Core Fucose Of Maternal Milk N-glycan Regulate Gut Lactobacillus Spp. And The Following Activation Of B Cells In Infants

The human milk glycobiome plays a pivotal role in shaping the gut microbiota of infants.In addition to providing nutrients and energy for newborns,glycans in human milk inhibit the adhesion of pathogens,and promote intestinal colonization and growth of probiotics,resulting in a Bifidobacterium and Lactobacillus enriched gut micro-ecosystem in breast-fed infants.This early-life microbiome contributes significantly to the health outcomes of infants by regulating the development of their immune system.High fucosylation is a general feature of human milk glycoproteins,and the N-glycans of milk proteins are heavily core-fucosylated by fucosyltransferase 8（Fut8）.Fut8-mediated core fucosylation is an important post-translational process in mammals.Indeed,the most important and abundant milk proteins including lactoferrin（LF）and immunoglobulins（IgG,IgM,sIgA）are heavily core-fucosylated.Few studies have focused on the regulatory role of milk protein glycosylation on the gut microbiota of neonates.In this study,we suggest that core fucose of maternal milk N-glycan promotes the dominant growth of gut Lactobacillus spp.Bifidobacterium spp.and the following activation of B cells in infants.Objective:To find the correlation between the maternal milk protein core-fucosylation levels of Chinese mothers and the gut microbial patterns of their breast-fed infants during early lactation.Methods:（1）Maternal milk protein core-fucosylation levels of Chinese mothers was evaluated by Lectin Blot（LB）.（2）The gut microbial patterns of breast-fed infants during early lactation was evaluated by 16S rRNA gene sequencing and metagenomic sequencing.（3）we compared the gut microbiota of Fut8^+/+off-springs that fed by Fut8^+/-and Fut8^+/+maternal mice by 16S rRNA gene sequencing.（4）we compared the immune development of Fut8^+/+off-springs that fed by Fut8^+/-and Fut8^+/+maternal mice by flow cytometry（FACS）.（5）using 3-83 B cell line,we further studied the regulatory mechanism of milk protein core fucosylation on B cell proliferation and activation via Westem Blot（WB）to detect B cell receptor（BCR）protein phosphorylation.Results:（1）Core fucosylated N-glycans in human milk can selectively promote the colonization of specific microbial groups,such as Bifidobacterium and Lactobacillus in infants.（2）The Fut8^+/+offspring fed by Fut8^+/-mice have a distinct gut microbial profile and a lower proportion of B lymphocytes in spleen.（3）Core fucosylated oligosaccharides promote the growth of Lactobacillus spp.（4）In vitro studies demonstrated that the L-fucose metabolites are responsible for the activation of B cells and through Syk-mediated signaling pathway.Conclusion:This study demonstrates that the core fucosylation of maternal milk N-glycan evokes neonatal B cell development by selectively promoting the L-fucose metabolism of gut Lactobacillus spp.This provides novel evidence for the critical role of milk protein glycosylation in shaping early-life gut microbiota and promoting the immune development of infants.The special core fucosylated oligosaccharides might be promising prebiotics for the personalized nutrition of infants.