Study examines how COX-2 regulates ferroptosis in chronic liver injury

Background and aims

Ferroptosis plays an essential role in chronic liver diseases, and cyclooxygenase-2 (COX-2) affects liver fibrosis through multiple mechanisms. However, research on COX-2 regulation of ferroptosis in chronic liver injury remains limited. This study aimed to investigate whether and how COX-2 regulates ferroptosis in chronic liver injury.

Methods

In vivo, a thioacetamide (TAA)-induced chronic liver injury model, characterized by significant liver lipid peroxidation and oxidative stress, was used. COX-2^+/+ and COX-2^–/– mice were treated with TAA or normal saline. In vitro, primary mouse hepatocytes were isolated and treated with dimethyl sulfoxide (DMSO), erastin+DMSO, etoricoxib+erastin+DMSO, and tBHQ+erastin+DMSO. Mitochondrial morphology, iron metabolism, lipid peroxidation, and oxidative stress were assessed to verify ferroptosis. The nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway was measured to investigate the relationship between COX-2 and ferroptosis.

Results

TAA-treated COX-2^–/– mice presented milder liver fibrosis, whereas TAA-treated COX-2^–/– mice livers and etoricoxib+erastin+DMSO-treated primary hepatocytes exhibited alleviated mitochondrial damage compared with TAA-treated COX-2^+/+ littermates and erastin+DMSO-treated primary hepatocytes, respectively. The knockout of COX-2 decreased ferrous ion concentration (p < 0.01) and mitigated lipid peroxidation in TAA-treated livers (p < 0.05). Furthermore, both COX-2 knockout and etoricoxib restored reduced glutathione (p < 0.05) and glutathione peroxidase 4 (p < 0.05), while decreasing malondialdehyde levels (p < 0.05). Additionally, COX-2 inhibition upregulated Nrf2, which helped alleviate erastin+DMSO-induced ferroptosis (p < 0.01).

Conclusions

COX-2 plays a pivotal role in ferroptosis during the progression of chronic liver disease, as it downregulates the Nrf2 signaling pathway, exacerbating ferroptosis, which is characterized by ferrous ion overload, lipid peroxidation, and excessive oxidative stress. Inhibition of COX-2 has reliable effects in alleviating liver ferroptosis and fibrosis. In future clinical practice, selective COX-2 inhibitors may serve as a potential therapeutic modality to combat liver fibrosis via ferroptosis inhibition.