Outer Membrane Vesicles Secreted by Bacteroides fragilis Inhibit CFTR Chloride Secretion by Human Colon Organoids

Stanton, B.; Barnaby, R.; Nymon, A.; Salerno, P.; Roche, C.; Goo, Y. A.; Cho, B.-K.; Gardner, T. B.; Svindrych, Z.; Taatjes, D. B.; Hampton, T. H.; Ross, B. D.

doi:10.1101/2025.08.19.671135

bioRxiv · 10.1101/2025.08.19.671135

Outer Membrane Vesicles Secreted by Bacteroides fragilis Inhibit CFTR Chloride Secretion by Human Colon Organoids

Stanton, B.·Barnaby, R.·Nymon, A.·Salerno, P.·Roche, C.·Goo, Y. A.·Cho, B.-K.·Gardner, T. B.·Svindrych, Z.·Taatjes, D. B.·Hampton, T. H.·Ross, B. D.

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Abstract

The goals of this study were to develop a model to study host pathogen interactions in primary human colon organoids and to test the hypothesis that Bacteroides fragilis toxin (BFT-2) secreted in outer membrane vesicles (OMVs) modulates mucosal immunity and CFTR Cl- secretion. Since Bacteroides species reside in mucus, OMVs are likely to represent a mechanism of communication between Bacteroides and the host. Two strains of Bacteroides were studied, Enterotoxigenic Bacteroides fragilis (ETBF), which produces BFT-2, and the non-toxigenic Bacteroides fragilis strain NCTC 9343 (NTBF) that does not produce BFT-2. We also utilized two additional strains of Bacteroides fragilis: one in which bft-2 was knocked out (ETBF {Delta}bft), and one that was engineered to contain bft-2 (NTBF+bft). We report that Bacteroides fragilis OMVs reduced CFTR Cl- secretion but had no effect on tight junction or cell adhesion proteins, transepithelial resistance (TER) or cytokine secretion by primary human colon organoids. NTBF OMVs containing BFT-2 were more effective in reducing CFTR Cl- secretion than NTBF lacking BFT-2. We conclude that OMVs secreted by Bacteroides can be an important mechanism of host pathogen interactions in the colon by reducing CFTR Cl- secretion.

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Stanton, B., Barnaby, R., Nymon, A., Salerno, P., Roche, C., Goo, Y. A., Cho, B.-K., Gardner, T. B., Svindrych, Z., Taatjes, D. B., Hampton, T. H., Ross, B. D.. 2025-08-19. Outer Membrane Vesicles Secreted by Bacteroides fragilis Inhibit CFTR Chloride Secretion by Human Colon Organoids. https://doi.org/10.1101/2025.08.19.671135

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