We observed microbial invasion of the mucus layer in healthy villin-TNFAIP3 mice which do not develop colitis but do exhibit increased FoxP3+ve Tregs in their mucosa.26 These Foxp3+ve Tregs might be preventing colitis from occurring in villin-TNFAIP3 mice, and the lack of these cells in TRAG mice might therefore contribute to the spontaneous development of innate immune mediated IBD we observe in TRAG mice. Here, FOXP3 is linked to colitis.