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Liver ischemia‐reperfusion injury (IRI) is an important factor affecting the prognosis of liver transplantation, and extended criteria donors (e.g., steatosis donor livers) are considered to be more sensitive to ischemia‐reperfusion injury in liver transplantation. Currently, the application of human umbilical cord mesenchymal stem cells (hMSCs) has great promise in the treatment of various injuries in the liver. This study aimed to investigate the therapeutic role and mechanism of hMSCs in fatty liver IRI. After more than 8 weeks of high‐fat chow feeding, we constructed a fatty liver mouse model and established ischemic injury of about 70% of the liver. Six hours after IRI, liver injury was significantly alleviated in hMSCs‐treated mice, and the expression levels of liver enzyme, inflammatory factor TNF‐α, and apoptotic proteins were significantly lower than those of the control group, which were also significant in pathological sections. Transcriptomics analysis showed that IFNγ was significantly upregulated in the hMSCs group. Mechanistically, IFNγ, which activates the MAPK pathway, is a potent agonist that promotes the occurrence of autophagy in hepatocytes to exert a protective function, which was confirmed by in vitro experiments. In summary, hMSCs treatment could slow down IRI in fatty liver by activating autophagy through upregulation of IFNγ, and this effect was partly direct. Significance statement: This study demonstrated the important therapeutic role of human umbilical cord mesenchymal stem cells (hMSCs) in fatty liver ischemia‐reperfusion injury (IRI) and elaborated the mechanism of IFNγ in activating autophagy and thus playing a protective role, which is of positive significance for the study of functional protection and enhancement of transplanted donor liver. [ABSTRACT FROM AUTHOR]

Background: Hepatic ischemia–reperfusion (IR) injury is the primary reason for complications following hepatectomy and liver transplantation (LT). Insulin-induced gene 2 (Insig2) is one of several proteins that anchor the reticulum in the cytoplasm and is essential for metabolism and inflammatory responses. However, its function in IR injury remains ambiguous. Methods: Insig2 global knock-out (KO) mice and mice with adeno-associated-virus8 (AAV8)-delivered Insig2 hepatocyte-specific overexpression were subjected to a 70% hepatic IR model. Liver injury was assessed by monitoring hepatic histology, inflammatory responses, and apoptosis. Hypoxia/reoxygenation stimulation (H/R) of primary hepatocytes and hypoxia model induced by cobalt chloride (CoCl2) were used for in vitro experiments. Multi-omics analysis of transcriptomics, proteomics, and metabolomics was used to investigate the molecular mechanisms underlying Insig2. Results: Hepatic Insig2 expression was significantly reduced in clinical samples undergoing LT and the mouse IR model. Our findings showed that Insig2 depletion significantly aggravated IR-induced hepatic inflammation, cell death and injury, whereas Insig2 overexpression caused the opposite phenotypes. The results of in vitro H/R experiments were consistent with those in vivo. Mechanistically, multi-omics analysis revealed that Insig2 is associated with increased antioxidant pentose phosphate pathway (PPP) activity. The inhibition of glucose-6-phosphate-dehydrogenase (G6PD), a rate-limiting enzyme of PPP, rescued the protective effect of Insig2 overexpression, exacerbating liver injury. Finally, our findings indicated that mouse IR injury could be attenuated by developing a nanoparticle delivery system that enables liver-targeted delivery of substrate of PPP (glucose 6-phosphate). Conclusions: Insig2 has a protective function in liver IR by upregulating the PPP activity and remodeling glucose metabolism. The supplementary glucose 6-phosphate (G6P) salt may serve as a viable therapeutic target for alleviating hepatic IR. [ABSTRACT FROM AUTHOR]