*Purpose: Successful orthotopic liver transplantation (OLT) surgery mostly depends on good and functional liver donor, besides of mature transplant technology. The molecular basis of different liver donor with distinct susceptibility to ischemia/reperfusion (I/R) injury during liver transplantation remains undefined. Using isobaric tags for relative and absolute quantification (iTRAQ), we investigated proteomic alterations during early graft reperfusion in human liver transplantation.

*Methods: Liver transplant clinical data were compiled from November 2015 to December 2017 at the First Affiliated Hospital of Sun Yat-sen University, China. Liver tissue samples were acquired from 15 donor livers, which belongs to three groups: optimal graft function (OGF), early allograft dysfunction (EAD), primary nonfunction (PNF). Each pair biopsy was taken before anhepatic phase and at the end of transplantation. Liver samples obtained at the start of the retrieval operation were set up as normal control group. Comparative quantitative proteomics was performed to find differential promoetic among OGF, EAD, PNF and control group. Label-free LC−MRM-MS-based targeted method was further emploied for verification. MRM analyses were performed on a QTRAP5500 mass spectrometer equipped with LC-20AD nanoHPLC system.

*Results: A total of 6505 proteins were preliminarily identified in the human liver donor. As for the data of comparative quantitative proteomics, 1139 proteins were expressed differentially between those tissue group. As for the the comparison of ischemia reperfusion injury related proteins, 318 proteins were identified to be expressed differentially compared to normal control group. 22 proteins play a centrol role in the IRI injury process. However, a higher uniformity was noted in the PNF group. More than 160 differentially expressed proteins were detected in PNF group, compared to 54 and 36 proteins in the EAD and OGF groups respectively. The molecular function of these proteins were mainly involved in catalytic activity, binding, antioxidant activity, transporter, structual molecule, receptor, molecular transducer, enzyme regulator, electron carrier. Further verification test demonstrated that 103 proteins could feasible for MRM analysis, and 57 proteins were finally verified among those groups. 15 proteins were verified to be related to IRI injury, including decreased expression of CNDP2, PRDX1, HGD, FABPL, THIO, 6PGD, HPPD in PNF group.

*Conclusions: This study uncovered new insights into graft function related protein in liver allograft. Several significantly altered protein expressions were found in PNF group. Dysfunctional liver donor is more sensible to IRI injury companied with more protein changes in biological process and molecular function. The present findings might provide new avenues for evaluation of liver allograft quality.

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