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Jejunal Peyer's patches contain specialized epithelial M cells that take up ingested microorganisms from the lumen of the gut by transcytosis. Using DNA-micro array, we analyzed the gene expression patterns of jejunal Peyer's patches in order to gain insight into the molecular mechanism by which Lp6 interacted with the host organism in a gnotobiotic environment v. in the gut normal microflora. The micro array data revealed that, among approximately 14,000 genes, 420 were expressed in Lp6 administration group at twofold or higher levels compared to the control group. These included genes involved in immune response, and cell differentiation, cell-cell signaling, cell adhesion, signal transcription, and transduction. Real-time PCR confirmed the reliability of the analysis. These data indicated that administration of Lactobacillus Lp6 was associated with a complex genetic response in the jejunal Peyer's patches.

To investigate the mechanism that Lactobacillus peptidoglycan modulates mice immune response.BALB/c mice were administrated (i.p.) with Lactobacillus peptidoglycan once or three times. Peritoneal macrophages and spleen lymphocytes were isolated for gene expression analysis using gene array. PathwayExplorer and GeneMAPP were used to explore significant pathway in database.The analysis resulted in five significant pathways: cytokine-cytokine receptor interaction, T helper cell surface molecules, ribosomal proteins, inflammatory response pathway and mm heme biosynthesis.Lactobacillus peptidoglycan induced expression of considerable genes, which related to protective immune response and activation of Th cells. The induced immune response might be Th1 type.

The ingestion of lactobacilli is of great importance for the probiotic effect of host gut Peyer's patches (PPs) macrophages. The present study is in time focus on the investigation of the factors determining the ingestion of lactobacilli by PPs macrophages. Physicochemical properties of cell surface and adhesive property of nine Lactobacillus strains were examined in the present work. The association of the bacteria with PPs macrophage was checked with macrophage monolayers on coverslips. The influence of lactobacilli on macrophages phagocytic capacity was also investigated with a neutral red uptake assay in vitro. The results show that the macrophages could ingest lactobacilli in a strain dependent manner, and the most ingested strain is L. plantarum Lp6 compared to other tested strains, which displayed strain specific enhancement on the phagocytic activity of PPs macrophages. And there is no correlation between the physicochemical or adhesive properties of the cell surface and the ingestion. The association of L. plantarum Lp6 with PPs macrophage could be decreased by Protease K treatment. Surface proteins of L. plantarum Lp6 could promote the ingestion of fluorescent latex beads by PPs macrophages. In conclusion, the hydrophobicity of the cell surface might not be the key factor determining the association of lactobacilli with PPs macrophages. Cell surface proteins are the media for the binding L. plantarum Lp6 to macrophages.