多黏菌素E诱导肠道菌群失调对肠屏障功能和细菌易位的影响

目的:应用多黏菌素E给小鼠灌胃诱导建立肠道菌群失调动物模型,研究肠道菌群失调对肠黏膜屏障和细菌易位的影响。方法:将20只小鼠随机分为两组,每组10只。实验组采用多黏菌素E按0.2 g/kg加入0.2 ml等渗盐水灌胃,1次/d,连续7 d。对照组用等剂量等渗盐水灌胃,1次/d,连续7 d。实验结束次日观察两组小鼠回肠黏膜病理形态、肠道菌群、回肠黏膜组织紧密连接(TJ)蛋白表达和器官(肝、脾、肾、淋巴结)细菌易位率等。结果:实验组小鼠盲肠黏膜和盲肠内容物的肠杆菌数量显著减少。常规病理检查发现,实验组小鼠回肠黏膜充血明显,绒毛稀疏,尖端有少量上皮坏死脱落,与对照组比损伤明显。透射电镜显示,实验组小鼠回肠上皮TJ的电子致密物质明显减少,TJ破坏。回肠黏膜组织中TJ蛋白Claudin-1、Occludin和ZO-1的表达显著下降,器官细菌易位率显著高于对照组。结论:多黏菌素E灌胃能够诱导肠道菌群失调,且导致肠屏障功能损伤和细菌易位。     

壳聚糖对小鼠肠道菌群的影响

「目的」观察壳聚糖对小鼠肠道菌群的影响。「方法」取昆明种小鼠２０只,随机分为观察组和对照组,分别灌胃壳聚糖的冰醋酸溶液４００ｍｇ／ｋｇ．ｄ和０．５％冰醋酸,连续七天,而后检测两组肠道菌群的变化。「结果」观察组双歧杆菌、乳杆菌数量比对照组明显增多（Ｐ〈０．０５）,大肠杆菌、肠球菌数量在两组间无明显改变。「结论」２％的壳聚糖溶液能促进双歧杆菌、乳杆菌的增殖。     

预防性应用类高血糖素多肽-Ⅱ对缺血-再灌注肠黏膜屏障的影响

目的:观察类高血糖素多肽-Ⅱ(GLP-Ⅱ)对缺血-再灌注所致的肠黏膜屏障损害的预防保护作用.方法:采用夹闭肠系膜上动脉20 min所致肠道缺血-再灌注损伤小鼠模型,将30只小鼠随机分为正常(N)组、对照(C)组和GLP-Ⅱ预处理(P)组.观察缺血-再灌注后1天,肠黏膜形态、肠道细菌移位率、血浆内毒素水平和肠道IgA浓度的变化,并进行相关分析.结果:缺血-再灌注后,C组肠黏膜受到明显损伤,P组肠黏膜增生明显,C组和P组小鼠的肠道细菌移位率和血浆内毒素水平均明显高于N组(P＜0.01),肠道IgA浓度则明显降低(P＜0.01).与C组相比,P组的细菌移位率和内毒素水平要低于C组(P=0.005),IgA浓度要高于C组(P＜0.01).结论:缺血-再灌注严重损害了肠黏膜屏障,经GLP-Ⅱ预处理可以有效地减轻肠黏膜屏障的损伤.     

结直肠癌患者术后肠道菌群变化及微生态制剂治疗效果研究

目的:探讨结直肠手术对结直肠癌患者肠道菌群的影响及微生态制剂治疗肠道菌群失调的效果.方法:选择50例结直肠癌择期手术患者随机分为微生态组和对照组各25例,术后对照组常规处理,微生态组给予三联活菌制剂口服治疗,采用细菌DNA PCR分析定量肠道细菌量,检测血浆D-乳酸和尿L/M水平,对比手术前后肠道菌群变化和肠道屏障功能.结果:术后10天双歧杆菌、乳酸杆菌显著降低,而微生态组显著高于对照组,大肠杆菌、粪肠球菌显著升高,微生态组显著低于对照组,B/E呈显著倒置,对照组倒置更为显著(P值＜0.05);术后60天,微生态组双歧杆菌、乳酸杆菌、大肠杆菌、粪肠球菌量及B/E基本恢复术前水平,而对照组仍显著低于术前(P值＜0.05).术后1天血浆D-乳酸和尿L/M水平显著升高(P值＜0.05),术后10天两组血浆D-乳酸和尿L/M水平均回落,微生态组回落较对照组显著且显著低于对照组(P值＜0.05).结论:结直肠癌术后患者肠道内双歧杆菌、乳酸杆菌等益生菌显著减少,大肠杆菌和粪肠球菌显著增加,肠道菌群严重失调,肠道屏障功能受损,微生态制剂治疗有助重建肠道菌群平衡,恢复肠道屏障功能.     

