Administration of PSA prevents or reduces the severity of disease in model of TNBS-induced colitis, and Tlr2−/− animals treated orally with PSA are not protected from colitis [37, 77]. B. fragilis can also release PSA in outer membrane vesicles (OMVs) sensed by DC via Tlr2, inducing growth arrest and the production of DNA-damage-inducible protein (Gadd45a) in DC, and an increase in IL-10 production from Foxp3+ iTreg cells [78]. This evidence concerns the gene GADD45A and colitis.