Background Salmonella typhimurium(S.T),as an important foodborne bacterial pathogen,can cause diarrhea and gastroenteritis in humans and animals.Numerous studies have confirmed that exopolysaccharides(EPSs)have variou...Background Salmonella typhimurium(S.T),as an important foodborne bacterial pathogen,can cause diarrhea and gastroenteritis in humans and animals.Numerous studies have confirmed that exopolysaccharides(EPSs)have various biological functions,but the mechanism through which EPSs improve the immunity of animals against the invasion of pathogenic bacteria is unclear.Here,we explored the protective effect of EPSs of Lactobacillus rhamnosus GG(LGG)on the S.T-infected intestine.Methods Mice received adequate food and drinking water for one week before the start of the experiment.After 7 d of prefeeding,2×108 CFU/mL S.T solution and an equivalent volume of saline(control group)were given orally for 1 d.On the fourth day,the mice were treated with 0.5 mg/mL EPSs,1.0 mg/mL EPSs,2.0 mg/mL EPSs,or 2.0 mg/mL penicillin for 7 d.Finally,the body and relative organ weight,histological staining,and the levels of antioxidant enzyme activity and inflammatory cytokines were determined.Results The S.T-infected mice exhibited symptoms of decreased appetite,somnolence,diarrhea and flagging spirit.Treatment with EPSs and penicillin improved the weight loss of the mice,and the high dose of EPSs showed the best therapeutic effect.EPSs significantly ameliorated S.T-induced ileal injury in mice.High-dose EPSs were more effective than penicillin for alleviating ileal oxidative damage induced by S.T.The mRNA levels of inflammatory cytokines in the ileum of mice showed that the regulatory effects of EPSs on inflammatory cytokines were better than those of penicillin.EPSs could inhibit the expression and activation of key proteins of the TLR4/NF-κB/MAPK pathway and thereby suppress the level of S.T-induced ileal inflammation.Conclusions EPSs attenuate S.T-induced immune responses by inhibiting the expression of key proteins in the TLR4/NF-κB/MAPK signaling pathway.Moreover,EPSs could promote bacterial aggregation into clusters,which may be a potential strategy for reducing the bacterial invasion of intestinal epithelial cells.展开更多
通过猪链球菌2型分解代谢控制蛋白A(catabolite control protein A,ccpA)原核表达蛋白对巨噬细胞RAW264.7进行刺激,结果发现,猪链球菌2型ccpA蛋白可以调节巨噬细胞NO产生,另外该蛋白质可通过对iNOS、NF-κB、p38和ERK1/2MAPK等的调节,...通过猪链球菌2型分解代谢控制蛋白A(catabolite control protein A,ccpA)原核表达蛋白对巨噬细胞RAW264.7进行刺激,结果发现,猪链球菌2型ccpA蛋白可以调节巨噬细胞NO产生,另外该蛋白质可通过对iNOS、NF-κB、p38和ERK1/2MAPK等的调节,从而影响巨噬细胞RAW264.7对细胞因子IL-6、TNF-α和IFN-γ的分泌。该研究为类似蛋白质对免疫细胞NF-κB/MAPK等通路调节影响及细胞因子产生条件探索建立了基础。展开更多
Two immunomodulatory polysaccharides(Vp2a-Ⅱ and Vp3) were isolated and identified from Apocynum venetum L. flowers, and their innate immune-stimulating functions and working mechanisms were evaluated in RAW264.7 cell...Two immunomodulatory polysaccharides(Vp2a-Ⅱ and Vp3) were isolated and identified from Apocynum venetum L. flowers, and their innate immune-stimulating functions and working mechanisms were evaluated in RAW264.7 cells. Both the level of released nitric oxide(NO) and expression of inducible nitric oxide synthase(iNOS) m RNA were significantly enhanced in the RAW264.7 macrophages cells treated by Vp2a-Ⅱ and Vp3. Vp2a-Ⅱ(100–800 μg/m L) and Vp3(400 μg/mL) could significantly increase the phagocytic activity of RAW264.7 cells and the secretion and m RNA expression of TNF-α and IL-6 in a concentrationdependent manner through affecting mitogen-activated protein kinase(MAPK) activity and nuclear factor κB(NF-κB) nuclear translocation. Vp2a-Ⅱ might activate the MAPK signaling pathways and induce the nuclear translocation of NF-κB p65, whilst Vp3 likely activated the NF-κB and MAPK signaling pathways without influencing the p38 MAPK route.展开更多
