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。     

四君子汤及其纳米制剂对微生态失调小鼠的调整作用

目的研究四君子汤水提液及纳米制剂对肠道微生态失调小鼠的调整作用。方法应用林可霉素灌胃建立小鼠肠道微生态失调模型,然后应用四君子汤水提液(常态中药)及其纳米制剂进行治疗,同时设正常、阳性对照及自然恢复组,于给药6 d后处死小鼠,进行肠道菌群检测、肠组织电镜检查及肝脏细菌易位检测。结果林可霉素灌胃3 d后,小鼠肠道菌群失调,肠黏膜损伤严重,肝脏有大量细菌易位。持续6 d治疗后,肠道双歧杆菌和乳酸杆菌菌量明显上升,损伤的肠黏膜基本修复,肝脏细菌易位数量大幅度下降。各治疗组间比较纳米中药组的效果要好于常态中药和丽珠肠乐组(P<0.001,P<0.01,P<0.05)。结论2种不同粒径的中药均能扶植肠道正常菌群生长,促进肠黏膜损伤修复,控制细菌易位。但纳米中药效果优于常态中药,且用药量小。     

谷氨酰胺对急进高原大鼠肠道微生态影响的实验研究

目的探讨谷氨酰胺对急进高原大鼠小肠黏膜形态结构及肠道微生态的影响。方法W istar大鼠50只,随机分为5组:对照组(A组)、3848米未干预组(B组)、3848米谷氨酰胺干预组(C组)、4767米未干预组(D组)和4767米谷氨酰胺干预组(E组),每组10只,急进海拔3848米和4767米造成大鼠急性缺氧模型,检测小肠黏膜上皮细胞形态结构、肠道菌群失衡及细菌易位的变化。结果高海拔缺氧组大鼠小肠黏膜变薄、肠黏膜水肿、绒毛短缩,肠道菌群失衡显著高于对照组(P0.05),且随着海拔升高,菌群失衡更明显。不同海拔高度细菌易位率也有差异。经谷氨酰胺干预后,肠道的菌群失衡及细菌易位率与高海拔缺氧组比较差异有显著性(P0.05)。结论急进高原缺氧环境可导致小肠黏膜损伤、肠道菌群失衡及细菌易位,肠黏膜屏障破坏,且随着海拔升高而上述改变更明显。谷氨酰胺具有保护肠黏膜屏障及调节肠道菌群失衡的作用。     

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。     

肠道菌群影响黏膜屏障结构与功能的研究进展

肠道黏膜屏障具有防止致病性抗原侵入、维护肠道健康的功能。而肠道菌群是肠道黏膜屏障的重要构成部分,肠道菌群失调会导致肠道黏膜屏障的损伤,引起炎性肠病、肠易激综合征及肝、肾等多种疾病的发生发展。因此,本文从肠道黏膜的结构与功能及肠道菌群对其的影响等方面归纳总结肠道菌群对屏障系统的调控作用,从调节肠道微生态平衡、促进黏液分泌、影响紧密连接和肠道上皮通透性、激发肠黏膜免疫、调控肠上皮凋亡、影响肠上皮DNA稳定性及产生特殊代谢产物等方面阐述其作用机制,为临床胃肠道疾病及其并发症的治疗提供新的思路和方法。     

SD大鼠断奶后肠道菌群及肠道形态的变化

目的通过对断奶日龄不同的SD大鼠肠道菌群和肠道形态学指标变化的观察研究,为临床上研究肠道相关性疾病提供参考数据。方法选取断奶日龄为21 d的SD大鼠60只,雌雄各半,分别在断奶后第0、7、14、21、28天测定4种肠道正常菌群及肠道黏膜形态变化。结果SD大鼠断奶后不同时间点,不同肠段内大肠杆菌、双歧杆菌、乳酸杆菌和葡萄球菌呈现不同的变化规律,且断奶后第7天肠道细菌移位率明显提高,同时断奶后不同时间点,大鼠不同肠段黏膜厚度、肌层厚度、绒毛长度和宽度都呈现上升趋势。结论断奶后第7天和14天,SD大鼠肠道菌群和肠道形态学变化明显,且易发生肠道细菌移位。     

