多联益生菌对5-氟尿嘧啶诱发大鼠肠道菌群紊乱及肠黏膜损伤的保护作用

目的研究多联益生菌对5-氟尿嘧啶(5-Fu)诱发大鼠肠道菌群紊乱、肠黏膜损伤以及脾脏损伤的保护作用。方法 28只SPF级SD大鼠随机分为正常组、5-Fu+生理盐水组、5-Fu+低剂量益生菌组和5-Fu+高剂量益生菌组,每组7只。所有大鼠于化疗结束后第3天处死,应用PCR-DGGE技术测定肠道菌群变化,鲎试剂测定血浆内毒素含量,HE染色观察肠黏膜变化和脾脏变化。结果与5-Fu+生理盐水组相比,经益生菌干预后的大鼠其肠道菌群失调和体重减轻症状有明显改善,血浆内毒素含量显著降低,肠黏膜损伤也得到了显著改善,脾脏淋巴细胞明显增多,脾脏损伤程度降低。结论该多联益生菌制剂能有效减轻5-Fu对大鼠肠黏膜及肠道菌群的破坏,同时减轻其对脾脏的损伤,并且改善大鼠在化疗后的生存质量。     

骶神经电刺激对脊髓损伤大鼠肠黏膜机械屏障的保护作用

目的：观察骶神经电刺激对脊髓损伤大鼠肠黏膜机械屏障的保护作用。方法：56只Wistar大鼠分7组（n=8）：正常组、急性完全性脊髓损伤（SCI）组和骶神经电刺激组（按24、48、72h各8只）。进行内毒素测定;肠系膜淋巴结、肝脏、脾脏菌培养;肠道形态学观察;紧密连接蛋白zo-1的蛋白表达测定。结果：对照组肠黏膜不同程度损伤;肠道上皮细胞及细胞间连接破坏;内毒素血症和细菌移位明显。实验组肠黏膜得到改善,内毒素水平下降且细菌移位减少。ZO-1蛋白表达无统计学差异。对照组ZO-1的分布出现不同程度的散乱、排列不规则,实验组分布得到改善。结论：骶神经电刺激可促肠蠕动、排肠内容物、减少肠道菌群数量,保护肠黏膜上皮细胞及紧密连接的机械屏障,减少细菌移位和内毒素血症。     

化疗对肠道菌群及血清5-羟色胺水平的影响

化疗不仅导致肠黏膜炎和5-羟色胺(5-HT)水平的异常,也会诱发肠道菌群失衡。平衡状态下的微生物是一道生物屏障,菌群失衡可加剧肠道炎症。近期研究发现,5-HT的水平受肠道菌群的调节。因此,化疗引起的5-HT水平改变可能与肠道菌群的异常有关。本研究主要探讨肠道菌群通过何种途径影响化疗后肠黏膜炎和5-HT水平,为临床上以益生菌调节肠道菌群来改善化疗后的胃肠道反应提供依据。     

抗生素所致腹泻大鼠肠屏障功能损伤及乳酸杆菌保护机制的研究

目的探讨抗生素对所致腹泻大鼠肠道屏障功能、肠道菌群结构和肠道细菌移位的影响及乳酸杆菌制剂的保护机制。方法采用细菌培养法动态测定抗生素所致腹泻大鼠肠道菌群变化及肠系膜淋巴结、肝脏、脾脏和结肠组织的移位细菌量;应用光镜和电子显微镜观察肠黏膜组织超微结构变化。结果应用抗生素可致大鼠腹泻,肠道菌群失调,肠黏膜组织受损,发生肠道细菌移位。大肠埃希菌攻击可加重肠道菌群失调和肠黏膜损伤程度,促发细菌移位发生。乳酸杆菌可扶正肠菌群结构,修复损伤的肠黏膜,抑制肠细菌移位发生。结论阐明了抗生素、肠黏膜屏障功能、肠道菌群结构和肠道细菌移位间的互为因果,相互影响的关系。微生态制剂在维持机体微生态平衡、修复肠黏膜方面具有保护作用。     

红花多糖对肠道微生态失调小鼠肠黏膜sIgA、血浆内毒素和肠道菌群的影响

目的 研究红花多糖对肠道微生态失调小鼠的调节作用,探讨红花多糖改善微生态失调与肠黏膜免疫、血浆内毒素及肠道菌群的关系.方法 应用盐酸林可霉素灌胃建立肠道微生态失调小鼠模型,然后用红花多糖进行治疗,同时设正常对照组(n=5)、自然恢复组(n=5)和丽珠肠乐组(n=5).于给药7d后处死小鼠,进行肠黏膜sIgA、血浆内毒素...     

