流感与COVID-19患者的免疫球蛋白G糖基化差异

Differences in Immunoglobulin G Glycosylation Between Influenza and COVID-19 Patients

The essential role of immunoglobulin G(IgG)in immune system regulation and combatting infectious diseases cannot be fully recognized without an understanding of the changes in its N-glycans attached to the asparagine 297 of the fragment crystallizable(Fc)domain that occur under such circumstances.These glycans impact the antibody stability,half-life,secretion,immunogenicity,and effector functions.Therefore,in this study,we analyzed and compared the total IgG glycome—at the level of individual glycan structures and derived glycosylation traits(sialylation,galactosylation,fucosylation,and bisecting Nacetylglucosamine(GlcNAc))—of 64 patients with influenza,77 patients with coronavirus disease 2019(COVID-19),and 56 healthy controls.Our study revealed a significant decrease in IgG galactosylation,sialylation,and bisecting GlcNAc(where the latter shows the most significant decrease)in deceased COVID19 patients,whereas IgG fucosylation was increased.On the other hand,IgG galactosylation remained stable in influenza patients and COVID-19 survivors.IgG glycosylation in influenza patients was more time-dependent:In the first seven days of the disease,sialylation increased and fucosylation and bisecting GlcNAc decreased;in the next 21 days,sialylation decreased and fucosylation increased(while bisecting GlcNAc remained stable).The similarity of IgG glycosylation changes in COVID-19 survivors and influenza patients may be the consequence of an adequate immune response to enveloped viruses,while the observed changes in deceased COVID-19 patients may indicate its deviation.