cyanoginosin-lr and Disease-Models--Animal

Inflammatory bowel disease (IBD) is a chronic, lifelong gastrointestinal disease, characterized by periods of activity and remission. The etiology of IBD is closely related to environmental factors. Previous studies have shown that the cyanotoxin microcystin-LR (MC-LR) causes intestinal damage, even IBD. To explore MC-LR's effects and potential mechanisms on IBD occurrence and development, we used dextran-sulfate sodium gavage (DSS) and MC-LR together for the first time in mice. There were four groups of mice: (A) mice given PBS gavage (control, CT); (B) mice given 3% DSS gavage (DSS); (C) mice given 200 µg/kg MC-LR gavage (MC-LR); and (D) mice given 3% DSS + 200 µg/kg MC-LR gavage (DSS + MC-LR). Compared with the CT group, the MC-LR group and the DSS group demonstrated more severe colitis results, which presented as higher weight loss, an increased Disease Activity Index (DAI) score, shorter colon length, a higher degree of tissue structural damage, more apoptotic cells, and greater pro-inflammatory cytokines. Similarly, the DSS + MC-LR group showed more severe colitis compared with the DSS group. Subsequent experiments confirmed that MC-LR or DSS increased the expression of pyroptosis-related proteins mediated by the nucleotide-binding domain-like receptor protein 3 (NLRP3). Likewise, compared with the DSS group, the DSS + MC-LR group expressed these proteins at a higher level. In conclusion, our research is the first to show that MC-LR may induce colitis, and even IBD, through NLRP3 inflammasome-mediated pyroptosis, and it could aggravate DSS-induced colitis in the same way.

Topics: Animals; Colitis; Disease Models, Animal; Inflammasomes; Inflammatory Bowel Diseases; Mice; Mice, Inbred C57BL; NLR Family, Pyrin Domain-Containing 3 Protein; Pyroptosis

We were the first to previously report that microcystin-LR (MC-LR) has limited effects within the colons of healthy mice but has toxic effects within colons of mice with pre-existing inflammatory bowel disease. In the current investigation, we aimed to elucidate the mechanism by which MC-LR exacerbates colitis and to identify effective therapeutic targets. Through our current investigation, we report that there is a significantly greater recruitment of macrophages into colonic tissue with pre-existing colitis in the presence of MC-LR than in the absence of MC-LR. This is seen quantitatively through IHC staining and the enumeration of F4/80-positive macrophages and through gene expression analysis for

Topics: Animals; Biomarkers; Colitis; Colon; Dextran Sulfate; Disease Models, Animal; Gene Expression Regulation; Inflammation; Macrophages; Male; Marine Toxins; Mice, Inbred C57BL; Mice, Knockout; Microcystins; Naphthalenes; Protein Kinases; Proteome; Pyrazoles; Rats

Nonalcoholic steatohepatitis (NASH) causes liver extracellular matrix (ECM) remodeling and is a risk factor for fibrosis and hepatocellular carcinoma (HCC). Microcystin-LR (MCLR) is a hepatotoxin produced by fresh-water cyanobacteria that causes a NASH-like phenotype, liver fibrosis, and is also a risk factor for HCC. The focus of the current study was to investigate and compare hepatic recovery after cessation of MCLR exposure in healthy versus NASH animals. Male Sprague-Dawley rats were fed either a control or a high fat/high cholesterol (HFHC) diet for eight weeks. Animals received either vehicle or 30 μg/kg MCLR (i.p: 2 weeks, alternate days). Animals were euthanized at one of three time points: at the completion of the MCLR exposure period and after 2 and 4 weeks of recovery. Histological staining suggested that after four weeks of recovery the MCLR-exposed HFHC group had less steatosis and more fibrosis compared to the vehicle-exposed HFHC group and MCLR-exposed control group. RNA-Seq analysis revealed dysregulation of ECM genes after MCLR exposure in both control and HFHC groups that persisted only in the HFHC groups during recovery. After 4 weeks of recovery, MCLR hepatotoxicity in pre-existing NASH persistently dysregulated genes related to cellular differentiation and HCC. These data demonstrate impaired hepatic recovery and persistent carcinogenic changes after MCLR toxicity in pre-existing NASH.

