TPN相关肠屏障损伤小鼠模型的建立与应用

Total parenteral nutrition (TPN), as an important clinical treatment, has saved a large number of critically ill patients. But TPN associated intestinal barrier damage, which is one of the important reasons leading to TPN related complications, limits the clinical application and weakens the therapeutic effect of TPN. By now, the research progress related pathogenesis and prevention strategy has been limited. Currently, most of the TPN related intestinal barrier damage models are made in normal animals which are not only inconsistent with clinical practice but also lack of comprehensive mechanism evaluation about intestinal barrier damage. This project took the lead to adopt C57BL/6J mice after intestinal injury induced by DSS to establish TPN associated intestinal barrier damage mice model: (1) to build a solid TPN associated intestinal barrier damage animal model; (2) to study the intestinal pathophysiology of the animal model systematically; (3) to compare the differences of intestinal barrier function after administering TPN between the different strain mice and human specimens, meanwhile, to determine whether the mouse model is in accordance with the clinical practice; (4) to study the intestinal pathophysiology and the related mechanism of the remote organs such as liver and skeletal muscle after administering parenteral nutrition in mice. This project will establish the animal model platform to study the mechanism of intestinal mucosa injury and organ dysfunction, to make the preventions and control strategies and to guide the clinical application of TPN in reasonable way. Therefore, this project will promote the progress of TPN associated intestinal barrier damage in the perspective of translational medicine and have broad application prospects.

全肠外营养（TPN）作为临床重要的治疗手段，挽救了大量重症病人的生命，但TPN相关的肠屏障损伤是导致TPN并发症的重要原因，也限制了TPN的临床应用和疗效，其发病机理和防治研究进展缓慢。目前使用的TPN相关肠屏障损伤模型在正常动物中建立，既与临床实际不符又缺乏肠屏障损伤的全面评估机制。本项目率先在C57BL/6J小鼠上通过DSS诱导肠道损伤后进行TPN干预，在此基础上建立肠屏障损伤动物模型：①建立了稳定的TPN相关肠屏障损伤小鼠模型；②系统性观察TPN相关肠屏障损伤动物模型肠道的病理生理改变；③比较不同品系小鼠模型及人体标本TPN后肠屏障功能损伤差异，确定模型与临床的符合度；④应用该模型研究肠外营养相关肝脏、骨骼肌等远隔器官的病理生理改变及机制。本课题为TPN导致肠屏障损伤及器官功能障碍等的发病机制研究，防治策略制定及TPN临床合理应用提供模式动物平台，具有重要转化医学意义和广阔应用前景。

全肠外营养（TPN）作为临床重要的治疗手段，挽救了大量重症病人的生命，但TPN相关的肠屏障损伤是导致TPN并发症的重要原因，也限制了TPN的临床应用和疗效，其发病机理和防治研究进展缓慢。目前使用的TPN相关肠屏障损伤模型在正常动物中建立，既与临床实际不符又缺乏肠屏障损伤的全面评估机制。.本项目为了模拟临床上因肠道功能障碍而接受TPN病人的疾病特征，通过DSS诱导结肠炎大鼠/小鼠模型，然后静脉置管建立稳定的TPN大鼠/小鼠模型，通过蛋白组学、磷酸化蛋白组学、代谢组学和16sRNA测序等实验手段，完成了TPN相关肠屏障功能障碍、糖代谢紊乱、肺功能和肝功能障碍等并发症的表型观察和机制研究。 .本项研究结果显示肠道菌群紊乱是引起TPN相关肠黏膜屏障损伤及代谢并发症的重要原因。其中具体机制为：长期使用TPN引起小鼠肠道菌群改变，色氨酸代谢产物减少，AhR活化降低，进一步引起ILC3s数量减少，IL-22分泌障碍，诱发潘氏细胞功能降低导致肠黏膜屏障损伤；此外，色氨酸代谢产物在诱导TPN相关糖代谢障碍中也发挥重要作用。.关于TPN相关肝损伤的机制研究，本项目得出结果如下：TPN引起的 NDUFS1表达下调通过诱导氧化应激参与肠外营养相关性肝病的发生过程，而Pyrin炎性小体活性的改变，作为 NDUFS1表达下调及氧化应激的下游效应，可能成为治疗或预防肠外营养相关性肝病的潜在靶点；此外，肝脏PP2A-Ca的减少通过增强AKT2的磷酸化水平，抑制AMPK酶活性，从而抑制肝脏脂肪酸的β氧化，也是引起肠外营养相关肝损伤的重要机制。同时，肝脏内过表达或增强PP2A活性可以改善肠外营养相关肝脏脂肪变性。.除了肠黏膜屏障损伤，代谢性障碍及肝损伤外，本项目还发现，长期使用TPN可导致明显的肺损伤，主要表现为肺泡上皮细胞间紧密连接蛋白表达降低、肺组织病例结构破坏，肺组织通透性增加，肺泡灌洗液中菌群紊乱，菌群发生易位。同时进一步研究表明，TPN相关肺组织的损伤作用可能与肺组织自噬受抑制密切相关，使用蕾帕霉素可显著缓解TPN相关肺损伤。

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