Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.24.3 (collagenase)
 18,340 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mechanisms responsible for the increased hepatic collagen deposition in alcoholic cirrhosis remain unknown. The question of whether ethanol or acetaldehyde has a direct effect on collagen and noncollagen protein production was investigated in human fibroblasts with no detectable activity of alcohol dehydrogenase to distinguish the effects of these metabolites. To eliminate environmental factors, protein production by confluent human skin, fetal and hepatic fibroblasts was studied after three passages. Cells were labeled with [5-3H]proline for 4 hr in the presence of 0.2 mM ascorbate alone or with addition of either ethanol (50 mM) or acetaldehyde (0 to 300 microM). Rates of protein production were calculated from the radioactivities of collagenase-sensitive and collagenase-resistant proteins. Skin fibroblasts from alcoholic individual either with cirrhosis or without liver disease have comparable rates of collagen and noncollagen protein production. Acetaldehyde, in a concentration found in the liver during ethanol abuse, significantly increased collagen production by human skin fibroblasts (up to 140%), fetal fibroblasts (up to 240%) and hepatic fibroblasts (up to 70%) but the addition of ethanol had no significant effect on basal collagen production. The effect of acetaldehyde was dose-related and affected noncollagen protein production in a similar manner. Acetaldehyde did not cause changes in either proline transport or the specific activity of the proline precursor pool. This newly recognized stimulation of collagen production by acetaldehyde may be a possible mechanism of fibrogenesis in alcoholic individuals.
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PMID:Acetaldehyde stimulates collagen and noncollagen protein production by human fibroblasts. 647 53

To study the molecular structure of Mallory body (MB) proteins we applied infrared spectroscopy of the isolated MBs from livers obtained from autopsied patients with alcoholic cirrhosis and griseofulvin-fed (GF-fed) mice. Liver frozen sections were extracted with detergent and digested with deoxyribo- and ribonuclease and collagenase. MB-enriched fractions were then separated out using the aqueous two-phase polymer system. Immunohistochemical and electron microscopic examination showed that the MB composition was virtually identical in human and mouse livers. Infrared spectra of both MB samples showed that the MBs had more numerous and stronger intermolecular hydrogen bonding than did the background control fractions as well as the cytoskeletal fraction from control and GF-fed mice. This may explain why the proteins in MBs are aggregated. The relative amount of beta-sheets was increased compared to the alpha-helices in the MBs, indicating that conformational changes in the cytokeratin peptides of the MBs had occurred. This may explain why the antigenic sites observed in MB proteins show changes in affinity for antibodies to cytokeratins as observed by immunohistochemical staining of MBs.
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PMID:Molecular structural changes in Mallory body proteins in human and mouse livers: an infrared spectroscopy study. 813 2

