Impact and mechanisms of ganoderma lucidum polysaccharide on ETEC-induced enteritis
Objective To study on the effects and mechanisms of ganoderma lucidum polysaccharides(GLP)on enteritis induced by enterotoxigenic Escherichia coli(ETEC)in mice.Methods Twenty-four 6-to 8-weeks-old male SPF Kunming mice were selected.A mouse enteritis model was induced by intraperitoneal injection of ETEC bacterial suspension.Mice were divided into normal group,ETEC infection group,ETEC infection+high-dose GLP group,and ETEC infection+ow-dose GLP group using a random number table method,six mice in each group.Pathological changes in mice small intestine tissue were observed through HE staining.The expression of C-reactive protein(CRP),tumor necrosis factor-(TNF)-α,and interleukin(IL)-6 proteins in mice small intestine tissues were detected by Western blot method,and expression levels of Toll-like receptor 4(TLR4),nuclear factor-KB(NF-κB)p65,and myeloid differentiation factor 88(MyD88)mRNA in mice small intestine tissues were detected by RT-qPCR technique to explore the regulatory effect of GLP on ETEC-induced mice intestinal inflammation through TLR4/NF-κB signaling pathway.Results Compared with control group,mice infected with ETEC showed lethargy,reduced appetite,damaged intestinal villi,significant inflammatory infiltration in tissues,and an increasing trend in disease activity index(DAI)scores(P＜0.05).The relative expression levels of TLR4,NF-κB p65,and MyD88 mRNA,as well as protein expression levels of CRP,TNF-α,and IL-6 in small intestine tissues of mice,were significantly increased(P＜0.01).Compared with ETEC-infected group,mice in different dosage groups showed improvements in mental status and appetite.The relative expression levels of TLR4,NF-κB p65,and MyD88 mRNA in small intestine tissues of mice were significantly decreased in all dosage groups(P＜0.01).In ETEC infection+high-dose group,protein expression levels of CRP,TNF-α,and IL-6 in small intestine tissues of mice were significantly decreased(P＜0.01),while the decrease in ETEC infection+low-dose group was not significant(P＞0.05).Compared with ETEC infection+low-dose group,ETEC infection+high-dose group showed significant decreases in relative expression levels of TLR4 and MyD88 mRNA,as well as in protein expression level of IL-6 in small intestine tissues of mice(P＜0.01 or P＜0.05).Conclusion GLP can effectively relieve intestinal inflammation induced by ETEC,and may exert its anti-inflammatory effect through regulating TLR4/NF-κB signaling pathway,which may be proportional to its concentration.
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