSC, thus contributing to the development of liver fibrosis.
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PMID:Stimulation of lipid peroxidation or 4-hydroxynonenal treatment increases procollagen alpha 1 (I) gene expression in human liver fat-storing cells. 835 62

Iron overload to the liver induces hepatic injury, eventually ending up with liver fibrosis or cirrhosis. Pathogenic mechanisms involved in liver damage are only partially known, but there is evidence for an important role of iron-induced reactive oxygen species. We have, therefore, analyzed the immunohistochemical reactivity for two major free radical scavengers, copper/zinc and manganese superoxide dismutase (Cu/Zn- and Mn-SOD's) in three situations of hepatic iron overload, and compared enzyme patterns with grades of iron deposition, grades of fibrosis, and levels of microphotometrically measured type IV collagen immunoreactivity. Cu/Zn- and Mn-SOD reactivity was detectable in hepatocytes with a heavy and a low iron burden, but Cu/Zn-SOD staining was more intense than that of Mn-SOD in the three groups analysed. There was trend for microphotometrically measured type IV collagen levels to increase with the amount of iron, and increased collagen IV was correlated with higher grades of Cu/Zn-SOD, but not of Mn-SOD, reactivity. The findings suggest that the two SOD's may be differentially expressed in states of hepatic iron overload, and that low expression of the inducible radical scavenger, Mn-SOD, may play a role in chronic iron toxicity.
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PMID:Copper/zinc and manganese superoxide dismutase immunoreactivity in hepatic iron overload diseases. 857 13

An increasing body of experimental evidence is emerging to incriminate oxidative stress as a pivotal signal for liver fibrogenesis. This paper reviews the results from our studies testing this hypothesis. In the rat model of alcoholic liver disease, the importance of oxidative stress was supported by marked accentuation of liver fibrosis by dietary supplementation of iron, a pro-oxidant, and the significant correlation of the liver malondialdehyde (MDA) and 4-hydroxynonenal (4HNE) levels with the hepatic collagen accumulation. Both MDA and 4HNE adduct epitopes were detected intensely and diffusely in close association with collagen deposition. The direct cause and effect relationship between MDA/4HNE and Ito cell stimulation was indicated by the demonstration of Ito cell collagen gene induction by these aldehydes in culture. In primary cultures of rat Kupffer cells (KC), addition of antioxidants such as alpha-tocopherol acetate and succinate suppressed mRNA expression and the release of interleukin (IL)-6 and tumour necrosis factor alpha (TNF alpha). In rats with biliary fibrosis, an increase in the liver MDA level was accompanied by enhanced mRNA expression of procollagen alpha 1(I) and transforming growth factor beta 1 in Ito cells; and that of TNF alpha and IL-6 in KC. Furthermore, the gel shift assay of KC nuclear extracts showed enhanced NF-kB DNA binding activity. These results support the proposal that enhanced oxidative stress constitutes an important signal for activation of Kupffer and Ito cells in experimental liver fibrogenesis.
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PMID:Roles of oxidative stress in activation of Kupffer and Ito cells in liver fibrogenesis. 858 43

The improvement in survival and quality of life of iron-overloaded patients achieved by regular subcutaneous chelation has been extensively documented over the years. A review of the long-term results allows one to establish the following points: (1) with regular subcutaneous chelation, a negative iron balance can be obtained in most patients, except very young ones; (2) severe deferoxamine (DFO) toxicity may be prevented by skipping high doses and by carefully monitoring and modulating chelation, especially in patients with a low iron overload; (3) the maintenance of compliance with DFO over 0.6 and of ferritin levels below 2,000 prevents iron overloaded complications, at least for the first 20 years of life; (4) long-term chelation can reverse functional complications such as liver fibrosis, arrhythmia and echocardiographic abnormalities, but not complications due to extensive tissue alterations, such as frank diabetes, hypothyroidism and myocardiosclerosis; (5) intensive intravenous protocols can be successfully applied in heavily overloaded patients and represent the only possibility to reverse their dangerous iron burden in a relatively short period of time; (6) survival and quality of life in well-chelated patients are approaching a normal pattern, and (7) clinical outcome and prognosis are better evaluated by parameters that consider iron overload and chelation trends.
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PMID:Results of long-term iron-chelating therapy. 860 84

