Immunomodulation and signaling mechanism of Lactobacillus rhamnosus GG and its components on porcine intestinal epithelial cells stimulated by lipopolysaccharide
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Background/purpose: This study aimed to evaluate the immunomodulatory effects and signaling mechanisms of Lactobacillus rhamnosus GG (LGG) and its components [surfacelayer protein (SLP), DNA, exopolysaccharides, and CpG oligodeoxynucleotides] on lipopolysaccharide (LPS)-stimulated porcine intestinal epithelial cell (IEC) IPEC-J2. Methods: The mRNA expressions of inflammatory cytokines and Toll-like receptors (TLRs) were measured by quantitative real-time polymerase chain reaction. Activation of mitogenactivated protein kinase (MAPK) and nuclear factor kappa B (NF-kB) signaling was detected by western blot and immunofluorescence. Results: 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-kB signaling activations. CpG oligodeoxynucleotides significantly increased the interleukin 12, tumor necrosis factor a, and TLR9 mRNA levels and enhanced NF-kB signaling activation in LPS-stimulated cells. Conclusion: LGG had immunomodulatory effects on LPS-induced porcine IECs by modulating TLR expressions and inhibiting MAPK and NF-kB signaling to decrease inflammatory cytokine expressions. Components of LGG exerted immunomodulatory effects on porcine IECs, especially immunostimulatory CpG oligodeoxynucleotides.