梗阻性黄疸肠黏膜屏障损伤病理生理机制的研究进展

肠黏膜屏障具有机械屏障、化学屏障、生物屏障、免疫屏障等功能,是防止肠道内的有害物质和病原体进入机体内环境,维持内环境稳定的一道重要屏障.梗阻性黄疸(obstructive jaundice,OJ)患者病死率和并发症发生率居高不下,主要原因是败血症和肾功能衰竭.临床与基础研究证实OJ存在肠黏膜屏障损伤,其主要病理生理机制是肠黏膜通透性增加、肠黏膜上皮氧化应激损伤及肠源性内毒素血症,具体机制尚未明确.本文对OJ引起的肠黏膜屏障损伤的病理生理机制作一综述.     

炎症性肠病肠黏膜屏障损伤机制

肠黏膜屏障是指将肠腔内细菌、抗原等物质与肠黏膜固有层免疫细胞隔离开,避免固有层免疫细胞激活的肠黏膜结构,要由肠黏膜基底膜、上皮细胞层及其表面的黏液层所构成.炎症性肠病(innammatory bowel diseasc,IBD)肠黏膜屏障损伤的机制为:IBD发病时,肠黏膜所产生的大量炎症细胞因子、炎症介质等损伤肠上皮细胞,诱导上皮细胞凋亡;影响上皮细胞紧密连接蛋白的表达及分布,破坏上皮细胞间紧密连接;抑制黏蛋白的产生,破坏上皮细胞表面的黏液层,造成肠黏膜屏障障碍.     

益生菌对肠黏膜屏障紧密连接蛋白保护作用的研究进展

正常肠道除具有消化吸收食物及蠕动功能外,还有激素分泌、免疫调节和黏膜屏障功能。肠上皮细胞间紧密连接在调节肠黏膜屏障通透性和维持肠上皮细胞紧密性中发挥重要的作用。紧密连接是包含众多蛋白的复合体,可调节细胞旁的通透性,其中跨膜蛋白claudin-1最具代表性。研究报道,在炎症性肠病、肠道感染时,由于紧密连接崩解导致肠黏膜屏障断裂破坏,引起肠上皮细胞旁通透性增加。有研究发现肠道菌群失调与肠黏膜屏障功能失调有关。益生菌对因紧密连接蛋白崩解导致的肠黏膜屏障破坏具有保护作用,此文就相关研究进展作一综述。     

肠黏膜屏障功能异常与炎症性肠病

正常肠黏膜屏障由机械屏障、化学屏障、免疫屏障、生物屏障构成,能有效阻止肠道内细菌和内毒素易位。检测肠黏膜通透性可反映肠黏膜屏障功能。肠黏膜屏障受营养、感染、损伤等多种因素影响。研究表明肠黏膜屏障功能损伤与炎症性肠病（IBD）密切相关,然而其为IBD的病因还是继发性改变目前仍存在争议。保护和恢复肠黏膜屏障功能对IBD的治疗具有重要意义。     

梗阻性黄疸对肠黏膜屏障的影响

肠黏膜屏障包括机械屏障、免疫屏障、生物屏障和化学屏障,四者共同维持肠黏膜的正常防御功能。梗阻性黄疸患者引起肠黏膜屏障损伤,导致细菌移位及内毒素血症,后者又加重屏障功能障碍。本文主要就梗阻性黄疸对肠黏膜屏障损伤的机制作一综述。     