布拉氏酵母菌对肝硬化模型大鼠的影响

目的研究布拉氏酵母菌能否通过改善肠源性内毒素血症、肠道环境改善四氯化碳诱导的肝硬化模型大鼠肝纤维化的程度。方法50只雄性Wistar大鼠随机分为正常组（8只）、模型组（20只）、预防组（14只）和治疗组（8只）。预防组在制模同时给予喂服布拉氏酵母菌制剂,治疗组在制模成功后开始给予喂服布拉氏酵母菌制剂,正常组和模型组给予同等生理盐水喂服。实验过程中每周称量所有大鼠体重,观察其日常生活习性,实验在18周末处死所有大鼠,HE染色观察肝脏病理改变,测定血清中天冬氨酸转氨酶（AST）、丙氨酸转氨酶（ALT）、丙二醛（MDA）和白蛋白（ALB）水平及血浆内毒素含量,用变性梯度凝胶电泳法检测大鼠肠道菌群情况。结果正常组[（0．052±0．005）EU／mL]、预防组[（0．058±0．028）EU／mL]和治疗组[（0．230±0．027）EU／mL]大鼠血浆中的内毒素明显低于模型组[（0．310±0．039）EU／mL]（P〈0．05）。预防组和正常组大鼠血浆内毒素含量有区别,但差异无统计学意义。通过变性梯度凝胶电泳发现正常组大鼠肠道菌群数量明显好于模型组,肝硬化大鼠肠道菌群失衡。而治疗组介于预防组和模型组之间。结论布拉氏酵母菌对于改善肝硬化模型大鼠肠道菌群情况,减少肠源性内毒素血症有重要意义。     

抗生素对新生大鼠肠道免疫发育影响及双歧杆菌干预的研究

目的 研究新生大鼠口服抗生素对肠道免疫发育的影响及双歧杆菌干预的效果.方法 选用50只7日龄新生SD大鼠,每组10只,随机分为5组:对照组(A)、抗生素组(B)、益生菌组(C)、益生菌干预组(D)和生理盐水组(E).A组为空白对照,B组给予头孢克洛灌胃,C组给予双歧杆菌灌胃,D组先给头孢克洛灌胃,2h后再灌长双歧杆菌,E组每天灌以等量的生理盐水,持续2周后处死大鼠,取少许新鲜盲肠内容物粪便涂片,免疫组化方法检测末端回肠肠组织中CD4、CD8的表达和组织学观察.结果 粪便涂片结果显示:B组与其余四组相比G+b占肠道总细菌数比率明显下降,G-b及G+c占总细菌数比率明显升高(P＜0.01).组织形态学观察:C组与E组肠黏膜绒毛和腺体发育良好,上皮结构完整,排列整齐,而A组腺体发育少,绒毛高度小;B组肠黏膜绒毛和腺体萎缩,黏膜水肿,部分上皮细胞变性、坏死、脱落;D组肠黏膜绒毛和腺体排列整齐绒毛显示清楚,少部分黏膜上皮细胞脱落、坏死.组肠组织中CD4、CD8的表达:B组CD4、CD8表达程度受到抑制,灰度值增大(P＜0.05);C组与E组相比CD4、CD8表达增加,灰度值比较差异有统计学意义(P＜0.05).结论 肠道菌群的正常定植,刺激肠道免疫系统的发育.新生大鼠口服抗生素后肠黏膜结构被破坏以及干扰肠道菌群的定植,影响肠道免疫系统的发育.长双歧杆菌的能预防抗生素引起的菌群紊乱,维持肠道黏膜的完整性,保护肠道免疫系统的正常发育.     

创伤后血二胺氧化酶的变化与肠粘膜损伤

探讨创伤感染对肠道屏障功能的影响。以山羊、大鼠手术+失血再灌注+内毒素(LPS),大鼠肠缺血再灌注和犬低温枪伤多种创伤动物为模型,测定血浆二胺氧化酶(DAO)活性,并测定血乳酶、TNF和LPS含量。观察小肠病理形态改变。结果:失血再灌注后血浆DAO水平显著升高,给予内毒素后山羊血DAO水平再度升高。血浆DAO的变化与血乳酸,TNF和LPS变化呈高度相关(r=0.872,0.842和0.817,p<0.01)。光、电镜检查表明肠粘膜损伤,失血再灌注损伤可致肠粘膜屏障功能损伤,测定血浆DAO活性变化对判断小肠粘膜损伤有帮助     

