Protective Effect Of Lycium Barbarum Polysaccharide On Sepsis-induced Intestinal Epithelial Barrier Injury

ObjectiveThe beneficial effects of Lycium barbarum polysaccharide（LBP）was explored on the model of Caco-2 intestinal epithelial cell and further verified in the sepsis-induced intestinal epithelial barrier damage in mice.The intention is to offer some theoretical basis for the treatment of sepsis-induced intestinal mucosal barrier injury in clinical practice from a new perspective.Methods1.Safe drug concentration of LBP in Caco-2 intestinal epithelial cells was measured using MTT assay.2.The inflammatory injury model of Caco-2 intestinal epithelial cells was established by lipopolysaccharide.The effects of LBP on Caco-2 cell activity,pro-inflammatory cytokine（TNF-α,IL-6,IL-1β）levels in cell culture media,altered intestinal epithelial barrier permeability,apoptosis-related proteins,and tight junction proteins were observed.3.The expression levels of TLR4,NF-κB and other key proteins in Caco-2 cells were detected,and the possible mechanism of LBP was preliminarily explored.4.The safety of LBP in BALB/C mice was verified.Experimental animals were pretreated with normal saline or different doses of LBP using gavage.Cecum ligation and puncture（CLP）was used to establish sepsis mouse model.Survival analysis was performed and clinical activity scores were recorded.5.According to the results of survival analysis,experimental mice were divided into 5 groups,namely Control group,CLP model group,low dose group（200 mg/kg）,medium dose group（400 mg/kg）,and high dose group（800 mg/kg）.After pretreatment with or without LBP,CLP established a sepsis mouse model and recorded the histological score of intestinal mucosal injury of experimental mice with LBP to verify the protective effect of LBP on septic mice.6.The local anti-inflammatory activity of LBP in septic mice was verified by detecting the expression levels of pro-inflammatory cytokines in mice ileal tissues.7.The effect of LBP on intestinal mucosal barrier permeability in sepsis mice was investigated.The expression levels of tight junction protein and apoptosis-related proteins in Intestinal tissue of experimental mice were detected.The protective effect of LBP on intestinal mucosal barrier in experimental mice was verified.Results1.LBP was a safe dose at 0 μg/ml-400 μg/ml and had no effect on the cell activity of Caco-2 cells.2.After LBP pretreatment,the levels of pro-inflammatory cytokines in the supernatant of lipopolysaccharide induced inflammatory cells were inhibited,the permeability of intestinal epithelial cell barrier was decreased,the expression of intestinal tight junction protein was increased,apoptosis was inhibited,and the expression of TLR4,NF-κB and other proteins were down-regulated.3.Acute toxicity assays found that LBP did not cause death,elevated levels of pro-inflammatory cytokines,or histological damage to vital organs in the experimental mice.4.The survival time and clinical activity score of sepsis mice were improved,the histopathological injury of intestinal tissue was reduced,the level of pro-inflammatory cytokines in ileum was reduced,and the injury of intestinal mucosal barrier was improved after LBP pretreatment.In addition,we observed that the activation of TLR4/NF-κB signaling pathway was inhibited by LBP.Conclusion1.The damage of lipopolysaccharide to Caco-2 intestinal epithelial cell barrier could be reduced by LBP.2.LBP has a protective effect on septic mice and sepsis-induced intestinal mucosal barrier damage.3.The protective effect of LBP may be related to inhibiting the activation of TLR4/NF-κB signaling pathway.