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

• Published in: Food and chemical toxicology Vol. 166; p. 113198
• Main Authors: Garcia, Juliana, Carvalho, Alexandra, das Neves, Ricardo Pires, Malheiro, Rui, Rodrigues, Daniela F., Figueiredo, Pedro R., Bovolini, Antonio, Duarte, José Alberto, Costa, Vera Marisa, Carvalho, Félix
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-08-2022
• Subjects: Cyclosporine A; HepaRG cells; HK-2 cells; Nascent RNA; RNA polymerase II; α-Amanitin; Cyclosporine A; HK-2 cells; Nascent RNA; HepaRG cells; α-Amanitin; RNA polymerase II; HK-2 cells
• ISSN: 0278-6915; 1873-6351
• DOI: 10.1016/j.fct.2022.113198

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.
•Cyclosporine A has a potential to displace α-amanitin from RNAP II in silico.•Cyclosporine A does not displace α-amanitin from RNAP II in vitro.•Brief concomitant incubation of cyclosporine A with α-amanitin protects differentiated HepaRG cells.•In mice, the concomitant use of cyclosporine A with α-amanitin leads to full survival.