Protective Effect And Mechanism Of Selenium Supplementation On LPS-Induced Immunological Stress In Murine RAW264.7 Cells And Kunmin Mice

This study was conducted to determine whether difference levels Selenium(Se)supplementation could alleviates lipopolysaccharide(LPS)-induced immunological stress in mouse RAW264.7 cells or SPF Kunming mice and analysis its possible mechanism related to selenoprotein encoding genes.Experiment 1: Protective effect and mechanism of selenium supplementation on LPS-induced immunological stress in murine RAW264.7 cells.This study was conducted to profile selenoprotein encoding genes in mouse RAW264.7 cells upon lipopolysaccharide(LPS)challenge and integrate their roles into immunological regulation in response to Se pretreatment.LPS was used to develop immunological stress in macrophages.Cells were pretreated with different levels of selenite(0,0.5,1.0,15,2.0 ?mol Se/L,SS)for 2 h,followed by LPS(100 ng/m L)stimulation for another 3 h.The m RNA expression of 24 selenoprotein encoding genes and 9 inflammation-related genes were investigated.The results showed that: 1)LPS(100 ng/m L)effectively induced immunological stress in RAW264.7 cells with induced inflammation cytokines,IL-6 and TNF-?,m RNA expression and cellular secretion,and increased(P < 0.05)m RNA profiles of 9 inflammation-related genes in cells;2)LPS(100 ng/m L)decreased(P < 0.05)m RNA levels of 18 selenoprotein encoding genes and up-regulated m RNA levels of TXNRD1 and TXNRD3 in cells;3)Short-time Se pretreatment modestly reversed(P < 0.05)the LPS induced up-regulation of 7 genes(COX-2,ICAM-1,IL-1?,IL-6,IL-10,iNOS,and MCP-1)and further increased(P < 0.05)expression of IFN-? and TNF-? in stressed cells,1.5 ?mol/L Se exhibited the optimal protective effect;4)Meanwhile,Se pretreatment recovered(P < 0.05)expression of 3 selenoprotein encoding genes(GPX1,SELENOH and SELENOW)in a dose-dependent manner and increased(P < 0.05)expression of another 5 selenoprotein encoding genes(SELENOK,SELENOM,SELENOS,SELENOT and TXNRD2)only at a high level(2.0 ?mol Se/L)in stressed cells.Taken together,LPS induced immunological stress in RAW264.7 cells accompanied with the global down-regulation of selenoprotein encoding genes and Se pretreatment alleviated immunological stress via up-regulation of a subset of selenoprotein encoding genes(GPX1,SELENOH and SELENOW).Experiment 2: Effect of dietary Se O supplementation on LPS-induced immunological stress in Kunming mice and expression of selenoprotein encoding genes in liver and spleen.This study was conducted to determine whether a new type of organic Se(Se O)supplementation could alleviate lipopolysaccharide(LPS)-induced immunological stress in SPF Kunming mice and analysis its possible mechanism.A total of 90 3-w-old SPF kunmin mice(9.5-11 g)were randomly divided into 5 dietary treatments with 6 replicates and 3 mice per replicate.The five treatments are as following: control,LPS,0.15 mg Se/kg + LPS,0.30 mg Se/kg + LPS and 0.45 mg Se/kg + LPS.After 3 day's pre-fedding,the mice of control and LPS groups were feed on basal diet(BD,normal commercial feed for mice),other groups were feed on BD adding different levels of Se O.The mice were injected with LPS(3 mg/kg BW)at 14 d and 28 d and the control mice were injected with physiological saline.The mice were killed to collect plasma and tissue samples after 6h of injection at 28 d.The results are as follows:1)LPS effectively induced immunological stress in mice,which decreased(P < 0.05)the 21 d ADG of mice,induced oxidative stress in spleen,increased(P < 0.05)spleen index and inflammatory cytokines IL-6 and TNF-? levels in plasma,up-regulated(P < 0.05)expression of 8 inflammation-related genes(COX-2,ICAM-1,IL-1?,IL-6,IL-10,iNOS,MCP-1 and TNF-?)in liver and spleen;2)LPS induced immunological stress in mice accompanied with global down-regulation(P < 0.05)of 17 and 16 selenoprotein encoding genes in liver and spleen,respectively,and furhter up-regulated(P < 0.05)of 3 selenoprotein encoding genes in the two tissues;3)Dietary Se O supplementation alleviated(P < 0.05)immunological stress in mice challenged with LPS,compared to the LPS group,dietary Se O supplementation increased(P < 0.05)ADG of mice after LPS chllenege(14-21 d)and increased(P < 0.05)GSH-Px activity in spleen,decreased(P < 0.05)spleen index and inflammatory cytokines(IL-6 and TNF-?)in plasma,modestly down-regulated(P < 0.05)4 inflammation-genes(COX-2,IL-1?,TNF-? and iNOS)in liver,and 5 inflammation-genes(COX-2,ICAM-1,TNF-?,IL-6,and MCP-1)in the spleen,and further up-regulated(P < 0.05)3 inflammation-genes(IL-6,IL-10 and MCP-1)in liver,and 2 inflammation-genes(IL-10 and iNOS)in the spleen,0.3 mg Se/kg of Se O exhibited the optimal protective effect;4)Se O supplementation modestly up-regulated(P < 0.05)expression of 4 selenoprotein encoding genes(GPX1,SELENOF,SELENOM and SELENOT)in liver and 8 selenoprotein encoding genes(DIO2,GPX1,GPX3,SELENOF,SELENOI,SELENOK,SELENOS and SELENOT)in spleen of the stressed mice.Taken together,LPS induced immunological stress in mice accompanied with the global down-regulation of selenoprotein encoding genes in liver and spleen and dietary Se O supplementation alleviated immunological stress via up-regulation of a subset of selenoprotein encoding genes in coressponding tissues.