肠黏膜细胞的紧密连接与肠壁通透性的研究进展

肠黏膜细胞的紧密连接是构成肠黏膜屏障的重要结构基础,在调节肠黏膜通透性中发挥着重要的作用.其结构的破坏,可导致肠壁通透性增高,引起细菌移位、全身炎症反应及多器官功能受损.本文就肠黏膜紧密连接的结构和功能、与通透性的影响因素及改善措施进行了综述.     

肠道通透性研究进展

肠道通透性异常的现象在很多人类疾病中都存在,特别是在一些自身免疫性疾病中,肠道通透性的增加被认为与疾病的发病机制相关.因此,目前肠道通透性改变和疾病发病的关系受到关注.此文从肠道上皮屏障的结构、肠道通透性的检测方法及当前临床疾病相关的研究现状进行阐述.     

非侵入性方法检测肠黏膜屏障功能的研究进展

异常的肠道通透性在人类多种疾病中起着非常重要的作用,包括糖尿病、炎症性肠病、乳糜泻、多发性硬化、食物变态反应过敏症、肠易激综合征等.近年大量的研究发现:一些自身免疫性疾病伴有肠道通透性增加,这种现象发生在疾病之前,被认为与疾病的发病机制相关.研究肠黏膜屏障的功能与结构,可以提高我们对疾病的病因及病理生理认识,并且对于早期检测疾病以及对疾病进行二级预防有重要意义.目前有多种试验方法评估肠黏膜上皮细胞受损、紧密连接功能以及肠黏膜屏障的完整性.本篇综述主要探讨目前评估肠黏膜屏障功能的检测方法.     

Pathophysiology of increased intestinal permeability in obstructive jaundice

Despite advances in preoperative evaluation and postoperative care, intervention, especially surgery, for relief of obstructive jaundice still carries high morbidity and mortality rates, mainly due to sepsis and renal dysfunction. The key event in the pathophysiology of obstructive jaundice-associated complications is endotoxemia of gut origin because of intestinal barrier failure. This breakage of the gut barrier in obstructive jaundice is multi-factorial, involving disruption of the immunologic, biological and mechanical barrier. Experimental and clinical studies have shown that obstructive jaundice results in increased intestinal permeability. The mechanisms implicated in this phenomenon remain unresolved, but growing research interest during the last decade has shed light in our knowledge in the field. This review summarizes the current concepts in the pathophysiology of obstructive jaundice-induced gut barrier dysfunction, analyzing pivotal factors, such as altered intestinal tight junctions expression, oxidative stress and imbalance of enterocyte proliferation and apoptosis. Clinicians handling patients with obstructive jaundice should not neglect protecting the intestinal barrier function before, during and after intervention for the relief of this condition, which may improve their patients’ outcome.     

Effect of Rebamipide on the Colonic Barrier in Interleukin-10-Deficient Mice

Our aim was to study the effect of a mucosal protective agent, rebamipide, on the colonic barrier and the immune response in colitis-prone interleukin-10-deficient (IL-10−/−) C57BL/6 mice infected with Helicobacter hepaticus. After sacrifice, in all mice, control, or previously infected with H. hepaticus, or previously infected and treated with rebamipide enema, a histological examination of colonic samples was performed, intestinal permeability was studied in Ussing chamber, and mesenteric lymph node proliferation and cytokine secretion were measured. Mice treated with rebamipide presented a reinforcement of the distal colonic epithelial barrier, an increase of mesenteric lymph node cells proliferation, and of IFNγ and IL-12 secretion. These results indicate that in IL-10−/− mice with mild colitis, rectally administered rebamipide reinforces the distal colonic barrier and has a slight Th1 immuno-stimulatory effect on mesenteric lymph node cells. These properties could be helpful in the management of some inflammatory bowel diseases.     

