Effect of Bifidobacterium on the mRNA expression levels of TRAF6, GSK-3β, and microRNA-146a in LPS-stimulated rat intestinal epithelial cells.

We investigated the effect of inactivated Bifidobacterium on the mRNA expression of TRAF6, GSK-3β, and microRNA-146a in lipopolysaccharide (LPS)-stimulated rat small intestinal epithelial cells (IEC-6s). IEC-6s were randomly divided into an LPS group, a culture supernatant group, and an inactivated bacteria group. After stimulation with LPS for 5 h, the three groups were treated as follows: the LPS group was cultured for 24 h with sterile saline; the culture supernatant group was cultured with Bifidobacterium (infantis strain) culture supernatant for 24 h; and the inactivated bacteria group was cultured with inactivated infantis Bifidobacterium for 24 h. Reverse transcription polymerase chain reaction was used to determine mRNA expression levels. The mRNA expression levels of TRAF-6 and GSK-3β in the culture supernatant group were lower, and microRNA-146a expression was higher, compared with the LPS group (t = 5.278, P = 0.000; t = 6.316, P = 0.000; t = 13.218, P = 0.000, respectively). GSK-3β mRNA expression in the inactivated bacteria group was lower than in the LPS group (t = 4.837, P = 0.000). There was no difference in the mRNA expression levels of TRAF-6 and microRNA-146a between the two groups (t = 0.732, P = 0.472 and t = 1.463, P = 0.164). Both the culture supernatant and the inactivated Bifidobacterium had a protective effect on LPS-stimulated IEC-6s. The protective effect of Bifidobacterium may be achieved through increased microRNA-146a by reducing levels of TRAF6 and GSK-3β; the protective effect of inactivated Bifidobacterium may be achieved by reducing levels of GSK-3β.