| Effect of Lactobacillus peptidoglycan (PG) on mice nonspecific immune response and cytokines production were studied both on physiology and gene expression level. PG recognition, signal pathways and targeted gene expression was also studied.Normal KM mice were injected (i.p.) with 200μL of PBS or PG (0.2 mg ml-1 or 1.0mg ml-1) for 3 consecutive days. It was found that serum lysozyme, hemolysin, alkaline phosphatase increased after both dose of PG administration. However, PG did not influence serum superoxide anion, asuperoxide dismutase (SOD) and peroxidase. PG induced the production of inflammatory cytokines (IL-1, TNF-αin peritoneal macrophages, IFN-γin spleen cell and MPO in small intestine) and did not induce the IL-10 production in peritoneal macrophages.Effect of PG on mice peritoneal and spleen cell gene expression was studied by using gene chip technology after mice were injected with PG once or for three times (one dose per day). The results revealed that the TLR2-NFB pathway was activated. Expression of TLR 2 was up regulated, activity of NF-kB1, NF-kB2 k and T cell nuclear factor was activated which resulted in expression of immune related genes. The Jak-Stat pathway was also activated, which might play a role in regulating inflammatory response.RT-PCR was used to further explore influence of PG in TLR-NF-kB pathway. It was found that expression of TLR2 was highly up regulated 2 hours after the last injection of three day of admonitions (i.p.), which became more significant after 4 hour and reached peak 12 hours later. Expression of Tollip was not changed. This implied that the down regulated pathway was activated which could prevent the over development of inflammatory response.
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