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Increased iron deposition in rat liver fibrosis induced by a high-dose injection of dimethylnitrosamine. Exp Mol Pathol 2006; 81:255-61. [PMID: 16979622 DOI: 10.1016/j.yexmp.2006.07.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2006] [Revised: 07/03/2006] [Accepted: 07/26/2006] [Indexed: 02/06/2023]
Abstract
Using a developed rat model of hepatic necrosis and subsequent fibrosis induced by a high-dose intraperitoneal injection of dimethylnitrosamine (DMN), we studied iron deposition and expression of transforming growth factor-beta(1) (TGF-beta(1)) during the development of persistent liver fibrosis. Rats were sacrificed at several timepoints from 6 h to 10 months post-injection and the livers were examined for iron content and distribution, and for expression of alpha-smooth muscle actin, ED-1, TGF-beta(1), and collagen (alpha(2))I. Morphologic evidence of acute submassive hemorrhagic necrosis peaked at 36 h; on day 3 the residual parenchyma contained activated hepatic stellate cells (HSCs) and necrotic areas contained numerous macrophages; and on day 5, necrotic tissues and erythrocytes had been phagocytosed and macrophages contained abundant iron deposits. From days 7 to 10, iron-laden macrophages and activated HSCs (myofibroblasts) populated the fibrous septa in parallel. From week 2 to month 10, closely arranged macrophages and myofibroblasts were found in central-to-central bridging fibrotic tissue. TGF-beta(1) was strongly detected in both macrophages and HSCs during development of liver fibrosis. Our data suggest that increased iron deposition may be involved in the initiation and perpetuation of rat liver fibrosis. Iron-laden macrophages may influence HSCs through the action of TGF-beta(1) in DMN-induced liver fibrosis.
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Center SA. Metabolic, antioxidant, nutraceutical, probiotic, and herbal therapies relating to the management of hepatobiliary disorders. Vet Clin North Am Small Anim Pract 2004; 34:67-172, vi. [PMID: 15032126 DOI: 10.1016/j.cvsm.2003.09.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Many nutraceuticals, conditionally essential nutrients, and botanical extracts have been proposed as useful in the management of liver disease. The most studied of these are addressed in terms of proposed mechanisms of action, benefits, hazards, and safe dosing recommendations allowed by current information. While this is an area of soft science, it is important to keep an open and tolerant mind, considering that many major treatment discoveries were in fact serendipitous accidents.
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Affiliation(s)
- Sharon A Center
- College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
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Abstract
Iron is an essential micronutrient. However, because human beings have no means to control iron excretion, excess iron, regardless of the route of entry, accumulates in parenchymal organs and threatens cell viability. Indeed, when iron-buffering capability is overwhelmed, oxidative stress-induced cell damage and fibrogenesis may arise, mainly in the liver, the main storage site for iron in the body. Results of recent studies have clearly shown that these pathologic events are induced by iron-generated reactive oxygen species and lipid peroxidation by-products. Hepatic fibrosis, characterized by excessive accumulation of extracellular matrix components in the liver, is a dynamic process, from chronic liver damage to end-stage liver cirrhosis. Iron-induced oxidant stress is involved in this process (1) as the primary cause of parenchymal cell necrosis or (2) as activator of cells that are effectors [e.g., hepatic stellate cells, (myo)fibroblasts] or key mediators (e.g., Kupffer cells) of hepatic fibrogenesis (or through both mechanisms). Beyond their effect as direct cytotoxic agents, iron and free radicals may trigger increased synthesis of collagen in myofibroblast-like cells as well as activate granulocytes and Kupffer cells, resulting in an increased formation of cytokines and eicosanoids and further reactive oxygen species. This may constitute a cascade of amplifying loops, which perpetuate the fibrogenic process. The fibrogenic potential of iron is even more dramatic when iron acts in concert with other hepatotoxins such as alcohol. In this instance, even if tissue iron levels are only slightly elevated, the toxic effect of alcohol or its metabolites may be amplified and propagated with rapid acceleration of the liver disease. At the molecular level, the presence of catalytically active "free iron" may (1) contribute directly to the hepatotoxicity of alcohol or (2) enhance the generation of cytokine and fibrogenic mediators from resident Kupffer cells (or be involved in both ways). A challenge for future research is to develop therapeutic tools able to block "redox-active" free iron in the cell.