乌司他丁对急性坏死性胰腺炎大鼠肠黏膜屏障的保护作用

目的 观察乌司他丁干预急性坏死性胰腺炎(ANP)大鼠后血TNF-α、二胺氧化酶(DAO)及肠黏膜组织紧密连接蛋白-1( zonula occludens-1,ZO-1)表达水平的变化,探讨其可能机制.方法 按完全随机法将SD雄性大鼠随机分为假手术组、ANP组及乌司他丁组.采用5％牛磺胆酸钠逆行注入胆胰管的方法制模.制模后6、24h取血检测TNF-α、DAO活性,胰腺及回肠组织常规病理检查,RT-PCR及免疫组化法检测回肠组织ZO-1 mRNA及蛋白的表达.结果 术后6h,ANP组胰腺大片坏死,大量炎细胞浸润;回肠黏膜绒毛上皮坏死、血管出血、炎细胞浸润.乌司他丁组的胰腺及回肠组织损伤较ANP组减轻.假手术组、ANP组、乌司他丁组术后6h的血TNF-α水平分别为(10.83±0.96)、( 181.89±4.93)、(128.23±2.40) ng/L;DAO活性分别为(354.79±3.67)、(117.21±5.58)、(282.98±9.12) U/L;回肠组织ZO-1蛋白表达量分别为(10.00±1.87)、(1.20±0.84)、(5.80±2.86)分;Z(O)-1 mRNA表达量为0.878±0.015、0.466±0.023、0.778±0.033.ANP组血TNF-α水平较假手术组明显升高,DAO活性、回肠组织ZO-1 mRNA及蛋白表达较对照组明显降低(P值均＜0.05);乌司他丁组的血TNF-α水平较ANP组降低,DAO活性、回肠组织ZO-1 mRNA及蛋白表达较ANP组明显升高(P值均＜0.05).结论 乌司他丁可能通过抑制TNF-α的过度释放、提高血浆中DAO活性,从而上调回肠组织中ZO-1 mRNA和蛋白表达,进而保护肠黏膜屏障.     

急性胰腺炎大鼠肠黏膜屏障损伤、MLCK/p-MLC信号通路活性变化及其与抗菌肽的关系

目的 观察急性胰腺炎（AP）大鼠肠黏膜屏障损伤情况和MLCK/p-MLC2信号通路活性变化,探讨MLCK/p-MLC2信号通路激活与抗菌肽的关系。方法 将24只SD大鼠分为对照组6只和AP组18只,采用胰胆管逆行注射5%牛磺胆酸钠溶液进行AP造模,对照组仅翻动胰腺后复位。AP组于造模后6、12、24 h各取6只大鼠进行解剖和取材,对照组于造模后6 h取材。采用ELISA法检测血清淀粉酶、脂肪酶水平,HE染色法观察回肠组织病理改变,RT-qPCR法检测回肠组织潘氏细胞分泌的抗菌肽REG3γ、α-防御素5、溶菌酶mRNA表达水平,Western blotting法检测回肠组织紧密连接蛋白ZO-1、Claudin-1及MLCK/p-MLC2信号通路相关蛋白MLCK、p-MLC2蛋白表达水平。结果 AP组造模后6、12、24 h血清淀粉酶、脂肪酶水平均高于对照组,其中12 h和24 h血清淀粉酶、脂肪酶水平高于6 h,且24 h高于12 h(P均<0.05)。对照组回肠黏膜完整,绒毛结构规整正常;AP组回肠黏膜出现不同程度的断裂缺失、间质水肿、炎性细胞浸润。AP组造模后6、12、24 h...     

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.     

姜黄素对梗阻性黄疸大鼠肠黏膜屏障的保护作用

目的:探讨姜黄素对梗阻性黄疸(obstructive jaundice,OJ)大鼠小肠黏膜屏障的保护作用.方法:将♂SD大鼠随机分为3组:假手术对照(sham operation,SO)组、OJ组、姜黄素治疗(curcumin treatment,Cur)组.光镜下观察小肠组织形态学改变,测量肠绒毛高度和黏膜厚度,采用鲎试剂法检测血浆内毒素水平,采用放射免疫法检测血清肿瘤坏死因子-α(tumor necrosis factor-α,T N F-α)、白介素-6(interleukin-6,I L-6)水平,应用分光光度法测定肠组织二胺氧化酶(diamine oxidase,DAO)活性,采用免疫组织化学方法检测小肠组织中核因子-κB(nuclear factor kappa B,NF-κB)和细胞黏附分子-1(intercellular adhesion molecule-1,ICAM-1)的表达.结果:OJ组肠黏膜绒毛排列紊乱,绒毛稀疏、断裂,肠黏膜萎缩,绒毛水肿,部分上皮细胞坏死脱落,并可见炎性细胞浸润;Cur组肠黏膜病变较OJ组明显减轻,肠黏膜绒毛排列整齐,肠黏膜增厚,绒毛轻度水肿,未见明显上皮细胞脱落,炎性细胞浸润减少;与S O组比较,O J组内毒素、T N F-α、I L-6明显增高(P0.01),DAO活性、肠绒毛高度及黏膜厚度明显降低(P0.01);Cur组较OJ组内毒素、TNF-α、IL-6明显下降(P0.05或0.01),D A O活性、肠绒毛高度及黏膜厚度明显升高(P0.05).OJ组回肠黏膜NF-κB及ICAM-1表达明显高于SO组(P0.01);Cur组NF-κB及ICAM-1表达明显低于OJ组(P0.05或0.01).结论:姜黄素通过抑制NF-κB、TNF-α、IL-6和ICAM-1等炎症介质,对小肠黏膜屏障具有保护作用.     

