High-throughput quantitative profiling of serum N-glycome by MALDI-TOF mass spectrometry and N-glycomic fingerprint of liver fibrosis.
BACKGROUND
The use of MALDI-TOF mass spectrometry (MS) in quantitative glycan profiling has not been reported. In this study, we attempted to establish a high-throughput quantitative assay for profiling serum N-glycome, and we applied the new assay to identifying serum N-glycans for diagnosis of liver fibrosis and cirrhosis.


METHODS
N-glycans from whole serum proteins in 2 microL serum were released by enzymatic digestion, cleaned up by hydrophilic chromatography, and subsequently quantitatively profiled with a linear MALDI-TOF MS system, which was originally designed for quantitative proteomic profiling. Serum N-glycome profiles from 46 patients with chronic hepatitis B infection and with different degrees of liver fibrosis were examined.


RESULTS
The intra- and interassay CVs of peak intensities of the standard N-glycans were <8% and <17%, respectively. When the assay was applied to the analysis of serum N-glycome profiles, 17 peaks were found to be potential biomarkers for detection of liver fibrosis/cirrhosis. Linear regression analysis revealed that 4 peaks of 1341.5, 1829.7, 1933.3, and 2130.3 m/z (all P <0.005) had complementary value in detecting liver fibrosis and included them, but not any serological markers, in the diagnostic model. Leave-one-out cross-validation showed the diagnostic model could identify significant fibrosis (Ishak score > or = 3) and cirrhosis (Ishak score > or = 5), both at 85% accuracy.


CONCLUSIONS
This is the first study to illustrate the quantitative aspect of MALDI-TOF MS in N-glycome profiling and the first study to reveal the potential value of the serum N-glycan profile for identifying liver fibrosis.
Kam
Richard K T
RK
Li Ka Shing Institute of Health Sciences, Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong SAR.
Poon
Terence C W
TC
Chan
Henry L Y
HL
Wong
Nathalie
N
Hui
Alex Y
AY
Sung
Joseph J Y
JJ
D015415:Biomarkers / Q000097:blood; D005240:Feasibility Studies; D005260:Female; D019698:Hepatitis C, Chronic / Q000150:complications; D006801:Humans; D016014:Linear Models; D008103:Liver Cirrhosis / Q000097:blood* / Q000175:diagnosis / Q000209:etiology; D008297:Male; D008875:Middle Aged; D011134:Polysaccharides / Q000097:blood*; D040081:Protein Array Analysis / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D044967:Serum; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D015415:Biomarkers; D011134:Polysaccharides