迁延性腹泻患儿肠道菌群分布和肠黏膜屏障功能变化

目的分析迁延性腹泻患儿肠道菌群分布和肠黏膜屏障功能变化,为迁延性腹泻的防治提供参考。方法选取2017年1月-2019年1月金华市人民医院收治的47例迁延性腹泻患儿为迁延性腹泻组,36例急性腹泻患儿为急性腹泻组,38例健康幼儿为正常对照组。比较3组粪便双歧杆菌、乳酸杆菌、大肠杆菌数量,计算双歧杆菌/大肠杆菌比值;比较3组血清细菌内毒素、二胺氧化酶、D-乳酸水平。结果 3组血清细菌内毒素、二胺氧化酶、D-乳酸水平比较差异均有统计学意义(均P0.05)。急性腹泻组、迁延性腹泻组血清细菌内毒素、二胺氧化酶、D-乳酸水平均显著高于正常对照组(均P0.05)。急性腹泻组和迁延性腹泻组血清细菌内毒素、二胺氧化酶、D-乳酸水平比较差异均无统计学意义(均P0.05)。3组双歧杆菌、乳酸杆菌、大肠杆菌数量及双歧杆菌/大肠杆菌比值比较差异均有统计学意义(均P0.05)。在正常对照组、急性腹泻组、迁延性腹泻组,双歧杆菌、乳酸杆菌数量及双歧杆菌/大肠杆菌比值依次降低,大肠杆菌数量依次升高,差异均有统计学意义(均P0.05)。结论迁延性腹泻与肠道微生态失衡、菌群紊乱及肠黏膜屏障功能损伤关系密切。     

利用生物发光活体成像技术观察肠黏膜损伤状态下细菌易位的初步研究

[目的]临床上各种疾病会导致肠黏膜屏障损伤并伴随大量的细菌易位发生。本实验拟使用发光细菌的小鼠活体成像技术,观察肠黏膜损伤状态下易位细菌的动态移位过程。[方法]构建重组荧光脂酶基因(Lux)的质粒pXen-1、pXen-18,转化大肠杆菌DH5a,筛选阳性细菌克隆,扩增培养后,定量(107)注射到肠黏膜屏障损伤模型小鼠肠腔不同部位内,利用生物发光活体成像技术进行细菌易位的病理生理观察研究。实验分为四组:小肠注射菌实验组和对照组、盲肠注射菌实验组和对照组。其中实验组为肠道缺血再灌注损伤,对照组无任何干预措施。[结果]发光细菌小鼠活体成像观察到,存在肠黏膜损伤的小鼠肠腔内的细菌数量及分布发生明显的改变,提示细菌易位在肠黏膜损伤时起着重要的病理生理作用。注入小肠内的发光细菌数量在试验过程中明显下降,提示小肠肠腔环境可以杀灭一定的细菌。[结论]生物发光活体成像技术,可以直观、可靠、敏感地观察肠道内细菌的存活状态,并可观察肠黏膜损伤状态下细菌易位的动态过程。该技术为肠黏膜屏障损伤细菌易位机制的研究提供了一个有力的工具。     

嗜酸乳杆菌NCFM和乳双歧杆菌HN019联用对小鼠肠道菌群的调节作用

目的探究嗜酸乳杆菌NCFM和乳双歧杆菌HN019联用对Balb/c小鼠肠道菌群的调节作用。方法使用低、中、高剂量的嗜酸乳杆菌NCFM和乳双歧杆菌HN019混合菌粉灌胃雄性Balb/c小鼠14 d,收集0、7、14 d小鼠粪便,梯度稀释后平板培养计数粪便中双歧杆菌、乳杆菌、肠杆菌、肠球菌、产气荚膜梭菌的数量以及双歧杆菌与肠杆菌的比值(B/E值)。结果益生菌低剂量组小鼠第7天肠道双歧杆菌、乳杆菌数量显著高于基质对照组(P0.05);低、中剂量组小鼠第7天肠道产气荚膜梭菌数量显著低于干预前(P0.05);高剂量组小鼠肠道B/E值显著高于空白对照组和基质对照组(P0.05)。结论嗜酸乳杆菌NCFM和乳双歧杆菌HN019联用对Balb/c小鼠肠道菌群具有很好的调节作用。     

