Fecal microbiota transplantation in hepatic encephalopathy: a systematic review

Hepatic encephalopathy (HE) is a reversible neurocognitive dysfunction that ranges in severity from subclinical alterations to coma. Patients with chronic liver disease are predisposed to HE due to metabolic failure and portosystemic shunting of toxins, of which ammonia is believed to be the main toxic chemical. Fecal microbiota transplantation (FMT) may reduce ammonia synthesis by altering the gut microbiota composition to a taxon low in urease, diminish uptake of ammonia by reestablishing the integrity of the intestinal barrier and increase ammonia clearance by improving liver function. In this systematic review, we summarize the insights of the current literature examining FMT as a treatment for HE.PubMed and EMBASE were searched on 08 February 2021 using the MeSH terms 'fecal microbiota transplantation & hepatic encephalopathy' and the abbreviations 'FMT & HE'.Eight studies fulfilled our inclusion criteria, comprising two randomized clinical trials, three case reports and three rodent studies. Thirty-nine patients with HE were treated with FMT. Thirty-nine rodents received FMT in laboratory tests. FMT improved neurocognitive test results in four human studies and two rodent studies. Microbiota originating from donors was found in human recipients one year post-FMT. Readmission of patients was lower after treatment with FMT compared to standard of care.FMT may improve neurocognitive function and reduce serious adverse events in patients with HE, but the studies conducted so far have been small and their long-term follow-up is limited. Large-scale, randomized and controlled trials are needed to validate and help standardize the clinical application of FMT in cases of HE.