AIEC-dependent pathogenic Th17 cell transdifferentiation in Crohn's disease is suppressed by rfaP and ybaT deletion

Abstract

Mucosal enrichment of the Adherent-Invasive E. coli (AIEC) pathotype and the expansion of pathogenic IFNγ-producing Th17 (pTh17) cells have been linked to Crohn's Disease (CD) pathogenesis. However, the molecular pathways underlying the AIEC-dependent pTh17 cell transdifferentiation in CD patients remain elusive. To this aim, we created and functionally screened a transposon AIEC mutant library of 10.058 mutants to identify the virulence determinants directly implicated in triggering IL-23 production and pTh17 cell generation. pTh17 cell transdifferentiation was assessed in functional assays by co-culturing AIEC-infected human dendritic cells (DCs) with autologous conventional Th17 (cTh17) cells isolated from blood of Healthy Donors (HD) or CD patients. AIEC triggered IL-23 hypersecretion and transdifferentiation of cTh17 into pTh17 cells selectively through the interaction with CD-derived DCs. Moreover, the chronic release of IL-23 by AIEC-colonized DCs required a continuous IL-23 neutralization to significantly reduce the AIEC-dependent pTh17 cell differentiation. The multi-step screenings of the AIEC mutant's library revealed that deletion of ybaT or rfaP efficiently hinder the IL-23 hypersecretion and hampered the AIEC-dependent skewing of protective cTh17 into pathogenic IFNγ-producing pTh17 cells. Overall, our findings indicate that ybaT (inner membrane transport protein) and rfaP (LPS-core heptose kinase) represent novel and attractive candidate targets to prevent chronic intestinal inflammation in CD.

Keywords: AIEC; Crohn’s disease; IL-23; pathogenic Th17 cells.

Graphical abstract

Figure 1.

AIEC intracellular persistence within dendritic cells promotes dysregulated IL-23 hypersecretion selectively in CD patients.

Figure 2.

AIEC strongly promotes the transdifferentiation of conventional Th17 cells into pathogenic IFNγ-producing pTh17 cells selectively through the interaction with CD-derived DCs.

Figure 3.

Immunological and functional screening of the AIEC-LF82 mutant library on HD-and CD-derived DCs.

Figure 4.

Conservation of selected AIEC-gene targets among different E. coli pathotypes and phenotypic characterization of the LF82 mutant strains.

Figure 5.

Deletion of the AIEC-determinantsybaT or rfaP drastically impaired the transdifferentiation of cTh17 cells into pTh17 cells.