Fondazione Policlinico Universitario A Gemelli IRCCS, Rome 00168, Italy.
World J Gastroenterol. 2019 Sep 7;25(33):4814-4834. doi: 10.3748/wjg.v25.i33.4814.
The intimate connection and the strict mutual cooperation between the gut and the liver realizes a functional entity called gut-liver axis. The integrity of intestinal barrier is crucial for the maintenance of liver homeostasis. In this mutual relationship, the liver acts as a second firewall towards potentially harmful substances translocated from the gut, and is, in turn, is implicated in the regulation of the barrier. Increasing evidence has highlighted the relevance of increased intestinal permeability and consequent bacterial translocation in the development of liver damage. In particular, in patients with non-alcoholic fatty liver disease recent hypotheses are considering intestinal permeability impairment, diet and gut dysbiosis as the primary pathogenic trigger. In advanced liver disease, intestinal permeability is enhanced by portal hypertension. The clinical consequence is an increased bacterial translocation that further worsens liver damage. Furthermore, this pathogenic mechanism is implicated in most of liver cirrhosis complications, such as spontaneous bacterial peritonitis, hepatorenal syndrome, portal vein thrombosis, hepatic encephalopathy, and hepatocellular carcinoma. After liver transplantation, the decrease in portal pressure should determine beneficial effects on the gut-liver axis, although are incompletely understood data on the modifications of the intestinal permeability and gut microbiota composition are still lacking. How the modulation of the intestinal permeability could prevent the initiation and progression of liver disease is still an uncovered area, which deserves further attention.
肠道和肝脏之间的密切联系和严格的相互合作实现了一个功能实体，称为肠肝轴。肠道屏障的完整性对于维持肝脏内环境稳定至关重要。在这种相互关系中，肝脏作为从肠道易位的潜在有害物质的第二道防火墙，反过来又参与了屏障的调节。越来越多的证据强调了肠道通透性增加和随之而来的细菌易位在肝损伤发展中的相关性。特别是在非酒精性脂肪性肝病患者中，最近的假说认为肠道通透性损害、饮食和肠道菌群失调是主要的致病触发因素。在晚期肝病中，门静脉高压会增强肠道通透性。其临床后果是细菌易位增加，进一步加重肝损伤。此外，这种致病机制与大多数肝硬化并发症有关，如自发性细菌性腹膜炎、肝肾综合征、门静脉血栓形成、肝性脑病和肝细胞癌。肝移植后，门静脉压力的降低应该对肠肝轴产生有益的影响，但关于肠道通透性和肠道微生物群组成的改变的数据仍不完全了解。肠道通透性的调节如何预防肝病的发生和进展仍然是一个未被揭示的领域，值得进一步关注。
