cyanoginosin-lr and Liver-Diseases

Microcystin-LR (MC-LR) is a potent hepatotoxin that can cause liver inflammation and injury. However, the mode of action of related inflammatory factors is not fully understood. PfHMGB1 is an inflammatory factor induced at the mRNA level in the liver of juvenile yellow catfish (Pelteobagrus fulvidraco) that were intraperitoneally injected with 50 μg/kg MC-LR. The PfHMGB1 mRNA level was highest in the liver and muscle among 11 tissues examined. The full-length cDNA sequence of PfHMGB1 was cloned and overexpressed in E. coli, and the purified protein rPfHMGB1 demonstrated DNA binding affinity. Endotoxin-free rPfHMGB1 (6-150 μg/mL) also showed dose-dependent hepatotoxicity and induced inflammatory gene expression of primary hepatocytes. PfHMGB1 antibody (anti-PfHMGB1) in vitro reduced MC-LR (30 and 50 μmol/L)-induced hepatotoxicity, suggesting PfHMGB1 is important in the toxic effects of MC-LR. In vivo study showed that MC-LR upregulated PfHMGB1 protein in the liver. The anti-PfHMGB1 blocked its counterpart and reduced ALT/AST activities after MC-LR exposure. Anti-PfHMGB1 partly neutralized MC-LR-induced hepatocyte disorganization, nucleus shrinkage, mitochondria, and rough endoplasmic reticula destruction. These findings suggest that PfHMGB1 promotes MC-LR-induced liver damage in the yellow catfish. HMGB1 may help protect catfish against widespread microcystin pollution.

Topics: Animals; Catfishes; Chemical and Drug Induced Liver Injury, Chronic; DNA, Complementary; Escherichia coli; Gene Expression; Hepatocytes; Liver; Liver Diseases; Marine Toxins; Microcystins; Proteins; RNA, Messenger

Microcystin poisoning was diagnosed in a dog exposed to a Microcystis aeruginosa-dominated, freshwater, harmful algal bloom at Milford Lake, Kansas, which occurred during the summer of 2011. Lake water microcystin concentrations were determined at intervals during the summer, using competitive enzyme-linked immunosorbent assays, and indicated extremely high, localized microcystin concentrations of up to 126,000 ng/ml. Multiple extraction and analysis techniques were used in the determination of free and total microcystins in vomitus and liver samples from the poisoned dog. Vomitus and liver contained microcystins, as determined by enzyme-linked immunosorbent assays, and the presence of microcystin-LR was confirmed in vomitus and liver samples using liquid chromatography coupled with tandem mass spectrometry. Major toxic effects in a dog presented for treatment on the day following exposure included fulminant liver failure and coagulopathy. The patient deteriorated rapidly despite aggressive treatment and was euthanized. Postmortem lesions included diffuse, acute, massive hepatic necrosis and hemorrhage, as well as acute necrosis of the renal tubular epithelium. A diagnosis of microcystin poisoning was based on the demonstration of M. aeruginosa and microcystin-LR in the lake water, as well as in vomitus produced early in the course of the poisoning; the presence of microcystin-LR in liver tissue; and a typical clinical course including gastroenteritis and fulminant liver failure.

Topics: Animals; Dog Diseases; Dogs; Fatal Outcome; Harmful Algal Bloom; Kansas; Lakes; Liver Diseases; Marine Toxins; Microcystins; Microcystis; Water Microbiology

Cyanobacterial blooms and hepatotoxic microcystins (MCs) usually occur in summer, constituting a sanitary and environmental problem in Salto Grande Dam, Argentina. Water sports and recreational activities take place in summer in this lake. We reported an acute case of cyanobacterial poisoning in Salto Grande dam, Argentina, which occurred in January 2007. Accidentally, a young man was immersed in an intense bloom of Microcystis spp. A level of 48.6 μg·L(-1) of microcystin-LR was detected in water samples. Four hours after exposure, the patient showed nausea, abdominal pain and fever. Three days later, dyspnea and respiratory distress were reported. The patient was hospitalized in intensive care and diagnosed with an atypical pneumonia. Finally, a week after the exposure, the patient developed a hepatotoxicosis with a significant increase of hepatic damage biomarkers (ALT, AST and γGT). Complete recovery took place within 20 days. This is the first study to show an acute intoxication with microcystin-producing cyanobacteria blooms in recreational water.

