Deciphering N-Glycosylation Dynamics of Serum Monoclonal Immunoglobulins in Multiple Myeloma via EThcD-sceHCD-MS/MS
Huixian Li, Wanhong Lu, Qian Jin, Jiping Sun, Li Gao, Juanjuan Hu, Yingying Ling, Wenyu Zhao, Yong Zhang, Xinfang Xie
Abstract
Serum glycoprotein glycosylation changes can indicate disease onset and progression. However, the site-specific N-glycosylation of monoclonal immunoglobulins (M-proteins) in multiple myeloma (MM) and its clinical implications are unclear. In this study, we isolated pathogenic micromonoclonal IgA or IgG (approximately 2 μg) from IgA-MM patients ( n = 22) and IgG-MM patients ( n = 30), and normal polyclonal IgA and IgG from healthy controls (HCs) ( n = 16). Using EThcD-sceHCD-MS/MS, the N-glycosylation dynamics of serum M-proteins in MM were determined. Compared with polyclonal IgA1 from HCs, monoclonal IgA1 from IgA-MM patients had higher fucosylation (58.1% vs 32.1%, p < 0.001), sialylation (68.0% vs 50.8%, p = 0.011), and mannosylation (1.5% vs 0.3%, p < 0.001). While, monoclonal IgG1 from IgG-MM patients had higher fucosylation (97.8% vs 95.3%, p < 0.001). In addition, specific N-glycan abundances correlated with MM clinical features: for IgA1, HexNAc5Hex5Fuc1NeuAc1 was associated with hypocomplementemia; for IgG1, HexNAc4Hex3Fuc1 was associated with the serum albumin level ( r = −0.363, p = 0.049) and estimated glomerular filtration rate ( r = −0.433, p = 0.017); and HexNAc4Hex5 was associated with therapeutic prognosis. In conclusion, monoclonal IgA1 and IgG1 in MM patients and their polyclonal isotypes in HCs have distinct N-glycosylation profiles, and specific N-glycans of M-proteins are associated with MM characteristics and therapeutic prognosis.