Schistosoma japonicum ova maintains epithelial barrier function during experimental colitis

AIM: To evaluate the impacts of Schistosoma japonicum (S. japonicum) ova on the tight junction barriers in a trinitrobenzenesulfonic acid (TNBS)-induced colitis model.METHODS: Balb/c mice were randomly divided into three groups: control group; TNBS⁺ova^- group and TNBS⁺ova⁺ group. TNBS was used intracolonic to induce colitis and mice of the TNBS⁺ova⁺ group were pre-exposed to S. japonicum ova as a prophylactic intervention. Colon inflammation was quantified using following variables: mouse mortality, weight loss, colon extent and microscopic inflammation score. Serum expression of tumor necrosis factor-α and interferon-γ were assessed to evaluate the systemic inflammatory response. NOD2 and its mRNA were also tested. Bacterial translocations were tested by culturing blood and several tissues. ZO-1 and occludin were chosen as the representations of tight junction proteins. Both the proteins and mRNA were assessed.RESULTS: Ova pre-treatment contributed to the relief of colitis and decreased the mortality of the models. NOD2 expression was significantly downregulated when pretreated with the ova. The TNBS injection caused a significant downregulation of ZO-1 and occludin mRNA together with their proteins in the colon; ova pre-exposure reversed these alterations. Treatment with S. japonicum ova in the colitis model caused lower intestinal bacterial translocation frequency.CONCLUSION: S. japonicum ova can maintain epithelial barrier function through increasing tight junction proteins, thus causing less exposure of NOD2 to the luminal antigens which may activate a series of inflammatory factors and induce colitis.     

The effects of electromagnetic pulse on the protein levels of tight junction associated-proteins in the cerebral cortex, hippocampus, heart, lung, and testis of rats

Objective To investigate changes in the expression of tight junction (TJ) proteins in the cerebral cortex,hippocampus,heart,lung,and testes of rats after exposure to electromagnetic pulse (EMP).Methods Eighteen adult male Sprague-Dawley rats were divided into sham and exposure groups.The exposure groups received EMP at 200 kV/m for 200 pulses with a repetition rate of 1 Hz.The expression of TJ proteins (ZO-1,occludin,actin) in the several organs was examined by western blotting.Results ZO-1 levels in the ce...     

Vascular permeability in ocular disease and the role of tight junctions

Vascular permeability is closely linked with angiogenesis in a number of pathologies. In the retina, the normally well-developed blood-retinal barrier is altered in a host of eye diseases preceding or commensurate with angiogenesis. This review examines the literature regarding the tight junction complex that establishes the blood-retinal barrier focusing on the transmembrane proteins occludin and the claudin family and the membrane associated protein zonula occludens. The changes observed in these proteins associated with vascular and epithelial permeability is discussed. Finally, novel literature addressing the link between the tight junction complex and angiogenesis is considered.     

Altered integrity and decreased expression of hepatocyte tight junctions in rifampicin-induced cholestasis in mice

Rifampicin is a well-known hepatotoxicant, but little is known about the mechanism of rifampicin-induced hepatotoxicity. The aim of this study was to characterize the expression and localization of hepatocyte tight junctions in rifampicin-induced cholestasis in mice. Cholestasis was induced by administration of rifampicin (200 mg/kg) for 7 consecutive days or treatment with a single dose of rifampicin (200 mg/kg) by gastric intubation. The expression of mRNA for hepatic zonula occludens (ZO)-1, ZO-2, ZO-3, occludin and claudin-1 was determined using RT-PCR. Localization of ZO-1 and occludin was detected using immunofluorescence. Results showed that there was an 82-fold increase in the conjugated bilirubin in serum in rifampicin-treated mice. In addition, an 8-fold increase in total bile acid in serum was observed after a seven-day administration of rifampicin. The integrity of hepatocyte ZO-1 and occludin was altered by a seven-day administration of rifampicin. Importantly, the integrity and intensity of hepatocyte tight junctions were altered as early as 30 min after a single dose of rifampicin. The expression of hepatic ZO-1 and ZO-2 mRNA was significantly decreased, beginning as early as 30 min and remaining a lower level 12 h after a single dose of rifampicin. Taken together, these results suggest that the altered integrity and internalization of hepatocyte tight junctions are associated with rifampicin-induced cholestasis.     

Tight junctions and tight junction proteins in mammalian epidermis

Tight junctions (TJ) are barrier forming cell-cell junctions that are found in a variety of cell types and tissues but their existence in mammalian epidermis has been shown only in the last years. A variety of TJ proteins were identified in mammalian epidermis, comprising several members of the claudin family, occludin, and JAM-A as well as ZO-1 and MUPP-1. TJ proteins exhibit complex expression and localization patterns in the epidermis. Nonetheless, even though several TJ proteins are found in various layers, typical TJ structures are only found in the stratum granulosum. TJ are important for barrier function of the skin, especially for inside-out barrier. In addition, TJ proteins might also be involved in additional functions in epidermal cells. Localization and expression of TJ proteins are altered in several skin diseases, e.g. psoriasis. Meanwhile several TJ modulators are known from simple epithelia. We discuss their putative usability for drug delivery into and through the skin.     

