The Effects Of Fungal Cell Wall β-Glucan On Intestinal Mucosal Immune In Ulcerative Colitis

Dysbiosis of the gut microbiota are implicated in the pathogenesis of ulcerative colitis.Gut contained fungal community may participate in the development of ulcerative colitis.Intestinal epithelial cells play an important role in maintaining the intestinal homeostasis.While there is no study about the relationship between fungi and IECs in UC at present.Part Ⅰ The fungal cell walls β-glucan effects on intestinal inflammation in miceAims: To investigate the effects of the component of fungal cell walls β-glucan on intestinal inflammation in mice,the expression of inflammatory cytokines and the regulation mechanisms.Methods: dn TGFβRII mice and wild type mice were gavaged once with curdlan weekly.The pathologic features were assessed by H&E staining.The expression of inflammatory cytokines and the activation of signaling pathway were detected by Western blot.Results: 1.dn TGFβRII mice experienced increased weight loss(*P<0.05,**P<0.01),wild type mice experienced growth slowly.2.The histology score was higher in the dn TGFβRII mice gavaged with curdlan(*P<0.05),no significant differences in wild type mice;3.The expression of IL-23 increased in dn TGFβRII mice gavaged with curdlan(**P<0.01).Conclusion: The fungal cell walls component β-glucan aggravated colitis and the expression of inflammatory cytokines in dn TGFβRII mice,no significant differences in wild type mice,which suggested that fungi may involved in the pathogensis of IBD.Part Ⅱ β-glucan induced intestinal inflammation through Ctype lectin receptor Dectin-1Aims: To investigate the effects of β-glucan on intestinal epithelial cell and the regulation mechanism of receptor Dectin-1.Methods: Human intestinal epithelial cell lines Caco-2 and HT-29 cells stimulated with β-glucan particles zymosan.The expression of inflammation cytokines IL-23p19 and activation of NF-κB pathway were measured by Western blot.After Caco-2 and HT-29 cell line pre-cultured with or without inhibitor Laminarin and IMD0354,the expression of inflammatory cytokines IL-23p19 and activation of NF-κB pathway were estimated by western blot.Results: 1.Zymosan induces intestinal epithelial cell inflammation through the Dectin-1 recognition 2.NF-κBp65 was activated inintestinal epithelial cell after the phosphorylation of IκB after zymosan treatment.Conclusion: Zymosan induced the inflammatory response in intestinal epithelial through the Dectin-1 recognition,suggested that zymosan maybe related to the injury of intestinal epithelial barrier in UC.Part Ⅲ Dectin-1 involved in intestinal epithelial inflammation and regulate the signaling pathwayAim:To investigate the expression levels of Dectin-1 and IL-23 in UC patients’ colonic tissue and its regulation of NF-κB pathway.Methods: The expression levels of Dectin-1 and IL-23 in UC patients’ colonic were detected by immunohistochemistry,real-time PCR and western blot.The activation of NF-κB pathway was evaluated in UC patients by western blot.Results: 1.Opportunistic pathogen fungus level were higher in IBD patients’ fecal sample.2.The expression of Dectin-1 and IL-23 was increased in UC patients’ colonic tissue(**P<0.01).3.Phosphorylation of IκB and the activation of NF-κBp65 were enhanced in UC patients’ colonic tissue.Conclusion: Dectin-1 and IL-23 expression in the colonic tissues of UC patients were significantly increased,phosphorylation of IκB and the activation of NF-κBp65 were enhanced,which indicate Dectin-1 maybe involved in the occurrence of intestinal inflammation in UC.