发酵莲子乳对小鼠肠粘膜屏障保护作用

目的 验证发酵莲子乳(Lotus-milk Fermented Production,LMFP)保护小鼠肠粘膜屏障功效,并探讨可能的作用机制.方法 将60只清洁级ICR小鼠随机分为5组:阴性对照组和模型组给予蒸馏水,发酵莲子乳组、莲子匀浆组、发酵乳组,分别给予相应干预物.未次灌胃后腹腔注射细菌脂多糖(LPS)6 mg/(kg·bw),阴性对照组给予等体积/体重蒸馏水,18 h后处死小鼠,采集样本检测指标.结果 与阴性对照组比较,各组小鼠均出现不同程度的萎靡症状.甚至死亡,其中模型组最严重,发酵莲子乳组症状最轻;与模型组比较,发酵莲子乳可明显升高小鼠外周血白细胞总数和肠道分泌型免疫球蛋白A(SIgA)含量(P<0.001,P=0.001),有效维持肠道内乳酸杆菌菌量(P<0.001),降低LPS所升高的血浆肿瘤坏死因子-a(NF-a)水平(P=0.01),抑制大肠埃希菌过度繁殖(P=0.001),且发酵莲子乳功效优于发酵乳,而莲子匀浆无保护作用.结论 利用LPS腹腔注射小鼠成功建立肠粘膜损伤屏障模型,发酵莲子乳可通过维持肠道菌群稳定,增强肠道免疫机能等方式修复肠粘膜屏障损伤,减轻全身炎症反应程度.     

全肠外营养相关肠黏膜免疫屏障损伤小鼠模型的建立

目的:建立一种稳定有效的小鼠模型,为进一步研究全肠外营养(TPN)相关肠黏膜屏障损伤的机制和干预措施。方法:将22只小鼠随机分为对照组(n=10)和TPN组(n=12)。小鼠经颈内静脉置管后,对照组给予正常饮食,用微量泵持续输注等渗盐水;TPN组给予禁食后用微量泵持续输注PN液。5 d后比较两组小鼠生存率、肠道菌群易位情况、肠道杯状细胞数量以及潘氏细胞变化。结果:两组小鼠的生存率无显著性差异。TPN组肠道菌群淋巴结易位率增加(6/10 vs 1/10,P0.05),杯状细胞数量减少[(61.6±6.5)个vs(33.0±7.8)个,P0.01)],隐窝处潘氏细胞内抗菌多肽颗粒明显减少,溶菌酶和黏蛋白2(MUC2)含量显著降低。结论:TPN组小鼠能作为后期研究TPN诱导肠黏膜免疫屏障受损的模型,用于患病机制、药物治疗的观察和研究。     

艾司洛尔对脓毒症大鼠肠黏膜屏障的影响

目的:探讨艾司洛尔对脓毒症大鼠肠黏膜屏障的保护作用. 方法:建立脓毒症大鼠模型,将大鼠随机分为对照组(脓毒症组)和艾司洛尔组(脓毒症模型+艾司洛尔组),每组8只.观察大鼠的基本生命体征、体外肠道的通透性和血清内毒素变化.同时,通过肝、脾和肠系膜淋巴结细菌培养观察细菌易位情况.最后,根据H-E染色结果评估大鼠肠道损伤. 结果:艾司洛尔组大鼠心率明显低于基础值(P＜0.05).与对照组比,艾司洛尔组大鼠细菌易位减少,体外肠道通透性降低.两组大鼠血清内毒素水平无显著性差异.艾司洛尔组大鼠肠道病理评分明显低于对照组. 结论:艾司洛尔能保护脓毒症大鼠肠黏膜屏障,减轻肠损伤.     

Bulk prevents bacterial translocation induced by the oral administration of total parenteral nutrition solution

The effects of a fat and glutamine-free orally administered total parenteral nutrition (TPN) solution on intestinal mucosal mass, morphology, barrier function, and cecal bacterial population levels were measured in CD-1 mice. Ileal mucosal protein content decreased by 63% (p less than 0.01) in the oral TPN-fed mice, although they gained weight on this diet. These TPN-fed mice also exhibited changes in mucosal structure and the normal ecology of their cecal microflora was disrupted leading to overgrowth with Gram-negative enteric bacilli. These changes in intestinal mucosal mass, morphology, and gut bacterial ecology were associated with an increased incidence of bacterial translocation (BT) (TPN group 70% BT vs control group 15% BT: p less than 0.01). The administration of cellulose fiber or kaolin (bulk-forming agents), but not of citrus-pectin (a fully-fermentable, nonresidue fiber) reduced the incidence of BT in the TPN-fed mice to control levels. The beneficial effects of these bulk-forming agents appeared to be due to their ability to prevent TPN-induced disruption of the intestinal microflora and alterations in intestinal morphology, even though they did not prevent ileal mucosal protein levels from decreasing. These results suggest that the administration of bulk forming agents will prevent the loss of intestinal barrier function against luminal bacteria that occurs in mice fed an oral TPN solution.     