Glucagon-like peptide-2 protects impaired intestinal mucosal barriers in obstructive jaundice rats

AIM: To observe the protective effect of glucagon-like peptide-2(GLP-2) on the intestinal barrier of rats with obstructive jaundice and determine the possible mechanisms of action involved in the protective effect.METHODS: Thirty-six Sprague-Dawley rats were randomly divided into a sham operation group, an obstructive jaundice group, and a GLP-2 group; each group consisted of 12 rats. The GLP-2 group was treated with GLP-2 after the day of surgery, whereas the other two groups were treated with the same concentration of normal saline. Alanine aminotransferase(ALT), total bilirubin, and endotoxin levels were recorded at 1, 3, 7, 10 and 14 d. Furthermore, on the 14 th day, body weight, the wet weight of the small intestine, pathological changes of the small intestine and the immunoglobulin A(Ig A) expressed by plasma cells located in the small intestinal lamina propria were recorded for each group.RESULTS: In the rat model, jaundice was obvious, and the rats’ activity decreased 4-6 d post bile duct ligation. Compared with the sham operation group, the obstructive jaundice group displayed increased yellow staining of abdominal visceral serosa, decreased small intestine wet weight, thinning of the intestinal muscle layer and villi, villous atrophy, uneven height, fusion, partial villous epithelial cell shedding, substantial inflammatory cell infiltration and significantly reduced Ig A expression. However, no significant gross changes were noted between the GLP-2 and sham groups. With time, the levels of ALT, endotoxin and bilirubin in the GLP-2 group were significantly increased compared with the sham group(P < 0.01). The increasing levels of the aforementioned markers were more significant in the obstructive jaundice group than in the GLP-2 group(P < 0.01).CONCLUSION: GLP-2 reduces intestinal mucosal injuries in obstructive jaundice rats, which might be attributed to increased intestinal Ig A and reduced bilirubin and endotoxin.     

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.     

Experimental obstructive jaundice alters claudin-4 expression in intestinal mucosa： Effect of bombesin and neurotensin

AIM: To investigate the influence of experimental obstructive jaundice and exogenous bombesin (BBS) and neurotensin (NT) administration on the expression of the tight junction (TJ)-protein claudin-4 in intestinal epithelium of rats. METHODS: Forty male Wistar rats were randomly divided into five groups:Ⅰ= controls,Ⅱ= sham operated,Ⅲ= bile duct ligation (BDL),Ⅳ= BDL BBS (30μg/kg per d),Ⅴ= BDL NT (300μg/kg per d). At the end of the experiment on d 10, endotoxin was measured in portal and aortic blood. Tissue sections of the terminal ileum were examined histologically and immunohistochemically for evaluation of claudin-4 expression in intestinal epithelium. RESULTS: Obstructive jaundice led to intestinal barrier failure demonstrated by significant portal and aortic endotoxemia. Claudin-4 expression was significantly increased in the upper third of the villi in jaundiced rats and an upregulation of its lateral distribution was noted. Administration of BBS or NT restored claudin-4 expression to the control state and significantly reduced portal and aortic endotoxemia. CONCLUSION: Experimental obstructive jaundice increases claudin-4 expression in intestinal epithelium, which may be a key factor contributing to the disruption of the mucosal barrier. Gut regulatory peptides BBS and NT can prevent this alteration and reduce portal and systemic endotoxemia.     