Three decades of research in ethanol metabolism have established that alcohol is hepatotoxic not only because of secondary malnutrition, but also through metabolic disturbances associated with the oxidation of ethanol. Some of these alterations are due to redox changes produced by the NADH generated via the liver ADH pathway, which in turn affects the metabolism of lipids, carbohydrates, proteins, and purines. Exaggeration of the redox change by the relative hypoxia, which prevails physiologically in the perivenular zone, contributes to the exacerbation of the ethanol-induced lesions in zone III. Gastric ADH also explains first-pass metabolism by ethanol; its activity is low in alcoholics and in females and is decreased by some H2 blockers. In addition to ADH, ethanol can be oxidized by liver microsomes: studies over the last 20 years have culminated in the molecular elucidation of the ethanol-inducible cytochrome P450 (P4502E1) which contributes not only to ethanol metabolism and tolerance, but also to the selective hepatic perivenular toxicity of various xenobiotics. Their activation by P4502E1 now provides an understanding for the increased susceptibility of the heavy drinker to the toxicity of industrial solvents, anesthetic agents, commonly prescribed drugs, over-the-counter analgesics, chemical carcinogens, and even nutritional factors such as vitamin A. Ethanol causes not only vitamin A depletion, but it also enhances its hepatotoxicity. Furthermore, induction of the microsomal pathway contributes to increased acetaldehyde generation, with formation of protein adducts, resulting in antibody production, enzyme inactivation, decreased DNA repair; it is also associated with a striking impairment of the capacity of the liver to utilize oxygen. Moreover, acetaldehyde promotes GSH depletion, free-radical-mediated toxicity, and lipid peroxidation. In addition, acetaldehyde affects hepatic collagen synthesis; both in vivo (in our baboon model of alcoholic cirrhosis) and in vitro (in cultured myofibroblasts and lipocytes); ethanol and its metabolite acetaldehyde were found to increase collagen accumulation and mRNA levels for collagen. This new understanding may eventually improve therapy with drugs and nutrients. Encouraging results have been obtained with some "super" nutrients. On the one hand, SAMe, the active form of methionine, was found to attenuate the ethanol-induced depletion in SAMe and GSH and associated mitochondrial lesions. On the other hand, phosphatidylcholine, purified from polyunsaturated lecithin, was discovered to oppose the ethanol-induced fibrosis by decreasing the activation of lipocytes to transitional cells, and possibly also by stimulating collagenase activity, an effect for which dilinoleoylphosphatidylcholine, its major phospholipid species, was found to be responsible.
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PMID:Biochemical factors in alcoholic liver disease. 833 2

Some recent proposals in management of alcoholic liver disease are discussed focusing on early diagnosis and treatment of alcohol abuse itself, alcoholic hepatitis early mortality, clinical meaning of nutritional therapy, serological approach and treatment of hepatic fibrosis, and problems in liver transplantation for end stage alcoholic liver cirrhosis. CAGE or similar systematized brief questionnaires, and desialylated transferrin/total transferrin ratio as serological marker, seems to be interesting contributions to "hidden" alcohol abuse diagnosis and abstinence control while psycho-social support and voluntary incorporation to self-aid groups are the best weapons to reach persistent abstinence. Corticosteroids seems to improve survival in a selected group of patients with severe alcoholic hepatitis, specially in those presenting encephalopathy but free of GI bleeding, decompensated diabetes, active infections, pancreatitis, and other contraindications or adverse effects of these drugs. Relationship between direct toxicity and nutritional deficiencies in pathogenesis of alcoholic liver injury are not clear enough, but malnutrition is generally present in patients requiring hospitalization, and related to clinical severity; oral, enteral or parenteral nutritional supplementation in this order of preference according to patients condition, associated or not with steroid anabolics, are useful in cases with moderate to severe alcoholic hepatitis or decompensated cirrhosis to eliminate the catabolic state, reaching a better nitrogen balance and liver function tests, without special adverse effects. A special role on liver regeneration is discussed. Antioxidants and supernutrients are special "modern" aspects of nutritional therapy in alcoholic liver disease generally related to the MEOS activation in chronic alcoholism, the excessive production of free radicals, and the depletion of glutathione, membrane phospholipids (specially phosphatidycholine), and vitamin A, E, and C. Natural supplements as soybean polyunsaturated lecithin, with high concentration of phosphatidycholine, or oral supplementation with natural metabolic products depleted from the liver of chronic heavy drinkers, such SAMe, have an interesting rationale based on experimental and clinical findings besides availability and costs. Carotenoids and tocopherols supplementation seems to be an useful tool, but are limited in the case of vitamin A because its special toxicity in chronic alcoholism. Serological markers of metabolism of liver connective tissue are clearly involved in fibrogenesis process and other inflammatory connected events; standardization of laboratory methods surely will result in new possibilities of non-invasive valuation of liver injury, evolution and therapeutic response; special histological damage such as sinusoidal "cappilarization" (type i.v. collagen and laminin), endothelial sinusoidal cell function (seric hyaluronate), or collagenase activity (TIMP-1 or tissue inhibitor of metalloproteinases-1) seems to be valuable by these new technologies.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:[New suggestions for the management of alcoholic liver diseases]. 852 63