Topics: Animals; Carcinoma, Hepatocellular; Cell Differentiation; Diet, High-Fat; Disease Models, Animal; Extracellular Matrix; Liver Cirrhosis; Liver Neoplasms; Male; Marine Toxins; Microcystins; Non-alcoholic Fatty Liver Disease; Rats; Rats, Sprague-Dawley; Time Factors

Nonalcoholic fatty liver disease (NAFLD) has been shown to be associated with extrahepatic comorbidities including neuronal inflammation and Alzheimer's-like pathology. Environmental and genetic factors also act as a second hit to modulate severity and are expected to enhance the NAFLD-linked neuropathology. We hypothezied that environmental microcystin-LR (MC-LR), a toxin produced by harmful algal blooms of cyanobacteria, exacerbates the neuroinflammation and degeneration of neurons associated with NAFLD. Using a mouse model of NAFLD, exposed to MC-LR subsequent to the onset of fatty liver, we show that the cyanotoxin could significantly increase proinflammatory cytokine expression in the frontal cortex and cause increased expression of Lcn2 and HMGB1. The above effects were NLRP3 inflammasome activation-dependent since the use of NLRP3 knockout mice abrogated the increase in inflammation. NLRP3 was also responsible for decreased expression of the blood-brain barrier (BBB) tight junction proteins Occludin and Claudin 5 suggesting BBB dysfunction was parallel to neuroinflammation following microcystin exposure. An increased circulatory S100B release, a hallmark of astrocyte activation in MC-LR exposed NAFLD mice also confirmed BBB integrity loss, but the astrocyte activation observed in vivo was NLRP3 independent suggesting an important role of a secondary S100B mediated crosstalk. Mechanistically, conditioned medium from reactive astrocytes and parallel S100B incubation in neuronal cells caused increased inducible NOS, COX-2, and higher BAX/ Bcl2 protein expression suggesting oxidative stress-mediated neuronal cell apoptosis crucial for neurodegeneration. Taken together, MC-LR exacerbated neuronal NAFLD-linked comorbidities leading to cortical inflammation, BBB dysfunction, and neuronal apoptosis.

Topics: Animals; Apoptosis; Blood-Brain Barrier; Disease Models, Animal; Environmental Exposure; Inflammasomes; Inflammation; Male; Marine Toxins; Mice; Mice, Inbred C57BL; Mice, Knockout; Microcystins; Neuroinflammatory Diseases; NLR Family, Pyrin Domain-Containing 3 Protein; Non-alcoholic Fatty Liver Disease; Oxidative Stress; S100 Calcium Binding Protein beta Subunit

Idiopathic pulmonary fibrosis (IPF) is a group of chronic interstitial pulmonary diseases characterized by myofibroblast proliferation and extracellular matrix deposition with limited treatment options. Based on our previous observation, we hypothesized microcystin-leucine arginine (LR), an environmental cyanobacterial toxin, could potentially suppress pulmonary fibrosis. In this study, we first demonstrated that chronic exposure of microcystin-LR by oral for weeks indeed attenuated the pulmonary fibrosis both on bleomycin-induced rat and fluorescein isothiocyanate-induced mouse models. Our data further indicated that treatment with microcystin-LR substantially reduced TGF-β1/Smad signaling in rat pulmonary tissues. The experiments in vitro found that microcystin-LR was capable of blocking epithelial-mesenchymal transition (EMT) and fibroblast-myofibroblast transition (FMT) through suppressing the differentiation of CD206

Topics: A549 Cells; Animals; Disease Models, Animal; Endoplasmic Reticulum Chaperone BiP; Fibroblasts; Heat-Shock Proteins; Humans; Idiopathic Pulmonary Fibrosis; Lectins, C-Type; Lung; Macrophages; Male; Mannose Receptor; Mannose-Binding Lectins; Marine Toxins; Mice; Mice, Inbred C57BL; Microcystins; NIH 3T3 Cells; Phenotype; Protein Phosphatase 2; Rats, Sprague-Dawley; RAW 264.7 Cells; Receptors, Cell Surface; Signal Transduction; Smad Proteins; Transforming Growth Factor beta1

Microcystin-LR has a toxic effect on several organs causing the destruction and fibrosis of these organs. This study was done to evaluate the antioxidant activity of silymarin on some oxidative stress parameters on heart and lung injuries induced by microcystin-LR in mice.. Total 72 Balb/c male mice aged between five to seven weeks were grouped into 6; Group 1 contained twelve mice which were assigned as the healthy control group (C). Two microcystin-LR control groups assigned M6 and M12 contain 12 mice each. A fourth group contains twelve mice called the silymarin control group(S). The fifth and sixth groups contain twenty-four mice assigned as microcystin-LR silymarin groups SM6 and SM12. A blood sample was collected for estimation of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST). The homogenates of heart and lungs were extracted for estimation of protein carbonyl content (CC), lipid peroxidation products (LPO), reduced glutathione (GSH), methylglyoxal (MG) and activity of protein phosphatase I (PPI).. Significant statistical differences in both ALT and AST were observed between all groups (P>0.01). In cardiac homogenate, a significant statistical difference was observed in PPI, LPO and CC between all groups (P<0.05). Furthermore, methylglyoxal showed a significant statistical difference between all groups (p<0.01).. The findings suggested a potential therapeutic role of using silymarin as an antioxidant agent against cardiac and pulmonary injuries induced by MC-LR.

