PDF(Pubmed)
Abstract：
The underlying pathophysiology of irritable bowel syndrome (IBS) is still unclear. Our aim was to investigate the pathophysiological mechanisms of diarrhea, constipation, and antigen uptake in mixed-type IBS (IBS-M).
Colonoscopic biopsies were obtained from IBS-M patients. Epithelial transport and barrier function of colonic mucosae were characterized in Ussing chambers using impedance spectroscopy. Mucosal permeability to macromolecules was measured. Western blotting for tight junction (TJ) proteins was performed and their subcellular localization was visualized by confocal microscopy. RNA-sequencing was performed for gene expression and signaling pathway analysis.
In IBS-M, epithelial resistance and ENaC-dependent sodium absorption were unchanged, while short-circuit current reflecting chloride secretion was reduced. Concomitantly, epithelial permeability for fluorescein and FITC-dextran-4000 increased. TJ protein expression of occludin decreased, whereas claudins were unaltered. Confocal microscopy revealed the de-localization of tricellulin from tricellular TJs. Involved pathways were detected as proinflammatory cytokine pathways, LPS, PGE2, NGF, and vitamin D.
Decreased anion secretion explains constipation in IBS-M, while ion permeability and sodium absorption were unaltered. Reduced occludin expression resulted in the delocalization of tricellulin from the tricellular TJ, leading to increased macromolecular permeability that contributes to antigen influx into the mucosa and perpetuates a low-grade inflammatory process.
Colonoscopic biopsies were obtained from IBS-M patients. Epithelial transport and barrier function of colonic mucosae were characterized in Ussing chambers using impedance spectroscopy. Mucosal permeability to macromolecules was measured. Western blotting for tight junction (TJ) proteins was performed and their subcellular localization was visualized by confocal microscopy. RNA-sequencing was performed for gene expression and signaling pathway analysis.
In IBS-M, epithelial resistance and ENaC-dependent sodium absorption were unchanged, while short-circuit current reflecting chloride secretion was reduced. Concomitantly, epithelial permeability for fluorescein and FITC-dextran-4000 increased. TJ protein expression of occludin decreased, whereas claudins were unaltered. Confocal microscopy revealed the de-localization of tricellulin from tricellular TJs. Involved pathways were detected as proinflammatory cytokine pathways, LPS, PGE2, NGF, and vitamin D.
Decreased anion secretion explains constipation in IBS-M, while ion permeability and sodium absorption were unaltered. Reduced occludin expression resulted in the delocalization of tricellulin from the tricellular TJ, leading to increased macromolecular permeability that contributes to antigen influx into the mucosa and perpetuates a low-grade inflammatory process.
摘要：
背景：肠易激综合征（IBS）的病理生理学尚不清楚。我们的目的是研究腹泻的病理生理机制，便秘,以及混合型IBS(IBS-M)中的抗原摄取。
方法：结肠镜活检取自IBS-M患者。使用阻抗谱在Ussing室中表征了结肠粘膜的上皮运输和屏障功能。测量对大分子的粘膜渗透性。进行紧密连接（TJ）蛋白的蛋白质印迹，并通过共聚焦显微镜观察其亚细胞定位。进行RNA测序用于基因表达和信号通路分析。
结果：在IBS-M中，上皮阻力和ENaC依赖性钠吸收没有变化，而反映氯化物分泌的短路电流减少。同时，荧光素和FITC-葡聚糖-4000的上皮通透性增加。TJ蛋白表达降低,而claudins是不变的。共聚焦显微镜显示三细胞蛋白从三细胞TJ中的去定位。所涉及的途径被检测为促炎细胞因子途径，LPS,PGE2,NGF,
结论：阴离子分泌减少解释了IBS-M的便秘，而离子渗透性和钠吸收没有改变。减少的occludin表达导致三细胞蛋白从三细胞TJ离域，导致大分子通透性增加，这有助于抗原流入粘膜并维持低度炎症过程。
方法：结肠镜活检取自IBS-M患者。使用阻抗谱在Ussing室中表征了结肠粘膜的上皮运输和屏障功能。测量对大分子的粘膜渗透性。进行紧密连接（TJ）蛋白的蛋白质印迹，并通过共聚焦显微镜观察其亚细胞定位。进行RNA测序用于基因表达和信号通路分析。
结果：在IBS-M中，上皮阻力和ENaC依赖性钠吸收没有变化，而反映氯化物分泌的短路电流减少。同时，荧光素和FITC-葡聚糖-4000的上皮通透性增加。TJ蛋白表达降低,而claudins是不变的。共聚焦显微镜显示三细胞蛋白从三细胞TJ中的去定位。所涉及的途径被检测为促炎细胞因子途径，LPS,PGE2,NGF,
结论：阴离子分泌减少解释了IBS-M的便秘，而离子渗透性和钠吸收没有改变。减少的occludin表达导致三细胞蛋白从三细胞TJ离域，导致大分子通透性增加，这有助于抗原流入粘膜并维持低度炎症过程。
