The multi-omic basis for hepatic encephalopathy recurrence: Analysis of the THEMATIC trial

The THEMATIC trial demonstrated that fecal microbiota transplantation (FMT) reduces recurrence of hepatic encephalopathy (HE) in patients already receiving lactulose and rifaximin. The aim of this analysis was to identify multi-omic predictors of HE recurrence among THEMATIC trial participants.

The THEMATIC trial enrolled patients with cirrhosis and HE who received oral or enema FMT vs. placebo (1-3 administrations) and were followed for 6 months. Outcomes included safety and HE recurrence. Serum, urine, and stool samples were collected at baseline and post-FMT for all participants. Stool metagenomics, serum and urine metabolomics, inflammatory cytokines, and clinical data were analyzed. Differences between patients with and without HE recurrence were assessed using pathway, random forest, and latent factor analyses.

HE recurred in 10 of 60 patients (17%), with significantly higher recurrence in the placebo vs. the FMT groups (40% vs. 8%; p = 0.005). Due to the low recurrence rate in the FMT arms, all patients with recurrence were combined and compared with those without recurrence. Stool metagenomics showed that the abundance of short-chain fatty acid (SCFA) producers (Faecalibacterium, Eubacterium, Bacteroides, Blautia spp.) was lower, while that of GABA-producing taxa (Lactobacillus, Bifidobacterium spp.) was higher, in patients with recurrence. Urine and serum metabolomes separated HE recurrence groups on PLS-DA, with serum butyrate and isobutyrate being most significantly associated (p = 0.008). Pathway analyses revealed upregulation of GABA and neurotransmitter pathways in patients with HE recurrence. Random forest and latent factor analysis indicated that SCFA producers and secondary bile acids were protective, whereas IL-6, GABA producers, nicotine metabolites, and primary bile acids were associated with HE recurrence.

Secondary analysis of the THEMATIC randomized controlled trial indicates that HE recurrence in patients on lactulose and rifaximin is associated with distinct microbiome and metabolomic profiles, particularly involving SCFAs, GABA metabolism, bile acids, and IL-6.

Fecal microbiota transplantation (FMT) reduced hepatic encephalopathy (HE) recurrence in patients receiving lactulose and rifaximin in the THEMATIC trial, but the multi-omic mechanisms underlying this effect were unclear. In this secondary analysis, we found that HE recurrence - regardless of FMT or placebo assignment - was associated with distinct multi-omic signatures, including reduced short-chain fatty acid-producing and increased pathobiont taxa, lower urinary and serum short-chain fatty acids, secondary bile acids, and acetaminophen derivatives, and higher GABA-related and nicotine metabolites, along with elevated IL-6 levels. Notably, patients with greater donor microbiota engraftment had lower rates of HE recurrence. These findings suggest that HE recurrence after FMT reflects a multifactorial process involving alterations in gut metagenomics, systemic metabolomics, inflammation, and donor engraftment.

www.clinicaltrials.gov: NCT03796598.