基金supported by the National Natural Science Foundation of China(32030101,32272914)the National Key R&D Program of China(2022YFD1300700)the Heilongjiang Touyan Innovation Team Program。
文摘Background Salmonella typhimurium(S.T),as an important foodborne bacterial pathogen,can cause diarrhea and gastroenteritis in humans and animals.Numerous studies have confirmed that exopolysaccharides(EPSs)have various biological functions,but the mechanism through which EPSs improve the immunity of animals against the invasion of pathogenic bacteria is unclear.Here,we explored the protective effect of EPSs of Lactobacillus rhamnosus GG(LGG)on the S.T-infected intestine.Methods Mice received adequate food and drinking water for one week before the start of the experiment.After 7 d of prefeeding,2×108 CFU/mL S.T solution and an equivalent volume of saline(control group)were given orally for 1 d.On the fourth day,the mice were treated with 0.5 mg/mL EPSs,1.0 mg/mL EPSs,2.0 mg/mL EPSs,or 2.0 mg/mL penicillin for 7 d.Finally,the body and relative organ weight,histological staining,and the levels of antioxidant enzyme activity and inflammatory cytokines were determined.Results The S.T-infected mice exhibited symptoms of decreased appetite,somnolence,diarrhea and flagging spirit.Treatment with EPSs and penicillin improved the weight loss of the mice,and the high dose of EPSs showed the best therapeutic effect.EPSs significantly ameliorated S.T-induced ileal injury in mice.High-dose EPSs were more effective than penicillin for alleviating ileal oxidative damage induced by S.T.The mRNA levels of inflammatory cytokines in the ileum of mice showed that the regulatory effects of EPSs on inflammatory cytokines were better than those of penicillin.EPSs could inhibit the expression and activation of key proteins of the TLR4/NF-κB/MAPK pathway and thereby suppress the level of S.T-induced ileal inflammation.Conclusions EPSs attenuate S.T-induced immune responses by inhibiting the expression of key proteins in the TLR4/NF-κB/MAPK signaling pathway.Moreover,EPSs could promote bacterial aggregation into clusters,which may be a potential strategy for reducing the bacterial invasion of intestinal epithelial cells.
文摘通过猪链球菌2型分解代谢控制蛋白A(catabolite control protein A,ccpA)原核表达蛋白对巨噬细胞RAW264.7进行刺激,结果发现,猪链球菌2型ccpA蛋白可以调节巨噬细胞NO产生,另外该蛋白质可通过对iNOS、NF-κB、p38和ERK1/2MAPK等的调节,从而影响巨噬细胞RAW264.7对细胞因子IL-6、TNF-α和IFN-γ的分泌。该研究为类似蛋白质对免疫细胞NF-κB/MAPK等通路调节影响及细胞因子产生条件探索建立了基础。
基金supported by Research on Precision Nutrition and Health Food,Department of Science and Technology of Henan Province(CXJD2021006)。
文摘Two immunomodulatory polysaccharides(Vp2a-Ⅱ and Vp3) were isolated and identified from Apocynum venetum L. flowers, and their innate immune-stimulating functions and working mechanisms were evaluated in RAW264.7 cells. Both the level of released nitric oxide(NO) and expression of inducible nitric oxide synthase(iNOS) m RNA were significantly enhanced in the RAW264.7 macrophages cells treated by Vp2a-Ⅱ and Vp3. Vp2a-Ⅱ(100–800 μg/m L) and Vp3(400 μg/mL) could significantly increase the phagocytic activity of RAW264.7 cells and the secretion and m RNA expression of TNF-α and IL-6 in a concentrationdependent manner through affecting mitogen-activated protein kinase(MAPK) activity and nuclear factor κB(NF-κB) nuclear translocation. Vp2a-Ⅱ might activate the MAPK signaling pathways and induce the nuclear translocation of NF-κB p65, whilst Vp3 likely activated the NF-κB and MAPK signaling pathways without influencing the p38 MAPK route.
