Protective effect of Bombyx mori gloverin on intestinal epithelial cells exposure to enterotoxigenic E. coli

Bombyx mori gloverin A2 (BMGlvA2) is an induced antimicrobial insect protein isolated from Bombyx mori. This study was conducted to explore the effect and potential mechanisms of BMGlvA2 on inflammatory responses and cellular functions in intestinal epithelial cells (IPEC-J2) exposure to enterotoxigenic E. coli (ETEC). IPEC-J2 cells pretreated with or without BMGlvA2 (12.5 μg/mL) were challenged by ETEC K88 (1×10⁶ CFU/well) or culture medium. We show that BMGlvA2 pretreatment increased the cell viability and improved the distribution and abundance of tight junction protein ZO-1 in IPEC-J2 cells exposure to ETEC (P < 0.05). Interestingly, BMGlvA2 not only decreased the expression levels of inflammatory cytokines such as the tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β), but also decreased the expression level of Caspase3 and the apoptosis rate in the ETEC-challenged cells (P < 0.05). Importantly, BMGlvA2 decreased the protein abundances of two critical inflammation-associated signaling proteins, phosphorylated nuclear factor-kappa-B inhibitor alpha (p-IκBα) and phosphorylated nuclear factor-kappa B (p-NF-κB), in the ETEC-challenged cells. These results indicate that BMGlvA2 attenuates ETEC-induced inflammation in the IPEC-J2 cells by regulating the NF-κB signaling pathway, resulting in decreased secretion of inflammatory cytokine and reduced cell apoptosis.