Poly I:C对结肠炎小鼠肠黏膜通透性的影响

目的探索Poly I:C对结肠炎模型小鼠肠黏膜通透性的影响。方法 30只小鼠随机分为正常组、模型组和Poly I:C组各10只,建立结肠炎小鼠模型;观察各组的一般情况、体质量变化及结肠病理学表现,应用偶氮基质显色法测定血清脂多糖(LPS)含量,采用异硫氰酸荧光素标记的右旋葡聚糖(FITC-D,MW:4000)及细菌移位方法来检测肠黏膜通透性,免疫组织化学染色测定结肠组织中紧密连接蛋白ZO-1、claudin-1的变化。结果实验期间,与正常组相比较,模型组小鼠体质量出现下降,饮水和进食明显减少且结肠黏膜缺损,腺体破坏或消失,可见黏膜、黏膜下层甚至肌层大量炎性细胞浸润;给予Poly I:C治疗后,小鼠的体质量回升明显,且结肠组织炎性细胞浸润较少,症状明显减轻。相较于模型组,Poly I:C组血清中LPS的含量、细菌移位率及FITC-D渗透率均降低。相较于正常组,ZO-1、claudin-1细胞在模型组中表达明显降低且染色强度减弱。但给予Poly I:C治疗后,ZO-1和claudin-1细胞的染色强度显著升高。结论 Poly I:C可降低急性期溃疡性结肠炎模型小鼠结肠黏膜的通透性。     

Preventive Effects of Rebamipide on NSAID-Induced Gastric Mucosal Injury and Reduction of Gastric Mucosal Blood Flow in Healthy Volunteers

The precise mechanisms of acute damage and the role of gastric mucosal blood flow in gastric mucosal injury induced by nonsteroidal anti-inflammatory drugs (NSAIDs) remain uncertain. The aim of this study was to evaluate the preventive effect of rebamipide on gastric mucosal injury and reduction of gastric mucosal blood flow (GMBF) after ibuprofen administration. Twenty healthy volunteers were randomized two groups. The rebamipide group took ibuprofen, 1800 mg/day, and rebamipide, 100 mg t.i.d., for 7 days. The placebo group took ibuprofen, 1800 mg/day. The numbers of gastric ulcer subjects were three in the placebo group and zero in the rebamipide group. The mean modified Lanza score after ibuprofen administration was significantly higher in the placebo group than the rebamipide group (2.9±1.7 vs. 1.3±1.0, respectively; P=0.032). The GMBF of the placebo group was significantly decreased at antrum from baseline, from 2.8±0.5 to 2.0±0.5 tissue perfusion units (P=0.005). There was no difference in GMBF change in the rebamipide group. Gastric mucosal injury was correlated with GMBF reduction in antrum (r=−0.677, P=0.001). In conclusion, it is suggested that the decrease in GMBF may have been associated with NSAID-induced gastric mucosal injury, and rebamipide may have prevented NSIAD-induced gastric mucosal injury by maintaining GMBF in healthy subjects.     

急性胆道梗阻肠黏膜屏障破坏与氯离子通道-2的关系

目的:探讨急性胆道梗阻肠黏膜屏障破坏与肠上皮细胞氯离子通道-2(chloride channel-2,CLC-2)的关系.方法:建立急性胆道梗阻(阻塞性黄疸)大鼠动物模型,术后7d连续注射Lubiprostone(Lu组)、类高血糖素多肽-2(GLP-2组)、两者共同使用(Lu+GLP组),以假手术组(Sham组)和阻...     

肿瘤坏死因子受体l在暴发性肝衰竭肠黏膜屏障功能损害中的作用

肠黏膜屏障对于抵抗肠道病原微生物的侵入具有重要作用。暴发性肝衰竭（FHF）时肠黏膜屏障的通透性增加^[1-4]，细菌及其毒性产物穿透肠壁进人体内，引起自发性腹膜炎甚至败血症。FHF时肠黏膜屏障通透性的增加与肠上皮细胞紧密连接的破坏有关。我们的前期研究发现，在FHF时，肠上皮细胞间紧密连接蛋白occludin表达下降，     

人芽囊原虫感染致大鼠肠道紧密连接破坏的机制研究

目的 探讨大鼠感染人芽囊原虫后引起肠道屏障损伤的机制.方法 将30只SD大鼠随机分为对照组及感染1、3、6、9周组(感染组),每组6只.各感染组大鼠经口感染人芽囊原虫2×108个/鼠.对照组大鼠经口灌胃等体积磷酸盐缓冲液.分别于感染后1、3、6、9周收集7h大鼠尿液检测肠道通透性,随后采用颈椎脱臼法处死大鼠,取盲肠组织...     