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Affiliation(s)
- Antonello Pietrangelo
- Centre for the Study of Iron Disorders, Department of Internal Medicine, University of Modena and Reggio Emilia, Policlinico, Via del Pozzo 71, 41100 Modena, Italy.
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Hershko C, Link G, Konijn AM, Huerta M, Rosenmann E, Reinus C. The iron-loaded gerbil model revisited: effects of deferoxamine and deferiprone treatment. THE JOURNAL OF LABORATORY AND CLINICAL MEDICINE 2002; 139:50-8. [PMID: 11873245 DOI: 10.1067/mlc.2002.120364] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although the beneficial effects of deferoxamine (DFO) on iron-associated morbidity and mortality are well documented, the role of deferiprone (L1) in the management of transfusional iron overload is controversial. This debate involves not only the question of efficacy but also of safety, with particular emphasis on the risk of a paradoxical aggravation of iron toxicity by L1. We used the iron-loaded gerbil model introduced by Carthew et al to compare the chelating efficacy of L1, DFO, or both in two gerbil strains treated by means of weekly iron-dextran injections: Psammomys obesus and pathogen-free Mongolian gerbils (Meriones unguiculatus). The difference between the high mortality and advanced hepatocellular necrosis observed in iron-loaded P obesus and the absence of mortality and limited morbidity encountered in pathogen-free Mongolian gerbils is most likely explained by the prevention of coincidental laboratory infections in the latter group. Iron-chelating treatment in all experimental groups resulted in a significant decrease in hepatic iron concentrations and normalization of mitochondrial respiratory enzyme activities, with combined L1 and DFO treatment being the most efficient, followed, in decreasing order, by DFO and L1 as single-drug treatments. Judged by tissue iron concentrations, mitochondrial enzyme activity, and hepatic histology, we could find no evidence of a paradoxical aggravation of iron toxicity by L1 in either of the two series of studies. Although these data appear to be reassuring, the present controversy related to the role of L1 in the development of hepatic cirrhosis should be eventually settled by clinical studies evaluating the effects of long-term iron-chelating treatment.
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Affiliation(s)
- C Hershko
- Department of Medicine, Shaare Zedek Medical Center, Jerusalem, Israel
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Lecour S, Maupoil V, Siri O, Tabard A, Rochette L. Electron spin resonance detection of nitric oxide generation in major organs from LPS-treated rats. J Cardiovasc Pharmacol 1999; 33:78-85. [PMID: 9890400 DOI: 10.1097/00005344-199901000-00012] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The increased production of nitric oxide (NO) has been implicated as the basis for myocardial dysfunction and the lack of response to vasoconstrictors during endotoxin shock induced by lipopolysaccharide (LPS). Our objective was to evaluate and compare NO production in major organs of rats treated with LPS, 1 or 14 mg/kg. A NO spin-trapping technique using electron spin resonance (ESR) spectroscopy has been used to study NO production in the liver, the kidney, the aorta, and the heart. The method was based on the trapping of NO by a metal-chelator complex consisting of N-methyl-D-glucamine dithiocarbamate (MGD) and reduced iron (Fe2+) to form a stable [(MGD)2-Fe2+-NO] complex, giving rise to a characteristic triplet ESR spectrum with g = 2.04 and aN = 12.65 G: Iron was quantified in the different organs to study the [(MGD)2-Fe2+] complex distribution. Six hours after intravenous injection of 1 or 14 mg/kg of LPS, we observed large increases in the [(MGD)2-Fe2+-NO] adduct signal in the liver, the kidney, and in the aorta, strongly suggesting an increased production of NO in these organs. The [(MGD)2-Fe2+-NO] adduct was also detected in the heart, 6 h after injection of LPS. Moreover, we observed dose-dependent increases in [(MGD)2-Fe2+-NO] adduct in the heart, whereas no changes were observed in the other organs. Concurrently, the [(MGD)2-Fe2+-NO] adduct was not detected in the blood from rats treated with LPS, although circulating nitrosylhemoglobin, nitrite, and nitrate levels increased. The spin-trapping technique allowed us to monitor organ-specific formation of NO after LPS administration and for the first time demonstrated direct NO production in aorta and heart of LPS-treated animals.
