This research study has major implications for the development of ESH as a safe and holistic hepatoprotectant and could be used as an adjuvant in the treatment of IBD to minimize DILI. We demonstrate that ESH regulates oxidative stress, NIK/NF-κB-mediated inflammatory axis, and improves the hepatocellular integrity against AZA-provoked deleterious events in the hepatocytes (Figure 5). However, further research is warranted to elucidate the efficacy, specificity, and safety of ESH in AZA-treated patients with normal genetic makeup and gene polymorphisms.

Hepatotoxicity is one of the well-documented adverse effects of azathioprine (AZA), a linchpin in the immunosuppressant regimen in the treatment of various autoimmune diseases. In this study, L-Ergothioneine (ESH)—a unique thiol/thione amino acid—was investigated for its putative antioxidant and hepatocyte protective properties against AZA by using HepaRG liver cell model. The effect of ESH on AZA metabolizing enzymes (xanthine oxidase (XO) and glutathione S-transferase (GST) M1), reactive oxygen species (ROS) and glutathione (GSH) levels, mitochondrial parameters (ATP, succinate, and mitochondrial membrane potential) and upstream signaling parameters including SIRT1-mediated antioxidant genes (Nrf2, HO1, and γ-GCLC) were assessed. AZA exposure provoked XO and GST-M1-mediated ROS production and GSH depletion, mitochondrial dysfunction, and downregulation of SIRT1-Nrf2 axis and ultimately resulted in hepatocellular toxicity. ESH treatment effectively counteracted these aberrations and preserved the hepatocellular viability and functions. The present study demonstrated that ESH attenuates AZA-induced oxidative stress and mitochondrial dysfunction via suppression of AZA metabolizing enzymes and upregulation of SIRT1-Nrf2 signaling.