抗生素对小鼠菌群失调腹泻肠道菌群多样性的影响

目的探讨菌群失调腹泻抗生素造模对小鼠肠道菌群多样性的影响,为临床用药提供依据。方法运用混合抗生素建立小鼠菌群失调腹泻模型,采集肠道内容物,提取肠道微生物宏基因组,通过特定引物PCR扩增后进行扩增核糖体DNA限制性分析(Amplified rDNA Restriction Analysis,ARDRA)探讨其多样性的变化。结果正常组和模型组细菌的OTUs数为6、5,乳酸杆菌的OTUs数为6、4;模型组细菌和乳酸杆菌的多样性同正常组比较分别为59.91%、40.00%。结论抗生素造模使得肠道内的微生态平衡被破坏,肠道菌群多样性下降。     

马齿苋多糖对肠道微生态失调小鼠的调整作用研究

目的研究应用马齿苋多糖对肠道微生态失调小鼠进行调整治疗,达到从微生态学角度防治感染的目的。方法应用林可霉素灌胃建立肠道微生态失调小鼠模型,然后用马齿苋多糖进行治疗,同时设正常对照组、阳性对照组和阴性对照组,于给药7 d后处死小鼠,进行肠道菌群定量、肠内容物挥发性脂肪酸检测及肠黏膜电镜观察。结果林可霉素灌胃3 d后,小鼠肠道菌群失调,肠内容物挥发性脂肪酸含量明显下降,肠黏膜损伤严重。持续7 d治疗后,治疗组小鼠肠道双歧杆菌和乳酸杆菌数量明显上升,肠内容物挥发性脂肪酸含量明显上升,损伤的肠黏膜基本修复。结论应用林可霉素可以成功建立肠道微生态失调动物模型;马齿苋多糖具有扶植肠道正常菌群生长,调整菌群失调,防治感染的作用,是理想的中药微生态调节剂。     

西藏灵菇奶对抗生素相关性腹泻小鼠肠道菌群的调整作用

目的研究用西藏灵菇对抗生素引起的肠道菌群失调及病理变化的调整作用.方法由林可霉素造成小鼠腹泻模型,并证实肠道菌群紊乱后,将其分成灵菇奶治疗组和自然恢复组,7 d后对每个组小鼠进行肠道菌群检测,同时取回肠末段组织标本用光镜及电镜观察黏膜结构的变化.结果抗生素模型组大多数小鼠肠道黏膜出现不同程度的损害,小鼠肠道的正常菌群及病理组织改变基本恢复正常.结论灵菇奶不仅对肠道菌群有调整作用,而且对肠黏膜的修复有一定作用.     

肝硬化患者肠道菌群失衡的研究现状

肝硬化是我国的一种常见病,近年来越来越多的研究表明肝硬化及其并发症(如门静脉高压、自发性腹膜炎、肝性脑病及肝癌等)都与肠道菌群失衡有着密切的联系。肝脏和肠道通过"肠-肝轴"紧密联系在一起,肝硬化时因小肠细菌过度生长、肠黏膜屏障功能受损、机体免疫功能下降等因素,导致细菌移位、肠道微生态失衡。而肠道微生态失衡又会使肝功能障碍进一步发展,引起肝性脑病等并发症。本文就目前国内外对肝硬化及其并发症与肠道细菌及真菌菌群失衡的研究进行综述。     

大承气汤对MODS时肠道细菌微生态学影响的实验研究

目的探讨多器官功能不全综合征(MODS)大鼠肠道细菌微生态的变化及其与肠源性内毒素血症和细菌易位的关系,并观察大承气汤的影响。方法32只SD大鼠随机分成4组,对照组、模型组、大承气组和氨苄青霉素组。腹腔注射无菌酵母多糖A制备大鼠MODS模型。各组动物于造模后48 h无菌操作抽取外周静脉血和门静脉血进行内毒素含量测定;取肠系膜淋巴结进行细菌定量培养,取回肠和盲肠内容物进行肠腔内游离内毒素测定;取盲肠内容物进行肠道细菌微生态学分析。结果模型组外周血和门静脉血内毒素水平以及肠腔内游离内毒素含量均明显高于对照组(P<0.05);与对照组相比,模型组肠道菌群出现明显变化。肠球菌、肠杆菌数量明显增加,而双歧杆菌和乳酸杆菌数量出现显著下降,类杆菌数量亦出现明显下降(P<0.05)。模型组厌氧菌总数明显下降而需氧菌总数明显增加,同时厌氧菌总数/需氧菌总数的比值和B/E比值呈相应下降,发生倒置(P<0.05);正常对照组未发现肠道细菌向肠系膜淋巴结的易位,而模型组细菌易位阳性率是83.33%(P<0.05)。与模型组相比,大承气汤组上述各指标均出现明显变化(P<0.05);抗生素组作用不明显(P>0.05)。结论MODS时大鼠肠道细菌微生态出现明显变化,发生肠源性内毒素血症和细菌易位。大承气汤可以调整肠道菌群,恢复肠道微生态平衡,增加机体定植抗力,防治细菌易位和内毒素血症。     

