PSA is delivered to the host by outer membrane vesicles (OMVs), secretion structures that target bacterial molecules to host cells. Purified OMVs direct the in vitro differentiation of functional Tregs with potent suppressive activity in a PSA dependent manner. Treatment of animals with OMVs containing PSA prevents experimental colitis and suppresses pro-inflammatory cytokine responses in the gut, and indicate that compositions, medicaments, and methods useful for the treatment of inflammation, and more particularly, inflammatory bowel diseases.
