Effects of resveratrol on alpha-amanitin-induced nephrotoxicity in BALB/c mice

α-Amanitin aggravates hepatic injury by activating oxidative stress and mitophagy via peroxiredoxin 6 inhibition

Mushroom poisoning is mainly caused by α-amanitin (α-AMA), and there is currently no effective drug to treat α-AMA poisoning. Therefore, it is particularly important to find early diagnostic markers for α-AMA injury. Hepatic injury models induced by α-AMA were established both in hepatic cells and mice. The cell viability of human normal hepatic cells after α-AMA treatment was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Liver function parameters was assessed by the Enzyme-Linked Immunosorbent Assay (ELISA). Furthermore, oxidative stress was detected by 2',7'-Dichlorofluorescin Diacetate (DCFH-DA) and Dihydroethidium (DHE) staining. Autophagy- and apoptosis-related proteins were assessed by Western blot and immunofluorescence staining. We applied Hematoxylin and Eosin (H&E), Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and Oil Red O (ORO) staining to observe the degree of cell damage and hepatocyte apoptosis. In addition, mitochondrial membrane potential was also determined by JC-1 immunofluorescence staining and flow cytometry. The results showed that α-AMA decreased cell viability in a dose-dependent manner. In addition, the levels of alanine aminotransferase (ALT), aspartate transaminase (AST) and mitochondrial reactive oxygen species (mtROS) were observed to increase in the α-AMA-treated groups, whereas antioxidants superoxide dismutase (SOD) levels were reduced. Moreover, α-AMA promoted hepatocyte mitophagy and apoptosis, which were alleviated by PRDX6 overexpression. Finally, PRDX6 and Parkin were found to accumulate in mitochondria and α-AMA activated mitophagy by silencing PRDX6. Collectively, our results demonstrated that α-AMA activates oxidative stress and mitophagy by inhibiting the expression of PRDX6, leading to hepatic injury. These findings from both in vitro and in vivo models provide insights into the toxicological mechanisms of α-AMA, underscoring the potential of PRDX6 as a therapeutic target for treating α-AMA-induced hepatotoxicity. HIGHLIGHTS: α-AMA leads to ROS accumulation and activates oxidative stress. α-AMA promotes hepatocyte mitophagy and apoptosis. PRDX6 alleviates α-AMA-induced hepatic injury. PRDX6 mediates mitophagy through Parkin.

Detection and quantification of Amatoxin in wild mushrooms from North-East India using HPLC-PDA method for food safety purposes

Misidentification and ingestion of poisonous mushrooms pose significant threats to food safety, particularly in Mizoram, India, where over ten fatalities due to mushroom poisoning have been reported in the past decade (2013-2023). This study aimed to address this critical issue by identifying and quantifying the cause of death due to consumption of wild mushroom from Champhai district, Mizoram, India and to test the reliability of HPLC-PDA for detection and quantification of amatoxins. HPLC-PDA confirmed the presence of α-amanitin in Amanita virosa and Amanita bisporigera in the samples. α-amanitin is a water-soluble, heat-stable, and highly toxic cyclic octapeptide present in the genus Amanita, which includes Amanita phalloides, Amanita verna, and Amanita virosa. Amanitin cytotoxicity arises from the inhibition of RNA polymerases, namely RNA polymerase II, which obstructs mRNA production in kidney and liver cells. Validation of the method demonstrated good precision and accuracy, with LOD and LOQ values of 88 ng g-1 and 210 ng g-1, respectively. The method was successfully applied to quantify α-amanitin in ten wild mushroom samples, revealing its presence only in Amanita virosa (1.17 mg g-1) and Amanita bisporigera (1.91 mg g-1) species. These findings underscore the importance of accurate α-amanitin detection methods in ensuring food safety and public health, particularly in regions prone to mushroom poisoning incidents. It is noteworthy that this study marks the initial exploration for detection and quantification of α-amanitin from poisonous mushrooms found in the wild regions of Champhai district in Mizoram, representing the first report of such in the area.