Topics: Animals; Antioxidants; Biomarkers; Cardiotoxicity; Disease Models, Animal; Glutathione; Heart Diseases; Lipid Peroxidation; Lung; Male; Marine Toxins; Mice, Inbred BALB C; Microcystins; Myocytes, Cardiac; Oxidative Stress; Protein Carbonylation; Protein Phosphatase 1; Pulmonary Fibrosis; Pyruvaldehyde; Silymarin

Microcystin-LR (MC-LR) is a potent hepatotoxin that has also been pointed out of causing neurotoxicity, but the exact mechanisms of action still remain ambiguous and need to be elucidated. Data from studies on mammals show that pathology of astrocyte cells points to perturbations of microRNA signaling. Glial fibrillary acidic protein (GFAP), a neuronal cell/astrocyte-specific protein, and a microRNA-124-3p (MiR124-3p) are among putative triggers and regulators of neuronal cell/astrocyte reactivity. In the present study on whitefish (Coregonus lavaretus), we found that gfap mRNA contains a putative target site for MIR124-3p, to potentially affect its expression changes. qPCR expression study of gfap:MiR124-3p pair in the midbrain of juvenile whitefish, during 28 days of exposure to a repeated subacute dose of MC-LR (100 μg kg

Topics: Animals; Animals, Genetically Modified; Brain; Disease Models, Animal; Enzyme Inhibitors; Glial Fibrillary Acidic Protein; HEK293 Cells; Humans; Marine Toxins; Microcystins; MicroRNAs; Neurotoxicity Syndromes; Phylogeny; Salmonidae; Transfection; Up-Regulation

Recent studies showed that cyanobacteria-derived microcystin-leucine-arginine (MCLR) can cause hippocampal pathological damage and trigger cognitive impairment; but the underlying mechanisms have not been well understood. The objective of the present study was to investigate the mechanism of MCLR-induced cognitive deficit; with a focus on endoplasmic reticulum (ER) stress. The Morris water maze test and electrophysiological study demonstrated that MCLR caused spatial memory injury in male Wistar rats; which could be inhibited by ER stress blocker; tauroursodeoxycholic acid (TUDCA). Meanwhile; real-time polymerase chain reaction (real-time PCR) and immunohistochemistry demonstrated that the expression level of the 78-kDa glucose-regulated protein (GRP78); C/EBP homologous protein (CHOP) and caspase 12 were significantly up-regulated. These effects were rescued by co-administration of TUDCA. In agreement with this; we also observed that treatment of rats with TUDCA blocked the alterations in ER ultrastructure and apoptotic cell death in CA1 neurons from rats exposed to MCLR. Taken together; the present results suggested that ER stress plays an important role in potential memory impairments in rats treated with MCLR; and amelioration of ER stress may serve as a novel strategy to alleviate damaged cognitive function triggered by MCLR.

Topics: Animals; Apoptosis; Cognition Disorders; Disease Models, Animal; Endoplasmic Reticulum Stress; Hippocampus; Male; Marine Toxins; Maze Learning; Memory; Microcystins; Neuronal Plasticity; Rats

Black band disease (BBD) of corals is a complex pathogenic polymicrobial mat community that lyses coral tissue as it migrates over an infected colony. Two known toxins are produced by BBD microorganisms - sulfide, produced by sulfate-reducing bacteria, and microcystin, produced by cyanobacteria. Experiments were carried out to determine the effects of exposing healthy coral fragments to variable concentrations of purified microcystin, sulfide at a concentration known to exist in BBD, and a combination of the two. Healthy fragments of the coral Montastraea annularis were placed into experimental chambers with known toxin/s for 18-22.5 h. Fine structural analysis using scanning electron microscopy (SEM) showed that toxin exposure resulted in thinning or removal of the coral epidermal layer coupled with degradation of the gastrodermis. These effects were exacerbated when both toxins were used in combination. Exposure to sulfide and the highest concentration of microcystin caused zooxanthellae to dissociate from the coral tissue and to form clusters on the coral surface. Examination of coral fragments infected with BBD was carried out for comparison. It was determined that the effects of exposure to sulfide and microcystin on coral fine structure were consistent, both quantitatively and qualitatively, with the effects of artificially induced and naturally occurring BBD on M. annularis.

Topics: Animal Diseases; Animals; Anthozoa; Bacterial Infections; Bacterial Toxins; Disease Models, Animal; Epidermis; Marine Toxins; Microcystins; Sulfides

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

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