乳酸菌Z222产胞外多糖(EPSⅠ)对免疫细胞功能的影响

目的　检测乳酸菌Z2 2 2 产胞外多糖EPSⅠ对体外免疫细胞功能的调节作用。方法　不同浓度的EPSⅠ作用于小鼠的腹腔巨噬细胞和脾细胞 ,分别用中性红染色法检测巨噬细胞的吞噬能力 ,用MTT法检测淋巴细胞在体外的转化能力、NK细胞杀伤肿瘤细胞Yac 1的能力和产细胞因子IL 2的活性。结果　 (1)EPSⅠ单独作用小鼠脾细胞就能促进体外淋巴细胞增殖 ,且表现出剂量依赖关系。EPSⅠ亦可促进ConA诱导的体外小鼠淋巴细胞转化。 (2 )EPSⅠ体外作用于小鼠腹腔巨噬细胞均可提高MΦ的吞噬能力 ,与对照组比较差异都有显著性。 (3)与对照组相比EPSⅠ能增加体外NK细胞的活性 ,杀伤率最大值达 6 2 .4 1%± 2 .5 4 %。 (4 )EPSⅠ使小鼠脾细胞产IL 2的能力与对照组比较 ,差异有显著性。结论　乳酸菌多糖EPSⅠ对小鼠的免疫功能有一定的调节作用。     

一种根瘤菌胞外多糖对小鼠免疫功能的影响

目的研究一种根瘤菌胞外多糖(REPS)对正常小鼠免疫功能的影响。方法将该多糖以大、中、小3个剂量[(40、20、10 mg/(Kg.d)]给小鼠连续腹腔注射(ip)10 d,测定胸腺质量、脾脏质量、碳粒廓清指数、血清抗绵羊红细胞(SRBC)抗体凝集效价和淋巴细胞转化值。结果与对照组比较,该多糖使小鼠脾脏质量明显增加,单核吞噬细胞的吞噬能力显著增强,提高了血清抗SRBC抗体凝集效价,增强了小鼠脾淋巴细胞转化功能。结论此根瘤菌胞外多糖对小鼠的非特异性和特异性免疫功能均有明显的增强作用。     

Interplay between extracellular matrix components of Pseudomonas putida biofilms

The extracellular matrix of bacterial biofilms has at least two key functions: to serve as a structural scaffold for the multicellular community, and to play a protective role against external stress. In this work, we report a compensatory effect whereby Pseudomonas putida reacts to the lack of either of the two main surface proteins involved in biofilm formation, LapA and LapF, by increasing expression and production of a species-specific EPS. Elevated levels of the second messenger molecule cyclic di-GMP alter the balance of extracellular matrix components, and the phenotypes of lapA and lapF mutants under these conditions are indicative of direct interactions taking place between large secreted proteins and exopolysaccharides. Our data suggest the existence of a mechanism by which bacteria would sense alterations in the composition of the extracellular matrix, leading to changes in expression of the different elements.     

csn2基因缺失对变异链球菌饥饿耐受和寡营养环境下胞外多糖合成的影响

目的探索csn2基因缺失对变异链球菌(Streptococcus mutans,Sm)饥饿耐受和寡营养环境下胞外多糖合成的影响。方法培养Sm csn2基因的缺失菌株及回补菌株,通过设置不同浓度梯度培养基创造寡营养生长环境供其生长。生长曲线检测寡营养生长环境下Sm的生长,结晶紫染色,扫描电镜、激光共聚焦显微镜检测寡营养生长环境下Sm的生物膜表型,蒽酮硫酸法检测Sm生物膜中胞外多糖的量,实时荧光定量PCR检测胞外多糖合成相关基因的表达。结果生长曲线结果显示csn2基因缺失抑制了饥饿胁迫下Sm的生长,激光扫描共聚焦显微镜检测结果显示野生型菌株、csn2基因缺陷株、回补菌株在营养充足培养条件下所得生物膜胞外多糖/细菌比值为0.44±0.07、1.05±0.13和0.57±0.08,在寡营养条件下所得生物膜胞外多糖/细菌比值为0.93±0.24、3.05±0.21和1.32±0.46,表明csn2基因缺失增强了Sm在寡营养环境下胞外多糖的合成能力;在饥饿胁迫下,胞外多糖合成相关基因gtfB、gtfC的表达水平分别显示出2.5和1.8倍的增加,gtfD的表达水平下调2/3。结论csn2基因对Sm的生理功能及毒力特性表现出多种影响,包括饥饿耐受和胞外多糖合成,这些改变可能与csn2基因缺失引发复杂的调控网络相关。     

Effect of arginine on the growth and biofilm formation of oral bacteria

BackgroundAlkali production via arginine deiminase system (ADS) of oral bacteria plays a significant role in oral ecology, pH homeostasis and inhibition of dental caries. ADS activity in dental plaque varies greatly between individuals, which may profoundly affect their susceptibility to caries.ObjectiveTo investigate the effect of arginine on the growth and biofilm formation of oral bacteria.Methods and resultsPolymicrobial dental biofilms derived from saliva were formed in a high-throughput active attachment biofilm model and l-arginine (Arg) was shown to reduce the colony forming units (CFU) counts of such biofilms grown for various periods or biofilms derived from saliva of subjects with different caries status. Arg hardly disturbed bacterial growth of Streptococcus mutans, Streptococcus sobrinus, Streptococcus sanguinis and Streptococcus gordonii in BHI medium, but only inhibited biofilm formation of S. mutans. Scanning electron microscope (SEM) showed S. mutans biofilms harboured fewer cells grown with Arg than that without Arg, even in the initial 2 h and 8 h phase. Confocal laser scanning microscope (CLSM) images of poly-microbial dental and S. mutans biofilms revealed the biofilms grown with Arg had lower exopolysaccharide (EPS)/bacteria ratios than those without Arg (P = 0.004, 0.002, respectively). Arg could significantly reduce the production of water-insoluble EPS in S. mutans biofilms (P < 0.001); however, quantitative real-time PCR (qRT-PCR) did not show significantly influence in gene expression of gtfB, gtfC or gtfD (P = 0.32, 0.06, 0.44 respectively).ConclusionsArg could reduce the biomass of poly-microbial dental biofilms and S. mutans biofilms, which may be due to the impact of Arg on water-insoluble EPS. Considering the contribution to pH homeostasis in dental biofilms, Arg may serve as an important agent keeping oral biofilms healthy thus prevent dental caries.     

