Immunonmodulation And Mechanism Of Lactobacilli On Intestinal Inflammation Induced By Lipopolysaccharides

III Lactobacilli are widely used for maintaining animal intestinal health.Intestine of piglet is always expose to lots of stress,probiotics play an important role in modulation stabilization of the intestinal.Therefore,it is important to clarify how Lactobacilli function in modulating immune responses and to analyze key molecular in cell signaling transduction during Lactobacilli-intestine interaction.It is necessary to select probiotics Lactobacillis to benefit intestinal health of piglets.The aim of this study is to evaluate the immunomodulatory effects and signalling mechanisms of Lactobacillus rhamnosus GG(LGG).Piglets were pretreated with lactobacillus at dosage of 1010 CFU/d for two weeks then were i.p.with LPS to induce inflammation with the aim to evulate the modulation of lactobacilli on inflammation.In another experiment,C57BL/6 mice were pretreated with 108 CFU/m L LGG then stimulated with LPS.The piglets and mice intesintal tissues were measured by q RT-PCR.The activations of MAPK and NF-κB signalings were detected by western blotting and immunohistochemistry.The gut microbiome was analyzed by high-throughput sequencing.Metabolites were determined by GC-TOF-MS,at the same time,the role of lactobacillus was evaluate on regulation of metabolic pathways in the intestinal tract.Compared with LPS stimulation alone group,pretreatment of piglets with LGG significantly alleviated LPS-induced inflammatory cytokines(IL-6,IL-12 and TNF-α).Compared with the control,LPS stimulation induced a significantly higher P38 and ERK1/2 phosphorylation ratio and NF-κBp65 level,whereas a significantly lower IκBα level in the ileum by western blot.The feeding of LGG alleviated the activation of signal pathway and restored the content of p-P38/P38,ERK1/2,NF-κBp65 and IκBα to the normal level in ileum.Immunohistochemistry for p38,p-p38,ERK,p-ERK and IκBα in ileal tissue verified the result of western blot.In genus level,LGG reduced the proportion of Clostridium sense stricto 1,Streptococcus and Lactobacillus compared with the LPS group.In phylum level,LGG decreased the proportion of firmicutes and increase the proportion of Proteobacteria.For NF-κB knockout mice,compared with LPS stimulation alone group,pretreatment of mice with 108 CFU/m L LGG decreased LPS-induced inflammatory cytokines(IL-6 and TNF-α)and increased anti-inflammatory crytokines(IL-10),which is contrary to p38-knockout mice.Compared with LPS stimulation alone group,LGG also increased LPS-induced MAPK andNF-κB signalings activations in B6 mice and NF-κB-knockout mice.The results showed that LGG inhibited LPS-induced MAPK and NF-κB signalling and decreased the expression of pro-inflammatory cytokines including IL-6,TNF-α and IL-10,which indicated that LGG could alleviate inflammation induced by LPS in the IECs of porcine and mice models.