小檗碱对酒精性肝炎小鼠“肠漏”的保护作用*

目的 探讨小檗碱（BBR）对酒精性肝炎小鼠“肠漏”的保护作用。方法 将40只雄性C57BL/6小鼠随机分为对照组、酒精组、BBR组和酒精联合BBR组,饲养8 w。采用ELISA法检测血清丙氨酸氨基转移酶（ALT）、天冬氨酸氨基转移酶（AST）和内毒素（LPS）水平。常规行组织病理学和透射电镜检查肝组织学改变和肠上皮细胞间紧密连接（TJ）超微结构。体外培养肠上皮细胞Caco-2,采用免疫荧光法检测经酒精和BBR处理后的细胞间紧密连接主要结构蛋白occludin表达。结果 酒精处理组小鼠血清ALT、AST和LPS水平分别为（46.5± 5.9） U/L、（57.0± 6.1） U/L和（0.40± 0.05） ng/ml,显著高于对照组（P< 0.01）;酒精联合BBR组血清ALT、AST和LPS水平分别为（27.6± 4.2） U/L、（31.8± 4.1） U/L和（0.24± 0.03） ng/ml,均显著低于酒精组（P< 0.05）,而与对照组无显著性差异（P> 0.05）;酒精联合BBR组肝组织细胞变性和炎细胞浸润较酒精干预组明显改善;电镜下,可见酒精处理组小鼠肠上皮细胞间紧密连接结构模糊、缝隙明显增宽,酒精联合BBR组以上改变明显减轻;酒精处理组Caco-2细胞膜occludin分布减少、中断,部分进入胞浆内,酒精联合BBR组分布虽也减少,但仍连续,无中断。结论 小檗碱能改善慢性乙醇摄入诱导的细胞膜occludin减少和上皮细胞间紧密连接结构破坏,改善“肠漏”而具有保护肝脏作用。*基金项目：北京市自然科学基金资助项目(编号：7154194）;国家自然科学基金资助项目（编号：81570536）作者单位：150086 哈尔滨市 哈尔滨医科大学附属第二医院体检中心（王洪岩）;北京市首都医科大学附属北京天坛医院消化内科（李鑫,迟程,徐有青）第一作者：王洪岩,女,31岁,医学博士,住院医师。主要从事酒精性肝病的防治研究。E-mail: xinglin_freedom@126.com     

暴发性肝衰竭时肠上皮细胞间紧密连接蛋白occludin表达下降

目的:研究暴发性肝衰竭小鼠大肠上皮细胞间紧密连接蛋白occludin表达的变化.方法:BALB/c小鼠150只随机分为生理盐水对照组(n=30)、内毒素(LPS)对照组(n=30)、D-氨基半乳糖(D-GalN)对照组(n=30)和暴发性肝衰竭(LPS GalN)组(n=60).采用D-GalN和LPS联合ip制备暴发性肝衰竭小鼠动物模型.应用免疫组织化学技术、Westernblot及实时定量PCR检测暴发性肝衰竭进程中,小鼠大肠上皮细胞间紧密连接蛋白occludin的定位、表达及mRNA的变化.结果:occludin蛋白主要沿小鼠大肠黏膜上皮细胞膜的顶端呈线状分布,在暴发性肝衰竭组小鼠,6h时occludin的阳性染色开始减少,9h时更为明显.Westernblot结果与免疫组织化学结果相一致,6h时开始下降(0.48±0.07),9h达到最低值(0.36±0.05),与生理盐水对照组(0.71±0.09)相比差异显著(P<0.05).实时定量PCR结果显示,暴发性肝衰竭小鼠2h时occludinmRNA即开始下降(0.85±0.12),6h时达到最低值(0.72±0.04),与生理盐水对照组(1.00±0.05)相比有明显差异(P<0.05),9h时有所恢复(0.93±0.10).结论:在暴发性肝衰竭过程中,大肠上皮细胞间紧密连接蛋白occludin表达下降,其mRNA也呈下调趋势.     