大黄和早期肠内营养对肠缺血-再灌注损伤大鼠肠屏障功能的影响

目的:观察大黄和早期肠内营养(EEN)对大鼠肠缺血-再灌注损伤(IRI)后肠黏膜屏障的影响.方法:将32只大鼠随机分为对照组、EN组、大黄组、大黄+EN组.在大鼠肠IRI模型上观察再灌注24h后肠黏膜形态学的变化、血清内毒素和细菌易位指标. 结果:肠IRI可导致肠黏膜发生严重损伤.肠IRI后24h,大黄组大鼠内毒素水平...     

Effect of oral genistein and isoflavone-free diet on cecal flora and bacterial translocation in antibiotic-treated mice

BACKGROUND: There are several reports indicating that the isoflavone genistein may augment the integrity of the intestinal epithelial barrier as well inhibit bacterial internalization by cultured enterocytes. We speculated that oral genistein might enhance the integrity of the intestinal epithelial barrier as monitored by the extraintestinal dissemination of intestinal bacteria. METHODS: Mice were treated with oral antibiotics to induce cecal bacterial overgrowth accompanied by bacterial translocation of antibiotic-resistant enterobacteria, especially Escherichia coli. These mice were divided into separate groups that included chow-fed mice orally inoculated either with saline, vehicle, or genistein, and mice fed isoflavone-free diet and orally inoculated with either saline, vehicle, or genistein. Intestinal bacterial overgrowth was monitored by quantitative culture of excised ceca and bacterial translocation was monitored by quantitative culture of draining mesenteric lymph nodes. RESULTS: Mice fed the isoflavone-free diet had decreased populations of cecal bacteria compared with chow-fed mice, and bacterial translocation was reduced in chow-fed mice compared with mice fed isoflavone-free diet. However, bacterial translocation was similar in mice given oral genistein compared with appropriate control mice. CONCLUSIONS: Oral genistein had no noticeable effect on bacterial translocation in this model. However, the isoflavone-free diet had an antibacterial effect on cecal flora, and the isoflavone-free diet was associated with decreased numbers of cecal bacteria and decreased incidence of bacterial translocation.     

乳杆菌黏附肠上皮样细胞HT-29对微丝骨架的影响

目的:研究乳杆菌黏附肠上皮样细胞HT-29后对单层细胞通透性和细胞微丝骨架的影响.方法:采用伊文斯蓝标记的清蛋白和荧光素标记的鬼笔环肽与乳杆菌黏附后的细胞共同孵育,测定细胞培养液的A620和荧光显微镜下观察细胞肌动蛋白纤维(F-actin)的分布.结果:乳杆菌黏附细胞后,单层细胞通透性并未见明显的变化,F-actin呈丝状或束状分布;乳杆菌与致病性大肠杆菌共孵育组细胞通透性略有增加,F-actin呈轻微点状分布.结论:乳杆菌黏附肠上皮细胞后,不影响细胞微丝骨架的分布,并且能够减弱由致病性大肠杆菌引起的单层肠上皮细胞的通透性增加和细胞微丝骨架的重排.     

表皮生长因子增强TPN减少放射性肠炎细菌易位及其机理的实验研究

腹部受辐射 ( abdominal rdiation,AR)致放射性肠炎常导致肠粘膜屏障损害和细菌易位。接受长期 TPN( total parenteral nutrition,TPN)改善营养的同时 ,可加重细菌易位 ,并导致多器官功能衰竭等致死性并发症。即使给予肠粘膜代谢所需的谷氨酰胺 ( Glutamine,Gln)亦不能完全防治其损伤。EGF( epidermal growth factor)是胃肠道粘膜上皮生长和增殖的介质。本研究在 SD大鼠放射性肠炎模型上观察了 EGF增强 TPN对放射性肠炎细菌易位及对损伤的肠粘膜修复的影响 ,结果发现 ,经 EGF增强的 TPN治疗大鼠放射性肠炎 ,大鼠死亡率、细菌易位率均较不用 TPN及应用不含 EGF的 TPN组明显下降 ,体重、粘膜 /肠段重量比、绒毛高度、面积、小肠 Gln摄取率及 DNA含量均明显升高。机理为 :EGF对小肠粘膜有明显的滋养作用。EGF增强 TPN在提供较完善营养及肠道充分休息 ,促进创伤愈合的同时 ,通过提高肠粘膜对 Gln的摄取能力 ,维持肠粘膜上皮的正常代谢 ,加速修复损伤的肠粘膜屏障 ,降低细菌易位率 ,从而降低死亡率     

