ABSTRACT
This chapter describes the study of the modulatory effects of Lactobacillus rhamnosus GG (LGG) on small intestinal immune cell signaling pathways in HGM-transplanted pigs vaccinated with an oral AttHRV vaccine. All LGG fed pigs had significantly higher IκBα level and p-p38/p38 ratio, while significantly lower p-ERK/ERK ratio than the non-LGG fed, AttHRV-vaccinated pigs, suggesting activation of regulatory signals during immune activation. LGG nine-dose- but not 14-dose-fed pigs had enhanced IL-6, IL-10, TNF-α, TLR9 mRNA levels, and p38 MAPK and ERK expressions in ileal mononuclear cells (MNC). Increased TLR9 mRNA was in parallel with higher mRNA levels of cytokines, p-NF-κB, and higher p-p38/p38 ratio in MNC of the low dose LGG fed pigs. Thus, LGG exerted divergent dose-dependent effects on the intestinal immune cell signaling pathway responses, with nine doses of LGG being more effective in activating the innate immunostimulating TLR9 signaling pathway than 14 doses in HGM pigs vaccinated with AttHRV. Stronger activation of cell signaling pathways and innate cytokines by lower dose LGG appears to be reversely correlated with its impact on IFN-γ producing effector T cell responses induced by the AttHRV vaccine.