Ethanol consumption and/or liver damage may alter liver content of several trace elements, as iron, zinc, copper, and manganese. This alteration may play a role on ongoing liver fibrogenesis. Based on these facts we have determined liver, serum, and urinary Mn, Cu, Zn, and Fe levels in a group of alcoholic cirrhotics and noncirrhotics with normal renal function, comparing them with those of controls. We have observed low liver zinc and high liver copper--this last in relation with histomorphometrically determined total amount of liver fibrosis--and manganese contents in cirrhotics, together with increased excretion of zinc and iron and decreased excretion of manganese. Zinc, iron, and copper excretion kept a relation with data of severity of cirrhosis, including mortality in the case of urinary copper, independently of the use of diuretics. Thus, liver copper and urinary iron, zinc, and copper excretion seem to be related with data of severity of chronic alcoholic liver disease. Low urinary manganese excretion may play a role on liver manganese overload.
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PMID:Zinc, copper, manganese, and iron in chronic alcoholic liver disease. 901 22

We report on two sibs with syndromal congenital iron storage disease. Prenatal symptoms were IUGR, hydramnios, and placental hyperplasia. Clinical anomalies included hypertelorism and sparse, thin, curly hair (trichomalacia). Clinical course was marked by intractable diarrhoea, with normal histological and enzymological studies, cholestatic jaundice, hepatomegaly appearing after 30 days, and progressive liver failure, leading to death after a few months. The only metabolic anomaly was progressive hypermethioninemia. Pathologic examination of both children showed a similar pattern of multivisceral iron deposit compatible with a diagnosis of neonatal hemochromatosis: extensive liver fibrosis or cirrhosis with nodular regeneration, cholestasis, ductular proliferation, and hepatic, pituitary, thyroidal, adrenal, and pancreatic iron deposition. The unusual course for neonatal hemochromatosis in both sibs combined with concordant extrahepatic anomalies suggest that they could have a specific iron storage syndrome with possible autosomal recessive inheritance, probably similar to the sibship reported by Stanckler et al. [Arch Dis Child, 57:212-216, 1982].
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PMID:Tricho-hepato-enteric syndrome: further delineation of a distinct syndrome with neonatal hemochromatosis phenotype, intractable diarrhea, and hair anomalies. 902 Oct 8

The pathogenesis of liver fibrosis in genetic haemochromatosis and other iron overload states remains enigmatic. Recent advances in the cellular and molecular pathogenesis of liver fibrosis have determined a central role for hepatic stellate cells. These become activated to a myofibroblastic phenotype following most forms of liver injury and are the major cellular source of collagens and other matrix proteins laid down in fibrotic liver. Similar changes have now been reported in the liver in genetic haemochromatosis, with activation of stellate cells becoming more prominent with increasing hepatic iron concentration. In contrast to other liver diseases, this apparently occurs in the absence of significant necroinflammatory change. Unravelling the mechanism of liver fibrogenesis in iron overload states may, therefore, provide important general insights into the pathogenesis of liver fibrosis. The present article reviews current knowledge of this field with emphasis on the role of lipid peroxidation, sideronecrosis of hepatocytes and spillover of iron to Kupffer cells. An attempt is made to draw these observations together with previous studies of the mechanisms of stellate cell activation in other models and diseases. A unifying hypothesis emerges that helps to define some of the next research questions in the pathogenic mechanisms of liver fibrosis in iron overload.
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PMID:Iron overload and liver fibrosis. 903 31