益生元对急性胰腺炎大鼠肠屏障功能的影响

目的 研究肠道补充益生元对急性胰腺炎肠上皮细胞紧密连接和屏障功能的影响.方法 Wistar大鼠腹腔注射左精氨酸建立AP模型,按随机数字法分组法分成对照组、AP组、益生元组.益生元组于造模前7 d开始给予益生元4 g·kg-1·d-1.建模后12 h处死大鼠,心脏取血检测血浆二胺氧化酶(DAO)活性,观察空肠病理变化、采用免疫组化方法检测紧密结合蛋白Occludin的含量.结果 AP组的血浆DAO活性为(7.29±0.68)U/L,显著高于对照组的(2.01±0.34)U/L(P＜0.01)和益生元组的(3.44±0.59)U/L(P＜0.05).AP组肠上皮occludin蛋白表达的灰度值为95.1±9.2,明显高于对照组的44.7±8.2和益生元组的59.7±7.8(P＜0.01).益生元组occludin表达也显著高于对照组(P＜0.05).结论 AP大鼠补充益生菌可增加肠上皮occludin蛋白表达,维持肠上皮紧密连接,维持正常的肠道通透性,从而达到保护肠黏膜屏障的效果.     

Combined probiotic bacteria promotes intestinal epithelial barrier function in interleukin-10-gene-deficient mice

AIM:To investigate the protective effects of combinations of probiotic(Bifico)on interleukin(IL)-10-genedeficient(IL-10 KO)mice and Caco-2 cell monolayers.METHODS:IL-10 KO mice were used to assess the benefits of Bifico in vivo.IL-10 KO and control mice received approximately 1.5×108 cfu/d of Bifico for 4 wk.Colons were then removed and analyzed for epithelial barrier function by Ussing Chamber,while an ELISA was used to evaluate proinflammatory cytokines.The colon epithelial cell line,Caco-2,was used to test the benefit of Bifico in vitro.Enteroinvasive Escherichia coli(EIEC)and the probiotic mixture Bifico,or single probiotic strains,were applied to cultured Caco-2 monolayers.Barrier function was determined by measuring transepithelial electrical resistance and tight junction protein expression.RESULTS:Treatment of IL-10 KO mice with Bifico partially restored body weight,colon length,and epithelial barrier integrity to wild-type levels.In addition,IL-10 KO mice receiving Bifico treatment had reduced mucosal secretion of tumor necrosis factor-αand interferon-γ,and attenuated colonic disease.Moreover,treatment of Caco-2 monolayers with Bifico or singlestrain probiotics in vitro inhibited EIEC invasion and reduced the secretion of proinflammatory cytokines.CONCLUSION:Bifico reduced colon inflammation in IL-10 KO mice,and promoted and improved epithelialbarrier function,enhanced resistance to EIEC invasion,and decreased proinflammatory cytokine secretion.     

肝硬化患者肠黏膜通透性与Child—Pugh分级的相关性研究

目的探讨肝硬化患者肠黏膜通透性（IP）与Child—Pugh分级的相关性及肠道去污剂对肝硬化患者肠道屏障功能及肝功能状态的影响。方法按Child—Pugh分级标准将76例肝硬化患者分为A、B、C3组,并选择30例体检者作为对照组,采用高压液相色谱法检测各组患者尿液乳果糖／甘露醇排出比（L／M）;给予76例肝硬化患者选择性肠道去污剂,比较用药前后各组患者肝功能Child—Pugh分级和肠黏膜通透性。结果肝硬化患者尿乳果N／甘露醇排出比明显高于对照组（0．208±0．025vs0．057±0．019）,肝硬化患者按Child。Pugh分级各组尿乳果糖／甘露醇排出比也均明显高于对照组,差异有显著性（P〈0．01）;采用Spearman等级相关分析发现,肝功能Child—Pu巾评分与乳果糖／甘露醇排出比呈正相关（r=0．658,P〈0．05）;给予肠道去污药物2周后肝硬化Child-Pugh分级各组患者尿液乳果糖／甘露醇排出比与治疗前比较均明显下降（P〈0．05）,各组Child—Pugh评分均有改善。结论肝硬化患者的肠黏膜通透性与肝功能Child—Pugh评分呈正相关,即肠道通透性随肝功能下降而升高,肠黏膜通透性对于肝硬化患者的诊断和治疗有临床意义。     

Tumor necrosis factor alpha increases intestinal permeability in mice with fulminant hepatic failure

