cyanoginosin-lr and Kidney-Diseases

Previous studies have reported that microcystin-LR (MC-LR) levels are highly correlated with abnormal renal function indicators, suggesting that MC-LR is an independent risk factor for kidney damage. However, the evidence for the exact regulation mechanism of MC-LR on kidney damage is still limited, and further in-depth exploration is needed. In addition, the mitochondria-related mechanism of MC-LR leading to kidney damage has not been elucidated. To this end, the present study aimed to further explore the mechanism of mitophagy related to kidney damage induced by MC-LR through in vitro and in vivo experiments. Male C57BL/6 mice were fed with a standard rodent pellet and exposed daily to MC-LR (20 μg/kg·bw) via intraperitoneal injections for 7 days. Moreover, HEK 293 cells were treated with MC-LR (20 μM) for 24 h. The histopathological results exhibited kidney damage after MC-LR exposure, characterized by structurally damaged nephrotomies, with inflammatory cell infiltration. Similarly, a significant increase in renal interstitial fibrosis was observed in the kidneys of MC-LR-treated mice compared with those of the control group (CT) mice. MC-LR exposure caused impaired kidney function, with markedly increased blood urea nitrogen (BUN), creatinine (Cr), and uric acid (UA) levels in mice. Ultrastructural analysis exhibited obviously swollen, broken, and disappearing mitochondrial crests, and partial mitochondrial vacuoles in the MC-LR-treated HEK 293 cells. The Western blotting results demonstrated that exposure to MC-LR significantly increased the protein expressions of MKK6, p-p38, and p62, while the expression of mitophagy-related proteins was significantly inhibited in the kidneys of mice and HEK293 cells, including parkin, TOM20, and LC3-II, indicating the inhibition of mitophagy. Therefore, our data suggest that the inhibition of MKK6-mediated mitophagy might be the toxicological mechanism of kidney toxicity in mice with acute exposure to MC-LR.

Topics: Animals; HEK293 Cells; Humans; Kidney; Kidney Diseases; Male; Mice; Mice, Inbred C57BL; Microcystins; Mitophagy

Recently, several studies showed that microcystin-LR (MCLR) can accumulate and induce toxicity in kidney. However, the exact mechanism is unknown. The aim of this study was to explore the mechanism of MCLR-induced nephrotoxicity. To this end, adult zebrafish were exposed to MCLR (0, 1, 5 and 25 μg/L) for 60 days. Exposure to MCLR caused histopathological lesions, which were characterized by renal tubules filled with eosinophilic casts, abnormal renal tubules, intertubular space decrease, and blood infiltration in renal cells. RNA-Seq analysis indicated that exposure to MCLR significantly interfered with renal gene expressions, and these genes were enriched in various pathways, such as oxidative phosphorylation, cell cycle, and protein processing in endoplasmic reticulum, which were related to apoptosis. Furthermore, terminal deoxynucleotide transferase-mediated deoxy-UTP nick end labelling (TUNEL) assay showed that MCLR exposure induced renal cell apoptosis. In addition, negative changes of the reactive oxygen species (ROS) level as well as apoptotic-related gene, protein expressions and enzyme activities suggested that MCLR could induce production of ROS, subsequently triggering apoptosis via p53-bcl-2 and caspase-dependent pathway in the kidney of zebrafish. Therefore, it can be concluded that apoptosis is a primary case of MCLR-induced nephrotoxicity.

Topics: Animals; Apoptosis; Enzyme Inhibitors; Female; Gene Expression Profiling; Gene Expression Regulation; Kidney Diseases; Marine Toxins; Microcystins; Zebrafish

In vivo visualization of kidney and liver damage by Magnetic Resonance Imaging (MRI) may offer an advantage when there is a need for a simple, non-invasive and rapid method for screening of the effects of potential nephrotoxic and hepatotoxic substances in chronic experiments. Here, we used MRI for monitoring chronic intoxication with microcystins (MCs) in rat. Male adult Wistar rats were treated every other day for eight months, either with MC-LR (10 μg/kg i.p.) or MC-YR (10 μg/kg i.p.). Control groups were treated with vehicle solutions. T1-weighted MR-images were acquired before and at the end of the eight months experimental period. Kidney injury induced by the MCs presented with the increased intensity of T1-weighted MR-signal of the kidneys and liver as compared to these organs from the control animals treated for eight months, either with the vehicle solution or with saline. The intensification of the T1-weighted MR-signal correlated with the increased volume density of heavily injured tubuli (R2 = 0.77), with heavily damaged glomeruli (R2 = 0.84) and with volume density of connective tissue (R2 = 0.72). The changes in the MR signal intensity probably reflect the presence of an abundant proteinaceous material within the dilated nephrons and proliferation of the connective tissue. T1-weighted MRI-is a valuable method for the in vivo screening of kidney and liver damage in rat models of intoxication with hepatotoxic and nephrotoxic agents, such as microcystins.