β-carotene protects against α-amanitin nephrotoxicity via modulation of oxidative, autophagic, nitric oxide signaling, and polyol pathways in rat kidneys

Alpha-amanitin (α-AMA), a toxic component of Amanita phalloides, causes severe hepato- and nephrotoxicity. This study investigated the protective effects of βeta-carotene (βC) against α-AMA-induced kidney damage in rats. Thirty-two male Sprague-Dawley rats were divided into four groups: Control, βC (50 mg/kg/day), α-AMA (3 mg/kg), and βC+α-AMA. βC was administered orally for 7 days before α-AMA injection. Renal function, oxidative stress markers, histopathological changes, and enzyme activities were evaluated 48 h post-α-AMA administration. α-AMA significantly increased serum creatinine and urea levels, decreased glutathione and catalase activity, and increased malondialdehyde levels (P < 0.001). βC pretreatment attenuated these changes (P < 0.05). Histopathological examination revealed reduced tubular degeneration in the βC+α-AMA group (P < 0.001). Immunohistochemical analysis showed increased LC3B and Beclin-1 expression in α-AMA-treated rats, indicating enhanced autophagy, partially reversed by βC. Additionally, α-AMA reduced nitric oxide synthase (NOS) activity and increased aldose reductase (AR) activity, both normalized by βC pretreatment (P < 0.01). βC demonstrates protective effects against α-AMA-induced nephrotoxicity through antioxidant action, modulation of autophagy, and regulation of NOS and AR pathways, suggesting its potential as a therapeutic agent in α-AMA poisoning.

Integrating genome-wide CRISPR screens and in silico drug profiling for targeted antidote development

Numerous toxins threaten humans, but specific antidotes are unavailable for most of them. Although CRISPR screening has aided the discovery of the mechanisms of some toxins, developing targeted antidotes remains a significant challenge. Recently, we established a systematic framework to develop antidotes by combining the identification of novel drug targets by using a genome-wide CRISPR screen with a virtual screen of drugs approved by the US Food and Drug Administration. This approach allows for a comprehensive understanding of toxin mechanisms at the whole-genome level and facilitates the identification of promising antidote drugs targeting specific molecules. Here, we present step-by-step instructions for executing genome-scale CRISPR-Cas9 knockout screens of toxins in HAP1 cells. We also provide detailed guidance for conducting an in silico drug screen and an in vivo drug validation. By using this protocol, it takes ~4 weeks to perform the genome-scale screen, 4 weeks for sequencing and data analysis, 4 weeks to validate candidate genes, 1 week for the virtual screen and 2 weeks for in vitro drug validation. This framework has the potential to accelerate the development of antidotes for a wide range of toxins and can rapidly identify promising drug candidates that are already known to be safe and effective. This could lead to the development of new antidotes much more quickly than traditional methods, protecting lives from diverse toxins and advancing human health.

Amanitin-induced variable cytotoxicity in various cell lines is mediated by the different expression levels of OATP1B3

Amanita phalloides is one of the deadliest mushrooms worldwide, causing most fatal cases of mushroom poisoning. Among the poisonous substances of Amanita phalloides, amanitins are the most lethal toxins to humans. Currently, there are no specific antidotes available for managing amanitin poisoning and treatments are lack of efficacy. Amanitin mainly causes severe injuries to specific organs, such as the liver, stomach, and kidney, whereas the lung, heart, and brain are hardly affected. However, the molecular mechanism of this phenomenon remains not understood. To explore the possible mechanism of organ specificity of amanitin-induced toxicity, eight human cell lines derived from different organs were exposed to α, β, and γ-amanitin at concentrations ranging from 0.3 to 100 μM. We found that the cytotoxicity of amanitin differs greatly in various cell lines, among which liver-derived HepG2, stomach-derived BGC-823, and kidney-derived HEK-293 cells are most sensitive. Further mechanistic study revealed that the variable cytotoxicity is mainly dependent on the different expression levels of the organic anion transporting polypeptide 1B3 (OATP1B3), which facilitates the internalization of amanitin into cells. Besides, knockdown of OATP1B3 in HepG2 cells prevented α-amanitin-induced cytotoxicity. These results indicated that OATP1B3 may be a crucial therapeutic target against amanitin-induced organ failure.