AIM:To determine the effect of tumor necrosis factor alpha(TNF-α) on intestinal permeability(IP) in mice with fulminant hepatic failure(FHF),and the expression of tight junction proteins.METHODS:We selected D-lactate as an index of IP,induced FHF using D-galactosamine/lipopolysaccharide and D-galactosamine/TNF-α,assessed the results using an enzymatic-spectrophotometric method,transmission electron microscopy,immunohistochemistry,Western blotting and real-time quantitative polymerase chain reaction.The effect of the administration of antiTNF-α immunoglobulin G(IgG) antibody,before the administration of D-galactosamine/lipopolysaccharide,on TNF-α was also assessed.RESULTS:IP was significantly increased in the mouse model of FHF 6 h after injection(13.57 ± 1.70 mg/L,13.02 ± 1.97 mg/L vs 3.76 ± 0.67 mg/L,P = 0.001).Electron microscopic analysis revealed tight junction(TJ) disruptions,epithelial cell swelling,and atrophy of intestinal villi.Expression of occludin and claudin-1 mRNA was significantly decreased in both FHF models(occludin:0.57 ± 0.159 fold vs baseline,P = 0.000;claudin-1:0.3067 ± 0.1291 fold vs baseline,P = 0.003),as were the distribution density of proteins in the intestinal mucosa and the levels of occludin and claudin-1 protein(occludin:0.61 ± 0.0473 fold vs baseline,P = 0.000;claudin-1:0.6633 ± 0.0328 fold vs baseline,P = 0.000).Prophylactic treatment with antiTNF-α IgG antibody prevented changes in IP(4.50 ± 0.97 mg/L vs 3.76 ± 0.67 mg/L,P = 0.791),intestinal tissue ultrastructure,and the mRNA levels of occludin and claudin-1 expression(occludin:0.8865 ± 0.0274 fold vs baseline,P = 0.505;claudin-1:0.85 ± 0.1437 fold vs baseline,P = 0.1),and in the protein levels(occludin:0.9467 ± 0.0285 fold vs baseline,P 0.05;claudin-1:0.9533 ± 0.0186 fold vs baseline,P = 0.148).CONCLUSION:Increased in IP stemmed from the downregulation of the TJ proteins occludin and claudin-1,and destruction of the TJ in the colon,which were induced by TNF-α in FHF mice.     

Electroacupuncture improves gut barrier dysfunction in prolonged hemorrhagic shock rats through vagus anti-inflammatory mechanism

AIM:To investigate whether electroacupuncture(EA)at Zusanli(ST36)prevents intestinal barrier and remote organ dysfunction following prolonged hemorrhagic shock through a vagus anti-inflammatory mechanism.METHODS:Sprague-Dawley rats were subjected to about 45%of total blood volume loss followed by delayed fluid replacement(DFR)with Ringer lactate 3h after hemorrhage.In a first study,rats were randomly divided into six groups:(1)EAN:EA at non-channel acupoints followed by DFR;(2)EA:EA at ST36 after hemorrhage followed by DFR;(3)VGX/EA:vagotomy(VGX)before EA at ST36 and DFR;(4)VGX/EAN:VGX before EAN and DFR;(5)α-bungarotoxin(α-BGT)/EA:intraperitoneal injection ofα-BGT before hemorrhage,followed by EA at ST36 and DFR;and(6)α-BGT/EAN group:α-BGT injection before hemorrhage followed by EAN and DFR.Survival and mean arterial pressure(MAP)were monitored over the next 12 h.In a second study,with the same grouping and treatment,cytokine levels in plasma and intestine,organ parameters,gut injury score,gut permeability to 4 kDa FITC-dextran,and expression and distribution of tight junction protein ZO-1 were evaluated.RESULTS:MAP was significantly lowered after blood loss;EA at ST36 improved the blood pressure at corresponding time points 3 and 12 h after hemorrhage.EA at ST36 reduced tumor necrosis factor-αand interleukin(IL)-6 levels in both plasma and intestine homogenates after blood loss and DFR,while vagotomy or intraperitoneal injection ofα-BGT before EA at ST36reversed its anti-inflammatory effects,and EA at ST36did not influence IL-10 levels in plasma and intestine.EA at ST36 alleviated the injury of intestinal villus,the gut injury score being significantly lower than that of EAN group(1.85±0.33 vs 3.78±0.59,P<0.05).EA at ST36 decreased intestinal permeability to FITCdextran compared with EAN group(856.95 ng/mL±90.65 ng/mL vs 2305.62 ng/mL±278.32 ng/mL,P<0.05).EA at ST36 significantly preserved ZO-1 protein expression and localization at 12 h after hemorrhage.However,EA at non-channel acupoints had     