AL-1与抗生素联用对绿脓杆菌胞外多糖和蛋白水解酶的影响

目的探讨穿心莲内酯衍生物AL-1与阿奇霉素、红霉素、环丙沙星和磷霉素联合用药对绿脓杆菌胞外多糖和蛋白水解酶的影响。方法运用激光共聚焦显微镜观察各抗生素单用及和AL-1联用对PA胞外多糖的形成的影响;应用紫外可见分光光度计检测各抗生素单用及与AL-1联用对PA胞外蛋白水解酶含量的影响。结果 AL-1与抗生素联用可抑制PA胞外多糖形成及降低PA胞外蛋白水解酶含量,且效果强于AL-1与各抗生素的单独作用。结论 AL-1对各抗生素抑制PA胞外多糖的形成及减少胞外蛋白水解酶的含量具有协同作用。     

Exopolysaccharide from Lacticaseibacillus rhamnosus induces IgA production in airways and alleviates allergic airway inflammation in mouse model

The currently observed high prevalence of allergic diseases has been associated with changes in microbial exposure in industrialized countries. Defined bacterial components represent a new strategy for modulating the allergic immune response. We show that intranasal administration of exopolysaccharide (EPS) isolated from Lacticaseibacillus (L.) rhamnosus LOCK900 induces TGF-β1, IgA, and regulatory FoxP3⁺ T-cells in the lungs of naïve mice. Using the ovalbumin mouse model, we demonstrate that intranasal administration of EPS downregulates the development of allergic airway inflammation and the Th2 cytokine response in sensitized individuals. At the same time, EPS treatment of sensitized mice, similar to EPS-induced responses in naïve mice, significantly increased the level of total, OVA-specific, and also bacteria-specific IgA in bronchoalveolar lavage and the number of IgA-producing B-cells in the lung tissue of these mice. Thus, EPS derived from L. rhamnosus LOCK900 can be considered a safe candidate for preventing the development of allergic symptoms in the lungs of sensitized individuals upon exposure to an allergen.     

Systemic Effects on Bone Healing of a New Hyaluronic Acid-Like Bacterial Exopolysaccharide

Critical Size Defect (CSD) technique was used to evaluate the systemic activities on bone regeneration capacity of a newly discovered hyaluronic acid-like exopolysaccharide synthesized by a bacteria originating from a deep sea hydrothermal vent. Some systemic effects were previously detected on earlier experiments. A 5 mm diameter hole was made on each parietal bone of male rats. The right hole was filled with 0.5 mg of a new bacterial exopolysaccharide referenced HE 800, while the left hole remained free of any treatment. After 21 days, the holes and surrounding tissues were examined by direct examination, X-rays, and histological staining. Using HE 800, bone healing was almost complete after only 21 days in the treated hole and always complete in the control side by some systemic effect. Neovascularization was also observed along with an organized trabecular bone on both sides. No abnormal bone growth or conjunctival abnormalities were noticed. At the end of the experiment, 90.1% (±5.2) bone healing (n = 20) was observed on the treated side; conversely, the control side animals demonstrate an amazing healing 100% (±0.5) by a systemic effect.     

Inhibition of the adhesion to catheters of uropathogenic Escherichia coli by sub-inhibitory concentrations of cefotaxime

Objective

To investigate the effect of sub-inhibitory concentrations of cefotaxime on adherence to siliconised latex urinary catheters of uropathogenic Escherichia coli strains from pregnant and non pregnant patients.

Study design

Using random sampling, 30 E. coli strains were selected from hospitalized patients with catheter associated urinary tract infection, 12 from pregnant women and 18 from men and non-pregnant women. The strains were categorized on the basis of cefotaxime susceptibility, adhesion and biofilm production capacity, cell surface hydrophobicity and expression of adhesins and fimbriae in vitro.

Results

The overall results indicated that sub-inhibitory concentrations of cefotaxime could reduce the adhesiveness, the biofilm production and hence, potentially, the infection rate associated with indwelling urinary catheters.

Conclusion

Based on our results, we propose that this reduction is due to decreasing exopolysaccharide production and increasing cell surface hydrophobicity of E.coli strains.     

一种红树林链霉菌的胞外多糖免疫功能研究

目的:对一种分离自海南红树林链霉菌的胞外多糖(exopolysaccharide,EPS)进行了免疫调节活性研究。方法:以小鼠迟发型过敏反应、血清溶血素测定以及巨噬细胞吞噬实验探讨EPS的免疫调节活性,并以流式细胞仪测定脾脏淋巴细胞亚群。结果:EPS对小鼠免疫应答多项指标具有一定的正向调节作用(P﹤0.05);CD4+T细胞数量、CD4+/CD8+比率明显高于正常对照组。结论:此种产自链霉菌的EPS具有一定的免疫调节活性。