Abstract: The instant disclosure provides methods of detecting N-glycopeptides in a sample by contacting the sample with one or more exoglycosidases and detecting the N-glycopeptides by mass spectrometry. Also provided are methods of detecting the presence or progression of a liver disease and treating said liver disease.

Abstract: Provided is a sensitive and specific LC-MS-MRM quantification method that distinguishes outer-arm and core fucosylated configurations of N-glycopeptides. Advantage is taken of limited fragmentation of the glycopeptides at low collision energy (collision-induced dissociation) CID to produce linkage-specific Y-ions. These ions are selected as multiple reaction monitoring (MRM) transitions for the quantification of the outer-arm and total fucosylation of 23 glycoforms of 9 glycopeptides in 7 plasma proteins. The method permits quantification of the glycoforms directly in plasma or serum without fractionation of samples or glycopeptide enrichment. A pilot study of fucosylation in liver cirrhosis of hepatitis C vims (HCV) and non-alcoholic steatohepatitis (NASH) etiologies demonstrated that liver cirrhosis is consistently associated with increased outer-arm fucosylation of a majority of the analyzed proteins.

Abstract: Provided are in vitro serologic methods of assessing the presence of, and assessing the progression of, liver fibrosis in a subject. Also provided are methods of assessing efficacy of an agent for the treatment of liver fibrosis, and methods of treating liver fibrosis. The methods involve quantitatively measuring di-sialylated and mono-sialylated O-glycoforms of a peptide fragment of hemopexin (HPX) in a test serum sample obtained from a test subject, and comparing the measured amounts of di-sialylated and mono-sialylated O-glycoforms of the peptide fragment of hemopexin to a reference amount. In certain embodiments, the measuring is performed using LC-MS/MS-MRM (liquid chromatography/tandem mass spectrometry/multiple reaction monitoring). In certain embodiments, the measuring is performed using LC/MS3 (liquid chromatography with triple-stage mass spectrometric detection).

Abstract: Provided are in vitro serologic methods of assessing the presence of, and assessing the progression of, liver fibrosis in a subject. Also provided are methods of assessing efficacy of an agent for the treatment of liver fibrosis, and methods of treating liver fibrosis. The methods involve quantitatively measuring di-sialylated and mono-sialylated O-glycoforms of a peptide fragment of hemopexin (HPX) in a test serum sample obtained from a test subject, and comparing the measured amounts of di-sialylated and mono-sialylated O-glycoforms of the peptide fragment of hemopexin to a reference amount. In certain embodiments, the measuring is performed using LC-MS/MS-MRM (liquid chromatography/tandem mass spectrometry/multiple reaction monitoring). In certain embodiments, the measuring is performed using LC/MS3 (liquid chromatography with triple-stage mass spectrometric detection).