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.     

鱼油对重症急性胰腺炎大鼠肠黏膜屏障的影响

目的:探讨 -3鱼油脂肪乳剂对重症急性胰腺炎(SAP)大鼠早期肠黏膜功能屏障的影响.方法:♂Wistar大鼠30只随机分为:假手术组(So组,n=10),鱼油治疗组(F组,n=10)和生理盐水治疗组(N组,n=10).通过胰管逆行注射法建成SAP模型,并分别尾静脉注射 -3鱼油脂肪乳剂和生理盐水治疗.检测大鼠血浆D-乳...     

Effects of Lactobacillus plantarum on gut barrier function in experimental obstructive jaundice

AIM: To investigate the mechanisms of Lactobacillus plantarum (L. plantarum) action on gut barrier in preoperative and postoperative experimental obstructive jaundice in rats.METHODS: Forty rats were randomly divided into groups of sham-operation, bile duct ligation (BDL), BDL + L. plantarum, BDL + internal biliary drainage (IBD), and BDL + IBD + L. plantarum. Ten days after L. plantarum administration, blood and ileal samples were collected from the rats for morphological examination, and intestinal barrier function, liver function, intestinal oxidative stress and protein kinase C (PKC) activity measurement. The distribution and expression of the PKC and tight junction (TJ) proteins, such as occludin, zonula occludens-1, claudin-1, claudin-4, junction adhesion molecule-A and F-actin, were examined by confocal laser scanning microscopy, immunohistochemistry, Western blotting, real-time fluorescent quantitative polymerase chain reaction assay.RESULTS: L. plantarum administration substantially restored gut barrier, decreased enterocyte apoptosis, improved intestinal oxidative stress, promoted the activity and expression of protein kinase (BDL vs BDL + L. plantarum, 0.295 ± 0.007 vs 0.349 ± 0.003, P < 0.05; BDL + IBD vs BDL + IBD + L. plantarum, 0.407 ± 0.046 vs 0.465 ± 0.135, P < 0.05), and particularly enhanced the expression and phosphorylation of TJ proteins in the experimental obstructive jaundice (BDL vs BDL + L. plantarum, 0.266 ± 0.118 vs 0.326 ± 0.009, P < 0.05). The protective effect of L. plantarum was more prominent after internal biliary drainage ( BDL + IBD vs BDL + IBD + L. plantarum, 0.415 ± 0.105 vs 0.494 ± 0.145, P < 0.05).CONCLUSION: L. plantarum can decrease intestinal epithelial cell apoptosis, reduce oxidative stress, and prevent TJ disruption in biliary obstruction by activating the PKC pathway.     

肠黏膜屏障损伤与保护分子机制研究进展

介绍肠黏膜屏障损伤因素的分子机制,如内毒素及氧自由基、炎症介质和细胞因子如白细胞介素（interleukin）、肿瘤坏死因子-α（TNF-α）、核转录因子kappa B、TOLL样受体（TLRs）和NOD受体通路、高迁移率族蛋白B1、烟酰胺腺嘌呤二核苷酸磷酸（NADPH）氧化酶（NOX）等。对肠黏膜屏障的保护分子机制如肠上皮紧密连接蛋白、白介素家族、其它保护性调控因子等作出介绍。     

Intestinal failure in obstructive jaundice

TO THE EDITOR We read with great interest the article by Ding LA and LiJS, which aimed to review the current knowledge on the physiology of normal intestinal barrier function and highlight the role of intestinal failure after various injurious insults in the development of septic complications or multiple organ failure with subsequent rapid clinical deterioration or even death.     

肠屏障功能障碍的研究现状与展望

肠屏障功能障碍正日益受到关注,多种疾病均可引起肠屏障功能障碍,促使细菌移位,加重原发病,形成恶性循环。此文就肠屏障功能障碍的发病机制、检测方法和治疗措施进展作一综述。