In an effort to identify proteins involved in the disease process of acute liver failure (ALF), we investigated changes in the plasma proteome associated with d-galactosamine/lipopolysaccharide (GalN/LPS) treatment of BALB/c mice. The plasma samples from mice with ALF and control were screened for potential differences using two-dimensional electrophoresis followed by liquid chromatography−electrospray ionization−tandem mass spectrometry or matrix associated laser desorption ionization-time-of-flight mass spectrometry. The expression levels of candidate protein named phosphatidylethanolamine binding protein (PEBP) in plasma and liver, brain tissues were confirmed by western blot and RT-PCR analyses. Results were confirmed in plasma samples of human beings. Seven proteins existed in plasma of GalN/LPS-treatment animals only but not in controls. They included PEBP, regucalcin, Cu/Zn superoxide dismutase, glyoxalase 1, malate dehydrogenase, proteasome subunit alpha type 1, and HPMS haptoglobin precursor. Two proteins, proteasome subunit alpha type 5 and apolipoprotein A-I precursor, were up-regulated by GalN/LPS, and one protein, HPMS haptoglobin precursor, was down-regulated by this treatment. Western blot analysis confirmed the results that PEBP protein levels increased significantly in plasma and liver tissues only in ALF mice, but not in surviving mice treated with GalN/LPS. Further analysis revealed that GalN/LPS also induced up-regulation of PEBP mRNA levels in liver tissues. Importantly, plasma obtained from ALF patients, but not from healthy volunteers or from hepatitis patients, also contained detectable levels of PEBP. The present study show that PEBP may be a potential plasma biomarker for ALF diagnosis and participate in the pathphysiological process of ALF.

Keywords: proteomics • phosphatidylethanolamine binding protein • d-galactosamine • lipopolysaccharide • two-dimensional electrophoresis