CO-PERK-IRG1 axis attenuates oxidative stress and ferroptosis in hepatic ischemia-reperfusion injury

Hepatic ischemia-reperfusion injury (IRI) can arise as the consequence of surgical procedures, including liver transplant. Hepatic IRI is characterized by oxidative stress, inflammation, and activation of multiple regulated cell death pathways (RCD). Among RCD, ferroptosis is driven by enhanced lipid peroxidation and reactive oxygen species (ROS) formation. Carbon monoxide (CO), which can exert cytoprotective and anti-inflammatory properties, can mitigate IRI in various pre-clinical models when applied at low concentration, though the underlying mechanisms remain poorly understood. In this study, we describe a critical role of protein kinase RNA-like endoplasmic reticulum kinase (PERK) signaling in the protective effects of CO against oxidative stress and ferroptosis. We demonstrate that CO-induced PERK activation phosphorylates Nrf2, a master regulator of the cellular antioxidant response, leading to upregulation of immune-responsive gene 1 (IRG1) expression in both Kupffer cells (KCs) and hepatocytes. IRG1-derived itaconate production suppressed ROS accumulation and ferroptosis by enhancing GPX4 levels, while reducing ACSL4 and PTGS2 expression. Genetic interference of PERK or Nrf2 using siRNA or knockout mice abolished CO-mediated IRG1 induction and protection against ferroptosis, highlighting the indispensable role of this pathway. Furthermore, in an in vivo model of hepatic IRI, CO treatment significantly reduced inflammation, histopathological damage, and ferroptosis in a manner dependent on the PERK-Nrf2-IRG1 axis. These findings establish the PERK-Nrf2-IRG1-itaconate pathway as a novel therapeutic target for hepatic IRI and potentially other ferroptosis-driven conditions.