Glutamine Supplementation Decreases Intestinal Permeability and Preserves Gut Mucosa Integrity in an Experimental Mouse Model

Background: Glutamine (GLN) is the preferred fuel for enterocytes, and GLN supplementation is critical during stressful conditions. The aim of this study was to evaluate the effect of GLN on intestinal barrier permeability and bacterial translocation in a murine experimental model. Methods: Swiss male mice (25–30 g) were randomized into 3 groups: (1) sham group; (2) intestinal obstruction (IO) group; (3) IO and GLN (500 mg/kg/d) group. Two different experiments were carried out to assess intestinal permeability and bacterial translocation. In the first experiment, the animals were divided into the 3 groups described above and received diethylenetriamine pentaacetate radiolabeled with technetium (^99mTc) on the eighth day. At different time points after intestinal obstruction, blood was collected to determine radioactivity. The animals were killed, and the small intestine was removed for histological analyses. In the bacterial translocation study, on the eighth day all groups received Escherichia coli labeled with ^99mTc. After 90 minutes, the animals underwent intestinal obstruction and were killed 18 hours later. Blood, mesenteric lymph nodes, liver, spleen, and lungs were removed to determine radioactivity. Statistical significance was considered when P ≤ .05. Results: The levels of intestinal permeability and bacterial translocation were higher in the IO group than in the sham and GLN groups (P < .05). GLN decreased intestinal permeability and bacterial translocation to physiologic levels in the treated animals and preserved intestinal barrier integrity. Conclusions: GLN had a positive impact on the intestinal barrier by reducing permeability and bacterial translocation to physiologic levels and preserving mucosal integrity.     

精氨酸增强全肠外营养对急性胰腺炎大鼠肠粘膜屏障的影响

目的：探讨精氨酸增强精氨酸增强ＴＰＮ对急性胰腺炎（ＡＰ）大鼠肠粘膜屏障的影响。方法：雄性ＳＤ大鼠６４只，随机分成：①对照组（ｎ＝１６）；②ＡＰ组（ｎ＝１６）；③ＡＰ＋ＴＰＮ组（ＴＰＮｓ组ｎ＝１６）；④ＡＰ＋ＴＰＮ＋精氨酸组（ＴＰＮａ组ｎ＝１６）。分别于建立急性胰腺炎模型后第１及第５天剖杀每组８只大鼠取材，检测肠粘膜一氧化氮（ＮＯ）、丙二醛、蛋白质含量、肠系膜淋巴结及门静脉血细菌移位率。结果：与对照组比较，术后１天及５天时，ＡＰ组肠粘膜丙二醛焦点量及肠系膜淋巴结细菌移位率显著升高；５天时蛋白质含量显著降低，而门静脉血细菌移位率明显升高。与ＴＰＮｓ组比较，ＴＰＮａ组１天时肠粘膜ＮＯ含量即明显升高；肠系膜淋巴结细胞移位率显著降低；５天时肠粘膜ＮＯ与蛋白质含量均显著升高；丙二醛含量显著降低。结论：急性胰腺炎可引起肠粘膜     

Effects of protein malnutrition and endotoxin on the intestinal mucosal barrier to the translocation of indigenous flora in mice

Since protein malnourished or endotoxemic patients are at increased risk of developing nosocomial infections with enteric organisms, we investigated the effects of these risk factors alone and in combination on the intestinal mucosal barrier to bacteria. Protein malnutrition resulted in severe ileal atrophy that was directly related to the length of time the mice were protein malnourished. Although protein malnutrition did not promote bacterial translocation from the gut to systemic organs, the protein-malnourished mice were more susceptible to endotoxin-induced bacterial translocation than normally nourished mice (p less than 0.01). Since the gross epithelial damage documented after endotoxin administration in normally nourished mice was diminished after protein malnutrition, there was no correlation between the gross appearance of the epithelial mucosal barrier and the extent of endotoxin-induced bacterial translocation. These results suggest that the synergistic effect of endotoxin plus protein malnutrition on bacterial translocation is not primarily related to failure of the gut mucosal barrier. Nonetheless, it appears that protein-malnourished mice are less able to clear translocating bacteria than normally nourished mice.