Outside the liver box: The gut microbiota as pivotal modulator of liver diseases

The gut microbiota affects host physiology and has evolved as an important contributor to health and disease. Gut and liver are closely connected and communicate via the portal vein and the biliary system so the liver is constantly exposed to gut-derived bacterial products and metabolites. The intestinal barrier is important for maintaining physical and functional separation between microbes in the gut and the interior of the host and disruption of the barrier function can lead to bacterial translocation and increased leakage of bacterial metabolites. Liver diseases have been associated with dysbiotic changes in the gut microbiota and impaired gut barrier integrity, thus a future strategy to treat liver disease may be to target the gut microbiota and thereby restore the gut barrier function. This review will summarize and discuss studies that have shown a link between the gut microbiota and liver disease with the main focus on non-alcoholic fatty liver disease and alcoholic liver disease.     

Gut-associated lymphoid T cell suppression enhances bacterial translocation in alcohol and burn injury

The mechanism of alcohol-mediated increased infection in burn patients remains unknown. With the use of a rat model of acute alcohol and burn injury, the present study ascertained whether acute alcohol exposure before thermal injury enhances gut bacterial translocation. On day 2 postinjury, we found a severalfold increase in gut bacterial translocation in rats receiving both alcohol and burn injury compared with the animals receiving either injury alone. Whereas there were no demonstrable changes in intestinal morphology in any group of animals, a significant increase in intestinal permeability was observed in ethanol- and burn-injured rats compared with the rats receiving either injury alone. We further examined the role of intestinal immune defense by determining the gut-associated lymphoid (Peyer's patches and mesenteric lymph nodes) T cell effector responses 2 days after alcohol and burn injury. Although there was a decrease in the proliferation and interferon-gamma by gut lymphoid T cells after burn injury alone; the suppression was maximum in the group of rats receiving both alcohol and burn injuries. Furthermore, the depletion of CD3(+) cells in healthy rats resulted in bacterial accumulation in mesenteric lymph nodes; such CD3(+) cell depletion in alcohol- and burn-injured rats furthered the spread of bacteria to spleen and circulation. In conclusion, our data suggest that the increased intestinal permeability and a suppression of intestinal immune defense in rats receiving alcohol and burn injury may cause an increase in bacterial translocation and their spread to extraintestinal sites.     

肠道屏障损伤及细菌移位在焦虑抑郁症诱导退行性神经症中的机制

肠道屏障是脑-肠道交互作用的晴雨表。健全的肠道屏障对于维系肠道内微生态,抵御外源性病原体的侵入至关重要。焦虑抑郁症能够损害肠道屏障,破坏肠道菌群平衡。肠道屏障损伤引起肠道渗透性升高,肠腔细菌移位,促使外源性病原体进入血液循环和神经系统,启动系统性炎症反应。炎症反应对脑神经的损伤是诱导阿尔茨海默病和帕金森症发生、发展的主要原因。肠道屏障损伤还会破坏原有的肠道菌群结构,造成肠道菌群失调,不仅进一步损伤肠道屏障,还影响神经组织的结构和功能,是阿尔茨海默病和帕金森症形成的另一因素。此综述依据近年来的相关研究,从肠道屏障损伤的角度阐述了焦虑抑郁症触发退行性神经症的机制,强调维护肠道屏障功能在预防退行性神经疾病中具有重要的临床意义。     

Oral Supplementation with Non-Absorbable Antibiotics or Curcumin Attenuates Western Diet-Induced Atherosclerosis and Glucose Intolerance in LDLR?/? Mice – Role of Intestinal Permeability and Macrophage Activation

