The gut-liver axis refers to the bidirectional relationship between the gut and its microbiota, and the liver, resulting from the integration of signals generated by dietary, genetic and environmental factors. This reciprocal interaction is established by the portal vein which enables transport of gut-derived products directly to the liver, and the liver feedback route of bile and antibody secretion to the intestine. The intestinal mucosal and vascular barrier is the functional and anatomical structure that serves as a playground for the interactions between the gut and the liver, limiting the systemic dissemination of microbes and toxins while allowing nutrients to access the circulation and to reach the liver. The control of microbial communities is critical to maintaining homeostasis of the gut-liver axis, and as part of this bidirectional communication the liver shapes intestinal microbial communities. Alcohol disrupts the gut-liver axis at multiple interconnected levels, including the gut microbiome, mucus barrier, epithelial barrier and at the level of antimicrobial peptide production, which increases microbial exposure and the proinflammatory environment of the liver. Growing evidence indicates the pathogenetic role of microbe-derived metabolites, such as trimethylamine, secondary bile acids, short-chain fatty acids and ethanol, in the pathogenesis of non-alcoholic fatty liver disease. Cirrhosis by itself is associated with profound alterations in gut microbiota and damage at the different levels of defence of the intestinal barrier, including the epithelial, vascular and immune barriers. The relevance of the severe disturbance of the intestinal barrier in cirrhosis has been linked to translocation of live bacteria, bacterial infections and disease progression. The identification of the elements of the gut-liver axis primarily damaged in each chronic liver disease offers possibilities for intervention. Beyond antibiotics, upcoming therapies centred on the gut include new generations of probiotics, bacterial metabolites (postbiotics), faecal microbial transplantation, and carbon nanoparticles. FXR-agonists target both the gut and the liver and are currently being tested in different liver diseases. Finally, synthetic biotic medicines, phages that target specific bacteria or therapies that create physical barriers between the gut and the liver offer new therapeutic approaches.
Acute‐on‐chronic liver failure (ACLF) is characterized by acute decompensation (AD) of cirrhosis, organ failure(s), and high 28‐day mortality. We investigated whether assessments of patients at specific time points predicted their need for liver transplantation (LT) or the potential futility of their care. We assessed clinical courses of 388 patients who had ACLF at enrollment, from February through September 2011, or during early (28‐day) follow‐up of the prospective multicenter European Chronic Liver Failure (CLIF) ACLF in Cirrhosis study. We assessed ACLF grades at different time points to define disease resolution, improvement, worsening, or steady or fluctuating course. ACLF resolved or improved in 49.2%, had a steady or fluctuating course in 30.4%, and worsened in 20.4%. The 28‐day transplant‐free mortality was low‐to‐moderate (6%‐18%) in patients with nonsevere early course (final no ACLF or ACLF‐1) and high‐to‐very high (42%‐92%) in those with severe early course (final ACLF‐2 or ‐3) independently of initial grades. Independent predictors of course severity were CLIF Consortium ACLF score (CLIF‐C ACLFs) and presence of liver failure (total bilirubin ≥12 mg/dL) at ACLF diagnosis. Eighty‐one percent had their final ACLF grade at 1 week, resulting in accurate prediction of short‐ (28‐day) and mid‐term (90‐day) mortality by ACLF grade at 3‐7 days. Among patients that underwent early LT, 75% survived for at least 1 year. Among patients with ≥4 organ failures, or CLIF‐C ACLFs >64 at days 3‐7 days, and did not undergo LT, mortality was 100% by 28 days. Conclusions: Assessment of ACLF patients at 3‐7 days of the syndrome provides a tool to define the emergency of LT and a rational basis for intensive care discontinuation owing to futility. (Hepatology 2015;62:243‐252)
Infections ACLF Death Different clinical courses of acutely decompensated cirrhosis Pre-ACLF Unstable decompensated cirrhosis Stable decompensated cirrhosis 0 90 180 270 360 Days Highlights Patients with acutely decompensated cirrhosis without ACLF develop 3 different clinical courses. Patients with pre-ACLF develop ACLF within 90 days and have high systemic inflammation and mortality. Patients with unstable decompensated cirrhosis suffer from complications of severe portal hypertension. Patients with stable decompensated cirrhosis have less frequent complications and lower 1-year mortality risk.
Financial support: The study was supported by the European Foundation for the Study of Chronic Liver Failure (EF-Clif). EF-Clif received unrestricted donations from Grifols and Cellex Foundations and is partner or contributor in several projects of the EU Horizon 2020 research program. Maria Papp was supported by the Janos Bolyai Research Scholarship of the Hungarian Academy of Science (BO/00232/17/5) and the New National Excellence Program of the Ministry of Human Capacities (ÚNKP-18-4 Bolyai Plus). Pere Ginès is a recipient of the ICREA ACADEMIA AWARD (2015-2020). Disclosures The EASL-CLIF Consortium is a network of 101 European University hospitals supported by the EF-Clif. EF-Clif is a private non-profit organization aimed at improving clinical and translational research in cirrhosis. The scientific agenda of the EASL-CLIF Consortium and the specific research protocols are made exclusively by the Steering Committee members without any participation of pharmaceutical companies.
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