Topics: Argentina; Bacterial Toxins; Biomarkers; Harmful Algal Bloom; Humans; Liver Diseases; Liver Function Tests; Male; Marine Toxins; Microcystins; Microcystis; Pneumonia; Recreation; Water Microbiology; Young Adult

Microcystin-LR (MC-LR) produced by cyanobacteria in diverse water systems is a potent specific hepatotoxin and has been documented to induce various liver diseases via oxidative stress. However, the underlying mechanisms are largely unknown. In the current study, we investigated the molecular events involved in the oxidative liver injury by MC-LR. Our results demonstrated that MC-LR induced liver injury in mice through a series of steps that began with the production of reactive oxygen species (ROS), which stimulated the sustained activation of JNK and its downstream targets, AP-1 and Bid. Furthermore, the mitochondrial proteomic analysis indicated that JNK activation affected some crucial enzymes of energy metabolism, led to mitochondria dysfunction, which contributed to hepatocyte apoptosis and oxidative liver injury by MC-LR. Our results reveal significant insights into the mechanisms of liver injury induced by microcystins, and serve as a framework for deciphering the role of JNK in oxidative stress-associated liver diseases.

Topics: Animals; BH3 Interacting Domain Death Agonist Protein; Chemical and Drug Induced Liver Injury; Disease Models, Animal; Enzyme Inhibitors; Hepatocytes; JNK Mitogen-Activated Protein Kinases; Liver Diseases; Marine Toxins; Mice; Microcystins; Oxidative Stress; Reactive Oxygen Species; Signal Transduction; Transcription Factor AP-1

The effect of sub-chronic exposure of intraperitoneal (i.p.) injections of microcystin-LR (MC-LR) on microscopic tissue architecture, hepatic function and lipid peroxidation has been studied in liver and kidney of mice. Mice were treated i.p. with 25 microg of pure MC-LR/kg body weight or saline solution for 1 month (every 2 days) with the aim of producing an inflictive stage with evident damage. Histopathological analysis of dissected livers of mice showed a disrupted lobar architecture and the development of cytoplasmatic vacuoles. According to this, a significant increase in hepatic lipid content and in lipid peroxidation levels in liver and kidney was found in MC-LR-treated animals when compared with controls. Moreover, serum alkaline phosphatase and aspartate aminotransferase activities showed a significant alteration in MC-LR-treated animals. After damage, progression or recovery was studied for 1 and 2 months of wash-out. The recovery from liver damage was evident at the cytological and physiological level, only the recovery of lobar architecture was incomplete along the period investigated. In conclusion, the present study demonstrates the ability of hepatic tissue to recover from damage produced by sub-chronic MC-LR administration. The dynamic interplay between damage and tissue-repairing response in determining the ultimate outcome of toxicity should be considered in risk-assessment studies.

Topics: Animals; Chemical and Drug Induced Liver Injury; Creatinine; Drug Administration Schedule; Lipid Peroxidation; Lipids; Liver Diseases; Male; Marine Toxins; Mice; Microcystins; Urea; Weight Gain

Microcystin-LR (MC-LR) produced by cyanobacteria in diverse water systems is a potent specific hepatotoxin and has been documented to induce hepatocyte apoptosis and liver injury; however, the mechanisms have not been fully elucidated. In the present study, we investigated whether MC-LR stimulated ROS generation in the liver of mice and the role of ROS in the pathogenesis of MC-LR-induced liver injury in vivo. MC-LR treatment (60 microg/kg of body weight) for 12h prompted large amount of ROS generation in mice liver, upregulated the expression of Bax and Bid, caused the mitochondrial membrane potential (MMP) loss and hepatocyte apoptosis as well as liver injury. While pretreatment with antioxidants, oral administration of vitamin C (250mg/kg of body weight, dissolved in double distill water) and vitamin E (200mg/kg of body weight, dissolved in corn oil) per day for 3 days continually, significantly reduced the generation of ROS and effectively inhibited the MC-LR-induced hepatocyte apoptosis and liver injury, suggesting that ROS played a critical role in MC-LR-induced hepatocyte apoptosis and liver injury. The protective effect of vitamin C and E also suggested the potential interest in the clinical treatment of MC-LR-induced liver injury and hepatotoxicity.

