Adherent-invasive Escherichia coli pduB drives vitamin B₁₂-dependent colitis in mice

Adherent-invasive Escherichia coli (AIEC) are strongly implicated in the pathogenesis of Crohn's disease, but the virulence factors driving their invasive and pro-inflammatory behavior remain incompletely defined. Here, we demonstrate that vitamin B₁₂ availability modulates pdu-dependent AIEC virulence. The 1,2-propanediol utilization (pdu) operon, which requires vitamin B₁₂ as a cofactor, has previously been associated with bacterial virulence. Here, we validated this association and demonstrated its functional relevance in mouse models of colitis. Deletion of pduB, a structural component of the pdu microcompartment, in the prototypical AIEC strain NRG857c impaired invasion of intestinal epithelial cells without affecting bacterial growth, biofilm formation, or intestinal colonization. In contrast, pduB deletion reduced mucosal association and significantly attenuated colitis in Il10^-/- mice. Moreover, loss of pduB protected against AIEC-induced epithelial barrier dysfunction and reduced expression of pro-inflammatory cytokines, including Il6, Il1b, and Tnf-a. Unexpectedly, pduB deletion was associated with elevated host serum vitamin B₁₂ levels, and exogenous vitamin B₁₂ supplementation directly inhibited AIEC invasion in vitro and effectively protected Il10^-/- mice from AIEC-induced colitis. Furthermore, vitamin B₁₂-mediated suppression of AIEC invasion and barrier dysfunction was dependent on an intact pdu pathway. Together, these findings establish pduB as a key regulator of AIEC virulence. Our findings identify vitamin B₁₂ availability as a host-modifiable factor that influences AIEC pathogenicity, suggesting potential therapeutic strategies for AIEC-driven intestinal inflammation in Crohn's disease.

In this study, we demonstrated that vitamin B₁₂ availability modulates a metabolic interaction between adherent-invasive Escherichia coli (AIEC) and the host micronutrient vitamin B₁₂ that influences AIEC epithelial invasion. We confirm that a gene within the 1,2-propanediol utilization pathway (pduB) is critical for AIEC invasion and the development of intestinal inflammation in multiple mouse models. We further identify that vitamin B₁₂, a cofactor for metabolic reactions within the Pdu microcompartment, is altered in the host during infection, suggesting changes in the microbe-host vitamin B₁₂ utilization dynamics. Functionally, we also show that vitamin B₁₂ supplementation significantly inhibited AIEC invasion of epithelial cells in vitro. Lastly, we found that vitamin B₁₂ supplementation provided strong protection against AIEC-induced colitis in Il10^-/- mice, preventing weight loss, rectal prolapse, tissue damage, and inflammatory infiltration, even in animals colonized with wild-type AIEC. Broadly, our work highlights vitamin B₁₂ availability as a modifiable host factor that influences AIEC pathogenicity and suggests new therapeutic avenues for therapeutic strategies targeting microbe-nutrient interactions in inflammatory bowel disease.