Effects of bifidobacterium on mRNA expression of tumor necrosis factor receptor-associated factor 6, glycogen synthase kinase-3β and miRNA-146a in intestinal epithelial cells induced by lipopolysaccharide in rats / 中华实用儿科临床杂志

ABSTRACT

Objective To detect the effects of bifidobacterium or bifidobacterium cultured supernatant on the mRNA expression of tumor necrosis factor receptor-associated factor 6 (TRAF6),glycogen synthase kinase-3β (GSK-3β) and the miRNA-146a in rat small intestinal epithelial cell(IEC-6) induced by lipopolysaccharide (LPS).Methods IEC-6 in logarithmic phase were randomly divided into LPS group,cultured supernatant group and inactivated bacteria group.All the 3 groups were exposed to 5 mg/L LPS for 5 hours,and then 1 mL sterile saline was added in LPS group and culturing continued for 24 hours ; 1 mL bifidobacterium cultured supernatant was added in cultured supernatant group and culturing continued for 24 hours;1 mL inactivated bifidobacterium 1 x 1010 CFU/L added in inactivated bacteria group and continued culturing for 24 hours.The mRNA expressions of TRAF6,GSK-3 β and miRNA-146a were detected by reverse transcription-polymerase chain reaction (RT-PCR).Results The level of TRAF6,GSK-3 β of culture supematant group (0.72 ± 0.05,0.46 ± 0.14) were all lower than LPS group (1.01 ± 0.14,1.02 ± 0.25),but the level of miRNA-146a(3.05 ± 0.40) was higher than that in LPS group(1.01 ± 0.12),and there were significant differences between them (t =5.278,6.316,13.218,P =0.000).The level of GSK-3 β of inactivated bacteria group(0.59 ±0.13) was significantly lower than that in LPS group(t =4.837,P =0.000).The levels of TRAF6 and miRNA-146a of inactivated bacteria group(1.05 ±0.11,0.78 ±0.22) had no significant differences with LPS group (t =0.732,1.463,P ＞ 0.05).The level of TRAF6 of cultured supernatant group was lower than that in inactivated bacteria group,and the level of miRNA-146a was higher than that in inactivated bacteria group,and there were significant differences between 2 groups (t =6.009,14.687,P =0.000).Conclusions Bifidobacterium cultured supernatant and inactivated bacteria both have certain protective effect on the IEC-6 induced by LPS.One of the protective mechanisms of bifidobacterium cultured supernatant may be achieved by elevating the expression of miRNA-146a,and decreasing the levels of inflammation related factor TRAF6 and damage related factor GSK-3β.The protective effects of inactivated bifidobacterium may be achieved by decreasing the level of damage related factor GSK-3β.