Biodistribution of radiolabeled alpha-amanitin in mice: An Investigation

Mushroom poisonings caused by Amanita phalloides are the leading cause of mushroom-related deaths worldwide. Alpha-Amanitin (α-AMA), a toxic substance present in these mushrooms, is responsible for the resulting hepatotoxicity and nephrotoxicity. The objective of our study was to determine the distribution of α-AMA in Balb/c mice by labeling with Iodine-131. Mice were injected with a toxic dose (1.4 mg/kg) of α-AMA labeled with Iodine-131. The mice were sacrificed at the 1st, 2nd, 4th, 8th, 24th, and 48th hours under anesthesia. The organs of the mice were removed, and their biodistribution was assessed in all experiments. The percent injected dose per gram (ID/g %) value for kidney, liver, lung, and heart tissues at 1st hour were 1.59 ± 0.07, 1.25 ± 0.33, 3.67 ± 0.80 and 1.07 ± 0.01 respectively. This study provides insights into the potential long-term effects of α-AMA accumulation in specific organs. Additionally, this study has generated essential data that can be used to demonstrate the impact of antidotes on the biological distribution of α-AMA in future toxicity models.

Amanitins in Wild Mushrooms: The Development of HPLC-UV-EC and HPLC-DAD-MS Methods for Food Safety Purposes

Mushroom poisoning remains a serious food safety and health concern in some parts of the world due to its morbidity and mortality. Identification of mushroom toxins at an early stage of suspected intoxication is crucial for a rapid therapeutic decision. In this study, a new extraction method was developed to determine α- and β-amanitin in mushroom samples collected from central Portugal. High-performance liquid chromatography with in-line ultraviolet and electrochemical detection was implemented to improve the specificity of the method. The method was fully validated for linearity (0.5-20.0 µg·mL^-1), sensitivity, recovery, and precision based on a matrix-matched calibration method. The limit of detection was 55 µg mL^-1 (UV) and 62 µg mL^-1 (EC) for α-amanitin and 64 µg mL^-1 (UV) and 24 µg mL^-1 (EC) for β-amanitin. Intra- and inter-day precision differences were less than 13%, and the recovery ratios ranged from 89% to 117%. The developed method was successfully applied to fourteen Amanita species (A. sp.) and compared with five edible mushroom samples after extraction with Oasis^® PRIME HLB cartridges without the conditioning and equilibration step. The results revealed that the A. phalloides mushrooms present the highest content of α- and β-amanitin, which is in line with the HPLC-DAD-MS. In sum, the developed analytical method could benefit food safety assessment and contribute to food-health security, as it is rapid, simple, sensitive, accurate, and selectively detects α- and β-amanitin in any mushroom samples.

Antidotal effect of cyclosporine A against α-amanitin toxicity in CD-1 mice, at clinical relevant doses

Amanita phalloides is one of the most toxic mushrooms worldwide, being responsible for the majority of human fatal cases of mushroom intoxications. α-Amanitin, the most deleterious toxin of A. phalloides, inhibits RNA polymerase II (RNAP II), causing hepatic and renal failure. Herein, we used cyclosporine A after it showed potential to displace RNAP II α-amanitin in silico. That potential was not confirmed either by the incorporation of ethynyl-UTP or by the monitoring of fluorescent RNAP II levels. Nevertheless, concomitant incubation of cyclosporine A with α-amanitin, for a short period, provided significant protection against its toxicity in differentiated HepaRG cells. In mice, the concomitant administration of α-amanitin [0.45 mg/kg intraperitoneal (i.p.)] with cyclosporine A (10 mg/kg i.p. plus 2 × 10 mg/kg cyclosporine A i.p. at 8 and 12 h post α-amanitin) resulted in the full survival of α-amanitin-intoxicated mice, up to 30 days after the toxin's administration. Since α-amanitin is a substrate of the organic-anion-transporting polypeptide 1B3 and cyclosporine A inhibits this transporter and is a potent anti-inflammatory agent, we hypothesize that these mechanisms are responsible for the protection observed. These results indicate a potential antidotal effect of cyclosporine A, and its safety profile advocates for its use at an early stage of α-amanitin intoxications.