Methotrexate-induced hepatotoxicity-mechanism, clinical cases and treatment approaches

Methotrexate (MTX) is a class of antifolate chemotherapeutics and immunosuppressants that are effectively used in the treatment regimen of cancer and autoimmune diseases. In the current MASLD era, methotrexate-induced hepatotoxicity must be understood in the context of host metabolic dysfunction, obesity, diabetes, and alcohol use that amplify oxidative and inflammatory liver injury. But its administration is being restricted due to hepatic toxicity, which increases asymptomatic in transaminases and progresses to fibrosis. This review examines the complex mechanisms underlying MTX-induced liver damage, including oxidative stress, mitochondrial impairment, inflammatory signaling pathways such as NF-κB and JAK/STAT, and apoptosis. Factors such as total dosage, genetic variations such as MTHFR polymorphism, concurrently used hepatotoxicity medication, and existing metabolic conditions significantly influence liver injury. Diagnostic methods, including transient elastography and non-invasive fibrosis indicators, modify the liver monitoring. New non-invasive biomarkers and genetic tests open opportunities for early identification. Treatment with folinic acid, antioxidants (silymarin and Vitamin E), and glucarpidase shows potential to reduce hepatic toxicity. Furthermore, therapeutic drug monitoring and lifestyle changes may enhance the safety. A comprehensive understanding of MTX-induced liver toxicity is essential for tailoring individualized treatment plans. This review differentiates between low-dose methotrexate used in autoimmune diseases and high-dose methotrexate used in oncology, emphasizing mechanistic differences in hepatotoxicity pathways, integrating MASLD-related risk factors, and summarizing current non-invasive diagnostic strategies. Further studies are required to understand the molecular targets involved in methotrexate- induced hepatotoxicity, as well as to translate into therapeutic approaches.

The above scientific illustration shows that, after intracellular polyglutamylation, Methotrexate induces oxidative stress in hepatocytes. This oxidative stress disrupts mitochondrial regulation and activates vital inflammatory signaling pathways, such as NF-κB and JAK/STAT. As a result, hepatic inflammation and apoptosis, along with the release of tumor necrosis factor-α, play a vital role in the progression of liver fibrosis. Potential therapeutic interventions, such as folinic acid and antioxidant therapy, have been identified as promising strategies to counteract MTX-induced hepatotoxicity (Created by BioRender.com).