Changes Of IgG N-glycosylation In Different Diseases

As the most common post-translational modificationin biological species,protein glycosylation is involved in almost all the physiological and biochemical activities,such as cell adhension,communication,and cell proliferation.Immunoglobulin G(IgG)plays a vital role in immunity and diagnosis,of which aberrent glycosylation significantly affects the structure and function of itself.Currently,with high-throughput matrix-assisted laser desorption ionization time-of-flight mass spectrometry(MALDI-TOF-MS)and high-sensitivity nano-liquid chromatography electrospray ionization tandem mass spectrometry(nano LC-ESI-MS/MS),IgG N-glycans was first comprehensively profiled.The self-developed tool in MATLAB solution was provided which could rapidly and automatically process the data batch.Considering the importance of IgG glycosylation in precision medicine,we exploited the strategy herein to study the IgG N-glycome in different diseases,aiming at revealing the clinical role of IgG glycosylation.Colorectal cancer(CRC)is the most common cancer in digestive tracts,while recent clinic detection or diagnosis is defective.By orthogonal techniques of MALDI-MS and LC-MS,we systematically identified the IgG N-glycome in CRC,including glycans,glycan isomers and glycopeptides.Data showed CRC progression linked to increased agalactosylation,and decreased galactosylation,sialylation and fucosylation of IgG.IgG1 sialylation and IgG2 galactosylation dominate in changes of IgG glycosylation in CRC,indicating the development of this disease was probably regulated by ADCC or CDC.Moreover,several specific IgG N-glycans,isomers and glycopeptides was the candidates for early detection of CRC,especially for isomers and glycopeptides.Multiple myeloma(MM)is the second hematologic malignant disease,while the relationship between IgG glycosylation and MM is unknown.This study exploited the IgG glycosylation to reveal the molecular mechnism in MM and medical treatment.MM strongly associates with increased IgG agalactosylation and decreased bisection,fucosylation and galactosylation.Alteration of IgG galactosylation in MM may result from IgG1 and IgG2,while bisection possibly derived from IgG1 and IgG3/4.Fucosylation of IgG2 may dominantly contributed to the changes of IgG fucosylation in MM,whereas sialylation of IgG3/4 may be subclass-specific.Comparative study suggested subclass-specific IgG glycosylation deserved higher diagnostic merit than IgG N-glycans.Therefore,we anticipated that MM progression enrolled the IgG glycosylation,especially for IgG subclass.Additionally,longitudinal study showed IgG glycosylation fluctuated during the whole phase of medication,especially for fucosylation,implicating that IgG glycosylation is important for pharmacology and drug administration.Haff disease(HD)is an unexplained syndrome occurred within 24 h by consumption of cooked fishery or crustacean's products.Herein,we analyzed the association between HD and N-glycosylation of total serum and serum IgG.Serum mannosylation,agalactosylation,and bisection were significantly decreased in HD,while digalactosylation,and sialylation were significantly increased.Besides,specific glycans can distinguish HD and controls.IgG concentration was profoundly decreased in HD,whose accuracy is up to 90%,indicating its promising criteria for HD.HD correlates with reduced sialo bisection,neutral fucosylation and di-sialylation,and elevated mono-galactosylation of IgG.Galactosylation and sialylation of IgG1 and IgG2 was subclass-specific,respectively.Similarly,bisection of IgG in HD mainly resulted from the alteration in IgG1 and IgG2.Together,HD onset is likely to be mediated by Wnt or DC-SIGN dependent signaling pathway or ADCC or CDC activity.In conclusion,this study has built a MS-based analytical procedures for clinical samples,focusing on the analysis of IgG N-glycome in three representative human diseases of different types.It is suggested that differential expression of IgG glycosylation toughly correlates with CRC,MM and HD.Additionally,different diseases show different profile of IgG N-glycosylation,while alterated glycosylation in specific disease is subclass-specific.Importantly,several specific glycans,glycan isomers or glycopeptides of IgG were promising biomarker for early detection of diseases.Therefore,revealing the changes of IgG glycosylation in diseses would help to reveal the pathogenesis and obtain the novel biomarkers,laying the foundation for clinical research,precision medicine and drug development of other diseases.