Evaluation of serum percent trisialotransferrin as potential predictive biomarker of hepatocellular dedifferentiation in chronic liver disease

High-resolution capillary zone electrophoresis and mass spectrometry for distinction of undersialylated and hypoglycosylated transferrin glycoforms in body fluids

High-resolution capillary zone electrophoresis is used to distinguish transferrin glycoforms present in human serum, cerebrospinal fluid, and serum treated with neuraminidase and N-glycosidase F. The obtained data are compared to mass spectrometry data from the literature. The main focus is on the analysis of the various asialo-transferrin, monosialo-transferrin, and disialo-transferrin molecules found in these samples. The features of capillary zone electrophoresis and mass spectrometry are reviewed and highlighted in the context of the analysis of undersialylated and hypoglycosylated transferrin molecules. High-resolution capillary zone electrophoresis represents an effective tool to assess the diversity of transferrin patterns whereas mass spectrometry is the method of choice to elucidate structural identification about the glycoforms. Hypoglycosylated transferrin glycoforms present in sera of alcohol abusers and normal subjects are structurally identical to those in sera of patients with a congenital disorder of glycosylation type I. Asialo-transferrin, monosialo-transferrin and disialo-transferrin observed in sera of patients with a type II congenital disorder of glycosylation or a hemolytic uremic syndrome, in cerebrospinal fluid and after treatment of serum with neuraminidase are undersialylated transferrin glycoforms with two N-glycans of varying structure. Undersialylated disialo-transferrin is also observed in sera with high levels of trisialo-transferrin.

The transferrin isoforms in chronic hepatitis

BACKGROUND

The aim of this study was to evaluate the effect of chronic hepatitis on the serum profile of transferrin isoforms.

METHODS

Tested group consist of 160 patients with chronic hepatitis. The samples were analyzed by capillary electrophoresis on MINICAP electrophoretic system (Sebia, France).

RESULTS

In patients with chronic hepatitis tetrasialotransferrin level was increased (P=0.002) and pentasialotransferrin decreased (P=0.009). Moreover, statistical analysis revealed that trisialotransferrin level was different according to the grade of portal/periportal activity (P=0.009), the grade of lobular activity (P=0.004) and the stage of fibrosis (P=0.022). There were no differences in tetrasialotransferrin and pentasialotransferrin according to the advancement of hepatitis activity and the stage of fibrosis (P>0.05 for all comparisons).

CONCLUSIONS

We conclude that chronic hepatitis affect the serum profile of transferrin isoforms, but only trisialotransferrin level could be useful in determining progression of chronic hepatitis and the stage of fibrosis.

Disialo-trisialo bridging of transferrin is due to increased branching and fucosylation of the carbohydrate moiety

BACKGROUND

Carbohydrate deficient transferrin (CDT) is used for detection of alcohol abuse and follow-up. High performance liquid chromatography (HPLC) of transferrin glycoforms is highly specific for identification of alcohol abuse, but unresolved disialo- and trisialotransferrin glycoforms sometimes makes interpretation difficult. The cause of this phenomenon is unknown, cannot be explained by genetic variants of transferrin, but seems to be associated with liver disease.

METHODS

Nineteen serum samples showing di-tri bridging when analyzed by HPLC were collected. Transferrin was purified by affinity chromatography, and N-linked oligosaccharides were released enzymatically. The N-glycans were further analyzed by high performance anion-exchange chromatography with pulsed amperometric detection and MALDI-TOF mass spectrometry.

RESULTS

The HPLC-analysis showed three different types of glycoform patterns. The N-glycans from fifteen samples showed patterns with increased number of triantennary structures containing one or two fucose residues. One sample contained an increased amount of triantennary glycans without fucose. Three samples showed a glycosylation pattern similar to normal transferrin.

CONCLUSIONS

The di-tri bridging phenomenon was associated with alterations in transferrin glycosylation in the majority of cases. Transferrin contained a higher extent of triantennary and often fucosylated N-linked oligosaccharides. These results may be important in future diagnostic approaches to liver diseases.