Association between circulating lipopolysaccharide (LPS) and metabolic diseases (such as Type 2 Diabetes and atherosclerosis) has shifted the focus from Western diet-induced changes in gut microbiota per se to release of gut bacteria-derived products into circulation as the possible mechanism for the chronic inflammatory state underlying the development of these diseases. Under physiological conditions, an intact intestinal barrier prevents this release of LPS underscoring the importance of examining and modulating the direct effects of Western diet on intestinal barrier function. In the present study we evaluated two strategies, namely selective gut decontamination and supplementation with oral curcumin, to modulate Western-diet (WD) induced changes in intestinal barrier function and subsequent development of glucose intolerance and atherosclerosis. LDLR−/− mice were fed WD for 16 weeks and either received non-absorbable antibiotics (Neomycin and polymyxin) in drinking water for selective gut decontamination or gavaged daily with curcumin. WD significantly increased intestinal permeability as assessed by in vivo translocation of FITC-dextran and plasma LPS levels. Selective gut decontamination and supplementation with curcumin significantly attenuated the WD-induced increase in plasma LPS levels (3.32 vs 1.90 or 1.51 EU/ml, respectively) and improved intestinal barrier function at multiple levels (restoring intestinal alkaline phosphatase activity and expression of tight junction proteins, ZO-1 and Claudin-1). Consequently, both these interventions significantly reduced WD-induced glucose intolerance and atherosclerosis in LDLR−/− mice. Activation of macrophages by low levels of LPS (50 ng/ml) and its exacerbation by fatty acids is likely the mechanism by which release of trace amounts of LPS into circulation due to disruption of intestinal barrier function induces the development of these diseases. These studies not only establish the important role of intestinal barrier function, but also identify oral supplementation with curcumin as a potential therapeutic strategy to improve intestinal barrier function and prevent the development of metabolic diseases.     

Inadequate Clearance of Translocated Bacterial Products in HIV-Infected Humanized Mice

Bacterial translocation from the gut and subsequent immune activation are hallmarks of HIV infection and are thought to determine disease progression. Intestinal barrier integrity is impaired early in acute retroviral infection, but levels of plasma lipopolysaccharide (LPS), a marker of bacterial translocation, increase only later. We examined humanized mice infected with HIV to determine if disruption of the intestinal barrier alone is responsible for elevated levels of LPS and if bacterial translocation increases immune activation. Treating uninfected mice with dextran sodium sulfate (DSS) induced bacterial translocation, but did not result in elevated plasma LPS levels. DSS-induced translocation provoked LPS elevation only when phagocytic cells were depleted with clodronate liposomes (clodrolip). Macrophages of DSS-treated, HIV-negative mice phagocytosed more LPS ex vivo than those of control mice. In HIV-infected mice, however, LPS phagocytosis was insufficient to clear the translocated LPS. These conditions allowed higher levels of plasma LPS and CD8+ cell activation, which were associated with lower CD4+/CD8+ cell ratios and higher viral loads. LPS levels reflect both intestinal barrier and LPS clearance. Macrophages are essential in controlling systemic bacterial translocation, and this function might be hindered in chronic HIV infection.     

Ultrastructural study on route of gut bacterial translocation in a rat after spinal cord injury

Objective: To observe the ultrastructural change of the route of gut bacterial translocation in a rat with spinal cord injury(SCI).Methods: Forty Wistar rats were divided into the following groups: control group and 3 SCI groups(10 in each group). The rats in the SCI groups were established SCI model at 24 h, 48 h, and 72 h after SCI. Small intestine mucous membrane tissue was identified and assayed by transmission electron microscope, scanning electron microscope and immunofluorescence microscopy. Results: Small intestine mucous membrane tissue in control group was not damaged significantly, but those in SCI groups were damaged significantly. Proliferation bacteria in gut lumen attached on microvilli. The extracellular bacteria torn the intestinal barrier and perforated into the small intestinal mucosal epithelial cell. The bacteria and a lot of particles of the seriously damaged region penetrated into the lymphatic system and the blood system directly. Some bacteria were internalized into the goblet cell through the apical granule. Some bacteria and particles perforated into the submucosa of the M cell running the long axis of M cells through the tight junctions. In the microcirculation of mucosa, the bacteria that had already broken through the microvilli into blood circulation swim accompanying with erythrocytes. Conclusion: The routes of bacterial translocation interact and format a vicious circle. At early step, the transcellular pathway of bacterial translocation is major. Following with the destroyed small intestine mucous, the routes of bacterial translocation through the lymphatic system and the blood system become direct pathways. The goblet cell-dendritic cell and M cell pathway also play an important role in the bacterial translocation.