益生菌对烧伤大鼠肠道膜菌群和sIgA的影响

目的探索益生菌对严重烧伤大鼠早期肠道菌群的调理作用,为防治肠源性感染寻找新途径.方法选用健康Wistar大鼠100只,体重180～220 g,雌雄各半,随机分为:益生菌治疗组(BR),烧伤对照组(BC)和正常对照组(NC),建立30% Ⅲ°烫伤肠源性感染的动物模型,按时分批活杀取材,检测盲肠膜菌群和肠黏膜sIgA的含量.结果 BC组盲肠中双歧杆菌数量与NC组比较,明显减少(P＜0.01),而BR组与NC组比较,差异无显著性(P＞0.05);BC组肠道中酵母菌和大肠埃希菌与NC比较明显增加,BR组差异无显著性;肠粘液sIgA水平与上述指标有类似变化.结论 30%Ⅲ°烫伤大鼠肠道内容物中,双歧杆菌明显下降,大肠埃希菌、酵母菌迅速过生长,导致肠道微生态失衡,应用BR治疗后,促进肠黏膜机械屏障功能的恢复,调理肠道微生态平衡,对肠黏膜起占位性保护作用,提高了肠道局部和全身益生菌免疫的功能.     

乳酸杆菌制剂对应用抗生素大鼠体内TLR2 mRNA转录水平及相关因素影响的研究

目的动态观察乳酸杆菌制剂对应用抗生素大鼠肠道菌群结构和TLR2 mRNA转录水平的影响。方法采用细菌培养法定量检测肠道双歧杆菌、乳酸杆菌、肠杆菌和肠球菌;利用反转录聚合酶链反应技术测定大鼠肠黏膜组织、肠系膜淋巴结、肝脏和脾脏细胞TLR2 mRNA转录水平。结果应用抗生素可致肠道菌群失调和TLR2 mRNA转录水平的早期受抑制。乳酸杆菌制剂干预可迅速提高肠道乳酸杆菌数量,及早扶正肠道菌群结构,减轻由于应用抗生素引起的Toll样受体mRNA转录受抑程度。结论乳酸杆菌制剂早期干预可及早扶正肠道菌群结构,减轻TLR2 mRNA转录水平受抑制程度,为临床合理应用抗生素,早期益生菌干预提供理论依据。     

Interaction of vasoactive intestinal peptide with rat small intestinal epithelial cells after intestinal resection

Specific binding of vasoactive intestinal peptide (VIP) and VIP-stimulated c y c l i c AMP accumulation were studied in small intestinal epithelial cells (both of crypt and villous levels) 3, 7 and 14 d after a 60% resection of the small intestine . The affinity, but not the binding capacity, of VIP receptors decreased during the adaptive hyperplastic response. Basal cyclic AMP levels were similar in cells of both control and resected rats. Resection induced a decrease of potency, but not of efficiency, of VIP on the stimulation of cyclic AMP accumulation.     

肠黏膜屏障与肠道菌群的相互关系

摘要：人类肠道中微生物群与肠道环境相互作用以维持机体健康。肠黏膜屏障主要由黏液层、肠道菌群、肠道免疫系统和肠上皮细胞本身的完整性等构成。肠道作为直接与大量菌群接触的器官,其屏障功能在肠道健康中的作用尤为显著。肠道菌群与肠道屏障相互作用,保持肠道菌群与肠道屏障相对稳定,肠道菌群参与肠道免疫反应的建立,共同建立机体天然防御系统,在保持肠道免疫的动态平衡中具有重要作用。当两者之间的平衡被打破时,可诱发功能性胃肠病（如肠易激综合征）及免疫相关性疾病（如炎症性肠病）。本文主要阐述肠黏膜屏障与肠道菌群之间的相互关系以及与肠道屏障功能障碍相关的肠道疾病。     

Effect of intestinal ischaemia on intestinal VIP levels and VIP interaction with intestinal epithelial cells from rat

1. The number (but not the affinity) of vasoactive intestinal peptide (VIP) receptors in small intestinal epithelial cells decreased following intestinal ischaemia in rats as compared to sham-operated animals. 2. There was a parallel decrease of the efficiency (but not the potency) of the neuropeptide upon cyclic AMP formation at the same level after intestinal ischaemia. 3. The surgical manipulation did not modify the level of VIP immunoreactivity in the gut segment studied. 4. These results suggest that the VIPergic system is not directly involved in the high loss of water and electrolytes that appears following intestinal ischaemia.     