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Affiliation(s)
- S Lecour
- Laboratoire de Physiopathologie et Pharmacologie Cardiovasculaires Expérimentales, Facultés de Médecine et Pharmacie, Dijon, France
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Affiliation(s)
- A Pietrangelo
- Department of Internal Medicine, University of Modena, Italy
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Chamulitrat W, Carnal J, Reed NM, Spitzer JJ. In vivo endotoxin enhances biliary ethanol-dependent free radical generation. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 274:G653-61. [PMID: 9575846 DOI: 10.1152/ajpgi.1998.274.4.g653] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Endotoxemia is associated with alcoholic liver diseases; however, the effect of endotoxin on the oxidation of ethanol is not known. We tested the hypothesis that endotoxin treatment enhances hepatic ethanol radical production. The generation of free radicals by the liver was studied with spin-trapping technique utilizing the primary trap ethanol (0.8 g/kg) and the secondary trap alpha-(4-pyridyl-1-oxide)-N-t-butylnitrone (4-POBN; 500 mg/kg). Electron paramagnetic resonance (EPR) spectra of bile showed six-line signals, which were dependent on ethanol, indicating the trapping of ethanol-dependent radicals. Intravenous injections of Escherichia coli lipopolysaccharide (0.5 mg/kg) 0.5 h before 4-POBN plus ethanol treatment caused threefold increases of biliary radical adducts. EPR analyses of bile from [1-13C]ethanol-treated endotoxic rats showed the presence of species attributable to alpha-hydroxyethyl adduct, carbon-centered adducts, and ascorbate radical. The generation of endotoxin-induced increases of ethanol-dependent radicals was suppressed by 50% on GdCl3 (20 mg/kg i.v.) or desferrioxamine mesylate (1 g/kg i.p.) treatment. Our data show that in vivo endotoxin increases biliary ethanol-dependent free radical formation and that these processes are modulated by Kupffer cell activation and catalytic metals.
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Affiliation(s)
- W Chamulitrat
- Department of Physiology, Louisiana State University Medical Center, New Orleans 70112-1393, USA
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Affiliation(s)
- S L Friedman
- University of California, Liver Center Laboratory, San Francisco General Hospital, USA
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Pietrangelo A, Gualdi R, Casalgrandi G, Montosi G, Ventura E. Molecular and cellular aspects of iron-induced hepatic cirrhosis in rodents. J Clin Invest 1995; 95:1824-31. [PMID: 7706489 PMCID: PMC295717 DOI: 10.1172/jci117861] [Citation(s) in RCA: 103] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Hepatic fibrosis and cirrhosis are common findings in humans with hemochromatosis. In this study we investigated the molecular pathways of iron-induced hepatic fibrosis and evaluated the anti-fibrogenic effect of vitamin E. Male gerbils were treated with iron-dextran and fed a standard diet or a alpha-tocopherol enriched diet (250 mg/Kg diet). In gerbils on the standard diet at 6 wk after dosing with iron, in situ hybridization analysis documented a dramatic increase of signal for collagen mRNA around iron foci onto liver fat storing cells (FSC), as identified by immunocytochemistry with desmin antibody. After 4 mo, micronodular cirrhosis developed in these animals, with nonparenchymal cells surrounding hepatocyte nodules and expressing high level of TGF beta mRNA. In this group, in vivo labeling with [3H]-thymidine showed a marked proliferation of nonparenchymal cells, including FSC. In iron-dosed gerbils on the vitamin E-enriched diet for 4 mo, in spite of a severe liver iron burden, a normal lobular architecture was found, with a dramatic decrease of collagen mRNA accumulation and collagen deposition. At the molecular level, a total suppression of nonparenchymal cell proliferation was appreciable, although expression of collagen and TGF beta mRNAs was still present into microscopic iron-filled nonparenchymal cell aggregates scattered throughout the hepatic lobule. In conclusion, our study shows that anti-oxidant treatment during experimental hepatic fibrosis arrests fibrogenesis and completely prevents iron induced hepatic cirrhosis mainly through inhibition of nonparenchymal cell proliferation induced by iron.
