Peptidomic Analysis Reveals that Novel Peptide LDP2 Protects Against Hepatic Ischemia/Reperfusion Injury

Background and Aims: (I/R) injury has become an inevitable issue during liver transplantation, with no effective treatments available. However, peptide drugs provide promising regimens for the treatment of this injury and peptidomics has gradually attracted increasing attention. This study was designed to analyze the spectrum of peptides in injured livers and ex-plore the potential beneficial peptides involved in I/R injury. Methods: C57BL/6 mice were used to establish a liver I/R injury animal model. Changes in peptide profiles in I/R-in-jured livers were analyzed by mass spectrometry, and the functions of the identified peptides were predicted by bio-informatics. AML12 cells were used to simulate hepatic I/R injury in vitro. After treatment with candidate liver-derived peptides (LDPs) 1-10, the cells were collected at various reperfusion times for further study. Results: Our prelimi-nary study demonstrated that 6 h of reperfusion caused the most liver I/R injury. Peptidomic results suggested that 10 down-regulated peptides were most likely to alleviate I/R injury by supporting mitochondrial function. Most impor-tantly, a novel peptide, LDP2, was identified that alleviated I/R injury of AML12 cells. It increased cell viability and re-duced the expression of inflammation-and apoptosis-relat-ed proteins. In addition, LDP2 inhibited the expression of proteins related to autophagy. Conclusions: Investigation of changes in the profiles of peptides in I/R-injured livers led to identification of a novel peptide, LDP2 with potential function in liver protection by inhibiting inflammation, apo-ptosis, and autophagy.