Total plasma N-glycome changes during pregnancy

During pregnancy, the mother faces a major immunological challenge. Most of the major plasma proteins have important immunological functions, and altered levels of these major proteins have been reported during pregnancy, potentially providing immunosuppression. A large number of the high abundance plasma proteins are post-translationally modified by N-glycans, and while it is now understood that these glycans may also affect the immunological functions, their pattern has not been studied in relation to pregnancy. Here, the N-glycosylation profile of 32 pregnant women was determined over the course of their pregnancy using a multiplexed CGE-LIF method. Moreover, for 6 women, the glycosylation profiles of the proteins IgG, IgA, and alpha1-antitrypsin were monitored. For total plasma, 16 glycan signals showed differential expression during pregnancy. In general the levels of largely sialylated bi-, tri-, and tetra-antennary glycans were increased during pregnancy, while biantennary glycans with no more than one sialic acid were decreased. Similarly altered glycosylation profiles were observed for the individual proteins IgG, with a decrease of digalactosylated biantennary glycans after delivery, and alpha1-antitrypsin, on which increased levels of triantennary glycans were observed during pregnancy. Overall, these results show altered glycosylation profiles both for total plasma glycoproteins and on individual proteins during pregnancy, which may contribute to immunosuppression and have other biological functions.