We evaluated the mechanism of increased serum concentrations of the 7S fragment of the N-terminal domain of type IV collagen (7S collagen) in chronic liver disease. We measured the concentrations of hepatic-free and deposited 7S collagens after extraction with Tris-HCl buffer and bacterial collagenase, then compared them with the serum levels in 8 normal controls and 48 patients with chronic liver disease. The hepatic 7S collagen levels extracted with Tris-HCl buffer and collagenase accounted for 7% and 93%, respectively, of the total 7S collagen levels in normal controls. Both hepatic 7S collagen levels as well as serum levels increased in accordance with the progress of liver disease. Serum levels of 7S collagen showed a closer correlation with the hepatic 7S collagen levels extracted with Tris-HCl buffer (r = .822), compared with those extracted with collagenase (r = .382). On the other hand, the histological degrees of liver fibrosis were highly correlated with the hepatic collagenase-extracted 7S collagen levels (r = .822), compared with serum and the hepatic Tris-HCl buffer-extracted levels (r = .478 and r = .537, respectively). Although there was no difference in serum and hepatic 7S collagen levels between B and C viral patients, the serum and hepatic Tris-HCl buffer-extracted 7S collagen levels were higher in patients with alcoholic cirrhosis than patients with viral cirrhosis. However, the hepatic collagenase-extracted levels were similar in both groups. Gel filtration demonstrated that the serum and hepatic Tris-HCl buffer-extracted 7S collagens were mainly eluted in the macromolecular 7S collagen-reactive fraction in cirrhosis, whereas the hepatic collagenase-extracted 7S collagen was eluted in the authentic 7S collagen-reactive fraction. The results suggest that serum 7S collagen levels are not a particularly reliable measure of hepatic fibrosis but reflect the enhanced metabolism, especially synthesis of type IV collagen in the liver.
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PMID:Relationship between serum and hepatic 7S fragments of type IV collagen in chronic liver disease. 862 Nov 48

Alcohol affects the liver through metabolic disturbances associated with its oxidation. Redox changes produced by the hepatic alcohol dehydrogenase pathway affect lipid, carbohydrate and protein metabolism. Ethanol is also oxidized in liver microsomes by the ethanol-inducible cytochrome P4502E1, resulting in ethanol tolerance and selective hepatic perivenular damage. Furthermore, P4502E1 activates various xenobiotics, explaining the increased susceptibility of the heavy drinker to the toxicity of anesthetics, commonly used medications (i.e. isoniazid), analgesics (i.e. acetaminophen), and chemical carcinogens. Induction of microsomal enzymes also contributes to vitamin A depletion, enhances its hepatotoxicity and results in increased acetaldehyde generation from ethanol, with formation of protein adducts, glutathione depletion, free-radical-mediated toxicity, and lipid peroxidation. Chronic ethanol consumption strikingly enhances the number of hepatic collagen-producing activated lipocytes. Both in vivo (in our baboon model of alcoholic cirrhosis) and in vitro (in cultured myofibroblasts and activated lipocytes) ethanol and/or its metabolite acetaldehyde increase collagen accumulation and mRNA for collagen. Gender differences are related, in part, to lower gastric ADH activity (with consequent reduction of first pass ethanol metabolism) in young women, decreased hepatic fatty acid binding protein and increased free-fatty acid levels as well as lesser omega-hydroxylation, all of which result in increased vulnerability to ethanol. Elucidation of the biochemical effects of ethanol are now resulting in improved therapy: in baboons, S-adenosyl-L-methionine attenuates the ethanol-induced glutathione depletion and associated mitochondrial lesions, and polyenylphosphatidylcholine opposes the ethanol-induced hepatic phospholipid depletion, the decrease in phosphatidylethanolamine methyltransferase activity and the activation of hepatic lipocytes, with full prevention of ethanol-induced septal fibrosis and cirrhosis; its dilinoleoyl species also increases collagenase activity in lipocytes. The efficacy of this compound in man is now being studied in randomized multicenter clinical trials.
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PMID:Susceptibility to alcohol-related liver injury. 897 51

