In vivo upstream factors of mouse hepatotoxic mechanism with sustained hepatic glutathione depletion: Acetaminophen metabolite-erythrocyte adducts and splenic macrophage-generated reactive oxygen species

Tadatoshi Tanino ¹, Yukari Ueda ¹, Noriaki Nagai ²

⁰Faculty of Pharmaceutical Sciences, Tokushima Bunri University, 180 Bouji Nishihama, Yamashiro-cho, Tokushima, 770-8514, Japan.

Chemico-Biological Interactions +

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June 2, 2024

View abstract on PubMed

Summary

The spleen is critical for acetaminophen-induced liver damage, as splenic macrophages engulf drug-adducts, leading to oxidative stress and liver injury. Spleen removal significantly protects against this damage.

Area Of Science

Hepatology
Immunology
Toxicology

Background

Acetaminophen (APAP) overdose causes liver damage via reactive oxygen species (ROS) and ferroptosis.
The role of splenic macrophages and erythrocyte interactions in APAP hepatotoxicity remains unclear.

Purpose Of The Study

To investigate the upstream mechanisms of APAP-induced liver damage, focusing on splenic macrophage phagocytosis of APAP-erythrocyte adducts.
To explore the role of the spleen in APAP hepatotoxicity in vivo.

Main Methods

Splenectomy was performed on mice prior to APAP administration.
Mice were treated with APAP, a redox probe (DCFH-DA), macrophage-depleting clodronate (CL), and a NOX2 inhibitor.
Hepatic cytochrome P450 (CYP) 2E1 activity, hepatic glutathione (GSH) content, plasma alanine aminotransferase levels, and hepatic necrosis were assessed.
APAP-erythrocyte adducts, splenic ferrous iron levels, and ROS production were measured.

Main Results

Splenectomy significantly protected against APAP-induced liver injury, reducing ALT levels and necrosis.
APAP treatment led to increased ROS around splenic macrophages and elevated splenic ferrous iron.
Splenic macrophages engulfed APAP-erythrocyte adducts, contributing to GSH depletion and erythrocyte deformation.
Co-treatment with DCFH-DA, CL, NOX2 inhibitor, and CYP inhibitor ameliorated liver damage and restored GSH levels.

Conclusions

Splenic macrophages play a critical role in APAP hepatotoxicity by phagocytosing APAP-erythrocyte adducts.
This process triggers ROS production in the spleen, leading to hepatic GSH depletion and liver damage.
Targeting splenic mechanisms represents a potential therapeutic strategy for APAP overdose.

Keywords:

Acetaminophen liver damage Erythrocyte-metabolite adducts Phagocytic reactive oxygen species Splenic macrophages Sustained hepatic reduced glutathione depletion