Immunomodulation and signaling mechanism of Lactobacillus rhamnosus GG and its components on porcine intestinal epithelial cells stimulated by lipopolysaccharide.

Abstract

This study aimed to evaluate the immunomodulatory effects and signaling mechanisms of Lactobacillus rhamnosus GG (LGG) and its components [surface-layer protein (SLP), DNA, exopolysaccharides, and CpG oligodeoxynucleotides] on lipopolysaccharide (LPS)-stimulated porcine intestinal epithelial cell (IEC) IPEC-J2. The mRNA expressions of inflammatory cytokines and Toll-like receptors (TLRs) were measured by quantitative real-time polymerase chain reaction. Activation of mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-κB) signaling was detected by western blot and immunofluorescence. Pretreatment of IPEC-J2 cells with LGG, SLP, or exopolysaccharides significantly alleviated LPS-induced inflammatory cytokines and TLR activation at mRNA level. LGG, SLP, and exopolysaccharides also attenuated LPS-induced MAPK and NF-κB signaling activations. CpG oligodeoxynucleotides significantly increased the interleukin 12, tumor necrosis factor α, and TLR9 mRNA levels and enhanced NF-κB signaling activation in LPS-stimulated cells. LGG had immunomodulatory effects on LPS-induced porcine IECs by modulating TLR expressions and inhibiting MAPK and NF-κB signaling to decrease inflammatory cytokine expressions. Components of LGG exerted immunomodulatory effects on porcine IECs, especially immunostimulatory CpG oligodeoxynucleotides.