Bacillus amyloliquefaciens SC06 inhibits ETEC-induced pro-inflammatory responses by suppression of MAPK signaling pathways in IPEC-1 cells and diarrhea in weaned piglets

Enterotoxigenic Escherichia coli (ETEC) are the main pathogens which cause pro-inflammatory responses in intestinal epithelial cells and subsequent diarrhea in pigs, leading to a reduced growth rate and increased mortality. Administration of probiotics as feed additives displayed health benefits against intestinal infections. Bacillus amyloliquefaciens SC06 (Ba) is a candidate probiotic isolated from soil and kept at China Center for Type Culture Collection. In this study, we investigated the effect of Ba on the pro-inflammatory responses induced by ETEC in IPEC-1 cells and on diarrhea in the weaned piglets. The results in vitro showed that the mRNA expression of IL-6, IL-8, TNF-α, and IL-1α in IPEC-1 cells co-cultured with ETEC was significantly increased compared to the control, however, the gene expression of these genes decreased when IPEC-1 cells were incubated 24 h with Ba prior to ETEC infection. Furthermore, the ETEC-mediated activation of ERK1/2, p38 and JNK in IPEC-1 cells was attenuated after Ba treatment. The results in vivo showed that the dietary supplementation with Ba increased daily body weight gain by 11.85% (P<0.05) and decreased the diarrhea incidence by 79.17% compared with the control group (P<0.01), respectively. Together, our data suggest that Ba treatment may inhibit ETEC-induced pro-inflammatory responses by suppression of MAPK signaling pathways in intestinal epithelial cells, which provides a rationale for decreased diarrhea incidence in the Ba-supplemented diet of the weaned piglets.