β-葡聚糖增强肠道免疫功能研究进展

肠道既是机体营养物质消化吸收的重要场所,又是防御外界病原体等的重要屏障,维持肠道稳态、增强肠道免疫功能对于保持机体健康至关重要。β-葡聚糖作为一种膳食纤维,同时也被列为益生元,具有众多生物活性和较强的免疫活性,如免疫调节、抗菌、抗炎等,尤其是可以通过直接或间接(肠道代谢物)途径参与重塑肠道菌群组成及比例,维持与修复肠道屏障完整性,调控免疫细胞,进而发挥增强肠道免疫作用。本文主要综述了β-葡聚糖通过增强肠道免疫的作用途径和机制,以及其发挥的生物学作用,为进一步阐明β-葡聚糖与机体肠道相互作用的功能网络提供理论基础。     

牡蛎肽肠内营养制剂对小鼠肠道功能作用的研究

本文主要探讨牡蛎肽肠内营养制剂对小鼠肠道功能的作用。将动物随机分为阴性对照组、阳性对照组和低、中、高剂量组5组,灌胃给予不同剂量牡蛎肽肠内营养制剂,每天测定各组体重和进食量,最后测定食物利用系数、小肠推进率、小肠吸收等评价指标。结果显示,与阴性对照组相比,低、中剂量组食物利用系数和小肠推进率均有明显增加,低剂量组木糖浓度明显增高。可见,牡蛎肽肠内营养制剂能促进小肠推进和消化吸收,可以作为肠内营养制剂应用于临床营养支持。     

Protein transport across the small intestine in food allergy

In view of the imminent deficiency of protein sources for human consumption in the near future, new protein sources need to be identified. However, safety issues such as the risk of allergenicity are often a bottleneck, due to the absence of predictive, validated and accepted methods for risk assessment. The current strategy to assess the allergenic potential of proteins focuses mainly on homology, stability and cross‐reactivity, although other factors such as intestinal transport might be of added value too. In this review, we present an overview of the knowledge of protein transport across the intestinal wall and the methods currently being used to measure this. A literature study reveals that protein transport in sensitised persons occurs para‐cellularly with the involvement of mast cells, and trans‐cellularly via enterocytes, while in non‐sensitised persons micro‐fold cells and enterocytes are considered most important. However, there is a lack of comparable systematic studies on transport of allergenic proteins. Knowledge of the multiple protein transport pathways and which model system can be useful to study these processes may be of added value in the risk assessment of food allergenicity.     

不同喂养方式对婴幼儿肠道菌群多样性影响的研究进展

近些年的研究发现婴幼儿肠道菌群与众多机体的病理相关,其肠道内栖息着数量巨大的微生物,其中占据主导地位的是细菌,其在维持内环境稳态、调节能量代谢等方面发挥着复杂的作用,因此,婴幼儿肠道微生态的合理建立尤为重要。影响婴幼儿肠道菌群的因素有很多,其中喂养方式对婴幼儿肠道菌群结构有明显的影响。关于喂养方式对婴幼儿肠道菌群多样性影响的研究甚少,故本文结合近些年国内外关于喂养方式与婴幼儿肠道菌群的研究,综述了婴幼儿肠道菌群的建立与演替,以及婴幼儿肠道菌群的生理功能,同时,讨论了不同喂养方式(母乳喂养、配方奶粉喂养、混合喂养)下婴幼儿肠道微生态的差异,以期为研发适用于婴幼儿喂养方式的研究中提供一定的理论指导依据。     

Protective effect of whey cheese matrix on probiotic strains exposed to simulated gastrointestinal conditions

