Virulent Enterococcus faecalis from individuals with Primary Sclerosing Cholangitis crosses the intestinal barrier and induces liver inflammation in Mdr2 -/- mice

Primary Sclerosing Cholangitis (PSC) is characterized by bile duct inflammation and scarring, with alterations in microbiota thought to be involved in disease progression. Notably, biliary Enterococcus species are associated with transplantation-free survival, but mechanistic insights remain unclear. We aimed to investigate E. faecalis strain diversity and its potential role in PSC.

Bile and stool from individuals with PSC and controls were collected. 146 E. faecalis isolates were retrieved and sequenced. Virulence factors were annotated using DIAMOND in BLASTP mode and the VFDB as reference. For functional assays, H69 human cholangiocytes were challenged with E. faecalis lysates, and Interleukin-6 concentration was measured by ELISA. Selected strains were administered to antibiotic pre-treated Mdr2 -/- mice with sclerosing cholangitis. We assessed bacterial translocation to the mesenteric lymph nodes and liver, liver inflammation was assessed by RT-qPCR and flow cytometric analysis.

Genomic analysis highlighted diverse patterns of virulence in bile and stool E.faecalis. The presence of the genes esp and gelE correlated with IL-6 production in vitro. Virulent E. faecalis colonized the mesenteric lymph nodes of Mdr2 -/- mice more frequently than non-virulent E. faecalis, and induced increased expression of proinflammatory chemokines and increased frequencies of TNF producing CD4+T cells in the liver.

E. faecalis virulence genes from patient derived bacteria associated with its inflammatory and translocation potential in Mdr2 -/- mice. These results support the notion that E. faecalis could be relevant in PSC pathogenesis. Further work is needed to assess whether these findings translate into the context of human bile ducts.

Publication History

Article published online:
20 January 2025