NOD2 regulation of Toll-like receptor responses and the pathogenesis of Crohn’s disease

[...]while there is ample evidence that experimental colitis can be due to deficient regulatory cell responses, there are few data that this is the case in human Crohn's disease. 26 Secondly, while van Heel and colleagues 23 have shown that NOD2 signalling enhances TLR9 signalling, 23 there is no evidence that TLR9 signalling by itself can induce regulatory T cells.