A probiotic whey cheese added with Lactobacillus casei LAFTI®L26, Lactobacillus acidophilus LAFTI®L10 or Bifidobacterium animalis Bo was subject in vitro to sequential conditions that parallel the four major steps of digestion: mouth (artificial saliva), oesophagus-stomach (artificial gastric juice), duodenum (artificial intestinal juice) and ileum; its manufacture followed the traditional cheesemaking protocol of Portuguese Requeijão. MRS broth was inoculated in parallel as reference medium, to ascertain the protective effect of the whey cheese matrix itself upon those strains in every digestion step. Mouth conditions had an almost negligible effect upon all three strains, whereas oesophagus-stomach, duodenum and ileum conditions decreased the viable numbers of L. casei and L. acidophilus; in both systems, B. animalis suffered only slight decreases in viable numbers; and L. casei and L. acidophilus behaved likewise in MRS exposed to duodenum and ileum conditions. Whey cheese matrices thus appeared to protect the aforementioned three strains during transit throughout the simulated gastrointestinal system, so they are promising carriers of those probiotic bacteria.     

不同植物蛋白质对大鼠肠道菌群的影响

目的:以酪蛋白为参照,观察麦绿素、大豆蛋白和花生蛋白等3种植物蛋白质对生长期大鼠肠道菌群结构的影响。方法:生长期雄性SD大鼠36只,随机分为4组,分别饲喂含20%酪蛋白(酪蛋白组)、14%酪蛋白加6%麦绿素(麦绿素组)、20%大豆蛋白(大豆蛋白组)和20%花生蛋白(花生蛋白组)的人工半合成饲料,28d时连续收集7d的粪便,测干、湿质量,35d后经直肠取粪检测5种肠道常见菌群的数量。结果:3种植物蛋白组平均日排出粪便量均显著高于对照组;花生蛋白组日排出粪便湿重、粪便干重和粪便含水率均显著高于其它3组;花生蛋白组双歧杆菌数量显著增加,肠杆菌和产气荚膜梭菌数量显著减少,B/E值大幅上升。大豆蛋白组肠杆菌和肠球菌数量显著增加,B/E值显著降低。麦绿素组大鼠肠道菌群结构与酪蛋白组无显著差异,不同来源的蛋白质对乳杆菌数量影响不大。结论:花生蛋白对双歧杆菌有增殖效果,对大鼠肠道菌群有很好的调节作用。     

应用现代微生态学对我国传统固态白酒的生态评价

在有益剂量通过预实验确立的前提条件下,对30只180~200g雄性wistar大鼠饲养一周后进行分组,分别用不同剂量的传统固态白酒(低剂量1组2.8mL/kg、低剂量2组5.6mL/kg、高剂量1组11.2mL/kg、高剂量2组16.8mL/kg)、乙醇组2.8mL/kg、正常组,共6组每组5只,进行灌胃一个月、两个月后,每组随机取3只老鼠进行肠道微生态、肝肾功能和肠道屏障功能的影响进行评价,结果显示:纯粮固态白酒低剂量1组的高密度脂蛋白、总胆固醇、肝脏中的谷草转氨酶含量和结肠、肝脏组织HE染色评分均存在有益作用。     

Assessment of the lupin seed glucose-lowering protein intestinal absorption by using in vitro and ex vivo models

A lupin seed glycoprotein, termed γ-conglutin, has previously been found to display insulin-mimetic activity in myocyte models and reduce plasma glucose concentration when orally administered to both rats and humans. To envisage the possible metabolic fate of this bioactive protein, we used in vitro cell and ex vivo tissue models to monitor its transit through the intestinal barrier. Caco-2 cell monolayers and rat intestinal everted sacs were treated with purified γ-conglutin and the protein was immuno-assayed by chemi-luminescence-enhanced Western blotting. The in vitro approach showed that the intact protein can transit from the apical to the basolateral side of the cell monolayers. The unmodified lupin protein was also detected inside the intestinal everted sacs. Proper controls of cell monolayer and sac integrity ruled out the possibility of protein passive leakage.     

