Hepatocyte-derived extracellular vesicles miR-122-5p promotes hepatic ischemia reperfusion injury by regulating Kupffer cell polarization

Ischemia reperfusion injury remains a major barrier to liver transplantation, especially using grafts from donation after circulatory death, and it is also a pressing issue to be solved in clinical practice. Kupffer cell polarization toward a proinflammatory M1 phenotype is an early trigger of liver ischemia-reperfusion injury. However, the molecular mechanism regulating Kupffer cell polarization has not yet been fully elucidated. We induced liver ischemia reperfusion injury in mice and obtained samples from patients undergoing liver transplantation, serum and hepatocytes-derived extracellular vesicles were isolated by differential ultracentrifugation. Kupffer cell polarization was examined by flow cytometry and immunofluorescence histochemistry. RNA-seq was conducted to detect the differentially expressed miRNAs in extracellular vesicles. The role and mechanism of exosomal miR-122-5p in liver ischemia-reperfusion injury were determined both in vitro and in vivo. We identified ischemia reperfusion induced extracellular vesicles as a major cause of hepatic inflammation and tissue damage using adoptive transfer and release inhibition. The study also demonstrated that hepatocyte-derived exosomal miR-122-5p mediates liver ischemia reperfusion injury by polarizing Kupffer cell via PPARδ down-regulation and NF-κB pathway activation using profiling and functional analysis. Moreover, inhibiting miR-122-5p with antagomir suppressed Kupffer cell M1 polarization and attenuated liver ischemia reperfusion injury. Overall, our study demonstrated that hepatocyte-derived exosomal miR-122-5p played a critical role in promoting hepatic ischemia reperfusion injury through modulating PPARδ signaling and NF-κB pathway to introduce M1 polarization of Kupffer cell. Inhibition of miR-122-5p exhibited a protective effect against liver ischemia reperfusion injury, suggesting a potential therapeutic target for liver transplantation.