The Mechanism Of Intestinal Epithelial Cells Core Fucosylation Protecting Against Salmonella Typhi Infection Via Regulating The Abundance Of Intestinal Microbiota

Background:The fucosylation of intestinal epithelial cells?IECs?is closely related to the prevention against pathogen infection,and the development of colitis and colon cancer.Recently studies have indicated that the interaction between commensals and IECs and the immune function of intestinal mucosa are mediated by epithelial?1,2 fucosylation.Moreover,highly core fucosylated maternal milk can facilitate the growth of Lactobacillus and Bifidobacterium in gut of infants,and evoke B Cell activation of neonates.These indicates that glycosylation of IECs may contribute to the resistance to pathogen in intestine and has a major impact on the remodeling of the commensal bacterial.The core fucosylation catalyzed by fucosyltransferase 8?Fut8?is the major fucosylation pattern on the on IECs.Wnt signaling pathway was found contributes to the rapid elevation of core fucosylation in breast cancer cells by enhancing Fut8transcription,and can be activated by the combination of Salmonella and IECs.However,no study has investigated the interaction between IECs core fucosylation and gut microbiota,and whether this interaction affects immune responses during infection.In this study,we found that S.Typhi up-regulated the expression of core fucosylation via the activation of Wnt signaling pathway.Moreover,Core fucosylation of IECs protects against S.Typhi infection via up-regulating the biological antagonism of intestinal microbiota.Objective:To investigate the interaction between intestinal epithelial cells?IECs?core fucosylation and gut microbiota,and the role of this interaction in protecting S.Typhi infection,we infect the Fut8^+/+and Fut8^+/-mice and Caco-2 cells and performed the following experiments.Methods:?1?Fut8^+/+and Fut8^+/-mice were infected with Salmonella enterica subsp.enterica serovar Typhi?S.Typhi?.?2?Comparing the resistence against S.Typhi of Fut8^+/+and Fut8^+/-mice,by daily weighing and HE staining of intestine and colon.?3?The level of core fucosylation before and after Fut8^+/+and Fut8^+/-infected of was detected by Lectin Blot?LB?.?4?The gut microbiota of Fut8^+/+and Fut8^+/-mice and the difference before and after S.Typhi infection was assessed by 16S r RNA sequencing.?5?The changing of Wnt signaling pathway protein expression of intestinal mucosa was detected by Western blot and Immunofluorescence.?6?In vitro,the effects of S.Typhi infection on core fucosylation of Caco-2 cells,and the underlying mechanism of were further determined.The Wnt signaling antagonist,Dickkopf-1?Dkk-1?,was used to confirm whether IEC core fucosylation was mediated by Wnt singaling pathway.?7?The Ch IP was used to further validate whether Fut8 is the downstream target of T cell factor?TCF?in the Wnt signaling pathway.Results:?1?The core fucosylation is ubiquitous expressed in the intestine and affects gut microbiota.?2?The abundance of Lactobacillus is decreased in Fut8^+/-mice compared with Fut8^+/+mice.?3?Fut8^+/-mice is more susceptive to S.Typhi infection compared with Fut8^+/+mice.?4?S.Typhi infection upregulated the core fucosylation level of IECs and induced changing of gut microbiota in mice,characterized by the increase of Lactobacillus and Akkermansia.?5?S.Typhi infection activated the expression of Wnt signaling pathway molecules and increased the expression of core fucosylation.?6?S.Typhi induced the activation of Wnt signaling pathway,leads to the accumulation of?-catenin,and enhances TCF binding to Fut8 promoter regions,contributes to the rapid elevation of IECs core fucosylation.Conclusion:Core fucosylation of IECs protects against S.Typhi infection via up-regulating the biological antagonism of intestinal microbiota.Moreover,S.Typhi up-regulated the expression of core fucosylation mainly by enhancing the transcriptional activity of Fut8via the activation of Wnt signaling pathway enhancing TCF binding to its promoter regions.