Topics: Alanine Transaminase; Animals; Antioxidants; Apoptosis; Ascorbic Acid; Aspartate Aminotransferases; bcl-2-Associated X Protein; BH3 Interacting Domain Death Agonist Protein; Chemical and Drug Induced Liver Injury; Hepatocytes; Histocytochemistry; Liver Diseases; Male; Malondialdehyde; Marine Toxins; Membrane Potential, Mitochondrial; Mice; Mice, Inbred ICR; Microcystins; Random Allocation; Reactive Oxygen Species; Rhodamines; Vitamin E

Keratin 8 (K8) variants predispose to human liver injury via poorly understood mechanisms. We generated transgenic mice that overexpress the human disease-associated K8 Gly61-to-Cys (G61C) variant and showed that G61C predisposes to liver injury and apoptosis and dramatically inhibits K8 phosphorylation at serine 73 (S73) via stress-activated kinases. This led us to generate mice that overexpress K8 S73-to-Ala (S73A), which mimicked the susceptibility of K8 G61C mice to injury, thereby providing a molecular link between K8 phosphorylation and disease-associated mutation. Upon apoptotic stimulation, G61C and S73A hepatocytes have persistent and increased nonkeratin proapoptotic substrate phosphorylation by stress-activated kinases, compared with wild-type hepatocytes, in association with an inability to phosphorylate K8 S73. Our findings provide the first direct link between patient-related human keratin variants and liver disease predisposition. The highly abundant cytoskeletal protein K8, and possibly other keratins with the conserved S73-containing phosphoepitope, can protect tissue from injury by serving as a phosphate "sponge" for stress-activated kinases and thereby provide a novel nonmechanical function for intermediate filament proteins.

Topics: Animals; Apoptosis; Chemical and Drug Induced Liver Injury; Disease Models, Animal; Fas Ligand Protein; Genetic Predisposition to Disease; Genetic Variation; Hepatocytes; Humans; Intermediate Filament Proteins; Keratin-8; Keratins; Liver Diseases; Liver Function Tests; Marine Toxins; Membrane Glycoproteins; Mice; Mice, Knockout; Mice, Transgenic; Microcystins; Mitogen-Activated Protein Kinases; Mutation; Peptides, Cyclic; Phosphorylation; Tumor Necrosis Factors

Toxin-producing cyanobacteria pose a worldwide health threat to humans and animals due to their increasing presence in both drinking and recreational waters. Little work has, however, been done on a preventative therapy for anyone at risk of exposure to cyanobacterial toxins. The potential benefits of dietary supplementation of selenium, an antioxidant, to protect against the mouse liver injury induced by the toxin, microcystin-LR, has been investigated. BALB/c mice were pretreated for two weeks with sodium selenite (1.5 microg/mouse/day) before an intraperitoneal injection of microcystin-LR. Selenium-supplementation was found to provide some protection to the action of the toxin. In addition selenium pretreatment reduced the liver damage caused by lethal and sub-lethal toxin doses as reflected in liver pathology, decreased serum ALT and lipid peroxidation levels as well as prevention of glycogen loss compared to non-selenium supplemented toxin treated mice. The increased level of liver glutathione peroxidase activity following selenium-supplementation may indicate the possible route of selenium protection in the mice.

Topics: Alanine Transaminase; Animals; Bacterial Toxins; Chemical and Drug Induced Liver Injury; Cyanobacteria; Dietary Supplements; Dose-Response Relationship, Drug; Lethal Dose 50; Liver; Liver Diseases; Marine Toxins; Mice; Mice, Inbred BALB C; Microcystins; Peptides, Cyclic; Sodium Selenite