Topics: Animals; Chemical and Drug Induced Liver Injury; Kidney Diseases; Magnetic Resonance Imaging; Male; Marine Toxins; Microcystins; Rats; Rats, Wistar

Microcystins (MCs) are a group of closely related cyclic heptapeptides produced by a variety of common cyanobacteria. These toxins have been implicated in both human and livestock mortality. Microcystin-LR could affect renal physiology by altering vascular, glomerular and urinary parameters, indicating that MC-LR could act directly on the kidney. The aim of the current work was to examine the effect of MC-LR on mitochondrial oxidative phosphorylation of rat kidney isolated mitochondria.Furthermore, microcystin-LR decreased both state 3 and carbonylcyanide p-trifluoromethoxyphenylhydrazone (FCCP)-uncoupled respiration. The transmembrane potential was strongly depressed by MC-LR in a concentration dependent manner, pointing to an uncoupling effect; however, microcystin-LR did not increase the permeability of the inner mitochondria membrane to protons. Therefore, the transmembrane decrease was a consequence of a strong inhibitory effect on redox complexes. The addition of uncoupling concentrations of MC-LR to Ca(2+)-loaded mitochondria treated with ruthenium red resulted in mitochondrial permeability transition pore (MPTP) opening, as evidenced by mitochondrial swelling in isosmotic sucrose medium. Mitochondrial swelling in the presence of Ca(2+) was prevented by cyclosporin A and was drastically inhibited by catalase and dithiothreitol, indicating the participation of mitochondrial generated reactive oxygen species in this process. From this study it can be concluded that the bioenergetic lesion promoted by microcystin-LR seems to be sufficient to explain renal injury.

Topics: Adenosine Triphosphatases; Animals; Electron Transport Complex IV; Kidney Diseases; Male; Marine Toxins; Membrane Potential, Mitochondrial; Microcystins; Mitochondria; Mitochondrial Proton-Translocating ATPases; Mitochondrial Swelling; Rats; Rats, Wistar; Succinate Cytochrome c Oxidoreductase; Succinate Dehydrogenase

Topics: Animals; Carcinogens; Chemical and Drug Induced Liver Injury; Cyanobacteria; Dietary Supplements; Eukaryota; Food Contamination; Kidney Diseases; Liver Neoplasms; Marine Toxins; Maximum Allowable Concentration; Mice; Microcystins; Microcystis; Mutagens; Rats

Microcystin-LR (MCLR) is a cyanobacterial hepatotoxin that inhibits protein phosphatases 1 and 2A. To characterize cytoskeletal changes over time, hepatocytes were incubated with the toxin at 13.3 microM for 0, 2, 4, 6, 8, 16, 32, or 64 minutes. Changes in the hepatocytes were compared to those in cultured kidney cells and skin fibroblasts incubated with the toxin at 133 microM for 0, 2, 4, 8, 12, 16, or 24 hours. Cells were fixed and incubated with rhodamine-conjugated phalloidin, or primary antibodies against beta-tubulin and either vimentin or cytokeratin intermediate filaments (IFs), followed by fluorescein-conjugated secondary antibodies. The number of affected cells per 400 counted (NAC) with alterations in a specific cytoskeletal element were determined at each time point. In fibroblasts as well as kidney cells, changes occurred first in IFs, followed by microtubules (MTs), and later microfilaments (MFs). In some hepatocytes, IFs were affected first, but after 16 minutes, the NAC with altered MTs exceeded the NAC with alterations in other cytoskeletal elements. In both hepatocytes and non-hepatocytes, IFs and MTs condensed and collapsed around the nucleus. MFs similarly collapsed, but some of the actin radiated outward, producing a star-like appearance. The similarity of the cytoskeletal changes induced by MCLR in hepatocytes and non-hepatocytes suggests a common mechanism of action. Differences among cell types in sequential cytoskeletal alterations may be due to differences in phosphorylation of intracellular proteins.

Topics: Actin Cytoskeleton; Animals; Cells, Cultured; Cyanobacteria; Cytoskeleton; Enzyme Inhibitors; Fibroblasts; Intermediate Filaments; Kidney; Kidney Diseases; Liver; Male; Marine Toxins; Microcystins; Microtubules; Peptides, Cyclic; Rats; Rats, Sprague-Dawley