High-Throughput Quantitative Profiling of Serum N-Glycome by MALDI-TOF Mass Spectrometry and N-Glycomic Fingerprint of Liver Fibrosis

• Published in: Clinical chemistry (Baltimore, Md.) Vol. 53; no. 7; pp. 1254 - 1263
• Main Authors: Kam, Richard K.T, Poon, Terence C.W, Chan, Henry L.Y, Wong, Nathalie, Hui, Alex Y, Sung, Joseph J.Y
• Format: Journal Article
• Language: English
• Published: Washington, DC Am Assoc Clin Chem 01.07.2007; American Association for Clinical Chemistry; Oxford University Press
• Subjects: Analytical, structural and metabolic biochemistry; Biological and medical sciences; Biomarkers - blood; Biopsy; Congenital diseases; Disease; Feasibility Studies; Female; Fundamental and applied biological sciences. Psychology; Glycosylation; Hepatitis C, Chronic - complications; Humans; Infectious diseases; Investigative techniques, diagnostic techniques (general aspects); Linear Models; Liver; Liver cirrhosis; Liver Cirrhosis - blood; Liver Cirrhosis - diagnosis; Liver Cirrhosis - etiology; Liver diseases; Male; Mass spectrometry; Medical sciences; Middle Aged; Ovarian cancer; Polysaccharides - blood; Protein Array Analysis - methods; Proteins; Regression analysis; Reproducibility of Results; Sensitivity and Specificity; Serum; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Spectrum analysis; Hepatic fibrosis; Rapid technique; Fingerprint method; Clinical biology; Digestive diseases; Hepatic disease; Serum; Biochemistry; Molecular biology; Mass spectrometry; Quantitative analysis
• DOI: 10.1373/clinchem.2007.085563
• ISSN: 0009-9147

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. 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. 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. 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.