The objective of this study was to elucidate whether microcystin-LR (MC-LR), a hepatotoxic blue-green algal toxin in drinking water, is carcinogenic or possesses the ability to modulate aflatoxin B1 (AFB1)-induced hepatocarcinogenicity. In a medium-term liver bioassay, male Fischer 344 rats were given a single i.p. injection of diethylnitrosamine (DEN, 200 mg/kg) followed by an i.p. injection of MC-LR for 6 weeks after 2 weeks of DEN treatment. To study the synergism between AFB1 and MC-LR, DEN-treated rats were given an i.p. injection of AFB1 (0.5 mg/kg) dissolved in dimethyl sulfoxide (DMSO) followed by MC-LR at 2 weeks after the treatment. In a separate experiment, the rats were first given AFB1 (0.5 mg/kg) and 2 weeks later an i.p. injection of 1 or 10 microg/kg of MC-LR twice a week for 6 weeks. Most rats were subjected to a two-thirds partial hepatectomy (PH) at week 3 and were killed under anesthesia at week 8. Liver sections were analyzed for glutathione S-transferase placental form (GST-P) expression, and subjected to histopathological examination for phenotypic alteration of hepatocellular foci. In rats that did not receive DEN, MC-LR did not cause a significant increase in the numbers of GST-P-positive foci, whereas AFB1 induced a slight increase in GST-P-positive foci development. In rats given DEN, MC-LR enhanced the expression of GST-P-positive foci, as did AFB1 but no synergism was observed. Histopathological analysis revealed that the area of eosinophilic foci, a biomarker for preneoplastic liver lesion, markedly increased because of MC-LR. In rats given AFB1 as an initiator, treatment with MC-LR resulted in a synergistic increase in the development of GST-P-positive foci. These results suggest that the hepatocarcinogenicities of MC-LR and AFB1 can be predicted in experimental animals with a medium-term bioassay. Furthermore, tumor promoting activity of MC-LR was demonstrated in rats treated with AFB1.

Topics: Aflatoxin B1; Animals; Bacterial Toxins; Biomarkers; Chemical and Drug Induced Liver Injury; Diethylnitrosamine; Drug Synergism; Glutathione Transferase; Hepatectomy; Isoenzymes; Liver; Liver Diseases; Male; Marine Toxins; Microcystins; Organ Specificity; Peptides, Cyclic; Placenta; Precancerous Conditions; Rats; Rats, Inbred F344

Evidence is presented that links microcystins to a severe liver disease that occurs in Atlantic salmon that are netpen-reared in coastal British Columbia. Liquid chromatography-linked protein phosphatase bioassay analysis of extracts of liver tissue taken from Atlantic salmon afflicted with netpen liver disease showed the presence of an inhibitor of protein phosphatase that was chromatographically indistinguishable from microcystin-LR. Analysis of liver tissue from healthy control fish showed a complete absence of microcystin-LR. Intraperitoneal injection of microcystin-LR into healthy Atlantic salmon re-created the pathologic changes of netpen liver disease, including diffuse necrosis and hepatic megalocytosis.

Topics: Animals; Aquaculture; Chromatography, Liquid; Fish Diseases; Liver Diseases; Marine Toxins; Microcystins; Peptides, Cyclic; Phosphoprotein Phosphatases; Salmon

Sprague-Dawley rats were used to evaluate a model system for studying the hepatotoxicity caused by microcystin-LR (MCYST-LR), a toxin produced by the cyanobacterium (blue-green alga) Microcystis aeruginosa, and for evaluating the in vivo therapeutic potential of cholestyramine resin (CTR) which was found to bind the toxin in vitro. Female rats were treated with either toxin or an equivalent volume of the saline vehicle by direct administration into the lumen of an in situ isolated ileal loop. Male rats were dosed with toxin as described above, and then animals were dosed in the ileal loop with either cholestyramine resin (CTR, 50 mg/rat) or an equivalent vehicle. The survivors in both studies were killed six hours after dosing and hepatotoxicity was assessed by change in relative liver weights. In all groups given toxin alone, there was a significant increase in liver weight and males and females were equally susceptible. Liver weights of the toxin plus CTR treated rats were similar to those in vehicle-treated rats. When the toxin was administered into a similarly isolated jejunal loop, liver weight was significantly less than that found when an equivalent dose was administered into the ileal loop suggesting an intestinal site specificity for toxin absorption.

Topics: Animals; Biological Availability; Chemical and Drug Induced Liver Injury; Cholestyramine Resin; Female; Ileum; Intestinal Absorption; Jejunum; Ligation; Liver Diseases; Male; Marine Toxins; Microcystins; Microcystis; Models, Biological; Peptides, Cyclic; Rats; Rats, Inbred Strains; Toxins, Biological