艾灸对克罗恩病大鼠结肠肿瘤坏死因子-α含量及艾灸鼠结肠上清液对培养的结肠上皮细胞内紧密连接蛋白及其基因表达的影响

目的:通过观察温和灸、隔药灸对肿瘤坏死因子-α(TNF-α)体外诱导大鼠结肠上皮细胞紧密连接——咬合蛋白(occludin)、闭合蛋白1(claudin-1)和闭锁蛋白1(zonula occludens-1,ZO-1)及其基因表达的影响,探讨艾灸对肠上皮屏障损伤的修复/保护机制。方法:将SD大鼠随机分成正常组、模型组、温和灸组、隔药灸组和西药组,各12只。采用三硝基苯磺酸制备克罗恩病(Crohn’s Disease,CD)大鼠模型。温和灸组与隔药灸组选择"天枢""气海"穴分别予以温和灸和隔药灸,每日1次,共治疗14次;西药组以柳氮磺胺吡啶溶液灌胃,每日2次,共14次。治疗结束后剖取各CD组大鼠结肠,制备结肠黏膜上清液;正常组纯化并培养结肠上皮细胞建立肠上皮屏障体外模型。将各CD组结肠黏膜上清液分别与正常大鼠结肠上皮细胞混合培养1周,采用ELISA法检测各组结肠黏膜上清液TNF-α含量,Western blot和荧光定量PCR法观察其对CD大鼠体外结肠上皮紧密连接occludin、claudin-1和ZO-1及其mRNA表达的影响。结果:CD模型组较正常组大鼠结肠黏膜上清液中TNF-α含量有显著增高(P<0.01),温和灸、隔药灸和柳氮磺胺吡啶治疗后TNF-α含量显著降低(均P<0.01),其中温和灸、隔药灸组优于西药组(均P<0.05);与此同时,温和灸、隔药灸和西药组结肠黏膜TNF-α上清液体外诱导大鼠结肠上皮紧密连接occludin、claudin-1和ZO-1及其mRNA表达较模型组有显著增高(P<0.01,P<0.05),且隔药灸、温和灸两组也优于西药组(均P<0.05)。结论:艾灸(隔药灸、温和灸)可能是通过降低CD大鼠结肠黏膜异常增高的TNF-α,进而促进或调节结肠上皮紧密连接occludinc、laudin-1和ZO-1及其mRNA表达,达到修复/保护肠上皮屏障损伤的目的。     

Tight junction proteins contribute to barrier properties in human pleura

The permeability of pleural mesothelium helps to control the volume and composition of the liquid lubricating pleural surfaces. Information on pleural barrier function in health and disease, however, is scarce. Tissue specimens of human pleura were mounted in Ussing chambers for measurement of transmesothelial resistance. Expression of tight junction (TJ) proteins was studied by Western blots and immune fluorescence confocal microscopy. Both visceral and parietal pleura showed barrier properties represented by transmesothelial resistance. Occludin, claudin-1, -3, -5, and -7, were detected in visceral pleura. In parietal pleura, the same TJ proteins were detected, except claudin-7. In tissues from patients with pleural inflammation these tightening claudins were decreased and in visceral pleura claudin-2, a paracellular channel former, became apparent. We report that barrier function in human pleura coincides with expression of claudins known to be key determinants of epithelial barrier properties. In inflamed tissue, claudin expression indicates a reduced barrier function.     

Gut epithelial barrier damage caused by dishwasher detergents and rinse aids

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小檗碱对葡聚糖硫酸钠诱导的溃疡性结肠炎小鼠模型的治疗作用及其对肠黏膜闭合蛋白的影响

目的观察小檗碱对于葡聚糖硫酸钠( DSS)诱导的溃疡性结肠炎( UC)小鼠模型的治疗作用及其对肠黏膜闭合蛋白(occludin)表达的影响。方法于 2021年 6—12月建立 DSS诱导的小鼠 UC模型进行基础性研究。将 30只 BALB/c小鼠采用抽签法随机平均分为对照组、模型组和治疗组，除对照组(不造模、不干预)外，其余两组小鼠自由饮用 3%DSS溶液 7d建立急性 UC模型。治疗组每只小鼠每日予小檗碱( 20 mg/kg)灌胃，其余两组则每日予双蒸水 0.2 mL灌胃。使用疾病活动系数( DAI)评估小鼠临床症状的严重程度，结肠黏膜损伤评分(CMDI)、组织病理评分及结肠组织髓过氧化物酶( MPO)对结肠炎症程度进行评估。用蛋白质印迹法及免疫组织化学染色观察结肠黏膜中 occludin的表达情况。结果对照组、模型组及治疗组第 7日 DAI评分分别为( 0.00±0.00)、(3.23±0.94)、(1.87±0.67)分( P<0.001)；对照组、模型组及治疗组病理组织学评分分别为( 0.40±0.84)、(8.20±1.70)、(4.85±0.97)分( P<0.001)；对照组、模型组及治疗组 MPO分别为( 1.94±0.58)、(4.46±1.13)、(3.11±1.05)U/g(P<0.001)。与对照组相比，模型组小鼠的 DAI、CMDI及组织病理评分及 MPO升高，而 occludin蛋白水平降低；而与模型组相比，治疗组小鼠的临床症状及肠道的炎症程度明显减轻。结论小檗碱可能通过上调 occludin蛋白的表达保护肠黏膜屏障，进而改善 DSS诱导小鼠 UC模型的炎症程度。