吲哚美辛联合奥沙利铂对人肺癌A549细胞株裸鼠移植瘤微淋巴管生成的影响及其化疗增敏作用

目的 研究非甾体抗炎药物吲哚美辛与化疗药物奥沙利铂对人肺癌A549细胞株裸鼠移植瘤微淋巴管生成的影响及化疗增敏作用.方法 将人肺癌A549细胞接种于裸鼠背部皮下,将裸鼠按随机数字表法分为4组:对照组、吲哚美辛组、奥沙利铂组、吲哚美辛和奥沙利铂联合用药组,并给予相应的药物.观察裸鼠生长情况,每7天测量1次肿瘤体积.42 d后处死裸鼠,切取移植瘤组织,用免疫组织化学染色法检测血管内皮生长因子C(VEGF-C)、β-连环素及生存素蛋白的表达,并测定微淋巴管密度,用实时荧光定量PCR检测VEGF-C mRNA及生存素mRNA的表达.用SPSS 16.0软件进行统计学分析,实验数据以((-x)±s)表示.多组间比较用方差分析,多组样本均数两两比较采用SNK检验,两变量的相关程度采用直线相关分析.结果 (1)吲哚美辛组、奥沙利铂组和联合用药组治疗后移植瘤体积分别为( 1322±327) mm3、(962 ±221) mm3和(611±161) mm3,低于对照组的(1664 ±318) mm3(F=23.33,P＜0.01);(2)吲哚美辛组和联合用药组VEGF-C、生存素、β-连环素蛋白的表达及微淋巴管密度积分吸光度值均低于对照组(均P＜0.05).奥沙利铂组VEGF-C蛋白含量(20 825±2067)高于对照组(16 075±875,F=97.24,P＜0.05),β-连环素蛋白和微淋巴管密度( 17 396±1693,9666±978)与对照组(9824±1181,17 588±1698)比较无明显差异;(3) VEGF-C蛋白、生存素蛋白与微淋巴管密度呈直线正相关(r值分别为0.737和0.662,均P＜0.01),β-连环素蛋白与生存素蛋白呈直线正相关(r =0.582,P＜0.01),VEGF-C mRNA的表达与其蛋白表达呈直线正相关(r =0.873,P＜0.01).结论 吲哚美辛与奥沙利铂联合应用可提高抗肿瘤及抗微淋巴管生成作用,其作用机制可能是协同抑制了VEGF-C/VEGF受体3和Wnt信号途径.     

Role of mitochondrial permeability transition in taurine deficiency-induced apoptosis

It has recently been shown that taurine deficiency leads to impaired respiratory chain function, resulting in reduced ATP generation and enhanced oxidative stress. Because cardiomyopathy develops in taurine-deficient animals, the hypothesis that mitochondrial oxidative stress may contribute to the development of cardiomyocyte dysfunction and cell death was tested. Isolated neonatal cardiomyocytes incubated in medium containing the taurine transport inhibitor, beta-alanine, lost nearly one-half of their cellular taurine content after 48 h. Accompanying the loss of taurine was a time-dependent increase in apoptosis, which was prevented by the mitochondrial permeability transition inhibitor, cyclosporin A. Two taurine-dependent factors, oxidative stress and calcium overload, serve as important regulators of the mitochondrial permeability transition. Although taurine deficiency slowed the removal of calcium from the cytosol, it had no effect on diastolic calcium content and only modestly reduced systolic calcium content, suggesting that calcium overload is not the trigger for mitochondrial permeability transition pore formation. On the other hand, the glutathione redox ratio was significantly altered in the taurine-deficient cardiomyocyte, suggesting that oxidative stress is the primary initiator of mitochondrial permeability transition and apoptosis in the taurine-deficient cardiomyocyte.