肠道微生物对肠道屏障功能完整性的维护机制研究概况

肠道微生物群是一个稳定且复杂的生态系统,可以通过形成菌膜屏障或促进肠道上皮细胞增殖分化等方式形成保护屏障,并在肠道病原菌感染和威胁期间维持和促进免疫稳态中起积极作用。本文重点叙述宿主-肠道微生物相互作用过程中抗病原菌感染的方式,以及肠道微生物参与合成抗菌化合物抵御肠道病原菌入侵和威胁的机制,为调控肠道微生物解决临床胃肠道疾病及其相关症状提供理论参考依据。     

Neuropeptide neurotensin stimulates intestinal wound healing following chronic intestinal inflammation

Because neurotensin (NT) and its high-affinity receptor (NTR1) modulate immune responses, chloride secretion, and epithelial cell proliferation, we sought to investigate their role in the repair process that follows the development of mucosal injuries during a persistent inflammation. Colonic NT and NTR1, mRNA, and protein significantly increased only after dextran sodium sulfate (DSS)-induced inflammatory damage developed. Colitis-induced body weight loss, colonic myeloperoxidase activity, and histological damage were significantly enhanced by SR-48642 administration, a nonpeptide NTR1 antagonist, whereas continuous NT infusion ameliorated colitis outcome. To evaluate the NT and NTR1 role in tissue healing, mucosal inflammatory injury was established administering 3% DSS for 5 days. After DSS discontinuation, mice rapidly gained weight, ulcers were healed, and colonic NT, NTR1, and cyclooxygenase (COX)-2 mRNA levels were upregulated, whereas SR-48642 treatment caused a further body weight loss, ulcer enlargement, and a blunted colonic COX-2 mRNA upregulation. In a wound-healing model in vitro, NT-induced cell migration in the denuded area was inhibited by indomethacin but not by an antitransforming growth factor-beta neutralizing antibody. Furthermore, NT significantly increased COX-2 mRNA levels by 2.4-fold and stimulated PGE(2) release in HT-29 cells. These findings suggest that NT and NTR1 are part of the network activated after mucosal injuries and that NT stimulates epithelial restitution at least, in part, through a COX-2 dependent pathway.     

Relationship between intestinal microecology and the translocation of intestinal bacteria

It is now well known that endogenous bacteria can translocate from the intestinal tract and cause many of the complicating infections seen in severely ill, hospitalized patients. Of the hundreds of bacterial species in the intestinal tract, relatively few aerobic/facultative species appear to translocate with any frequency. Van der Waaij and colleagues (1971, 1972a, 1972b) originally proposed that, by a process termed colonization resistance, strictly anaerobic bacteria prevented the intestinal overgrowth and subsequent translocation of these potentially pathogenic aerobic/facultative bacteria. Selective antimicrobial decontamination, designed to maintain colonization resistance, has been effective in reducing the incidence of infectious morbidity in high risk patients. However, the mechanisms controlling bacterial translocation remain unclear, but appear to depend on host factors, as well as on factors inherent in the microbe itself. There is both clinical and experimental evidence supporting the concept that strictly anaerobic bacteria do not readily translocate. Bacteria that are able to survive within macrophages (e.g., Salmonella species and Listeria monocytogenes) translocate easier than others, and there is recent experimental evidence that normal intestinal bacteria may translocate to the draining mesenteric lymph node within host phagocytes. There is also evidence that anaerobic bacteria translocate along with facultative species in situations associated with intestinal epithelial damage, i.e., burn trauma, oral ricinoleic acid, and acute mesenteric ischemia. In contrast, recent experimental evidence demonstrates that facultative bacteria can translocate across a histologically intact intestinal epithelium, and that the ileal absorptive cell may be at least one portal of entry prior to transport into deeper tissues. It is anticipated that further clarification of the routes and mechanisms involved in bacterial translocation will provide new insights into the treatment and prevention of a significant proportion of the infectious morbidity seen in severely ill, hospitalized patients. Antoni van Leeuwenhoek Lecture presented at the Annual Meeting of the Netherlands Society of Microbiology, Utrecht, 23 November, 1989.     

Murine intestinal organoids resemble intestinal epithelium in their microRNA profiles

Intestinal organoids were established as an ex vivo model of the intestinal epithelium. We investigated whether organoids resemble the intestinal epithelium in their microRNA (miRNA) profiles. Total RNA samples were obtained from crypt and villus fractions in murine intestine and from cultured organoids. Microarray analysis showed that organoids largely resembled intestinal epithelial cells in their miRNA profiles. In silico prediction followed by qRT-PCR suggested that six genes are regulated by corresponding miRNAs along the crypt-villus axis, suggesting miRNA regulation of epithelial cell renewal in the intestine. However, such expression patterns of miRNAs and their target mRNAs were not reproduced during organoids maturation. This might be due to lack of luminal factors and endocrine, nervous, and immune systems in organoids and different cell populations between in vivo epithelium and organoids. Nevertheless, we propose that intestinal organoids provide a useful in vitro model to investigate miRNA expression in intestinal epithelial cells.