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Affiliation(s)
- A Pietrangelo
- Department of Internal Medicine, University of Modena, Italy
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Carthew P, Smith AG. Pathological mechanisms of hepatic tumour formation in rats exposed chronically to dietary hexachlorobenzene. J Appl Toxicol 1994; 14:447-52. [PMID: 7884150 DOI: 10.1002/jat.2550140610] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The chronic dietary administration of hexachlorobenzene (HCB) to rats for a year or more results in the formation of liver tumours described as hepatocellular carcinomas, hepatomas or haemangiomas. The hepatotoxicity of HCB, which is greatest in hamsters and rats, gives rise to peliosis and necrosis with haemosiderosis. This pattern of hepatotoxicity indicates vascular damage, which through haemosiderosis could increase not only the toxic effect of HCB to hepatocytes but also its tumourogenic potential. The present study confirmed vascular damage by the identification of widespread fibrin deposits in the livers of rats chronically exposed to HCB, using an antibody to rat fibrin. Based on our study we suggest that the formation of hepatomas and haemangiomas with elements of peliosis (cystic blood-filled cavities) could be explained by the compensatory hyperplastic responses to hepatocellular necrosis and by the simultaneous loss of hepatocellular cords. The accumulation of iron in the liver would strongly potentiate the development of hepatic tumours, as has been found in HCB and polychlorinated biphenyl-treated mice with iron overload. The implications of this non-genotoxic mechanism of hepatoma formation for the assessment of human health risk are discussed.
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Affiliation(s)
- P Carthew
- MRC Toxicology Unit, University of Leicester, UK
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Abstract
Two 2-year-old Salers cattle from different herds raised on pasture were evaluated for retarded growth and diarrhea. Increase of liver enzyme activities and prolonged sulfobromophothalein (BSP) half life (T1/2) indicated liver disease with impaired liver function. Histopathologic examination of liver biopsies revealed a micronodular cirrhosis with marked deposition of hemosiderin in hepatocytes, Kupffer cells, and arterioles. Transferrin saturation (TS) and liver iron content were markedly increased, consistent with a diagnosis of hemochromatosis. Both animals were euthanatized due to deterioration in their condition. Necropsy findings included hepatomegaly and hemosiderin accumulation in the liver, lymph nodes, pancreas, spleen, thyroid, kidney, brain and other glandular tissue. Continued surveillance of the second herd (serum iron, total iron binding capacity [TIBC], unsaturated iron binding capacity [UIBC], and TS), identified a heifer as a hemochromatosis suspect in a subsequent generation. Liver biopsies from that animal revealed the same histopathologic changes as the previous 2 animals, and similar increases in liver iron content (8,700 ppm, normal range 45 to 300 ppm). The 3 affected cattle were all products of line breeding programs and shared a common ancestor. The absence of dietary iron loading in conjunction with the histopathologic and metabolic findings were consistent with a diagnosis of primary hemochromatosis. The reported disease is similar to idiopathic hemochromatosis in human beings in which there is a hereditary defect in iron metabolism.
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Affiliation(s)
- J K House
- Veterinary Medical Teaching Hospital, Large Animal Clinic, School of Veterinary Medicine, University of California, Davis 95616
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Ferrali M, Signorini C, Ciccoli L, Comporti M. Iron released from an erythrocyte lysate by oxidative stress is diffusible and in redox active form. FEBS Lett 1993; 319:40-4. [PMID: 8454059 DOI: 10.1016/0014-5793(93)80033-q] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The incubation of a ghost-free erythrocyte lysate with the oxidizing agent phenylhydrazine resulted in both methemoglobin formation and release of iron in a desferrioxamine (DFO)-chelatable form. The released iron was diffusible, as shown by a dialysis carried out simultaneously with the incubation. When the dialysate was added to erythrocyte ghosts or to microsomes from liver or brain, lipid peroxidation developed in the membranes, indicating that the diffusible iron was in a redox active form. The addition of ATP to the lysate markedly increased both iron diffusion and lipid peroxidation in the membranes subsequently added to the dialysate. The possible implication of these data in some well known pathologies is discussed.
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Affiliation(s)
- M Ferrali
- Istituto di Patologia Generale, Università di Siena, Italy
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