Development of a novel mouse model of amodiaquine-induced liver injury with a delayed onset

Abstract

Amodiaquine (AQ) treatment is associated with a high incidence of idiosyncratic drug-induced liver injury (IDILI) and agranulocytosis. Evidence suggests that AQ-induced IDILI is immune mediated. A significant impediment to mechanistic studies of IDILI is the lack of valid animal models. This study reports the first animal model of IDILI with characteristics similar to mild IDILI in humans. Treatment of female C57BL/6 mice with AQ led to liver injury with delayed onset, which resolved despite continued treatment. Covalent binding of AQ was detected in the liver, which was greater in female than in male mice, and higher in the liver than in other organs. Covalent binding in the liver was maximal by Day 3, which did not explain the delayed onset of alanine aminotransferase (ALT) elevation. However, coincident with the elevated serum ALT, infiltration of liver and splenic mononuclear cells and activation of CD8 T-cells within the liver were identified. By Week 7, when ALT levels had returned close to normal, down-regulation of several inflammatory cytokines and up-regulation of PD-1 on T-cells suggested induction of immune tolerance. Treatment of Rag1 À/À mice with AQ resulted in higher ALT activities than C57BL/6 mice, which suggested that the adaptive immune response was responsible for immune tolerance. In contrast, depletion of NK cells significantly attenuated the increase in ALT, which implied a role for NK cells in mild AQ-induced IDILI. This is the first example of a delayed-onset animal model of IDILI that appears to be immune-mediated.

The chemical, genetic and immunological basis of idiosyncratic drug–induced liver injury

“…However, much more extensive studies with other drugs are needed. 84,85 A variety of different genetic polymorphisms associated with iDILI suggests the involvement of a wide variety of toxicological mechanisms. However, the number of the HLA associations discovered and the recent data on T-cells implies that immunological mechanisms play a critical role in the aetiology of iDILI.…”

Treatment of PD‐1−/− mice with amodiaquine and anti‐CTLA4 leads to liver injury similar to idiosyncratic liver injury in patients

“…Recently, we reported a novel mouse model of liver injury in which treatment of female C57BL/6 mice with amodiaquine (AQ) resulted in mild liver injury with a delay in onset that resolved despite continued treatment . AQ has been withdrawn from the market due to severe liver injury and agranulocytosis .…”

Effects of immunization and checkpoint inhibition on amodiaquine-induced liver injury

“…Amodiaquine (AQ) (Ipca Laboratories Ltd., Mumbai, India) was thoroughly mixed with rodent meal (2018 Teklad Global 18% Protein Diet, Envigo; Mississauga, ON, Canada) at a concentration of 0.2% (w/w) then provided in small jars ad libitum. This AQ dose has been shown to produce serum concentrations of 250-300 ng/ml in female mice, which is within the range of 80-800 ng/ml seen in humans (Metushi et al 2014). …”

“…Amodiaquine (AQ), which causes idiosyncratic druginduced liver injury in humans, was found to cause mild delayed-onset immune-mediated liver injury in mice that resolves despite continued treatment with the drug (Metushi et al 2014). In general, drugs that can cause serious IDILI more often result in mild injury that resolves despite continued treatment.…”