淡水鲈鱼小清蛋白致敏性及其对小鼠肠道菌群的影响

目的研究淡水鲈鱼小清蛋白(parvalbumin,PV)的致敏性,同时探索其对小鼠肠道菌群的影响。方法 36只C3H/HeJ小鼠按体重随机分为3组,分别为空白对照组(CK组)、卵清白蛋白(ovalbumin, OVA)致敏对照组(OVA组)和小清蛋白致敏组(PV组)。使用生理盐水、OVA溶液和PV溶液通过经口灌胃在6周时间内进行致敏,实验最后一天进行大剂量刺激,测定小鼠的体温变化、血清抗体水平和相关细胞因子水平,取腹腔灌洗液测定其中蛋白的含量以评价小鼠血管渗透性的变化,利用流式细胞术测定各组小鼠脾脏(SP)和肠系膜淋巴结(MLN)中T细胞亚群的水平。取小鼠粪便,对肠道菌群进行16S rRNA高通量测序,探索小清蛋白对小鼠肠道菌群的影响。结果与空白对照组相比,OVA小鼠血清抗体、细胞因子和免疫组织Th2相比水平均显著升高(P0.05),且表现出明显过敏症状。PV处理也使小鼠表现出明显的食物过敏症状,但仅显著升高了小鼠血清免疫球蛋白G1(Immunoglobulin G1, IgG1)和白细胞介素10(Interleukin 10, IL-10)的水平(P0.05)。16S rRNA高通量测序结果显示, OVA处理升高了小鼠肠道中属于拟杆菌门和变形菌门群落的水平,而PV处理升高了属于厚壁菌门菌群的丰度。结论淡水鲈鱼小清蛋白对小鼠具有一定的致敏性,但其致敏机理及对肠道菌群的影响作用与OVA不同。     

骆驼刺与刺糖水提物对小鼠肠推进作用的研究

目的研究骆驼刺与刺糖水提物对小鼠小肠运动的影响,为兽医临床防治动物胃肠道疾病筛选植物药及安全使用剂量选定提供依据。方法回流提取骆驼刺与刺糖水提剂,用硫酸阿托品与氯化氨甲酰甲胆碱分别建立抑制小肠运动和促进小肠运动的病理模型,骆驼刺及刺糖水提剂分别以高、中、低3种剂量给药,以葡聚糖蓝的推进距离与小肠总长的比值计算小肠推进率,观察骆驼刺及刺糖水提剂对小鼠小肠运动的影响。结果骆驼刺及刺糖水提物明显促进小鼠小肠运动的同时,拮抗阿托品对小肠运动的抑制,骆驼刺水提剂高、中、低剂量的促进率分别为22%、16.39%、16.07%,刺糖水提剂的促进率分别为30.83%、24.92%、25.12%。同时抑制氯化氨甲酰甲胆碱对小肠运动的促进作用,高、中、低剂量的骆驼刺水提剂抑制率分别为12.99%、23.2%、23.36%,刺糖水提剂的抑制率分别为8.61%、13.41%、27.47%。结论骆驼刺与刺糖水提剂对小鼠小肠运动具有双重调节作用。     

Physiological relevance of food grade microcapsules: Impact of milk protein based microcapsules on inflammation in mouse models for inflammatory bowel diseases

In order to increase beneficial effects of bioactive compounds in functional food and dietary supplements, enormous efforts are put in the technological development of microcapsules. Although these products are often tailor‐made for disease susceptible consumer, the physiological impact of microcapsule uptake on the respective target consumer has never been addressed. The present study aimed to assess the relevance of this aspect by analyzing the impact of milk protein based microcapsules on experimental inflammatory bowel disease. Long‐term feeding of sodium caseinate or rennet gel microcapsules resulted in significant alterations in the intestinal microbiota of healthy mice. In TNFΔARE/wt mice, a model for chronic ileal inflammation, rennet gel microcapsules resulted in further increased splenomegaly, whereas ileal inflammation was unchanged. In IL10^?/? mice, a model for chronic colitis, both types of microcapsules induced a local increase of the intestinal inflammation. The present study is the first to demonstrate that, independent of their cargo, microcapsules have the potential to affect the intestinal microbiota and to exert unprecedented detrimental effects on disease‐susceptible individuals. In conclusion, the impact of microcapsule uptake on the respective target consumer groups should be thoroughly investigated in advance to their commercial use in functional food or dietary supplements.     

