IRE1α aggravates ischemia reperfusion injury of fatty liver by regulating phenotypic transformation of kupffer cells

Fatty liver is one of the widely accepted marginal donor for liver transplantation, but is also more sensitive to ischemia and reperfusion injury (IRI) and produces more reactive oxygen species (ROS). Moreover, so far, no effective method has been developed to alleviate it. Endoplasmic reticulum stress (ER-stress) of hepatocyte is associated with the occurrence of fatty liver disease, but ER-stress of kupffer cells (KCs) in fatty liver is not clear at all. This study evaluates whether ER-stress of KCs is activated in fatty liver and accelerate IRI of fatty livers. ER-stress of KCs was activated in fatty liver, especially the IREla signal pathway. KCs with activated ER-stress secreted more proinflammatory cytokine to induce its Ml-phenotypic shift in fatty liver, resulting in more severe IRI. Also, activated ER-stress of BMDMs in vitro by tunicamycin can induce its pro-inflammatory shift and can be reduced by 4-PBA, an ER-stress inhibitor. Knockdown of IRE1 alpha could regulate the STAT1 and STAT6 pathway of macrophage to inhibit the Ml-type polarization and promote M2-phenotypic shift. Furthermore, transfusion of IRE1 alpha-knockdown KCs significantly reduced the liver IRI as well as the ROS of HFD feeding mice. Altogether, these data demonstrated that IRE1 alpha of KCs may be a potential target to reduce the fatty liver associated IRI in liver transplantation.