Gut microbiota-related complications in cirrhosis

Abstract

Gut microbiota plays an important role in cirrhosis. The liver is constantly challenged with commensal bacteria and their products arriving through the portal vein in the so-called gut-liver axis. Bacterial translocation from the intestinal lumen through the intestinal wall and to mesenteric lymph nodes is facilitated by intestinal bacterial overgrowth, impairment in the permeability of the intestinal mucosal barrier, and deficiencies in local host immune defences. Deranged clearance of endogenous bacteria from portal and systemic circulation turns the gut into the major source of bacterial-related complications. Liver function may therefore be affected by alterations in the composition of the intestinal microbiota and a role for commensal flora has been evidenced in the pathogenesis of several complications arising in end-stage liver disease such as hepatic encephalopathy, splanchnic arterial vasodilatation and spontaneous bacterial peritonitis. The use of antibiotics is the main therapeutic pipeline in the management of these bacteria-related complications. However, other strategies aimed at preserving intestinal homeostasis through the use of pre-, pro- or symbiotic formulations are being studied in the last years. In this review, the role of intestinal microbiota in the development of the most frequent complications arising in cirrhosis and the different clinical and experimental studies conducted to prevent or improve these complications by modifying the gut microbiota composition are summarized.

Keywords: Cirrhosis; Encephalopathy; Portal hypertension; Spontaneous bacterial peritonitis; Microbiota; Bacterial translocation

Core tip: The close relationship between the most frequent complications arising in patients with cirrhosis and the gut microbiota has been intensively studied in the last years and has enhanced the relevance of the constant communication between the gut and the liver in the management of patients with cirrhosis. This review intends to integrate the existing knowledge of the role of intestinal microbiota plays in the development of these complications and the evidence on the possible efficacy of gut-microbiota modulating strategies to help in their management.