一株章鱼肠道共生菌的筛选鉴定及抑菌谱研究

采用梯度稀释法从章鱼肠道筛选分离出一株具有抗菌作用的放线菌菌株D-8,通过该菌株的培养特征、生理生化特性、16S rDNA的Blast检索及系统发育分析表明,该菌株与链霉菌属具有99%以上的同源性,鉴定该菌株为链霉菌。同时对菌株D-8的发酵产物进行抗细菌、真菌活性检测。结果表明,该菌株对革兰氏阳性菌、革兰氏阴性菌及部分真菌都有抗菌活性,其活性化合物有待进一步研究。      

In-vitro assessment of the effects of dietary fibers on microbial fermentation and communities from large intestinal digesta of pigs

Dietary fibers (oat β-glucan, flaxseed gum, and fenugreek gum) can be fermented to short chain fatty acids (SCFAs) in batch cultures by pig intestinal digesta. Lactate in the β-glucan-grown cultures had the highest level among SCFAs produced, whereas flaxseed or fenugreek gum-containing cultures generated a significant amount of acetate, propionate and butyrate over three subcultures tested (p < 0.05). Denaturing gradient gel electrophoresis (DGGE) analysis of 16S rRNA genes in the initial and subcultures revealed that types of fibers impacted pronouncedly on the bacterial community structure. Identified DGGE DNA bands were mainly affiliated with Bacteroidetes, and Firmicutes, in which numbers of butyrate-producing species were widely distributed. The fermentability of dietary fibers to SCFAs and their selection towards the bacterial communities suggest their potential application in promoting animal/human health.     

长期食用铁皮石斛多糖对正常小鼠的影响

目的 对正常小鼠长期食用铁皮石斛多糖的安全性及功能性进行评价。方法 采用水提醇沉法提取铁皮石斛多糖。将16只雄性KM小鼠分为正常组及铁皮石斛多糖组,适应性喂养后,铁皮石斛多糖组小鼠按临床等效剂量灌胃8周,每天1次,每次0.4 mL,正常组小鼠灌胃等量无菌水,观察小鼠的生存情况、一般状况、定期记录体重及摄食量,灌胃结束后检测脏器指数及血脂四项,观察肠黏膜形态。结果 与正常组相比,铁皮石斛多糖组小鼠的体重增长率及摄食量下降,但无显著性差异,脏器指数、肠黏膜形态及血脂四项均无显著变化。结论 正常小鼠长期食用铁皮石斛多糖是安全的,但功效不明显,可能与正常机体的器官及功能处于平衡状态,无法很好的凸显铁皮石斛多糖的调节功能有关。     

Interaction of probiotic Lactobacillus and Bifidobacterium strains with human intestinal epithelial cells: adhesion properties, competition against enteropathogens and modulation of IL-8 production

The human intestinal microbiota plays a pivotal role in human nutrition and health by promoting the supply of nutrients, preventing pathogen colonization and shaping and maintaining normal mucosal immunity. The depletion of the individual microbiota can result in a higher susceptibility to enteropathogenic bacteria infection. In order to reduce this risk, the use of food supplements containing probiotic bacteria has been recently addressed. In this paper, we investigate the protective role toward enteropathogen infection of probiotic strains belonging to Lactobacillus and Bifidobacterium. According to our experimental data, Lactobacillus acidophilus Bar13, L. plantarum Bar10, Bifidobacterium longum Bar33 and B. lactis Bar30 were effective in displacing the enteropathogens Salmonella typhimurium and Escherichia coli H10407 from a Caco-2 cell layer. Moreover, L. acidophilus Bar13 and B. longum Bar33 have been assessed for their immunomodulatory activity on IL-8 production by HT29 cells. Both strains showed the potential to protect enterocytes from an acute inflammatory response. These probiotic strains are potential candidates for the development of new functional foods helpful in counteracting enteropathogen infections.