Hemoglobin beta chain fragments in bile correspond with restoration of liver function early after liver transplantation

The visual evaluation of bile after liver transplantation for colour and viscosity is a widely used diagnostic tool to roughly assess transplant function. In analogy to urine diagnostics after kidney transplantation we analysed small peptide fragments in bile of liver transplant patients which could be indicative for the early restoration of excretory liver function after transplantation.

Bile from 8 patients was collected sequentially over 10 days after liver transplantation. Bile proteins were then separated by high percentage SDS-page gel electrophoresis. After densitometric quantification bands of interest were excised, digested with trypsin and subjected to MALDI-TOF and LC-MS-analysis.

The low molecular weight fraction of peptides below 10Kd displayed a significant 2.5 fold increase in bile during the early time course after liver transplantation (p<0,05). As a major constituent of this protein fraction a beta chain fragment of hemoglobin was identified. The appearance of this fragment paralleled the restoration of metabolic liver function after transplantation.

We hypothesise that the described hemoglobin beta chain fragment in bile is an excreted degradation product of hemoglobin which is indicative for the functional improvement of the liver after transplantation. Further work has to be done to elucidate the sensitivity and specificity of this finding for the detection of compromised liver graft function.

Bile liver transplantation beta-hemoglobin mass spectrometry