Methotrexate-Induced Liver Injury Is Associated with Oxidative Stress, Impaired Mitochondrial Respiration, and Endoplasmic Reticulum Stress In Vitro

Abstract

Low-dose methotrexate (MTX) is a standard therapy for rheumatoid arthritis due to its low cost and efficacy. Despite these benefits, MTX has been reported to cause chronic drug-induced liver injury, namely liver fibrosis. The hallmark of liver fibrosis is excessive scarring of liver tissue, triggered by hepatocellular injury and subsequent activation of hepatic stellate cells (HSCs). However, little is known about the precise mechanisms through which MTX causes hepatocellular damage and activates HSCs. Here, we investigated the mechanisms leading to hepatocyte injury in HepaRG and used immortalized stellate cells (hTERT-HSC) to elucidate the mechanisms leading to HSC activation by exposing mono- and co-cultures of HepaRG and hTERT-HSC to MTX. The results showed that at least two mechanisms are involved in MTX-induced toxicity in HepaRG: (i) oxidative stress through depletion of glutathione (GSH) and (ii) impairment of cellular respiration in a GSH-independent manner. Furthermore, we measured increased levels of endoplasmic reticulum (ER) stress in activated HSC following MTX treatment. In conclusion, we established a human-relevant in vitro model to gain mechanistical insights into MTX-induced hepatotoxicity, linked oxidative stress in HepaRG to a GSH-dependent and -independent pathway, and hypothesize that not only oxidative stress in hepatocytes but also ER stress in HSCs contribute to MTX-induced activation of HSCs.

Silibinin’s Effects against Methotrexate-Induced Hepatotoxicity in Adjuvant-Induced Arthritis Rat Model

“…Methotrexate (MTX) is known to have adverse effects on the liver’s antioxidant defense mechanism. It can increase the production of toxic by-products such as reactive oxygen species (ROS) and inhibit the cofactors of several antioxidant enzymes [ 42 , 43 , 44 ]. This reduction in the activities of protective antioxidant enzymes such as SOD, CAT, and non-enzymatic GSH can cause a surge in lipid peroxidation ( Figure 9 B).…”

Protective Effects of Crocin Against Methotrexate-Induced Hepatotoxicity in Adult Male Albino Rats: Histological, Immunohistochemical, and Biochemical Study

“…TGF-β1 , a cytokine that promotes fibrosis, enhances collagen synthesis and deposition of extracellular matrix and can stimulate the transformation of hepatic stellate cells to myofibroblast [ 32 ]. It has been reported that TGF-β1 regulates the mitogen-activated protein kinase (MAPK) signaling and suppressor of mothers against decapentaplegic homolog 2/3 ( SMAD2/3 ) pathways to drive stellate cell activation [ 33 ]. Additionally, inhibiting the TGF-β1 signaling pathway can possibly interrupt the advancement of liver disease [ 34 ].…”

DNA polymerase gamma variants and hepatotoxicity during maintenance therapy of childhood acute lymphoblastic leukemia: is there a causal relationship?

“…MTX has been shown to impair mitochondrial respiratory chain function [7]. In addition, oxidative stress caused by increased reactive oxygen species (ROS) and reduced glutathione levels may be a mechanism for MTX-induced mitochondrial toxicity [28][29][30]. MTX-induced impairment of the mitochondrial respiratory chain leads to reduced fatty acid oxidation and increased fatty acid accumulation (i.e., macrovacuolar steatosis), thus resulting in drug-induced hepatic steatosis [7].…”

“…Non-alcoholic steatohepatitis (NASH) has been observed in liver biopsies of patients with rheumatoid arthritis receiving low doses of oral MTX, although those patients had additional risk factors for NASH [ 31 ]. A recent study showed that therapeutic levels of low-dose MTX resulted in the accumulation of ROS and impairment of the mitochondrial respiratory chain on human hepatoma and hepatic stellate cells [ 30 ]. VPA-induced liver failure associated with POLG1 variants usually requires 2–3 months of VPA administration, ranging from 4 to 26 weeks, before the onset of symptoms [ 25 , 32 , 33 ].…”