Oxidative stress is associated with liver fibrosis and with hepatic stellate cell (HSC) activation in vivo. However, it remains controversial whether oxidative stress contributes to HSC activation either directly or through a paracrine stimulation by damaged hepatocytes. A medium containing products released from cells undergoing oxidative stress was obtained after incubation of hepatocytes with (HCM/Fe) or without (HCM) 0.1 mmol/L ferric nitrilotriacetate complex (FeNTA). Exposure of HSC to HCM/Fe for 24 hours significantly increased the number of proliferating HSC compared with HCM and to controls at all dilutions tested. The simultaneous coincubation of HSC with HCM/Fe and desferrioxamine (50 micromol/L) did not reduce the observed increase in cell proliferation, thus excluding a role for eventually contaminating iron in HCM/Fe. HCM/Fe induced also a significant increase in collagen type I accumulation in HSC culture media. To study the cellular mechanism underlying HCM/Fe effects, we evaluated the activity of the Na+/H+ exchanger, which plays a role in regulating HSC proliferation. The incubation of HSC for 24 hours with HCM/Fe significantly increased baseline intracellular pH (pHi) and Na+/H+ exchanger activity, indicating a plausible role of this antiport in mediating cell response. In conclusion, hepatocytes undergoing oxidative stress release factors which are fibrogenic for HSC, thereby, confirming what has been only hypothesized in vivo. In addition, HSC proliferation is associated with changes in the Na+/H+ exchanger activity, thus providing a useful target for the evaluation of inhibitors of this pathway for the treatment of hepatic fibrosis.
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PMID:Fibrogenic effect of oxidative stress on rat hepatic stellate cells. 950 Jul

Oxidant stress plays a key role in hepatic fibrogenesis. This study was undertaken to assess whether, during iron overload-associated liver fibrosis in vivo, oxidant stress occurs in hepatic stellate cells (HSC) during active fibrogenesis. Gerbils were treated with iron-dextran, and, after hepatic fibrosis developed, livers were subjected to various combination of in situ hybridization and immunocytochemistry analyses. In iron-treated animals, no specific accumulation of ferritin protein was found in collagen mRNA-expressing cells. Moreover, the activity of the iron regulatory protein, the main sensor of cellular iron status, was unchanged in HSC from iron-treated animals. Although a significant amount of malondialdehyde-protein adducts was detected in gerbil liver during fibrogenesis, accumulation of these lipid peroxidation by-products was restricted to iron-laden cells adjacent to activated HSC. In cultured gerbil HSC, iron, aldehydes, and other pro-oxidants were able to enhance the expression of an oxidant stress-responsive gene, heme oxygenase (HO), with no change in collagen mRNA accumulation. In keeping with these findings, we found that, in vivo, activation of HO gene was present in iron-filled nonparenchymal cell aggregates, but absent in HSC. In conclusion, the data indicate that during iron overload-associated fibrogenesis, HSC are not directly subjected to oxidant stress, but are likely to be activated by paracrine signals arising in neighboring cells.
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PMID:Hepatic stellate cells are not subjected to oxidant stress during iron-induced fibrogenesis in rodents. 962 Mar 35

Mild to moderate hepatic iron overload is frequent in patients with chronic viral hepatitis (CH). We evaluated the role of hemochromatosis (HFE) gene mutations and other acquired factors in the development of iron overload in these patients. We studied 110 patients with chronic B or C viral hepatitis (31 women, 79 men), including 20 with cirrhosis, and 139 controls. Hepatic iron was evaluated by semiquantitative analysis in all the patients, and hepatic iron concentration (HIC) was determined in 97 of them (26 women, 71 men). C282Y and H63D mutations were sought in all the subjects by a polymerase chain reaction-restriction assay. The frequency of HFE genotypes and alleles did not differ in patients and controls. No relation was detected between hepatic iron stores and HFE gene mutations in women. In men, all C282Y heterozygotes had iron overload, and the H63D mutation was significantly more frequent in patients with more marked hepatic siderosis than in those with mild or no siderosis (P = .0039) and in controls (P = .0008). Heavy alcohol intake and hepatic cirrhosis were also associated with increased hepatic iron stores in the men. In the 71 men in whom HIC was measured, multiple regression analysis showed that this variable was related independently only to alcohol intake and HFE gene mutations. We suggest that in patients with CH, iron accumulates in the liver as the result of an interplay between genetic and acquired factors, and that increased liver iron stores may influence progression toward liver fibrosis.
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PMID:Hepatic iron overload in patients with chronic viral hepatitis: role of HFE gene mutations. 975 49


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