Activation of methionine to S-adenosylmethionine is depressed in alcoholics. Its repletion opposes alcoholic liver cirrhosis in baboons, decreases mortality in cirrhotic patients, and opposes oxidative stress resulting from cytochrome P4502E1 (CYP2E1) induction by alcohol, ketones, and fatty acids. Their excess causes alcoholic and nonalcoholic steatohepatitis. CYP2E1 is also induced in Kupffer cells, promoting their activation and release of inflammatory cytokines, including tumor necrosis factor (TNF)-alpha. The TNF-alpha inhibitor pentoxifylline decreased mortality from alcoholic hepatitis. Polyenylphosphatidylcholine (PPC), an antioxidant phosphatidylcholine mixture extracted from soybeans, 50% of which consists of the highly bioavailable dilinoleoylphosphatidylcholine, restores phospholipids of the damaged membranes and reactivates their enzymes, including phosphatidylethanolamine methyltransferase, needed for phospholipid regeneration. In baboons, PPC prevented cirrhosis by stimulating collagenase and by opposing lipid peroxidation, which produces the fibrogenic hydroxynonenal. PPC was beneficial in patients with alcoholic hepatitis, and it opposed fibrosis in heavy drinkers and decreased aminotransferases in patients with hepatitis C. The antioxidant silymarin also successfully opposed alcoholic cirrhosis in baboons and in some but not all clinical trials; this effect also pertains to a-tocopherol. The anti-inflammatory corticosteroids and colchicine yielded mixed results. Finally, replacing long-chain with medium-chain triglycerides opposed the fatty liver experimentally and clinically.
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PMID:New concepts of the pathogenesis of alcoholic liver disease lead to novel treatments. 1472 Apr 55

In alcoholic liver cirrhosis, normal liver cells are replaced by scar tissue (fibrosis). Liver fibrosis is a dynamic process in which activated hepatic stellate cells are involved in the synthesis of matrix proteins and the regulation of matrix degeneration. The aim of the presented study was to assess the usefulness of MMP-2, MMP-8 and MMP-9 as diagnostic markers of alcoholic liver disease. Sixty patients with alcoholic liver cirrhosis were randomly enrolled during hospitalization in departments of hospitals from the Lublin Region in eastern Poland. The stage of cirrhosis was estimated according to Child-Turcotte-Pugh criteria (Child-Pugh score) as P- Ch A, P-Ch B, P-Ch C. The control group consisted of 10 healthy persons without liver disease, who did not drink alcohol. Additionally, a group of alcoholics without liver cirrhosis was included in the study. Blood sample were obtained, and after centrifuge, serum was collected for further analysis. The activity of MMP-2, MMP-8 and MMP-9 in the blood plasma of the patients and the control group were measured by using the sandwich enzyme immunoassay technique with commercially available quantitative ELISA test kits. Activity of MMP-2, MMP-8 and MMP-9 in patients with liver cirrhosis were increased gradually according to Child-Pugh stages. The activity of MMP-2, MMP-8, MMP-9 were the highest in patients with liver cirrhosis stage C. MMP-2, MMP-8, MMP-9 concentrations in the people with liver cirrhosis (stage C) were significantly increased compared to controls. A significant difference were observed between activity MMP-2 in control group, alcoholics without liver cirrhosis, and those with liver cirrhosis (stages A, B, C according Child-Pugh score). MMP-2, MMP-8 and MMP-9 may be markers of alcoholic liver cirrhosis in the alcoholics. Elevated levels of MMP-2, MMP-8 and MMP-9 in the alcoholic patients indicated that cirrhosis has developed. The most sensitive is MMP-2, because the activity of this parameter is increased in all liver cirrhosis stages. MMP-8 and MMP-9 activity were significantly elevated only in serum patients with advanced liver cirrhosis, compared to controls.
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PMID:Activity of MMP-2, MMP-8 and MMP-9 in serum as a marker of progression of alcoholic liver disease in people from Lublin Region, eastern Poland. 2609 32