Background: Hepatic encephalopathy (HE) is a complex neuropsychiatric syndrome arising from chronic liver disease (CLD). HE manifests with symptoms such as poor memory, impairment in motor coordination, lethargy and coma. The gut microbiota has been shown to influence neurological functions via various mediators such as cytokines or bacterial metabolites, many studies have demonstrated the gut-brain axis is altered in liver disease. Faecal matter transplantation (FMT) in patients with cirrhosis has revealed beneficial effects yet many limitations of these studies render the results inconclusive. Purpose: The aim of this study is to explore the impact of FMT on gut microbiota and the beneficial effects on neuro behaviour in bile-duct ligated (BDL) rats. Method: Male Sprague-Dawley rats were randomly assigned to one of three groups; SHAM, BDL-VEH (vehicle) and BDL-FMT (who received FMT daily from pooled faeces from SHAM rats). After five weeks, behaviour tests were performed to evaluate short- and long-term memory (Novel Object Recognition), anxiety (Open Field and Elevated Plus Maze) and motor coordination (Rotarod). Plasmatic parameters such as cytokines, short chain fatty acids (SCFA) and liver impairment markers were measured by ELISA, LC-MS/MS and using Cobas respectively. Finally, faeces were collected for bacterial sequencing and SCFA analysis. Results: FMT did not alter degree of liver disease in BDL rats. BDL-VEH developed a loss of short/long term memory and motor coordination compared to SHAM rats. However, alterations in neurological dysfunction were prevented in the BDL-FMT group. FMT did not impact microbiota α-diversity in BDL rats and β-diversity of microbiota was significantly different between all groups. The genera Provotellaceae UCO-001 significantly increased only in SHAM and BDL-FMT rats and Clostridium Senso Stricto 1 significantly increased only in BDL-VEH compared to SHAMs. Finally, Rombustia was only present in SHAM. Plasma pro-inflammatory cytokines (TNF-α & IL-1β) increase in both BDL groups compared to the control group and no difference for the anti-inflammatory cytokine IL-10 was noted. Analysis of short-chain fatty acids in faeces and plasma showed a variation in propionate and butyrate between both BDL groups. Plasma propionate significantly positively correlated with behavioural results. Conclusion: Our results demonstrate that FMT leads to improvement in memory and motor coordination in BDL rats. The microbiota profile was different between BDL-VEH and SHAM, and FMT lead to further alterations on microbiota. The fact that FMT did not normalize microbiota profile compared to SHAM, suggests BDL-FMT leads to a novel specific microbiota profile which in turn protects the brain. The protective effect of plasma propionate needs to be further explored to define its impact on the brain and possible therapeutic application.
