The α-ketoglutarate (αKG), a metabolite of glutaminolysis, is reported to orchestrate macrophages activation. This study aims to clarify whether the αKG / glutaminolysis metabolism can suppress Kupffer cells (KCs) activation during liver transplantation and attenuate hepatic ischemia-reperfusion injury (IRI).

Donor livers were perfused with DM-αKG (a cell-permeable analog of αKG) or BPTES (an inhibitor of glutaminase 1) via portal vein during cold preservation, and controls were perfused with UW solution. Then, a rat model of liver transplantation was performed. Serum levels of alanine transaminase (ALT), total bilirubin (TBIL) and inflammatory cytokines, as well as histology, were analyzed after 24 h. KCs were isolated from grafts. RT-PCR and immunofluorescence were used to evaluate polarization-specific marker genes. Western bolt was employed to assess the expression of phosphorylation of glycogen synthase kinase 3β (p-GSK3β) and suppressor of cytokine signaling 1 (SOCS1). EMSA was utilized to quantify the NF-κB transcriptional activity.

Compared with controls, DM-αKG perfusion decreased ALT and TBIL levels, alleviated liver damage, and reduced apoptosis, while BPTES group showed higher ALT and TBIL levels, severe damage and more apoptosis. Furthermore, DM-αKG perfusion suppressed NF-κB activity, up-regulated the expression of p-GSK3β and SOCS1 in KCs, and shifted the M1/M2 balance toward an anti-inflammatory profile. Besides, DM-αKG suppressed serum pro-inflammatory cytokines secretion and increased IL-10.

αKG produced by glutaminolysis protects liver graft from IRI by regulating the inflammatory response and modifying the polarization of KCs.