Study On The Interaction Between Intestinal Macrophages And Lgr5~+ Stem Cells In Radiation Injury

Objective:To explore the interaction between intestinal lamina propria macrophages and Lgr5~+stem cells during radioactive intestinal injury,and to provide experimental evidence for the treatment of intestinal injury patients after radiotherapy.Methods:1.Immunohistochemical staining was used to detect the expression of intestinal macrophages before and after irradiation in mice.2.The expression of MIF,M-CSF,IL1ra and IGF1 in serum was detected by ELISA.3.Mouse Lgr5~+stem cells and intestinal lamina propria macrophages were isolated by magnetic beads sorting.4.Western blot was used to detect the expression of lysozyme and CD68.5.The expression of cytokines in supernatant of Lgr5~+stem cells and intestinal lamina propria macrophages was detected by Proteome Profiler technique.6.The expression of GFP and MIF,CD68 and EGFR were detected by double immunofluorescence assay.7.The expression of GFP and Reg3g and EGF in tissues were detected by double staining immunohistochemistry.Results:1.The percentage of lamina propria macrophages in the bottom of the intestinal crypts was the highest at 6 h after irradiation at 15 Gy.2.The expression of MIF and IGF1 in the serum was decreased and the expression of M-CSF and IL1ra increased after irradiation in mice.3.Magnetic beads sorted by the Lgr5~+stem cells do not express lysozyme,macrophages do have CD68 expression.4.The expression of EGF and Reg3g in Lgr5~+stem cells and tissues cultured in vitro were increased after irradiation.5.The expression of Angiopoietin-1 and Dll-1 was decreased and the expression of MMP-2 was not changed and the expression of CCL6 was increased in the lamina propria macrophages of the intestine after irradiation.6.EGFR expression in macrophages in mouse tissues.Conclusion:1.The radiation-induced intestinal injury model was established in 6 h after mouse 15 Gy irradiation.2.The expression of MIF in Lgr5~+stem cells decreased and the migration ability of intestinal macrophages increased.3.After the irradiation,Reg3g was highly expressed in Lgr5~+stem cells,and the feedback effect was indirectly regulated by caspase1,which inhibited the apoptosis of Lgr5~+stem cells and promoted its growth.In addition,Reg3g may recruit macrophage.4.After irradiation,Lgr5~+stem cells overexpress EGF,recruited more intestinal macrophages migrate,and combined with macrophage expression of EGFR,start EGF-EGFR signal.5.Intestinal macrophages produce Dll-1,activate Notch signaling pathway,regulate the proliferation and differentiation of Lgr5~+stem cells,this pathway in this experimental radiation lead to intestinal injury model to promote intestinal epithelial repair may not play a dominant role.